Fluorescent modification of N-terminal amino group in peptides for complete sequence analysis using PSD method in MALDI-TOF-MS.

In the sequence analyses of peptides from nucleoprotein in influenza virus, it was very difficult to obtain the sufficient numbers of fragment ions using the post-source decay (PSD) method in MALDI-TOF-MS. Fluorescent modification of the N-terminal amino group in the target peptides was introduced for the PSD measurement. The fluorescently-labelled peptides gave sufficient fragment ions in the PSD spectrum, which leads to the complete sequence analysis of peptide.