An amino acid contains an amino (NH2) group. A keto acid contains a keto (=O) group. In transamination, the NH2 group on one molecule is exchanged with the =O group on the other molecule. The amino acid becomes a keto acid, and the keto acid becomes an amino acid.[citation needed]
Transaminases require the coenzyme pyridoxal phosphate, which is converted into pyridoxamine in the first half-reaction, when an amino acid is converted into a keto acid. Enzyme-bound pyridoxamine in turn reacts with pyruvate, oxaloacetate, or alpha-ketoglutarate, giving alanine, aspartic acid, or glutamic acid, respectively. Many transamination reactions occur in tissues, catalysed by transaminases specific for a particular amino/keto acid pair. The reactions are readily reversible, the direction being determined by which of the reactants are in excess. This reversibility can be exploited for synthetic chemistry applications to achieve the synthesis of valuable chiral amines. The specific enzymes are named from one of the reactant pairs, for example; the reaction between glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is called alanine transaminase and was originally called glutamic-pyruvic transaminase or GPT for short.[1]
Tissue transaminase activities can be investigated by incubating a homogenate with various amino/keto acid pairs. Transamination is demonstrated if the corresponding new amino acid and keto acid are formed, as revealed by paper chromatography. Reversibility is demonstrated by using the complementary keto/amino acid pair as starting reactants. After chromatogram has been taken out of the solvent the chromatogram is then treated with ninhydrin to locate the spots.[citation needed].
Aminotransfer reaction between an amino acid and an alpha-keto acid. The amino (NH2) group and the keto (=O) group are exchanged.
Amino acid metabolism in animalsedit
Animals must metabolize proteins to amino acids, at the expense of muscle tissue, when blood sugar is low. The preference of liver transaminases for oxaloacetate or alpha-ketoglutarate plays a key role in funneling nitrogen from amino acid metabolism to aspartate and glutamate for conversion to urea for excretion of nitrogen. In similar manner, in muscles the use of pyruvate for transamination gives alanine, which is carried by the bloodstream to the liver (the overall reaction being termed glucose-alanine cycle). Here other transaminases regenerate pyruvate, which provides a valuable precursor for gluconeogenesis. This alanine cycle is analogous to the Cori cycle, which allows anaerobic metabolism by muscles.[citation needed]
Diagnostic usesedit
The transaminase enzymes are important in the production of various amino acids, and measuring the concentrations of various transaminases in the blood is important in the diagnosing and tracking many diseases.[citation needed] For example, the presence of elevated transaminases can be an indicator of liver and cardiac damage. Two important transaminase enzymes are aspartate transaminase (AST), also known as serum glutamic oxaloacetic transaminase (SGOT); and alanine transaminase (ALT), also called alanine aminotransferase (ALAT) or serum glutamate-pyruvate transaminase (SGPT). These transaminases were discovered in 1954[1][2][3] and their clinical importance was described in 1955.[4][5][6][7]
^ abKarmen A, Wroblewski F, Ladue JS (January 1955). "Transaminase activity in human blood". The Journal of Clinical Investigation. 34 (1): 126–31. doi:10.1172/jci103055. PMC438594. PMID 13221663.
^Karmen A (January 1955). "A note on the spectrometric assay of glutamic-oxalacetic transaminase in human blood serum". The Journal of Clinical Investigation. 34 (1): 131–3. doi:10.1172/JCI103055. PMC438594. PMID 13221664.
^Ladue JS, Wroblewski F, Karmen A (September 1954). "Serum glutamic oxaloacetic transaminase activity in human acute transmural myocardial infarction". Science. 120 (3117): 497–9. Bibcode:1954Sci...120..497L. doi:10.1126/science.120.3117.497. PMID 13195683.
^"Biblioteca Nazionale di Napoli. News: Serata in onore di Mario Coltorti e Giuseppe Giusti". vecchiosito.bnnonline.it. Retrieved 2017-09-10.
^"E' morto il prof. Coltorti: scoprì le transaminasi". notizie-segreteria-liver-pool.blogspot.it. Retrieved 2017-09-10.
^"Campania su Coltorti". www.istitutobioetica.org. Retrieved 2017-09-10.
^MonrifNet (3 January 2009). "Il Resto Del Carlino - Macerata - E' morto Mario Coltorti: scoprì la transaminasi". www.ilrestodelcarlino.it (in Italian). Retrieved 2017-09-10.
Further readingedit
Ghany M, Hoofnagle JH (2005). "Approach to the Patient With Liver Disease". In Kasper DL, Fauci AS, Longo DL, Braunwald E, Hauser SL, Jameson JL (eds.). Harrison's Principles of Internal Medicine (16th ed.). New York: McGraw-Hill. pp. 1814–5.
Nelson DL, Cox MM (2000). Lehninger Principles of Biochemistry (3rd ed.). New York: Worth Publishers. pp. 628–31, 634, 828–30.
transaminase, aminotransferases, enzymes, that, catalyze, transamination, reaction, between, amino, acid, keto, acid, they, important, synthesis, amino, acids, which, form, proteins, aminotransferaseaspartate, transaminase, from, coli, with, pyridoxal, phospha. Transaminases or aminotransferases are enzymes that catalyze a transamination reaction between an amino acid and an a keto acid They are important in the synthesis of amino acids which form proteins AminotransferaseAspartate transaminase from E coli with Pyridoxal 5 Phosphate cofactorIdentifiersSymbolAminotransferasePfamPF00155InterProIPR004839Membranome273Available protein structures Pfam structures ECOD PDBRCSB PDB PDBe PDBjPDBsumstructure summary Contents 1 Function and mechanism 2 Amino acid metabolism in animals 2 1 Diagnostic uses 3 See also 4 References 5 Further reading 6 External linksFunction and mechanism editAn amino acid contains an amino NH2 group A keto acid contains a keto O group In transamination the NH2 group on one molecule is exchanged with the O group on the other molecule The amino acid becomes a keto acid and the keto acid becomes an amino acid citation needed Transaminases require the coenzyme pyridoxal phosphate which is converted into pyridoxamine in the first half reaction when an amino acid is converted into a keto acid Enzyme bound pyridoxamine in turn reacts with pyruvate oxaloacetate or alpha ketoglutarate giving alanine aspartic acid or glutamic acid respectively Many transamination reactions occur in tissues catalysed by transaminases specific for a particular amino keto acid pair The reactions are readily reversible the direction being determined by which of the reactants are in excess This reversibility can be exploited for synthetic chemistry applications to achieve the synthesis of valuable chiral amines The specific enzymes are named from one of the reactant pairs for example the reaction between glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is called alanine transaminase and was originally called glutamic pyruvic transaminase or GPT for short 1 Tissue transaminase activities can be investigated by incubating a homogenate with various amino keto acid pairs Transamination is demonstrated if the corresponding new amino acid and keto acid are formed as revealed by paper chromatography Reversibility is demonstrated by using the complementary keto amino acid pair as starting reactants After chromatogram has been taken out of the solvent the chromatogram is then treated with ninhydrin to locate the spots citation needed nbsp Aminotransfer reaction between an amino acid and an alpha keto acid The amino NH2 group and the keto O group are exchanged Amino acid metabolism in animals editAnimals must metabolize proteins to amino acids at the expense of muscle tissue when blood sugar is low The preference of liver transaminases for oxaloacetate or alpha ketoglutarate plays a key role in funneling nitrogen from amino acid metabolism to aspartate and glutamate for conversion to urea for excretion of nitrogen In similar manner in muscles the use of pyruvate for transamination gives alanine which is carried by the bloodstream to the liver the overall reaction being termed glucose alanine cycle Here other transaminases regenerate pyruvate which provides a valuable precursor for gluconeogenesis This alanine cycle is analogous to the Cori cycle which allows anaerobic metabolism by muscles citation needed Diagnostic uses edit The transaminase enzymes are important in the production of various amino acids and measuring the concentrations of various transaminases in the blood is important in the diagnosing and tracking many diseases citation needed For example the presence of elevated transaminases can be an indicator of liver and cardiac damage Two important transaminase enzymes are aspartate transaminase AST also known as serum glutamic oxaloacetic transaminase SGOT and alanine transaminase ALT also called alanine aminotransferase ALAT or serum glutamate pyruvate transaminase SGPT These transaminases were discovered in 1954 1 2 3 and their clinical importance was described in 1955 4 5 6 7 See also editValproic acid a GABA transaminase inhibitorReferences edit a b Karmen A Wroblewski F Ladue JS January 1955 Transaminase activity in human blood The Journal of Clinical Investigation 34 1 126 31 doi 10 1172 jci103055 PMC 438594 PMID 13221663 Karmen A January 1955 A note on the spectrometric assay of glutamic oxalacetic transaminase in human blood serum The Journal of Clinical Investigation 34 1 131 3 doi 10 1172 JCI103055 PMC 438594 PMID 13221664 Ladue JS Wroblewski F Karmen A September 1954 Serum glutamic oxaloacetic transaminase activity in human acute transmural myocardial infarction Science 120 3117 497 9 Bibcode 1954Sci 120 497L doi 10 1126 science 120 3117 497 PMID 13195683 Biblioteca Nazionale di Napoli News Serata in onore di Mario Coltorti e Giuseppe Giusti vecchiosito bnnonline it Retrieved 2017 09 10 E morto il prof Coltorti scopri le transaminasi notizie segreteria liver pool blogspot it Retrieved 2017 09 10 Campania su Coltorti www istitutobioetica org Retrieved 2017 09 10 MonrifNet 3 January 2009 Il Resto Del Carlino Macerata E morto Mario Coltorti scopri la transaminasi www ilrestodelcarlino it in Italian Retrieved 2017 09 10 Further reading editGhany M Hoofnagle JH 2005 Approach to the Patient With Liver Disease In Kasper DL Fauci AS Longo DL Braunwald E Hauser SL Jameson JL eds Harrison s Principles of Internal Medicine 16th ed New York McGraw Hill pp 1814 5 Nelson DL Cox MM 2000 Lehninger Principles of Biochemistry 3rd ed New York Worth Publishers pp 628 31 634 828 30 External links editTransaminases at the U S National Library of Medicine Medical Subject Headings MeSH Portal nbsp Biology Retrieved from https en wikipedia org w index php title Transaminase amp oldid 1191461140, wikipedia, wiki, book, books, library,
