荧光法研究3种黄酮化合物与牛血清白蛋白的结合作用

运用荧光光谱法研究了生理酸度条件下（pH=7.4）3种黄酮化合物白杨素、芹菜素和桑色素与牛血清白蛋白（BSA）的结合作用。结果表明,3种黄酮化合物均能与BSA形成基态复合物导致BSA内源荧光猝灭,猝灭机理为静态猝灭。结合常数K（芹菜素）〉K（白杨素）〉K（桑色素）,结合位点数近似等于1,白杨素与BSA之间以疏水作用为主,而芹菜素、桑色素与BSA之间的作用力主要是氢键和范德华力。黄酮分子结构中羟基位置及个数影响其与BSA间的结合作用,C4＇-OH对结合有促进作用,而C3-OH的取代则导致作用力减弱。由Frster非辐射能量转移理论,计算出3种黄酮化合物在蛋白质中的结合位置与212位色氨酸残基间的距离分别为2.44 nm（白杨素）、3.34 nm（芹菜素）和3.31 nm（桑色素）。

Studies on the Interaction between Three Flavonoid Compounds and Bovine Serum Albumin by Fluorescence Spectroscopy

The interaction between three flavonoid compounds（chrysin,apigenin and morin） and bovine serum albumin（BSA） under physiological condition（pH=7.4） was investigated with the use of fluorescence spectroscopy.The experimental results showed that there was a strong fluorescence quenching reaction of flavonoid to BSA.The main quenching mechanism of fluorescence of BSA by flavonoid was a static quenching by forming the flavone-BSA complex.There existed binding constants K（apigenin）K（chrysin）K（morin）,number of binding sites was about 1.The interaction between chrysin and BSA was driven mainly by hydrophobic force,whereas hydrogen bonds and van der Waals forces coexisted in apigenin-BSA and morin-BSA systems,which indicated that interaction of the flavone with BSA was affected by the different structure of flavonoid compounds.The results showed that C4＇-OH could enhance the binding affinity obviously,but C3-OH weakened largely the affinity.The binding locality away from tryptophan residue-212 in BSA was calculated to be 2.44 nm（chrysin）,3.44 nm（apigenin） and 3.31 nm（morin）,respectively,based on the Frster＇s theory of non-radiation energy transfer.