Routes for Formation of S-Nitrosothiols in Blood

S-nitrosothiols (RSNO) are involved in post-translational modifications of many proteins analogous to protein phosphorylation. In addition, RSNO have many physiological roles similar to nitric oxide (^•NO), which are presumably involving the release of ^•NO from the RSNO. However, the much longer life span in biological systems for RSNO than ^•NO suggests a dominant role for RSNO in mediating ^•NO bioactivity. RSNO are detected in plasma in low nanomolar levels in healthy human subjects. These RSNO are believed to be redirecting the ^•NO to the vasculature. However, the mechanism for the formation of RSNO in vivo has not been established. We have reviewed the reactions of ^•NO with oxygen, metalloproteins, and free radicals that can lead to the formation of RSNO and have evaluated the potential for each mechanism to provide a source for RSNO in vivo.