Matrix-assisted laser desorption/ionization imaging protocol for in situ characterization of tryptic peptide identity and distribution in formalin-fixed tissue

Rapid Commun Mass Spectrom. 2013 Mar 30;27(6):655-70. doi: 10.1002/rcm.6488.

Abstract

Rationale: Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry provides the means to map the in situ distribution of tryptic peptides in formalin-fixed clinical tissue samples. The ability to analyze clinical samples is of great importance to further developments in the imaging field. However, there is a requirement in this field of research for additional methods describing the characterization of tryptic peptides by MALDI imaging.

Methods and results: This protocol gives highly detailed instructions, with examples, for (1) successfully performing tryptic peptide MALDI imaging on formalin-fixed cancer tissue using a MALDI-TOF/TOF MS instrument, (2) tentatively generating identifications through nLC/MS/MS, and (3) validating these identifications by in situ MS/MS of peptides of interest.

Conclusions: This protocol provides a detailed and straightforward description of the methods required for groups new to MALDI imaging to begin analysis of formalin-fixed clinical samples.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Calibration
  • Formaldehyde / chemistry
  • Histocytological Preparation Techniques / methods*
  • Humans
  • Image Processing, Computer-Assisted / methods
  • Molecular Imaging / methods*
  • Molecular Sequence Data
  • Neoplasms / chemistry
  • Peptide Fragments / analysis*
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*
  • Tandem Mass Spectrometry
  • Trypsin / metabolism

Substances

  • Peptide Fragments
  • Formaldehyde
  • Trypsin