Abstract
Gabaculine, 5-amino-1,3-cyclohexadienylcarboxylate, is an analogue of GABA and a potent irreversible inhibitor of GABA aminotransferase. However, D-3-aminoisobutyrate-pyruvate aminotransferase for which GABA was neither a substrate nor an inhibitor was also inactivated by gabaculine. The Ki for D-3-aminoisobutyrate-pyruvate aminotransferase was 8.3 x 10(-6) M, and the Kcat for its turnover was 0.31 min-1 at 25 degrees C. beta-Alanine protected the enzyme from inactivation by gabaculine, but GABA did so to much a lesser extent.
MeSH terms
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4-Aminobutyrate Transaminase / antagonists & inhibitors
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Alanine Transaminase / antagonists & inhibitors
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Alanine Transaminase / isolation & purification
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Animals
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Cyclohexanecarboxylic Acids / pharmacology*
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Isoenzymes / antagonists & inhibitors
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Kinetics
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Liver / enzymology
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Pseudomonas fluorescens / enzymology
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Rats
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Transaminases / antagonists & inhibitors*
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beta-Alanine / pharmacology
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gamma-Aminobutyric Acid / pharmacology
Substances
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Cyclohexanecarboxylic Acids
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Isoenzymes
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beta-Alanine
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gabaculine
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gamma-Aminobutyric Acid
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Transaminases
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4-Aminobutyrate Transaminase
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Alanine Transaminase
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D-3-aminoisobutyrate-pyruvate aminotransferase