高良姜素与牛血清白蛋白作用的光谱研究

摘要

采用荧光猝灭、同步荧光、三维荧光和圆二色谱,研究高良姜素与牛血清白蛋白(BSA)之间的相互作用.结果表明:高良姜素对BSA有较强的荧光猝灭作用,且为静态猝灭,并计算出不同温度下二者的结合常数(K)与结合位点数(n)分别为9.33×106 L/mol、1.17(290.15 K),2.34×106 L/mol、1.09(296.15 K),4.57×105 L/mol、1.01(303.15 K),1.02×105 L/mol、0.99(310.15 K).由热力学参数确定它们之间的作用力主要是氢键和范德华力,利用竞争结合实验推断高良姜素的结合位点为BSA疏水空腔的Site Ⅰ.同步荧光、三维荧光和圆二色谱显示高良姜素与BSA作用时更靠近色氨酸残基,使其周围的疏水性减弱,而对蛋白α-螺旋结构影响较小.%The interaction between galangin and bovine serum albumin (BSA) was studied by fluorescence quenching,synchronous fluorescence,three-dimensional fluorescence and circular dichroism spectra.The results suggested that galangin had a strong ability to quench the BSA fluorescence in a static mode.The binding constants (Ka) and site numbers (n) obtained at different temperatures were 9.33 × 106 L/mol,1.17 (290.15 K);2.34 × 106 L/mol,1.09 (296.15 K);4.57 × 105 L/mol,1.01 (303.15 K);1.02 × 105 L/mol,0.99 (310.15 K),respectively.According to the thermodynamic parameters,hydrogen bond and van Edward force played dominant roles in the interaction between galangin and BSA.While the competitive binding analysis showed that the binding location of galangin to BSA is the Site I of the hydrophobic pocket.Spectra of synchronous fluorescence,three-dimensional fluorescence and circular dichroism revealed that galangin interacted with tryptophan residues in BSA more strongly than with tyrosine residues,and the vicinity of tryptophan residues was less hydrophobic.However,conformational changes of α-helix were slighter.