2D-O1-0950 PDF
Novel fragmentation mass spectrometry employing hydrogen attachment/abstraction dissociation (HAD) and several gas-phase neutral radicals (H•/O• /OH•)
Gas-phase neutral radicals (H•/O•/OH•) were introduced into the quadrupole ion trap containing biomolecule ions to obtain the radical-induced dissociation spectrum. A microwave driven radical source was developed to generate a wide variety of radical species (H•/O•/OH•). A model peptide of 1+ substance P (RPKPQQFFGLM-NH2) was subjected to a reaction with neutral radicals produced from water-vapor microwave discharge. Abundant a-/c- type fragment ions were observed with a sequence coverage of over 70% for the reaction time of 500 ms. In contrast to previously reported hydrogen attachment/abstraction dissociation (HAD) using a thermal cracking cell, abundant H• deficient ion ([M+H-H]+•) and O• adduct ion ([M+H+O]+) were observed whereas H• attachment to the precursor ion ([M+2H]+•) was unobserved. This result indicates that H• was abstracted from the precursor ion by OH• radicals, but not H• radicals. Meanwhile, neither H• attachment/abstraction to/from the peptide ions nor any fragmentations were observed by microwave discharge of pure H2 gas. This result implies that H• attachment/abstraction to/from the peptide backbone require corresponding higher threshold energies than H• temperature generated by the microwave discharge.