Equal ratio of graphite carbon to activated charcoal for enrichment of N-glycopeptides prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometric identification

Site-specific glycoprofiling of N-glycoproteins is based on the enrichment of glycopeptides. In this study, we develop a simple and economical ZipTip microcolumn packed with a 1:1 ratio of graphite carbon to activated charcoal (w/w) (termed as GA-ZipTip microcolumn) to efficiently isolate and enrich N-glycopeptides from digested mixtures of individual glycoproteins and also investigate the ratio effect on the isolation and enrichment of glycopeptides. The experimental data showed that the microcolumn could efficiently and reproducibly isolate N-glycopeptides from enzymatic mixtures of ovalbumin, fetuin, haptoglobin and human plasma. The results obtained here demonstrate that the GA-ZipTip microcolumn is a powerful tool to enrich unbiasedly N-glycopeptides, which will be benefit for glycoproteomics and complex biological samples. Copyright (C) 2012 John Wiley & Sons, Ltd.