Quantitative analysis of redox-sensitive proteome with DIGE and ICAT

Oxidative modifications of protein thiols are important mechanisms for regulating protein functions. The present study aimed to compare the relative effectiveness of two thiol-specific quantitative proteomic techniques, difference gel electrophoresis (DIGE) and isotope coded affinity tag (ICAT), for the discovery of redox-sensitive proteins in heart tissues. We found that these two methods were largely complementary; each could be used to reveal a set of unique redox-sensitive proteins. Some of these proteins are low-abundant signaling proteins and membrane proteins. From DIGE analysis, we found that both NF-κ:B-repressing protein and epoxide hydrolase were sensitive to H ₂O ₂ oxidation. In ICAT analysis, we found that specific cysteines within sacroplasmic endoplamic reticulum calcium ATPase 2 and voltage-dependent anion-selective channel protein 1 were sensitive to H ₂O ₂ oxidation. From these analyses, we conclude that both methods should be employed for proteome-wide studies, to maximize the possibility of identifying proteins containing redox-sensitive cysteinyl thiols in complex biological systems.