Trypsin-catalyzed oxygen-18 labeling for quantitative proteomics

Abstract

Stable isotope labeling based on relative peptide/protein abundance measurements is commonly applied for quantitative proteomics. Recently, trypsin-catalyzed oxygen-18 labeling has grown in popularity due to its simplicity, cost-effectiveness, and its ability to universally label peptides with high sample recovery. In 18O labeling, both C-terminal carboxyl group atoms of tryptic peptides can be enzymatically exchanged with 18O, thus providing the labeled peptide with a 4 Da mass shift from the 16O-labeled sample. Peptide 18O labeling is ideally suited for generating a labeled "universal" reference sample used for obtaining accurate and reproducible quantitative measurements across large number of samples in quantitative discovery proteomics. © Springer Science+Business Media, LLC 2011.