Structures and reactions of biomolecular ions produced with electrospray ionization
Department of Chemistry, Faculty of Science, Kobe University, Kobe 657-8501, Japan
Corresponding author: a email@example.com
Published online: 3 July 2003
Photo-induced reaction of [Fe(III)-protoporphyrin]+ (hemin+) ions solvated with dimethylsulfoxide (DMSO) is investigated by using a tandem mass spectrometer with electrospray ionization. We measure the photodissociation yields of mass-selected hemin+(DMSO)n clusters for . The mass spectra of the fragment ions show the β-cleavage of carboxymethyl groups in addition to the evaporation of solvent molecules. Yield of the β-cleavage reaction is found to depend strongly on the excitation energy and the number of solvent molecules. We also examine photo-induced reactions of multiply-charged cytochrome c ions, (). Photoionization is found to be the dominant process for the lower charged states () and its yield decreases rapidly with increasing the charge. The photoionization is ascribed to the emission of electron by multiphoton excitation of heme under the influence of Coulomb attractive potential arising from the charges in the polypeptide chain. Model calculations of the Coulomb potential suggest that the structure of the polypeptide chain is completely elongated.
PACS: 36.40.-c – Atomic and molecular clusters / 71.22.-f – Electronic structure of nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003