Mechanism of cytochrome c peroxidase. O-benzoylhydroxylamine as an analog of hydrogen peroxide.

A number of reagents, some of which are electronic analogs of hydrogen peroxide, will replace it in the reactions of cytochrome c peroxidase. These compounds include N-bromosuccinimide, sodium hypochlorite, and the novel oxidizing agent O-benzoylhydroxylamine. If fragments of the oxidant played a functional role in the structure of the oxidized form of the enzyme, it would be expected that the product formed from O-benzoylhydroxylamine would differ from that formed from hydrogen peroxide. The products formed on reaction of the two oxidizing agents with cytochrome c peroxidase are indistinguishable. This results carries implications for the structure of the so-called ES compound. The extension in the range of specific substrates for cytochrome c peroxidase allows identification of the structure which compounds must possess to be oxidizing substrates for the enzyme. A mechanism for the first step of the reaction is suggested. O-Benzoylhydroxylamine is also a reducing agent, and its reaction with the enzyme is analogous to that of hydrogen peroxide with catalase. The final product of the reaction is the inert nitric oxide complex of ferrous cytochrome c peroxidase.