De Novo Interpretation of MS/MS Spectra and Protein Identification via Database Searching

Peptide sequencing via tandem mass spectrometry(MS/MS)is one of the most powerful tools in proteomics to identify proteins. A new algorithm was developed for de novo interpretation of MS/MS spectra using graph theory and dynamic alignment between real spectra and theoretical spectra. The trustworthy peptides from de novo interpretation were used in protein identification via database searching. A high throughput statistical analysis of SwissProt and TrEMBL protein databases showed that it's enough to identify a protein in database with three sequence tags of four amino acid residues, two sequence tags of five amino acid residues or one sequence tag of eight amino acid residues.