Ion Mobility Separations of Protein Conformers with Resolving Power up to 400 Using Hydrogen-Rich Gas Buffers

摘要

H_2/N_2 buffers with up to 85% H_2 increase FAIMS resolving power for protein conformers fivefold, up to 400. Slower diffusion for large ions permits extended separations even at 85% H_2. Over 10 conformers were fully resolved for some charge states of ubiquitin. Peak widths equal to or narrower than those for smaller ions under same conditions, scale as a function of separation time and protein charge as prescribed for instrumental (diffusional) broadening. Results indicate that individual protein geometries rather than conformer ensembles were largely distinguished. Initial work shows that the capability extends to larger proteins.