一氧化氮合酶（NOS）是NO生成唯一的限速酶，分为神经型NOS（nNOS）、内皮型NOS（eNOS）和诱导型NOS（iNOS）3型。NOS以左旋精氨酸和分子氧为底物，还原型尼克酰胺腺瞟吟二核苷酸磷酸脱氢酶（NADPH－diaphorase，NADPH-d）提供电子，经氧化脱氨基产生NO和左旋瓜氨酸[1]。NOS和N Nitric oxide synthase (NOS) is the only rate-limiting enzyme for NO production and is classified into neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS) type 3. NOS takes L-arginine and molecular oxygen as substrates, and the reduced NADPH-diaphorase (NADPH-d) provides electrons, which are oxidized and deaminated to produce NO and Ligu ACN Acid [1]. NOS and N