The conformational behaviour of phosphatidylcholine and phosphatidyl acid membranes derived from octadec-14-ynoic and octadec-9-ynoic acid is studied by FTIR spectroscopy comprising both the liquid crystalline and gel phases. In the vicinity of the transition from the gel to the liquid crystalline phase the conformational changes of the acyl chains are followed by the analysis of the CH2 stretching bands and CH2 wagging band progressions. In the liquid crystalline phase a quantitative determination of the amounts of gauche-trans-gauche, double gauche, and end gauche conformers is achieved by the analysis of the CH2 wagging band region. In this connection, several model compounds (hex-2-yne, and hex-3-yne, oct-4-yne) have been examined to assist the assignment of a special vibration band at 1328 cm-1 due to the CH2–C3C unit. The results for the phospholipids studied here clearly demonstrate that the conformational properties critically depend on their actual lipid structure, sample composition and sample temperature. The derived data are discussed in conjunction with earlier investigations of more “conventional’' lipid systems—mainly containing saturated acyl chains—to evaluate the specific influence of the incorporation of the C–C triple bond into the fatty acid chains.
通过包含液晶相和凝胶相的 FTIR 光谱研究了十八十六-14-ynoic 和十八十六-9-ynoic 酸衍生的
磷脂酰
胆碱和
磷脂酰酸膜的构象行为。在从凝胶到液晶相的转变附近,通过分析
CH2 拉伸带和 摇摆带级数来跟踪酰基链的构象变化。在液晶相中,通过分析 摇摆带区域实现了gauche-trans-gauche、双gauche和末端gauche构象异构体的量的定量测定。在这方面,已经检查了几种模型化合物(hex-2-yne、hex-3-yne、oct-4-yne),以协助分配由于 –C3C 导致的 1328 cm-1 处的特殊振动带单元。这里研究的
磷脂的结果清楚地表明,构象特性关键取决于它们的实际脂质结构、样品组成和样品温度。结合早期对更“常规”脂质系统(主要包含饱和酰基链)的研究,讨论了得出的数据,以评估 C-C 三键并入
脂肪酸链的具体影响。