title: Effects of calcium complexation on heparin-like disaccharides. A combined theoretical, tandem mass spectrometry and ultraviolet experiment.
abstract: BACKGROUND
  In order to shed light on the influence of the Ca(2+) metal cation on the structure of heparin-like (Hp) disaccharides, we have explored the gas-phase structures of both [Hp, -2H](2-) and [Ca(Hp), -3H](-) ions by coupling experimental and theoretical methods.
  
  
  METHODS
  The goal of this work was to (i) provide new evidence of the metal influence on the Hp structure, which can have important biological consequences, and (ii) to study the usefulness of metal complexation for the analytical distinction of Hp isomers. Collision-induced dissociation (CID) and ultraviolet photodissociation (UVPD) fragments, as well as optical spectra recorded in the gas phase for both [Hp, -2H](2-) and [Ca(Hp), -3H](-) complexes were compared for I-H, II-S and III-S isomers of Hp.
  
  
  RESULTS
  In the case of CID fragmentation, a change in the fragmentation pattern was observed upon calcium complexation, with respect to deprotonated Hp.
  
  
  CONCLUSIONS
  Remarkably, when optical spectra are compared in the UV range, the metal effect on the carboxylic group absorption can be detected by an unambiguous blue-shift (~20 nm).
authors.affiliation: Université d'Evry Val d'Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Boulevard François Mitterrand, 91025, Evry, France.|CNRS- UMR 8587.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ortiz
authors.affiliation: Institut Lumière Matière, UMR5306, Université Claude Bernard Lyon1-CNRS, Université de Lyon, 69622, Villeurbanne cedex, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Enjalbert
authors.affiliation: Institut Lumière Matière, UMR5306, Université Claude Bernard Lyon1-CNRS, Université de Lyon, 69622, Villeurbanne cedex, France.
authors.forename: Luke
authors.initials: L
authors.lastname: MacAleese
authors.affiliation: Institut Lumière Matière, UMR5306, Université Claude Bernard Lyon1-CNRS, Université de Lyon, 69622, Villeurbanne cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
authors.affiliation: Université d'Evry Val d'Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Boulevard François Mitterrand, 91025, Evry, France.|CNRS- UMR 8587.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Salpin
mesh_terms: D002118:Calcium / Q000737:chemistry*; D004187:Disaccharides / Q000737:chemistry*; D006493:Heparin / Q000031:analogs & derivatives / Q000737:chemistry; D007536:Isomerism; D008956:Models, Chemical; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D004187:Disaccharides; C464536:heparin disaccharide; D006493:Heparin; D002118:Calcium