HOW MEMBRANE CHAIN-MELTING PHASE-TRANSITION TEMPERATURE IS AFFECTED BY THE LIPID CHAIN ASYMMETRY AND DEGREE OF UNSATURATION - AN EFFECTIVE CHAIN-LENGTH MODEL
HOW MEMBRANE CHAIN-MELTING PHASE-TRANSITION TEMPERATURE IS AFFECTED BY THE LIPID CHAIN ASYMMETRY AND DEGREE OF UNSATURATION - AN EFFECTIVE CHAIN-LENGTH MODEL
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DOI：
10.1021/bi00243a021
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发表时间：
1991-07-23
期刊：
影响因子：
2.9
通讯作者：
CEVC, G
中科院分区：
文献类型：
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作者：
CEVC, G
分析了碳氢化合物对脂链熔融相变温度的影响。膜流化温度随有效链长的增加而增加，有效链长与填充良好的烃区域的厚度成正比。后者，作为一项规则，增加的长度最长的有序和对齐的片段在每个链。这一结论与膜内部链堆积减少的原因无关：链不饱和（有效地将双键分开的两个烃链段重叠）或链不对称（导致末端烃链段失去紧密接触）都影响有效链长尺度上的双层链熔融相变温度ε。反式不饱和的热力学后果是约50%小于顺式构象中的双键的影响，由于较小的膜扰动由前双键。介绍了一个简单的定量模型，用于分析磷脂链的熔融相行为。这种新的模型允许定量预测的链熔融转变温度仅在已知的脂质化学组成的基础上。它还解释了脂质对碳氢化合物类型和附着的敏感性。模型与实验数据的一致性通常好于99%以内，因此与实验分散性相当，即使仅使用少数或不使用可调参数。膜流化温度计算一些潜在的有趣的，也尚未探索，磷脂，和生物学意义的有效链长的概念进行了讨论。
Hydrocarbon effects on the lipid chain-melting phase-transition temperature are analyzed. The membrane fluidization temperature is shown to increase with the effective chain length, which is proportional to the thickness of the well-packed hydrocarbon region. The latter, as a rule, increases with the length of the longest ordered and aligned segment on each chain. This conclusion is independent of the cause for the reduced chain packing in membrane interior: chain unsaturation (which effectively decouples the two hydrocarbon segments disjoined by a double bond) or chain asymmetry (which causes the terminal hydrocarbon segments to lose close contact) both affect the bilayer chain-melting phase-transition temperature comparably on the effective chain-length scale. Thermodynamic consequences of the trans unsaturation are approximately 50% smaller than the effects of the double bonds in the cis conformation, owing to the smaller membrane perturbation by the former double bonds. A simple quantitative model is introduced for the analysis of the phospholipid chain-melting phase behavior. This new model permits quantitative predictions of the chain-melting transition temperature solely on the basis of the known lipid chemical composition. It also explains lipid sensitivity to the hydrocarbon type and attachment. The model agreement with the experimental data is usually better than to within 99% and thus comparable to experimental scatter, even when only a few or no adjustable parameters are used. The membrane fluidization temperature is calculated for a number of potentially interesting, also as yet unexplored, phospholipids, and the biological significance of the effective chain-length concept is discussed.