Oxygen exchange with water in heme‐oxo intermediates during H2O2‐driven oxygen incorporation in aromatic hydrocarbons catalyzed by microperoxidase‐8
The present paper describes the oxygen incorporation into naphthalene and anthracene by H2O2‐driven microperoxidase‐8, forming α‐naphthol and anthraquinone, respectively. Microperoxidase‐8 is a minienzyme containing a histidinyl‐coordinated Fe3+‐protoporphyrin IX cofactor covalently attached to an e...
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Veröffentlicht in: | European journal of biochemistry 1998-05, Vol.253 (3), p.659-668 |
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Sprache: | eng |
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Zusammenfassung: | The present paper describes the oxygen incorporation into naphthalene and anthracene by H2O2‐driven microperoxidase‐8, forming α‐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 heme cofactor with H2O2. In contrast, a peroxidase‐type reaction chemistry involves reaction pathways proceeding by initial one‐electron oxidation of, or H‐ion 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. |
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ISSN: | 0014-2956 1432-1033 |
DOI: | 10.1046/j.1432-1327.1998.2530659.x |