Produces nitric oxide (NO) which is a messenger molecule with diverse functions throughout the body. H(+) + 2 L-arginine + 3 NADPH + 4 O2 = 4 H2O + 2 L-citrulline + 3 NADP(+) + 2 nitric oxide Binds 1 FAD. Binds 1 FMN. Belongs to the NOS family.