ATP-Dependent Inactivation of Escherichia coli γ-Glutamylcysteine Synthetase by L-Glutamic Acid γ-Monohydroxamate

Abstract

  Incubation of Escherichia coli γ-glutamylcysteine synthetase with L-glutamic acid γ-monohydroxamate and ATP caused slow but irreversible inhibition of the enzyme, and more than 90% activity was lost in three days. The enzyme was not inactivated when ATP was absent or L-aspartic acid β-monohydroxamate was substituted for L-glutamic acid γ-monohydroxamate, suggesting that the inactivation process reflected a mechanism-based reaction of L-glutamic acid γ-monohydroxamate and ATP.