Description
Nitric Oxide (NO) is synthesized in biological systems by the enzyme Nitric Oxide Synthase (NOS). NOS is a remarkably complex enzyme which acts on molecular oxygen, arginine, and NADPH to produce NO, citrulline, and NADP+. This process requires five additional cofactors (FMN, FAD, Heme, calmodulin, and tetrahydrobiopterin) and two divalent cations (calcium and heme iron). Three distinct isoforms of NOS have been identified