Interaction between monobactams and Streptomyces R61 DD-carboxypeptidase

The monobactams are a novel family of monocyclic beta-lactam antibiotics characterized by the 2-oxoazetidine-1-sulfonic acid moiety. A series of monobactams bind covalently to the Streptomyces R61 DD-carboxypeptidase in a manner similar to that for bicyclic beta-lactams, especially cephalosporins. The similarity of interaction was established by the following criteria: inhibition of binding by diisopropylfluorophosphate and alpha-dicarbonyls; stoichiometry of binding; similarity of partial proteolysis products of radiolabelled enzyme; rates of release of bound beta-lactams; nature of hydrolysis and hydroxylaminolysis products.