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Stability of a highly charged noncovalent complex in the gas phase: holomyoglobin
Author(s) -
Chen YuLuan,
Campbell J. M.,
Collings B. A.,
Konermann Lars,
Douglas D. J.
Publication year - 1998
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(19980815)12:15<1003::aid-rcm275>3.0.co;2-#
Subject(s) - chemistry , ion , electrospray ionization , ion cyclotron resonance , mass spectrometry , tandem mass spectrometry , heme , folding (dsp implementation) , ionization , fourier transform ion cyclotron resonance , electrospray , atomic physics , chemical physics , cyclotron , chromatography , physics , biochemistry , organic chemistry , electrical engineering , enzyme , engineering
Gas phase holomyoglobin (hMb) ions in charge states +7 to +21 were formed by electrospray ionization in combination with a continuous‐flow mixing apparatus. Collision cross section measurements show that the highly charged ions are somewhat unfolded in comparison to low charge states but still retain a considerable degree of folding. A new collision model is presented which calculates the relative energies transferred to complexes in tandem mass spectrometry. Tandem mass spectrometry and ion trapping experiments both show that the energies required to dissociate heme from the highly charged heme–protein complexes in the gas phase are similar to those of low charge states, previously shown in literature ion cyclotron resonance experiments to be 0.7–1.0 eV. These energies are comparable to those of the heme binding energy in solution. The results suggest that even for the highly charged hMb ions which have unfolded somewhat, the heme–protein interactions remain relatively unperturbed. © 1998 John Wiley & Sons, Ltd.