Native LESA TWIMS-MSI: Spatial, Conformational, and Mass Analysis of Proteins and Protein Complexes

We
have previously demonstrated native liquid extraction surface
analysis (LESA) mass spectrometry imaging of small intact proteins
in thin tissue sections. We also showed calculation of collision cross
sections for specific proteins extracted from discrete locations in
tissue by LESA traveling wave ion mobility spectrometry (TWIMS). Here,
we demonstrate an integrated native LESA TWIMS mass spectrometry imaging
(MSI) workflow, in which ion mobility separation is central to the
imaging experiment and which provides spatial, conformational, and
mass information on endogenous proteins in a single experiment. The
approach was applied to MSI of a thin tissue section of mouse kidney.
The results show that the benefits of integration of TWIMS include
improved specificity of the ion images and the capacity to calculate
collision cross sections for any protein or protein complex detected
in any pixel (without a priori knowledge of the presence
of the protein).