Dehydration induces lateral expansion of polyunsaturated 18:0-22:6 phosphatidylcholine in a new lamellar phase
Dehydration induces lateral expansion of polyunsaturated 18:0-22:6 phosphatidylcholine in a new lamellar phase
复制标题
DOI：
10.1016/s0006-3495(01)75755-4
复制
发表时间：
2001-08-01
影响因子：
3.4
通讯作者：
Gawrisch, K
中科院分区：
文献类型：
--
作者：
Binder, H;Gawrisch, K
为了更好地了解多不饱和磷脂的生物学作用，对sn-1链全氘代1-硬脂酰-2-二十二碳六烯酰-sn-甘油-3-磷酸胆碱（SDPC-d35）的溶致相行为和双层尺寸进行了红外（1 R）线性二色性、NMR和X-射线衍射研究，SDPC-d35是一种混合链饱和（18：0）-多不饱和（22：6 Ω 3）脂质。SDPC膜在一定的温度（T）和相对湿度（RN）下进行水合。在过量的水中，脂质在0-50 ℃的温度范围内仅形成层状相。在脱水时，脂质在T < 15 ℃下经历液晶（L-α）和凝胶（L-β）相之间的主要相变。饱和和多不饱和链在La相中均采用拉伸构象，推测为全反式（硬脂酰基）和角铁或螺旋（二十二碳六烯酰基）。当T > 15 ℃时，在部分水化的样品中发现了一种新的流体层状相（L-alpha（'））。SDPC膜在L-α（′）相中当水被除去时横向膨胀并垂直收缩。这种趋势与典型的脱水引起的膜尺寸变化形成鲜明对比。RH-T相图中相变线的斜率表明，溶致L-α（′）-L-α和L-β-L-α相变分别由焓和熵驱动，并讨论了相变的可能分子起源。比较了SDPC与单不饱和1-棕榈酰-2-油酰-sn-甘油基-3-磷酸胆碱（POPC-d31）膜的性质。
To gain a better understanding of the biological role of polyunsaturated phospholipids, infrared (1R) linear dichroism, NMR, and x-ray diffraction studies have been conducted on the lyotropic phase behavior and bilayer dimensions of sn-1 chain perdeuterated 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (SDPC-d35), a mixed-chain saturated (18:0)-polyunsaturated (22:6 omega3) lipid. SDPC films were hydrated at definite values of temperature (T) and relative humidity (RN). In excess water, the lipid forms exclusively lamellar phases in the temperature range 0-50 degreesC. Upon dehydration the lipid undergoes the main phase transition between the liquid-crystalline (L-alpha) and gel (L-beta) phase at T < 15 degreesC. Both the saturated and polyunsaturated chains adopt a stretched conformation in the La phase, presumably the all-trans (stearoyl) and angle iron or helical (docosahexaenoyl) one. A new fluid lamellar phase (L-alpha(')) was found in partially hydrated samples at T > 15 degreesC. SDPC membranes expand laterally and contract vertically in the L-alpha(') phase when water was removed. This tendency is in sharp contrast to typical dehydration-induced changes of membrane dimensions. The slope of the phase transition lines in the RH-T phase diagram reveal that the lyotropic L-alpha(')-L-alpha and L-beta-L-alpha transitions are driven by enthalpy and entropy, respectively The possible molecular origin of the phase transitions is discussed. The properties of SDPC are compared with that of membranes of monounsaturated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC-d31).