Highly Selective Enrichment of Sialylated Glycopeptides Using Titania Sol-Gels for MALDI-MSApplications

摘要

A novel titania sol-gel was developed for highly selective enrichment of the sialylated glycopeptides in mass spectrometry based glycoproteomics applications. Titania sol-gel was synthesized following easy and cheap pathway and an enrichment method was developed on the basis of specific interactions between the sol-gel and sialylated glycans. The site-specific enrichment method was developed on the basis of interaction between lewis acid and base pairs such as the titanium centers on the sol-gel and sialic acids on glycans. MALDI-MS data showed that the sialylated glycopeptides in a complex peptide mixture of human transferrin digest were effectively captured by the titania sol-gels. The sol-gels were washed with the buffer solutions which increase polarity and pH of the medium to substantially remove the non-glycopeptides. The addition of 1.0 M glycolic acid into the loading buffer dramatically improved the selectivity of titania sol-gels for the glycopeptides. Sialylated glycopeptides were successfully eluted using the buffer solution at alkaline (pH≈9-10) conditions. The specific losses representing 162 Da Hexose (Hex), 203 Da N-Acetyl Hexose (HexNAc) and 291 Da N-Acetylneuraminic Acid (NeuNAc) were observed in MALDI mass spectra using 2,5-dihydroxybenzoic acid matrix due to prompt fragmentation of the glycans.