FLUORESCENCE STUDIES OF BIOPHYSICAL PROPERTIES OF POLYUNSATURATED PHOSPHOLIPIDS

神经细胞和视网膜组织中的磷脂含量很高，含有 一个或两个多不饱和的酰基链。在我们的研究中，我们有 发现支持磷脂酰链新模型的证据 包装，在这个实验室开发的，它涉及形成 膜表面的侧域。这种结构域的形成 是由饱和的sn-1链的强相互作用驱动的 相对于多不饱和Sn2链之间较弱的相互作用。 一种饱和(di16：0)混合物的差示扫描量热法 PC和二聚不饱和(di22：6n3)PC呈现侧向相态 凝胶相中的分离。分子的荧光寿命研究 这些混合脂质体系中的二苯基己三烯(DPH)也表明 在凝胶和液晶状态下都存在单独的结构域。 这种类型的结构域形成将产生富含膜的区域 在高度不饱和的酰基链中。位于这些区域的蛋白质 将具有与饱和程度更高的那些不同的功能特性 膜的区域。此外，我们还发现胆固醇 优先与饱和的酰基链相互作用，因此 倾向于集中在膜的更饱和的区域。我们 还发现乙醇对后视紫红质II的形成有影响 在更多的不饱和脂肪中含量更高。域的影响可能 导致膜上特别敏感的区域 醇类等膜溶媒。慢性酒精暴露是 已知对乙醇诱导的膜紊乱具有抵抗力 在体外测量，通常称为膜耐受性。这个 多不饱和酰基链对醇作用的增强作用， 加上在这个实验室里观察到的酒精 消耗长链多不饱和脂肪酸，如20：4n6和 22：6n3，这可能为膜的形成提供了解释 宽容。

Neuronal and retinal tissue are high in phospholipids which contain either one or two polyunsaturated acyl chains. In our studies, we have found evidence to support a novel model for phospholipid acyl chain packing, developed in this laboratory, which involves the formation of lateral domains in the surface of the membrane. This domain formation is driven by the strong interactions of the saturated sn-1 chains relative to the weaker interactions of the polyunsaturated sn-2 chains. Differential scanning calorimetry of mixtures of a disaturated (di16:0) PC and a dipolyunsaturated (di22:6n3) PC demonstrate lateral phase separation in the gel phase. Fluorescence lifetime studies of diphenylhexatriene (DPH) in these mixed lipid systems also indicates the presence of separate domains in both the gel and liquid crystal states. This type of domain formation would create regions of the membrane rich in highly unsaturated acyl chains. Proteins located in these regions would have different functional properties than those in more saturated regions of the membrane. In addition, we have found that cholesterol preferentially interacts with saturated acyl chains and would therefore tend to concentrate in the more saturated regions of the membrane. We have also found that the effect of ethanol on metarhodopsin II formation is greater in more unsaturated lipids. The effect of domains could result in regions of the membrane which are particularly sensitive to alcohols and other membrane soluble agents. Chronic alcohol exposure is known to cause resistance to ethanol-induced membrane disordering measured in vitro, usually referred to as membrane tolerance. The potentiation of the effect of alcohols by polyunsaturated acyl chains, coupled with the observation made in this laboratory that alcohol depletes the long-chain polyunsaturated fatty acids, such as 20:4n6 and 22:6n3, may provide an explanation for the development of membrane tolerance.