Glycopeptide analyzer

A glycopeptide analyzer configured to perform a structural analysis on glycoforms of a glycoprotein using an analyzing device including a liquid chromatograph coupled with a mass spectrometer capable of MS/MS analysis, the glycopeptide analyzer comprising:

• a spectrum creator configured to create an MS/MS spectrum for each elution time, based on data acquired by analyzing a sample containing glycopeptides originating from a target glycoprotein by the analyzing device;
• a peptide mass calculator configured to select a glycopeptide-related spectrum which is likely to have originated from a glycopeptide, from a plurality of MS/MS spectra created by the spectrum creator for different elution times, and to calculate a mass of a peptide in the selected glycopeptide based on the glycopeptide-related spectrum;
• a spectrum similarity determiner configured to determine a similarity between the glycopeptide-related spectrum and each of the other MS/MS spectra or each MS/MS spectrum corresponding to a specific range of time;
• a glycoform-related spectrum selector configured to select, as a glycoform-related spectrum for the glycopeptide concerned, an MS/MS spectrum having a high level of similarity with the glycopeptide-related spectrum;
• a glycoform elution-time range estimator configured to determine a distribution of a frequency of occurrence of the selected glycoform-related spectrum on a time axis, and to estimate a glycoform elution-time range based on the distribution;
• and
• a glycan composition estimator configured to select, from ion peaks detected on an MS spectrum collected within the estimated glycoform elution-time range, an ion peak corresponding to a mass greater than a peptide mass calculated by the peptide mass calculator, and to estimate a glycan composition by using the ion peak.