Stigter D, Dill K A
Department of Pharmaceutical Chemistry, University of California, San Francisco 94143, USA.
Biophys J. 1996 Oct;71(4):2064-74. doi: 10.1016/S0006-3495(96)79405-5.
Ionic ligands can bind to polyelectrolytes such as DNA or charged polysaccharides. We develop a Poisson-Boltzmann treatment to compute binding constants as a function of ligand charge and salt concentration in the limit of low ligand concentration. For flexible chain ligands, such as oligopeptides, we treat their conformations using lattice statistics. The theory predicts the salt dependence and binding free energies, of Mg(2+) ions to polynucleotides, of hexamine cobalt(III) to calf thymus DNA, of polyamines to T7 DNA, of oligolysines to poly(U) and poly(a), and of tripeptides to heparin, a charged polysaccharide. One parameter is required to obtain absolute binding constants, the distance of closest separation of the ligand to the polyion. Some, but not all, of the binding entropies and enthalpies are also predicted accurately by the model.
离子配体可以与诸如DNA或带电荷的多糖等聚电解质结合。我们开发了一种泊松-玻尔兹曼处理方法，以在低配体浓度的极限下计算作为配体电荷和盐浓度函数的结合常数。对于柔性链配体，如寡肽，我们使用晶格统计来处理它们的构象。该理论预测了镁离子与多核苷酸、六胺钴（III）与小牛胸腺DNA、多胺与T7 DNA、寡聚赖氨酸与聚尿苷酸和聚腺苷酸以及三肽与带电荷的多糖肝素之间的盐依赖性和结合自由能。获得绝对结合常数需要一个参数，即配体与聚离子最接近分离的距离。该模型还能准确预测部分（但不是全部）的结合熵和焓。
