Relevant bibliographies by topics / Amino acid metabolism

Academic literature on the topic 'Amino acid metabolism'

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Published: 4 June 2021
Last updated: 14 March 2023

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Journal articles on the topic "Amino acid metabolism"

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Chandel, Navdeep S. "Amino Acid Metabolism." Cold Spring Harbor Perspectives in Biology 13, no. 4 (April 2021): a040584. http://dx.doi.org/10.1101/cshperspect.a040584.

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KNOWLES, R. G. "Amino Acid Metabolism." Biochemical Society Transactions 14, no. 5 (October 1, 1986): 988–89. http://dx.doi.org/10.1042/bst0140988b.

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Broquist, Harry P. "Amino Acid Metabolism." Nutrition Reviews 34, no. 10 (April 27, 2009): 289–93. http://dx.doi.org/10.1111/j.1753-4887.1976.tb05672.x.

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Lee, Jeremy S. "Amino acid metabolism." Biochemical Education 14, no. 3 (July 1986): 148. http://dx.doi.org/10.1016/0307-4412(86)90187-1.

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Kasperek, George J. "Amino acid metabolism." National Strength & Conditioning Association Journal 10, no. 6 (1988): 23. http://dx.doi.org/10.1519/0744-0049(1988)010<0023:aam>2.3.co;2.

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Reggiani, R., and A. Bertani. "Anaerobic Amino Acid Metabolism." Russian Journal of Plant Physiology 50, no. 6 (November 2003): 733–36. http://dx.doi.org/10.1023/b:rupp.0000003270.33010.22.

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Hjelm, M., and J. Seakins. "Modelling amino acid metabolism." Amino Acids 3, no. 1 (1992): 1–23. http://dx.doi.org/10.1007/bf00806006.

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Muhammad, Nefertiti, Hyun Min Lee, and Jiyeon Kim. "Oncology Therapeutics Targeting the Metabolism of Amino Acids." Cells 9, no. 8 (August 15, 2020): 1904. http://dx.doi.org/10.3390/cells9081904.

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Amino acid metabolism promotes cancer cell proliferation and survival by supporting building block synthesis, producing reducing agents to mitigate oxidative stress, and generating immunosuppressive metabolites for immune evasion. Malignant cells rewire amino acid metabolism to maximize their access to nutrients. Amino acid transporter expression is upregulated to acquire amino acids from the extracellular environment. Under nutrient depleted conditions, macropinocytosis can be activated where proteins from the extracellular environment are engulfed and degraded into the constituent amino acids. The demand for non-essential amino acids (NEAAs) can be met through de novo synthesis pathways. Cancer cells can alter various signaling pathways to boost amino acid usage for the generation of nucleotides, reactive oxygen species (ROS) scavenging molecules, and oncometabolites. The importance of amino acid metabolism in cancer proliferation makes it a potential target for therapeutic intervention, including via small molecules and antibodies. In this review, we will delineate the targets related to amino acid metabolism and promising therapeutic approaches.
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S, Anwar. "Analysis of Arabidopsis amino acid metabolism in response to Heterodera schachtii infection." Pakistan Journal of Nematology 36, no. 2 (July 1, 2018): 131–50. http://dx.doi.org/10.18681/pjn.v36.i02.p131-150.

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Puran, M., L. Dorland, J. B. C. de Klerk, F. J. Van Sprang, and S. K. Wadman. "Disorders of Amino Acid Metabolism." Scandinavian Journal of Clinical and Laboratory Investigation 48 (1988): 75–77. http://dx.doi.org/10.3109/00365518809168514.

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Dissertations / Theses on the topic "Amino acid metabolism"

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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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Books on the topic "Amino acid metabolism"

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Amino acid metabolism. 2nd ed. Chichester: Wiley, 1985.

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Bender, David A. Amino Acid Metabolism. Chichester, UK: John Wiley & Sons, Ltd, 2012. http://dx.doi.org/10.1002/9781118357514.

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Bender, David A. Amino acid metabolism. 3rd ed. Chichester, West Sussex: John Wiley & Sons, 2012.

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A, Cynober Luc, ed. Amino acid metabolism and therapy in health and nutritional disease. Boca Raton: CRC Press, 1995.

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Pisters, Peter W. T., and Murray F. Brennan. Protein and Amino Acid Metabolism in Cancer Cachexia. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-662-22346-8.

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T, Pisters Peter W., and Brennan Murray F, eds. Protein and amino acid metabolism in cancer cachexia. New York: Springer, 1996.

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Pisters, Peter W. T., 1960- and Brennan Murray F, eds. Protein and amino acid metabolism in cancer cachexia. New York: Chapman & Hall, 1996.

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Lee, Edward Robert. Investigations related to branched-chain amino acid metabolism. [s.l.]: typescript, 1989.

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Mazoyer, B. M., W. D. Heiss, and D. Comar, eds. PET Studies on Amino Acid Metabolism and Protein Synthesis. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1620-6.

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E, El-Khoury Antoine, ed. Methods for investigation of amino acid and protein metabolism. Boca Raton, FL: CRC Press, 1999.

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Book chapters on the topic "Amino acid metabolism"

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Chandler, A. M. "Amino Acid Metabolism." In Oklahoma Notes, 80–103. New York, NY: Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4612-4200-0_5.

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Fromm, Herbert J., and Mark S. Hargrove. "Amino Acid Metabolism." In Essentials of Biochemistry, 279–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-19624-9_13.

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Chandler, A. M. "Amino Acid Metabolism." In Oklahoma Notes, 77–99. New York, NY: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-0294-0_5.

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Chandler, A. M. "Amino Acid Metabolism." In Oklahoma Notes, 78–99. New York, NY: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4684-0437-1_5.

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Rogosa, Morrison, Micah I. Krichevsky, and Rita R. Colwell. "Amino Acid Metabolism." In Springer Series in Microbiology, 182–86. New York, NY: Springer New York, 1986. http://dx.doi.org/10.1007/978-1-4612-4986-3_31.

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Morot-Gaudry, Jean-François, Dominique Job, and Peter J. Lea. "Amino Acid Metabolism." In Plant Nitrogen, 167–211. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-662-04064-5_7.

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Wu, Guoyao. "Regulation of Amino Acid Metabolism." In Amino Acids, 499–535. 2nd ed. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003092742-10.

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Wu, Guoyao. "Inborn Errors of Amino Acid Metabolism." In Amino Acids, 623–70. 2nd ed. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003092742-12.

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Li, Ting, Christopher Copeland, and Anne Le. "Glutamine Metabolism in Cancer." In The Heterogeneity of Cancer Metabolism, 17–38. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65768-0_2.

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AbstractMetabolism is a fundamental process for all cellular functions. For decades, there has been growing evidence of a relationship between metabolism and malignant cell proliferation. Unlike normal differentiated cells, cancer cells have reprogrammed metabolism in order to fulfill their energy requirements. These cells display crucial modifications in many metabolic pathways, such as glycolysis and glutaminolysis, which include the tricarboxylic acid (TCA) cycle, the electron transport chain (ETC), and the pentose phosphate pathway (PPP) [1]. Since the discovery of the Warburg effect, it has been shown that the metabolism of cancer cells plays a critical role in cancer survival and growth. More recent research suggests that the involvement of glutamine in cancer metabolism is more significant than previously thought. Glutamine, a nonessential amino acid with both amine and amide functional groups, is the most abundant amino acid circulating in the bloodstream [2]. This chapter discusses the characteristic features of glutamine metabolism in cancers and the therapeutic options to target glutamine metabolism for cancer treatment.
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Takagi, Hiroshi, and Iwao Ohtsu. "l-Cysteine Metabolism and Fermentation in Microorganisms." In Amino Acid Fermentation, 129–51. Tokyo: Springer Japan, 2016. http://dx.doi.org/10.1007/10_2016_29.

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Conference papers on the topic "Amino acid metabolism"

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Lin, Gigin, Helen Troy, Gabriela Andrejeva, Anne-Christine LF Wong Te Fong, Dow-Mu Koh, Simon P. Robinson, Ian R. Judson, John R. Griffiths, Martin O. Leach, and Yuen-Li Chung. "Abstract B56: Treatment-induced autophagy increases amino acid uptake and switches glucose addiction to amino acid catabolism in cancer." In Abstracts: AACR Special Conference: Metabolism and Cancer; June 7-10, 2015; Bellevue, WA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1557-3125.metca15-b56.

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ISMAILOV, Ismail Sagidovich, Nina Vladimirovna TREGUBOVA, Rashid Hasanbievich KOCHKAROV, Anna Victorovna MORGUNOVA, and Natalija Alecseevna DRIZHD. "THE RELATIONSHEEP OF AMINO ACID METABOLISM WITH PRODUCTIVITY OF GROWING YOUNG SHEEP." In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.125.

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A number of studies on digestion of the ruminants have shown the process of synthesis of all the essential amino acids in the rumen (Abu Fadel, 2004; Trukhachev, V., Zlidnev, N. 2008). However, according to some researches, microbial protein is deficient in methionine and lysine. This assumption also proves the need for further study of the influence of balanced amino acids to these diets on the growth, development and productive performance of the ruminants. Scientific approbation of the issues related to establishing the requirements of young sheep in lysine and methionine with cystine and development of recommendations for their proper balance in animal rations have been conducted along with a series of physiological, scientific and practical experiments. For this purpose, we used the following research methods: preparative, analytical, measuring and calculating. Zootechnical evaluation of young sheep’s diet with different levels of lysine and methionine with cysteine has been conducted, and influence of these components on growth, development, metabolism, the use of amino acids and wool productivity have been studied. The importance of studying the content of amino acids in plasma is evident because they are the indicators of protein metabolism in the animals’ organism and represent themselves the exchange fund when used in the biochemical transformations in the process of updating the protein of the body tissues and the synthesis of animal products. Increase in young sheep’s diet of lysine and methionine can improve their productivity, reduce the cost of feed energy and improve biochemical indexes of meat, taking into account the optimization of its amino acid composition. Efficiency increase of young sheep during the process of the individual development is linked to conditions of feeding and in particular the usefulness of a protein food, which is primarily determined by sufficient intake of essential amino acids - lysine and methionine with cystine. Thus, the inclusion in the diet of growing young sheep some amount of synthetic amino acids – 6–8 grams of lysine and 3–4 g of methionine per 1 fodder unit, enhances oxidation-reduction processes, increase productivity, i.e. wool yield and other indicators. The content of free amino acids in plasma directly depends on their availability in feed. The use of synthetic amino acids (lysine, methionine and cystine) contributed to the increase of their content in a free state in the blood serum, indicating their increased demand in sheep. With the use of different doses of synthetic amino acids (lysine, methionine, cystine) in the diets of young sheep it has been found that the organization of optimum conditions of feeding, care and management of sheep in winter season help to avoid abrupt changes in the structure of the skin, to ensure the normal development of the histological structure and morphogenetic processes.)
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Gwinn, Dana, and Alejandro Sweet-Cordero. "Abstract 30: Kras mediates amino acid metabolism during nutrient stress." In Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.am2016-30.

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Florescu, I. C., U. Krogh, and J. V. Nørgaard. "Amino acid absorption kinetics in pigs fed different protein sources." In 6th EAAP International Symposium on Energy and Protein Metabolism and Nutrition. The Netherlands: Wageningen Academic Publishers, 2019. http://dx.doi.org/10.3920/978-90-8686-891-9_86.

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Erez, Ayelet, and Eytan Ruppin. "Abstract IA02: Regulating amino acid metabolism can improve response to immunotherapy." In Abstracts: AACR Special Virtual Conference on Epigenetics and Metabolism; October 15-16, 2020. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1538-7445.epimetab20-ia02.

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Breault, Daniel, Divya Bappanad, Svati Shah, Damian Craig, Carol Haynes, William Kraus, Charles Cairns, et al. "Altered Branch Chain Amino Acid Metabolism In Chronic Obstructive Pulmonary Disease." In American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California. American Thoracic Society, 2012. http://dx.doi.org/10.1164/ajrccm-conference.2012.185.1_meetingabstracts.a6836.

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Weil, J., A. Beitia, N. Suesuttajit, K. Hilton, P. Maharjan, J. Caldas, S. Rao, and C. N. Coon. "Determining amino acid requirements for broiler breeders using the nitrogen balance method." In 6th EAAP International Symposium on Energy and Protein Metabolism and Nutrition. The Netherlands: Wageningen Academic Publishers, 2019. http://dx.doi.org/10.3920/978-90-8686-891-9_149.

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Fernandez-Zapico, Martin, Dae Won Kim, Philip Philip, Alexander Vandell, Jonathan Eckard, Ron Korn, Giuseppe Del Priore, and Diane Simeone. "Abstract B15: Therapeutic potential of targeting amino acid metabolism in pancreatic cancer." In Abstracts: AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; September 6-9, 2019; Boston, MA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1538-7445.panca19-b15.

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Binggeli, S., H. Lapierre, E. Charbonneau, D. R. Ouellet, and D. Pellerin. "Alteration of feeding and cropping strategies by amino acid recommendations on Canadian dairy farms." In 6th EAAP International Symposium on Energy and Protein Metabolism and Nutrition. The Netherlands: Wageningen Academic Publishers, 2019. http://dx.doi.org/10.3920/978-90-8686-891-9_161.

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Berezovscaia, Elena, Lulia Lupasco, Svetlana Garaeva, and Galina Postolati. "PARTICULARITIES OF AMINO ACID METABOLISM IN PATIENTS WITH CHRONIC VIRAL HEPATITIS HBV ETIOLOGY." In XV International interdisciplinary congress "Neuroscience for Medicine and Psychology". LLC MAKS Press, 2019. http://dx.doi.org/10.29003/m325.sudak.ns2019-15/92.

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Reports on the topic "Amino acid metabolism"

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Spielman, Daniel. In Vivo Imaging of Branched Chain Amino Acid Metabolism in Prostate Cancer. Fort Belvoir, VA: Defense Technical Information Center, August 2012. http://dx.doi.org/10.21236/ada581343.

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Spielman, Daniel. In Vivo Imaging of Branched Chain Amino Acid Metabolism in Prostate Cancer. Fort Belvoir, VA: Defense Technical Information Center, August 2013. http://dx.doi.org/10.21236/ada590428.

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Varga, Gabriella A., Amichai Arieli, Lawrence D. Muller, Haim Tagari, Israel Bruckental, and Yair Aharoni. Effect of Rumen Available Protein, Amimo Acids and Carbohydrates on Microbial Protein Synthesis, Amino Acid Flow and Performance of High Yielding Cows. United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568103.bard.

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The effect of rumen available protein amino acids and carbohydrates on microbial protein synthesis, amino acid flow and performance of high yielding dairy cows was studied. A significant relationship between the effective degradabilities of OM in feedstuffs and the in vivo ruminal OM degradation of diets of dairy cows was found. The in situ method enabled the prediction of ruminal nutrients degradability response to processing of energy and nitragenous supplements. The AA profile of the rumen undegradable protein was modified by the processing method. In a continuous culture study total N and postruminal AA flows, and bacterial efficiency, is maximal at rumen degradable levels of 65% of the CP. Responses to rumen degradable non carbohydrate (NSC) were linear up to at least 27% of DM. Higher CP flow in the abomasum was found for cows fed high ruminally degradable OM and low ruminally degradable CP diet. It appeared that in dairy cows diets, the ratio of rumen degradable OM to rumenally degradable CP should be at least 5:1 in order to maximize postruminal CP flow. The efficiency of microbial CP synthesis was higher for diets supplemented with 33% of rumen undegradable protein, with greater amounts of bacterial AA reaching the abomasum. Increase in ruminal carbohydrate availability by using high moisture corn increased proportions of propionate, postruminal nutrients flow, postruminal starch digestibility, ruminal availability of NSC, uptake of energy substrates by the mammory gland. These modifications resulted with improvement in the utilization of nonessential AA for milk protein synthesis, in higher milk protein yield. Higher postruminal NSC digestibility and higher efficiency of milk protein production were recorded in cows fed extruded corn. Increasing feeding frequency increased flow of N from the rumen to the blood, reduced diurnal variation in ruminal and ammonia, and of plasma urea and improved postruminal NSC and CIP digestibility and total tract digestibilities. Milk and constituent yield increased with more frequent feeding. In a study performed in a commercial dairy herd, changes in energy and nitrogenous substrates level suggested that increasing feeding frequency may improve dietary nitrogen utilization and may shift metabolism toward more glucogenesis. It was concluded that efficiency of milk protein yield in high producing cows might be improved by an optimization of ruminal and post-ruminal supplies of energy and nitrogenous substrates. Such an optimization can be achieved by processing of energy and nitrogenous feedstuffs, and by increasing feeding frequency. In situ data may provide means for elucidation of the optimal processing conditions.
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Anderson, Olin D., Gad Galili, and Ann E. Blechl. Enhancement of Essential Amino Acids in Cereal Seeds: Four Approaches to Increased Lysine Content. United States Department of Agriculture, October 1998. http://dx.doi.org/10.32747/1998.7585192.bard.

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Cereal seeds are the basis of the human diet, and their amino acid composition is thus of major nutritional and economic importance. Currently, deficiencies in essential amino acids are addressed, when possible, by additionalprotein sources or by supplementing animal feed with non-cereal protein or synthetic amino acids. A number of strategies have been suggested to make cereal flours more complete and balanced sources of amino acids, although systematic examination of such strategies is rare. This project proposed to begin such a systematic examination using four complementary and parallel approaches to increasing wheat seed lysine: 1) Modifying endogenous wheat seed proteins for increased lysine composition. 2) Overexpression of naturally occurring high-lysine proteins in the wheat endosperm. 3) Ectopic expression of proteins in the wheat endosperm. 4) Alteration of free lysine levels in the wheat endosperm. The results of these studies are expected to be wheat lines with increased lysine content and will establish a clearer understanding of the approaches most likely to enhance cereal seed protein quality. Progress is reported for all four objectives, with a significant foundation for further work on two of the objectives (modification of wheat storage proteins and lysine metabolism). Plans for continuing work on all four objectives are briefly outlined.
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Blumwald, Eduardo, and Avi Sadka. Sugar and Acid Homeostasis in Citrus Fruit. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7697109.bard.

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Citrus fruit quality standards have been determined empirically, depending on species and on the particular growing regions. In general, the TSS (total soluble solids) to total acidity (TA) ratio determines whether citrus fruit can be marketed. Soluble sugars account for most of the TSS during harvest while TA is determined almost solely by the citric acid content, which reaches levels of 1-5% by weight in many cultivated varieties. Acid and sugar homeostasis in the fruit is critical for the management of existing cultivars, the development of new cultivars, the improvement of pre- and post-harvest strategies and the control of fruit quality and disorders. The current proposal (a continuation of a previous proposal) aimed at: (1) completing the citrus fruit proteome and metabolome, and establish a citrus fruit functional database, (2) further characterization of the control of fruit acidity by studying the regulation of key steps affecting citrate metabolism, and determine the fate of citrate during acid decline stage, and (3) Studying acid and sugar homeostasis in citrus fruits by characterizing transport mechanisms across membranes. These aims were completed as the following: (1) Our initial efforts were aimed at the characterization and identification of citric acid transporters in citrus juice cells. The identification of citrate transporters at the vacuole of the citrus juice cell indicated that the steady-state citrate cytosolic concentration and the action of the cytosolic aconitase were key elements in establishing the pH homeostat in the cell that regulates the metabolic shift towards carbon usage in the fruit during the later stages of fruit development. We focused on the action of aconitase, the enzyme mediating the metabolic use of citric acid in the cells, and identified processes that control carbon fluxes in developing citrus fruits that control the fruit acid load; (2) The regulation of aconitase, catalyzing a key step in citrate metabolism, was further characterized by using two inhibitors, citramalte and oxalomalte. These compounds significantly increased citrate content and reduced the enzyme’s activity. Metabolite profiling and changes of amino-acid metabolizing enzymes in oxalomalate- treated cells suggested that the increase in citrate, caused by aconitase inhibition, induces amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in citrus fruit. (3) We have placed a considerable amount of time on the development of a citrus fruit proteome that will serve to identify all of the proteins in the juice cells and will also serve as an aid to the genomics efforts of the citrus research community (validating the annotation of the fruit genes and the different ESTs). Initially, we identified more than 2,500 specific fruit proteins and were able to assign a function to more than 2,100 proteins (Katz et al., 2007). We have now developed a novel Differential Quantitative LC-MS/MS Proteomics Methodology for the identification and quantitation of key biochemical pathways in fruits (Katz et al., 2010) and applied this methodology to identify determinants of key traits for fruit quality (Katz et al., 2011). We built “biosynthesis maps” that will aid in defining key pathways associated with the development of key fruit quality traits. In addition, we constructed iCitrus (http://wiki.bioinformatics.ucdavis.edu/index.php/ICitrus), a “functional database” that is essentially a web interface to a look-up table that allows users to use functional annotations in the web to identify poorly annotated citrus proteins. This resource will serve as a tool for growers and field extension specialists.
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Galili, Gad, Harry J. Klee, and Asaph Aharoni. Elucidating the impact of enhanced conversion of primary to secondary metabolism on phenylpropanoids secondary metabolites associated with flavor, aroma and health in tomato fruits. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597920.bard.

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• Targeted manipulating Phenylalanine (Phe) synthesis is one of the most powerful strategies to boost the biologically and economically important secondary metabolites, including phenylpropaniods, aromatic volatiles and specialized secondary metabolites. • Over-expression of the petunia MYB transcript factor, ODORANT1 (ODO1), results in significant alterations of the levels of specific phenylpropanoid compounds in plants. • Our previous studies indicated that ectopic expression of the feedback-insensitive AroG could break the bottleneck between primary and secondary metabolisms in tomato, thereby aiding in producing new tomato composition and identifying the unknown roles of multiple key regulators in specialized metabolism. Therefore, combining the AroG and ODO1 is of particular interest for elucidating the combined regulatory role of both of these genes in the Phe metabolic pathway, as well as generating tomato fruits that contain higher levels of secondary metabolites. • Here, we performed the LC-MS and GC-MS analyses on fruits of four tomato genotypes, namely, wild type tomato fruits as well as tomato fruits expressing the AroG, ODO1 and the combination of AroG plus ODO1 (AO) genotypes. Our results elaborated that the levels of many of the Phe-derived metabolites were predominately altered in fruits of the AO genotype, compared to tomato fruits expressing either AroG or ODO1 individually. The levels of most of these metabolites were significantly stimulated, such as Tyrosine (Tyr), coumaric acid and ferulic acid derived metabolites, but the levels of some important secondary metabolites were reduced in the AO transgenic genotypes as compared to either AroG or ODO1 lines. Nevertheless, our results also revealed that the levels of aromatic volatiles were obviously down regulated in the AO, compared to that in AroG transgenic fruits, but were boosted while compared to the wild type and ODO1 transgenic fruits. • Our results suggest that ODO1 expression may also have a negative effect on the production of some of the aromatic volatiles in tomato fruits, indicating that ODO1 acts as an important regulator of the shikimate pathway, which leads to the production of the aromatic amino acids and secondary metabolites derived from them. Key words: AroG, ODO1, tomato, metabolism, shikimate pathway
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Jander, Georg, Gad Galili, and Yair Shachar-Hill. Genetic, Genomic and Biochemical Analysis of Arabidopsis Threonine Aldolase and Associated Molecular and Metabolic Networks. United States Department of Agriculture, January 2010. http://dx.doi.org/10.32747/2010.7696546.bard.

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Since the amino acids threonine and isoleucine can be limiting in mammalian diet and there is interest in increasing their abundance in certain crop plants. To meet this need, a BARD proposal was written with two main research objectives: (i) investigate new avenues for manipulating threonine and isoleucine content in plants and (ii) study the role of threonine aldolase in plant metabolism. Research conducted to meet these goals included analysis of the sub-cellular localization of threonine aldolase in the plant, analysis of metabolic flux in developing embryos, over- and under-expression of Arabidopsis threonine aldolases, and transcriptional and metabolic analysis of perturbations resulting from altered threonine aldolase expression. Additionally, the broader metabolic effects of increasing lysine biosynthesis were investigated. An interesting observation that came up in the course of the project is that threonine aldolase activity affects methionine gamma-lyase in Arabidopsis. Further research showed that threonine deaminase and methionine gamma-lyase both contribute to isoleucine biosynthesis in plants. Therefore, isoleucine content can be altered by manipulating the expression of either or both of these enzymes. Additionally, both enzymes contribute to the up to 100-fold increase in isoleucine that is observed in drought-stressed Arabidopsis. Toward the end of the project it was discovered that through different projects, both groups had been able to independently up-regulate phenylalanine accumulation by different mechanisms. The Galili lab transformed Arabidopsis with a feedbackinsensitive bacterial enzyme and the Jander lab found a feedback insensitive mutation in Arabidopsis arogenate dehydratase. Exchange of the respective plant lines has allowed a comparative analysis of the different methods for increasing phenylalanine content and the creation of double mutants. The research that was conducted as part of this BARD project has led to new insights into plant amino acid metabolism. Additionally, new approaches that were found to increase the accumulation of threonine, isoleucine, and phenylalanine in plants have potential practical applications. Increased threonine and isoleucine levels can increase the nutritional value of crop plants. Elevated isoleucine accumulation may increase the osmotic stress tolerance of plants. Up-regulation of phenylalanine biosynthesis can be used to increase the production of downstream higher-value plant metabolites of biofuel feed stocks.
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Whitham, Steven A., Amit Gal-On, and Tzahi Arazi. Functional analysis of virus and host components that mediate potyvirus-induced diseases. United States Department of Agriculture, March 2008. http://dx.doi.org/10.32747/2008.7591732.bard.

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The mechanisms underlying the development of symptoms in response to virus infection remain to be discovered in plants. Insight into symptoms induced by potyviruses comes from evidence implicating the potyviral HC-Pro protein in symptom development. In particular, recent studies link the development of symptoms in infected plants to HC-Pro's ability to interfere with small RNA metabolism and function in plant hosts. Moreover, mutation of the highly conserved FRNK amino acid motif to FINK in the HC-Pro of Zucchini yellow mosaic virus (ZYMV) converts a severe strain into an asymptomatic strain, but does not affect virus accumulation in cucurbit hosts. The ability of this FINK mutation to uncouple symptoms from virus accumulation creates a unique opportunity to study symptom etiology, which is usually confounded by simultaneous attenuation of both symptoms and virus accumulation. Our goal was to determine how mutations in the conserved FRNK motif affect host responses to potyvirus infection in cucurbits and Arabidopsis thaliana. Our first objective was to define those amino acids in the FRNK motif that are required for symptoms by mutating the FRNK motif in ZYMV and Turnip mosaic virus (TuMV). Symptom expression and accumulation of resulting mutant viruses in cucurbits and Arabidopsis was determined. Our second objective was to identify plant genes associated with virus disease symptoms by profiling gene expression in cucurbits and Arabidopsis in response to mutant and wild type ZYMV and TuMV, respectively. Genes from the two host species that are differentially expressed led us to focus on a subset of genes that are expected to be involved in symptom expression. Our third objective was to determine the functions of small RNA species in response to mutant and wild type HC-Pro protein expression by monitoring the accumulation of small RNAs and their targets in Arabidopsis and cucurbit plants infected with wild type and mutant TuMV and ZYMV, respectively. We have found that the maintenance of the charge of the amino acids in the FRNK motif of HC-Pro is required for symptom expression. Reduced charge (FRNA, FRNL) lessen virus symptoms, and maintain the suppression of RNA silencing. The FRNK motif is involved in binding of small RNA species including microRNAs (miRNA) and short interfering RNAs (siRNA). This binding activity mediated by the FRNK motif has a role in protecting the viral genome from degradation by the host RNA silencing system. However, it also provides a mechanism by which the FRNK motif participates in inducing the symptoms of viral infection. Small RNA species, such as miRNA and siRNA, can regulate the functions of plant genes that affect plant growth and development. Thus, this binding activity suggests a mechanism by which ZYMVHC-Pro can interfere with plant development resulting in disease symptoms. Because the host genes regulated by small RNAs are known, we have identified candidate host genes that are expected to play a role in symptoms when their regulation is disrupted during viral infections. As a result of this work, we have a better understanding of the FRNK amino acid motif of HC-Pro and its contribution to the functions of HC-Pro, and we have identified plant genes that potentially contribute to symptoms of virus infected plants when their expression becomes misregulated during potyviral infections. The results set the stage to establish the roles of specific host genes in viral pathogenicity. The potential benefits include the development of novel strategies for controlling diseases caused by viruses, methods to ensure stable expression of transgenes in genetically improved crops, and improved potyvirus vectors for expression of proteins or peptides in plants.
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Ginzberg, Idit, Richard E. Veilleux, and James G. Tokuhisa. Identification and Allelic Variation of Genes Involved in the Potato Glycoalkaloid Biosynthetic Pathway. United States Department of Agriculture, August 2012. http://dx.doi.org/10.32747/2012.7593386.bard.

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Steroidal glycoalkaloids (SGAs) are secondary metabolites being part of the plant defense response. The two major SGAs in cultivated potato (Solanum tuberosum) are α-chaconine and α-solanine, which exhibit strong cellular lytic properties and inhibit acetylcholinesterase activity, and are poisonous at high concentrations for humans. As SGAs are not destroyed during cooking and frying commercial cultivars have been bred to contain low levels, and their content in tubers should not exceed 20 mg/100 g fresh weight. However, environmental factors can increase tuber SGA content above the safe level. The focus of the proposed research was to apply genomic approaches to identify candidate genes that control potato SGA content in order to develop tools for potato improvement by marker-assisted selection and/or transgenic approaches. To this end, the objectives of the proposal included identification of genes, metabolic intermediates and allelic variations in the potato SGAbiosynthetic pathway. The SGAs are biosynthesized by the sterol branch of the mevalonic acid/isoprenoid pathway. Transgenic potato plants that overexpress 3-hydroxy-3-methylglutaryl-CoA reductase 1 (HMG1) or squalene synthase 1 (SQS1), key enzymes of the mevalonic acid/isoprenoid pathway, exhibited elevated levels of solanine and chaconine as well as induced expression of genes downstream the pathway. These results suggest of coordinated regulation of isoprenoid (primary) metabolism and SGA secondary metabolism. The transgenic plants were further used to identify new SGA-related candidate genes by cDNA-AFLP approach and a novel glycosyltransferase was isolated. In addition, genes involved in phytosterol biosynthesis may have dual role and synthesize defense-related steroidal metabolites, such as SGAs, via lanosterol pathway. Potato lanosterol synthase sequence (LAS) was isolated and used to prepare transgenic plants with overexpressing and silencing constructs. Plants are currently being analyzed for SGA content. The dynamics of SGA accumulation in the various organs of a potato species with high SGA content gave insights into the general regulation of SGA abundance. Leaf SGA levels in S. chacoense were 10 to 20-fold greater than those of S. tuberosum. The leptines, SGAs with strong antifeedant properties against Colorado potato beetles, were present in all aerial tissues except for early and mid-developmental stages of above ground stolons, and accounted for the high SGA content of S. chacoense. These results indicate the presence of regulatory mechanisms in most tissues except in stolons that limit the levels of α-solanine and α-chaconine and confine leptine accumulation to the aerial tissues. The genomes of cultivated and wild potato contain a 4-member gene family coding for SQS. Three orthologs were cloned as cDNAs from S. chacoense and heterologously expressed in E. coli. Squalene accumulated in all E. coli lines transformed with each of the three gene constructs. Differential transcript abundance in various organs and amino acid sequence differences in the conserved domains of three isoenzymes indicate subfunctionalization of SQS activity and triterpene/sterol metabolism. Because S. chacoense and S. phureja differ so greatly for presence and accumulation of SGAs, we selected four candidate genes from different points along the biosynthetic pathway to determine if chcor phuspecific alleles were associated with SGA expression in a segregating interspecific diploid population. For two of the four genes (HMG2 and SGT2) F2 plants with chcalleles expressed significantly greater total SGAs compared with heterozygotes and those with phualleles. Although there are other determinants of SGA biosynthesis and composition in potato, the ability of allelic states at two genes to affect SGA levels confirms some of the above transgenic work where chcalleles at two other loci altered SGA expression in Desiree. Present results reveal new opportunities to manipulate triterpene/sterol biosynthesis in more targeted ways with the objective of altering SGA content for both human health concerns and natural pesticide content without disrupting the essential metabolism and function of the phytosterol component of the membranes and the growth regulating brassinosteroids.
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Dudareva, Natalia, Alexander Vainstein, Eran Pichersky, and David Weiss. Integrating biochemical and genomic approaches to elucidate C6-C2 volatile production: improvement of floral scent and fruit aroma. United States Department of Agriculture, September 2007. http://dx.doi.org/10.32747/2007.7696514.bard.

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The specific objectives of approved proposal include to: 1. Elucidate the C6-C2 biochemical pathways leading to the biosynthesis of phenylacetaldehyde, phenylethyl alcohol and phenylethyl acetate in floral tissues of ornamentally important plants, pefunia and roses. 2. Isolate and characterrze genes responsible for the production of these C6-C2 compounds and those involved in the regulation of the pathway using genomic and transcriptomic tools. 3. Determine whether altering the expression of key genes of this pathway can result in changing the aroma characteristics of flowers. Aldehydes are intermediates in a variety of biochemical pathways including those involved in the metabolism of carbohydrates, vitamins, steroids, amino acids, benzylisoquinoline alkaloids, hormones, and lipids. In plants they are also synthesized in response to environmental stresses such as salinity, cold, and heat shock or as flavors and aromas in fruits and flowers. Phenylacetaldehyde along with 2-phenylethanol and its acetate ester, are important scent compounds in numerous flowers, including petunias and roses. However, little is known about the biosynthesis of these volatile compounds in plants. We have shown that the formation PHA and 2-phenylethanol from Phe does not occur via trans-cinnamic acid and instead competes with the key enzyme of phenypropanoid metabolism Pheammonia-lyase (PAL) for Phe utilization. Using functional genomic approach and comparative gene expression profiling, we have isolated and characterized a novel enzyme from petunia and rose flowers that catalyzes the formation of the Ca-Czcompound phenylacetaldehyde (PHA) from L-phenylalanine (Phe) by the removal of both the carboxyl and amino groups. This enzyme, designated as phenylacetaldehyde synthases (PAAS), is a bifunctional enzyme that catalyzes the unprecedented efficient coupling of phenylalanine decarboxylation to oxidation, generating phenylacetaldehyde, CO2, ammonia, and hydrogen peroxide in stoichiometric amounts. Down-regulation of PAAS expression via RNA interference-based (RNAi) technology in petunia resulted in no PHA emission when compared with controls. These plants also produced no 2-phenylethanol, supporting our conclusion that PHA is a precursor of 2-phenylethanol. To understand the regulation of scent formation in plants we have also generated transgenic petunia and tobacco plants expressing the rose alcohol acetyltransferase (RhAAT) gene under the control of a CaMV-35S promoter. Although the preferred substrate of RhAAT in vitro is geraniol, in transgenic petunia flowers, it used phenylethyl alcohol and benzyl alcohol to produce the corresponding acetate esters, not generated by control flowers. These results strongly point to the dependence of volatile production on substrate availability. Analysis of the diurnal regulation of scent production in rose flowers revealed that although the daily emission of most scent compounds is synchronized, various independently evolved mechanisms control the production, accumulation and release of different volatiles. This research resulted in a fundamental discovery of biochemical pathway, enzymes and genes involved in biosynthesis of C6-C2s compounds, and provided the knowledge for future engineering plants for improved scent quality.
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