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1
Baskakova, Alevtina. « Synthesis of branched [alpha]-[alpha-] and [beta]-amino[beta-amino] acids using C-nucleophile additions to imines and nitrones ». Berlin Logos-Verl, 2009. http://d-nb.info/99789301X/04.
Texte intégral
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Rai, Neelam. « Greener synthesis and 1, 3-dipolar cycloaddition reactions of a amino nitrones and studies of biological activities of the cycloadducts ». Thesis, University of North Bengal, 2017. http://ir.nbu.ac.in/handle/123456789/2663.
Texte intégral
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Theddu, Naresh. « APPLICATIONS OF ENANTIOPURE SULFINIMINE DERIVED CHIRAL AMINE BUILDING BLOCKS FOR THE ASYMMETRIC SYNTHESIS OF TROPANE ALKALOIDS AND CYCLIC CIS BETA-AMINO ACID DERIVATIVES ». Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/157444.
Texte intégralRésumé :
ChemistryPh.D.
Chiral amines are ubiquitous in natural products and are found in many drugs and drug candidates. Enantiopure sulfinimines [RS(O)N=CHR1] are useful chiral building blocks for the stereoselective synthesis of amines and amine derivatives. The aim of this thesis research is to develop new methods to access chiral amine building blocks for applications in the synthesis of nitrogen-heterocycles including ring-substituted tropinones, tropanes, cyclic cis-beta-amino acid derivatives, and amino-cyclopentitols.
Temple University--Theses
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Bose, Rajib Kumar. « 1, 3 -Dipolar cycloaddition of * -Amino nitrone ». Thesis, University of North Bengal, 1993. http://hdl.handle.net/123456789/760.
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Mugode, Luke. « Free amino nitrogen improvement in sorghum malt brewing ». Diss., University of Pretoria, 2009. http://hdl.handle.net/2263/27301.
Texte intégralRésumé :
Although sorghum malt is relatively rich in free amino nitrogen (FAN), the 150 mg FAN/L threshold recommended for brewing is difficult to obtain. The vitreous nature of the sorghum endosperm hinders proteolysis during brewing. Hence, exogenous proteolytic enzymes are often required to increase hydrolysis of sorghum malt protein to produce sufficient FAN in order to support rapid yeast growth during fermentation. Ten exogenous proteases were examined for their production of FAN in sorghum malt mashing. Mashing was done at 550C for 45 minutes. Levels of FAN, as determined by the ninhydrin method, showed great variation among the proteolytic enzymes, ranging from 96 in control to 182 mg/100 g malt with possibly of most effective proteolytic enzyme. The variation in FAN level was possibly due to different optimal mashing conditions of exogenous proteases used and perhaps due to low ratios of exopeptidase/endopeptidase in the enzyme preparations. Low temperature (400C) and long duration mashing for (7 hours) gave good FAN production during mashing to a total of 113 and 138 mg/100 g malt in control and the treatment with exogenous proteolytic enzyme Flavourzyme plus malt, respectively. The exogenous enzyme (Flavourzyme) plus potassium metabisulphite (PMB) increased FAN production during mashing in the ratio of 2 to 1 in a treatment where PMB was added compared to one without. Similarly, hot wort extract (HWE) increased by 8% during mashing with exogenous enzyme plus PMB compared to one without PMB, respectively. PMB was involved in destabilizing the disulphide bonds in the sorghum protein polypeptide chains allowing proteolytic enzymes better accessibility to proteins. The increase in HWE was possibly due to the starch being freed from the sorghum protein matrix. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed some oligomeric and polymeric kafirins after mashing. With transmission electron microcopy (TEM), protein bodies of varying sizes with partially degraded peripheral edges and some holes were seen after mashing. SDS-PAGE and TEM results suggest insufficient proteolysis. High protein digestibility sorghum’s potential for brewing was examined with reference to FAN production. Although during mashing FAN increased by approx. 82 and 115% for unmalted normal and high digestibility sorghums, respectively, the 150 mg FAN/L threshold, recommended for brewing was not achieved. FAN production to levels above 150 mg/L may only be realized if normal sorghum malt or high protein digestibility sorghum malt is mashed with exogenous enzymes containing sufficient exopeptidases coupled with appropriate mashing conditions. CopyrightDissertation (MSc)--University of Pretoria, 2009.
Food Science
unrestricted
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Ng'andwe, Chisala Charles. « Free amino nitrogen improvement in sorghum grain brewing ». Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01292009-155720.
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Svennerstam, Henrik. « Amino acid uptake in Arabidopsis : the transporters involved, kinetics of uptake and growth on amino acids / ». Umeå : Dept. of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200850.pdf.
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Henry, Neil. « From β-amino alcohols to highly functionalised nitrogen heterocycles ». Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426127.
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Quayle, Wendy C. « The diagenesis of nitrogen in recent sediments ». Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295502.
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Roseblade, Stephen. « Intramolecular asymmetric nitrone cycloadditions in the synthesis of β amino acids ». Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251146.
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Antilley, Teri Jill. « Evaluating the technique of using nitrogen retention as a response criterion for amino acid studies in the horse ». Texas A&M University, 2003. http://hdl.handle.net/1969.1/5780.
Texte intégralRésumé :
Six Quarter Horse yearling fillies were used in a duplicated 3 x 3 Latin square
designed experiment to evaluate the technique of nitrogen retention as a response
criterion for amino acid studies in the horse. The yearlings were paired by age and
randomly assigned to one of three concentrates fed with a medium quality Coastal
Bermudagrass hay throughout the study. Diets were fed at approximately 1.9% of horse
body weight per day, divided into twice daily feedings with a 60:40 concentrate: hay
ratio. With the exception of lysine and threonine, proposed amino acid requirements for
yearling horses were calculated using nutrient to calorie ratios of gilts weighing 80-120
kg and gaining 325 g/d.
Diet A was amino acid sufficient, as provided by a soybean meal-based concentrate.
Diet B was amino acid deficient, with a cottonseed hull-based concentrate. Diet A and
Diet B were isonitrogenous, containing approximately 12% crude protein. Diet C used
the identical concentrate as Diet B, with synthetic essential amino acids and cysteine
orally dosed to match the amino acid levels in Diet A. Nitrogen retention was not
different between Diet A and Diet B. Diet C resulted in differences from Diets A and B
in nitrogen retention; however, differences were a consequence of nitrogen intake. Nitrogen retained as a percent of nitrogen absorbed was lower (P < 0.05) for Diet B than
for Diet A, for data not accounting for endogenous fecal and urinary losses. There were
no differences in nitrogen retained as a percent of nitrogen absorbed for horses fed Diet
C, when compared to either Diet A or Diet B, for data not accounting for endogenous
losses.
It was concluded that differences in nitrogen retained as a percent of nitrogen
absorbed were observed between amino acid sufficient diets and amino acid deficient
diets. However, horses fed amino acid deficient diets and orally dosed with synthetic
amino acids, likely require some modified dosage level to achieve the same or higher
values in nitrogen retained as a percent of nitrogen absorbed as those values for amino
acid sufficient diets.
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Rees, David Owen. « Enantioselective synthesis of isotopically labelled amino acids and nitrogen heterocycles ». Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440010.
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Rozgowska, Emma Jayne. « N-amino heterocycles : applications in flash vacuum pyrolysis ». Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5280.
Texte intégralRésumé :
Routes to N-amino heterocycles were reviewed and findings applied to generate flash vacuum pyrolysis (FVP) precursors of two types - ketene generators and azol-1-yl radical generators. N-Amino heterocycles can be used as nitrogen radical generators, the N-N bond being homolytically cleaved at furnace temperatures of approximately 850 °C. A number of 2-substituted benzimidazoles were synthesised and subsequently Naminated. The 2-arylbenzimidazole precursors 1-amino-2-(2-methylphenyl)-1Hbenzimidazole and 1-amino-2-(2-ethylphenyl)-1H-benzimidazole were synthesised and subjected to FVP. The hydrogen transfer processes of the resulting azol-1-yl radicals were investigated. Pyrolysis of 1-amino-2-(2-methylphenyl)-1Hbenzimidazole resulted in three products; 2-(2-methylphenyl)-1H-benzimdazole, 11H-benzo[4,5]imidazo[1,2-a]isoindole and 1-(2-methylphenyl)-1Hbenzo[ d]imidazol-2-amine. Pyrolysis of 1-amino-2-(2-ethylphenyl)-1Hbenzimidazole resulted in five products, four of which have been successfully isolated and identified as 2-(2-ethylphenyl)-1H-benzimidazole, 5,6- dihydrobenzo[4,5]imidazo[2,1-a]isoquinoline, 1-(2-ethylphenyl)-1Hbenzo[ d]imidazol-2-amine and 11-methyl-11H-benzo[4,5]imidazo[2,1-a]isoindole. The mechanism of formation of most products is initiated by hydrogen atom transfer to the azol-1-yl radical position. N-Aminopyrazole was reacted with 5-methoxymethylene-2,2-dimethyl-1,3-dioxane- 4,6-dione to form the corresponding 5-(N-aminopyrazolyl)methylene derivative, which, when subjected to FVP, eliminates acetone and carbon dioxide to form a methyleneketene. This subsequently undergoes a [1,3]-hydrogen shift giving an imidoylketene which can collapse onto the neighbouring nitrogen atom forming pyrazolo[1,2-a][1,2,3]triazin-5-ium-4-olate (a novel heterocyclic mesomeric betaine system) or cyclise onto the adjacent carbon atom to yield a pyrazolopyridazinone. On variation of the furnace temperature it was apparent the former forms at relatively moderate temperatures (~500 °C) whereas the latter begins to predominate as the furnace temperature increases (~700 °C). The relationship between these kinetic and thermodynamic products was modelled using DFT calculations. By using substituted pyrazole precursors, substituents could be incorporated into all three available positions around the pyrazole ring. Using substituted acrylic esters as alternative imidoylketene generators, substituents could also be incorporated into both available positions in the pyridazinone ring. All corresponding betaine and pyrazolopyridazinone products were isolated and characterised.
14
Ma, Li. « Soil Organic Nitrogen - Investigation of Soil Amino Acids and Proteinaceous Compounds ». Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51960.
Texte intégralRésumé :
Soil carbon (C) and nitrogen (N) are predominantly in organic form. Proteins/ peptides, as an important organic form of N, constitute a substantial part of soil organic matter. On one hand, proteins/peptides are an important N source for plants and microorganisms, particularly in soils where inorganic N is limited. On the other hand, their stabilization in soils by forming organo-mineral associates or macromolecule complex reduces the C loss as CO2 into the atmosphere. Therefore, studies on the turnover, abundance, composition, and stability of proteins/peptides are of crucial importance to agricultural productivity and environmental sustainability. In the first part of this study, the bioavailability and distribution of amino acids, (building block of proteins/peptides), were investigated, in soils across the North-South and West-East transects of continental United States. The second part of this study aimed to understand the variations of organic C speciation in soils of continental United States. Previous investigations of the interactions between soil minerals and proteins/peptides were mostly limited to batch sorption experiments in labs, seldom of which gave the details at the molecular scales. Therefore, in the third part of this study, the molecular orientation of self-assembled oligopeptides on mineral surfaces was investigated by employing synchrotron based polarization-dependent Near Edge X-ray Adsorption Fine Structure Spectroscopy (NEXAFS) techniques. Specific aims of this study were: 1) to assess potentially bioavailable pool of proteinaceous compounds and the immediately bioavailable pool of free amino acids in surface and subsurface soils of various ecosystems; 2) to evaluate the relationship between environmental factors and levels/composition of the two pools; 3) to investigate the organic C speciation in soils of various land use; and 4) to understand molecular level surface organization of small peptides on mineral surfaces.
The levels of free amino acids and hydrolysable amino acids which represent the potentially bioavailable pool of proteinaceous compounds in A-horizon soils were significantly high than in C-horizon soils due to the accumulation of organic matter in surface. On average, free amino acids accounted for less than 4 % of hydrolysable amino acids which represent the total proteinaceous compounds in soils. The composition of free amino acids was significantly different between surface soil and subsurface soil and was significantly influenced by mean annual temperature and precipitation. A relatively uniform composition of hydrolysable amino acids was observed irrespective of a wide range of land use. Significant variations were observed for the levels of free and hydrolysable amino acids along mean annual temperature and precipitation gradients, as well as among vegetation types of continental USA, suggesting levels of free and hydrolysable amino acids were associated with the above-ground biomass and root distribution. Organic C speciation investigation revealed the presence of carboxylic-C (38%), aliphatic-C (~ 22%), aromatic-C (~ 18%), O/N-alkyl-C (~ 16%), and phenolic-C (< 6%). Factors such as temperature and vegetation cover were revealed in this study to account for the fluctuations of the proportions of aromatic-C and phenolic-C, in particular. Phenolic-C may serve as a good indicator for the effect of temperature or vegetation on the composition of SOC. The average composition of soil organic C, over the continental scale, was relatively uniform over various soil ecosystems and between two soil horizons irrespective of surface organic C content. Polarization dependent NEXAFS analysis showed the oligopeptides tend to orient on mineral surface with an average tilt angle of 40 ° between the molecular chain and the mineral surface.Ph. D.
15
Atasoglu, Cengiz. « Regulation of amino acid and ammonia utilisation by ruminal microorganisms ». Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327300.
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Flannery, Matthew Brett. « The fate of nitrogen-containing biomolecules in modern and ancient integuments ». Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322614.
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Hao, Jing. « Synthesis of novel enantiopure trifluoromethyl nitrogen-containing scaffolds ». Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS261.
Texte intégralRésumé :
Les composés fluorés ont montré une importance croissante dans le développement d'agents pharmaceutiques en raison des propriétés exceptionnelles de l'atome de fluor. Dans cette thèse, nous nous sommes concentrés sur la synthèse des composés énantiopurs contenant de l'azote.A partir de l'aldimine trifluorométhylée, une réaction d’aza-Baylis-Hillman asymétrique a été réalisée et a permis d’obtenir un nouvel acide (R)-α-méthylène-β-CF3-β-aminé avec un bon rendement et une excellente diastéréosélectivité. Puis, en utilisant une réaction d’allylation dans les conditions de Barbier, de nouveaux acides aminés trifluorométhylés cycliques à cinq ou six chaînons ont été obtenus avec de bons rendements et d’excellents diastéréosélectivités. En particulier des acides γ et β-aminés, comme la CF3-β-proline, qui est très intéressante dans la synthèse peptidique.Enfin, grâce à l'addition d'éther de vinyle sur l’aldimine trifluorométhylée, différentes amines trifluorométhylées ont été obtenues. Parmi ces composés, les amino-alcools CF3 qui sont très utiles pour la conception de médicaments et dans la synthèse asymétrique, et les amines cycliques trifluorométhylées qui peuvent servir de bon substrat pour synthétiser des composés CF3-cycliques plus fonctionnalisésFluorinated compounds have shown a growing importance in the development of pharmaceutical agents owing to the outstanding properties of the fluorine atom. In this thesis, we focused on the synthesis of enantiopure trifluoromethyl nitrogen-containing compounds.Starting from the trifluoromethyl aldimine, firstly, an asymmetric aza-Baylis–Hillman reaction was realized with high reaction rates, and diastereoselectivities, and the previously unknown enantiomerically pure (R)-α-methylene β-CF3 β-amino acid was obtained in good yield. Then, through aza-Barbier reaction, the five-membered and six-membered trifluoromethyl cyclic amino acids were obtained, including β-amino acid and γ-amino acid, especially CF3-β-proline, which is very interesting in the further peptide synthesis.Finally, through the addition of vinyl ether to imine, different novel trifluoromethylated amines were afforded. Among these compounds, CF3-amino alcohols are very useful in drug design and asymmetric synthesis, and enantiopure CF3-cyclic amine is a very good substrate to synthesize more functionalized CF3-cyclic compounds
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Silva, Joana Diniz Rosa da. « Frações nitrogenadas em caldos de diferentes cultivares de cana-de-açúcar / ». Jaboticabal : [s.n.], 2011. http://hdl.handle.net/11449/96827.
Texte intégralRésumé :
Orientador: Marcos Omir MarquesBanca: José Fernando Durigan
Banca: Ricardo da Silva Sercheli
Resumo: A caracterização e quantificação das frações nitrogenadas presentes no caldo de diferentes cultivares de cana-de-açúcar pode facilitar a identificação da principal aptidão industrial da mesma para a produção de açúcar (baixos teores de nitrogênio), ou de etanol e cachaça (altos teores de nitrogênio). A hipótese deste trabalho é que diferentes cultivares precoces, médios e tardios possam produzir caldos com diferentes teores de nitrogênio e, portanto serem utilizados com maior desempenho nos processos de fermentação ou na produção de açúcar. Este trabalho tem como objetivo quantificar as frações nitrogenadas (amoniacal, protéica, total, não-protéica e amínica) em caldos de dezoito cultivares de cana-de-açúcar em soqueiras de segundo corte. O delineamento experimental utilizado foi o inteiramente casualizado com parcelas subdividas e três repetições. Foram avaliados dezoito cultivares com três ciclos de maturação, em 5 épocas (0, 28, 69, 112 e 154 dias) durante o ano agrícola 2010/2011. No destilado, obtido a partir do caldo procedeu-se a determinação do nitrogênio amoniacal de acordo com o método de micro-Kjeldahl. Os teores de nitrogênio total e nitrogênio não-protéico, determinado em caldo desproteinizado com hidróxido de bário a 0,3N e sulfato de zinco a 5%, também foram determinados pelo método de micro-Kjeldahl. Os teores de nitrogênio protéico e amínico foram estimados por meio de cálculos. Os resultados obtidos foram submetidos à análise de variância (teste F) que quando significativa, as médias foram comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. O cultivar SP91-1049 obteve os maiores valores para as frações de nitrogênio amoniacal, total e protéico, além de maiores teores na interação para as frações amoniacal, protéica e total ao longo das... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The characterization and quantification of nitrogen fractions present in the juice of different varieties of sugar cane can help identify the main industry of the same ability to produce sugar (low levels of nitrogen), or ethanol and cachaça (high levels of nitrogen). The hypothesis is that different early cultivars, middle and late to produce stocks with different levels of nitrogen and therefore be used with higher performance in fermentation processes or the production of sugar. This study aims to quantify the nitrogen fractions (ammonium, protein, total non-protein and amine) in broths eighteen cultivars of sugar cane stumps on the second cut. The experimental design was completely randomized design with subdivided plots and three replications. Eighteen cultivars were evaluated with three cycles of maturation in 5 times (0, 28, 69, 112 and 154 days) during the 2010/2011 agricultural year. The distillate obtained from the broth made the determination of ammonia according to the micro-Kjeldahl method. The levels of total nitrogen and non-protein nitrogen determined in broth deproteinized with barium hydroxide and 0.3 N zinc sulfate 5%, were also determined by micro-Kjeldahl method. The levels of protein and amino nitrogen were estimated by calculations. The results were submitted to analysis of variance (F test) when significant, means were compared by Tukey test at 5% probability. The cultivar SP91-1049 achieved the highest values for the fractions of ammonia nitrogen, total protein and, in addition to higher levels in the interaction for the fractions ammonia, and total protein through the ages. The results indicate that the cultivars studied showed significant differences in levels of nitrogen fractions and the collection times are much greater importance in these levels. The cultivar with a mean cycle of maturation... (Complete abstract click electronic access below)
Mestre
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Meyer-Plath, Asmus Andres. « Grafting of amino and nitrogen groups on polymers by means of plasma functionalisation ». [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=972339787.
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Higham, S. M. « Studies in the relationship between pH, carbohydrate and nitrogen metabolism in human dental plaque ». Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382064.
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Christophersen, Helle Martha. « Putative dicarboxylate and amino acid transporters in soybean (Glycine max L.) : a molecular characterisation ». University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0134.
Texte intégralRésumé :
[Truncated abstract] Some plants, such as legumes, are able to use atmospheric nitrogen as a nitrogen source due to the nitrogen-fixing bacteria residing in specialised root structures called nodules. The exchange of carbon and nitrogen between the host plant (legume) and the nitrogen- fixing micro-symbiont is vital for biological nitrogen fixation. In particular, transport of C4-dicarboxylates, mainly malate, from the plant to the micro-symbiont, and the reverse transport of fixed nitrogen in the form of ammonium are essential for symbiotic nitrogen fixation. In the legume nodule, the symbiosome membrane (SM) surrounds the bacteroid and all exchanges of metabolites and nutrients that occur between the plant and the micro-symbiont must cross this membrane. Recently it has been established that cycling of amino acids across the SM is also critical for optimal symbiotic nitrogen fixation. Therefore to fully understand this agriculturally significant phenomenon, the mechanisms facilitating these exchanges need to be investigated. The major aim of this study was to increase the understanding of nutrient exchange within the nodule at the molecular level by isolating and characterising genes encoding transporters responsible for malate and amino acids transport in soybean (Glycine max, L.), with particular interest in genes significantly or highly expressed in nodules. A combination of molecular and biochemical techniques was used to achieve this. ... Southern blot analysis showed that a small gene family of up to five members encodes these proteins in soybean. A full-length cDNA, designated GmAAP5, was isolated that encodes a novel, putative amino acid transporter. Molecular characterisation of this cDNA and that of GmAAP1 (GenBank Accession no: AY029352), a previously identified putative amino acid transporter gene, was done. Expression analyses showed relatively high expression of GmAAP5 in soybean nodules compared to that in leaf and root tissues, while GmAAP1 showed uniformly high expression in root, leaf and nodule tissues. Phylogenetic analysis of the deduced amino acid sequences of known functional AAPs from dicotyledonous plants revealed that GmAAP1 is most closely related to AAP2 from V. faba, while GmAAP5 is more closely related to AAPs from non-leguminous plants than from leguminous plants. Based on the functional characterisation of the AAPs with which GmAAP1 and GmAAP5 cluster, it is likely that both transporters are neutral and acidic amino acid transporters within the AAP subfamily.
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Ahmadi-Moghadam, Ali. « Nitrogen nutrition of ericoid and ectomycorrhizal systems with special reference to utilization of amino-N sources ». Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299627.
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Simmons, Wyatt J. « Synthesis and Characterization of 2-[bis(2-chloroethyl)amino]-1,3,2-oxazaphospholidin-2-oxides and -sulfide Derivatives ». Youngstown State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1628278595901004.
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Bundy, Rafe. « Use of lactose ['1'5N'1'5N]ureide to quantify colonic salvage of urea-nitrogen ». Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241906.
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Wiedermann, Magdalena. « Responses of peatland vegetation to enhanced nitrogen ». Doctoral thesis, Umeå : Department of Ecology and Environmental Science, Umeå University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1655.
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Heal, Benjamin Mark. « The impact of forage type on the uptake and utilisation of amino acids for growth ». Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341788.
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Kim, Ji-Hyuk. « Effect of amino acid balance on energy and nitrogen metabolism in growing broiler chickens ». Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/28358.
Texte intégralRésumé :
Three experiments were performed to test the assumption that imbalanced dietary amino acid mixtures must lead to increased heat production. The first experiment was based on diets formulated to have a wide range of crude protein concentrations but a fixed concentration of lysine, formulated to be the first-limiting amino acid. In the second experiment, lysine concentration was varied over a wide range while CP content was kept constant. To prevent the masking of dietary effects by thermoregulatory demands, the third experiment was performed at 30°C with the diets similar to the diets used in the second experiment. The detailed relationships among amino acid balance, nitrogen metabolism and energy metabolism were investigated in a computer-controlled chamber calorimetry system. In experiment 1, there was a 75% increase in N intake as CP concentration increased. This led to a 150% increase in N excretion, with no significant change in HP. In experiment 2, there was a 3-fold difference in daily weight gain between the lowest and highest lysine diets HP per bird increased significantly with dietary lysine concentration. There was still an effect when HP was adjusted for body weight differences, but it failed to maintain statistical significance. In experiment 3, HP per bird increased significantly with dietary lysine content, whether or not adjusted for body-weight. The trend was greater than in the previous experiment (20°C). To investigate the effect of amino acid balance and protein quality on growth rate and carcass characteristics, growth trial experiment was performed on a larger scale. Four diets varying CP contents were used. The results showed that there was no significant effect of high protein diet on growth rate and carcass characteristics. A free-choice feeding experiment was also performed to investigate the sensitivity of the bird to its diet on the basis of amino acid balance, especially related to lysine concentration.
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Silva, Joana Diniz Rosa da [UNESP]. « Frações nitrogenadas em caldos de diferentes cultivares de cana-de-açúcar ». Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/96827.
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A caracterização e quantificação das frações nitrogenadas presentes no caldo de diferentes cultivares de cana-de-açúcar pode facilitar a identificação da principal aptidão industrial da mesma para a produção de açúcar (baixos teores de nitrogênio), ou de etanol e cachaça (altos teores de nitrogênio). A hipótese deste trabalho é que diferentes cultivares precoces, médios e tardios possam produzir caldos com diferentes teores de nitrogênio e, portanto serem utilizados com maior desempenho nos processos de fermentação ou na produção de açúcar. Este trabalho tem como objetivo quantificar as frações nitrogenadas (amoniacal, protéica, total, não-protéica e amínica) em caldos de dezoito cultivares de cana-de-açúcar em soqueiras de segundo corte. O delineamento experimental utilizado foi o inteiramente casualizado com parcelas subdividas e três repetições. Foram avaliados dezoito cultivares com três ciclos de maturação, em 5 épocas (0, 28, 69, 112 e 154 dias) durante o ano agrícola 2010/2011. No destilado, obtido a partir do caldo procedeu-se a determinação do nitrogênio amoniacal de acordo com o método de micro-Kjeldahl. Os teores de nitrogênio total e nitrogênio não-protéico, determinado em caldo desproteinizado com hidróxido de bário a 0,3N e sulfato de zinco a 5%, também foram determinados pelo método de micro-Kjeldahl. Os teores de nitrogênio protéico e amínico foram estimados por meio de cálculos. Os resultados obtidos foram submetidos à análise de variância (teste F) que quando significativa, as médias foram comparadas pelo teste de Tukey, ao nível de 5% de probabilidade. O cultivar SP91-1049 obteve os maiores valores para as frações de nitrogênio amoniacal, total e protéico, além de maiores teores na interação para as frações amoniacal, protéica e total ao longo das...
The characterization and quantification of nitrogen fractions present in the juice of different varieties of sugar cane can help identify the main industry of the same ability to produce sugar (low levels of nitrogen), or ethanol and cachaça (high levels of nitrogen). The hypothesis is that different early cultivars, middle and late to produce stocks with different levels of nitrogen and therefore be used with higher performance in fermentation processes or the production of sugar. This study aims to quantify the nitrogen fractions (ammonium, protein, total non-protein and amine) in broths eighteen cultivars of sugar cane stumps on the second cut. The experimental design was completely randomized design with subdivided plots and three replications. Eighteen cultivars were evaluated with three cycles of maturation in 5 times (0, 28, 69, 112 and 154 days) during the 2010/2011 agricultural year. The distillate obtained from the broth made the determination of ammonia according to the micro-Kjeldahl method. The levels of total nitrogen and non-protein nitrogen determined in broth deproteinized with barium hydroxide and 0.3 N zinc sulfate 5%, were also determined by micro-Kjeldahl method. The levels of protein and amino nitrogen were estimated by calculations. The results were submitted to analysis of variance (F test) when significant, means were compared by Tukey test at 5% probability. The cultivar SP91-1049 achieved the highest values for the fractions of ammonia nitrogen, total protein and, in addition to higher levels in the interaction for the fractions ammonia, and total protein through the ages. The results indicate that the cultivars studied showed significant differences in levels of nitrogen fractions and the collection times are much greater importance in these levels. The cultivar with a mean cycle of maturation... (Complete abstract click electronic access below)
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Lamarche, Vanessa Mercia Elizabeth. « The activation of dinitrogen by vanadium diamido-amine complexes and related studies ». Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249113.
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Persson, Jörgen. « Organic nitrogen uptake by boreal forest plants / ». Umeå : Dept. of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s265-ab.html.
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Wischer, Daniela. « Methylated amine-utilising bacteria and microbial nitrogen cycling in Movile Cave ». Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/56877/.
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Movile Cave is an unusual, isolated ecosystem which harbours a complex population of microorganisms, fungi and endemic invertebrates. In the absence of light and with no fixed carbon entering the cave, life is sustained by non-phototrophic microorganisms such as sulfur and methane oxidisers. Also present are methylotrophs that use one-carbon compounds such as methanol and methylated amines as their sole source of carbon and energy. Produced during putrefaction, methylated amines are likely to be major degradation products in Movile Cave. Further to being methylotrophic substrates, they are also a nitrogen source for many non-methylotrophic bacteria. The role of methylated amines as carbon and nitrogen sources for Movile Cave bacteria was investigated using a combination of DNA stable isotope probing and cultivation studies. Both, well-characterised and novel methylotrophs were identified: Methylotenera mobilis dominated 13C-monomethylamine SIP enrichments, while members of Catellibacterium, Cupriavidus and Altererythrobacter were also active. Cultivation studies consolidated SIP results in obtaining the first methylotrophic isolates from the genera Catellibacterium and Mesorhizobium. Pathways for monomethylamine (MMA) metabolism were investigated using new PCR primers designed to target gmaS, the gene for gammaglutamylmethylamide synthetase, a key enzyme of the recently characterised indirect MMA oxidation pathway. This pathway is also present in bacteria that use MMA only as a nitrogen source, while the well-characterised, direct MMA oxidation pathway involving methylamine dehydrogenase (mauA) is found only in methylotrophs. gmaS was present in all MMAutilising isolates, while mauA was found only in some methylotrophs, suggesting the indirect pathway is the major mode of MMA oxidation both in methylotrophs and non-methylotrophs from Movile Cave. Preliminary gmaS surveys revealed a high diversity of gmaS-containing bacteria. The roles of N2 fixers and nitrifiers were also investigated. Both bacterial and archaeal ammonia oxidisers were found to be active; however, sulfur oxidisers appeared to be the dominant autotrophs in Movile Cave.
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Rohde, Laurence Nathaniel Jr. « The Synthesis and Characterization of Diastereomeric 2-[bis(2-chloroethyl)amino]-1,3,2-oxazaphospholidin-2-ones ». Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1533830233099792.
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Thompson, Vanessa R. « Covalent Protein Adduction of Nitrogen Mustards and Related Compounds ». FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1152.
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Chemical warfare agents continue to pose a global threat despite the efforts of the international community to prohibit their use in warfare. For this reason, improvement in the detection of these compounds remains of forensic interest. Protein adducts formed by the covalent modification of an electrophilic xenobiotic and a nucleophilic amino acid may provide a biomarker of exposure that is stable and specific to compounds of interest (such as chemical warfare agents), and have the capability to extend the window of detection further than the parent compound or circulating metabolites. This research investigated the formation of protein adducts of the nitrogen mustard chemical warfare agents mechlorethamine (HN-2) and tris(2-chloroethyl)amine (HN-3) to lysine and histidine residues found on the blood proteins hemoglobin and human serum albumin. Identified adducts were assessed for reproducibility and stability both in model peptide and whole protein assays. Specificity of these identified adducts was assessed using in vitro assays to metabolize common therapeutic drugs containing nitrogen mustard moieties. Results of the model peptide assays demonstrated that HN-2 and HN-3 were able to form stable adducts with lysine and histidine residues under physiological conditions. Results for whole protein assays identified three histidine adducts on hemoglobin, and three adducts (two lysine residues and one histidine residue) on human serum albumin that were previously unknown. These protein adducts were determined to be reproducible and stable at physiological conditions over a three-week analysis period. Results from the in vitro metabolic assays revealed that adducts formed by HN-2 and HN-3 are specific to these agents, as metabolized therapeutic drugs (chlorambucil, cyclophosphamide, and melphalan) did not form the same adducts on lysine or histidine residues as the previously identified adducts formed by HN-2 and HN-3. Results obtained from the model peptide and full protein work were enhanced by comparing experimental data to theoretical calculations for adduct formation, providing further confirmatory data. This project was successful in identifying and characterizing biomarkers of exposure to HN-2 and HN-3 that are specific and stable and which have the potential to be used for the forensic determination of exposure to these dangerous agents.
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Hodgson, Paul B. « A tandem ylide formation and rearrangement approach to the synthesis of nitrogen heterocycles ». Thesis, University of Nottingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261172.
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Norlin, Elin. « Nitrogen isotope analysis of ammonium and glycine : method development for aqueous solutions and soil extracts / ». Umeå : Dept. of Forest Ecology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200584.pdf.
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Francisco, Gil J. « Separation of Carbon Dioxide from Nitrogen Using Poly(vinyl alcohol)-Amine Blend Membranes ». Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2851.
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Abstract
In this research, a facilitated transport membrane was developed. The reactive membrane consisted of a carrier entrapped in poly(vinyl alcohol) "PVA" matrix cast on a polysulfone support. PVA was selected to hold the reactive carrier because of its hydrophilicity and compatibility with the carrier. Several reactive amines were examined for their suitability as carrier. Among the amines tested as a carrier for CO2, diethanolamine "DEA" demonstrates a greater improvement in the permeation of CO2 as well as selectivity over N2. DEA is a secondary amine and one of the most commonly used amines for gas treating due to its favourable reaction kinetics with acid gases and because of its stability when regenerated.
Initially, pure gas permeation was employed for materials selection and membrane preparation procedures. The effects of process conditions on the membrane performance, which involve carrier concentrations, feed pressures and operating temperatures were examined. Then the effects of membrane thickness and long-term stability tests were conducted.
Once the appropriate membrane materials and preparation procedures were established, the next phase of the study involved the determination of the actual separation of CO2/N2 mixtures. These experiments were carried out by adjusting the feed gas composition, feed pressures and operating temperature. In general, the results obtained with CO2/N2 mixtures were in agreement with those obtained with pure gas permeation experiments. It was found that facilitation is more significant at lower CO2 partial pressure differential across the membrane. At higher partial pressure differentials, the reactive membrane may no longer serve as a facilitating medium due to the saturation of the reactive part of the membrane. Under such conditions the permeance values and selectivity obtained were simply due to the solubility and diffusivity of the CO2 and N2 in the membrane matrix.
Since it was not possible to analyze concentration profiles inside the thin membrane experimentally, it was decided to analyze the effects of various parameters through the analytical transport equations. The zwitterion mechanism was used to illustrate the kinetics of the CO2-DEA systems. The mass transport equations were solved numerically. All relevant physicochemical properties needed to implement the mass transport equations were taken from the literatures. The calculated results support the experimental trends that were observed for the CO2 permeance as a function of partial pressure differentials and carrier concentrations.
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Bharadwaj, Gaurav. « Synthesis and Pharmacological Evaluation of Nitrogen Oxide Releasing Prodrugs ». Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301748.
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The main goals of this research were to synthesize nitrogen oxide releasing diazeniumdiolates and their prodrugs and to evaluate their pharmacological effects. The different projects and their results are described below. i. Comparison of HNO and NO donating properties of cyclic amine diazeniumdiolates Diazeniumdiolates are an attractive class of donor compounds as they can be tuned to release NO or both NO and HNO depending upon the amine backbone. Isopropylamine (IPA/NO) and cyclohexylamine (CHA/NO) diazeniumdiolates are currently the only examples of primary amine based diazeniumdiolates. A series of structurally related cyclic amine based diazeniumdiolates were synthesized and characterized. An acetoxymethyl derivative was also synthesized to facilitate cellular uptake and to achieve higher HNO levels in cells. ii. Nitrogen oxide releasing diazeiumdiolate based adducts of N-des-methyl-tamoxifen Nitrogen oxide (NO/HNO) donating diazeniumdiolate adducts of N-desmethyltamoxifen (a key metabolite of the breast cancer drug tamoxifen) were synthesized. DEA/NO-AcOM, an NO donor was also synthesized to monitor the effect of NO on breast cancer cell survival. Derivatives of N-desmethyltamoxifen were found to be effective towards estrogen receptor positive (ER+) cells only. DEA/NO-AcOM was found to be cytotoxic towards estrogen-dependent and independent cell lines, in combination with tamoxifen, or by itself. iii. Synthesis and characterization of nitrogen oxide adducts with non-steroidal anti-inflammatory drugs (NSAIDs) Our group has shown HNO releasing diazeniumdiolate derivatized aspirin to be comparably effective in preventing gastric ulceration to NO-releasing diazeniumdiolate based aspirin analogues. Series of such NSAID adducts were further extended by synthesizing such derivatives of indomethacin and niflumic acid. NO/HNO releasing analogues of aspirin and indomethacin were cytotoxic towards two different breast cancer cell lines, irrespective of estrogen dependence.iv. Chlorambucil analogue of PABA/NOChlorambucil, an alkylating agent is used in leukemia treatment. Tumor cells resistant to alkylating agents often have increased glutathione levels and increased activity of glutathione-S-transferase (GST). PABA/NO is an NO donor with a promising anticancer profile. The chlorambucil analogue of PABA/NO was synthesized to utilize GST for releasing NO and to potentially overcome cellular resistance.
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Phongsawat, Chonticha. « Effect of nutrient limitation in chemostat cultures on amino acid excretion in Clostridium thermocellum ». Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-246982.
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Introduction: Clostridium thermocellum is considered a model organism for consolidated bioprocessing, due to its ability to hydrolyze lignocellulosic biomass more efficiently than many other organisms and to produce ethanol.In order to meet the industrial requirements of ethanol yield and titer, metabolic engineering efforts have been made resulting in a strain that successfully displays increased ethanol yield with reduced amount of some byproducts.However, the ethanol yield in this engineered strain still does not meet the industrial requirements and significant amounts of amino acids are still produced. To attempt to decrease the level of amino acid excretion intended to improve the ethanol yield in C. thermocellum, it is essential to understand its metabolism and how it is affected by different cultivation conditions and mediumcompositions. This study aimed to gain an insight in how carbon- and nitrogenlimitation affect amino acid excretion in C. thermocellum, with the hypothesisthat excess of carbon and nitrogen yields more amino acid excretion. Methods: Mass-balance based calculations of rates and yields were used to analyze the metabolism of a wild-type of C. thermocellum (DSM 1313) grownanaerobically in carbon- or nitrogen-limiting chemostats. For this, Low-Carbonmedium containing, respectively, cellobiose (5 g/L) and urea (0.15 g/L) as the limiting nutrient was used. Both cultivations were performed at 55 °C, pH 7.0and 400 RPM shaking at a dilution rate of 0.1 h-1.Conclusions: Considering yields of total amino acids excreted in both limitations, it was hypothesized that C. thermocellum exploited the amino acid excretion to maintain carbon balance around the pyruvate node caused by excess of the carbon. Based on yield of valine excreted in particular, it was hypothesized that amino acid excretion was used to maintain redox balance in the metabolism of C. thermocellum, where malate shunt could play a major role.However, results of the Carbon-limitation did not allow any conclusion of nitrogen excess having an effect on amino acid excretion in C. thermocellum.
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Hussein, Ali Hussein. « Effects of ammonia loading on lysine utilization by growing cattle ». Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20118.
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Master of ScienceAnimal Sciences and Industry
Evan C. Titgemeyer
Six ruminally-cannulated Holstein steers (202 ± 15 kg) were used to study the effects of ruminal ammonia loading on whole-body lysine utilization. Steers were housed in metabolism crates and used in a 6 × 6 Latin square design. All steers received 2.52 kg of DM/d of a diet (10.1% CP) containing 82% soybean hulls, 8% wheat straw, 5% cane molasses, and 5% vitamins and minerals. Ten g/d of urea was infused continuously into the rumen of all steers to ensure adequate ruminal ammonia concentrations; concurrently, steers were ruminally infused continuously with 200 g/d acetic acid, 200 g/d propionic acid, and 50 g/d of butyric acid and abomasally infused with 300 g/d of glucose continuously to increase energy supply without increasing microbial protein supply. Steers were also abomasally infused continuously with an excess of all essential amino acids except lysine to ensure that lysine was the only limiting amino acid. Treatments were arranged as a 3 × 2 factorial with 3 additional levels of urea (0, 40, or 80 g/d) continuously infused ruminally to induce ammonia loading and 2 levels of lysine (0 or 6 g/d) continuously infused abomasally. Treatments did not affect fecal N output (P = 0.37). Lysine supplementation decreased (P < 0.01) urinary N excretion from 51.9 g/d to 44.3 g/d, increased (P < 0.01) retained N from 24.4 to 33.3 g/d, and tended (P = 0.09) to reduce plasma urea-N. Urea infusions linearly increased retained N (26.7, 28.8, and 31.1 g/d; P = 0.05) and also linearly increased (P < 0.01) urinary N excretion (31.8, 48.1, and 64.4 g/d), urinary urea (21.9, 37.7, and 54.3 g/d), urinary ammonia (1.1, 1.4, and 1.9 g/d), and plasma urea (2.7, 4.0, and 5.1 mM) for 0, 40, and 80 g urea/d, respectively. Assuming that retained protein is 6.25 × retained N and contains 6.4% lysine, the incremental efficiencies of infused lysine utilization were 51, 59, and 69% for steers receiving 0, 40, and 80 g/d of urea, respectively, suggesting that the ruminal ammonia loads might improve the efficiency of lysine utilization; this is supported by the observed increases in whole-body protein deposition in response to ammonia loading of our steers that were, by design, lysine deficient.
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Li, Hong. « Azotobacter vinelandii Nitrogenase : Multiple Substrate-Reduction Sites and Effects of pH on Substrate Reduction and CO Inhibition ». Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27608.
Texte intégralRésumé :
Mo-nitrogenase consists of two component proteins, the Fe protein and the MoFe protein. The site of substrate binding and reduction within the Mo-nitrogenase is provided by a metallocluster, the FeMo cofactor, located in the a-subunit of the MoFe protein. The FeMo cofactorâ s polypeptide environment appears to be intimately involved in the delicate control of the MoFe proteinâ s interactions with its substrates and inhibitors (Fisher K et al., 2000c). In this work, the a-subunit 278-serine residue of the MoFe protein was targeted because (i) a serine residue at this position is conserved both in the Mo-nitrogenase from all organisms examined and in the alternative nitrogenases (Dean, DR and Jacobson MR, 1992); (ii) its hydroxyl group hydrogen bonds to the Sg of the a-subunit 275-cysteine residue that directly ligates the FeMo cofactor; and (iii) its proximity to the a-subunit 277-arginine residue, which may be involved in providing the entry/exit route for substrates and products (Shen J et al., 1997).
Altered MoFe proteins of A. vinelandii nitrogenase, with the a278Thr, a278Cys, a278Ala and a278Leu substitutions, were used to study the interactions of H+, C2H2, N2 and CO with the enzyme. All strains, except the a278Leu mutant strain, were Nif+. From measurement of the Km for C2H2 (C2H4 formation) for the altered MoFe proteins, the a278Ala and a278Cys MoFe proteins apparently bind C2H2 similarly to the wild type, whereas the a278Thr and the a278Leu MoFe proteins both have a Km ten-times higher than that of the wild type. Unlike wild type, these last two altered MoFe proteins both produce C2H6. These results suggest that C2H2 binding is affected by substitution at the a-278 position. Moreover, when reducing C2H2, the a278Ala and a278Cys MoFe proteins respond to the inhibitor CO similarly to the wild type, whereas C2H2 reduction catalyzed by the a278Thr MoFe protein is much more sensitive to CO. Under nonsaturating concentrations of CO, the a278Leu MoFe protein catalyzes the reduction of C2H2 with sigmoidal kinetics, which is consistent with inhibitor-induced cooperativity between at least two C2H4-evolving sites. This phenomenon was previously observed with the a277His MoFe protein, in which the a-subunit 277-arginine residue had been substituted (Shen J et al., 1997). Together, these data suggest that the MoFe protein has at least two C2H2-binding sites, one of which may be located near the a277-278 residues and, therefore, most likely on the Fe4S3 sub-cluster of the FeMo cofactor. Like the wild type, N2 is a competitive inhibitor of the reduction of C2H2 by the a278Thr, a278Cys and a278Ala MoFe proteins. Apparently, the binding of N2 in these altered MoFe proteins is similar to that with the wild type MoFe protein, suggesting that the aSer278 residue is not directly involved in N2 binding and reduction. Previous work suggested that both a high-affinity and low-affinity C2H2-binding site were present on the MoFe protein (Davis LC et al., 1979; Christiansen J et al., 2000). Our results are generally consistent with this suggestion.
Currently, there is not much information about the proton donors and how the protons necessary to complete all substrate-to-product transformations are transferred. The dependence of activity on pH (activity-pH profiles) has provided useful information about the nature of the groups involved in proton transfer to the FeMo cofactor and the bound substrate. Approximately bell-shaped activity-pH profiles were seen for all products from catalysis by all the MoFe proteins tested whether under Ar, in the presence of C2H2 as a substrate, or with CO as an inhibitor. The profiles suggested that at least two acid-base groups were required for catalytic activity. The pKa values of the deprotonated group and protonated group were determined from the pH that gave 50% maximum specific activity. These pKa values for the altered a278-substituted MoFe proteins and the a195Gln MoFe protein under various assay atmospheres were compared to those determined for the wild type. It was found that the pKa value of the deprotonated group was not affected by either substitution or changing the assay atmosphere. The wild type MoFe protein has a pKa (about 8.3) for the protonated group under 100% argon that was not affected very much by the substitution by Cys, Ala and Leu, whereas the Thr substitution shifted the pKa to about 8, which was the same as that of the wild type MoFe protein in the presence 10% CO. The pKa values for the protonated group for all the altered MoFe proteins were not changed with the addition of 10% CO. These results suggest that the aSer278 residue, through hydrogen bonding to a direct ligand of the FeMo cofactor, is not one of the acid-base groups required for activity. However, this residue may â fine-tuneâ the pKa of the responsible acid-base group(s) through interaction with the aHis195 residue, which has been suggested (Dilworth MJ et al., 1998; Fisher K et al., 2000b) to be involved in proton transfer to substrates, especially for N2 reduction. The activity-pH profiles under different atmospheres also support the idea that more than one proton pathway appears to be involved in catalysis, and specific pathway(s) may be used by individual substrates.Ph. D.
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Bell, Ashley Lorraine. « Effects of reduced dietary protein and supplemented rumen protected amino acids on the nitrogen efficiency of dairy cows ». Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/46324.
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Dairy cows are extremely inefficient at converting dietary nitrogen (N) to productive N. Approximately 25-30% of dietary N is used for milk protein while the remaining N is lost to the environment. According to National Research Council (NRC, 2001) recommendations, dairy cow rations are formulated in terms of metabolizable protein (MP) which often causes many amino acids (AA) to be fed in excess. A better understanding of protein and AA requirements could help to improve the nitrogen efficiency of dairy cows. The objective of this work was to examine the effects of feeding a low protein diet supplemented with rumen protected (RP) AA on production and N efficiency of dairy cows. Twenty-four Holstein and 24 Holstein x Jersey crossbred cows were used in a Youden square design consisting of 3 periods. Cows were randomly assigned to one of 8 treatments: 1) a standard diet containing 17% crude protein (+Con), 2) a 15% crude protein diet (-Con), 3) â Con plus RP methionine (+M, 16g/d), 4) â Con plus RP lysine (+K, 47g/d), 5) â Con plus RP leucine (+L, 181g/d), 6) â Con plus RP methionine and lysine (+MK), 7) â Con plus RP methionine and leucine (+ML), and 8) â Con plus RP methionine, lysine, and leucine (+MKL). Cows fed the â Con as well as the +MKL diet experienced a reduction in milk production and milk protein yield (P < 0.05). Dry matter intake decreased only for those animals on the +ML diet (P < 0.05). Milk urea N (MUN) decreased for all diets when compared to the +Con treatment (P < 0.05). In accordance with the decrease in MUN, N efficiency was numerically increased in the diets supplemented with RP AA, but this improvement was not significant. Phosphorylation of signaling proteins important for protein synthesis were also examined. Animals fed the +MK treatment increased phosphorylated and total forms of eukaryotic elongation factor 2 (eEF2) when compared to the +Con and â Con (P < 0.05), but this increase in abundance did not affect the ratio of phosphorylated to total abundance. Feeding dairy cows a low protein diet supplemented with RP AA has the ability to alleviate the loss in milk production associated with feeding a low protein diet as well as to increase nitrogen efficiency.Master of Science
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Frame, Elizabeth R. « Mycosporine-like amino acids (MAAs) in bloom-forming phytoplankton : the influence of nitrogen, ultraviolet radiation and species composition / ». Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3144314.
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Lindsay, Maria. « Studies directed Towards the Iridium Catalyzed Synthesis of New Carbon-Nitrogen Bonds ». ScholarWorks@UNO, 2017. http://scholarworks.uno.edu/td/2336.
Texte intégralRésumé :
Amines are ubiquitous in nature and serve a variety of functions in living organisms. Because of this fact amines are of great biological and pharmaceutical interest. The iridium catalyst (pentamethylcyclopentadienyl) iridium dichloride dimer ([Cp*IrCl2]2) has been used in a number of ways to synthesize new carbon-nitrogen bonds. These studies were directed toward the development of a method for the iridium catalyzed N-alkylation of alpha-amino acid esters as well as the development of a strategy for synthesis of the natural product 275A.
We have optimized a method for the N-alkylation for alpha-amino acid esters. Using this method, we have N-alkylated a series of alpha-amino acid esters with a variety of alcohols. We have shown that the N-alkylation of the alpha-amino acid esters works consistently and gives the desired products in moderate to high yields. We have examined the effect of this method on the chiral center of the obtained products by analyzing their optical rotation. Evaluation of these specific rotations indicated racemization was occurring but it is believed that any loss of the chiral center is due to the reaction conditions.
Amphibian alkaloids are of great interest to the pharmaceutical and academic communities due to their biological activities. Unfortunately, they are not naturally available in large quantities which makes total synthesis the most common method of generating these compounds for evaluation. One amphibian alkaloid class of interest to us are the Lehmizidines. These are bicyclic ring structures consisting of a 7-member and 5-member ring with a nitrogen bridgehead. The alkaloid, 275A, was selected as a target for a general synthetic approach. This synthetic approach required the synthesis of novel diols. The construction of these diols along with a method for the synthesis of the azepane ring is presented here.
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Xu, Peng. « Asymmetric Synthesis of Nitrogen Containing Bioactive Compounds via the Utilization of Enantiopure p-Toluenesulfinimines ». Diss., Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/216585.
Texte intégralRésumé :
ChemistryPh.D.
The research objective of this thesis research was to develop new methods for the asymmetric synthesis of amine derivatives using p-toluenesulfinimines. Enantiopure sulfinimines are versatile chiral building blocks for the asymmetric synthesis of alkaloids. Sulfinimines were prepared by the condensation of (S)- or (R)-p-toluenesulfinamide with aldehydes and ketones in good to excellent yields, which were prepared from the commercially available Anderson reagent. The first research project was the development of a new method for the preparation of enantiopure anti-anti- α-lkyl β-amino ketones and was accomplished by the stereoselective α-alkylation of enolates of sulfinimine derived β-amino esters. The anti- α-lkyl β-amino esters were transformed to their corresponding Weinreb amides by reacting with lithium dimethyl hydroxyl amine without epimerization. Reactions of the Weinreb amides with Grignard and organolithium reagents afforded the corresponding anti- α-lkyl β-amino ketones in modest yields and high optical purity. The modest yields are the results of competition between addition and reduction of the Weinreb amide. anti- α-lkyl β-amino ketones are important chiral building blocks for the asymmetric synthesis of nitrogen-containing biologically active molecules, such as pyrrolidines, piperidines and other alkaloids. To further illustrate the utility of sulfinimine -derived enantiopure N-sulfinyl anti- α-lkyl β-amino ketones, they was applied to the asymmetric synthesis of the unknown anti-C5, C6 derivative of 2,3,4,6-tetrasubsituted indolizidine 221-T. The key step in the synthesis was the stereoselective construction of the piperidine ring of the 5,6,8-tri-substituted indolizidine and was realized via the use of an acid-catalyzed intramolecular Mannich cyclization. The indolizidine was readily transformed in to the key intermediate 7-hydroxyl-2,3,4,6-tetrasubsituted indolizidine in high stereoselectivity and yield. Changing the sequence of chemical operation steps avoided the production of the side product β-pyrrole ketone. Reduction of the intermediate piperdinone, followed by ring-closing metathesis and reductive catalytic hydrogenation afford the bicyclic indolizidine with overall 76% yield of 3 steps. The C-2 branched cocaine analogs are thought to have varied bioactivities and potent therapeutical uses compared to other positions of substituted cocaine analogs. However, reports on the synthesis of such analogs are few. The first example of preparation of a cocaine analog having a dimethylphosphonate group at the C-2 position was reported. The key step in forming the required isoxazolidine intermediate, which controls the required cis stereochemistry at C-2 and C-3, was a novel microwave induce stereoselective [3+2] intramolecular cycloaddition of an α,β-unsaturated pyrrolidine nitrone. The use of the microwave irradiation techniques significantly reduce the time required for isoxazolidine formation from 96 hours to five hours.
Temple University--Theses
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Camargos, Liliane Santos de. « Alterações no metabolismo de compostos nitrogenados em Calopogonium mucunoides em resposta a diferentes fontes de nitrogênio : efeitos na nodulação e na fixação ». [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315648.
Texte intégralRésumé :
Orientador: Ladaslav SodekTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Calopogonium mucunoides é uma leguminosa tropical típica de cerrado, sendo muito utilizada em adubação verde e como forrageira. Possui alta capacidade de fixação de nitrogênio, sendo cultivada em solos de baixo pH e pouca fertilidade; e boa resistência à seca, mas não tolera baixas temperaturas. Poucos são os estudos acerca do metabolismo de nitrogênio nesta espécie, mas demonstram que a leguminosa apresenta alta abundância relativa de ureídeos quando fixando nitrogênio. Estudos preliminares nossos demonstraram certa tolerância do mecanismo de fixação à exposição ao nitrato. Este trabalho objetivou estudar o metabolismo de nitrogênio, em Calopogonium mucunoides, identificando as principais alterações no metabolismo de nitrogênio sob diferentes condições de obtenção deste nutriente: plantas cultivadas recebendo solução nutritiva com diferentes fontes de nitrogênio antes da nodulação; e plantas plenamente noduladas, então expostas a receber solução nutritiva com diferentes fontes de nitrogênio, em diferentes concentrações e por diferentes tempos de exposição. Observou-se que a espécie não apresentou nodulação sensível à presença de nitrogênio no meio e, quando plantas plenamente noduladas foram expostas ao nitrogênio, a fixação foi mantida e a atividade da enzima nitrogenase só foi afetada, embora não totalmente, quando as plantas foram expostas a concentrações de 30 mM de nitrato. Por outro lado, a espécie parece responder à fonte de nitrogênio translocando e/ou acumulando diferentes formas de ureídeo (alantoína e ácido alantóico), mas o metabolismo de aminoácidos não apresentou resposta padrão à exposição ao nitrogênio. Estes estudos indicaram tolerância da nodulação e da fixação de nitrogênio desta espécie ao cultivo na presença de nitrogênio, podendo então servir de embasamento a futuros estudos acerca da sensibilidade/tolerância desses processos à presença de nitrogênio no meio em leguminosas em geral
Abstract: Calopogonium mucunoides is a tropical legume found in the ¿cerrado¿ (savanna) regions, and widely used as green manure and forage. It has a high capacity for fixing nitrogen, being cultivated in soils with low pH and poor fertility; and good resistance to drought, but does not tolerate low temperatures. Studies on the nitrogen metabolism of this species are quite scarce but it is known that the legume has a high relative abundance of ureides when fixing nitrogen. Our own preliminary studies suggested certain tolerance of fixation to the presence of nitrate. The objective of the present study was to study nitrogen metabolism in Calopogonium mucunoides, identifying the influence of the nitrogen source on nitrogen metabolism using: different nitrogen sources starting before nodulation; and exposing plants to the same sources only after complete nodulation, at different concentrations and times of exposure. It was found that the nodulation process of this species was not sensitive to the presence of a nitrogen source in the medium and, when fully nodulated plants were exposed to the nitrogen sources, fixation was maintained and the activity of nitrogenase was only affected, albeit partially, when exposed to the highest (30 mM) dose of nitrate. On the other hand, the species appears to respond to the exogenous source of nitrogen by translocating and/or accumulating different forms of ureides (allantoin and allantoic acid), but the metabolism of amino acids did not respond clearly to the nitrogen source. The data indicate that the process of nodulation and nitrogen fixation in this species is tolerant to the presence of a nitrogen source in the medium and should prove useful for future studies on the sensitivity/tolerance of nitrogen fixation to na external nitrogen source in legumes
Doutorado
Doutor em Biologia Vegetal
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MURATORE, CHIARA. « CHARACTERIZATION OF PROTEOMIC CHANGES IN CROPS DURING METABOLIC ADAPTATION TO DIFFERENT NITROGEN INPUTS ». Doctoral thesis, Università degli Studi di Milano, 2023. https://hdl.handle.net/2434/951273.
Texte intégralRésumé :
Nitrogen availability is one of the major factors that influence plant growth, morphology, and metabolism and, hence, crop productivity. In agricultural soils, nitrogen is present in different forms, both inorganic (nitrate and ammonium) and organic (amino acids, short peptides and urea), with variable and heterogeneous distribution. Nowadays, improving knowledge about the nitrogen nutrition in plants is crucial to address the urgent need for a more sustainable agricultural production. In the last years, the “-omics” approaches provided a holistic perspective of the molecular mechanisms underlying plant metabolic adaptations to different nitrogen inputs. Among these, proteomics was largely and successfully applied to analyze various aspects, including the role of post-translational modifications and enzyme isoforms. The aim of this PhD project was to obtain new insights about the biochemical events during sensing and adaptation to different availabilities of nitrogen forms in crops, through an approach based on the integration of physiological, metabolic and proteomic evaluations.
The first research activity consisted in an extensive literature revision about plant nitrogen nutrition and plant proteomics, which led to the publication of a review article. This activity highlighted that the majority of the information derives from studies conducted in Arabidopsis and in model crops, such as maize, rice and tomato. Nevertheless, analogies and peculiarities remain to be verified in other crop species. For instance, nitrogen nutrition has been only slightly investigated in perennial plants, and proteomics has been rarely applied in this context. At the same time, although in herbaceous species great progress has been made in understanding plant metabolic responses to inorganic nitrogen forms, several aspects await a clear elucidation. A representative case consists in the fact that a clear overview of the role of specific subcellular compartments during nitrate and/or ammonium nutrition is still fragmentary. Moreover, the literature revision pointed out an increased interest in understanding the relevance of organic nitrogen forms as nutrients influencing plant growth and development. Although it is recognised that plants are able to take up organic forms of nitrogen, such as amino acids, their actual contribution to plant nitrogen nutrition is currently unknown. Starting from these considerations, during the PhD three studies have been designed and conducted, leading to the publication of an article and the preparation of two manuscripts.
The first study was devoted to the analysis of nitrogen metabolism in a perennial woody species. In particular, it was aimed at investigating the biochemical and proteomic responses to nitrate in a grapevine rootstock genotype. Indeed, even though grapevine has been adopted as a model perennial species, little is known about the biochemical roles played by roots in nitrogen acquisition. Moreover, this topic has never been addressed through a proteomic approach.
The aim of the second study was to deepen the knowledge about the responses to nitrate, ammonium or their co-provision in maize seedlings, adopting a novel proteomic approach. Specifically, key proteins involved in these biochemical mechanisms are localized in different cellular compartments and their functionality is deeply affected by the kind of inorganic source. Hence, a subcellular proteomic approach was applied to obtain new insights about the roles of distinct organelles in the ability of roots to manage different inorganic nitrogen availabilities.
Finally, the third study aimed to investigate whether maize plants are able of using and metabolizing amino acids as nitrogen source, when they were externally supplied as a mixture that mimics soil conditions. Considering the complexity of the amino acid metabolism in plants, the application of a proteomic approach was chosen as a useful holistic strategy to obtain a comprehensive overview and to gain new information. In particular, the physiological, biochemical and proteomic changes in roots and leaves were compared to those associated with nitrate availability as a reference inorganic nitrogen source.
Overall, these studies provide novel information about how plants perceive and adapt to different nitrogen availabilities. According with the literature, nitrate influenced several aspects acting as either a nutrient, an osmolyte and a signal molecule. In addition, it has been possible to highlight that, in comparison to herbaceous species, specific responses to nitrate occurred in grapevine. Moreover, the subcellular proteomic investigation allowed to appreciate how nitrate and ammonium have different, and sometimes contrasting, effects on the cell organelles functionalities, especially with regard to mitochondria and vacuoles. Finally, new hints about the metabolic pathways involved in amino acid-based nutrition were provided. In particular, the provision of amino acids to the maize plants impacted on the carbon and energy metabolism in roots and influenced the translocation of amino acids to shoot.
In conclusion, these studies confirm that the different nitrogen sources have distinct and significant effects on plant growth and physiology, and also put in evidence some interesting peculiarities related to plant species and developmental stages. Moreover, they underline the key role of roots in response to nitrogen forms, providing new evidence that amino acid metabolism represents a key point in the carbon/nitrogen balance in plants.
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Strengbom, Joachim. « Nitrogen, parasites and plants : key interactions in boreal forest ecosystems ». Doctoral thesis, Umeå universitet, Ekologi och geovetenskap, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-111110.
Texte intégralRésumé :
In the work described in this thesis I studied how increases in nitrogen (N) inputs may affect plant community structure in boreal forest understorey vegetation. These phenomena were investigated in N fertilization experiments and along a national N deposition gradient. After five years of N additions, large changes in understorey vegetation composition were observed in the fertilization study. In plots that received 50 kg N ha'1 year"1 (N2), the abundance of the dominant species, Vaccinium myrtillus, decreased on average by 32 %. No decrease was observed in control plots during the same period. In contrast, the grass Deschampsia flexuosa responded positively to increased N input, being on average more than five times as abundant in the N2 treatments as in controls. Also an increase was seen in the incidence of disease caused by the parasitic fungus Valdensia heterodoxa on leaves of V. myrtillus following N additions. The parasite was on average nearly twice as abundant in N2 plots than in control plots. This could be explained by increased N concentrations in host plant tissue. Disease incidence also increased following experimental additions of glutamine to leaf surfaces of V. myrtillus, suggesting a causal connection between plant N concentration and performance of the fungus. The parasite also played a key role in the observed changes in understorey species composition. D. flexuosa was more abundant in patches in which V. myrtillus was severely affected by V heterodoxa. This suggests that V heterodoxa mediates the increased abundance of D. flexuosa following increased N additions. The fungus mediates changes in the composition of understorey vegetation mainly by increasing light availability via premature leaf loss of V. myrtillus. The incidence of disease due to the parasite was on average higher in large than in smaller N-treated plots, indicating that the response to N fertilization is spatially scale dependent. This shows that using small plot sizes in experiments that simulate changed environmental conditions may be problematic, as important interactions may be underestimated. Comparison of the occurrence of understorey species between regions with different rates of N deposition revealed that the occurrence of the two dwarf shrubs V. myrtillus and V. vitis- idaea was lower in regions with high N deposition compared to regions with low deposition. The opposite pattern was found for V heterodoxa. This is consistent with expectations from N fertilization experiments. For D. flexuosa no differences in occurrence were found between the different regions investigated. The effects on vegetation and mycorrhizal fungi observed following N additions were also found to be long lasting. Nine years after termination of the fertilization, no signs of recovery were detected, and nearly 50 years after termination characteristic signs of N fertilization were found among bryophytes and mycorrhizal fungi. This suggests that the time needed for re-establishment of the original biota following N-induced changes may be substantial.Diss. (sammanfattning) Umeå : Umeå universitet, 2002, härtill 5 uppsatser
digitalisering@umu
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Lantos, Susanne Debora. « Hydrogen bonding between tetraphenylborate anions and nitrogen-containing cations, and a novel amine-borane compound ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ36487.pdf.
Texte intégral
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Boudreau, Thomas F. IV. « The Effect of Fungicide Residues and Yeast Assimilable Nitrogen on Fermentation Kinetics and H2S Production during Cider Fermentation ». Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/81452.
Texte intégralRésumé :
The Virginia cider industry has grown rapidly in the past decade, and demands research-based recommendations for cider fermentation. This study evaluated relationships between the unique chemistry of apples and production of hydrogen sulfide (H2S) in cider fermentations. Yeast assimilable nitrogen (YAN) concentration and composition and residual fungicides influence H2S production by yeast during fermentation, but these factors have to date only been studied in wine grape fermentations. This study surveyed 12 Virginia-grown apple cultivars and found that the majority were severely deficient in YAN. The effects of three fungicides on cider fermentation were investigated; elemental sulfur, fludioxonil and fenbuconazole. Fenbuconazole adversely impacted fermentation kinetics. Sulfur and fludioxonil marginally impacted fermentation kinetics. Sulfur increased H2S production, but fludioxonil and fenbuconazole did not affect H2S production. There was no difference in fermentation kinetics and H2S between nitrogen sources arginine (approximating grape), asparagine (approximating apple) and ammonium (YAN supplement). Supplementation with methionine resulted in increased fermentation rate and decreased H2S production. The detrimental effects of fenbuconazole and beneficial effects of methionine were diminished with increasing total YAN. Contrary to previous findings, the most H2S was formed at 153 mg/L YAN which is above the generally recommended minimum to prevent H2S formation. These results indicate that apple juice chemistry may influence yeast metabolism during cider fermentation, in ways that have not been previously studied in grape fermentation. Our findings indicate the need for and contribute to the development of targeted fermentation management practices for cidermaking.Master of Science in Life Sciences
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Heffron, Sean Patrick. « The Effect of Whey Protein Isolate on Plasma Amino Acids, Nitrogen Balance, Glutathione and Performance during Energy Restriction in Athletes ». Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/41336.
Texte intégralRésumé :
This study compared the effects of whey and casein on plasma AA, nitrogen balance (NBAL), glutathione and performance in dieting athletes. Twenty cyclists consumed 40 g·d-1 whey (WHEY) or casein (CAS) for 3 wk. On d 18 – 21 subjects restricted intake to 20 kcal·kg-1·d-1 plus protein supplement. Apparent NBAL was estimated on d 18 – 21 while postabsorptive and 2 h postprandial plasma AA were measured on d 14 and 21. On d 1, 15 and 22 subjects performed an exercise performance test and provided blood for glutathione analysis. Both groups experienced similar negative NBAL (CAS = -19.7 ± 1.4 g, WHEY = -21.4 ± 2.7 g) during energy restriction. There were trends towards a reduction in performance during energy restriction (p = 0.073) and an interaction of group with day (p = 0.072). There were significant main effects of state (postabsorptive = 34.5 ± 2.4 µM, postprandial = 37.1 ± 3.0 µM; p = 0.038) and day (d 14 = 33.8 ± 2.2 µM, d 21 = 37.8 ± 3.2 µM; p = 0.008) on plasma cysteine. There was a significant interaction of state and day on glutamine (p = 0.002), as levels increased 1.3% from postabsorptive to postprandial measurements on d 14, but decreased 4.2% on d 21. The absolute change in postabsorptive cysteine from d 14 to d 21 was correlated with NBAL (r = 0.766, p = 0.01) in CAS but not in WHEY. Plasma glutamine did not correlate with NBAL in either group.Master of Science