S-Nitrosothiols: Chemistry, Biochemistry, and Biological Actions

Abstract

The formation of S-nitrosothiols (RSNOs) species has been clearly demonstrated by the work reviewed in this chapter. These nitric oxide (NO)-bearing species represent one of several possible adducts that can form in biological systems between nitrogen oxide(s) and other biochemical functionalities, including heme iron (to form nitrosylated heme moieties), nonheme iron [to form iron-(di)nitrosyl-(di)thiols], and oxygen-derived species (to form nitrogen dioxide radical with oxygen and peroxynitrite with superoxide). It is recently shown that low-molecular-weight thiols combine with oxides of nitrogen under physiological conditions to form thionitrites or S-nitrosothiols (RSNOs). NO does not react directly with thiols, but must undergo oxidation to form N2O3, a likely candidate nitrosating species in this reaction sequence through its nitrosonium-bearing moiety. RSNOs have a significantly longer chemical half-life than NO, and also possess potent platelet-inhibitory and vasorelaxant properties in vivo that resemble those of endothelium derived relaxing factor (EDRF). The physiological relevance of RSNOs has been confirmed the observation that the predominant form of NO in mammalian plasma is that of an adduct between NO and serum albumin, S-nitrosoalbumin. S-Nitrosoalbumin possesses EDRF-like properties in vivo, including vasorelaxation and platelet inhibition. © 1995, Academic Press, Inc.