Capture and identification of carbohydrate-binding proteins by SPR and CREDEX-MS

Abstract

Carbohydrate-binding proteins of non-immunological origin -lectins- have been recognized over the last decades as decisive players in numerous biological processes, ranging from cellcell communication, fertilization, pathogen-cell adhesion to metastasis. Consequently, there is an increasing interest in finding powerful and nanosized tools to screen for these molecules and to study their carbohydrate interactions in detail. Here, two complementary approaches are described to characterize lectin-carbohydrate interactions with high sensitivity, low sample consumption, and without the need for sample labelling: SPR and CREDEX-MS. In SPR, we have developed an approach where the sugar is immobilized onto a sensor surface through a tailor-made peptide module that allows (1) to capture the lectin, (2) to characterize the interaction through kinetic and thermodynamic parameters, and (3) to identify the interacted protein by mass spectrometry. In CREDEX-MS, based on proteolytic excision of proteincarbohydrate complexes and mass spectrometric analysis, the peptides comforming the carbohydrate binding domain are identified.