山梨酸钾与蛋白质相互作用的荧光和共振光散射光谱研究

 用荧光光谱和共振散射光谱(RLS)对山梨酸钾(PSA)与牛血清蛋白(BSA)在溶液中的相互作用进行了研究，探讨了PSA对BSA荧光和共振光散射猝灭的机理，测定了该反应的表观结合常数及结合位点数。在288和293 K时的表观结合常数分别为2.23×10³和2.74×10³ L·mol^-1，其相应的结合位点数分别为1.02和0.99。利用热力学参数确定了分子间的作用力性质，作用过程是自发的，作用力主要是电子作用力。同步荧光光谱表明相互作用对蛋白质构象有一定的影响。基于Forster非辐射能量转移理论估算了山梨酸钾与蛋白质之间的结合距离。

Interaction between Potassium Sorbate and Bovine Serum Albumin Revealed by Fluorescence and Resonance Light Scattering Spectra

The interaction between potassium sorbate (PSA) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy, resonance light-scattering (RLS) spectroscopy. The quenching mechanism was analyzed referring to PSA against the fluorescence and the resonance light scattering spectra of BSA. The apparent binding constants (K_A) between PSA and BSA were 2.23 × 10~3 L·mol~(-1) (288 K) , and 2.74 × 10~3 L·mol~(-1) (293 K) , respectively. The corresponding binding sites values (n) were 1.02 and 0.99.The changes of negative entropy change and enthalpy indicate that the interaction of PSA and BSA was driven mainly by electrostatic interactions. The binding process was a spontaneous process in which Gibbs free energy change was negative. The effect of PSA on the conformation of BSA was analyzed by synchronous fluorescence spectroscopy. Furthermore, the binding distance r =2.83 nm between PSA and BSA was obtained based on the mechanism of Forster non-radiation energy transfer.