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Polymorphism and Phase Transition Behaviors of Lipids and Related Long-chain Compounds Containing Unsaturated Acyl Chains

脂质及相关含不饱和酰基链长链化合物的多晶型和相变行为

基本信息

批准号：
63470010
负责人：
KOBAYASHI Masamichi
金额：
$ 3.26万
依托单位：
OSAKA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

Phospholipids and glycerides are important materials as main constituents of the cell membranes, bearing the biological functional activities. Naturally occurring lipid compounds consist of long acyl chains joined to a polar group and nearly half of the acyl chains are occupied by unsaturated ones which give the membranes fluidity and promote the biological activity.The aim of this research project is to elucidate the molecular mechanism of the characteristic function of the unsaturated acyl chains. Polymorphic structures in relation to the thermodynamic stability and the behavior of solid-state phase transition for a series of cis-monounsaturated fatty acids as well as cis-unsaturated triglycerides were investigated by means of IR and Raman spectroscopy, X-ray analysis, DSC, etc.Unsaturated fatty acids exhibit very complicated polymorphism. The crystal structures of the gamma and gamma_1 phases of erucic acid and the low-melting and high-melting phases of petroselinic acid were fully determined. The molecular and crystal structures of the alpha and alpha_1 phases of erucic acid were also studied. Conformation of the olefine group, subcell structure of the polymethylene chain segments, polytypic structure of the bimolecular layers, and chain mobility have been clarified as the keynote for understanding the physicochemical properties and the phase transition behaviors of the unsaturated lipid compounds. The order-disorder type thermoreversible gamma <double arrow>alpha and gamma_1<double arrow>alpha_1 transitions occurring in cis-monounsaturated fatty acids were recognized as a partial melting process of the methylsided alkyl chains constituting the lamellar interface. The polymorphism of triblycerides whose 2-position is occupied by an oleoyl chain have been investigated. It has been revealed that a large molecular displacement takes place in a coherent fashion during solid-state transitions in saturated fatty acids.

磷脂和甘油酯是构成细胞膜的重要物质，具有重要的生物学功能。天然的脂类化合物是由长的酰基链连接到一个极性基团，近一半的酰基链被不饱和的酰基链占据，从而使膜具有流动性和促进生物活性。本研究的目的是阐明不饱和酰基链的特征功能的分子机制。用红外光谱、拉曼光谱、X-射线衍射仪、差示扫描量热法等手段研究了一系列顺式单不饱和脂肪酸和顺式不饱和甘油三酯的热力学稳定性和固相转变行为的多态结构。确定了芥酸的伽马相和伽马1相以及石油硒酸的低熔点和高熔点相的晶体结构。研究了芥酸的α相和α1相的分子结构和晶体结构。烯基的构象、聚亚甲基链段的亚胞结构、双分子层的多型性和链的迁移性是理解不饱和脂类化合物的物理化学性质和相变行为的关键。顺式-单不饱和脂肪酸中发生的有序-无序型热可逆伽马-α和双箭-α-α转变被认为是构成片层界面的甲基侧链的部分熔融过程。研究了2位被油酰链占据的甘油三酯的多态。已有研究表明，在饱和脂肪酸的固态转变过程中，大分子置换以一种连贯的方式发生。