Evidence for Compound I Formation in the Reaction of Cytochrome-P450cam with m-Chloroperbenzoic Acid

Catalytic Intermediates of Inducible Nitric-oxide Synthase Stabilized by the W188H Mutation*

“…We found that immediately after the initiation of the reaction, a species with a Soret maximum at 421 nm, which we assign to the m-chloroperbenzoic acid-bound ferric species, was observed (data not shown). The spectral properties of the Cmpd I derivative of iNOS oxy are consistent with that of the Cmpd I derivative of P450 identified in the m-chloroperbenzoic acid reaction with the ferric enzyme (37) and in the photo-oxidation reaction of a Cmpd II intermediate (39). It is also similar to the Cmpd I derivative of chloroperoxidase derived from the H 2 O 2 reaction (40).…”

“…We sought to generate the Cmpd I derivative of iNOS oxy by reacting the ferric enzyme with m-chloroperbenzoic acid, which had been widely used to generate ferryl derivatives of hemeproteins (37,38). We found that immediately after the initiation of the reaction, a species with a Soret maximum at 421 nm, which we assign to the m-chloroperbenzoic acid-bound ferric species, was observed (data not shown).…”

X-ray absorption spectroscopic characterization of a cytochrome P450 compound II derivative

“…High valent iron-oxo species in P450 enzymes are extremely shortlived and could not be observed under cryogenic reduction conditions that permitted detection of the immediate precursor to the oxidant(s), a hydroperoxy-iron(III) species (4,5). In fact, no P450 oxidant has been detected under natural conditions, although spectroscopic evidence exists for production of ironoxo species in low conversion under some unnatural conditions (6)(7)(8)(9), and the identities of the P450 oxidants remain in doubt (10,11).…”

Tyrosine Radical Formation in the Reaction of Wild Type and Mutant Cytochrome P450cam with Peroxy Acids

“…Egawa et al (6) performed stopped-flow studies for the reaction of P450cam with m-chloroperbenzoic acid (mCPBA) and found UV-visible spectra similar to cpd I of CPO. Recently, a transient absorption spectrum was observed in stopped-flow studies on CYP119, a cytochrome P450 from the thermophilic bacterium Sulfolobus solfataricus, which reacted with mCPBA (8).…”