Endothelial nitric-oxygen synthase endothelium

Endothelial nitric oxide synthase (eNOS). The enzyme responsible for nitric oxide production in human endothelium. Nitric oxide (NO) is a gas that relaxes vascular smooth muscle cells, induces vasodilatation and is critical for global vascular homeostasis. cNOS is a homodimer enzyme that couples oxygen consumption to L-arginine use to produce NO. In its uncoupled form, cNOS is rendered into a source of superoxides instead of NO. 

ABSTRACT In mammals, nitric oxide (NO) is a reactive free radical involved in diverse physiological functions. NO and its redox-related forms NO+ and NO react with di(oxygen) and its derivatives, with metalloproteins and thiol-containing proteins. NO-mediated nitrosation of proteins represents an important cellular regulatory mechanism. Biosynthesis of NO is catalysed by nitric oxide synthase (NOS). Three isoenzymes representing distinct gene products have been identified the inducible NOS isoform, the constitutive neuronal and endothelial isoforms. Inducible and constitutive NOSs have the same structural features, but their activities differ in their dependence to calcium and the rate of NO produced. The principal NO-mediated functions in mammals are endothelium-dependent relaxation, neurotransmission and immune response. The role of NO in the antitumor immune response comprises both regulatory and effector functions at the intra- or inter-cellular level. The first function includes inhibition of lymphocyte proliferation or participation in different transduction pathways. The second fiinction includes pro- or anti-tumoral effects and NO-mediated cell toxicity or cell resistance to apoptosis. 

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