Heimburg T
Max-Planck-Institut für biophysikalische Chemie, AG Membrane Thermodynamics, Am Fassberg 11, 37077 Göttingen, Germany.
Biochim Biophys Acta. 1998 Dec 9;1415(1):147-62. doi: 10.1016/s0005-2736(98)00189-8.
Changes in the internal energy of lipids with temperature are related to both lipid volume and area changes. Close to the chain melting transition of lipid bilayers volume and enthalpy fluctuations generally follow proportional functions. This makes it possible to calculate the relationship between membrane excess heat capacity with lipid volume, area compressibility and the membrane bending modulus, if the area fluctuations of the two monolayers are assumed to be mainly decoupled. Thus, compressibility and elasticity display pronounced maxima at the chain melting transition. These maxima can also be related to pronounced minima of the sound velocity in the lipid transition range, which were found in ultrasonic experiments. In the present study heat capacity profiles and volume changes were obtained. The compressibilities and the bending modulus were then deduced from the specific heat. The relevance of these findings for structural transitions and for the curvature dependence of heat capacities is discussed.
脂质内能随温度的变化与脂质体积和面积变化都有关系。接近脂质双层的链熔化转变时，体积和焓波动通常遵循比例函数。如果假设两个单分子层的面积波动主要是解耦的，那么就可以计算膜过量热容量与脂质体积、面积压缩性和膜弯曲模量之间的关系。因此，压缩性和弹性在链熔化转变处显示出明显的最大值。这些最大值也与脂质转变范围内声速的明显最小值有关，这是在超声实验中发现的。在本研究中，获得了热容量曲线和体积变化。然后从比热推导出压缩性和弯曲模量。讨论了这些发现对于结构转变以及热容量曲率依赖性的相关性。
