FLUORESCENCE STUDIES OF BIOPHYSICAL PROPERTIES OF POLYUNSATURATED PHOSPHOLIPIDS

神经元和视网膜组织富含磷脂， 一个或两个多不饱和酰基链。 在我们的研究中， 发现证据支持磷脂酰基链的新模型 包装，在这个实验室开发，其中包括形成 膜表面的侧域。 这种域的形成 是由饱和的sn-1链的强相互作用驱动的 相对于多不饱和Sn-2链的较弱相互作用。 双饱和（di 16：0）的混合物的差示扫描量热法 PC和二聚不饱和（di 22：6 n3）PC表现出侧相 在凝胶相中分离。 荧光寿命研究 二苯基己三烯（DPH）在这些混合脂质系统也表明， 在凝胶和液晶状态下存在分离的域。 这种结构域的形成会在膜上产生富含 在高度不饱和的酰基链中。 位于这些区域的蛋白质 会有不同的功能特性， 膜的区域。 此外，我们发现胆固醇 优先与饱和酰基链相互作用，因此 倾向于集中在膜的更饱和的区域。 我们 还发现乙醇对变视紫红质II形成的影响 在不饱和脂质中更高。 域的影响可以 导致膜的区域特别敏感， 醇和其它膜可溶性试剂。 慢性酒精暴露是 已知对乙醇诱导的膜紊乱产生抵抗力 在体外测量，通常称为膜耐受性。 的 通过多不饱和酰基链增强醇的作用， 再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20：4 n6， 22：6 n3，可能为膜的发育提供了解释 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.