Xiang Guanghong, Tong Changlun, Lin Haizhuan
Institute of Environmental Science, Zhejiang University, Hangzhou 310029, China.
J Fluoresc. 2007 Sep;17(5):512-21. doi: 10.1007/s10895-007-0203-3. Epub 2007 Jul 11.
The interactions of 2-nitroaniline (2-NA), 3-nitroaniline (3-NA) and 4-nitroaniline (4-NA) with bovine serum albumin (BSA) have been investigated by means of fluorescence spectrometry, synchronous fluorescence spectrometry and UV absorption spectrometry under the simulative physiological conditions. Association constants (K(A)) were estimated by the remarkable static quenching effect of 2-NA, 3-NA and 4-NA to the intrinsic fluorescence of BSA, and thermodynamic parameters such as enthalpy change (DeltaH) and entropy change (DeltaS) were calculated according to van't Hoff equation. The results show that hydrophobic force plays a main role in the interaction of nitroanilines to BSA, nitroanilines have high affinity to BSA and the affinity order is as follows: 4-NA > 2-NA > 3-NA. On the basis of this study, it is found that percents of the binding of nitroanilines to BSA are almost no relative to the concentrations of nitroanilines, and correlation between K(A) and logK (ow) is disclosed. In the meantime, relationships between the combination of nitroanilines with BSA and toxicological implications were also discussed. In addition, synchronous fluorescence method was used to study the interaction mechanisms between nitroanilines and BSA, and energy transfer distances from BSA to nitroanilines were estimated based on the Förster's non-radiation energy transfer theory. The results suggest that the binding site for nitroanilines on BSA is close to the sub-domain IIA where Trp 214 is located.
在模拟生理条件下，通过荧光光谱法、同步荧光光谱法和紫外吸收光谱法研究了2-硝基苯胺（2-NA）、3-硝基苯胺（3-NA）和4-硝基苯胺（4-NA）与牛血清白蛋白（BSA）的相互作用。根据2-NA、3-NA和4-NA对BSA固有荧光的显著静态猝灭效应估算了结合常数（K(A)），并根据范特霍夫方程计算了诸如焓变（DeltaH）和熵变（DeltaS）等热力学参数。结果表明，疏水作用力在硝基苯胺与BSA的相互作用中起主要作用，硝基苯胺对BSA具有高亲和力，且亲和力顺序如下：4-NA > 2-NA > 3-NA。基于该研究发现，硝基苯胺与BSA的结合百分比几乎与硝基苯胺的浓度无关，并揭示了K(A)与logK(ow)之间的相关性。同时，还讨论了硝基苯胺与BSA的结合与毒理学意义之间的关系。此外，采用同步荧光法研究了硝基苯胺与BSA之间的相互作用机制，并基于福斯特非辐射能量转移理论估算了从BSA到硝基苯胺的能量转移距离。结果表明，硝基苯胺在BSA上的结合位点靠近色氨酸214所在的亚结构域IIA。
