表没食子儿茶素没食子酸酯(EGCG)与人血清白蛋白相互作用的研究

INTERACTION OF EPIGALLOCATECHIN GALLATE WITH HUMAN SERUM ALBUMIN

在不同温度下,用荧光猝灭光谱、紫外-可见吸收光谱及分子对接的方法研究表没食子儿茶素没食子酸酯(EGCG)与人血清白蛋白(HSA)的相互作用.研究结果表明,EGCG可与HSA相互作用并使HSA发生内源性的静态荧光猝灭.利用Stern-Volmer方程处理实验数据,计算得到17和37℃下的静态猝灭常数(Kq)分别为7.153×105和7.886×105L.mol-1,结合常数(KA)分别为9.541×105和9.586×105L.mol-1,结合位点(n)为1.通过计算热力学参数,可知该EGCG与HSA的相互作用是一个吉普斯自由能降低的自发过程,且二者之间的主要作用力类型为疏水作用力.根据非辐射能量转移机制,算出HSA和EGCG间的作用距离和能量转移效率分别为3.02 nm和0.188.利用Autodock3程序进行HSA和EGCG对接计算,对接结果支持了光谱学的结论.

The interactions of EGCG （epigallocatechin gallate） with HSA （human serum albumin）were studied by fluorescence and ultra-violet spectroscopic and Autodock3 procedure. It was found that EGCG quenched the fluorescence intensity of HSA by a static quenching process, which indicated that EGCG bound to one binding site in HSA, resulting in a ground state complex. The molecular quenching constants （Kq） were 7. 153×10^5 and 7. 886×10^5 L.mol^-1, and the binding constants （Ka） were 9. 541X10s and 9. 586× 10^5 L. mol^-1 at 17 and 37℃, respectively. Thermodynamic parameters calculated from van＇t Hoff equation suggest that the interaction was spontaneous and mainly by an initial hydrophobic association. Based on the theory of Forster nonradiative energy transfer, the distance between the ligand （HSA） and receptor （EGCG） and efficiency of energy transfer were calculated to be 3.02 nm and 0. 188, respectively. Data obtained by spectroscopic analysis were supported by data from Autodock study.