Surface-based and mass spectrometric approaches to deciphering sugar-protein interactions in a galactose-specific agglutinin

Abstract

Over the last decades, sugar-protein interactions have been acknowledged as key players in numerous biological recognition processes, such as those occurring during pathogen-host adhesion or fertilization. Consequently, interest in finding powerful and nanosized tools to study glycan-protein interactions in detail has increased significantly in recent years. Here, two complementary approaches are applied to characterize glycan-protein interactions with high sensitivity, low sample consumption, and without the need for sample labelling: surface plasmon resonance (SPR) and an approach that combines limited proteolysis and mass spectrometry. Combination of these two approaches to investigate glycan-protein interactions allows (1) to characterize interactions through kinetic and thermodynamic parameters, (2) to capture efficiently the carbohydrate-binding protein, and (3) to identify the interacted protein and its carbohydrate binding site by mass spectrometry. As a proof of principle, the interaction of the galactosespecific legume lectin Erythrina cristagalli agglutinin with several sugars has been characterized indepth by means of these two approaches.