N-terminal charge-driven de novo sequencing by using ASDF-incorporated Curved Field Reflectron

Fixing strong charge at N-terminus of peptide has been reported to be effective derivatization for de novo sequencing. While giving high proton affinity at N-terminus of peptide facilitates the generation of a- and b-ions, it is impossible to differentiate isobaric Ile/Leu residues. Side chain fragmentation generated by high energy CID on MALDI-TOF/TOF has a potential to overcome this issue. On the other hand, a precise assignment of Gln/Lys by the previous MALDI-TOF/TOF is quite difficult due to insufficient MS/MS resolution and accuracy. We will report discrimination of Ile/Leu and a capability of the assignment of Gln/Lys. We will apply newly developed MALDI-TOF/TOF, which has high resolution in MS/MS and a high energy CID at 20keV, to analysis N-terminal derivatized peptides.