EXAMINATION OF AMINO ACID SEQUENCE CONSTITUTING PEPTIDE DEPENDING ON ISOTOPIC RATIO

摘要

It is an object of the present invention, when determining and identifying an amino acid sequence of a peptide using MS, to obtain additional information from the MS for evaluating validity of an amino acid sequence in a candidate list outputted from an identifying engine. The present invention provides a method of testing an amino acid sequence inferred by searching a peptide-related database based on peptide mass information and/or peptide modification information obtained through mass spectrometry on a peptide, the method comprising the steps: (1) calculating a theoretical value of an isotopic ratio for the peptide from the inferred amino acid sequence and/or the peptide modification information; (2) measuring a measured value of the isotopic ratio for the peptide from the peptide mass information; and (3) comparing the theoretical value and the measured value, and evaluating validity of the inferred amino acid sequence from differences between the theoretical value and the measured value.