Freire E, Biltonen R
Biochim Biophys Acta. 1978 Dec 4;514(1):54-68. doi: 10.1016/0005-2736(78)90076-7.
It is demonstrated that the bilayer partition function can be numerically obtained from scanning calorimetric data without assuming a particular model for the gel-liquid crystalline transition. From this partition function, the enthalpy, entropy and volume changes accompanying the transition can be calculated. In the limit of very large systems, the method of the grand partition function allows calculation of cluster model distribution functions from which average sizes of gel and liquid-crystal clusters, cluster densities and equilibrium fluctuations are obtained. These results indicate that the main transition in phospholipid bilayers proceeds through the formation of clusters and that these clusters are not static domains but highly fluctuating entities. These fluctuations in cluster size are approximately equal to the average cluster size and give rise to localized density and volume fluctuations. The magnitude of these fluctuations is affected by the radius of curvature of the bilayer and by the addition of small molecular weight compounds to the system.
结果表明，无需对凝胶 - 液晶转变假设特定模型，双层分配函数可从扫描量热数据中通过数值方法获得。根据该分配函数，可计算出转变过程中伴随的焓变、熵变和体积变化。在非常大的系统极限情况下，巨配分函数方法允许计算团簇模型分布函数，由此可获得凝胶和液晶团簇的平均尺寸、团簇密度和平衡涨落。这些结果表明，磷脂双层中的主要转变是通过团簇的形成进行的，并且这些团簇不是静态区域，而是高度波动的实体。团簇尺寸的这些涨落大约等于平均团簇尺寸，并导致局部密度和体积涨落。这些涨落的幅度受双层曲率半径以及向系统中添加小分子化合物的影响。
