Redox properties of methane monooxygenase hydroxylase and regulation by component B
- Carnegie-Mellon Univ., Pittsburgh, PA (United States)
Methane Monooxygenase is a three protein component enzyme system which catalyzes the oxidation of methane to methanol in the methanotrophic bacterium, Methylosinus trichosporium OB3b. The three protein components include a reductase containing one FAD and one [2Fe-2S] cluster, a hydroxylase containing two {mu}-oxo-bridged dinuclear iron clusters and a component B with no redox centers. Substrate oxidation occurs at the {mu}-oxo-bridged dinuclear iron clusters of the hydroxlase component. Preliminary results from EPR-spectroelectrochemical titration indicate that the redox potentials for this center are E{sub 1}=+76 mV and E{sub 2}=21 mV (pH 7.0 and 4{degrees}C). This potential separation represents a maximum of 61% intermediate or mixed valent species formed during titration. The maximum amount of mixed valent species formed during titration has been confirmed by quantitation using Mossbauer spectroscopy of samples acquired from an EPR-spectrochemical titration of the hydroxylase component enriched in {sup 57}Fe. Binding of component B causes the overall midpoint potential to shift {approximately} 120 mV more negative, indicating that this component may be important in redox potential during catalysis.
- OSTI ID:
- 141114
- Report Number(s):
- CONF-930304--
- Country of Publication:
- United States
- Language:
- English
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