FLUORESCENCE STUDIES OF POLYUNSATURATED PHOSPHOLIPID MEMBRANES

酒精引起的多不饱和脂类耗竭改变生理 以及生物膜的功能特性。慢性酒精 已知暴露会导致对乙醇诱导的细胞膜产生抵抗性。 在体外测量的无序性。我们实验室的荧光研究 确认此反应在大鼠戒断后2至3天恢复 肝脏微粒体。用DPH检测法测量大块膜的“流动性” 对照组和肝脏的基底膜顺序没有差异 戒断组的微粒体数。然而，一种局部的膜 探针TMA-DPH检测到明显更高的基底膜顺序 戒断后24小时组。荧光探针的运动 在这些双层的特定区域的定位表明酒精诱导 脂类成分的变化对膜组织的影响非常明显 脂类结构域。此外，我们的实验室已经证明酒精 消耗长链多不饱和脂肪酸，如20：4N6和 膜来源为22：6N3。我们假设有一个专业领域 22：6-磷脂在生物学中的定位和作用 膜。为了验证这一假设，22：6n3的物理环境 和其他多不饱和磷脂已经使用 膜的荧光各向异性和差示扫描量热法 准备工作。我们发现在确定的条件下，双分子层 含有22：6n3的物种比双层分子更紧密地聚集在一起 含有较少双键的物种。然而，相关时间 相同的标记样本表明，沿 随着脂肪酰基链的增加，脂肪酰链变得越来越无序 不饱和。

Alcohol-induced depletion of polyunsaturated lipids alters the physical and functional properties of biological membranes. Chronic alcohol exposure is known to cause resistance to ethanol-induced membrane disordering measured in vitro. Fluorescence studies in our laboratory confirm that this response recovers 2 to 3 days post-withdrawal in rat liver microsomes. Bulk membrane "fluidity" measurements with DPH detect no difference in basal membrane order between controls and liver microsomes from the withdrawal group. However, a localized membrane probe, TMA-DPH, detected a significantly higher basal membrane order in the 24 hours post-withdrawal group. Motions of fluorescent probes localized in specific areas of these bilayers suggest that alcohol-induced changes in lipid composition affect membrane organization in very distinct lipid domains. Furthermore, our laboratory has shown that alcohol depletes the long chain polyunsaturated fatty acids such as 20:4n6 and 22:6n3 from membranes. We hypothesize that there is a specialization in the localization and function of the 22:6-phospholipids in biological membranes. To test this hypothesis, the physical environment of 22:6n3 and other polyunsaturated phospholipids have been studied using fluorescence anisotropy and differential scanning calorimetry of membrane preparations. We have found that under defined conditions, bilayers containing 22:6n3 species become more highly packed than bilayers containing species with fewer double bonds. However, correlation times of the same labeled samples indicate that the local environment along the fatty acyl chains becomes increasingly disordered with increasing unsaturation.