Soret Band of the Gas-Phase Ferri-Cytochrome c.
We report the first visible spectrum of a heme-protein in the gas phase. The aim of this work was to provide a reference for the optical absorption of an isolated heme-protein to better understand the influence of protein conformation and fluctuation and of solvent on its optical properties. After laser irradiation of gas-phase cytochrome c (cyt c), electron emission is observed. Electron photodetachment yield of cyt c 6- was recorded in the region of the Soret band of the porphyrin group, showing a maximum at 410 nm. Our results are compared with optical spectra of gas-phase heme and of cyt c in solution. We discuss the influence of the polypeptide chain and of the solvent on both the position and the broadening of the Soret band. Action spectrum of gas-phase cyt c is close to the absorption of native cyt c in solution, suggesting an efficient protection of the heme group from solvent accessibility by the polypeptide chain and similar interactions between the two moieties in solution and the gas phase.
†Université Lyon 1, Lyon, France.|‡CNRS, LASIM UMR 5579, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.|§CNRS, Institut des Sciences Analytique UMR 5180, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Claire
C
Brunet
†Université Lyon 1, Lyon, France.|‡CNRS, LASIM UMR 5579, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Rodolphe
R
Antoine
†Université Lyon 1, Lyon, France.|§CNRS, Institut des Sciences Analytique UMR 5180, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Jérôme
J
Lemoine
†Université Lyon 1, Lyon, France.|‡CNRS, LASIM UMR 5579, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Philippe
P
Dugourd
action spectra; charge transfer; electron photodetachment; heme; mass spectrometry; porphyrin; protein; solvation