Supramolecular Formation in Lipids

本研究旨在为生物膜的基本结构提供证据，特别是磷脂组成的超分子结构。波纹结构在磷脂中具有介观结构的有趣特征。在双棕榈酰磷脂酰胆碱中，二级波纹结构出现在亚稳态。此外，还澄清了亚稳态出现的条件。在磷脂/胆固醇体系中，波纹重复距离的温度依赖性已经用正常波纹结构的温度依赖性来解释。在类似的体系中，磷脂分子具有不饱和烃链，相图的总体行为在磷脂中几乎是共同的。在磷脂/醇体系中，通过改变多种磷脂和醇中烃类链的长度，系统地研究了指间相的结构。从多层膜表面法向的电子密度分布出发，提出了交错结构的模型。在月桂酰磷脂酰胆碱中，在波纹相和常规液晶相之间发现了一种新的液晶相，这种新的液晶结构比常规结构具有更少的无序烃链。聚赖氨酸和酸性磷脂系统作为外源性蛋白质和脂质的生物膜模型，已被研究。发现它们之间的主要相互作用是静电相互作用。

This study aims to get evidence for the basic structure of biomembranes, especially to focus upon the supramolecular structure composed of phospholipids. Ripple structure possesses interesting features from mesoscopic structure appearing in phospholipids. In dipalmitoylphosphatidylcholine, it has been found that the secondary ripple structure appears in a metastable state. Furthermore, the condition of the appearance of the metastable state has been clarified. In a phospholipis/cholesterol system, the temperature dependence of the ripple repeat distance has been explained in terms of that for the normal ripple structure. In a similar system, in which a phospholipid molecule has unsaturated hydrocarbon chains, the overall behavior of the phase diagram is almost common among the phospholipids. In a phospholipid/alcohol system, structural study on the interdigitated phase has been performed systematically by changing the length of hydrocarbon chain in a variety of phospholipids and various alcohols. From the electron density profile in the direction normal to the surface of multilamellar, a model of the interdigitated structure has been proposed. In lauroylphosphatidylcholine, a new liquid crystalline phase has been found between ripple and usual liquid crystalline phases : the new liquid crystalline structure has less disordered hydrocarbon chains than in the usual structure. As a model of biomembranes of an extrinsic protein and lipids, a system of poly(L-lysine) and acidic phospholipis has been studied. The main interaction between them has been found to be electrostatic one.