CEITEC-Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno 625 00, Czech Republic.
Phys Chem Chem Phys. 2011 Aug 21;13(31):14215-22. doi: 10.1039/c1cp21071h. Epub 2011 Jul 14.
In this article we present the first systematic study of the additive properties (i.e. degree of additivity) of the carbohydrate-aromatic moiety CH-π dispersion interaction. The additive properties were studied on the β-D-glucopyranose, β-D-mannopyranose and α-L-fucopyranose complexes with the naphthalene molecule by comparing the monodentate (single CH-π) and bidentate (two CH-π) complexes. All model complexes were optimized using the DFT-D approach, at the BP/def2-TZVPP level of theory. The interaction energies were refined using single point calculations at highly correlated ab initio methods at the CCSD(T)/CBS level, calculated as E + (E(CCSD(T))-E(MP2))(Small Basis). Bidentate complexes show very strong interactions in the range from -10.79 up to -7.15 and -8.20 up to -6.14 kcal mol(-1) for the DFT-D and CCSD(T)/CBS level, respectively. These values were compared with the sum of interaction energies of the appropriate monodentate carbohydrate-naphthalene complexes. The comparison reveals that the bidentate complex interaction energy is higher (interaction is weaker) than the sum of monodentate complex interaction energies. Bidentate complex interaction energy corresponds to 2/3 of the sum of the appropriate monodentate complex interaction energies (averaging over all modeled carbohydrate complexes). The observed interaction energies were also compared with the sum of interaction energies of the corresponding previously published carbohydrate-benzene complexes. Also in this case the interaction energy of the bidentate complex was higher (i.e. weaker interaction) than the sum of interaction energies of the corresponding benzene complexes. However, the obtained difference is lower than before, while the bidentate complex interaction energy corresponds to 4/5 of the sum of interaction energy of the benzene complexes, averaged over all structures. The mentioned comparison might aid protein engineering efforts where amino acid residues phenylalanine or tyrosine are to be replaced by a tryptophan and can help to predict the changes in the interactions. The observed results also show that DFT-D correctly describes the CH-π interaction energy and their additive properties in comparison to CCSD(T)/CBS calculated interaction energies. Thus, the DFT-D approach might be used for calculation of larger complexes of biological interest, where dispersion interaction plays an important role.
在本文中，我们首次系统研究了碳水化合物-芳基 CH-π 色散相互作用的加和性质（即加和度）。通过比较单齿（单个 CH-π）和双齿（两个 CH-π）配合物，研究了β-D-吡喃葡萄糖、β-D-吡喃甘露糖和α-L-岩藻糖与萘分子的配合物的加和性质。所有模型配合物均采用 DFT-D 方法，在 BP/def2-TZVPP 理论水平上进行优化。采用单点计算在高度相关的从头算方法（CCSD(T)/CBS 水平，计算为 E + (E(CCSD(T))-E(MP2))(Small Basis)）对相互作用能进行了精细修正。双齿配合物在 DFT-D 和 CCSD(T)/CBS 水平的相互作用能分别为-10.79 至-7.15 和-8.20 至-6.14 kcal mol(-1)，表现出很强的相互作用。这些值与适当的单齿碳水化合物-萘配合物的相互作用能之和进行了比较。比较表明，双齿配合物的相互作用能高于（相互作用较弱）单齿配合物相互作用能之和。双齿配合物的相互作用能对应于所有模拟碳水化合物配合物中单齿配合物相互作用能之和的 2/3。观察到的相互作用能也与相应的先前发表的碳水化合物-苯配合物的相互作用能之和进行了比较。在这种情况下，双齿配合物的相互作用能也高于（即相互作用较弱）相应的苯配合物相互作用能之和。然而，获得的差值低于以前的值，而双齿配合物的相互作用能对应于苯配合物相互作用能之和的 4/5，平均值为所有结构。所述比较可能有助于蛋白质工程，其中要将氨基酸残基苯丙氨酸或酪氨酸替换为色氨酸，并有助于预测相互作用的变化。观察到的结果还表明，与 CCSD(T)/CBS 计算的相互作用能相比，DFT-D 正确描述了 CH-π 相互作用能及其加和性质。因此，DFT-D 方法可用于计算具有重要色散相互作用的生物感兴趣的较大配合物。
