ANYL 64 |
| Approaches for enhancing proton affinity of tryptic peptides, such as guanidination, have been utilized for increase ionization efficiency in MALDI-TOF mass spectrometric peptide fingerprinting. Many such approaches involve adjustment of pH and removal of excess reagents after chemical modification of the peptides. Incomplete reaction could complicate the resulting peptide mass map. We demonstrated the utility of amidine formation, upon reacting peptides with imidoester, which results in higher proton affinity than the amine form and thus produce more protonated peptide ions in the plume. The reaction is complete in 1 h at RT and pH 8. We tested the efficacy of various imidoesters and found that picolinimidate was most efficient. Signal-to-noise ratio of model peptides was enhanced about 10-fold. Unlike guanidination, the reaction takes place at the N-terminal amine as well as at the side chain amine of lysine. Thus the method makes many previously undetected peptides, including low molecular weigh peptides not detectable due to matrix interference, detectable and enhances confidence in protein identification by peptide mass fingerprinting.
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General Posters
7:00 PM-9:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Analytical Chemistry |
