Peyrin E, Guillaume Y C, Morin N, Guinchard C
Laboratoire de Chimie Analytique, Faculte de Medecine et Pharmacie, Besancon, France.
Anal Chem. 1998 Jul 15;70(14):2812-8. doi: 10.1021/ac980039a.
In a chromatographic system using human serum albumin (HSA) as a stationary phase, D,L dansyl amino acids as solutes, and sucrose as a mobile-phase modifier, a study on the surface tension effect of sugar on compound retention was carried out by varying the salting-out agent concentration c and the column temperature T. The thermodynamic parameters for solute transfer from the mobile to the stationary phase were determined from linear van't Hoff plots. An enthalpy-entropy compensation study revealed that the type of interaction between solute and HSA was independent of the molecular structure of the dansyl amino acids and the mobile-phase composition. An analysis of the experimental variations in the retention factor and the enantioselectivity values with c was performed using a theoretical model. It was shown that the decrease in solute retention accompanying the sucrose concentration increase was principally governed by a structural rearrangement of the binding cavity due to the increased surface tension effects. The cavity apolar residues were assumed to fold out of contact with the medium in order to reduce the surface area accessible to sucrose molecules, thus implying a restriction of the curvature radius of the cavity. Such behavior caused a decrease in the hydrophobic interaction for ligand binding on HSA explaining the observed thermodynamic parameter trends over the sucrose concentration range.
在一个以人血清白蛋白（HSA）为固定相、D,L-丹磺酰氨基酸为溶质、蔗糖为流动相改性剂的色谱系统中，通过改变盐析剂浓度c和柱温T，开展了一项关于糖对化合物保留的表面张力效应的研究。从线性范特霍夫图确定了溶质从流动相转移到固定相的热力学参数。焓-熵补偿研究表明，溶质与HSA之间的相互作用类型与丹磺酰氨基酸的分子结构和流动相组成无关。使用理论模型对保留因子和对映选择性值随c的实验变化进行了分析。结果表明，随着蔗糖浓度增加溶质保留的降低主要是由于表面张力效应增加导致结合腔的结构重排。假定腔的非极性残基折叠起来与介质脱离接触，以减少蔗糖分子可接触的表面积，从而意味着腔的曲率半径受到限制。这种行为导致配体与HSA结合的疏水相互作用降低，解释了在蔗糖浓度范围内观察到的热力学参数趋势。
