荧光光谱法研究盐酸赛庚啶与牛血清白蛋白的相互作用

Studies on the Interaction between Cyproheptadine Hydrochloride and Bovine Serum Albumin by Fluorescence Spectroscopy

在pH=7.40生理条件下,盐酸赛庚啶(CH)对牛血清白蛋白(BSA)的荧光强度具有明显的猝灭作用。在25mL比色管中,加入一定量的Tris-HCl缓冲溶液、BSA和CH,用水稀释至刻度,选择20、30和37℃恒温0.5h后,扫描其荧光光谱和同步荧光光谱。求得了CH-BSA的表观结合常数(KA(20℃)=0.46×105,KA(30℃)=3.14×105,KA(37℃)=1.16×105),结合位点数n≈1。由所得热力学常数确定了CH-BSA以疏水作用力为主结合。评估了共存AuNP对CH-BSA作用的影响,其结合常数降低一个数量级,结合位点数也有所降低。根据F rster偶极-偶极无辐射能量转移理论,求得了CH-BSA的结合距离(r)=5.07nm和能量转移效率E=0.0157。此外,应用紫外吸收光谱法研究了CH-BSA的作用机理。

The fluorescence intensity of bovine serum albumin(BSA)was obviously quenched by cyproheptadine hydrochloride(CH)under the physiological condition of pH=7.40.In a 25 mL colorimetric tube,a certain amount of Tris-HCl buffer solution,BSA and CH were added.The solution was diluted to the mark with water and the temperature was set at 20,30 and 37℃for 0.5 h.Then it was scanned by fluorescence and synchronous fluorescence spectrum.The apparent binding constants of CH-BSA were determined as KA(20℃)=0.46×105,KA(30℃)=3.14×105 and KA(37℃)=1.16×105,number of binding sites n≈1.The thermodynamic constants were obtained so as to determine that the major roles of binding force of CH-BSA was the hydrophobic.The effect of co-existing AuNP on CH-BSA was evaluated.The binding constant reduced by one order of magnitude and the number of binding sites was also reduced.According to the F rster dipole-dipole non-radiative energy transfer theory,the binding distance of CH-BSA was calculated(r)=5.07 nm and the energy transfer efficiency was calculated E=0.0157.In addition,the mechanism of action of CH-BSA was studied using ultraviolet absorption spectroscopy.