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人血清白蛋白多种结合位点的存在使其成为许多药物可能的结合靶点.土贝母皂苷具有广泛的生理和药理活性,它与蛋白质相互作用机制的研究对于深入了解其药理药效具有重要的意义.采用荧光光谱法研究了土贝母皂苷II(TBMSⅡ)与人血清白蛋白(HSA)之间的相互作用,根据Stern-Volmer荧光淬灭方程计算得293,298,303,308 K时TBMSⅡ与HSA相互作用的结合常数分别为1.002×105,0.701×105,0.514×105,0.411×105 L?mol-1.由实验计算出热力学参数焓变?H为-44.829 kJ?mol-1,熵变?S为-57.497 J?mol-1?K-1,表明分子间的氢键及疏水作用是TBMSⅡ-HSA复合物的主要作用力,结合位点位于HSA的亚结构ⅡA,这与分子模拟方法的结果相一致.依据能量转移原理求得TBMSⅡ与HSA间的距离为4.95 nm;三维、同步荧光光谱及圆二色谱的结果表明TBMSⅡ的加入使HSA构象发生变化,α-螺旋结构有所下降.
The existence of a variety of binding sites for human serum albumin makes it a potential target for many drugs.Dubulin has a wide range of physiological and pharmacological activities, and its interaction with protein mechanisms for further understanding of its pharmacological effects The interaction between TBMSⅡ and human serum albumin (HSA) was studied by fluorescence spectroscopy and the interaction between TBMSⅡ and HSA was calculated according to Stern-Volmer fluorescence quenching equation at 293,298,303,308 K The binding constants were 1.002 × 105, 0.701 × 105, 0.514 × 105 and 0.411 × 105 L mol-1, respectively. The enthalpy change of the thermodynamic parameter was calculated to be -44.829 kJ? Mol-1 and the entropy change? S was -57.497 J mol-1K-1, indicating that the intermolecular hydrogen bonding and hydrophobic interaction are the main forces of TBMSⅡ-HSA complex, the binding site is located in the sub-structure ⅡA HSA, which is consistent with the results of molecular modeling method According to the principle of energy transfer, the distance between TBMSⅡ and HSA was 4.95 nm. The results of three-dimensional, simultaneous fluorescence spectroscopy and circular dichroism showed that the addition of TBMSⅡ changed the conformation of HSA and the α-helix structure decreased.