The mechanism of methane and dioxygen activation in the catalytic cycle of methane monooxygenase.
The binuclear structure of the active center of methane monooxygenase plays a determining role in dioxygen activation and in selectivity and specificity of alkane oxidation with this enzyme. A new mechanism is suggested for binding and activation of O2, which involves side-on binding of O2-(2) to iron atoms followed by its conversion to the bis-mu-oxo complex considered as an alternative of ferryl in CH4 activation. This mechanism results in the sequence of the cleavage of the O-O bond of peroxide O/O2-instead of the opposite sequence O2-/O, which takes place in the case of heme monooxygenase cytochrome P-450. Therefore, in this case there is no necessity of the charge relay system [N.B. Gerber and S.G. Sligar, J. Am. Chem. Soc. 114 (1992) 8742] for the transformation of O2 to an active intermediate. The experiment for checking this hypothesis is suggested.
Shteinman
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AA
Institue of Chemical Physics, Chernogolovka, Russian Federation.
D007501:Iron / Q000378:metabolism; D007700:Kinetics; D008697:Methane / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010105:Oxygenases / Q000378:metabolism*
D007501:Iron; D010105:Oxygenases; C021555:methane monooxygenase; D008697:Methane; D010100:Oxygen