In vitro Analysis of the Interaction between Human Serum Albumin and Semi-Synthetic Clerodanes

The interaction between HSA and two semi-synthetic potential anti-cancer agents derived from trans -dehydrocrotonin-methyl-hydrazone (MHDCTN) and phenyl-hydrazone (PHDCTN) was evaluated under physiological conditions at 296, 303 and 310 K by multi-spectroscopic techniques and molecular docking calculations. Steady state fluorescence quenching indicated a ground state association (static quenching) for both samples; however, the quenching induced by PHDCTN was not essentially static and can be accompanied by a dynamic quenching mechanism. The binding is strong (modified Stern-Volmer binding constant (Ka) ca. 105 M-1), causing a very weak perturbation on the secondary structure of the protein and there is just one main binding site for both samples (Sudlow’s site I). Molecular docking results suggested hydrogen bonding and hydrophobic interactions as the main binding forces for both samples.

本研究采用多光谱技术与分子对接计算方法，在296、303及310 K的生理条件下，探究了人血清白蛋白（Human Serum Albumin, HSA）与两种分别衍生自反式去氢巴豆宁-甲基腙（trans-dehydrocrotonin-methyl-hydrazone, MHDCTN）和苯腙（phenyl-hydrazone, PHDCTN）的半合成潜在抗癌候选药物之间的相互作用。稳态荧光猝灭实验表明，两种样品均存在基态缔合过程（即静态猝灭）；但PHDCTN诱导的猝灭并非完全静态，还伴随动态猝灭机制。二者结合作用较强，修正的斯特恩-沃尔默（Stern-Volmer）结合常数（Ka）约为10⁵ M⁻¹，对蛋白质二级结构的扰动极弱，且两种样品均仅存在一个主要结合位点——萨德洛位点I（Sudlow’s site I）。分子对接结果显示，氢键与疏水相互作用是两种样品的主要结合驱动力。