Bifunctional Magnetic Supramolecular-Organic Framework: A Nanoprobe for Simultaneous Enrichment of Glycosylated and Phosphorylated Peptides

Protein glycosylation and phosphorylation are two important protein post-translational modifications. Mass spectrometry (MS) has been proved to be a powerful technique in comprehensive characterization of protein glycosylation and phosphorylation; however, the complexity of biological matrices and weak ionization efficiency bring a big challenge. Capturing glycopeptides and phosphopeptides from complicated biological samples is indispensable before MS determinations. In this study, a bifunctional gallium ion immobilized magnetic pertriflated pillar[5]arene supramolecular-organic framework (magOTfP5SOF-Ga3+) was designed for the one-step simultaneous enrichment of glycopeptides and phosphopeptides. Thanks to the abundant sulfonic acid groups, the material owns strong hydrophilicity and leads to hydrophilic interaction chromatography for glycopeptides enrichment. Simultaneously, the high loading amount of gallium ion provides immobilized metal ion affinity for phosphopeptides enrichment. The established platform possesses quick magnetic response performance, high sensitivity (detection limits as low as 0.1 fmol and 0.05 fmol for glycopeptides and phosphopeptides, respectively), and good reusability. In addition, the method was applied to the determination of glycopeptides and phosphopeptides in clinical specimens, cell lysates, and mouse liver tissue samples, demonstrating its highly sensitive and specific glycoproteomics and phosphorproteomics analysis in complex biosamples.