Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad, Iran.
Department of Medical Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
Luminescence. 2022 Feb;37(2):310-322. doi: 10.1002/bio.4173. Epub 2021 Dec 29.
With advances in new drug therapies, it is essential to understand the interactions between drugs and target molecules. In this study, we applied multiple spectroscopic techniques including absorbance, fluorescence, circular dichroism spectroscopy, viscosity, thermal melting, calorimetric, and molecular dynamics (MD) simulation to study the interaction between 2-Ethyl-5-(4-methylphenyl) pyramido pyrazole ophthalazine trione (PPF) and calf thymus DNA (ct DNA) in the absence or presence of histone H1. PPF exhibits a high binding affinity towards ct DNA in binary and ternary systems. In addition, the result for the binding constant was observed within the range 10 M achieved through fluorescence quenching data, while the values for enthalpy and entropy changes for ct DNA-PPF and (ct DNA-H1) PPF complexes were measured to be -72.54 kJ.mol , -161.14 J.mol K , -85.34 kJ.mol , and -19.023 J.mol K , respectively. Furthermore, in accordance with circular dichroism spectra, the inducement of ct DNA structural changes was observed during binding of PPF and H1 in binary and ternary system forms. The essential roles of hydrogen bonding and van der Waals forces throughout the interaction were suggested using thermodynamic parameters. According to the obtained data, the interaction mode of ct DNA-PPF and (ct DNA-H1) PPF complexes was intercalation binding. Suggested by the MD simulation study, the ct DNA-H1 complex caused a reduction in the stability of the DNA structure in the presence or absence of ligand, which demonstrated that PPF as an intercalating agent can further distort the structure. The information achieved from this study will be very helpful in understanding the effects of PPF on the conformational state of ct DNA in the absence or presence of the H1 molecule, which seems to be quite significant for clarifying the mechanisms of action and its pharmacokinetics.
随着新药治疗的进步，了解药物与靶分子之间的相互作用至关重要。在这项研究中，我们应用了多种光谱技术，包括吸收光谱、荧光光谱、圆二色性光谱、粘度、热熔融、量热法和分子动力学（MD）模拟，来研究 2-乙基-5-(4-甲基苯基)吡唑并嘧啶并哒嗪酮（PPF）与小牛胸腺 DNA（ct DNA）在没有或存在组蛋白 H1 时的相互作用。PPF 在二元和三元体系中对 ct DNA 表现出高的结合亲和力。此外，通过荧光猝灭数据观察到结合常数的结果在 10 M 的范围内，而 ct DNA-PPF 和（ct DNA-H1）PPF 复合物的焓和熵变化值分别测量为-72.54 kJ/mol ，-161.14 J/mol K ，-85.34 kJ/mol 和-19.023 J/mol K 。此外，根据圆二色光谱，在 PPF 和 H1 在二元和三元体系形式结合时，观察到 ct DNA 结构变化的诱导。通过热力学参数表明，氢键和范德华力在整个相互作用中起着重要作用。根据获得的数据，ct DNA-PPF 和（ct DNA-H1）PPF 复合物的相互作用模式为嵌入结合。通过 MD 模拟研究表明，ct DNA-H1 复合物在存在或不存在配体的情况下降低了 DNA 结构的稳定性，这表明 PPF 作为嵌入剂可以进一步扭曲结构。从这项研究中获得的信息将非常有助于理解 PPF 在没有或存在 H1 分子的情况下对 ct DNA 构象状态的影响，这似乎对于阐明作用机制及其药代动力学非常重要。
