长春新碱与牛血清白蛋白相互作用研究

利用紫外、荧光和圆二色光谱研究了不同温度下长春新碱(VCR)与牛血清白蛋白(BSA)之间的相互作用。通过荧光猝灭数据算得在 296，303和310 K时，VCR与BSA的猝灭常数K_SV分别为2.0×104，1.7×104和1.5×104 L·mol-1，结合常数K_a分别为1.5×104，9.5×103和4.9×103 L·mol-1，结合位点数分别为0.978 6，0.949 0和0.891 1，表明VCR与BSA间具有较强的结合作用，但结合能随着温度的升高而降低，是形成复合物的静态猝灭。圆二色光谱 (CD)数据表明相互作用后BSA的二级结构发生了改变：BSA的α-螺旋的含量从33.5％下降到 29.7％，β-折叠的含量从13.6％升高到18.4％。通过Van′t Hoff方程，计算出热力学常数焓变(ΔH)和熵变(ΔS) 分别为：－62.7 kJ·mol-1和－129.38 J·（mol-1·K）－１，表明氢键和范德华力在VCR与BSA结合中处于主导作用。

Study on the Interaction between Vincristine and Bovine Serum Albumin

The interaction between vincristine (VCR) and bovine serum albumin (BSA) was investigated by UV-Vis absorption, fluorescence and circular dichroism (CD) spectra at 296, 303 and 310 K, respectively. With fluorescence quenching method, the binding constants Ka were determined to be 1.5 x 10(4) L x mol(-1), 9.5 x 10(3) L x mol(-1), 4.9 x 10(3) L x mol(-1) and the number of binding site was 1 at three temperatures, respectively. The conformation of BSA was altered (CD data) with the reductions of alpha-helices from 33.5% for free BSA to 29.7%, and with increases of beta-sheet from 13.6% for free BSA to 18.4% in the presence of VCR. The thermodynamic parameters, enthalpy change (deltaH) and entropy change (deltaS), were calculated to be -62.07 kJ x mol(-1) and -129.38 J x (mol x K)(-1) respectively, according to van't Hoff equation, which indicated that hydrogen bonds and van der walls interactions played major roles in the binding process.