Enzymatic Conversion of 5-Oxo-L-Proline (L-Pyrrolidone Carboxylate) to L-Glutamate Coupled with Cleavage of Adenosine Triphosphate to Adenosine Diphosphate a Reaction in the γ-Glutamyl Cycle

摘要

A new enzyme, 5-oxoprolinase, was found in rat kidney and in several other tissues; it catalyzes the conversion of 5-oxo-L-proline (L-5-oxo-pyrrolidine-2-carboxylic acid, L-2-pyrrolidone-5-carboxylic acid, L-pyroglutamic acid) to L-glutamic acid, with concomitant stoichiometric cleavage of ATP to ADP and orthophosphate. The reaction catalyzed by 5-oxoprolinase, in which 5-oxoproline formed from γ-glutamyl amino acids by the action of γ-glutamylcyclotransferase is converted to glutamate, appears to function in the γ-glutamyl cycle. 5-Oxoprolinase requires Mg⁺⁺ (or Mn⁺⁺) and K⁺ (or NH4⁺) for activity. The equilibrium is markedly in favor of glutamate formation at pH 7.8.