Cryptic stereospecificity of methane monooxygenase
- Univ. of Washington, Seattle, WA (United States); and others
Methane moonooxygenase (MMO, EC 1.14.13.25) catalyzes the NAD(P)H- and O{sub 2}-dependent hydroxylation of methane to methanol. Soluble MMO from the methanotrophic bacterium, Methylosinus trichosporium OB3b, consists of a 245 kDa hydroxylase component containing a {mu}-(R/H)-oxo bridged binuclear iron cluster, a 40 kDa NAD(P)H-dependent oxidoreductase component, and a 15.8 kDa protein, component B, which has no associated cofactors. The hydroxylase component alone can carry out the same oxidations as the reconstituted three-component system when H{sub 2}O{sub 2} is used as the source of oxygen and reducing equivalents. Several mechanisms have been proposed for MMO-catalyzed alkane oxidation; these invoke an intermediate substrate radical, an additional substrate carbocation intermediate, or a concerted oxygen insertion into a substrate carbon-iron bond. Recent studies support the formation of a substrate intermediate not bound to the iron, however, they utilized diagnostic substrates that may not be representative of the natural substrate, methane. The experiments described here address this question more directly by determining the steric course of the oxidation of (S)- or (R)-[1-{sup 2}H{sub 1}, 1-{sup 3}H{sub 1}] ethane to ethanol catalyzed by MMO. 22 refs., 1 fig., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 539443
- Journal Information:
- Journal of the American Chemical Society, Vol. 114, Issue 19; Other Information: PBD: 9 Sep 1992
- Country of Publication:
- United States
- Language:
- English
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