Urien S, Nguyen P, Berlioz S, Brée F, Vacherot F, Tillement J P
Laboratoire de Pharmacologie, Faculté de Médicine, Université Paris XII, France.
Biochem J. 1994 Aug 15;302 ( Pt 1)(Pt 1):69-72. doi: 10.1042/bj3020069.
The binding interactions of four ligands differing in acid-base properties with human serum albumin (HSA) were examined as a function of temperature. Binding to HSA decreased with increasing temperature for all four ligands. The bound and free ligand concentrations obtained at different temperatures were satisfactorily fitted to a model that incorporates the effect of temperature as an independent covariable and that directly allows the estimation of the enthalpic and entropic components of the ligand-albumin interaction, along with the precision of this estimation. Using this analysis, the binding of acidic ligands could be resolved into two classes of saturable sites, with the determination of the corresponding number of sites, whereas interpretation of binding data at each isolated temperature allowed only the determination of one saturable plus one non-saturable class of site. The thermodynamic constants indicate that binding of ionizable ligands to HSA involves electrostatic plus hydrophobic interactions, whereas only hydrophobic interactions are involved in binding to a second low-affinity class of site when present. Binding of non-ionizable ligands resembles that of the second class of low-affinity sites of ionizable ligands.
研究了四种酸碱性质不同的配体与人类血清白蛋白（HSA）的结合相互作用随温度的变化情况。对于所有四种配体，其与HSA的结合均随温度升高而降低。在不同温度下获得的结合配体和游离配体浓度，能够很好地拟合一个模型，该模型将温度效应作为一个独立协变量纳入其中，并且可以直接估计配体 - 白蛋白相互作用的焓和熵成分，以及这种估计的精度。通过这种分析，酸性配体的结合可分为两类可饱和位点，并能确定相应的位点数量，而在每个单独温度下对结合数据的解释仅能确定一类可饱和位点加一类非可饱和位点。热力学常数表明，可电离配体与HSA的结合涉及静电和疏水相互作用，而当存在第二类低亲和力位点时，与该位点的结合仅涉及疏水相互作用。非可电离配体的结合类似于可电离配体第二类低亲和力位点的结合。
