Mizushima H, Fukasawa J, Suzuki T
Wakayama Research Laboratories, Kao Corporation, Japan.
J Lipid Res. 1996 Feb;37(2):361-7.
The phase properties and structural characteristics of stratum corneum (SC) lipid lamellae have been a subject of considerable interest. To clarify the individual role of the stratum corneum constituent lipids, such as ceramides, free fatty acids, and cholesterol, we investigated the thermotropic properties and aggregation structures of a pseudo-ceramide/stearic acid (1/1 mole ratio)-cholesterol system, which is a simplified model for the natural lipids. Differential scanning calorimetry (DSC) detected decreases of melting entropies (delta Sm) by the incorporation of cholesterol into both anhydrous and hydrated equimolar mixture of pseudo-ceramide (SLE) and stearic acid. Moreover, there was a linear relationship between the cholesterol content and the melting entropies in the region of 0-33 mol% cholesterol for both the anhydrous and hydrate lipids. In addition, as the concentration of cholesterol increased, a liquid lateral packing (4.5 A) appeared in the wide-angle X-ray diffraction and the intensity of a hexagonal packing (4.15 A) decreased. The results from the present study strongly follow the idea that cholesterol can regulate the mobility of hydrocarbon chains of the natural stratum corneum lipid bilayer, which is primarily responsible for the barrier properties.
角质层（SC）脂质片层的相特性和结构特征一直是人们相当感兴趣的课题。为了阐明角质层组成脂质（如神经酰胺、游离脂肪酸和胆固醇）的各自作用，我们研究了一种假神经酰胺/硬脂酸（1/1摩尔比）-胆固醇体系的热致性质和聚集结构，该体系是天然脂质的简化模型。差示扫描量热法（DSC）检测到，在无水和水合等摩尔混合的假神经酰胺（SLE）和硬脂酸中加入胆固醇后，熔化熵（δSm）降低。此外，对于无水和水合脂质，在胆固醇含量为0-33 mol%的区域内，胆固醇含量与熔化熵之间存在线性关系。此外，随着胆固醇浓度的增加，广角X射线衍射中出现了液体侧向堆积（4.5 Å），六方堆积（4.15 Å）的强度降低。本研究结果有力地支持了这样一种观点，即胆固醇可以调节天然角质层脂质双层烃链的流动性，而这主要决定了屏障特性。
