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

Abstract

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).

Integrating ion mobility and imaging mass spectrometry for comprehensive analysis of biological tissues: A brief review and perspective

“…60,74,75 For example, TWIMS has been coupled to many ion sources including MALDI, 36,[76][77][78][79][80] DESI, 60,74,80,81 LAESI, 82,83 and LESA (Figure 2A-D). 48,61,84,85 is a point of much discussion in the scientific community. [85][86][87] In another example, Hale and colleagues showed that mobility information provided by TWIMS enabled filtering of spectral noise that contributed to improved ion image quality.…”

“…[85][86][87] In another example, Hale and colleagues showed that mobility information provided by TWIMS enabled filtering of spectral noise that contributed to improved ion image quality. 61 For example, the authors…”

“…to-noise (S/N). 36,60,61 As the resolving power of ion mobility technologies continues to improve, applications of ion mobility-IMS to discriminate biomolecules closer in m/z without the need for ultra-high mass resolving power mass spectrometers will be of significant benefit. In this article, we briefly describe recent advances in the field of ion mobility-IMS.…”

“…While secondary ion mass spectrometry (SIMS) is also a prevalent IMS ion source, 56,57 it has not yet been coupled to ion mobility and will therefore not be covered in this perspective. Regardless of IMS ion source, ion mobility provides efficient ion separation prior to mass analysis 59 and increased signal‐to‐noise (S/N) 36,60,61 . As the resolving power of ion mobility technologies continues to improve, applications of ion mobility‐IMS to discriminate biomolecules closer in m / z without the need for ultra‐high mass resolving power mass spectrometers will be of significant benefit.…”

Mass Spectrometry Analysis of Intact Proteins from Crude Samples

“…(Right) Mass spectrum of an intact hemoglobin heterotetramer (+16) and heterodimer (+11) sampled directly from the tissue section labeled by a red square in the left panel, which marks the position of the renal pelvis, which is rich in blood vessels. Adapted with permission from ref ( 71 ). Copyright (2020) American Chemical Society.…”