title: A new thioether-ligated iron porphyrin as a model of a protonated form of P450 active site.
abstract: Thioether-ligated iron porphyrin (complex 1) was synthesized as a model of the protonated form of P450 to explore the possible involvement of the protonated form in the catalytic cycle, and ether-ligated iron porphyrin (complex 2) was also synthesized for comparison. The thioether and ether ligands enhanced heterolytic O-O bond cleavage of peroxy acid-iron porphyrin complex even in highly hydrophobic media without the assistance of acid or base, using mCPPAA as an oxidant. Competitive oxidation of cyclooctane/cyclooctene catalyzed by iron porphyrins showed that complexes 1 and 2 are less effective than heme thiolate (P450 and a synthetic heme thiolate (SR complex)) in oxidizing alkane. The possibility that thiol-ligated heme, which is a protonated form of heme thiolate, is not involved in the active intermediate structure of P450 is indicated by this result. This is the first report concerning the oxidizing ability of a thioether-ligated iron porphyrin.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Dokoh
authors.forename: N
authors.initials: N
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Higuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Urano
authors.forename: K
authors.initials: K
authors.lastname: Kikuchi
authors.forename: T
authors.initials: T
authors.lastname: Nagano
mesh_terms: D001665:Binding Sites; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000378:metabolism*; D004987:Ethers / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D013440:Sulfides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004987:Ethers; D008024:Ligands; D011166:Porphyrins; D013440:Sulfides; D003577:Cytochrome P-450 Enzyme System