Sequencing Data-Encoded Peptides from Tandem Mass Spectra

Peptide sequencing is important in decoding data stored in a data-encoded peptide. Tandem mass spectrometry (MS/MS) is particularly useful for peptide sequencing. In a computer-implemented method for sequencing the data-encoded peptide from an experimental spectrum, raw data of the experimental spectrum are first preprocessed to remove uninterpretable peaks to yield preprocessed data. A first set of one or more candidate sequences contending for a peptide sequence of the peptide is identified from a spectrum graph. The spectrum graph is formed according to the preprocessed data rather than the raw data for generating a fewer number of candidate sequences to thereby reduce a time cost in sequencing. The first candidate-sequence set is then processed to estimate the peptide sequence to thereby obtain a set of peptide-sequence estimate(s). Each estimate is verified whether it is invalid. The set of peptide-sequence estimate(s) is purged to remove any invalid estimate.