Chemistry of nitric oxide: biologically relevant aspects

This discussion of NO chemistry has addressed only certain aspects that may be of biological relevance. It is not meant to be a comprehensive in-depth treatment of general NO chemistry. For more information regarding the chemistry of NO and related nitrogen oxides, the reader is referred to a number of reviews (Ragsdale, 1973; Schwartz and White, 1983; Vosper, 1975; McCleverty, 1979; Gilbert and Thomas, 1972; Bonner and Hughes, 1988). Hopefully, it has become evident that an appreciation and knowledge of the chemistry of NO are key to understanding its physiological utility as well as its toxicology. It appears that Nature exploits a variety of the unique chemical aspects of NO in order to attain the needed physiological specificity. For example, the specific activation of guanylate cyclase by NO is most likely due to its unique binding properties to iron hemes. Also, the inherent lack of reactivity of NO makes it a fairly innocuous species unless it is coupled with other radical species, such as O2-. This chemical property thus allows NO to be utilized as a physiological messenger molecule and, under certain conditions, as a cytotoxic effector molecule as well.