Spatially-directed protein identification from tissue sections by top-down LC-MS/MS with electron transfer dissociation

Anal Chem. 2013 Jul 16;85(14):6767-74. doi: 10.1021/ac400832w. Epub 2013 Jul 2.

Abstract

MALDI imaging mass spectrometry (MALDI-IMS) has become a powerful tool for localizing both small molecules and intact proteins in a wide variety of tissue samples in both normal and diseased states. Identification of imaged signals in MALDI-IMS remains a bottleneck in the analysis and limits the interpretation of underlying biology of tissue specimens. In this work, spatially directed tissue microextraction of intact proteins followed by LC-MS/MS with electron transfer dissociation (ETD) was used to identify proteins from specific locations in three tissue types; ocular lens, brain, and kidney. Detection limits were such that a 1 μL extraction volume was sufficient to deliver proteins to the LC-MS/MS instrumentation with sufficient sensitivity to detect 50-100 proteins in a single experiment. Additionally, multiple modified proteins were identified; including truncated lens proteins that would be difficult to assign to an imaged mass using a bottom-up approach. Protein separation and identification are expected to improve with advances in intact protein fractionation/chromatography and advances in interpretation algorithms leading to increased depth of proteome coverage from distinct tissue locations.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cattle
  • Chromatography, Liquid / methods
  • Electrochemical Techniques / methods*
  • Liquid Phase Microextraction / methods*
  • Mass Spectrometry / methods
  • Mice
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods
  • Tandem Mass Spectrometry / methods*
  • Tissue Extracts / analysis*

Substances

  • Tissue Extracts