Preparation of a titanium functionalized polymeric material rich with hydrophilic groups for phosphoproteome and glycoproteome analysis in serum

Abstract

The analysis of protein phosphorylation and glycosylation is critical for investigating disease development. In this work, 1,2-epoxy-5-hexene, N, N-methylenebisacrylamide, was polymerized with vinyl phosphate to produce the polymer (denoted as PVME), which contains a variety of hydrophilic groups. The material's hydrophilicity was further enhanced by a ring-opening reaction with cysteine (the product was denoted as Cys-PVEM). Finally, titanium sulfate was combined with Cys-PVME to form titanium-rich polymers (Cys-PVME-Ti4+) for the enrichment of phosphopeptides and glycopeptides. Cys-PVME-Ti4+ has a good sensitivity (0.02 fmol) and selectivity (1:1000) with a loading capacity of 62 mg/g, recyclability (9 cycles), and a good recovery rate (101.6 ± 0.60%) for phosphopeptides; a good sensitivity (0.01 fmol/μL), selectivity (1:2000), loading capacity of 62.5 mg/g, recyclability (9 cycles), and a good recovery rate (98.7 ± 1.2%) for glycopeptides. In addition, after enrichment with this material, 27 phosphopeptides with 14 phosphoproteins and 223 glycopeptides associated with 88 glycoproteins were captured from the serum of colorectal cancer patients, while 27 phosphopeptides associated with 14 phosphoproteins and 210 glycopeptides associated with 111 glycoproteins were also captured from the serum of a normal control. Gene ontology (GO) analysis revealed that complement activation, extracellular region, extracellular space, blood coagulation, the IgG immunoglobulin complex, and heparin binding were different between normal control and colorectal cancer, implying that related pathways are likely involved in colorectal cancer pathogenesis.