Departament de Química , Universitat Autònoma de Barcelona , 08193 Cerdanyola del Vallés , Barcelona , Spain.
Dipartimento di Chimica e Farmacia , Università di Sassari , Via Vienna 2 , I-07100 Sassari , Italy.
Inorg Chem. 2018 Apr 16;57(8):4456-4469. doi: 10.1021/acs.inorgchem.8b00134. Epub 2018 Apr 3.
The interaction of metallodrugs with proteins influences their transport, uptake, and mechanism of action. In this study, we present an integrative approach based on spectroscopic (EPR) and computational (docking) tools to elucidate the noncovalent binding modes of various VO compounds with lysozyme, a prototypical model of protein receptor. Five VO-flavonoid drug candidates formed by quercetin (que), morin (mor), 7,8-dihydroxyflavone (7,8-dhf), chrysin (chr), and 5-hydroxyflavone (5-hf)-effective against several osteosarcoma cell lines-and two benchmark VO species of acetylacetone (acac) and catechol (cat) are evaluated. The results show a gradual variation of the EPR spectra at room temperature, which is associated with the strength of the interaction between the square pyramidal complexes [VOL] and the surface residues of lysozyme. The qualitative strength of the interaction from EPR is [VO(que)] ≈ [VO(mor)] > [VO(7,8-dhf)] > [VO(chr)] ≈ [VO(5-hf)] > [VO(acac)] ≈ [VO(cat)]. This observation is compared with protein- ligand docking calculations with GOLD software examining the GoldScore scoring function ( F), for which hydrogen bond and van der Waals contact terms have been optimized to account for the surface interaction. The best predicted binding modes display an energy trend in good agreement with the EPR spectroscopy. Computation indicates that the strength of the interaction can be predicted by the F value and depends on the number of OH or CO groups of the ligands that can interact with different sites on the protein surface and, more particularly, with those in the vicinity of the active site of the enzyme. The interaction strength determines the type of signal revealed ( rigid limit, slow tumbling, or isotropic) in the EPR spectra. Spectroscopic and computational results also suggest that there are several sites with comparable binding energy, with the V complexes distributing among them in a bound state and in aqueous solution in an unbound state. This kind of study and analysis could be generalized to determine the noncovalent binding modes of a generic metal species with a generic protein.
金属药物与蛋白质的相互作用会影响它们的运输、摄取和作用机制。在这项研究中，我们提出了一种基于光谱（EPR）和计算（对接）工具的综合方法，以阐明各种 VO 化合物与溶菌酶（蛋白质受体的典型模型）的非共价结合模式。评估了五种 VO-类黄酮药物候选物，它们是由槲皮素（que）、桑色素（mor）、7,8-二羟基黄酮（7,8-dhf）、白杨素（chr）和 5-羟基黄酮（5-hf）组成的，对几种骨肉瘤细胞系有效-以及两种基准 VO 物种乙酰丙酮（acac）和儿茶酚（cat）。结果表明，在室温下，EPR 光谱会发生逐渐变化，这与四方锥配合物[VOL]与溶菌酶表面残基之间相互作用的强度有关。EPR 定性强度的相互作用为[VO（que）]≈[VO（mor）]＞[VO（7,8-dhf）]＞[VO（chr）]≈[VO（5-hf）]＞[VO（acac）]≈[VO（cat）]。将观察结果与使用 GOLD 软件进行的蛋白质配体对接计算进行了比较，该软件使用 GoldScore 评分函数（F）进行了检查，该函数对氢键和范德华接触项进行了优化，以考虑表面相互作用。最佳预测结合模式显示出与 EPR 光谱非常吻合的能量趋势。计算表明，相互作用的强度可以通过 F 值来预测，并且取决于配体的 OH 或 CO 基团的数量，这些基团可以与蛋白质表面的不同部位相互作用，更特别是与酶的活性部位附近的部位相互作用。相互作用的强度决定了在 EPR 光谱中揭示的信号类型（刚性极限、缓慢翻滚或各向同性）。光谱和计算结果还表明，存在几个具有可比结合能的位点，其中 V 配合物以结合状态分布在它们之间，而在水溶液中以非结合状态分布。这种研究和分析可以推广到确定通用金属物种与通用蛋白质的非共价结合模式。
