Owen Cameron J, Boles Georgia C, Berden Giel, Oomens Jos, Armentrout P B
1 Department of Chemistry, University of Utah, Salt Lake City, USA.
2 FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands.
Eur J Mass Spectrom (Chichester). 2019 Feb;25(1):97-111. doi: 10.1177/1469066718792902. Epub 2018 Dec 7.
The gas-phase structures of zinc and cadmium complexes of lysine (Lys) are investigated via a combination of infrared multiple photon dissociation action spectroscopy and ab initio quantum chemical calculations. In order to unambiguously identify the experimentally observed species, [Zn(Lys-H)] and CdCl(Lys), the action spectra were compared to linear absorption spectra calculated at the B3LYP level of theory, using 6-311+G(d,p) and def2-TVZP basis sets for the zinc and cadmium systems, respectively. Single point energies were also calculated at the B3LYP, B3P86, MP2, and B3LYP-GD3BJ (accounting for empirical dispersion) levels of theory using larger basis sets. Identification of the experimentally formed isomers is possible through good agreement between infrared multiple photon dissociation action spectra and the theoretically predicted spectra. The [Zn(Lys-H)] complex adopts a tridentate orientation involving the amino acid backbone amine and deprotonated carboxylic acid groups as well as the side-chain amine group, [N,CO,N]. The CdCl(Lys) complex similarly adopts a tridentate chelation involving the amino acid backbone amine and carbonyl groups, as well as the side-chain amine group, [N,CO,N]. In both cases, the identified complexes are the lowest energy gas-phase structures at all levels of theory.
通过红外多光子解离作用光谱和从头算量子化学计算相结合的方法，研究了赖氨酸（Lys）的锌和镉配合物的气相结构。为了明确识别实验观察到的物种[Zn(Lys-H)]和CdCl(Lys)，将作用光谱与在理论B3LYP水平下计算的线性吸收光谱进行了比较，锌体系使用6-311+G(d,p)基组，镉体系使用def2-TVZP基组。还使用更大的基组在理论的B3LYP、B3P86、MP2和B3LYP-GD3BJ（考虑经验色散）水平下计算了单点能量。通过红外多光子解离作用光谱与理论预测光谱之间的良好一致性，可以识别实验形成的异构体。[Zn(Lys-H)]配合物采用三齿取向，涉及氨基酸主链胺、去质子化的羧酸基团以及侧链胺基团，即[N,CO,N]。CdCl(Lys)配合物同样采用三齿螯合，涉及氨基酸主链胺和羰基以及侧链胺基团，即[N,CO,N]。在这两种情况下，所识别的配合物在所有理论水平下都是能量最低的气相结构。
