title: Cytochrome P450: the active oxidant and its spectrum.
abstract: This Forum focuses on the nature of the elusive oxidizing intermediate in P450 catalysis. The identity of this species has reemerged as a topic of contentious debate. It was recently reported that laser flash photolysis (LFP) can be used to generate P450 compound I (P450-I) quantitatively. Kinetic analyses of the reaction of the LFP-generated intermediate with substrates have been suggested to indicate that compound I is not the active oxidant in P450 catalysis. We evaluate these claims via an analysis of the UV/visible spectrum of the LFP-generated intermediate. The techniques of singular value decomposition and target testing are used to obtain the spectrum of P450-I in a model-independent manner from stopped-flow data of the reaction of P450 with m-chloroperbenzoic acid. It is shown that the LFP-generated spectrum bears no similarity to the P450-I spectrum. One may conclude that the LFP-generated intermediate is not P450-I.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rittle
authors.forename: Jarod M
authors.initials: JM
authors.lastname: Younker
authors.forename: Michael T
authors.initials: MT
authors.lastname: Green
mesh_terms: D002723:Chlorobenzoates / Q000737:chemistry*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D007700:Kinetics; D016877:Oxidants / Q000737:chemistry*; D010782:Photolysis; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002723:Chlorobenzoates; D016877:Oxidants; D003577:Cytochrome P-450 Enzyme System; C000433:3-chloroperbenzoic acid