The structural evolution of ubiquitin after transfer into the gas phase was studied by electron capture dissociation. Site-specific fragment yields show that ubiquitin's solution fold is overall unstable in the gas phase, but unfolding caused by loss of solvent is slowest in regions stabilized by salt bridges.
For characterization of sequence and posttranslational modifications, molecular and fragment ion mass data from ionizing and dissociating a protein in the mass spectrometer are far more specific than are masses of peptides from the protein's digestion. We extend the approximately 500-residue, approximately 50-kilodalton (kD) dissociation limitation of this… (More)
A recently developed methodology for the characterization of complex proteomes, top-down Fourier transform mass spectrometry (FTMS), is applied for the first time to a plant proteome, that of the model plant Arabidopsis thaliana. Of the 3000 proteins predicted by the genome sequence, 97 were recently identified in two separate "bottom-up" mass spectrometry… (More)