PURIFICATION AND PROPERTIES OF A CHROMOSOMAL BETA-LACTAMASE FROM KLEBSIELLA-OXYTOCA

A beta-lactamase was purified from Klebsiella oxytoca strain GN10650. The enzyme was chromosomally-mediated and gave a single protein band on polyacrylamide gel electrophoresis. Its pI was 5.34 and its MW was approximately 27,000. The optimal pH and temperature were about 7.0 and 50-degrees-C, respectively. The specific activity of the enzyme was 1,207 units per mg of protein for hydrolysis of penicillins and cephalosporins, including cefuroxime, cefotaxime, and aztreonam. The enzyme activity was inhibited by p-chloromercuribenzoate, iodine, ferrous ion, and by clavulanic acid. Rabbit antibodies raised against the purified K. oxytoca enzyme showed no cross-reactivity in neutralization tests with beta-lactamases produced by other species of Gram-negative bacteria.