Mass Spectra Interpretation and the Interest of SpecFit for Identifying Uncommon Modifications

SpecOMS [8] is a software designed to identify peptides from spectra obtained by mass spectrometry experiments. In this paper, we make a specific focus on SpecFit, an optional module of the SpecOMS software. Because SpecOMS is particularly fast, SpecFit can be used within SpecOMS to further investigate spectra whose mass does not necessarily coincide with the mass of its corresponding peptide, and consequently to suggest modifications for these peptides, together with their locations. In this paper, we show that SpecFit is able to identify uncommon peptide modifications that are generally not detected by other software. In that sense, SpecFit is of particular interest since, even today, a large majority of spectra remain uninterpreted.