title: An experimental and theoretical investigation of gas-phase reactions of Ca2+ with glycine.
abstract: The gas-phase reactions between Ca(2+) and glycine ([Ca(gly)](2+)) have been investigated through the use of mass spectrometry techniques and B3-LYP/cc-pWCVTZ density functional theory computations. The major peaks observed in the electrospray MS/MS spectrum of [Ca(gly)](2+) correspond to the formation of the [Ca,C,O(2),H](+), NH(2)CH(2) (+), CaOH(+), and NH(2)CH(2)CO(+) fragment ions, which are produced in Coulomb explosion processes. The computed potential energy surface (PES) shows that not only are these species the most stable product ions from a thermodynamic point of view, but they may be produced with barriers lower than for competing processes. Carbon monoxide is a secondary product, derived from the unimolecular decomposition of some of the primary ions formed in the Coulomb explosions. In contrast to what is found for the reactions of Ca(2+) with urea ([Ca(urea)](2+)), minimal unimolecular losses of neutral fragments are observed for the gas-phase fragmentation processes of [Ca(gly)](2+), which is readily explained in terms of the topological differences between their respective PESs.
authors.affiliation: Departamento de Química, C-9, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain.
authors.forename: Inés
authors.initials: I
authors.lastname: Corral
authors.forename: Otilia
authors.initials: O
authors.lastname: Mó
authors.forename: Manuel
authors.initials: M
authors.lastname: Yáñez
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Salpin
authors.forename: Jeanine
authors.initials: J
authors.lastname: Tortajada
authors.forename: Damian
authors.initials: D
authors.lastname: Moran
authors.forename: Leo
authors.initials: L
authors.lastname: Radom
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002413:Cations, Divalent / Q000737:chemistry; D005740:Gases; D005998:Glycine / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry
chemical_list: D002413:Cations, Divalent; D005740:Gases; D014508:Urea; D002118:Calcium; D005998:Glycine