NO Synthases
NO synthases utilize L-arginine and molecular oxygen to generate nitric oxide and L-citrulline. eNOS and nNOS are activated by calcium at concentrations > 100 nM whilst iNOS is constitutively active. All three isoforms exist as homodimers and require tetrahydrobiopterin, flavin adenine dinucleotide, flavin mononucleotide and NADPH for catalytic activity. NO synthases have roles in neurotransmission, vasodilation and immune function through the actions of the product nitric oxide.
Nitric Oxide Biosynthesis Pathway
Moncada et al (1997) XIV. International Union of Pharmacology Nomenclature in Nitric Oxide Research. Pharmacol.Rev. 49 137.