Development of tandem time-of-flight instrumentation for the examination of prompt photodissociation of peptides using 193-nm radiation

摘要

The design and incorporation of a decelerating/accelerating cell into a reflectrontime-of-flight mass spectrometer is described for the examination of promptly-formedphotodissociation products of peptide ions. The analytical utility of prompt 193-nmphotodissociation was investigated for model peptides that resemble tryptic digestproducts, as well as for two sets of homologous peptides. The first of these sets includebradykinin, several bradykinin fragments, and two bradykinin mutants with substitutedamino acids. Fragment ion spectra of [M + H]+, [M + Na]+, and [M + Cu]+ werecollected for each of these peptides. The second set of homologous peptides has thesequence XVGVAZG, where variable amino acid X was either arginine, histidine, orlysine, and amino acid Z was either proline, serine, or glycine. Photofragment ionspectra obtained using the new mass spectrometer are compared to results of high energycollision induced dissociation (CID) acquired on a high performance commercialinstrument. The advantages and disadvantages of prompt photodissociation relative toCID are discussed, as well as the advantages of photodissociation using the modifiedinstrument geometry versus that of the post-source decay focusing method.