Research & Teaching Faculty

Default Header Image

Tandem mass spectrometry of protein-protein complexes: Cytochrome c-cytochrome b(5)

TitleTandem mass spectrometry of protein-protein complexes: Cytochrome c-cytochrome b(5)
Publication TypeJournal Article
Year of Publication2002
AuthorsMauk, MR, Mauk, AG, Chen, YL, Douglas, DJ
JournalJournal of the American Society for Mass Spectrometry
Volume13
Pagination59-71
Date PublishedJan
Type of ArticleArticle
ISBN Number1044-0305
KeywordsACTIVATION, BINDING, COLLISION-INDUCED DISSOCIATION, CROSS-SECTIONS, ELECTROSPRAY-IONIZATION, GAS-PHASE, INTERNAL ENERGY, ION-TRAP, NONCOVALENT COMPLEXES, YEAST ISO-1-FERRICYTOCHROME-C
Abstract

An improved method to interpret triple quadrupole MS/MS experiments of complexes of large ions is presented and applied to a study of the complex formed by the proteins cytochrome c and cytochrome b(5). Modeling of the activation and dissociation process shows that most of the reaction occurs near the collision cell exit where ions have the highest internal energies. Experiments at different collision cell pressures or with different collision gases (Ne, Ar, Kr) are interpreted with a previously proposed collision model (Chen et al., Rapid Commun. Mass Spectrom. 1998, 12, 1003-1010) to calculate the internal energy added to ions to cause dissociation. Small but systematic differences under different experimental conditions are attributed to different times available for reaction. A method to correct for this is presented. Ne, Ar, and Kr are found to have similar energy transfer efficiencies. Complexes of cytochrome c and cytochrome b5 are detected in ESI mass spectra but with abundances less than expected from the solution equilibrium. Dissociation of the cytochrome c-cytochrome b(5) complexes with charge k gives as the most abundant fragments, cytochrome b(5)(+3) and cytochrome c(+(k+3)). Adding charges to the complex destabilizes it. A series of cytochrome c variants with Lys residues thought to be involved in solution binding replaced by Ala showed no differences in the energy required to induce dissociation of the gas phase complex. The implications for the binding of the gas phase ions are inconclusive. (J Am Soc Mass Spectrom 2002, 13, 59-71) ((C)) 2002 American Society for Mass Spectrometry.

URL<Go to ISI>://000172868300007