In this work, we studied the interactions between cyclic glycine-alanine dipeptide c(GA) and gold nanoclusters (Au_nNCs, where n = 2–10) using density functional theory (DFT), atoms-in-molecules theory (AIM), and natural bond orbital analysis (NBO). This dipeptide (DP) consists of two amino acid residues (glycine and alanine); thus, the preference of both residues for binding to gold atoms was examined. The preference of alanine residue to the studied Au_nNCs was found to be greater than that of glycine residue. Two types of interactions were exhibited between the Au_nNCs and c(GA), the partially-covalent partially-electrostatic type and electrostatic interaction. Performance of two DFT functionals and different basis sets is assessed. The results benchmark the importance of the DFT functional with dispersion and long-range corrections, as well as the polarization functions in the basis sets for the gold lusters-peptide binding. The binding energy (ΔE_bind) values of the c(GA)−Au_nNCs complexes in gas and water implicit solvent were compared with those previously published for cyclic glycine-glycine DP−Au_nNCs complexes. It was found that the ΔE_bind values of the former complexes are greater than those of latter ones in water solvent.

 在这项工作中，我们使用密度泛函理论 (DFT)、分子中原子理论 (AIM)研究了环状甘氨酸-丙氨酸二肽c (GA) 和金纳米簇 (Au _n NCs，其中n = 2-10) 之间的相互作用和自然键轨道分析 (NBO)。这种二肽（DP）由两个氨基酸残基（甘氨酸和丙氨酸）组成；因此，检查了两个残基与金原子结合的偏好。发现丙氨酸残基对研究的 Au _n NCs 的偏好大于甘氨酸残基。_{Au n} NCs和c之间表现出两种类型的相互作用（GA），部分共价部分静电型和静电相互作用。评估两个 DFT 泛函和不同基组的性能。结果基准化了具有色散和远程校正的 DFT 泛函的重要性，以及金光泽-肽结合的基组中的极化函数。将气体和水隐含溶剂中c (GA)-Au _n NCs 复合物的结合能 (Δ E _bind ) 值与先前公布的环状甘氨酸-甘氨酸 DP-Au _n NCs 复合物的结合能值进行了比较。发现前者配合物的ΔE_结合值大于后者在水溶剂中的结合值。