title: Active-site-directed irreversible inhibition of rat brain 4-aminobutyrate aminotransferase by ethanolamine O-sulphate in vitro and in vivo.
abstract: 1. Partially purified preparations of rat brain 4-aminobutyrate aminotransferase were inhibited in a time-dependent manner by ethanolamine O-sulphate. The inhibition was not reversed by dialysis. 2. The inhibitor formed an initial reversible complex with the enzyme (K(i)=4.4x10(-4)m) and the rate of inactivation followed pseudo-first-order kinetics (k=7.15x10(-4)s(-1)). The inclusion of 4-aminobutyrate markedly slowed the rate of inactivation. 3. Ethanolamine O-sulphate did not inhibit glutamate decarboxylase, alanine aminotransferase or aspartate aminotransferase. 4. Intracisternal injection of ethanolamine O-sulphate into rats led to rapid inactivation of 4-aminobutyrate aminotransferase in vivo.
mesh_terms: D000613:Aminobutyrates; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002552:Cerebral Ventricles; D003956:Dialysis; D004983:Ethanolamines / Q000008:administration & dosage / Q000494:pharmacology*; D007267:Injections; D007700:Kinetics; D051381:Rats; D013431:Sulfates / Q000008:administration & dosage / Q000494:pharmacology*; D000637:Transaminases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification
chemical_list: D000613:Aminobutyrates; D004983:Ethanolamines; D013431:Sulfates; D000637:Transaminases