Cao Hongguang, Yi Yanli
College of Land and Environment, Shenyang Agricultural University, Shenyang, 110866, China.
Biometals. 2017 Aug;30(4):529-539. doi: 10.1007/s10534-017-0022-1. Epub 2017 May 18.
The interaction between two chromates [sodium chromate (NaCrO) and potassium chromate KCrO)] and bovine serum albumin (BSA) in physiological buffer (pH 7.4) was investigated by the fluorescence quenching technique. The results of fluorescence titration revealed that two chromates could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The apparent binding constants K and number of binding sites n of chromate with BSA were obtained by the fluorescence quenching method. The thermodynamic parameters enthalpy change (ΔH), entropy change (ΔS) were negative, indicating that the interaction of two chromates with BSA was driven mainly by van der Waals forces and hydrogen bonds. The process of binding was a spontaneous process in which Gibbs free energy change was negative. The distance r between donor (BSA) and acceptor (chromate) was calculated based on Forster's non-radiative energy transfer theory. The results of UV-Vis absorption, synchronous fluorescence, three-dimensional fluorescence and circular dichroism (CD) spectra showed that two chromates induced conformational changes of BSA.
采用荧光猝灭技术研究了两种铬酸盐[铬酸钠（NaCrO）和铬酸钾（KCrO）]与生理缓冲液（pH 7.4）中牛血清白蛋白（BSA）之间的相互作用。荧光滴定结果表明，两种铬酸盐可通过静态猝灭过程强烈猝灭BSA的固有荧光。通过荧光猝灭法获得了铬酸盐与BSA的表观结合常数K和结合位点数n。热力学参数焓变（ΔH）、熵变（ΔS）均为负值，表明两种铬酸盐与BSA的相互作用主要由范德华力和氢键驱动。结合过程是一个吉布斯自由能变化为负的自发过程。基于福斯特非辐射能量转移理论计算了供体（BSA）与受体（铬酸盐）之间的距离r。紫外可见吸收光谱、同步荧光光谱、三维荧光光谱和圆二色性（CD）光谱结果表明，两种铬酸盐诱导了BSA的构象变化。
