A CLASS-A BETA-LACTAMASE FROM PSEUDOMONAS-STUTZERI THAT IS HIGHLY-ACTIVE AGAINST MONOBACTAMS AND CEFOTAXIME

A beta-lactamase produced by Pseudomonas stutzeri was purified to prot ein homogeneity, and its physicochemical and catalytic properties were determined. Its profile was unusual since, in addition to penicillins , the enzyme hydrolysed second- and third-generation 'beta-lactamase-s table' cephalosporins and monobactams with similar efficiencies. On th e basis of the characteristics of the interaction with beta-iodopenici llanic acid, the enzyme could be classified as a class-A beta-lactamas e. However, when compared with most class-A beta-lactamases, it exhibi ted significantly lower k(cat.)/K(m) values for the compounds usually considered to be the best substrates of these enzymes.