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Aspartate transaminase

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

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.

Function

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

Isozymes

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

Clinical significance

It is raised in acute liver damage. It is also present in red blood cells and cardiac muscle.

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 However the use of AST for such a diagnosis is now redundant and has been superseded by the cardiac troponins.[1]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 / ALT is commonly measured clinically as a part of a diagnostic liver function test, to determine liver health. This is because of hepatic deficiency of pyrodoxal-6-phosphate in alcoholics, which is a cofactor for the enzymatic activity of ALT.

Differential Diagnosis of Causes of Elevated AST

References

  1. Gaze DC (2007). “The role of existing and novel cardiac biomarkers for cardioprotection”. Curr. Opin. Invest. Drugs. 8 (9): 711–717. PMID 17729182.
  • 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. 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. PMID 1868057.



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