Alkanal monooxygenase are flavin monoxygenases. Molecular oxygen is activated by reaction with reduced flavin mononucleotide (FMNH2) and reacts with an aldehyde to yield the carboxylic acid, oxidized flavin (FMN) and a blue-green light. Bacterial luciferases are heterodimers made of alpha and beta subunits which are homologous. The single activer center is on the alpha subunit. The alpha subunit has a stretch of 30 amino acid residues that is not present in the beta subunit. The beta subunit does not contain the active site and is required for the formation of the fully active heterodimer. The beta subunit does not contribute anything directly to the active site. Its role is probably to stabilize the high quantum yield conformation of the alpha subunit through interactionbs across the subunit interface.
Jiyao W et al.(2023). "The conserved domain database in 2023.",