柚皮素、柚皮苷与溶菌酶相互作用的荧光光谱法研究

应用荧光光谱法研究了50%甲醇/水体系中柚皮素、柚皮苷与溶菌酶分子间的结合反应. 以Lineweaver-Burk双倒数方程和能量传递原理分别计算了两者与溶菌酶反应的结合常数(K)和结合距离(r): K_柚皮素^{25 ℃}＝4.00×10⁴, K_柚皮苷^{25 ℃}＝3.48×10⁴; r_柚皮素＝3.21 nm, r_柚皮苷＝3.30 nm, 以及由热力学参数的计算判断了两种分子与溶菌酶之间的作用力类型. 结果表明: 柚皮素、柚皮苷均能与溶菌酶以疏水作用相结合形成非共价化合物, 从而导致溶菌酶内在荧光的静态猝灭; 相对柚皮素, 柚皮苷与溶菌酶的结合距离增大, 作用强度减弱, 表明黄酮分子上多糖的取代不利于黄酮分子与蛋白之间的亲和作用. 根据Haslam等提出的多酚-蛋白质反应模型, 从分子水平初步探讨了糖取代对黄酮分子与蛋白相互作用减弱的原因.

Studies on the Interaction of Lysozyme with Naringein and Naringin by Fluorescence Spectroscopy

The interactions between lysozyme (Lys) and naringein or naringin were studied by fluorescence spectroscopy under 50% CH₃OH/water circumstance. The binding constants and bind distance of naringein- Lys and naringin-Lys were calculated according to Lineweaver-Burk equation and Föster’ energy transfer theory, which were shown as K_Naringein^{25 ℃}＝4.00×10⁴, r_Naringein＝3.21 nm and K_Naringin^{25 ℃}＝3.48×10⁴, r_Naringin＝3.30 nm, respectively. The results showed that both of them could form non-covalent compounds with Lys mainly through hydrophobic interaction force. Relative to naringein, the binding affinity of naringin to Lys decreased obviously. These suggested that the sugar substitution in the structure of flavonoid is not helpful to the binding of flavonoid-protein. According to the polyphen-protein interaction mode presented by Haslam, the reason resulted in weaker bonding affinity of naringin to Lys was analysed in the level of molecule.