Properties of cephalosporinase from Proteus morganii.

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Abstract
The cephalosporin .beta.-lactamase (cephalosporinase) was purified from a strain of P. morganii which showed resistance to cephalosporins. The optimal pH was about 8.5 and the optimal temperature was 40.degree. C. The isoelectric point was 8.7 and the MW was estimated to be about 41,000 from sodium dodecyl sulfate-acrylamide gel electrophoresis. The enzyme activity was inhibited by cloxacillin, ampicillin, carbenicillin, cefuroxime, cefotaxime, ceftizoxime (FK749), cefmenoxime (SCE-1365), cefoxitin, cefmetazole, YM09330 and moxalactam (6059-S) but not by calvulanic acid or CP-45899. The .beta.-lactamase also hydrolyzed cephaloridine, cefazolin, cephalothin, cephalexin, cefotiam, cefamandole and benzylpenicillin. These results suggest the possibility that the properties of .beta.-lactamases may be characterized by measuring the kinetic parameters of the enzyme toward newly-introduced .beta.-lactam antibiotics and .beta.-lactamase inhibitors.