Kragh-Hansen U
Biochem J. 1985 Feb 1;225(3):629-38. doi: 10.1042/bj2250629.
Binding of warfarin, digitoxin, diazepam, salicylate and Phenol Red, individually or in different pair combinations, to defatted human serum albumin at ligand/protein molar ratios less than 1:1 was studied at pH 7.0. The binding was determined by ultrafiltration. Some of the experiments were repeated with the use of equilibrium dialysis in order to strengthen the results. Irrespective of the method used, all ligands bind to one high-affinity binding site with an association constant in the range 10(4)-10(6) M-1. High-affinity binding of the following pair of ligands took place independently: warfarin-Phenol Red, warfarin-diazepam, warfarin-digitoxin and digitoxin-diazepam. Simultaneous binding of warfarin and salicylate led to a mutual decrease in binding of one another, as did simultaneous binding of digitoxin and Phenol Red. Both effects could be accounted for by a coupling constant. The coupling constant is the factor by which the primary association constants are affected; in these examples of anti-co-operativity the factor has a value between 0 and 1. In the first example it was calculated to be 0.8 and in the latter 0.5. Finally, digitoxin and salicylate were found to compete for a common high-affinity binding site. The present findings support the proposal of four separate primary binding sites for warfarin, digitoxin (and salicylate), diazepam and Phenol Red. An attempt to correlate this partial binding model for serum albumin with other models in the literature is made.
在pH 7.0条件下，研究了华法林、洋地黄毒苷、地西泮、水杨酸盐和酚红单独或不同组合在配体/蛋白质摩尔比小于1:1时与脱脂人血清白蛋白的结合情况。通过超滤测定结合情况。为了强化结果，部分实验采用平衡透析重复进行。无论使用何种方法，所有配体均与一个高亲和力结合位点结合，缔合常数在10⁴ - 10⁶ M⁻¹范围内。以下几对配体的高亲和力结合是独立发生的：华法林 - 酚红、华法林 - 地西泮、华法林 - 洋地黄毒苷和洋地黄毒苷 - 地西泮。华法林和水杨酸盐的同时结合导致彼此结合相互减少，洋地黄毒苷和酚红的同时结合也是如此。这两种效应都可以用偶联常数来解释。偶联常数是影响一级缔合常数的因子；在这些负协同性的例子中，该因子的值在0到1之间。在第一个例子中计算得出为0.8，在第二个例子中为0.5。最后，发现洋地黄毒苷和水杨酸盐竞争一个共同的高亲和力结合位点。目前的研究结果支持了关于华法林、洋地黄毒苷（和水杨酸盐）、地西泮和酚红有四个独立的一级结合位点的提议。本文尝试将血清白蛋白的这种部分结合模型与文献中的其他模型进行关联。
