Alkanesulfonate monoxygenase is the monoxygenase of a two-component system that catalyzes the conversion of alkanesulfonates to the corresponding aldehyde and sulfite. Alkanesulfonate monoxygenase (SsuD) has an absolute requirement for reduced flavin mononucleotide (FMNH2), which is provided by the NADPH-dependent FMN oxidoreductase (SsuE).