Amino Acid Biosynthesis

Giacomo Deferrari, University of Genoa, Genoa, Italy
Irene Mannucci, University of Genoa, Genoa, Italy
Giacomo Garibotto, University of Genoa, Genoa, Italy

Published online: September 2010

DOI: 10.1002/9780470015902.a0000628.pub2

Amino acids are classically considered as the building blocks for the synthesis of proteins. Besides this, some of them play a major role in other functions, such as regulation of protein turnover and signal transduction, transport of nitrogen and carbon across the organs, or neurotransmission. The unique characteristics of amino acids are the presence of a free amino group in the -carbon and a free carboxyl group. The amino acids differ from each other with respect to their side-chains. The amino acids are classified into subgroups according to their similarity in carbon skeleton, substituent groups or a common metabolic pathway. The biosynthesis of amino acids involves several biochemical pathways in which amino acids are assembled from other precursors. The biosynthesis of amino acids is distinct from that involving lipids or carbohydrates because it includes the use of nitrogen.

Key Concepts:

  • Amino acids are classically considered as the building blocks from which proteins are synthesised. Besides this, some of them play a major role in the regulation of protein turnover and signal transduction, transport of nitrogen and carbon across the organs, and neurotransmission.
  • The biosynthesis of amino acids involves several biochemical pathways in which amino acids are assembled from other precursors. The biosynthesis of amino acids is distinct from that involving lipids or carbohydrates because it includes the use of nitrogen.
  • The fixation of nitrogen is a process that converts atmospheric nitrogen to a form that can be used biologically.
  • The pathways for the synthesis of essential amino acids are present only in microorganisms and plants.
  • Nine of 12 nonessential amino acids are synthesised from amphibolic intermediates, whereas three amino acids (tyrosine, cysteine and hydroxylysine) derive from essential amino acids. Amino acid transaminases, glutamate dehydrogenase and glutamine synthetase play a central role in the synthesis of nonessential amino acids.
  • The major pathway by which ammonia is incorporated into amino acids is through the reductive amination of -ketoglutarate to glutamate. Ammonia is highly toxic for animals. Glutamine is a nontoxic carrier of ammonia.
  • In the human adult as much as 200–250 g of proteins are degraded daily, and their constituent amino acids are in large part reutilised in protein synthesis.
  • Amino acid deficiency states can result if any of the essential amino acid is present in inadequate amounts or omitted from the diet.
  • Alanine, glutamate and glutamine are crucial links between energy and protein metabolism. Moreover, glutamine and alanine biosynthesis in the peripheral tissues (muscle) provides a means for the transport of carbon to the liver for gluconeogenesis and nitrogen for ureagenesis.
  • There are several nonprotein functions of amino acids, such as the biosynthesis of purines and pyrimidines, which involve more nonessential than essential amino acids.

Keywords: proteins; nutrition; nitrogen; carbon; ammonia

Figure 1. The nitrogen cycle.
Figure 2. Outline of pathways of synthesis of essential amino acids.
Figure 3. The hydroxylation of phenylalanine to tyrosine. From Scriver et al. (1995).
Figure 4. The reaction of glutamate dehydrogenase.
Figure 5. The reactions of glutaminase and glutamine synthetase.
Figure 6. Outline of pathways of synthesis of nonessential amino acids. Modified from Munro HM (ed.) (1969) Evolution of protein metabolism in mammals. In: Mammalian Protein Metabolism, vol. 3, pp. 133–182. New York: Academic Press.
Figure 7. Pathways of homocysteine–cysteine metabolism. THF, tetrahydrofolate; B12, vitamin B12 and B6, vitamin B6.
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 References
    Albrecht J and Norenberg MD (2006) Glutamine: a Trojan horse in ammonia neurotoxicity. Hepatology 44(4): 788–794.
    Bergen WG and Wu G (2009) Intestinal nitrogen recycling and utilization in health and disease. Journal of Nutrition 139(5): 821–825.
    Bier DM (1989) Intrinsically difficult problems: the kinetics of body proteins and amino acids in man. Diabetes/Metabolism Reviews 5: 111.
    Chesney RW, Helms RA, Christensen M et al. (1998) The role of taurine in infant nutrition. Advances in Experimental Medicine and Biology 442: 463–476.
    Endemann DH and Schiffrin EL (2004) Endothelial dysfunction. Journal of the American Society of Nephrology 15(8): 1983–1992.
    Felig P (1975) Amino acid metabolism in man. Annual Review of Biochemistry 44: 933–955.
    Fernstrom JD (2005) Branched-chain amino acids and brain function. Journal of Nutrition 135(6 suppl.): 1539S–1546S.
    Fürst P and Stehle P (2004) What are the essential elements needed for the determination of amino acid requirements in humans? Journal of Nutrition 134(6 suppl.): 1558S–1565S.
    Garibotto G, Tessari P, Verzola D and Dertenois L (2002) The metabolic conversion of phenylalanine into tyrosine in the human kidney: does it have nutritional implications in renal patients? Journal of Renal Nutrition 12(1): 8–16.
    Harper AE and Peters JC (1983) Amino acid signals and food intake and preference: relation to body protein metabolism. Experientia. Supplementum 44: 107–134.
    Kerbarh O, Bulloch EM, Payne RJ et al. (2005) Mechanistic and inhibition studies of chorismate-utilizing enzymes. Biochemical Society Transactions 33(part 4): 763–766.
    Krebs HA (1940) The citric acid cycle: a reply to the criticisms of F. L. Breusch and of J. Thomas. Biochemical Journal 34(3): 460–463.
    Liu Z, Jahn LA, Long W et al. (2001) Branched chain amino acids activate messenger ribonucleic acid translation regulatory proteins in human skeletal muscle, and glucocorticoids blunt this action. Journal of Clinical Endocrinology and Metabolism 86(5): 2136–2143.
    Lobanov AV, Kryukov GV, Hatfield DL and Gladyshev VN (2006) Is there a twenty third amino acid in the genetic code? Trends in Genetics 22(7): 357–360.
    book Munro HC and Crim MC (1988) "The proteins and amino acids". In: Shils ME and Young VR (eds) Modern Nutrition in Health and Disease, pp. 1–37. Philadelphia, PA: Lea Febiger.
    Palaiologos G and Felig P (1976) Effects of ketone bodies on amino acid metabolism in isolated rat diaphragm. Biochemical Journal 154(3): 709–716.
    Pellett PL and Ghosh S (2004) Lysine fortification: past, present, and future. Food and Nutrition Bulletin 25(2): 107–113.
    Pui CH and Evans WE (2006) Treatment of acute lymphoblastic leukemia. New England Journal of Medicine 354(2): 166–178.
    Reynolds PE and Courvalin P (2005) Vancomycin resistance in enterococci due to synthesis of precursors terminating in d-alanyl-d-serine. Antimicrobial Agents and Chemotherapy 49(1): 21–25.
    Rose WC (1937) The nutritive significance of the amino acids and certain related compounds. Science 86(2231): 298–300.
    Rose WC, Haines WJ and Warner DT (1954) The amino acid requirements of man. V. The rôle of lysine, arginine, and tryptophan. Journal of Biological Chemistry 206(1): 421–430.
    Roth E (2008) Nonnutritive effects of glutamine. Journal of Nutrition 138(10): 2025S–2031S.
    book Scriver CR, Beaudet AL, Sly WS et al. (1995) The Metabolic and Molecular Bases of Inherited Disease, 7th edn, chaps 27–38. New York: McGraw-Hill.
    Stühlinger MC, Tsao PS, Her JH et al. (2002) Homocysteine impairs the nitric oxide synthase pathway: role of asymmetric dimethylarginine. Circulation 104(21): 2569–2575.
    Stumvoll M, Meyer C, Perriello G et al. (1998) Human kidney and liver gluconeogenesis: evidence for organ substrate selectivity. American Journal of Physiology 274: E817–E826.
    Tessari P, Deferrari G, Robaudo C et al. (1999) Phenylalanine hydroxylation across the kidney in humans. Kidney International 56: 2168–2172.
    Tessari P, Vettore M, Millioni R, Puricelli L and Orlando R (2010) Effect of liver cirrhosis on phenylalanine and tyrosine metabolism. Current Opinion in Clinical Nutrition and Metabolic Care 13(1): 81–86.
    Tizianello A, Deferrari G, Garibotto G et al. (1983) Branched-chain amino acid metabolism in chronic renal failure. Kidney International. Supplement 16: S17–S22.
    Tizianello A, Deferrari G, Garibotto G, Robaudo C and Gurreri G (1980) Renal metabolism of amino acids and ammonia in subjects with normal renal function and in patients with chronic renal insufficiency. Journal of Clinical Investigation 65: 1162–1171.
    Waterlow JC (1984) Protein turnover with special reference to man. Quarterly Journal of Experimental Physiology 69(3): 409–438.
    Welch GN and Loscalzo J (1998) Homocysteine and atherothrombosis. New England Journal of Medicine 338(15): 1042–1050.
    Young VR and Sudir B (1999) Adult human amino acid requirements. Current Opinion in Clinical Nutrition and Metabolic Care 2: 39–45.
 Further Reading
    Deferrari G, Garibotto G, Robaudo C et al. (1994) Renal ammoniagenesis and interorgan flow of glutamine in chronic metabolic acidosis. Contributions to Nephrology 110: 144–149.
    Garibotto G, Valli A, Anderstam B et al. (2009) The kidney is a major site of S-adenosylhomocysteine disposal in humans. Kidney International 76: 293–296.
    Heinemann IU, O'Donoghue P, Madinger C et al. (2009) The appearance of pyrrolysine in tRNAH is guanylyltransferase by neutral evolution. Proceedings of the National Academy of Sciences of the USA 106: 21103–21108.
    Meijer AJ, Lamers WH and Chamuleau RAFM (1990) Nitrogen metabolism and ornithine cycle function. Physiological Reviews 70: 701–748.
    Reeds PJ, Burrin DG, Davis T and Stoll B (1998) Amino acid metabolism and the energetics of growth. Archives of Animal Nutrition 51: 187–197.
    Rose WC (1957) The amino acid requirements of adult man. Nutrition Abstracts and Reviews 27: 631–647.
    Tessari P and Garibotto G (2000) Inter-organ amino acid exchange. Current Opinion in Clinical Nutrition and Metabolic Care 3: 51–57.

Related Sub-Topics:

Growth and Synthesis | Proteins: Structure, Function, Metabolism | Other Biomolecules: Structure, Function, Metabolism
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Article Title: Amino Acid Biosynthesis
 
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Deferrari, Giacomo, Mannucci, Irene, and Garibotto, Giacomo(Sep 2010) Amino Acid Biosynthesis. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0000628.pub2]