摘要
本文用吸收、荧光、圆二色等光谱法研究了9-甲氧基喜树碱(9-MCPT)与BSA的相互作用。随着9-MCPT的导入,BSA的吸收光谱发生位移,BSA的荧光发生猝灭并使荧光发射峰蓝移,说明9-MCPT与BSA发生了相互作用,且其产物是复合物。298K下体系的猝灭常数、结合常数和结合位点数分别为9.550×10^4 L·mol^-1、2.589×10^4 L·mol^-1和0.8949;并且猝灭常数随温度升高而减小,表明9-MCPT以静态方式猝灭BSA的荧光、结合比为1∶1。该体系的ΔH和ΔS均为负值,分别为-5.791 KJ·mol^-1、-2.636 J·mol^-1·K^-1,说明BSA与9-MCPT的结合主要是氢键和范德华力所使,ΔG<0表明9-MCPT自发与BSA发生作用。同步荧光光谱数据显示,9-MCPT接近BSA中酪氨酸残基。位点竞争实验显示9-MCPT-BSA的结合位点处于在BSAⅡA亚域内的SiteⅠ位点上。CD光谱中BSA的α-螺旋结构比例减少、β-折叠比例增加,表明9-MCPT改变了BSA的二级结构。
The interaction between 9-methoxycamptothecin and BSA were studied by ultraviolet,fluorescence and circular dichroism spectroscopy.The shifts of UV-visible absorption spectrum,the quenches and blue shifts of the fluorescence peak of BSA with the addition of 9-MCPT indicated that 9-MCPT can react with BSA and form a 1∶1 complex.The quenching constant,binding constant and binding site number of the 9-MCPT-BSA system at 298 K were calculated to be 9.550×10^4 L·mol-1,2.589×10^4 L·mol-1 and 0.8949,respectively.The quenching constant decreases with increasing temperature,indicating that the mode of the 9-MCPT-BSA system is static quenching.The negative value ofΔH andΔS(-5.791 KJ·mol-1,-2.636 J·mol-1·K-1,respectively)of the system are been illustrated that the binding of 9-MCPT to BSA is controlled mainly hydrogen bonding and van der Waals force.Synchronous fluorescence showed that 9-MCPT was closer to the tyrosine group.The competition experiments showed that the binding site of BSA with 9-MCPT is at the Site I site in the subdomain IIA cavity.The decrease of theα-helical and the increase ofβ-sheet in CD spectrum indicated 9-MCPT changes the secondary structure of BSA.
作者
吕鉴泉
彭淑红
吕汉清
刘慧娜
朱君仪
LU Jian-quan;PENG Sun-hong;LU Han-qing;LIU Hui-na;ZHU Jun-yi(School of Chemistry and Environment,Jiaying University,Meizhou 514015,China;School of Life Science,Jiaying University,Meizhou 514015,China)
出处
《化学研究与应用》
CAS
CSCD
北大核心
2020年第7期1134-1140,共7页
Chemical Research and Application
基金
广东省省市共建项目(252B0102)资助
广东省大学生科技创新培育专项(pdjh201807,201810582121)资助。
