International Journal of Cell Biology / 2012 / Article / Fig 1

Review Article

Established Principles and Emerging Concepts on the Interplay between Mitochondrial Physiology and S-(De)nitrosylation: Implications in Cancer and Neurodegeneration

Figure 1

Mechanisms of S-nitrosylation. Cysteines of low molecular weight (e.g., GSH) and protein sulfhydryls (both termed as RSH) can undergo S-nitrosylation, thus generating S-nitrosothiols (RSNO), by different reactions involving different NO groups and different thiol substrates. RSNO can be formed upon the encountering of with a thiyl radical ( ), with the latter species deriving from an RSH upon metal-catalyzed oxidation or upon homolytic scission of a disulfide bridge ( ) (on the left). However, as is a rare and chemically unstable species, it is plausible to consider that the majority of cellular RSNO generates from the thiolate form of the cysteine (RS) that can result from sulfur deprotonation even at physiological pH. Either as RS, or directly as RSH, cysteine sulfhydryl can undergo nitrosylation by reacting with NO-derived dinitrogen trioxide (N2O3), or directly with nitrosonium ion (NO+) generated upon metal-catalyzed oxidation of . The net transfer of NO+ from an RSNO to an (transnitrosylation) also occurs inside the cells and represents a further reaction to produce S-nitrosylated adducts (on the right).