Fig. 5
From: Large scale analysis of amino acid substitutions in bacterial proteomics
X-axis shows the number of false peptides identifications of speptide in the search the spectra of H. pylori H13-1 against the spectral library created from H. pylori 26695 spectra. False identifications assigned by additional Mascot search spectra of H. pylori H13-1 against protein database constructed from the annotated genome of H. pylori H13-1. Y-axis shows the number of peptides identifications of H. pylori H13-1 spectra in different speptide decoy searches: (i) shift of all MS1 peaks at +20 Th, (ii) shift of all MS2 peaks at +20 Th, (iii) library constructed from N. gonorrhoeae FA1090 spectra, (iv) library constructed from N. gonorrhoeae n01.08 spectra. The number of decoy identifications is normalized in a way that the number of spectrum-peptide pairs is the same in direct and decoy searches