Effects of Charge State on Fragmentation Pathways, Dynamics, and Activation Energies of Ubiquitin Ions Measured by Blackbody Infrared Radiative Dissociation

摘要

Blackbody infrared radiative dissociation spectra of the (M+5H)~5+ through (M+11H)~11+ ions of the protein ubiquitin(8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrum- erer. The 5+ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+charge state dissoci- ates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states.