| 摘要 |
<P>PROBLEM TO BE SOLVED: To identify peptide with high precision even with respect to N-bound sugar peptide although peptide identification may become difficult because of m/z displacement since NH<SB POS="POST">3</SB>or H<SB POS="POST">2</SB>O is detached by preferential cyclization in the case where N-terminal amino acid residue is glutamine or cysteine of methyl carbamide. <P>SOLUTION: When implementing de novo sequence processing on a peak train indicating a sugar chain composition that appears in Ms<SP POS="POST">2</SP>spectrum, the presence/absence of m/z displacement caused by NH<SB POS="POST">3</SB>or H<SB POS="POST">2</SB>O detachment is estimated from a mass charge ratio difference between one of the peaks and MS<SP POS="POST">2</SP>precursor (S4, S5). Further, the presence/absence of similar m/z displacement is also estimated from a mass charge ratio difference between a triplet peak characteristic for N-bound sugar peptide on Ms<SP POS="POST">2</SP>spectrum and a triplet peak on MS<SP POS="POST">1</SP>spectrum (S6, S7). If the presence of cyclization of N-terminal amino acid residue is determined, that is defined as one of search conditions in database search, thereby improving peptide identification precision. <P>COPYRIGHT: (C)2013,JPO&INPIT |
