Aerobic oxidation of rifamycin SV to rifamycin S catalyzed by horseradish peroxidase.

The aerobic oxidation of rifamycin SV to rifamycin S was catalyzed by horseradish peroxidase. The oxidation rate increased with increasing pH. The oxidation was inhibited by catalase, but superoxide dismutase enhanced the oxidation rate of rifamycin SV. Superoxide inhibited the oxidation and superoxide dismutase relieved the inhibition of oxidation by superoxide. An oxidation mechanism of rifamycin SV catalyzed by horseradish peroxidase which accounts for these data is proposed and a convenient positive assay for superoxide dismutase, using the rifamycin SV-horseradish peroxidase-O2 system, is described.