title: Probing electrostatic interactions and structural changes in highly charged protein polyanions by conformer-selective photoelectron spectroscopy.
abstract: We have recorded the first conformer-selective photoelectron spectra of a protein polyanion in the gas-phase. Bovine cytochrome c protein was studied in 8 different negative charge states ranging from 5- to 12-. Electron binding energies were extracted for all charge states and used as a direct probe of intramolecular Coulomb repulsion. Comparison of experimental results with simulations shows that the experimental outcome can be reproduced with a simple electrostatic model. Energetics are consistent with a structural transition from a folded to an unfolded conformational state of the protein as the number of charges increases. Furthermore, the additional ion-mobility data show that the onset of unfolding can be assigned to charge state 6- where three conformers can be distinguished.
authors.affiliation: Institut für Physikalische Chemie, Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Vonderach
authors.forename: Oli T
authors.initials: OT
authors.lastname: Ehrler
authors.forename: Katerina
authors.initials: K
authors.lastname: Matheis
authors.forename: Tatjana
authors.initials: T
authors.lastname: Karpuschkin
authors.forename: Evangelos
authors.initials: E
authors.lastname: Papalazarou
authors.forename: Claire
authors.initials: C
authors.lastname: Brunet
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Patrick
authors.initials: P
authors.lastname: Weis
authors.forename: Oliver
authors.initials: O
authors.lastname: Hampe
authors.forename: Manfred M
authors.initials: MM
authors.lastname: Kappes
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
mesh_terms: D000818:Animals; D002417:Cattle; D045304:Cytochromes c / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D056951:Photoelectron Spectroscopy / Q000379:methods*; D000071228:Polyelectrolytes; D011108:Polymers / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D055672:Static Electricity
chemical_list: D045304:Cytochromes c; D005740:Gases; D000071228:Polyelectrolytes; D011108:Polymers