Automated protein identification by the combination of MALDI MS and MS/MS spectra from different instruments

J Proteome Res. 2005 Jan-Feb;4(1):71-4. doi: 10.1021/pr0498584.

Abstract

The identification of proteins separated on two-dimensional gels is most commonly performed by trypsin digestion and subsequent matrix-assisted laser desorption ionization (MALDI) with time-of-flight (TOF). Recently, atmospheric pressure (AP) MALDI coupled to an ion trap (IT) has emerged as a convenient method to obtain tandem mass spectra (MS/MS) from samples on MALDI target plates. In the present work, we investigated the feasibility of using the two methodologies in line as a standard method for protein identification. In this setup, the high mass accuracy MALDI-TOF spectra are used to calibrate the peptide precursor masses in the lower mass accuracy AP-MALDI-IT MS/MS spectra. Several software tools were developed to automate the analysis process. Two sets of MALDI samples, consisting of 142 and 421 gel spots, respectively, were analyzed in a highly automated manner. In the first set, the protein identification rate increased from 61% for MALDI-TOF only to 85% for MALDI-TOF combined with AP-MALDI-IT. In the second data set the increase in protein identification rate was from 44% to 58%. AP-MALDI-IT MS/MS spectra were in general less effective than the MALDI-TOF spectra for protein identification, but the combination of the two methods clearly enhanced the confidence in protein identification.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Automation
  • Bacterial Proteins / analysis
  • Fungal Proteins / analysis
  • Mass Spectrometry / instrumentation
  • Mass Spectrometry / methods
  • Proteins / analysis*
  • Proteomics / instrumentation*
  • Proteomics / methods
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / instrumentation
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*

Substances

  • Bacterial Proteins
  • Fungal Proteins
  • Proteins