title: Protective effects of dimethyl sulfoxide on labile protein interactions during electrospray ionization.
abstract: Electrospray ionization mass spectrometry is a valuable tool to probe noncovalent interactions. However, the integrity of the interactions in the gas-phase is heavily influenced by the ionization process. Investigating oligomerization and ligand binding of transthyretin (TTR) and the chaperone domain from prosurfactant protein C, we found that dimethyl sulfoxide (DMSO) can improve the stability of the noncovalent interactions during the electrospray process, both regarding ligand binding and the protein quaternary structure. Low amounts of DMSO can reduce in-source dissociation of native protein oligomers and their interactions with hydrophobic ligands, even under destabilizing conditions. We interpret the effects of DMSO as being derived from its enrichment in the electrospray droplets during evaporation. Protection of labile interactions can arise from the decrease in ion charges to reduce the contributions from Coulomb repulsions, as well as from the cooling effect of adduct dissociation. The protective effects of DMSO on labile protein interactions are an important property given its widespread use in protein analysis by electrospray ionization mass spectrometry (ESI-MS).
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institutet , Stockholm, S-171 77, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Landreh
authors.forename: Gunvor
authors.initials: G
authors.lastname: Alvelius
authors.forename: Jan
authors.initials: J
authors.lastname: Johansson
authors.forename: Hans
authors.initials: H
authors.lastname: Jörnvall
mesh_terms: D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D011506:Proteins; D004121:Dimethyl Sulfoxide