Comparison of gaseous ubiquitin ion structures obtained from a solid and solution matrix using ion mobility spectrometry/mass spectrometry.

Direct comparisons between ESI and the new ionization methods operational directly from surfaces suggest that the protein in its solution structure prior to exposure to the ionization event is either captured (frozen out) at the time of crystallization, or that the protein in the solid matrix is associated with sufficient solvent to maintain the solution structure, or, alternatively, that the observed structures are those related to what occurs in the gas phase with ESI- or MAI-generated ions and not with the solution structures.