An effective and in-situ method based tresyl-functionalized porous polymer material for enrichment and digestion of membrane proteins and its application in extraction tips

Membrane proteins are one of promising targets for drug discovery because of the unique properties in physiological processes. Due to their low abundance and extremely hydrophobic nature, the analysis of membrane proteins is still a great challenge. In this work, an effective and in-situ method were developed to enrich and digest membrane proteins by adopting tresyl-functionalized porous polymer material. With tresyl groups, the material can effectively immobilize membrane proteins via covalent bonding on the surface. The material became a facile carrier to enrich membrane proteins from the rat liver in detergents and organic solvents owing to its outstanding binding capacity and excellent biocompatibility. Moreover, it was further applied in extraction tips to capture and in-situ digest the pretreatment membrane proteins in two different solutions. A total of 600 membrane proteins (51% of total protein groups) and 359 transmembrane proteins were identified by nano-LC-ESI-MS/MS in 4% sodium dodecyl sulfate (SDS), and similar results were achieved in the 60% methanol solution. All these results demonstrated that the new approach is of great promise for large-scale characterization of membrane proteins.