Wimley W C, White S H
Department of Physiology and Biophysics, University of California, Irvine 92717.
Biochemistry. 1993 Jun 29;32(25):6307-12. doi: 10.1021/bi00076a001.
The free energy of transfer of nonpolar solutes from water to lipid bilayers is often dominated by a large negative enthalpy rather than the large positive entropy expected from the hydrophobic effect. This common observation has led to the concept of the "nonclassical" hydrophobic effect and the idea that the "classical" hydrophobic effect may not drive partitioning in many bilayer systems. We show through measurements of the heat capacity changes associated with the partitioning of tryptophan side-chain analogs into lipid bilayers and into bulk cyclohexane that the hydrophobic effect plays a crucial role regardless of the large negative enthalpy. The results emphasize that bulk-phase measurements are inadequate for describing bilayer partitioning. The experimental approach described should be generally useful for analyzing the bilayer interactions of a broad range of biologically important molecules.
非极性溶质从水转移到脂质双层的自由能通常由一个很大的负焓主导，而非疏水效应所预期的很大的正熵。这一常见现象催生了“非经典”疏水效应的概念，以及“经典”疏水效应可能在许多双层系统中并不驱动分配的观点。我们通过测量与色氨酸侧链类似物分配到脂质双层和本体环己烷中相关的热容变化表明，无论存在很大的负焓，疏水效应都起着关键作用。结果强调，本体相测量不足以描述双层分配。所描述的实验方法对于分析广泛的生物学重要分子的双层相互作用通常应是有用的。
