Nitric oxide synthase (NOS) catalyzes the oxidation of arginine to nitric oxide (NO) and citrulline. Three distinct isoforms of NOS have been described having nomenclature based on the tissue source from which they were originally cloned. These three isoforms are neuronal/brain NOS (nNOS/bNOS/NOS-I), inducible NOS (iNOS/NOS-II), and endothelial NOS (eNOS/NOS-III).1,2 nNOS is a soluble enzyme found in brain, the peripheral nervous system and skeletal muscle.3,4 An alternately spliced form of nNOS (nNOSμ) containing a 34 amino acid insert has been identified in skeletal muscle.5 In neurons, protein-protein interactions with PSD95 and PSD93 via the PZD domain at the N-terminus of nNOS localizes the enzyme with NMDA receptors.6,7 Although nNOS was originally thought to be constitutively expressed, abundant evidence suggests expression is regulated by a variety of conditions.8WARNING This product is not for human or veterinary use.
