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1
Poole, Philip. "Amino acid metabolism in Rhizobium." Thesis, Poole, Philip (1986) Amino acid metabolism in Rhizobium. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/51728/.
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Addition of a broad range of L-amino acids and several D-amino acids to washed cells of Rhizobium leguminosarum strains WU235 and MNF3841 grown on glucose/NH4Cl elicited a low rate of O2 consumption. L-Glutamate, L-glutamine, L-aspartate, L-asparagine, L-alanine or L-histidine served as the sole source of nitrogen and carbon for growth of strain WU235 and each caused a several-fold increase in the amino acid dependent O2 consumption. In all these cultures excess ammonia was liberated, with the quantity depending on the number of nitrogen atoms per amino acid molecule. A very high dicarboxylic acid dependent O2 consumption in cells of WU235 grown on aspartate was found to be due to the presence of aspartase (EC 4.3.1.1).
R. leguminosarum WU235 only expressed aspartase when grown on L-aspartate or L-asparagine as the sole carbon source. Cells grown on glucose plus L-aspartate, or fumarate plus L-aspartate, did not express aspartase. Although these results suggested catabolite control of an inducible enzyme, induction of aspartase could not be demonstrated. Aspartase-producing cells continued to synthesize the enzyme after repeated subculture on glucose plus NH4Cl. Cells grown in glucose plus NH4Cl and plated onto aspartate produced different colony sizes; the larger (0.1% of the total) expressed aspartase, while the smaller did not. At dilutions sufficient to exclude the large aspartase-producing colonies, all initial colonies were the same size. They later developed papillae or became cluster colonies and produced aspartase. The data suggest that strain WU235 is unable to produce aspartase unless a mutation occurs which leads to constitutive enzyme synthesis.
Rhizobium leguminosarum MNF3841 grown on glucose/NH4Cl constitutively transported several L-amino acids. Transport rates were elevated 1.5-4 fold after growth in the absence of anmonia. Uptake of L-glutamate, L-glutamine, L-asparagine and L-leucine was inhibited to varying extents by a broad range of L-amino acids. The use of structural analogues of Lglutanvate and metabolic inhibitors suggested that L-glutamate transport was an active process requiring the L-isaner to have a free alpha hydrogen and a free amino group. Cells loaded with either L-(14C) leucine or L-(14C) glutamate exhibited exchange with a wide range of amino acids. The apparent Km for L-glutamate transport was 81 nM and both Laspartate and L-alanine were competitive inhibitors of Lglutamate uptake. Thus there appears to be an extremely high affinity carrier for L-glutamate that is not only very sensitive to inhibition by L-aspartate but also capable of being inhibited by a broad range of amino acids at an order of magnitude higher concentration.
Batch cultures of R. leguminosarum MNF3841, R. leguminosarum WU235, R. phaseoli WU15, R. trifolii TA1 and R. meliloti WU38 used amnonia faster than glutamate when presented with an equimolar mixture of the two. Only the cowpea strain NGR234 used both nitrogen sources at the same rate. R. leguminosarum MNF3841 grew faster on ammonia than on glutamate as the nitrogen source. In chemostat culture grown under phosphate limitation strain MNF3841 did not release excess ammonia when grown on either mannitol/L-glutamate or fumarate/L-glutamate, showing that L-glutamate catabolism was tightly regulated to meet the cells nitrogen requirement. Furthermore the rate of consumption of ammonia was similar to that for L-glutamate when either was supplied as the sole nitrogen source. However with L-histidine or L-alanine as the nitrogen source large quantities of excess ammonia were released. When chemostat cultures of R. leguminosarum MNF3841 were supplied with an equimolar mixture of ammonia and Lglutamate, 81-100% of the nitrogen consumed was ammonia. Similarly with mixtures of L-glutamate/L-histidine or Lglutamate/ L-alanine almost no L-glutamate was consumed, a result attributable to the release of excess ammonia from either L-histidine or L-alanine. The use of 14C labelled fructose or L-glutamate suggested that the intra and extracellular L-glutamate pools were isolated. This indicated that the ammonia preference must be exerted by a restriction in Lglutamate transport. L-Glutamate transport rates were low in L-glutamate/NH4Cl containing chemostats, which suggests ammonia restricts L-glutamate transport both by repression and perhaps by inhibition by seme metabolic intermediate.
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Ebikeme, Charles E. "Amino acid transporters and amino acid metabolism in trypanosoma brucei brucei." Connect to e-thesis, 2007. http://theses.gla.ac.uk/55/.
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Thesis (Ph.D.) - University of Glasgow, 2007.Ph.D. thesis submitted to the Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, 2007. Includes bibliographical references.
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Ebikeme, Charles E. "Amino acid transporters & amino acid metabolism in Trypanosoma brucei brucei." Thesis, University of Glasgow, 2007. http://theses.gla.ac.uk/55/.
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The development of new drugs against Human African Trypanosomiasis is much needed due to toxicity, efficacy and availability problems with current drug treatments for this resurgent parasitic disease. Delivery of drugs into cells is an important determinant of therapeutic efficacy of drugs. An effective means of selective drug delivery is to use plasma membrane transport systems to mediate the entry of drugs into the cell. Some amino acid transporters fulfil the criteria needed for successful exploitation of nutrient transport systems for drug delivery. The Trypanosoma brucei genomic database was screened to identify the full gene repertoire of amino acid transporters. From this, candidate genes were selected and functional genetic approaches were employed to characterise candidate amino acid transporter genes. Further characterisation of TbAATP1, a RNAi cell line shown to be a transporter of small neutral amino acids (serine, glycine, cysteine, asparagine and alanine), showed a role in threonine uptake. Amino acid analogues were tested for trypanocidal activity. Of the 96 tested, two (Azaserine and Levodopa) were investigated in more detail, paying special attention to the nature of their trypanocidal action and possible route of entry through an amino acid transporter. Azaserine showed a trypanostatic action as well multiple routes of entry into the protozoan interior (as shown by inhibition of glutamine, phenylalanine and tyrosine uptake). The trypanocidal Levodopa showed entry through a tyrosine specific transporter. However, it is possible that Levodopa’s trypanocidal activity may not be as a result of the analogue itself, but secondary products of the analogue. Amino acids are important for protozoa as energy sources as well as forming pools of soluble osmolites. Amino acid usage in trypanosomes was investigated. Upregulation of proline transport and catabolism in response to reduced glucose availability was exhibited by the genome strain of T. brucei. Moreover, this metabolic shift could be mimicked by addition of GlcNAc to the medium, which blocks the hexose transporter limiting glucose entry to the cell. Systems biology approaches were initiated to investigate the undergoing metabolic changes. More specifically, mass spectrometry methodologies were employed to investigate underlying metabolite changes in procyclic form trypanosomes grown in differing medium.
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Cooper, Leah. "Nonessential amino acid metabolism in humans." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52641.
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Nutritionally, there is a dietary requirement for the essential amino acids (EAA) but also a requirement for nitrogen (N) intake for the de novo synthesis of the nonessential amino acids (NEAA). It has been suggested that some NEAA may be more metabolically important than others. The first study (Glutamate Requirement Study) aims to examine the application of the indicator amino acid oxidation (IAAO) technique to determine if a dietary requirement for glutamate exists in adult humans. The second study (NEAA Study) aims to determine the metabolic demand of nine of the NEAA (Ala, Arg, Asn, Asp, Gln, Glu, Gly, Pro, Ser) as an ideal N source using the IAAO technique.
Seven subjects were maintained on an adaptation diet for 2 days prior to each test day. Each subject participated in two or eleven test diet intakes, assigned randomly, in the glutamate study and the NEAA study, respectively. In the glutamate study, the diets corresponded to the amino acid pattern present in egg protein, in which all glutamate and glutamine was present as glutamate, or removed, with serine used to make the diets isonitrogenous. In the NEAA Study, one test intake was a base diet consisting of only the EAA provided at the recommended dietary allowance. All other test intakes involved the base diet with the addition of one NEAA to meet a 50:50 ratio of EAA: NEAA on a N basis. Each study day followed the IAAO protocol using L-[1-¹³C]-Phenylalanine as the indicator. Breath and urine samples were collected at baseline and isotopic steady state. Enrichments of ¹³C in breath were analyzed by isotope ratio mass spectrometry to calculate F¹³CO₂.
In the glutamate study, a paired-samples t-test did not find a significant difference between the F¹³CO₂ in response to the two glutamate intakes. In the NEAA study, repeated measures ANOVA with post hoc multiple comparisons showed that seven of the nine NEAA decrease IAAO significantly. Thus the results suggest that in healthy adults, there is no dietary requirement for glutamate, and that most NEAA are good N sources, in the presence of adequate EAA.Medicine, Faculty of
Medicine, Department of
Experimental Medicine, Division of
Graduate
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Wang, Alice Chun-Yin. "Amino acid metabolism in the inflammatory niche." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28572.
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Stroma and parenchyma represent the supportive and functional components in every organ of the body, respectively. Beyond their ability to produce structural support and to differentiate into tissues of mesodermal origin, mesenchymal stromal cells (MSC) exhibit potent immunomodulatory properties. Such a function requires an activation step ('licensing signal') provided by the inflammatory microenvironment to which MSC are exposed. My results have attributed immunosuppressive effects of MSC to essential amino acid (EAA) deprivation. Amongst the EAA consuming enzymes examined, blocking nitric oxide synthase 2 (NOS2) and histidine decarboxylase (HDC) both resulted in impaired anti-proliferative activity of MSC, while NOS2 appeared to be a more prominent effector. My results have also demonstrated that TNF-α and IFN-γ differently account for NOS2 and HDC up-regulation, respectively. Furthermore, MyD88 and NF-κB were identified as upstream mediators for initiating NOS2 production. The role of TNF-α and NOS2 in MSC-mediated immunosuppression was assessed in vivo using a murine model of peritonitis. MSC treatment remarkably reduced the local inflammatory response during acute peritoneal inflammation. Nevertheless, both Nos2-/- and Tnfr1/r2-/- MSC delivered similar effects compared to WT MSC, indicating the presence of other complementary mechanisms in MSC-mediated immunosuppression in vivo. In addition to their immunomodulatory properties, MSC are fundamental in regulating self-renewal and differentiation of haematopoietic stem cells (HSC). MSC protect HSC from potential damage by maintaining their quiescence. My results have revealed that the ability of MSC to enhance the quiescence of HSC was associated with cell-cycle arrest induced by NOS2. As striking parallels exist between the normal and malignant stem cell niche, I investigated the ability of MSC to protect haematopoietic malignant cells from chemotherapy-induced apoptosis. MSC were observed to confer protection from etoposide-induced necrosis of EL4 cells, possibly due to their ability to suppress EL4 proliferation. Collectively, my results have demonstrated the role of MSC across the fields of immunomodulation, niche-supporting and anti-apoptotic effects.
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Hou, Chunsheng 1968. "Sulfur amino acid catabolism in a piglet model." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=78381.
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A model was developed in growing piglets to study the use of urinary total sulfur excretion as an indicator of sulfur amino acid (SAA) catabolism and the nitrogen (N)/sulfur (S) balance ratio as an indicator of non-protein SAA storage. The recovery of administrated methionine as urinary total S over 48 hours was 106% in well-nourished piglets, but only 69% in protein malnourished piglets. The N/S balance ratio of protein malnourished piglets was lower than that of well-nourished piglets, and this ratio further decreased after methionine administration. We conclude that in a protein malnourished state, relatively more S than N is retained and a significant portion of the S derived from administrated methionine is retained in non-protein pools. These results demonstrate that urinary total S excretion can provide an accurate measure of SAA catabolism; and the N/S balance ratio can provide valuable information about non-protein SAA storage in growing piglets.
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Sharer, Nicholas M. "Sulphur amino acid metabolism, oxidative stress and pancreatitis." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396793.
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Lee, Edward Robert. "Investigations related to branched-chain amino acid metabolism." Thesis, University of Warwick, 1989. http://wrap.warwick.ac.uk/99899/.
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A novel synthetic route to heterogeneous acyloins was developed using benzothiazole/thiazolium species. The synthetic route mimics the biological action of thiamine pyrophosphate (TPP) in acetohydroxyacid synthase, the first enzyme of the valine-isoleucine biosynthetic pathway. The synthetic intermediates were examined by x- ray crystallography. Racemic [3,4-13C2]-α-acetolactate was synthesised. Treatment of the 13C-labelled α-acetolactate with acetolactate decarboxylase and analysis of the subsequent reactions by Hnmr showed that the enzyme rapidly decarboxylated the S-isomer to give [l,2-13C2]-3-hydroxy-butan-2-one and the R-isomer underwent an enzyme catalysed tertiary ketol rearrangement and then decarboxylation to yield [3,4-13C2]-3- hydroxybutan-2-one. The stereochemistry of a base-catalysed tertiary ketol rearrangement was investigated. R-α-acetohydroxybutyrate was treated with alkali and the resulting products were analysed by reaction with acetolactate decarboxylase. It was found that there is a preference for a syn-conformation of the C-0 bonds during the carboxylate ion migration. A novel sixteen step synthesis of methyl α-acetolactate with a chiral methyl group at the α-position was developed. Chemical syntheses of intermediates of the valine-isoleucine biosynthetic pathway were developed, including the attempted synthesis of trifluoromethyl-analogues. High field ‘Hnmr techniques were used to investigate directly the reactions catalysed by AHAS isoenzyme 2 (Salmonella tvphimurium) and AHAS isolated from pea plants. The ‘Hnmr investigations permitted the analogous reactions catalysed by AHAS to be studied and gave an insight into the nature of the reactions occurring at the enzyme active site.
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Brown, Toby James Neville. "Analytical studies of some amino acid secondary metabolism." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300806.
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Hawkey, Robin Keith. "Amino acid oxidation and protein metabolism in animals." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334760.
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Salter, M. "Aromatic amino acid metabolism in the rat liver." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374780.
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Smith, Elizabeth Anne. "Dissimilatory amino acid metabolism by human colonic bacteria." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627591.
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Mutsvangwa, Timothy. "Studies of amino acid metabolism in isolated sheep hepatocytes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24419.pdf.
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Eijk, Hendrikus Maria Hubertus van. "Analytical aspects to the study of amino acid metabolism." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 1999. http://arno.unimaas.nl/show.cgi?fid=6843.
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Dubbelhuis, Peter Foeke. "Regulation of metabolism by amino acid dependent signal transduction." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/75780.
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Kyriakopoulos, Sarantos. "Amino acid metabolism in Chinese hamster ovary cell culture." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25143.
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The present thesis focuses on amino acids (a.a.) and their metabolism by Chinese hamster ovary cells, the workhorse of the multibillion dollar biopharmaceutical industry. The aim of the research was to explore a.a. transport and metabolism and define optimal operating conditions during fed-batch culture, which is the most common process mode used industrially. A fast and reliable way to calculate a.a. concentration ranges in media and feeds is of vital importance, as a.a. are the monomers of proteins, which account for 70% of dry cell weight. The desired recombinant product of bioprocesses is typically also a protein. The transport of a.a. into the cells was studied at the mRNA level of a.a. transporters for the first time in a bioprocessing context. The presented results demonstrate that a.a. transport is not the limiting step for recombinant protein formation. Also, the study allowed for a staged feeding strategy to be designed, where a.a. were not fed altogether. Following linear projection of an integral of viable cell concentration target and using the specific a.a. consumption rates during batch culture, six feeds were formulated containing a.a. and glucose. Three designs were based on the results of the a.a. transport study; however, they underperformed in comparison to the other feeds. In the latter, all nutrients were fed at the same time, resulting in cell culture performance comparable to that obtained with a commercial feed that was tested in parallel. This renders the presented method the first to define a traceable quantitative way to calculate amount of nutrients in the feeds. Flux balance analysis, a powerful technique that allows for investigation of intracellular dynamics, was used to analyse the metabolic data. An enhanced intracellular network was created by coupling two pre-existing in the literature that also for the first time included the glycosylation of the host proteins in the biomass equation. Finally, a novel methodology was developed and coded in R to calculate specific rates of consumption/production of various metabolites in cell culture. The methodology couples mass balances for fed-batch culture operation with constructed vectors of the sampling and feeding schemes. This can be further developed to a bioprocess relevant software platform for analysing cell culture data.
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Myers, Adelyn. "Modeling post absorptive amino acid metabolism in dairy cattle." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/95890.
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The purpose of this research was to evaluate four objectives: 1) update and evaluate predictions of essential amino acid (EAA) outflows from the rumen, 2) predict EAA use and release by the portal drained viscera (PDV) and liver (LIV) of dairy cows, 3) predict EAA use by the mammary (MAM) and non-splanchnic, non-mammary (OTH) tissues, and 4) predict milk protein production from MAM use. To evaluate the first objective, a model was constructed using previously derived equations for ruminally undegraded (RUP), microbial (MiP) and endogenous protein (EndP) flow from the rumen and refit to literature data. Corrections were included in the model to address recovery of EAA during 24-h acid hydrolysis. Upon initial evaluation, all EAA, except Leu, were over predicted and slope bias (P < 0.01) was present for all except Met and Leu. Because of the bias, residuals were regressed on the EAA from each protein flow and adjustments were made to the protein flows. The added adjustments removed all mean bias for the EAA; however, a small slope bias was introduced for Lys and Thr. To evaluate the second objective, equations of Hanigan et al. (2004b) were tested and modifications were made to determine which equation form best represented EAA use by the tissue. Upon initial evaluation of the PDV model of Hanigan et al. (2004b), significant slope bias was present and addressed by deriving alternative forms of the equation. Initial predicted EAA use displayed a mean bias ranging from 0.15 to 45 % and a slope bias ranging from 0.02 to 76% mean square error. The alternative equation forms derived reduced the overall mean and slope bias and improved other fit statistics (RMSE, CCC). To evaluate the third objective, previously derived equations from Hanigan et al. (1998b) were tested using literature data and modifications were made to address deficiencies for each EAA. Upon initial evaluation of the MAM model, significant mean and slope bias was present and was further addressed by derivation of alternative equation forms. Initial evaluation of the OTH model displayed significant mean and slope bias for majority of the EAA ranging from 0.3 to 26 % for mean and 46 to 61 % for slope. For the last objective, several models, both linear and non-linear were evaluated to determine which EAA have a significant impact on milk protein. All models derived has prediction errors below 18-20 % which is comparable or a s light improvement as compared to previous literature data (Moraes et al., 2018). Overall, the equations evaluated show promise in accurately predicting dietary EAA from the time of absorption to their use within the tissues (PDV, LIV, MAM, and OTH) and further impact on milk protein production.
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Uo, Takuma. "Enzymological Studies of D-Amino Acid Metabolism in Eucaryotes." Kyoto University, 2001. http://hdl.handle.net/2433/150758.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第8986号
農博第1168号
新制||農||819(附属図書館)
学位論文||H13||N3505(農学部図書室)
UT51-2001-F316
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 江﨑 信芳, 教授 清水 昌, 教授 天地 輝夫
学位規則第4条第1項該当
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Pérez, Martí Albert. "The role of FGF21 in the metabolic response to amino acid restriction." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/401895.
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Obesity and associated metabolic diseases have reached epidemic proportions, affecting not only high-income countries but also low- and middle-income ones. In this context, the search for therapeutic approaches to treat obesity is becoming a priority worldwide.
In this regard, the metabolic hormone fibroblast growth factor 21 (FGF21) has been identified as a potential candidate for the treatment of obesity and metabolic syndrome. Previous work by our group described that FGF21 is highly induced in liver in response to leucine deprivation and that the transcription factor ATF4 mediates this induction. The present work is the follow-up of this initial observation.
To delve deeper into the molecular mechanisms that regulate FGF21 expression during leucine deprivation, we focused on the transcriptional repressor Rev-erbα, which functions both as a core repressive component of the cell autonomous clock and as a regulator of metabolic genes.
Our results reveal a consistent negative correlation between Fgf21 and the Pgc-1α/heme/Rev-erbα axis across various nutritional states and that a decrease in Rev-erbα activity enhances the ATF4-mediated upregulation of the human FGF21 promoter. Consequently, we propose a model whereby the induction of Fgf21 upon leucine deprivation is the consequence of the sum of two factors: binding of the activator ATF4 to the promoter and the absence of the repressor Rev-erbα.
Given the coincidence between the effects of leucine deprivation and those observed during FGF21 treatment, we analysed the role of FGF21 during leucine deprivation. In the current study, we demonstrate that weight loss, downregulation of key lipogenic genes in liver and WAT, and BAT activation in response to leucine deprivation are partly FGF21-dependent.
Given the unfeasibility to translate single amino acid deprivation to humans, we focussed on low-protein diets (LPDs) as a more realistic approach.
The LPD increased circulating FGF21 levels with an associated upregulated expression in liver. Analysis of serum human samples from the PREDIMED study extended the correlation between LPD and FGF21 to humans. The ATF4-mediated upregulation of Fgf21 in liver was partially responsible for the weight loss observed in mice fed a LPD, since the liver specific Fgf21 knockout mice (LFgf21KO) mice were partially protected from this loss.
Focusing on the effects of FGF21 on scWAT and given the capacity of FGF21 to produce the browning of white fat depots, we examined the activation of the thermogenic programme in this tissue. Accordingly, scWAT browning caused by the LPD did not occur in mice lacking hepatic Fgf21. As UCP1 activity is related to EE, the blunted induction of Ucp1 in the LPD-fed LFgf21KO mice, may contribute to the reduction in weight loss observed in this mouse model under these circumstances.
The administration of the b-blocker propranolol to protein-restricted mice allowed us to distinguish between the roles of FGF21 and noradrenaline. While Ucp1 expression was upregulated independently of adrenergic signalling, Dio2 and Pparγ expression was blunted by propranolol treatment. These results point to the induction of Ucp1 as a direct effect of liver-delivered FGF21 on scWAT and discard a CNS-mediated effect.
In addition, the LPD improved glucose tolerance, and this improvement was not observed in LFgf21KO mice, indicating a role of FGF21 in glucose metabolism during protein restriction.
Our findings show that the effects of a LPD depend, at least in part, on the circulating levels of FGF21 and consequently on the liver production of this growth factor. Given the parallelism between the results of our study in humans and those in mice, we postulate that modulation of dietary protein content can bring about changes in the circulating levels of FGF21 in mice and humans.L’obesitat i les malalties metabòliques que en deriven són un problema de salut mundial. En aquest context, la recerca d’estratègies terapèutiques pel tractament de l’obesitat ha esdevingut una prioritat. En aquest sentit, el factor metabòlic fibroblast growth factor 21 (FGF21), ha estat identificat com a un prometedor candidat pel tractament de l’obesitat i la síndrome metabòlica. El nostre laboratori va descriure que en resposta a la privació de leucina els nivells de FGF21 augmenten dràsticament i que el factor de transcripció activating transcription factor (ATF4) n’és el responsable. Els resultats d’aquesta tesi són la continuació i desenvolupament d’aquesta observació inicial. Aprofundint en els mecanismes de regulació que controlen l’expressió de FGF21 en resposta a la privació de leucina, els nostres resultats indiquen que el repressor transcripcional Rev-erbα participa significativament en aquesta regulació i que la disminució dels nivells de Rev-erbα correlacionen amb una activació del promotor de FGF21. A més a més, en aquest estudi demostrem que la pèrdua de pes, la disminució de l’expressió de gens lipogènics en fetge i teixit adipós blanc, així com l’activació del teixit adipós marró en resposta a la privació de leucina són, al menys parcialment, dependents de FGF21. Finalment, amb la finalitat de fer els nostres resultats traslladables a humans, demostrem que una dieta amb baix contingut proteic augmenta les nivells circulants de FGF21 en ratolins i humans, i que això succeeix a través de l’increment d’ATF4. L’increment dels nivells de FGF21 degut a la restricció proteica provoquen l’increment de l’expressió dels gens termogènics en el teixit adipós blanc subcutani, la pèrdua de pes i la millora la tolerància a la glucosa. El conjunt d’aquest resultats destaquen el paper clau del factor FGF21 com a mediador dels efectes metabòlics que es produeixen durant la restricció d’aminoàcids i suggereixen la disminució del contingut de proteïna de la dieta com a estratègia per incrementar-ne els nivells.
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Berlo, Carolus Leonardus Hubertus van. "Splanchnic amino acid and ammonia metabolism studies in the pig /." Maastricht : Maastricht : Rijksuniversiteit Maasticht ; University Library, Maastricht University [Host], 1988. http://arno.unimaas.nl/show.cgi?fid=5614.
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Lee, Meng Huee. "Studies on ketoacid-dependent dioxygenases involved in amino acid metabolism." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362049.
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Peiris, Indrani Dammika. "Protein and amino acid metabolism during early pregnancy in sheep." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280540.
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McLean, Mary Anne. "Amino acid neurotransmitter metabolism : computer models and '1'3C-NMR studies." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319780.
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Bruce, Mark. "Amino acid metabolism during exercise and recovery in human subjects." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/33569.
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The depletion of muscle and liver glycogen observed during prolonged submaximal exercise is associated with fatigue. Re-synthesis of glycogen stores during the recovery period after exercise is therefore essential for the recovery of endurance exercise capacity. In recent years, attention has focussed on the supplementation of protein in addition to glucose-polymer during recovery from exercise in an attempt to further increase glycogen synthesis. The aims of the first and second studies in this thesis were to investigate the effect of glucose-polymer and amino acid ingestion, and solely amino acid ingestion upon amino acid and carbohydrate metabolism during recovery from glycogen-depleting exercise.
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Bertolo, Robert Francis. "Amino acid metabolism in parenterally and enterally fed piglets, how important is gut metabolism?" Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0027/NQ51033.pdf.
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Bruce, C. I. "Metabolism of preformed amino acids by rumen bacteria in vivo." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376397.
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Karlsson, Anna. "Exploring amino acid metabolism in Saccharomyces cerevisiae for improved eco-efficient production of chiral amine." Thesis, Malmö universitet, Fakulteten för hälsa och samhälle (HS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-25085.
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Kirala aminer används idag både som aktiva substanser och som bindningsmedel i flertalet läkemedel, dock är dagens produktion med kinetic resolution ineffektiv vilket gör att mer effektiva och miljövänliga produktionssätt eftersträvas. Biotransformation har visat sig både vara miljövänligt och en effektiv metod för att producera kirala aminer. Aminosyror kan användas som aminodonatorer för att producera den kirala aminen 1-methyl-3-phenylpropylamine (MPPA) från prokirala ketonen bensylaceton (BA) med hjälp av aminetransaminas. I denna studie användes metaboliskt konstruerad Saccharomyces cerevisiae med enzymet CV-ωTA för att identifiera vilka aminosyror som var bäst lämpade för MPPA produktion. MPPA produktion kunde detekteras för alla testade aminosyror. Aminosyrans koncentration hade ingen tydlig påverkan på produktionen av MPPA. Alanin vara den aminosyra som gav högst produktionsutbyte följt av lysin. Ingen tydlig relation mellan produktion av MPPA och aminosyrornas koncentrationer kunde ses. Produktionen av MPPA var snabbare än förväntat och var klar redan dag tre för flera av aminosyrorna. Det fanns en antydan att BA kunde vara toxiskt för cellerna i högre koncentrationer och därmed påverka produktionen av MPPA.Chiral amines are used in several types of pharmaceuticals as both active substrates and building blocks, and there is an endeavor to find new and more eco-efficient ways to produce them than today’s production with kinetic resolution. Biotransformation in yeast has shown great potential for production and is also seen as an eco-friendly way to produce chiral amines. Amino acids can be used as an amino donor for the production of chiral amines, e.g. 1-methyl-3-phenylpropylamine (MPPA) from prochiral ketones, e.g. benzylacetone (BA) with aminotransaminase. In this study the production was done with metabolically engineered Saccharomyces cerevisiae, with the gene for the enzyme CV-ωTA transformed. Ten different amino acids were screened in up to three different concentrations for each amino acid. Production of MPPA was observed for all amino acids, with alanine as the most efficient followed by lysine. No clear relationship was seen between amino acid concentration and MPPA production. The production of MPPA for several amino acids were quicker than expected and was completed at day three. Our data indicated a cytotoxic effect of BA at higher concentrations, that negatively affected the production of MPPA.
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Gowrie, Ian Joseph. "A mew method to estimate whole body protein turnover in man." Thesis, City University London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269291.
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Smith, Douglas W. 1961. "The lysinuric protein intolerance phenotype : amino acid transport in cultured skin fibroblasts." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65416.
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Rathbone, Daniel Lee. "Synthetic and enzymatic studies related to branched-chain amino acid metabolism." Thesis, University of Warwick, 1987. http://wrap.warwick.ac.uk/55738/.
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Several sytheses of a-acetolactate analogues (2-hydroxy-3-oxo carboxylic esters) and related compounds were developed. The action of the enzyme acetolactate decarboxylase upon these compounds was studied. A synthesis of 3-bromo-2-oxo carboxylic acids, esters and amides was developed. Inhibition studies using methyl 3-bromo-3-methyl-2-oxo butanoate with pig liver esterase indicated that the esters were not suitable mechanism-based inhibitors of the enzyme. A synthesis of 3-hydroxy-2-oxo carboxylic esters was developed. These compounds were found to isomerise, via alkyl group migration, to the corresponding 2-hydroxy-3-oxo carboxylic esters upon treatment with catalytic quantities of dibutyl tin oxide. Cyclic substrates gave access to 6,7 and 8-membered ring-expanded products. A one-step synthesis of 2-hydroxy-3-oxo carboxylic esters, in high yield, from the corresponding c43-unsaturated esters was developed. This involved the use of acidic manganate (VII) in aqueous acetone and was found to be superior to any synthesis of acyclic 2- hydroxy-3-oxo carboxylic esters published to date. The enzyme acetolactate decarboxylase (ADC) was found to decarboxylate the (S)-isomers of CY-acetolactate and its analogues to give the corresponding (R)-(-hydroxyketones in high optical purity. The (R)-substrates were decarboxylated to (R)-ß. 1'-hydroxyketones via prior isomerisation to (S)-(-acetolactate analogues by a tertiary ketol rearrangement involving carboxylate group migration. As a result (-acetolactate analogues with non-identical substituents at the 2- and 3-positions gave structurally different OF-hydroxyketone products upon decarboxylation with ADC. In the case of C-acetolactate, a substrate with identical substituents at the 2- and 3-positions, both enantiomers were converted into (R)-(-)-acetoin with an enantiomeric excess greater than 98%. This represents an unusual example of the enzymic conversion of both enantiomers of a racemic substrate into a single enantiomer of product. The behaviour of the enzyme towards a range of substrates gave some insight into the nature of the enzyme active site. ADC was found to catalyse, stereospecifically, the incorporation of deuterium into the (R)-isomer of racemic acetoin at the methine position. The chirality of the deuterated and non-deuterated components of the partially deuterated mixture was analysed in situ by vibrational circular dichroism measurements. Acetolactate synthase isozyme II (ALS II) was used to generate QE-acetolactate and its homologues from simple 2-oxo carboxylic acids. These were decarboxylated in situ by ADC to give the corresponding a-hydroxyketones of high optical purity. In one example 01-acetohydroxybutyrate was generated by the action of ALS II upon 2- oxobutanoate. The structure of the single c-hydroxyketone prepared by ADC-catalysed decarboxylation of the 06-acetohydroxybutyrate indicated that the (S)-isomer of Qf-acetohydroxybutyrate had been generated. Model studies were carried out on 2-hydroxycyclohexanone for the stereospecific reduction of the enzymatically produced Ck-hydroxyketones to 1,2-diols. No signifiant chiral induction was observed with sodium borohydride in a range of solvents or with lithium aluminium hydride.
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Barona, Gómez Francisco. "Functional and structural genomics of amino acid metabolism in Streptomyces coelicolor." Thesis, University of Warwick, 2003. http://wrap.warwick.ac.uk/59424/.
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An investigation of amino acid metabolism in Streptomyces coelicolor, including the anabolism of tryptophan, histidine, the branched-chain amino acids and proline, as well as the catabolism of the latter, is reported. The experiments reported herein were conceptually conceived within a functional genomics framework. For this purpose the complete genome sequence of S. coelicolor was systematically exploited. Moreover, the current knowledge on the physiology of Streptomyces was taken onboard, as well as the prevailing and emerging notions on the evolution of proteins and metabolic pathways. Some of the results obtained using S. coelicolor as a model organism were expanded to other actinomycetes, such as Mycobacterium tuberculosis. This was aided by a comparative genomics analysis of the actinomycetes whose genomes have been sequenced. The theoretical principles that give support to this thesis are introduced in Chapter 1. This study was greatly facilitated by the development of a novel PCRtargeting mutagenesis method of which details can be found in Chapter VII. The discovery of a common isomerase for tryptophan and histidine biosynthesis is reported in Chapter II. This discovery arose from efforts aimed at reconstructing the tryptophan biosynthetic pathway of S. coelicolor, since the genome sequence project of this organism failed to identifiy a trpF gene coding for the enzyme phosphoribosyl anthranilate isomerase. The solution of this functional genomics discrepancy led to the discovery of a putative (~a)8-barrel enzyme, termed PriA, whose preliminary functional and structural characterisation is reported in Chapter III. The evolutionary implications of the discovery of PriA are discussed within Chapters III and N. A comparative genomics analysis of actinomycetes centred on the priA gene is presented in the latter Chapter, supporting the notion that this novel protein is spread across the high (0 + C) content Gram-positive organisms. Indeed, it was predicted that a priA orthologue accounts for the lack of a trpF gene from the genome of M tuberculosis, a hypothesis that proved to be correct. Finally, evidence to support the notion that the histidine and tryptophan biosynthetic pathways co-evolved is presented. In contrast to the isomerisation catalysed by PriA, in which an enzyme is shared by two amino acid biosynthetic pathways, several paralogous enzymes with the potential to account for the first step of tryptophan biosynthesis from chorismate were found on the genome of S. coelicolor. These chorismate-utilising enzymes are investigated in Chapter V. Mutational analysis of some of this paralogues is reported and it is anticipated that the analysis and results reported therein will serve to direct future experiments aimed at identifying the trpE paralogue encoding the enzyme anthranilate synthase. Chapter VI reports on the identification of the proC gene involved in the last step of proline biosynthesis in S. coelicolor. The pyrroline-5-carboxylate reductase activity of the enzyme encoded by the putative proC gene was extensively characterised, with particular emphasis on the interaction between primary and secondary metabolism. Furthermore, mutational analysis of proC suggested that paralogues of this gene are present on the genome of this organism, since its deletion did not lead to an auxotrophic phenotype. Investigation of this observation showed that two paralogous enzymes encoded by i1vC-like genes, involved in biosynthesis of the branched-chain amino acids, are capable of compensating for the lack of proC. This is the first example of a physiological link between the biosynthesis of proline and the branched-chain amino acids. To sum up, the results reported in this thesis represent an advancement towards understanding the physiology of S. coelicolor as a model actinomycete, within a functional and structural genomics framework. They also offer evidence on the evolutionary principles that lead to the appearance of novel proteins and metabolic pathways in bacteria.
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Rushowski, Clare Elizabeth. "A study of pathogenicity and amino acid metabolism in Stagonospora nodorum." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390793.
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Heinemann, Björn [Verfasser]. "Amino acid metabolism under drought stress in Arabidopsis thaliana / Björn Heinemann." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://d-nb.info/1238221696/34.
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Howlett, R. M. "Analysis of Campylobacter jejuni amino acid metabolism and solute transport systems." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/3792/.
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Ceppa, Florencia Andrea <1986>. "Diet: Microbiota Interaction in the Gut-Focus on Amino Acid Metabolism." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7348/1/Florencia.Ceppa_tesi.pdf.
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This study aims to measure the impact of protein and amino acid fermentation on the composition and metabolic output of gut microbiota. Although dissimilatory pathways have been described for most amino acids, microbial degradation routes within the gut microbiota are relatively unexplored. The objectives were (1) to characterize amino acid breakdown by the colonic microbiota, (2) to determine the fermentation products formed from individual amino acids/protein (3) to examine how amino acid metabolism is impacted by the presence of a fermentable fiber (prebiotic inulin) and finally (4) to evaluate with an in vivo model (trout fish) diet:microbe interactions and the development of gut microbiota during fish farming. Interactions between the healthy human intestinal microbiota of the distal colon and different combinations of nutrients were simulated using in vitro pH-controlled anaerobic batch cultures of human faeces. Combining high-throughput sequencing of 16S rRNA amplicons, with high-throughput 1H NMR, changes in faecal microbiota composition and metabolic output were measured. During exogenous substrate microbial fermentation (e.g. beef, Trp or fish feed) in the large bowel bioactive compounds (harmful or beneficial) are produced. Many factors affect the gut-microbial metabolism including pH, type and quantity of growth substrate (e.g. protein/carbohydrate) and make up of the gut microbiota. Considerable interindividual variation was observed in response to different digested substrates but over all, the beneficial impact of prebiotic fiber fermentation on production of bioactive compounds from amino acids/proteins was confirmed in this study. In trout, although our dietary intervention with essential oils had little impact on the gut microbiota, the study showed for the first time a dramatic shift in the composition and diversity of the gut microbiota in juvenile, compared to adult fish. Thse observations may have relevance in designing dietary strategies to reduce chronic diseases like colon cancer and heard disease and for fish farming respectively.
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Ceppa, Florencia Andrea <1986>. "Diet: Microbiota Interaction in the Gut-Focus on Amino Acid Metabolism." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7348/.
Full textAbstract:
This study aims to measure the impact of protein and amino acid fermentation on the composition and metabolic output of gut microbiota. Although dissimilatory pathways have been described for most amino acids, microbial degradation routes within the gut microbiota are relatively unexplored. The objectives were (1) to characterize amino acid breakdown by the colonic microbiota, (2) to determine the fermentation products formed from individual amino acids/protein (3) to examine how amino acid metabolism is impacted by the presence of a fermentable fiber (prebiotic inulin) and finally (4) to evaluate with an in vivo model (trout fish) diet:microbe interactions and the development of gut microbiota during fish farming. Interactions between the healthy human intestinal microbiota of the distal colon and different combinations of nutrients were simulated using in vitro pH-controlled anaerobic batch cultures of human faeces. Combining high-throughput sequencing of 16S rRNA amplicons, with high-throughput 1H NMR, changes in faecal microbiota composition and metabolic output were measured. During exogenous substrate microbial fermentation (e.g. beef, Trp or fish feed) in the large bowel bioactive compounds (harmful or beneficial) are produced. Many factors affect the gut-microbial metabolism including pH, type and quantity of growth substrate (e.g. protein/carbohydrate) and make up of the gut microbiota. Considerable interindividual variation was observed in response to different digested substrates but over all, the beneficial impact of prebiotic fiber fermentation on production of bioactive compounds from amino acids/proteins was confirmed in this study. In trout, although our dietary intervention with essential oils had little impact on the gut microbiota, the study showed for the first time a dramatic shift in the composition and diversity of the gut microbiota in juvenile, compared to adult fish. Thse observations may have relevance in designing dietary strategies to reduce chronic diseases like colon cancer and heard disease and for fish farming respectively.
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Miniaci, Sandra A. "Maternal dietary glucose restriction and its effect on amniotic fluid amino acid composition." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ44224.pdf.
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Boyd, Shelton Roosevelt. "Characterization of the amino acid transporter AAP1 in Arabidopsis thaliana." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/99368.
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Amino acids are essential molecules in plant metabolism. Amino acids carry reduced nitrogen while serving as precursors for protein synthesis and secondary metabolites. Translocation of amino acids in the cell is mediated by amino acid transporters. While about 100 transporters have been identified, only a dozen have been fully characterized. The regulation of amino acid transporters is not fully understood and stands as the basis of this study. Previous toxicity-based screenings of Arabidopsis thaliana mutants led to the isolation of a loss-of-function line and the phenylalanine insensitive growth (pig1) mutant capable of growth on toxic concentrations of phenylalanine (1). The pig1-1 mutants also displayed a deregulated metabolism (1). We followed this work with a similar forward genetic screening of Arabidopsis thaliana that led to the identification of 18 mutants capable of growth in the presence of amino acids at toxic concentrations. From this screen, seven mutations were confirmed to affect the amino acid transporter AAP1. Here I demonstrate that, when expressed in yeast deficient for endogenous amino acid transporters, three variant aap1 proteins restored growth similar to yeast complemented by wild type AAP1. Transport of radiolabeled Pro was abolished by variant aap1 proteins while deletion of an intracellular loop spanning the 8th and 9th transmembrane domains reduced Pro transport in yeast. Site directed mutagenesis of this loop conferred a variant aap1 protein which augmented Pro transport in yeast. Amino acid transport in loss-of-function aap1 plants display decreased uptake and increased efflux. In addition, aap1 mutant plants accumulated between 2 and 8 times more free amino acids in the leaves than the wild type. These observations are not fully compatible with the accepted role of AAP1 in transport by the root. The present work describes how the amino acid transporter AAP1 could play a role in regulating amino acid metabolism. We hypothesize that the amino acid transporter AAP1 functions as a senor that is involved in amino acid homeostasis in addition to its established role as a transporter. Is true, this would make AAP1 the first identified amino acid sensor in plants. Knowledge of the mechanism of amino acid sensing would enable us to engineer crops for improved nutrition in a more efficient way than affecting metabolic enzymes.MSLFS
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Cruz, Maria Eliane de Melo da. "The regulation of amino acid and protein metabolism in the lactating rat." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253389.
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AJAZI, ARTA. "ATG6/BECLIN 1 COUPLES THE REPLICATION STRESS RESPONSE TO AMINO ACID METABOLISM." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/471447.
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In the budding yeast Saccharomices Cerevisiae, Atg6 is a non-catalytic component of the phosphatidylinositol (PtdIns) kinase complex Vps34-Vps15-Atg6, which phosphorylates PtdIns to produce phosphatidylinositol 3-phosphate (PtdIns(3)P). Atg6 is conserved among species, including its mammalian ortologue, Beclin 1, which is partially inactivated in breast and ovarian cancers. Beclin 1 involvement in human cancer is not fully established, but it could act as a tumor suppressor by regulating autophagy.
Genome instability is a hallmark of cancer cells. The replication stress checkpoint has evolved to prevent the occurrence of genome instability. Once activated, the checkpoint orchestrates series of protective responses, including the production of deoxyribonucleotides (dNTPs) and DNA repair.
In this work we show that low levels of intracellular PtdIns(3)P, as caused by deletion of ATG6, protect cells during replication stress conditions. Moreover, sensitivity to replication stress is enhanced in the presence of amino acid imbalances in the extracellular medium. This effect depends on PtdIns(3)P involvement in endosomal vesicle trafficking, but is independent from both autophagy and the canonical replication stress checkpoint mediated by Rad53. PtdIns(3)P levels, as determined by the activity of the Vps34-Vps15-Atg6 on endosomal membranes, likely affect the internalization of amino acids that are crucial to survive during replication stress. Elucidating the molecular mechanisms that link the metabolism of specific amino acids with the response to replication stress will have profound impact in understanding the role of Beclin 1 in human cancer and also in cancer therapy.
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Roussel, Guenièvre. "The effects of amino acid deprivation on iron metabolism in Caco-2 cells." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=229800.
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Zhang, Qingfen. "Peptide Fragmentation and Amino Acid Quantification by Mass Spectrometry." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195288.
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Research presented in this dissertation falls into two parts: fragmentation mechanisms of peptide and fragmentation mechanism of amino acid derivatives. The study of peptide fragmentation may help to improve protein identification by incorporating the rules governing this process into search algorithms. This study elucidates the chemical 'rules' governing peptide dissociation. It is believed that these 'rules' can be incorporated into searching algorithms to achieve better protein identification. The present study focuses on the effects of different amino acids on fragmentation. Amino acids with a wide range of different chemical and physical properties are investigated, including amino acids with hydrophilic side chains, amino acids with aliphatic side chains and amino acids without side chains. It can be concluded from the present studies that the different amino acid properties have great influence on the peptide fragmentation and spectrum appearance.The study of fragmentation mechanisms of amino acid derivatives is another focus of this dissertation. Based on the fragmentation mechanism study, a quantification method was developed. The method can distinguish glutamine with 15N-label at N-terminal amine vs the side chain even if they have same molecular weight. Ammonia metabolism was successfully monitored by feeding mosquitoes with isotope-labeled compounds and subsequently measuring the amount of the labeled amino acids. This method demonstrates the power of mass spectrometry in metabolism studies.
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Mueller, Martin J. "Leukotriene A₄ hydrolase : identification of amino acid residues involved in catalyses and substrate-mediated inactivation /." Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4934-4/.
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Zhang, Yongfang. "Amino acid metabolism and requirement in teleost during their early life stages and implications in fish formulated diets." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1199374737.
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Jackson, Nicola Clare. "The effect of nutritional support and GH/IGF-I treatment on glutamine metabolism in the critically ill." Thesis, King's College London (University of London), 2000. https://kclpure.kcl.ac.uk/portal/en/theses/the-effect-of-nutritional-support-and-ghigfi-treatment-on-glutamine-metabolism-in-the-critically-ill(fc28929f-a22e-4dbb-899e-cbb158298674).html.
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Pollard, Matthew. "Cloning and molecular characterisation of novel sodium dependent glutamine and glutamate transport systems." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364871.
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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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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.
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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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Harper, Peter Andrew Windsor. "Studies on neurological disorders of neonatal calves associated with spongy changes in the central nervous system : neuroaxial oedema and the inborn errors of amino acid metabolism." Thesis, The University of Sydney, 1987. https://hdl.handle.net/2123/25996.
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Investigations of neurological disease in neonatal calves were conducted over a four and a half year period.
The studies commenced with so called Hereditary Neuraxial Oedema of Poll Hereford calves. It was determined that two distinct disease entities in this breed had led to confusion regarding the diagnosis of this disorder.
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Yoder, Peter Samuel. "Evaluation of amino acid transport and protein metabolism in the mammary gland of dairy cattle." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/100897.
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Improving our understanding of milk protein production regulation and AA transport is important for successfully formulating diets for AA and improving N efficiency. The objectives were to study protein synthesis regulation and AA transport using in vitro and in vivo models. In the first experiment, the objective was to evaluate the ability of five distinct AA profiles and balancing Lys to Met ratio to 3:1 to stimulate protein translation. No single AA profile uniquely stimulated phosphorylation of translational machinery related proteins suggesting identification of a single optimal AA profile as unlikely. In the second experiment, an in vitro method using three different AA isotopes was developed to trace AA movement. The method assesses bi-directional transport of multiple AA simultaneously enabling evaluation of unidirectional uptake kinetics. This method was used to evaluate AA concentrations representing 16, 100, 186, and 271% of cow plasma AA concentrations. Amino acid uptake was not saturable within the in vivo range for eleven AA. Arginine, Val, and Pro exhibited saturation with the Michaelis-Menten km being 95, 49, and 65% of in vivo concentrations. Results suggest that AA transport is generally non-saturable and that high bi-directional transport exists which enables a mechanism for mitigating AA shortages. In experiment 3, the objective was to evaluate milk protein production and regulation from infusing Met, Lys, and His (MKH) or Ile and Leu (IL). The two EAA groups independently and additively increased milk protein yield. This finding contradicts the single limiting AA theory that a single nutrient will limit milk protein yield. Changes in udder AA extraction and blood flow from supplemental EAA reveal flexible delivery mechanisms. The phosphorylation state of proteins associated with the mTOR pathway was impacted by both EAA treatments. Changes in the udder proteome suggest negative feedback on mTOR pathway activation when milk protein yield was increased by the EAA groups separately but when supplemented together, negative feedback was lessened. Results indicate that multiple EAA can stimulate milk protein production, the ability of AA transport to match intracellular needs, and that the single limiting AA theory or existence of a unique optimal AA profile is likely irrelevant in dairy cows.Doctor of Philosophy