Global Analysis of Myocardial Peptides Containing Cysteines With Irreversible Sulfinic and Sulfonic Acid Post-Translational Modifications
Jana Paulech, Kiersten A. Liddy, Kasper Engholm-Keller, Melanie Y. White and Stuart J. Cordwell
Molecular & Cellular Proteomics (2015) 14: 609-620.
Cysteine oxidation is an important post-translational modification associated with redox signaling and oxidative stress. While there are a number of methods for the analysis of the reversible cysteine PTM's, the irreversible [-SO2H, -SO3H] modifications are more challenging. Not only is cysteine the second-least abundant amino acid in proteins, but these modifications occupy only 1-2% of these sites under physiological conditions, thus, efficient enrichment is critical.
The authors exploited the unique characteristics of tryptic peptides containing Cys-SO2H/SO3H to generate a novel method based on sequential negative selection by electrostatic repulsion using SCX followed by positive selection by hydrophilic interactions using HILIC. They identified 181 Cys-SO2H/SO3H sites from rat myocardial tissue subjected to physiologically relevant concentrations of H2O2 or to ischemia/re-perfusion injury.