the key structural features that are involved in the substrate and active site interaction are highly conserved, e.g. residues Pro214, Glu235, Trp234, Tyr237, Asn246, and Gln129, substrate binding structure and mechanism, overview
reaction mechanism, NO release and transport, overview, NO formation through sequential electron transfer and the oxidation of L-arginine, in the catalytic process, FMN, FAD, and tetrahydrobiopterin are required as coenzymes, and the presence of Ca2+/calmodulin can aid the electron transfer, isozymes NOS1 and NOS3 perform a similar reaction mechanism
Binds FAD, FMN, heme (iron protoporphyrin IX) and tetrahydrobiopterin. This eukaryotic enzyme, which is found in plants  and animals [1-3], consists of oxygenase and reductase domains that are linked via a regulatory calmodulin-binding domain. Upon calcium-induced calmodulin binding, the reductase and oxygenase domains form a complex, allowing electrons to flow from NADPH via FAD and FMN to the active center. May produce superoxide under certain conditions . cf. EC 22.214.171.124, nitric-oxide synthase [NAD(P)H dependent].