Aspartate transaminase - Wikipedia. Aspartate transaminase (AST) or aspartate aminotransferase, also known as Asp. AT/ASAT/AAT or serum glutamic oxaloacetic transaminase (SGOT), is a pyridoxal phosphate (PLP)- dependent transaminase enzyme (EC2. Arthur Karmen and colleagues in 1. AST is found in the liver, heart, skeletal muscle, kidneys, brain, and red blood cells. Serum AST level, serum ALT (alanine transaminase) level, and their ratio (AST/ALT ratio) are commonly measured clinically as biomarkers for liver health. The tests are part of blood panels. Function. In the process, the cofactor shuttles between PLP and the pyridoxamine phosphate (PMP) form. In amino acid degradation, following the conversion of . In the reverse reaction, aspartate may be synthesized from oxaloacetate, which is a key intermediate in the citric acid cycle. In humans: These isoenzymes are thought to have evolved from a common ancestral AST via gene duplication, and they share a sequence homology of approximately 4. AST is dimeric, consisting of two identical subunits, each with approximately 4. D. The large domain, which includes residues 4. PLP cofactor via an aldimine linkage to the . Other residues in this domain – Asp 2. Tyr 2. 25 – also interact with PLP via hydrogen bonding. The small domain consists of residues 1. Within each active site, a couple arginine residues are responsible for the enzyme’s specificity for dicarboxylic acid substrates: Arg. Each domain has a central sheet of . In the first half- reaction, amino acid 1 (e. L- Asp) reacts with the enzyme- PLP complex to generate ketoacid 1 (oxaloacetate) and the modified enzyme- PMP. In the second half- reaction, ketoacid 2 (. Formation of a racemic product (D- Glu) is very rare. This transaldimination reaction occurs via a nucleophilic attack by the deprotonated amino group of Asp and proceeds through a tetrahedral intermediate. As this point, the carboxylate groups of Asp are stabilized by the guanidinium groups of the enzyme’s Arg. An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. AST is normally found in red blood cells, the liver, heart, pancreas.Arg 2. 92 residues. Quinonoid formation: The hydrogen attached to the a- carbon of Asp is then abstracted (Lys. Ketimine formation: The quinonoid is reprotonated, but now at the aldehyde carbon, to form the ketimine intermediate. Ketimine hydrolysis: Finally, the ketimine is hydrolyzed to form PMP and oxaloacetate. This mechanism is thought to have multiple partially rate- determining steps. The difference is that ALT is found predominantly in the liver, with clinically negligible quantities found in the kidneys, heart, and skeletal muscle, while AST is found in the liver, heart (cardiac muscle), skeletal muscle, kidneys, brain, and red blood cells. However, the use of AST for such a diagnosis is now redundant and has been superseded by the cardiac troponins. However, it is important to keep in mind that the source of AST (and, to a lesser extent, ALT) in blood tests may reflect pathology in organs other than the liver. In fact, when the AST is higher than ALT, a muscle source of these enzymes should be considered. For example, muscle inflammation due to dermatomyositis may cause AST> ALT. This is a good reminder that AST and ALT are not good measures of liver function because they do not reliably reflect the synthetic ability of the liver and they may come from tissues other than liver (such as muscle). Laboratory tests should always be interpreted using the reference range from the laboratory that performed the test. Example reference ranges are shown below: See also. Protein Eng. 7 (3): 4. PMID 7. 90. 99. 46. The Journal of Clinical Investigation. PMC 4. 38. 59. 4 . PMID 1. 32. 21. 66. The Journal of Clinical Investigation. PMC 4. 38. 59. 4 . PMID 1. 32. 21. 66. PMID 1. 31. 95. 68. PMID 6. 14. 38. 29. Biochemistry. ISBN 9. Annu Rev Biochem. PMID 2. 19. 79. 92. 7 Oxidation of Glutamate Write a series of balanced. Nutrient Metabolism. To the biosynthetic precursor aspartate by the action of glutamate aspartate. PMC 1. 15. 14. 61 . PMID 1. 90. 91. 12. PMID 8. 90. 71. 87. ChronicAlcohol Induces M2PolarizationEnhancing PulmonaryDisease CausedbyExposureto ParticulateAir. J Bacteriol. 1. 30 (1): 4. PMC 2. 35. 22. 1 . PMID 1. 59. 36. 33. J Biol Chem. 2. 72 (2. PMID 9. 21. 18. 66. PMID 3. 07. 15. 27. Biochemistry. 3. 0 (7): 1. PMID 1. 99. 32. 08. PMID 1. 52. 25. 85. PMID 1. 58. 89. 41. Eur J Biochem. 2. PMID 1. 73. 54. 41. Biochemistry. 3. 5 (1. PMID 8. 61. 15. 15. J Biol Chem. 2. 78 (1. PMID 1. 24. 88. 44. Current Opinion in Investigational Drugs. PMID 1. 77. 29. 18. Jurnak FA and Mc. Pherson A, eds. Structural basis for catalysis by aspartate aminotransferase (Biological Macromolecules and Assemblies, Vol. New York: Wiley. ISBN 0- 4. Kuramitsu S, Okuno S, Ogawa T, Ogawa H, Kagamiyama H (1. PMID 3. 89. 72. 10. Kondo K, Wakabayashi S, Yagi T, Kagamiyama H (1. PMID 6. 37. 82. 05. Inoue K, Kuramitsu S, Okamoto A, Hirotsu K, Higuchi T, Kagamiyama H (1. Biochemistry. 3. 0 (3. PMID 1. 86. 80. 57. How to reduce alanine transaminase.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
September 2017
Categories |