Electron transfer with no dissociation ion mobility–mass spectrometry (ETnoD IM-MS). The effect of charge reduction on protein conformation

•Electron transfer to proteins is reported as a novel method to probe changes in protein structure termed ETnoD.•A single electron is shown to cause dramatic structural rearrangement.•Smaller conformers preferentially reduce, leaving more extended exposed precursors.•A given arrival time distribution is preferred for a protein with a given net charge indicating charge dictates structure in the gas phase.•Improvement in mobility resolution is observed following exposure to the 1,3-dicyanobenzene reagent which is cautiously attributed to anion cation cooling.•A model is proposed where the transferred electron lessens the contribution of stabilising salt bridges to the gas phase protein structure.