Methane monooxygenase (MMO) reductase of methanotrophs catalyzes the NADH-dependent hydroxylation of methane to methanol. This multicomponent enzyme mediates electron transfer via a hydroxylase (MMOH), a coupling protein, and a reductase which is comprised of an N-terminal [2Fe-2S] ferredoxin domain, an FAD binding subdomain, and an NADH binding subdomain. Oxygenases oxidize hydrocarbons using dioxygen as the oxidant. Dioxygenases add both atom of oxygen to the substrate, while mono-oxygenases add one atom to the substrate and one atom to water.
Jiyao W et al.(2023). "The conserved domain database in 2023.",