Intermediates in the catalytic cycle of methyl coenzyme M reductase: Isotope exchange is consistent with formation of a σ-Alkane-Nickel Complex
The key nickel enzyme for methanogenesis (MCR) catalyzes the formation of CH3D and CH2D2 in a deuterated medium. CH 2D2 is formed by an exchange of deuterium into the S-methyl group of the substrate. Deuterium is incorporated at both carbon atoms of the S-ethyl group of ethyl coenzyme M, and a 13C label is rapidly scrambled within the ethyl group (see scheme). Thus, at least one intermediate is formed and the isotope exchange pattern is consistent with formation of a σ-alkane-nickel complex.
Scheller, Silvan,Goenrich, Meike,Mayr, Stefan,Thauer, Rudolf K.,Jaun, Bernhard