Biochemical Properties of a Cephalosporin β-Lactamase from Pseudomonas aeruginosa

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The cephalosporin β-lactamase from Pseudomonas aeruginosa GN918 was purified using CM-Sepha-dex column chromatography. The resulting preparation gave a single protein peak on electro-focusing column chromatography and a single protein band on polyacrylamide-gel electrophoresis. The specific enzyme activity was 22950 units per mg of the purified enzyme protein. The optimal pH was 7.5 and the optimal temperature was 40C for the hydrolysis of cephaloridine. Isoelectric point was 8.7 and the approximate molecular weight of the enzyme was found to be 34000±2000. The enzyme activity was inhibited by iodine, p-chloromercuribenzoate and semi-synthetic penicillins. The enzymological properties of the isolated preparation have been compared with β-lactamases derived from other gram-negative enteric bacteria.