Aspartate transaminase: Definition from Answers.com

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.

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

Function

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

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.

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 However the use of AST for such a diagnosis is now redundant and has been superseded by the cardiac troponins.^[1]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.

References

^ Gaze DC (2007). "The role of existing and novel cardiac biomarkers for cardioprotection". Curr. Opin. Invest. Drugs 8 (9): 711–717. PMID 17729182.

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.

External links

MeSH Aspartate+Transaminase

v • d • e Transferase: Nitrogenous groups (EC 2.6)

2.6.1: Transaminases	Aspartate transaminase (GOT1, GOT2) · Alanine transaminase · GABA transaminase · Tyrosine aminotransferase · Ornithine aminotransferase · Branched chain aminotransferase

2.6.3: Oximinotransferases	Oximinotransferase

2.6.99: Other	Pyridoxine 5'-phosphate synthase

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, Uncoupling protein)

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	steroidogenesis (Cholesterol side-chain cleavage enzyme, Steroid 11-beta-hydroxylase, Aldosterone synthase)

Mitochondrial DNA	Complex I (MT-ND1, MT-ND2, MT-ND3, MT-ND4, MT-ND4L, MT-ND5, MT-ND6) - Complex III (MT-CYB) - Complex IV (MT-CO1, MT-CO2, MT-CO3) ATP synthase (MT-ATP6, MT-ATP8) tRNA (MT-TA, MT-TC, MT-TD, MT-TE, MT-TF, MT-TG, MT-TH, MT-TI, MT-TK, MT-TL1, MT-TL2, MT-TM, MT-TN, MT-TP, MT-TQ, MT-TR, MT-TS1, MT-TS2, MT-TT, MT-TV, MT-TW, MT-TY)

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 (E1, E2, E3) (regulated by Pyruvate dehydrogenase kinase and Pyruvate dehydrogenase phosphatase)

to α-ketoglutaric acid	Glutamate dehydrogenase

to succinyl-CoA	Methylmalonyl-CoA mutase

to oxaloacetate	Pyruvate carboxylase · Aspartate transaminase

see also intermediates

Metabolism: amino acid metabolism · synthesis and catabolism enzymes (essential in CAPS)

K→acetyl-CoA

G→pyruvate
→citrate

glycine→serine→	Serine hydroxymethyltransferase · Serine dehydratase glycine→creatine: Guanidinoacetate N-methyltransferase · Creatine kinase

alanine→	Alanine transaminase

cysteine→	D-cysteine desulfhydrase

threonine→	L-threonine dehydrogenase

G→glutamate→
α-ketoglutarate

G→propionyl-CoA→
succinyl-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→	generation of homocysteine: Methionine adenosyltransferase · Adenosylhomocysteinase regeneration of methionine: MTR/Homocysteine methyltransferase · Betaine-homocysteine methyltransferase conversion to cysteine: Cystathionine beta synthase · Cystathionine gamma-lyase

THREONINE→	Threonine aldolase

→succinyl-CoA→TCA	Propionyl-CoA carboxylase · Methylmalonyl CoA epimerase · Methylmalonyl-CoA mutase

G→fumarate


PHENYLALANINE→tyrosine→	Phenylalanine hydroxylase · Tyrosine aminotransferase · 4-Hydroxyphenylpyruvate dioxygenase · Homogentisate 1,2-dioxygenase · Fumarylacetoacetate hydrolase tyrosine→melanin: Tyrosinase

G→oxaloacetate


asparagine→aspartate→	Asparaginase/Asparagine synthetase · Aspartate transaminase

see also disorders, intermediates

Serology, reference range: blood tests

Clinical biochemistry

Metabolic panel	BMP: electrolytes (Na⁺/K⁺, Cl^-/HCO₃^-) · renal function, BUN-to-creatinine ratio (BUN/Creatinine) · Glucose · Ca CMP: BMP + protein tests (Human serum albumin, Serum total protein) · liver function tests (ALP, ALT, AST, Bilirubin) derived values: Plasma osmolality · Serum osmolal gap

Acid-base homeostasis	Arterial blood gas · Base excess · Anion gap · CO2 content

Iron tests	Transferrin saturation = Serum iron / Total iron-binding capacity Ferritin · Transferrin · Transferrin receptor

Blood sugar	Glucose test · Glucose tolerance test · Glycemia · Noninvasive glucose · C-peptide · Fructosamine · Random glucose test · Glycosylated hemoglobin

Endocrine	ACTH stimulation test · Thyroid function tests

Cardiac marker	Troponin test · CPK-MB test · Glycogen phosphorylase isoenzyme BB

Other	Beutler test · MELISA · RAST test · Blood lipids · Tumor marker

Hematology

Clotting	vWF: Ristocetin induced platelet agglutination clotting factors: Prothrombin time · Partial thromboplastin time · Thrombin time other/general coagulation: Bleeding time · animal enzyme (Reptilase time, Ecarin clotting time, Dilute Russell's viper venom time) · Thromboelastography fibrinolysis: Euglobulin lysis time · D-dimer

CBC/Red blood cell indices	Hematocrit · Hemoglobin · RBC count ratios: Mean corpuscular hemoglobin · Mean corpuscular hemoglobin concentration · Mean corpuscular volume Fetal hemoglobin: Apt-Downey test · Kleihauer-Betke test · Red blood cell distribution width

Other	Blood film · Reticulocyte index · Blood viscosity · Absolute neutrophil count · Haptoglobin

Immunology

see also reference ranges for blood tests

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Aspartate transaminase

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