Structures and fragmentations of cobalt(II)-cysteine complexes in the gas phase.
The electronebulization of a cobalt(II)/cysteine(Cys) mixture in water/methanol (50/50) produced mainly cobalt-cationized species. Three main groups of the Co-cationized species can be distinguished in the ESI-MS spectrum: (1) the cobalt complexes including the cysteine amino acid only (they can be singly charged, for example, [Co(Cys)n- H]+ with n = 1-3 or doubly charged such as [Co + (Cys)2]2+); (2) the cobalt complexes with methanol: [Co(CH3OH)n- H]+ with n = 1-3, [Co(CH3OH)4]2+; and (3) the complexes with the two different types of ligands: [Co(Cys)(CH3OH) - H]+. Only the singly charged complexes were observed. Collision-induced dissociation (CID) products of the [Co(Cys)2]2+, [Co(Cys)2 - H]+ and [Co(Cys) - H]+ complexes were studied as a function of the collision energy, and mechanisms for the dissociation reactions are proposed. These were supported by the results of deuterium labelling experiments and by density functional theory calculations. Since [Co(Cys) - H]+ was one of the main product ions obtained upon the CID of [Co(Cys)2]2+ and of [Co(Cys)2 - H]+ under low-energy conditions, the fragmentation pathways of [Co(Cys) - H]+ and the resulting product ion structures were studied in detail. The resulting product ion structures confirmed the high affinity of cobalt(II) for the sulfur atom of cysteine.
Buchmann
William
W
Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement (LAMBE), Université d'Evry-Val d'Essonne, CNRS UMR 8587, Bât. Maupertuis, Bd. F. Mitterrand, 91025 Evry Cedex, France. William.buchmann@chimie.univ-evry.fr
Spezia
Riccardo
R
Tournois
Guewen
G
Cartailler
Thierry
T
Tortajada
Jeanine
J
D003035:Cobalt / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D005740:Gases; D021241:Spectrometry, Mass, Electrospray Ionization
D005740:Gases; D003035:Cobalt; C025913:cobaltous nitrate; D003545:Cysteine