Enzymatic Synthesis of Gamma-glutamylhydroxamic Acid from Glutamic Acid and Hydroxylamine.

The synthesis of y-glutamylhydroxamic acid from glutamine and hydroxylamine is catalyzed by glutamine synthetase in the presence of adenosine diphosphate, inorganic phosphate, and magnesium ions (l), and also by other enzyme preparations (2,3) that do not exhibit a requirement for nucleotides or metal ions. The synthesis of y-glutamylhydroxamic acid from glutamic acid and hydroxylamine that is catalyzed by glutamine synthetase requires both magnesium (or manganese) ions and amounts of ,4TP that are stoichiometric with those of the y-glutamylhydroxamic acid formed. In all these reactions, it appears that hydroxylamine reacts with the enzymatically activated y-carboxy1 group of glutamic acid; this conclusion follows from the important work of Lipmann and Tuttle (4), who first used the formation of hydroxamic acids as an indication and measure of carboxyl group activation. The present communication describes the enzymatic synthesis of y-glutamylhydroxamic acid from glutamic acid and hydroxylamine according to Equation 1.