Structure of fully hydrated fluid phase lipid bilayers with monounsaturated chains
Structure of fully hydrated fluid phase lipid bilayers with monounsaturated chains
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DOI：
10.1007/s00232-005-7006-8
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发表时间：
2005-01-01
影响因子：
2.4
通讯作者：
Nagle, JF
中科院分区：
文献类型：
--
作者：
Kucerka, N;Tristram-Nagle, S;Nagle, JF
在30 ℃下获得的定量结构的完全水合的流体相的棕榈酰油酰磷脂酰胆碱（POPC），与一个双键上的sn-2烃链，和dierucoylphosphatidylcholine（di 22：1 PC），与一个双键上的每个烃链。使用三种方法的组合获得两种脂质的形状因子F（q（z））。(1)体积测量提供F（0）。(2)来自挤出的单层囊泡的X射线散射提供垂直条F（q（z））垂直条用于低qz。(3)来自双层的定向堆叠的漫射X射线散射提供垂直条F（q（z））垂直条用于高q（z）。此外，使用方法（2）的数据被添加到我们使用方法（1）和（3）获得的二油酰磷脂酰胆碱（DOPC）的最新数据中;新的DOPC数据与最新数据以及（4）我们使用液晶X射线方法获得的旧数据非常一致。我们使用混合电子密度模型从这些形状因子获得结构结果。DOPC的单位脂质面积（A）结果为72.4 +/- 0.5埃（2），与我们早期的出版物一致，我们发现di 22：1 PC的A = 69.3 +/- 0.5埃（2），POPC的A = 68.3 +/- 1.5埃（2）。我们得到的值为五个不同的平均厚度：疏水，立体，头-头，磷酸盐-磷酸盐和Luzzati。这三种脂质和我们最近的二肉豆蔻酰磷脂酰胆碱（DMPC）测定的结果的比较提供了定量的措施，双层结构上的不饱和度的影响。我们的研究结果表明，具有一个单不饱和链的脂质具有更接近于具有两个单不饱和链的脂质的定量双层结构，而不是具有两个完全饱和链的脂质。
Quantitative structures are obtained at 30 degrees C for the fully hydrated fluid phases of palmitoyloleoylphosphatidylcholine (POPC), with a double bond on the sn-2 hydrocarbon chain, and for dierucoylphosphatidylcholine (di22: 1PC), with a double bond on each hydrocarbon chain. The form factors F(q(z)) for both lipids are obtained using a combination of three methods. (1) Volumetric measurements provide F(0). (2) X-ray scattering from extruded unilamellar vesicles provides vertical bar F(q(z))vertical bar for low qz. (3) Diffuse X-ray scattering from oriented stacks of bilayers provides vertical bar F(q(z))vertical bar for high q(z). Also, data using method (2) are added to our recent data for dioleoylphosphatidylcholine (DOPC) using methods (1) and (3); the new DOPC data agree very well with the recent data and with (4) our older data obtained using a liquid crystallographic X-ray method. We used hybrid electron density models to obtain structural results from these form factors. The result for area per lipid (A) for DOPC 72.4 +/- 0.5 angstrom(2) agrees well with our earlier publications, and we find A = 69.3 +/- 0.5 angstrom(2) for di22:1PC and A = 68.3 +/- 1.5 angstrom(2) for POPC. We obtain the values for five different average thicknesses: hydrophobic, steric, head-head, phosphate-phosphate and Luzzati. Comparison of the results for these three lipids and for our recent dimyristoylphosphatidylcholine (DMPC) determination provides quantitative measures of the effect of unsaturation on bilayer structure. Our results suggest that lipids with one monounsaturated chain have quantitative bilayer structures closer to lipids with two monounsaturated chains than to lipids with two completely saturated chains.