Abstract
Ionic signal in native MS typically populates high m/z regions of mass spectra, which frequently extend beyond the
precursor ion isolation limits of most commercial mass spectrometers. An approach
explored in this work relies on adding supercharging reagents to protein
solutions as a means of increasing the extent of multiple charging of
non-covalent complexes in ESI MS without compromising their integrity. This
shifts the ionic signal down the m/z
scale to the region where ion selection and isolation can be readily
accomplished, followed by limited charge reduction of the isolated ionic
population. The feasibility of the new approach is demonstrated using
non-covalent complexes formed by hemoglobin with structurally heterogeneous haptoglobin.