补骨脂素和异补骨脂素与人免疫球蛋白的相互作用

将互为同分异构体的两种植物药活性组分补骨脂素和异补骨脂素作为研究对象, 应用荧光光谱法、紫外光谱法以及红外光谱法并结合分子对接技术对这两种香豆素类化合物与人-γ球蛋白(Human gammago-bulin, HG)的相互作用进行了比较研究. 荧光光谱法研究结果表明, 补骨脂素和异补骨脂素与蛋白之间均有较强的结合(结合常数位于0.251×10⁴～3.503×10⁴之间), 且对HG都表现为静态猝灭. 不同温度(298, 308和318 K)下两种药物与HG相互作用的结合参数均有所差别, 维持药物-蛋白质体系的作用力也不相同. 依据Förster能量转移理论, 得到补骨脂素和异补骨脂素分子与蛋白质色氨酸残基间的结合距离r值(分别为3.65和4.21 nm)都小于7 nm, 说明发生了能量转移. 利用同步荧光与红外光谱法研究了药物对蛋白质二级结构的影响. 分子对接研究结果表明, 这两种药物与蛋白有相似的结合区域和相同的结合模式.

Interaction of Psoralen or Isopsoralen with Human Immunoglobulin

The active components of plant herbs possessed analogical isomeride structure(psoralen and isopsoralen) were selected as research targets. A combination of intrinsic fluorescence, UV-Vis spectroscopy, FTIR and the molecular modeling technique has been used to characterize the binding between both coumarins and human gammagobulin(HG). The results from fluorescence spectroscopy indicated that the two drugs could interact with the protein strongly(binding constants between 0.251×104—3.503×104). The two drugs indicated the same static quenching mechanism for HG. The binding parameters for the different drug-protein systems are different under different temperatures(298, 308 and 318 K), and the binding modes were also different. The values of r are lower than 7 nm after interaction between the protein tryptophan residue and the bound psoralen or isopsoralen molecules(3.65 and 4.21 nm, respectively), which indicated the efficiency of energy transfer according to Förster theory. The secondary structure compositions of the globulin and the drugs complexs were estimated by qualitative and quantitative analysis from synchronous fluorescence spectra and FTIR experimental data.The molecular model studies revealed the analogial binding locations and identical binding mode for drug-HG systems. The similarities and differences between the results of these experiments may be related to the two isomers of the structure of psoralen and isopsoralen.