Detecting Proteins Glycosylation by a Homogeneous Reaction System with Zwitterionic Gold Nanoclusters

Homogeneous gold nanoclusters (Au NCs) have been widely utilized in drug delivery, chemical sensing, bioassays, and biolabeling due to their unique physical and chemical properties. However, little attention has been paid to their application in detecting protein post-translational modifications. Herein, we describe the development of a homogeneous reaction system with water-soluble zwitterionic Au NCs to capture glycopeptides from complex biological samples. The unique characteristics of Au NCs, such as their molecular-like properties, the excellent homogeneity in aqueous solution, the organic solvent responsive precipitation, and the easy preparation in only 4.5 h, contribute to the high efficiency and high throughput for capturing the targeted glycopeptides. Compared with the conventional heterogeneous system with solid-state adsorbents, the number of characterized glycosylation sites was improved by 35%. Finally, an MS detection limit as low as 50 amol was achieved for the standard glycoprotein (IgG), and 1576 glycosylation sites from 713 glycoproteins were identified from only 60 μg of mouse liver protein. Data are available via ProteomeXchange with identifier PXD005635.