Salpin Jean-Yves, MacAleese Luke, Chirot Fabien, Dugourd Philippe
Université d'Evry Val d'Essonne, Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Boulevard François Mitterrand, 91025 Evry, France.
Phys Chem Chem Phys. 2014 Jul 21;16(27):14127-38. doi: 10.1039/c4cp00163j. Epub 2014 Jun 5.
The structure of the Pb(2+)-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 Pb(2+) 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 Pb(2+) 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.
通过电喷雾电离在气相中生成的Pb(2+)去质子化2'-脱氧鸟苷-5'-单磷酸（dGMP）配合物的结构，采用串联质谱、中红外多光子解离（IRMPD）光谱和离子淌度相结合的方法进行了研究。在气相中，Pb(2+)与去质子化dGMP的主要结合位点是去质子化的磷酸基团，但问题是金属配合物是否能通过鸟嘌呤羰基的参与实现额外的稳定。根据理论计算，这种大环螯合物确实对应于最稳定的结构。采用一种多重实验方法来表征金属配合物的气相构象，从而确定Pb(2+)与dGMP的结合模式。MS/MS分析、通过IRMPD光谱观察特征谱带以及测量离子淌度碰撞截面表明，气态Pb(dGMP)-H配合物采用大环螯合物折叠结构，因此与电位滴定研究在溶液中假定的两性离子形式有很大不同。
