Zhang Ye-Zhong, Zhou Bo, Liu Yan-Xia, Zhou Chun-Xia, Ding Xin-Liang, Liu Yi
Department of Chemistry, College of Chemistry and Environmental Engineering, Yangtze University, JingZhou, Hubei 434025, People's Republic of China.
J Fluoresc. 2008 Jan;18(1):109-18. doi: 10.1007/s10895-007-0247-4. Epub 2007 Sep 25.
In this paper, the interaction between p-aminoazobenzene (PAAB) and BSA was investigated mainly by fluorescence quenching spectra, circular dichroism (CD) and three-dimensional fluorescence spectra under simulative physiological conditions. It was proved that the fluorescence quenching of BSA by PAAB was mainly a result of the formation of a PAAB-BSA complex. The modified Stern-Volmer quenching constant K(a) and the corresponding thermodynamic parameters DeltaH, DeltaG and DeltaS at different temperatures were calculated. The results indicated that van der Waals interactions and hydrogen bonds were the predominant intermolecular forces in stabilizing the complex. The distance r=4.33 nm between the donor (BSA) and acceptor (PAAB) was obtained according to Förster's non-radioactive energy transfer theory. The synchronous fluorescence, CD and three-dimensional fluorescence spectral results showed that the hydrophobicity of amino acid residues increased and the losing of alpha-helix content (from 63.57 to 51.83%) in the presence of PAAB. These revealed that the microenvironment and conformation of BSA were changed in the binding reaction.
本文主要通过荧光猝灭光谱、圆二色光谱（CD）和三维荧光光谱，在模拟生理条件下研究了对氨基偶氮苯（PAAB）与牛血清白蛋白（BSA）之间的相互作用。结果表明，PAAB对BSA的荧光猝灭主要是形成PAAB-BSA复合物的结果。计算了不同温度下修正的Stern-Volmer猝灭常数K(a)以及相应的热力学参数ΔH、ΔG和ΔS。结果表明，范德华相互作用和氢键是稳定该复合物的主要分子间作用力。根据Förster非辐射能量转移理论，得出供体（BSA）与受体（PAAB）之间的距离r = 4.33 nm。同步荧光、CD和三维荧光光谱结果表明，在PAAB存在下，氨基酸残基的疏水性增加，α-螺旋含量降低（从63.57%降至51.83%）。这些结果表明，在结合反应中BSA的微环境和构象发生了变化。
