F430 is the cofactor (sometimes called the coenzyme) of the enzyme methyl coenzyme M reductase (MCR).MCR catalyzes the reaction EC 2.8.4.1 that releases methane in the final step of methanogenesis: CH3–S–CoM + HS–CoB → CH4 + CoB–S–S–CoM It is found only in methanogenic Archaea and anaerobic methanotrophic Archaea. It occurs in relatively high concentrations in archaea that are involved in reverse methanogenesis: these can contain up to 7% by weight of the nickel protein.