| 摘要 |
PROBLEM TO BE SOLVED: To identify a peptide and a modification site with high accuracy even for a peptide that is subjected to posttranslational modification that cannot easily be identified in an ordinary database retrieval.SOLUTION: De novo sequencing is executed on a MSspectrum derived from a target peptide in a low m/z direction using as the origin a plurality of peaks where ion intensity is relative large, and a plurality of tag candidates are extracted by estimating an amino acid sequence (S1-S3). The tag candidates whose peaks as the origin differ are compared, those having an amino acid sequence in common are detected assuming that their reliability is high, and a sequence tag based on the amino acid sequence is created (S4). A posttranslational modification molecule is estimated from a difference between the start m/z's and between the finish m/z's of the amino acid sequence in the plurality of detected tag candidates (S5). A target peptide is identified by executing a sequence tag search using the sequence tag and modification molecule information as search conditions (S6-S7). |
