Optimization of Urea Based Protein Extraction from Formalin-Fixed Paraffin-Embedded Tissue for Shotgun Proteomics

Stephen A. Luebker, Scott A. Koepsell

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Urea based protein extraction of formalin-fixed paraffin-embedded (FFPE) tissue provides the most efficient workflow for proteomics due to its compatibility with liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). This study optimizes the use of urea for proteomic analysis of clinical FFPE tissue. A series of protein extraction conditions manipulating temperature and buffer composition were compared to reduce carbamylation introduced by urea and increase protein detection. Each extraction was performed on a randomized pair of serial sections of homogenous FFPE tissue and analyzed with LC-ESI-MS/MS. Results were compared in terms of yield, missed cleavages, and peptide carbamylation. Lowering extraction temperature to 60°C decreased carbamylation at the cost of decreased protein detection and yield. Protein extraction for at least 20 minutes at 95°C followed by 60°C for 2 hours maximized total protein yield while maintaining protein detection and reducing carbamylation by 7.9%. When accounting for carbamylation during analysis, this modified extraction temperature provides equivalent peptide and protein detection relative to the commercially available Qproteome® FFPE Tissue Kit. No changes to buffer composition containing 7 M urea, 2 M thiourea, and 1 M ammonium bicarbonate resulted in improvements to control conditions. Optimized urea in-solution digestion provides an efficient workflow with maximized yields for proteomic analysis of clinically relevant FFPE tissue.

Original languageEnglish (US)
Article number4324987
JournalInternational Journal of Proteomics
Volume2016
DOIs
StatePublished - 2016

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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