NOS oxidizes a guanidine nitrogen of arginine releasing nitric oxide in the form of a free radical and citrulline. Nitric oxide thus generated acts as a messenger in diverse functions including vasodilation neurotransmission, anti-tumor and anti-pathogenic activities. NOS is classified under three types: neuronal NOS (nNOS) or brain NOS (bNOS), induciblr NOS (iNOS) or macrophage NOS (mNOS), and endothelial NOS (eNOS).Synonyms: Constitutive NOS, NC-NOS, NOS type I, Neuronal NOS, Nitric Oxide Synthase, bNOS, nNOS