Extracting the Signal from MALDI-TOF Spectra by Using the Expected Isotopic Distribution

• Activity Number: 641
• Type: Topic Contributed
• Date/Time: Thursday, August 2, 2012 : 10:30 AM to 12:20 PM
• Sponsor: Biometrics Section
• Author(s): Tomasz Burzykowski*+
• Companies: Hasselt University
• Keywords: mass spectrometry ; MALDI-TOF ; signal extraction ; tandem MS

Abstract

Valkenborg et al (2009) proposed a strategy for an efficient extraction of the relevant signal from MALDI TOF spectra. In a nutshell, in a high resolution spectrum, a peptide should be represented by a sequence of peaks corresponding to the isotopic distribution of the peptide. The expected configuration can be efficiently computed by using the information contained in existing protein databases (Valkenborg et al., 2008). The similarity between the observed and expected configurations can be summarized by using, e.g., Pearson's ?2 statistic. By extracting from a spectrum only the measurements with a low value of the statistic, which are most likely peptide related, we can greatly reduce the amount of data that needs to be additionally analyzed in, e.g., the identification step in the tandem MS. In this paper, we consider further the possibility of using Pearson's ?2 statistic, which captures the similarity between the observed and expected configuration of the peaks in a spectrum, to increase the sensitivity and specificity of peptide identification in tandem MS based on correlative database searching algorithms like SEQUEST.