Liu Yu, Kang Shu, Chen Yong, Cao Rui, Shi Jun
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P.R. China.
Comb Chem High Throughput Screen. 2007 Jun;10(5):350-7. doi: 10.2174/138620707781662844.
The molecular recognition behaviors of some representative bile salts by three 3,6'-bridged beta-cyclodextrin dimers with oligo(ethylenediamino) linkers in different lengths, i.e. 3,6'-(ethylenediamino-bridged) beta-cyclodextrin dimer (1), 3,6'-(diethylenetriamino-bridged) beta-cyclodextrin dimer (2), and 3,6'-(triethylenetetraamino-bridged) beta-cyclodextrin dimer (3), were investigated in aqueous phosphate buffer solution (pH 7.20) at 25 degrees C by means of 2D NMR spectroscopy and isothermal titration microcalorimetry. Owing to the cooperative host-linker-guest binding mode between host and guest, these 3,6'-bridged beta-cyclodextrin dimers showed significantly enhanced binding abilities and molecular selectivities as compared with native beta-cyclodextrin through the simultaneous contributions of hydrophobic, hydrogen bond, and electrostatic interactions. Thermodynamically, the inclusion complexations of these beta-cyclodextrin dimers with bile salts were mainly driven by large enthalpic gain, accompanied by slight to moderate entropic loss. An enthalpy-entropy compensation analysis demonstrated that these beta-cyclodextrin dimers experienced large conformational changes and extensive desolvation effect upon inclusion complexation with guest molecules.
在25℃的磷酸盐水缓冲溶液（pH 7.20）中，通过二维核磁共振光谱和等温滴定量热法研究了三种具有不同长度的低聚（乙二胺）连接基的3,6'-桥连β-环糊精二聚体，即3,6'-（乙二胺桥连）β-环糊精二聚体（1）、3,6'-（二乙烯三胺桥连）β-环糊精二聚体（2）和3,6'-（三乙烯四胺桥连）β-环糊精二聚体（3）对一些代表性胆汁盐的分子识别行为。由于主体与客体之间存在协同的主体-连接基-客体结合模式，与天然β-环糊精相比，这些3,6'-桥连β-环糊精二聚体通过疏水、氢键和静电相互作用的协同作用，表现出显著增强的结合能力和分子选择性。从热力学角度来看，这些β-环糊精二聚体与胆汁盐的包合络合主要由较大的焓增驱动，同时伴随着轻微到中等程度的熵减。焓-熵补偿分析表明，这些β-环糊精二聚体在与客体分子形成包合络合物时经历了较大的构象变化和广泛的去溶剂化效应。
