Label-Free Discovery Array Platform for the Characterization of Gly-can Binding Proteins and Glycoproteins

The identification of carbohydrate-protein interactions is central to our understanding of the roles of cell-surface carbohydrates (the glycocalyx), fundamental for cell-recognition events. Therefore there is a need for fast high-throughput biochemical tools to capture the complexity of these biological interactions. Here we describe a rapid method for qualitative label-free detection of carbohydrate-protein interactions on arrays of simple synthetic glycans, more com-plex natural glycosaminoglycans (GAG) and lectins/carbohydrate binding proteins using MALDI-ToF mass spectrometry. The platform can unequivocally identify proteins that are captured from either purified or complex sample mixtures, in-cluding biofluids. Identification of proteins bound to the functionalized array is achieved by analyzing either the intact protein mass, or, after on-chip proteolytic digestion, the peptide mass fingerprint and/or tandem mass spectrometry of selected peptides, which can yield highly diagnostic sequence information. The platform described here should be a valu-able addition to the limited analytical toolbox that is currently available for glycomics.