Absorption spectra of cytochrome P450CAM in the reaction with peroxy acids

Abstract

The reaction of Fe(III) cytochrome P450_CAM with m-chloroperbenzoic acid was studied by rapid scanning absorption spectroscopy. Native low-spin enzyme produced spectra characteristic of two reaction phases that were marked by time intervals with isosbestic positions. The high-spin enzyme substrate complex yielded a series of Soret-region spectra whose properties were dependent on peracid concentration. The simplest model describing the results was a sequence of at least two spectral intermediates, that were not entirely homologous with data measured in reactions with microsomal P450_LM2. Comparisons with related heme protein states indicate higher Fe(IV) oxidation levels provide a plausible interpretation of the P450_CAM spectra.