Nakamaru Y, Sato C
Biological Institute, Graduate School of Science, Tohoku University, Sendai, Japan.
Biochim Biophys Acta. 1997 Sep 5;1341(2):207-16. doi: 10.1016/s0167-4838(97)00081-2.
The interaction of bromocresol purple (BCP) anions with bovine serum albumin (BSA) was investigated by principal factor analysis method, and reaction model, the number of molecular species and spectra of each component present in the reaction mixture were determined. The number of molecular species concerning the absorption intensity was three, including free BCP anion. Most part of the spectral change could be explained by the monomer binding of bromocresol purple anion (D) to serum albumin (P), a simple one step equilibrium, P + D = PD. A second type of association of BCP anions with serum albumin was also present, though in a small amount. Of six models tested which consisted of three or four molecular species, the sequential two step reaction model, P = PD = PD2, was the best model to explain the spectral data, and an existence of BCP anions as a dimer on the serum albumin was demonstrated. The dissociation constants were estimated at K1 = 1.6 x 10(-6) M for the first step and K2 = 1.2 x 10(-5) M for the second step.
采用主因子分析法研究了溴甲酚紫（BCP）阴离子与牛血清白蛋白（BSA）的相互作用，确定了反应模型、反应混合物中各组分的分子种类数和光谱。与吸收强度有关的分子种类数为三种，包括游离的BCP阴离子。光谱变化的大部分可以用溴甲酚紫阴离子（D）与血清白蛋白（P）的单体结合来解释，这是一个简单的一步平衡反应，即P + D = PD。虽然含量较少，但也存在BCP阴离子与血清白蛋白的第二种结合类型。在测试的由三种或四种分子种类组成的六种模型中，顺序两步反应模型P = PD = PD2是解释光谱数据的最佳模型，证明了血清白蛋白上存在二聚体形式的BCP阴离子。第一步的解离常数估计为K1 = 1.6 x 10(-6) M，第二步的解离常数估计为K2 = 1.2 x 10(-5) M。
