Zerouga M, Jenski L J, Stillwell W
Department of Biology, Indiana University - Purdue University at Indianapolis 46202, USA.
Biochim Biophys Acta. 1995 Jun 14;1236(2):266-72. doi: 10.1016/0005-2736(95)00058-b.
Docosahexaenoic acid (DHA) is the longest and most unsaturated of the n - 3 fatty acids found in membranes. Although a number of membrane properties have been demonstrated to be affected by the presence of this fatty acid, its mode of action has yet to be clearly elucidated. Prior reports on biological membranes have not distinguished the effect of mono-docosahexaenoyl phospholipids from those caused by phospholipids containing docosahexaenoic acid in both chains. This report compares properties of monolayers and bilayers composed of either 1-stearoyl-2-linolenoyl-sn-glycero-3-phosphocholine (as a control), 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine or 1,2-di-docosahexaenoyl-sn-glycero-3-phosphocholine. When compared to the mono-DHA phosphatidylcholine (PC), the di-DHA PC occupies a much larger area/molecule, supports a more fluid and permeable bilayer, and is less susceptible to peroxidation. Monolayers made from either phospholipid are not condensable by cholesterol. We suggest many of the membrane properties linked to the presence of DHA may be the result of phospholipids which have lost their normal positional selectivity and have incorporated DHA into both positions.
二十二碳六烯酸（DHA）是细胞膜中发现的n-3脂肪酸中碳链最长且不饱和程度最高的。尽管已有多项研究表明这种脂肪酸的存在会影响细胞膜的多种特性，但其作用方式尚未完全阐明。此前关于生物膜的报道并未区分单二十二碳六烯酰磷脂与两条链均含有二十二碳六烯酸的磷脂所产生的影响。本报告比较了由1-硬脂酰-2-亚麻酰-sn-甘油-3-磷酸胆碱（作为对照）、1-硬脂酰-2-二十二碳六烯酰-sn-甘油-3-磷酸胆碱或1,2-二二十二碳六烯酰-sn-甘油-3-磷酸胆碱组成的单层膜和双层膜的特性。与单DHA磷脂酰胆碱（PC）相比，双DHA PC每个分子占据的面积更大，形成的双层膜流动性更强、通透性更高，且更不易发生过氧化反应。由这两种磷脂制成的单层膜都不能被胆固醇凝聚。我们认为，许多与DHA存在相关的膜特性可能是由于磷脂失去了正常的位置选择性，并且在两个位置都掺入了DHA所致。
