摘要
在298.15K下,应用等温滴定量热法研究了人血清白蛋白(HSA)与两种季铵盐双子表面活性剂[(CnN)2Cl2,n=12,14]在缓冲溶液(pH=7.0)中相互作用的热力学性质.实验结果表明,HSA对这两种表面活性剂有两类结合位点,分别为结合时需要吸收热量的强结合位点和可放出热量的弱结合位点.两种表面活性剂对应的第一类结合——强结合为熵驱动过程,且该结合位点对应的结合位点数、结合常数和热力学参数差别不大.至于第二类结合——弱结合位点,由于(C14N)2Cl2疏水链过长,只有部分进入HSA的疏水空腔内,因此相应的的结合位点数和放热量减小,而熵变增加,为焓和熵共同驱动的反应.圆二色研究表明(CnN)2Cl2的加入使HSA的二级结构发生变化,这说明(CnN)2Cl2与HSA的相互作用既包含结合反应也包含(CnN)2Cl2诱导该蛋白部分结构改变的过程.
Thermodynamics of the interaction of human serum albumin （HSA） with bis-quatemary ammonium surfactants, （CnN）2Cl2 （n= 12 and 14）, in buffer solution （pH=7.0） has been investigated by isothermal titration calorimetry at 298.15 K. The results show that there are two types of binding sites on HSA for the two surfactants. One is endothermic high-affinity binding, and the other is exothermic low-affinity binding. For the two surfactants, the first type of binding, high-affinity binding is entropy driven process, and the differences of binding site number, binding constants and thermodynamic parameters are small. While as for the second binding sites, low-affinity binding sites, only portion of hydrophobic chains of （C14N）2Cl2 can penetrate into the hydrophobic cavity because its hydrophobic chains are too long, which leads to the reduction of binding site number and evolved heat as well as the increasing of entropy. The low-affinity binding of （CnN）2Cl2 to HSA is driven by a favorable entropy increasing with a less favorable enthalpy decrease. Circular dichroism （CD） spectra show that the two surfactants can change the secondary structure of HSA. These results indicate that the interaction of （CnN）2Cl2 with HSA includes contributions of the binding and the oartial change of structure of the orotein induced by the two surfactants.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2007年第2期123-128,共6页
Acta Chimica Sinica
基金
国家自然科学基金(No.20273061)资助项目.
关键词
等温滴定量热法
圆二色法
季铵盐双子表面活性剂
人血清白蛋白
isothermal titration calorimetry
circular dichroism
bis-quaternary ammonium surfactant
human serum albumin
