Ehwald R, Ballerstädt R, Dautzenberg H
Institute of Biology, Humboldt University of Berlin, Germany.
Anal Biochem. 1996 Feb 1;234(1):1-8. doi: 10.1006/abio.1996.0040.
Affinity ligands and/or affinity receptors may be quantified by a viscosimetric assay which can be carried out with a simple technique and has the potential of broad applications. The viscosimetric affinity assay is based on the high contribution of affinity bonds to the viscosity of an aqueous dispersion of a hydrocolloid that is bearing affinity ligands. In dispersions of such sensitive hydrocolloids at a concentration above the overlapping point, agglutination is not possible and the modulation of viscosity by the formation or dissociation of intercolloidal affinity bonds may be several orders of magnitude larger than the basic viscosity measurable in the absence of intercolloidal affinity bonds. If dispersions (30 g liter-1) of branched dextran with high molecular weight were used as reagent for concanavalin A (Con A), the Con A concentration necessary for a significant rise in viscosity was decreased with increasing colloid size. The viscosity of dispersions containing both a ligand-bearing high-molecular-weight dextran and an appropriate polyvalent receptor protein (lectin or antibody) showed a dependence on the concentration of free ligands (sugars or insulin) according to the law of mass action. In this competitive mode the viscosimetric affinity assay seems to be well adaptable to many analytical problems.
亲和配体和/或亲和受体可以通过粘度测定法进行定量，该方法操作简单，具有广泛的应用潜力。粘度亲和测定法基于亲和键对负载亲和配体的水胶体水分散体粘度的显著贡献。在高于重叠点浓度的此类敏感水胶体分散体中，不可能发生凝集，并且胶体间亲和键的形成或解离对粘度的调节可能比在不存在胶体间亲和键时可测量的基本粘度大几个数量级。如果使用高分子量支链葡聚糖的分散体（30 g·L⁻¹）作为伴刀豆球蛋白A（Con A）的试剂，随着胶体尺寸的增加，粘度显著升高所需的Con A浓度会降低。含有负载配体的高分子量葡聚糖和合适的多价受体蛋白（凝集素或抗体）的分散体的粘度根据质量作用定律显示出对游离配体（糖或胰岛素）浓度的依赖性。在这种竞争模式下，粘度亲和测定法似乎非常适用于许多分析问题。
