摘要
在298.15 K下,应用等温滴定量热法和圆二色谱法研究了氧化苦参碱(OMT)与牛血清白蛋白(BSA)的相互作用,并讨论了二者结合过程热力学性质的改变.研究结果表明,BSA大分子上存在可结合OMT分子的两类位点.OMT分子与第一类位点相结合时,结合过程的平衡常数、标准摩尔焓变和标准摩尔吉布斯自由能变分别为K1=(2.14±0.31)×105,ΔH1=(-1.07±0.50)kJ·mol-1,ΔG1=(-30.4±0.4)kJ·mol-1,最大可结合位点数为N1=(10.0±0.2),该过程是以熵驱动为主的焓熵协同驱动过程.OMT分子与第二类位点相结合时,K2=(6.84±0.32)×103,ΔH2=(1.91±0.03)kJ·mol-1,ΔG2=(-21.9±0.4)kJ·mol-1,N2=(25.0±0.3),该过程是熵驱动过程.圆二色谱测试结果表明,两类结合过程中,OMT与BSA的相互作用均导致了蛋白质二级结构构象及不同结构单元相对含量的变化.
The interaction of oxymatrine （OMT） with bovine serum albumin （BSA） was investigated by using nano-watt-scale isothermal titration calorimetry and circular dichroism （CD） spectrometry at 298.15 K. Changes of thermodynamic functions corresponding to the binding process were obtained and discussed. The results indicated that there were two classes of binding sites between BSA and OMT molecules. When the drug molecule binding to the first class of sites, the binding constant （K1^θ）, the standard changes of enthalpy （△H^1θ） and Gibbs free energy （△G^1θ） are （2.14±0.31）×10^5, （-1.07±0.50）kJ·mol^-1 and （-30.4±0.4）kJ·mol^-1, respectively. The possible largest number of binding site （N1） is （10.0 ± 0.2）. This type of binding is an enthalpy-entropy synergically driven process. On the second class of binding sites, the binding constant K2^θ （ 2 ）, the standard changes of enthalpy （△H2^θ） and Gibbs free energy （△G2^θ） are （6.84±0.32）×10^3, （1.91±0.03）kJ·mol^-1 and （-21.9±0.4）kJ·mol^-1, respectively. The possible largest number of binding site （N2） is （25.0±0.3）. This type of binding is an entropy driven process. The CD spectra showed that both the conformation and the relative contents of secondary structure units of BSA were changed by the two types of binding processes.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2009年第18期2155-2158,共4页
Acta Chimica Sinica
基金
国家自然科学基金(No20773059)资助项目
关键词
等温滴定量热法
圆二色光谱
氧化苦参碱
牛血清白蛋白
isothermal titration calorimetry
circular dichroism spectrometry
oxymatrine
bovine serum albumin
