Structure of Pb²⁺-deprotonated dGMP complexes in the gas phase: a combined MS-MS/IRMPD spectroscopy/Ion Mobility study

Jean-Yves Salpin (1) , Luke Macaleese (2) , Fabien Chirot (3) , Philippe Dugourd (2)

1 LAMBE - Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement
2 ILM - Institut Lumière Matière [Villeurbanne]
3 ISA - Institut des Sciences Analytiques

The structure of the Pb²⁺–deprotonated 2′-deoxyguanosine-5′-monophosphate (dGMP) complex, generated in the gas phase by electrospray ionization, was examined by combining tandem mass spectrometry, mid-infrared multiple-photon dissociation (IRMPD) spectroscopy and ion mobility. In the gas phase, the main binding site of Pb²⁺ onto deprotonated dGMP is the deprotonated phosphate group, but the question is whether an additional stabilization of the metallic complex can occur via participation of the carbonyl group of guanine. Such macrochelates indeed correspond to the most stable structures according to theoretical calculations. A multiplexed experimental approach was used to characterize the gas-phase conformation of the metallic complex and hence determine the binding mode of Pb²⁺ with [dGMP]−. MS/MS analysis, observation of characteristic bands by IRMPD spectroscopy, and measurement of the ion mobility collision cross section suggest that gaseous [Pb(dGMP)-H]+ complexes adopt a macrochelate folded structure, which consequently differs strongly from the zwitterionic forms postulated in solution from potentiometric studies.

Mots clés: ION MOBILITY; ELECTRON-CAPTURE; NUCLEIC-ACID BASES; PHOTON DISSOCIATION SPECTROSCOPY; TANDEM MASS-SPECTROMETRY; METAL CATION SIZE; INFRARED-SPECTROSCOPY; BIOMOLECULAR IONS; IRMPD SPECTROSCOPY; UNIMOLECULAR REACTIVITY

Domaines: Chimie théorique et/ou physique; Chimie analytique; Chimie-Physique [physics.chem-ph]

Jean-Yves Salpin, Luke Macaleese, Fabien Chirot, Philippe Dugourd. Structure of Pb²⁺-deprotonated dGMP complexes in the gas phase: a combined MS-MS/IRMPD spectroscopy/Ion Mobility study. Physical Chemistry Chemical Physics, 2014, 16 (27), pp.14127-14138. ⟨10.1039/C4CP00163J⟩. ⟨hal-01345026⟩