维生素C、维生素B_2和葡萄糖对杜鹃素与BSA结合的扰动

Interference of VC、VB_2 and glucose in binding process of farrerol-bovine serum album

在生理酸度条件下(pH 7.4),采用荧光、紫外、红外及圆二色谱等方法,研究了3种典型营养物质维生素C(VC)、维生素B2(VB2)和葡萄糖(Glu)分别对植物活性成分杜鹃素与牛血清白蛋白(BSA)结合的扰动。计算了3种营养物质分别存在时BSA-杜鹃素体系的猝灭常数(Ksv)、结合常数(Ka)、结合位点数(n)及结合距离(r)等参数,总结了3种营养物质可能的扰动方式。结果显示,25℃时,在VC存在下,BSA-杜鹃素体系的Ksv减小46.2%,Ka减小17.1%,n减少1.8%,r增大2.9%;VB2存在下,Ksv减小57.0%,Ka增加34.8%,n减少8.1%,r增大1.9%;Glu存在使体系的Ksv减小31.7%,Ka减小14.7%,n减少9.5%,r略增1.3%。VC存在下,BSA-杜鹃素体系的作用力类型由静电引力变为以疏水作用为主,而VB2或Glu参与下,作用力类型转变为氢键和范德华力。VB2能够增加BSA-杜鹃素体系的稳定性,而VC和Glu则降低其稳定性。VC、VB2、Glu与BSA结合导致BSA分子构象变化是该营养物质扰动BSA-杜鹃素结合的共通方式和主要方式。

The effect of 3 kinds of coexisting nutrients,VC,VB2 and glucose on the binding between farrerol and bovine serum albumin（BSA） in physiological buffer（pH=7.4） was investigated by using different spectroscopic techniques viz.,fluorescence,UV-vis absorption,fourier transform infrared（FT-IR） and circular dichroism（CD） spectroscopy.The binding parameters such as the Stern-Volmer dynamic quenching constant（Ksv）、binding constant（Ka）,the number of binding sites（n） and binding distance（r） were obtained.The detailed interferential quomodo of the nutrients were concluded.The values of Ksv,Ka and n of the BSA-farrerol system were decreased by 46.2%,17.1% and 1.8%,respectively,while r was increased 2.9% in the presence of VC at 298K.VB2 decreased Ksv by 57.0%,increased Ka by 34.8%,decreased n by 8.1% and increased r 1.9%.Glucose decreased Ksv,Ka and n by 31.7%,14.7% and 9.5%,respectively,and increased r by 1.3%.With VC,the main driving force in BSA-farrerol binding process was changed from electrostatic forces to hydrophobic interaction.Whereas,the type of main driving force was changed to hydrogen bond and van der Waals forces in the presence of VB2 and glucose.It was proved that VB2 could increase the stability of BSA-farrerol complex,while VC and glucose could reduce the stability of drug-BSA.CD results showed that BSA molecular conformational change induced by the nutrients-BSA binding was a common interferential and main quomodo of the coexisting nutrients.