Abstract
A strain of Fusobacterium nucleatum which produced high levels of beta-lactamase was isolated. The specific activity of the unpurified beta-lactamase was 7.8 U/mg of protein. By Sephacryl S-300 and S-200 column passage and chromatofocusing, the enzyme was purified 450-fold. Sodium dodecyl sulfate-gradient gel electrophoresis revealed a single band. The enzyme hydrolyzed phenoxymethylpenicillin, benzylpenicillin, and ampicillin more rapidly than carbenicillin and piperacillin. Cephaloridine, cefaclor, cephalothin, imipenem, and SCH 34343 had hydrolysis rates of less than or equal to 1% that of phenoxymethylpenicillin. The enzyme was inhibited by clavulanic acid and RO-15-1903/001 but not by p-mercuribenzoate or cefoxitin. Molecular weight by gel filtration was determined to be 21,000 and by sodium dodecyl sulfate-gradient gel electrophoresis was determined to be 26,000. The amino acids aspartic acid-asparagine, glutamic acid-glutamine, serine, glycine, and lysine dominated the amino acid composition.