https://doi.org/10.1140/epjd/e2003-00168-7
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 nonose@kobe-u.ac.jp
Received:
10
September
2002
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
