Zhang Ye-Zhong, Zhang Xiao-Ping, Hou Han-Na, Dai Jie, Liu Yi
Department of Chemistry, College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou, Hubei, People's Republic of China.
Biol Trace Elem Res. 2008 Mar;121(3):276-87. doi: 10.1007/s12011-007-8045-z. Epub 2007 Oct 25.
In this work, the interaction between Cu(phen)(2+)(3) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy combined with UV-vis absorption and circular dichroism (CD) spectroscopic techniques under physiological conditions. The fluorescence data proved that the fluorescence quenching of BSA by Cu(phen)(2+)(3) was the result of the Cu(phen)(2+)(3) -BSA complex formation. The binding constants (K (a)) between Cu(phen)(2+)(3) and BSA at four different temperatures were calculated according to the modified Stern-Volmer equation. The enthalpy change (DeltaH) and entropy change (DeltaS) were calculated to be 10.74 kJ mol(-1) and 54.35 J mol(-1) K(-1), respectively, which indicated that electrostatic interactions played a major role in the formation of Cu(phen)(2+)(3) -BSA complex. The distance r between the donor (BSA) and acceptor[Cu(phen)(2+)(3)] was obtained to be 3.55 nm based on Förster's energy transfer theory. The synchronous fluorescence and CD spectroscopy results showed that the polarity of the residues increased and the lost of the alpha-helix content of BSA (from 59.84 to 53.70%). These indicated that the microenvironment and conformation of BSA were changed in the presence of Cu(phen)(2+)(3).
在本研究中，采用荧光光谱结合紫外可见吸收光谱和圆二色（CD）光谱技术，在生理条件下研究了Cu(phen)(2+)(3)与牛血清白蛋白（BSA）之间的相互作用。荧光数据表明，Cu(phen)(2+)(3)对BSA的荧光猝灭是形成Cu(phen)(2+)(3)-BSA复合物的结果。根据修正的Stern-Volmer方程计算了四个不同温度下Cu(phen)(2+)(3)与BSA之间的结合常数（Ka）。计算得到的焓变（ΔH）和熵变（ΔS）分别为10.74 kJ mol(-1)和54.35 J mol(-1) K(-1)，这表明静电相互作用在Cu(phen)(2+)(3)-BSA复合物的形成中起主要作用。基于Förster能量转移理论，供体（BSA）与受体[Cu(phen)(2+)(3)]之间的距离r为3.55 nm。同步荧光光谱和CD光谱结果表明，BSA残基的极性增加，α-螺旋含量降低（从59.84%降至53.70%）。这些结果表明，在Cu(phen)(2+)(3)存在下，BSA的微环境和构象发生了变化。
