Barry J A, Trouard T P, Salmon A, Brown M F
Department of Chemistry, University of Arizona, Tucson 85721.
Biochemistry. 1991 Aug 27;30(34):8386-94. doi: 10.1021/bi00098a016.
Polyunsaturated fatty acids are widely distributed components of biological membranes and are believed to be involved in many biological functions. However, the mechanisms by which they act on a molecular level are not understood. To further investigate the unique properties of omega 3 polyunsaturated phospholipid bilayers, deuterium nuclear magnetic resonance (2H NMR) studies have been made of the liquid-crystalline (L alpha) and gel phases of a homologous series of mixed-chain phosphatidylcholines containing docosahexaenoic acid: (per-2H-n:0)(22:6)PC, where n = 12, 14, 16, and 18. The moments of the 2H NMR lineshapes have been evaluated, and from these the warming and cooling main phase transition temperatures were determined. The transition temperatures of the mixed-chain series were found to be significantly lower than those of the corresponding lipids in the disaturated series, di(per-2H-n:0)PC, with hystereses ranging from 2 to 14 degrees C. Distinct effects of the docosahexaenoyl chain on bilayer order were found, though these effects varied across the mixed-chain series. In evaluating the moment data, an empirical method for normalizing the moments with respect to differences in temperature was applied, in addition to using the reduced temperature method. For the systems studied here, the method of normalization had no significant effect on the interpretation of the moment data.
多不饱和脂肪酸是生物膜中广泛分布的成分，被认为参与了许多生物学功能。然而，它们在分子水平上的作用机制尚不清楚。为了进一步研究ω-3多不饱和磷脂双层的独特性质，对一系列含有二十二碳六烯酸的混合链磷脂酰胆碱的液晶（Lα）相和凝胶相进行了氘核磁共振（2H NMR）研究：(全氘代-n:0)(22:6)PC，其中n = 12、14、16和18。对2H NMR线形的矩进行了评估，并由此确定了升温及降温时的主要相变温度。发现混合链系列的相变温度明显低于相应的双饱和系列脂质二（全氘代-n:0）PC的相变温度，滞后范围为2至14摄氏度。虽然二十二碳六烯酰链对双层有序性的影响在整个混合链系列中有所不同，但已发现其具有明显的影响。在评估矩数据时，除了使用折合温度法外，还应用了一种针对温度差异对矩进行归一化的经验方法。对于此处研究的体系，归一化方法对矩数据的解释没有显著影响。
