Detergent Release Prolongs the Lifetime of Native-like Membrane Protein Conformations in the Gas-Phase

Recent studies have suggested that detergents can protect the structure of membrane proteins during their transition from solution to the gas-phase. Here we provide mechanistic insights into this process by interrogating the structures of membrane protein-detergent assemblies in the gas-phase using ion mobility mass spectrometry. We show a clear correlation between the population of native-like protein conformations and the degree of detergent attachment to the protein in the gas-phase. Interrogation of these protein-detergent assemblies, by tandem mass spectrometry, enables us to define the mechanism by which detergents preserve native-like protein conformations in a solvent free environment. We show that the release of detergent is more central to the survival of these conformations than the physical presence of detergent bound to the protein. We propose that detergent release competes with structural collapse for the internal energy of the ion and permits the observation of transient native-like membrane protein conformations that are otherwise lost to structural rearrangement in the gas-phase.