Collision Cross Sections of Monomer, Dimer and Tetramer Gas-Phase Ions from Human Hemoglobin

摘要

With the same solution and mass spectrometer operating conditions, fresh human Hb and commercial human Hb give different mass spectra. More intense dimer and monomer ion peaks were seen with commercial Hb. No oxidation was observed with either protein sample. The differences in the spectra appear to derive from some other subtle change to the protein. Gas-phase dimer ions have cross sections intermediate between tetramer and holo-alpha ions. All gas-phase ions have compact structures, similar to the same species in solution. Ions from commercial bovine Hb and oxidized human Hb give cross sections nearly the same as ions from unoxidized human Hb. Thus neither this sequence change or oxidation of Hb make significant changes to the cross sections.