Covalent interaction of L-2-amino-4-oxo-5-chloropentanoate at glutamate binding site of gamma-glutamylcysteine synthetase.
gamma-Glutamylcysteine synthetase is inactivated by incubation with low concentrations of L-2-amino-4-oxo-5-chloropentanoate. Very low concentrations of magnesium ions or certain other divalent cations are required for inactivation. L-Glutamate, but not D-glutamate or L-glutamine, protected against inactivation and the protective effect of L-glutamate was increased in the presence of ATP or ADP. L-alpha-Aminobutyrate increased the rate of inactivation by the chloroketone. When the chloroketone was added to the dipeptide synthesis system, inhibition was competitive with L-glutamate. Iodoacetamide also inhibited the enzyme; however, this reagent is much less effective than the chloroketone and inhibition by iodoacetamide is less effectively prevented by L-glutamate. Studies with 14C-labeled chloroketone showed that this reagent binds stoichiometrically to the enzyme, and that it binds exclusively to its heavy subunit.
D000596:Amino Acids; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002413:Cations, Divalent; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D005971:Glutamates; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008297:Male; D010421:Pentanoic Acids; D010453:Peptide Synthases / Q000378:metabolism; D051381:Rats; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D000596:Amino Acids; D002413:Cations, Divalent; D005971:Glutamates; D010421:Pentanoic Acids; D010453:Peptide Synthases; D005721:Glutamate-Cysteine Ligase