Improvement in the resting-cell bioconversion of penicillin G to deacetoxycephalosporin G by addition of catalase

Aims: To improve the resting cell bioconversion of penicillin G to deacetoxycephalosporin G (DAOG) by elimination of an oxidizing intermediate which inactivates the enzyme during the reaction. Methods and Results: Resting cells of Streptomyces clavuligerus strain NP1 were incubated with penicillin G, required co-factors and decane in the presence of catalase or superoxide dismutase, and production of DAOG was measured. Catalase stimulated the bioconversion but superoxide dismutase did not. Conclusions: Production of hydrogen peroxide during the ring expansion reaction is at least partially responsible for enzyme inactivation. Significance and Impact of the Stud,: Catalase addition improves the bioconversion and will contribute to the eventual replacement of the current multi-step, expensive and environmentally-unfriendly chemical ring expansion by a biological route.