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

Schey KL, Anderson DM, Rose KL
Anal Chem. 2013 85 (14): 6767-74

PMID: 23718750 · PMCID: PMC3749783 · DOI:10.1021/ac400832w

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.

MeSH Terms (10)

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

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