Open AccessOxygen exchange with water in heme‐oxo intermediates during H 2 O 2 ‐driven oxygen incorporation in aromatic hydrocarbons catalyzed by microperoxidase‐8
Author(s) -
DorovskaTaran Victoria,
Posthumus Maarten A.,
Boeren Sjef,
Boersma Marelle G.,
Teunis Cees J.,
Rietjens Ivonne M. C. M.,
Veeger Cees
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2530659.x
Subject(s) - chemistry , catalysis , heme , cytochrome c , cytochrome , substrate (aquarium) , oxygen , anthracene , peroxidase , photochemistry , stereochemistry , organic chemistry , enzyme , biochemistry , oceanography , mitochondrion , geology
The present paper describes the oxygen incorporation into naphthalene and anthracene by H 2 O 2 ‐driven microperoxidase‐8, forming α‐naphthol and anthraquinone, respectively. Microperoxidase‐8 is a minienzyme containing a histidinyl‐coordinated Fe 3+ ‐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 heme cofactor with H 2 O 2 . 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 H 2 O 2 . 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 H 2 O. The mechanistic implications of this exchange for cytochrome P ‐450 are discussed.