Book excerpt: This thesis describes the development and application of electrospray ionization mass spectrometry (ESI-MS) based techniques to investigate protein-carbohydrate interactions in vitro. A catch-and-release electrospray ionization mass spectrometry (CaR-ESI-MS) assay was developed for the identification of specific interactions between water-soluble multisubunit proteins and glycosphingolipids (GSL). The assay is of high sensitivity and specificity, and demonstrates the potential for discovering biologically relevant protein-GSL interactions. Collision-induced dissociation (CID) experiments and molecular dynamic simulations were performed to investigate the dissociation pathways of multisubunit protein-ligand complexes in the gas phase. The observation of multiple dissociation pathways suggests that collisional activation of multisubunit protein-ligand complexes in the gas phase is likely to induce significant changes to the nature of the protein-ligand interactions.