Aspartate transaminase

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Aspartate aminotransferase
Aspartate aminotransferase. Aspartate aminotransferase from Escherichia coli bound with cofactor pyridoxal 5-phosphate (PDB 1AAM)
Genetic data
Gene code:	[1] ID#: GI:41011
Protein Structure/Function
Structure:	[2]1AAM

Aspartate transaminase (AST) also called serum glutamic oxaloacetic transaminase (SGOT) or aspartate aminotransferase (ASAT/AAT) (EC 2.6.1.1) is similar to alanine transaminase (ALT) in that it is another enzyme associated with liver parenchymal cells.

Contents 1 Function 2 Isozymes 3 Clinical significance 4 References 5 Journal articles 6 External links

[edit] Function

It facilitates the conversion of aspartate and alpha-ketoglutarate to oxaloacetate and glutamate.

[edit] Isozymes

Two isoenzymes are present in humans. They have high similarity.

• GOT1, the cytosolic isoenzyme derives mainly from red blood cells and heart.
• GOT2, the mitochondrial isoenzyme is predominantly present in liver.

[edit] Clinical significance

It is raised in acute liver damage. It is also present in red blood cells and cardiac muscle, skeletal muscle, and kidney and brain tissue, and may be elevated due to damage to those sources as well.

AST was defined as a biochemical marker for the diagnosis of acute myocardial infarction in 1954. However the use of AST for such a diagnosis is now redundant and has been superseded by the cardiac troponins.^[1]

AST (SGOT) is commonly measured clinically as a part of diagnostic liver function tests, to determine liver health.

[edit] References

[edit] Journal articles

• Kuramitsu S, Okuno S, Ogawa T, Ogawa H, Kagamiyama H (1985). "Aspartate aminotransferase of Escherichia coli: nucleotide sequence of the aspC gene". J. Biochem. 97 (4): 1259-62. PMID 3897210. 

• Kondo K, Wakabayashi S, Yagi T, Kagamiyama H (1984). "The complete amino acid sequence of aspartate aminotransferase from Escherichia coli: sequence comparison with pig isoenzymes". Biochem. Biophys. Res. Commun. 122 (1): 62-7. doi:10.1016/0006-291X(84)90439-X. PMID 6378205. 

• Inoue K, Kuramitsu S, Okamoto A, Hirotsu K, Higuchi T, Kagamiyama H (1991). "Site-directed mutagenesis of Escherichia coli aspartate aminotransferase: role of Tyr70 in the catalytic processes". Biochemistry 30 (31): 7796-801. doi:10.1021/bi00245a019. PMID 1868057. 

[edit] External links

• MeSH Aspartate+Transaminase

v • d • e Transferase: transaminases (EC 2.6) Aspartate transaminase - Alanine transaminase - GABA transaminase - Tyrosine aminotransferase - Ornithine aminotransferase - Branched chain aminotransferase

v • d • e Mitochondrial enzymes and transporters Outer membrane fatty acid degradation (Carnitine palmitoyltransferase I, Long fatty acyl CoA synthetase) tryptophan metabolism (Kynureninase) monoamine neurotransmitter metabolism (Monoamine oxidase) Intermembrane space Adenylate kinase - Creatine kinase Inner membrane oxidative phosphorylation (Coenzyme Q - cytochrome c reductase, Cytochrome c, NADH dehydrogenase, Succinate dehydrogenase) pyrimidine metabolism (Dihydroorotate dehydrogenase) mitochondrial shuttle (Malate-aspartate shuttle, Glycerol phosphate shuttle) other (Glutamate aspartate transporter, Glycerol-3-phosphate dehydrogenase, ATP synthase, Carnitine palmitoyltransferase II) Matrix citric acid cycle (Citrate synthase, Aconitase, Isocitrate dehydrogenase, Oxoglutarate dehydrogenase, Succinyl coenzyme A synthetase, Fumarase, Malate dehydrogenase) anaplerotic reactions (Aspartate transaminase, Glutamate dehydrogenase, Pyruvate dehydrogenase complex) urea cycle (Carbamoyl phosphate synthetase I, Ornithine transcarbamylase, N-Acetylglutamate synthase) alcohol metabolism (ALDH2) Other/to be sorted Cholesterol side-chain cleavage enzyme Mitochondrial DNA Complex I (7 units) - Complex III (1 unit) - Complex IV (3 units) - ATP synthase (2 units)

v • d • e Metabolism: Citric acid cycle enzymes Cycle Citrate synthase - Aconitase - Isocitrate dehydrogenase - Oxoglutarate dehydrogenase - Succinyl CoA synthetase Succinate dehydrogenase (SDHA) - Fumarase - Malate dehydrogenase Anaplerotic to acetyl-CoA: Pyruvate dehydrogenase complex (regulated by Pyruvate dehydrogenase kinase and Pyruvate dehydrogenase phosphatase) to ketoglutaric acid: Glutamate dehydrogenase to succinyl-CoA: Methylmalonyl-CoA mutase to oxaloacetate: Pyruvate carboxylase - Aspartate transaminase

v • d • e Metabolism: amino acid metabolism - synthesis and catabolism enzymes (essential in CAPS) K→acetyl-CoA LYSINE→ Saccharopine dehydrogenase - Glutaryl-CoA dehydrogenase LEUCINE→ Branched chain aminotransferase - Branched-chain alpha-keto acid dehydrogenase complex - Isovaleryl coenzyme A dehydrogenase - Methylcrotonyl-CoA carboxylase - Methylglutaconyl-CoA hydratase - 3-hydroxy-3-methylglutaryl-CoA lyase TRYPTOPHAN→ Indoleamine 2,3-dioxygenase/Tryptophan 2,3-dioxygenase - Arylformamidase - Kynureninase - 3-hydroxyanthranilate oxidase - Aminocarboxymuconate-semialdehyde decarboxylase - Aminomuconate-semialdehyde dehydrogenase PHENYLALANINE→tyrosine→ (see below) G→pyruvate glycine→serine→ Serine hydroxymethyltransferase - Serine dehydratase alanine→ Alanine transaminase cysteine→ D-cysteine desulfhydrase threonine→ L-threonine dehydrogenase G→glutamate HISTIDINE→ Histidine ammonia-lyase - Urocanate hydratase - Formiminotransferase cyclodeaminase proline→ Proline oxidase - Pyrroline-5-carboxylate reductase - 1-Pyrroline-5-carboxylate dehydrogenase/ALDH4A1 - PYCR1 arginine→ Ornithine aminotransferase - Ornithine decarboxylase - Agmatinase →alpha-ketoglutarate→TCA Glutamate dehydrogenase G→propionyl-CoA VALINE→ Branched chain aminotransferase - Branched-chain alpha-keto acid dehydrogenase complex - Enoyl-CoA hydratase - 3-hydroxyisobutyryl-CoA hydrolase - 3-hydroxyisobutyrate dehydrogenase - Methylmalonate semialdehyde dehydrogenase ISOLEUCINE→ Branched chain aminotransferase - Branched-chain alpha-keto acid dehydrogenase complex - 3-hydroxy-2-methylbutyryl-CoA dehydrogenase METHIONINE→ Methionine adenosyltransferase - Adenosylhomocysteinase - Cystathionine beta synthase - Cystathionine gamma-lyase (methionine synthesis: MTR/Homocysteine methyltransferase) THREONINE→ Threonine aldolase →succinyl-CoA→TCA Propionyl-CoA carboxylase - Methylmalonyl-CoA mutase G→fumarate PHENYLALANINE→tyrosine→ Phenylalanine hydroxylase - Tyrosine aminotransferase - 4-Hydroxyphenylpyruvate dioxygenase - Homogentisate 1,2-dioxygenase - Fumarylacetoacetate hydrolase G→oxaloacetate asparagine→aspartate→ Asparaginase/Asparagine synthetase - Aspartate transaminase Other tyrosine→melanin Tyrosinase cysteine+glutamate→glutathione Gamma-glutamylcysteine synthetase - Glutathione synthetase - Gamma-glutamyl transpeptidase glycine→creatine Guanidinoacetate N-methyltransferase - Creatine kinase glutamate→glutamine Glutamine synthetase - Glutaminase proline+lysine→collagen Prolyl hydroxylase - Lysyl hydroxylase see also disorders, intermediates