A Novel Enrichment Method for Glycopeptides Based on Membrane Ultra-filtration

A novel enrichment method based on an ultra-filtration membrane with a relative molecular mass cutoff value of 3 000 u was developed for the enrichment of glycopeptides and desalting and concentration of the sample in one step.The operating procedure was thus simplified and the sample loss was reduced.Peptide mixtures digested from four standard proteins were used to illustrate the efficiency of this method.The results indicated that one more glycopeptide was detected in the retentate fraction and the relative intensities of all deglycosylated glycopeptides were stronger than those in untreated sample.The method was also applied to human serum sample.The result showed that after ultra-filtering a SCX fraction of the tryptic peptide of the human serum with the membrane,the amount of the identified glycopeptides was 6 times more than those in untreated sample and the enrichment selectivity of glycopeptide was over 85%.This novel glycopeptide enrichment method can provide powerful technical support for the studies of glycoproteomics and glycan related biomarker.