In Situ Synthesis of Magnetic Mesoporous Phenolic Resin for the Selective Enrichment of Glycopeptides.

Protein glycosylation is a significant participant in a mass of biological processes, which is a pivotal protein post-translational modification. Due to the low contents of glycopeptides compared with nonglycopeptides and the microheterogeneity of glycosylation sites, highly selective enrichment methods for the purification of glycopeptides are required for the comprehensive characterization of glycoproteomics. In this work, a type of magnetic mesoporous phenolic resin (MMP) was prepared using branched polyethylenimine (PEI) as a cross-linker from a homogeneous magnetic Fe3 O4 @SiO2 solution in a resorcinol/formaldehyde monomer aqueous system via an in situ emulsion polymerization procedure. The results showed that MMP exhibited good biocompatibility, a mesoporous structure, nitrogen-containing functionality, excellent hydrophilicity, and solvent resistance by using multiple characterization methods. By taking advantage of the interaction between hydrophilic groups on the MMP and glycan components on the glycopeptides, the acquired MMP was utilized to the selective capture of N-glycopeptides (human IgG or HRP tryptic digests/BSA proteins = 1:50), good recovery yield (70.18-97.23%), superior binding capacity (400 mg g-1 ), and excellent reproducibility. Based on the outstanding performance in standard glycoproteins tryptic digests enrichment, MMP was further used to capture N-glycopeptides from tryptic digests of human serum. A total of 15 unique N-glycopeptides were identified from an ultralow sample volume (0.025 μL) of human serum. Overall, we identified 356 unique N-glycopeptides corresponding to 119 glycoproteins from human serum (0.35 μL) in the overlap of three replicate analyses. All the results have demonstrated that MMP has great potential in large-scale N-glycoproteomics research.