Vibrational Spectroscopy of Protonated Amino Acids and Peptides and Their Collision-Induced Dissociation Products in the Hydrogen Stretching Region

摘要

A custom-built ESI-Q-ion trap-TOF is demonstrated to collect IRMPD spectra for ESI generated ions. Gas-phase structure and dissociation chemistry of protonated tryptophan is elucidated by comparing the IRMPD spectra of Trp+H~(+) and two of its dissociation products to the theoretical spectra. b_(2) from protonated triglycine is used to reveal the diagnostic NH and OH vibrations for oxazolone and diketopiperazine structures in the hydrogen stretching region. These results demonstrate that covalently bound ions can be photodissociated efficiently using a benchtop OPO. The IRMPD spectra are shown to have resolvable bands, which allow chemical identification of the structures of interest. This approach is hence well suited to the study of chemical structures formed in gas-phase dissociation reactions of amino acids, peptides, and other biomolecules.