Enzymatic studies on the mechanism of action of cefoxitin. Correlation between the affinities of cefoxitin to penicillin-binding proteins and its rates of inhibition of the respective penicillin-sensitive reactions in E. coli.

The affinities of cefoxitin, a cephamycin antibiotic, to penicillin-binding proteins of Escherichia coli were reexamined using a recently developed method for separating penicillin-binding proteins. The inhibitions by this antibiotic of four measurable penicillin-sensitive enzymatic reactions, the reactions of D-alanine carboxypeptidases IA and IB, cross-bridge formation and concomitant release of D-alanine, were also measured. An approximate correlation was found between the affinities of cefoxitin to the penicillin-binding proteins responsible for these reactions and its rates of inhibition of the respective penicillin-sensitive reactions.