Kawai K, Cowger M L
Res Commun Chem Pathol Pharmacol. 1982 Mar;35(3):499-513.
The interaction of bovine serum albumin (BSA) and xanthomegnin, an uncoupler of oxidative phosphorylation was studied spectrophotometrically. BSA caused a marked red shift of the absorption maxima of xanthomegnin from 406 to 555 nm but heating the reaction mixture abolished the BSA-induced spectral change. Spectrophotometric titrations of xanthomegnin with increasing concentrations of BSA gave a molar ratio of unity for these two components with an association constant of 1.4 X 10(6) M-1. The absorption spectrum of xanthomegain was affected by pH changes of the system. The pK was found to be 8.4 and was significantly shifted to a lower pH (pH 5.4) in the presence of BSA. The BSA-induced spectral change was abolished by sodium dodecyl-sulfate or 1 anilino-8 napthalene sulfonic acid but not by L-tryptophan. These results would suggest that the characteristic spectral changes of xanthomeginin are caused by reversible binding to a strong, hydrophobic anion binding site of BSA. In many respects the binding resembles that of bilirubin with this same protein. In the latter reaction, the red shift was much smaller than the reaction of BSA and xanthomegnin.
采用分光光度法研究了牛血清白蛋白（BSA）与氧化磷酸化解偶联剂黄天精的相互作用。BSA使黄天精的吸收峰从406nm显著红移至555nm，但加热反应混合物可消除BSA诱导的光谱变化。用浓度递增的BSA对黄天精进行分光光度滴定，得到这两种成分的摩尔比为1，缔合常数为1.4×10⁶ M⁻¹。黄天精的吸收光谱受体系pH变化的影响。发现其pK为8.4，在存在BSA的情况下显著移至较低pH（pH 5.4）。十二烷基硫酸钠或1-苯胺基-8-萘磺酸可消除BSA诱导的光谱变化，但L-色氨酸不能。这些结果表明，黄天精的特征光谱变化是由于其与BSA的强疏水性阴离子结合位点可逆结合所致。在许多方面，这种结合类似于胆红素与同一蛋白质的结合。在后者的反应中，红移比BSA与黄天精的反应小得多。
