Coates Rebecca A, McNary Christopher P, Boles Georgia C, Berden Giel, Oomens Jos, Armentrout P B
Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
Phys Chem Chem Phys. 2015 Oct 21;17(39):25799-808. doi: 10.1039/c5cp01500f.
Structural characterization of gas-phase ions of cysteine (Cys) and cysteine methyl ester (CysOMe) complexed to zinc and cadmium is investigated by infrared multiple photon dissociation (IRMPD) action spectroscopy using a free electron laser in combination with density functional theory calculations. IRMPD spectra are measured for Zn(Cys-H), Cd(Cys-H), Zn(CysOMe-H), Cd(CysOMe-H) and CdCl(+)(CysOMe) and are accompanied by quantum mechanical calculations of the predicted linear absorption spectra at the B3LYP/6-311+G(d,p) (Zn(2+) complexes) and B3LYP/def2TZVP levels (Cd(2+) complexes). On the basis of these experiments and calculations, the conformation that best reproduces the IRMPD spectra for the complexes of the deprotonated amino acids, M(Cys-H) and M(CysOMe-H), is a charge-solvated (CS) tridentate structure where the metal dication binds to the amine and carbonyl groups of the amino acid backbone and the deprotonated sulfur atom of the side chain, [N,CO,S(-)]. The intact amino acid complex, CdCl(+)(CysOMe) binds in the equivalent motif [N,CO,S]. These binding motifs are in agreement with the predicted ground structures of these complexes at the B3LYP, B3LYP-GD3BJ (with empirical dispersion corrections), B3P86, and MP2(full) levels.
利用自由电子激光结合密度泛函理论计算，通过红外多光子解离（IRMPD）作用光谱研究了与锌和镉络合的半胱氨酸（Cys）和半胱氨酸甲酯（CysOMe）气相离子的结构特征。测量了Zn（Cys-H）、Cd（Cys-H）、Zn（CysOMe-H）、Cd（CysOMe-H）和CdCl(+)(CysOMe)的IRMPD光谱，并伴随有在B3LYP/6-311+G(d,p)（Zn(2+)络合物）和B3LYP/def2TZVP水平（Cd(2+)络合物）下预测的线性吸收光谱的量子力学计算。基于这些实验和计算，对于去质子化氨基酸M（Cys-H）和M（CysOMe-H）的络合物，最能重现IRMPD光谱的构象是电荷溶剂化（CS）三齿结构，其中金属二价阳离子与氨基酸主链的胺基和羰基以及侧链的去质子化硫原子[N,CO,S(-)]结合。完整的氨基酸络合物CdCl(+)(CysOMe)以等效基序[N,CO,S]结合。这些结合基序与在B3LYP、B3LYP-GD
