FURTHER EVIDENCE FOR MULTIPLE PATHWAYS IN SOLUBLE METHANE-MONOOXYGENASE-CATALYZED OXIDATIONS FROM THE MEASUREMENT OF DEUTERIUM KINETIC ISOTOPE EFFECTS
UNSPECIFIED. (1994) FURTHER EVIDENCE FOR MULTIPLE PATHWAYS IN SOLUBLE METHANE-MONOOXYGENASE-CATALYZED OXIDATIONS FROM THE MEASUREMENT OF DEUTERIUM KINETIC ISOTOPE EFFECTS. EUROPEAN JOURNAL OF BIOCHEMISTRY, 226 (2). pp. 555-560. ISSN 0014-2956Full text not available from this repository.
The data from the deuterium isotope experiments in this study show that the primary kinetic isotope effect for methane oxidation catalysed by soluble methane monooxygenase from Methylococcus capsulatus (Bath) is very small, <2. In contrast, the primary kinetic isotope effect for -CH3 group oxidation in toluene is large, >7. A mechanistic pathway in which a substrate radical is formed from hydrogen atom abstraction by a ferryl species is believed to operate for CH4, the toluene -CH3 group and similar alkanes. Direct oxygen atom addition, rather than H atom abstract- tion, is indicated for aromatic ring oxidations in benzene and toluene and for styrene oxide formation from styrene. Thus, more than one mechanistic pathway appears to operate in soluble methane-monooxygenase-catalysed reactions and, in some cases, the pathway chosen may be dictated by the substrate.
In the soluble methane-monooxygenase-catalysed oxidation of toluene the rates of: (a) substrate dissociation from the enzyme-substrate complex, (b) product formation and (c) product release (benzyl alcohol and p-cresol) from the enzyme-product complex are comparable in magnitude. Therefore all three of these steps are partially rate-determining in the soluble methane monooxygenase catalytic cycle for toluene oxidation.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||EUROPEAN JOURNAL OF BIOCHEMISTRY|
|Official Date:||1 December 1994|
|Number of Pages:||6|
|Page Range:||pp. 555-560|
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