5-氟尿嘧啶与牛血清白蛋白的相互作用

根据合理的假设和Langmuir结合理论, 在298.15 K下, 以等温滴定微量热(ITC)实验数据为依据, 应用非线性最小方差拟合方法确定了抗肿瘤药物配5-氟尿嘧啶(5-FU)与牛血清白蛋白(BSA)相互作用的热力学性质的改变. 研究结果表明, 牛血清白蛋白(BSA)与5-氟尿嘧啶相互作用存在两类结合位点. 第一类结合, N=(54.0 0.3), ⊿H⁰=(30.0±0.4) kJ·mol^-1 (吸热), ⊿S⁰=(196.0±2.6) J·mol-1·K-1(熵增), ⊿G⁰=(-28.4±0.3) kJ·mol^-1; 第二类结合, N=(77.0±0.4), ⊿H⁰=(-20.0±0.4) kJ·mol^-1 (放热), ⊿S⁰=(28.6±0.3) J·mol^-1·K^-1 (熵增), ⊿G⁰=(-28.5±0.2) kJ·mol^-1. 结合体系的圆二色谱(CD)分析结果说明, 抗肿瘤药物5-氟尿嘧啶与BSA的相互作用诱导蛋白质(BSA)二级结构单元的相对含量发生了一定程度的变化.

Interactions between 5-fluorouracil and Bovine Serum Albumin

From reasonable suppositions on binding process and Langmuir’s binding theory, the interactions between 5-fluorouracil (5-FU) and bovine serumalbumin (BSA) were investigated by the isothermal titration calorimetry (ITC) and the circular dichroism (CD) spectrometry at 298.15 K. The results showed that there were two classes of binding sites on a protein (BSA) molecule for the 5-fluorouracil. For the first class of binding, N=(54.0±0.3), ⊿H⁰=(30.0±0.4) kJ·mol^-1 (endothermal), ⊿S⁰=(196.0±2.6) J·mol-1·K^-1 (entropy increasing), ⊿G⁰=(-28.4±0.3) kJ·mol^-1; for the second class of binding, N=(77.0±0.4), ⊿H⁰=(-20.0±0.4) kJ·mol^-1 (exothermal), ⊿S⁰=(28.6±0.3) J·mol^-1·K^-1 (entropy increasing), ⊿G⁰=(-28.5±0.2) kJ·mol ^-1. The interactions between 5-fluorouracil and BSA induced the relative contents of secondary structure units of protein (BSA) to change in two classes of binding processes.