光谱法测定伊曲康唑与牛血清和人血清白蛋白相互作用

用荧光光谱和紫外吸收光谱法, 在pH=7.4±0.1的0.1 mol·L-1磷酸缓冲溶液中, 研究了伊曲康唑与牛血清白蛋白(BSA)和人血清白蛋白(HSA)的相互作用. 实验结果表明, 伊曲康唑与牛血清白蛋白和人血清白蛋白作用的猝灭常数均随着温度的升高而降低, 伊曲康唑可以有规律地使血清白蛋白内源荧光猝灭, 其猝灭机理可认为是伊曲康唑与白蛋白形成复合物的静态猝灭. 获得了在不同温度下, 伊曲康唑与血清白蛋白作用的结合常数以及△G、△H和△S等热力学参数. 根据所得结果可推断伊曲康唑与白蛋白的作用力主要为疏水作用力, 同时, 利用荧光共振能量转移理论(FRET)计算得出了伊曲康唑与白蛋白结合位置的距离d. 而且, 利用同步荧光光谱和紫外光谱揭示了该反应中蛋白的结构和其微环境的变化.

Characterization of the Interactions between Itraconazole and Human and Bovine Serum Albumins by a Spectroscopic Method

The binding of itraconazole (ITZ), a potential antifungal, to human serumalbumin (HSA) and bovine serum albumin (BSA) were studied at the physiological acidity (pH=7.4±0.1) by fluorescence and UV-Vis spectroscopies. A decrease in the quenching constant was observed with an increase in temperature. From the fluorescence spectrum and the fluorescence intensity, we observed that ITZ strongly quenches the intrinsic fluorescence of both BSA and HSA by static quenching. Thermodynamic parameters, such as △G, △H and △S, were calculated at different temperatures, showing that electrostatic and hydrophobic interactions were mostly responsible for the binding of ITZ to serum albumin. The distance d between the donor (HAS or BSA ) and acceptor (ITZ) was obtained according to fluorescence resonance energy transfer theory (FRET). Synchronous fluorescence and UV-Vis spectroscopy clearly revealed that the microenvironment and the conformation of serumalbumins changed during the binding reaction.