title: Oxygen exchange with water in heme-oxo intermediates during H2O2-driven oxygen incorporation in aromatic hydrocarbons catalyzed by microperoxidase-8.
abstract: The present paper describes the oxygen incorporation into naphthalene and anthracene by H2O2-driven microperoxidase-8, forming alpha-naphthol and anthraquinone, respectively. Microperoxidase-8 is a minienzyme containing a histidinyl-coordinated Fe3+-protoporphyrin IX cofactor covalently attached to an eight-amino-acid peptide. Additional experiments were performed to investigate whether the reaction mechanism involved is like that of peroxidase and/or cytochrome P-450. A reaction pathway like that of cytochrome P-450 implies oxygen transfer to the substrate from the as yet uncharacterized iron-oxo species formed in the reaction of the heine cofactor with H2O2. In contrast, a peroxidase-type reaction chemistry involves reaction pathways proceeding by initial one-electron oxidation of, or H-abstraction from, the substrate, followed by incorporation of oxygen from sources other than the iron-oxo species, i.e. from other than H2O2. The results of the present study exclude Fenton-type chemistry and prove that the minicatalyst is able to catalyze the oxygen incorporation by both peroxidase and cytochrome P-450 types of reaction pathways, while exchange occurs between the high-valency iron-oxo species and H2O. The mechanistic implications of this exchange for cytochrome P-450 are discussed.
authors.affiliation: Department of Biochemistry, Agricultural University, Wageningen, The Netherlands.
authors.forename: V
authors.initials: V
authors.lastname: Dorovska-Taran
authors.forename: M A
authors.initials: MA
authors.lastname: Posthumus
authors.forename: S
authors.initials: S
authors.lastname: Boeren
authors.forename: M G
authors.initials: MG
authors.lastname: Boersma
authors.forename: C J
authors.initials: CJ
authors.lastname: Teunis
authors.forename: I M
authors.initials: IM
authors.lastname: Rietjens
authors.forename: C
authors.initials: C
authors.lastname: Veeger
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000378:metabolism*; D001554:Benzene / Q000378:metabolism*; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism; D006736:Horses; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D008956:Models, Chemical; D009281:Naphthalenes / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D014867:Water
chemical_list: D000873:Anthracenes; D003574:Cytochrome c Group; D009281:Naphthalenes; D014867:Water; C031721:naphthalene; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D010544:Peroxidases; C021799:microperoxidase; D001554:Benzene; D010100:Oxygen