Garda H A, Bernasconi A M, Brenner R R
Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), UNLP-CONICET, Facultad de Ciencias Médicas, Argentina.
J Lipid Res. 1994 Aug;35(8):1367-77.
The effect of essential fatty acid deficiency on the structural and dynamic properties of the lipid matrix of rat liver microsomes and erythrocyte membranes was studied. The rate and range of the rotational mobility of 1,6-diphenyl-1,3,5-hexatriene and 2-, 7-, and 12-(9-anthroyloxy)stearate probes in the native membranes and in lipid vesicles prepared with the total lipid extracts of these membranes were evaluated by using differential polarized phase fluorometry. For the anthroyloxystearate probes, two modes of rotation (in and out of the plane of the aromatic anthracene ring) were partially resolved by measuring at different excitation wavelengths. The fat-free diet produces important changes in the fatty acid composition of the different glycerophospholipid classes without affecting the total double-bond number, the relative contents of cholesterol, phospholipid, and protein, and the glycerophospholipid class distribution. The principal changes, more pronounced in liver microsomes than in erythrocytes, are: an increase in nonessential monoene and triene (18:1n-9 and 20:3n-9) and a decrease in essential diene (18:2n-6) and tetraene (20:4n-6). These changes modify the double-bond distribution as a function of the distance from the interphase toward the bilayer interior, with a significant deficit (15% in erythrocytes and 30% in liver microsomes) in the double-bond density in the intermediate region of the membrane leaflet, corresponding to the carbon number 11-12 of an extended saturated acyl chain, and where the 12-anthroyloxystearate probe is located. In spite of the changes in fatty acid composition and double-bond distribution, with the only exception of a slight increase (about 15%) in the "out of the plane" rotation rate of the 7-(9-anthroyloxy)stearate probe in the erythrocyte lipid vesicles, no other significant change is observed. Thus, the changes in fatty acid composition would take place in such a way that at least the average structural and viscotropic properties of the lipid phase of the membrane, sensed by these probes, would be almost exactly compensated.
研究了必需脂肪酸缺乏对大鼠肝微粒体和红细胞膜脂质基质的结构和动力学性质的影响。通过使用差分偏振相荧光法评估了1,6 - 二苯基 - 1,3,5 - 己三烯和2 -、7 - 和12 -（9 - 蒽氧基）硬脂酸酯探针在天然膜以及用这些膜的总脂质提取物制备的脂质囊泡中的旋转迁移率的速率和范围。对于蒽氧基硬脂酸酯探针，通过在不同激发波长下测量，部分分辨出了两种旋转模式（芳香蒽环平面内和平面外）。无脂饮食使不同甘油磷脂类别的脂肪酸组成发生重要变化，但不影响总双键数、胆固醇、磷脂和蛋白质的相对含量以及甘油磷脂类别的分布。主要变化在肝微粒体中比在红细胞中更明显，包括：非必需单烯和三烯（18:1n - 9和20:3n - 9）增加，必需二烯（18:2n - 6）和四烯（20:4n - 6）减少。这些变化改变了双键分布，其作为从界面到双层内部距离的函数，在膜小叶的中间区域（对应于延伸饱和酰基链的碳数11 - 12，且12 - 蒽氧基硬脂酸酯探针位于此处）双键密度显著降低（红细胞中为15%，肝微粒体中为30%）。尽管脂肪酸组成和双键分布发生了变化，但唯一的例外是红细胞脂质囊泡中7 -（9 - 蒽氧基）硬脂酸酯探针的“平面外”旋转速率略有增加（约15%），未观察到其他显著变化。因此，脂肪酸组成的变化将以这样一种方式发生，即至少这些探针所感知的膜脂质相的平均结构和粘滞性质几乎能被精确补偿。
