Wolff R L, Entressangles B
I.S.T.A.B., Laboratoire de Lipochimie Alimentaire, Université de Bordeaux, Talence, France.
Biochim Biophys Acta. 1994 Mar 3;1211(2):198-206. doi: 10.1016/0005-2760(94)90269-0.
In vivo-modified phospholipids from rat liver mitochondria were used to study the effect of trans-fatty acid incorporation into phospholipids on the steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) embedded in phospholipid liposomes. Pure fractions of mitochondria phospholipids were prepared and analyzed for their fatty acid compositions and fatty acid positional distribution. In rats fed a diet enriched with trielaidin, elaidic acid (trans-9 18:1 acid) was extensively incorporated in position 1 of phosphatidylcholine (PC; 31% of fatty acids esterified to this position), phosphatidylethanolamine (PE; 42.5%) and phosphatidylinositol (PI; 43%). Less than 10% of the incorporated elaidic acid was esterified to position 2 of these phospholipids. More than 90% of elaidic acid esterified to position 1 displaced saturated acids. Consequently, about one-third of PC molecules and two-fifths of PE and PI molecules contained one molecule of elaidic acid instead of one saturated fatty acid molecule in their 1-position. On the other hand, cardiolipin, which is naturally practically devoid of saturated acids, was particularly resistant to elaidic acid incorporation. The fluorescence polarization of DPH incorporated in liposomes made of PC-PI and of PC-PI-PE from liver mitochondria of rats fed or not fed elaidic acid was measured. No significant differences between phospholipids containing or not containing elaidic acid could be detected. Values of DPH fluorescence polarization for all samples were comprized between 0.133 and 0.135 at 25 degrees C. We thus conclude that when elaidic acid replaces saturated fatty acids in phospholipids, even in a high proportion (one-third), the physical state of acyl chains in the hydrophobic core of membranes is not grossly modified. Thus, elaidic acid seems to behave like a saturated fatty acid, not only biochemically for the acylation of phospholipids, but also physically.
来自大鼠肝脏线粒体的体内修饰磷脂被用于研究反式脂肪酸掺入磷脂对嵌入磷脂脂质体中的1,6 - 二苯基 - 1,3,5 - 己三烯（DPH）稳态荧光偏振的影响。制备了线粒体磷脂的纯级分，并分析了它们的脂肪酸组成和脂肪酸位置分布。在喂食富含三油酸甘油酯饮食的大鼠中，反油酸（反式 - 9 18:1酸）大量掺入磷脂酰胆碱（PC）的1位（酯化到该位置的脂肪酸的31%）、磷脂酰乙醇胺（PE；42.5%）和磷脂酰肌醇（PI；43%）。掺入的反油酸中不到10%酯化到这些磷脂的2位。酯化到1位的反油酸超过90%取代了饱和酸。因此，约三分之一的PC分子以及五分之二的PE和PI分子在其1位含有一个反油酸分子而非一个饱和脂肪酸分子。另一方面，天然几乎不含饱和酸的心磷脂对反油酸掺入特别有抗性。测量了喂食或未喂食反油酸的大鼠肝脏线粒体中由PC - PI以及PC - PI - PE制成的脂质体中掺入的DPH的荧光偏振。未检测到含或不含反油酸的磷脂之间有显著差异。在25℃时，所有样品的DPH荧光偏振值在0.133至0.135之间。因此我们得出结论，当反油酸在磷脂中取代饱和脂肪酸时，即使比例很高（三分之一），膜疏水核心中酰基链的物理状态也没有明显改变。因此，反油酸似乎不仅在磷脂酰化的生化方面，而且在物理方面都表现得像饱和脂肪酸。
