Thermodynamics of lipid membrane solubilization by sodium dodecyl sulfate
Thermodynamics of lipid membrane solubilization by sodium dodecyl sulfate
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DOI：
10.1529/biophysj.105.077867
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发表时间：
2006-06-01
影响因子：
3.4
通讯作者：
Blume, Alfred
中科院分区：
文献类型：
--
作者：
Keller, Sandro;Heerklotz, Heiko;Blume, Alfred
我们提供了一个全面的热力学描述脂膜溶解带电洗涤剂。为此，我们研究了阴离子洗涤剂十二烷基硫酸钠（SDS）和两性离子磷脂1-棕榈酰-2-油酰-sn-甘油-3-磷酸胆碱（POPC）在稀水溶液（10 mM磷酸盐缓冲液，154 mM NaCl，pH 7.4）中的相互作用。通过直角光散射和等温滴定量热法对囊泡溶解和重构、膜分配和胶束形成的热力学参数进行了评估。膜移位和溶解在25 ℃下进行得非常缓慢，但在65 ℃下显著加速。在此温度下，一个简单的SDS/POPC相图（包括囊泡，共存，胶束范围）和一套完整的分配系数和传递函数。在膜表面的静电排斥效应，通过结合Gouy-Chapman理论与Langmuir吸附等温线来解释Na+结合到膜结合的DS-。这种方法提供了一个定量的溶解和重建过程，这是解释在分配平衡和理想的混合在所有阶段。因此，在给定的实验条件下，跨双层翻转速率比任何其他性质更能决定洗涤剂对化学控制的脂质膜溶解和重构的适用性。
We provide a comprehensive thermodynamic description of lipid membrane dissolution by a charged detergent. To this end, we have studied the interactions between the anionic detergent sodium dodecyl sulfate ( SDS) and the zwitterionic phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine ( POPC) in dilute aqueous solution ( 10mM phosphate buffer, 154 mM NaCl, pH 7.4). Thermodynamic parameters of vesicle solubilization and reconstitution, membrane partitioning, and micelle formation were assessed by right-angle light scattering and isothermal titration calorimetry. Membrane translocation and dissolution proceed very slowly at 25 degrees C but are considerably accelerated at 65 degrees C. At this temperature, a simple SDS/POPC phase diagram ( comprising vesicular, coexistence, and micellar ranges) and a complete set of partition coefficients and transfer enthalpies were obtained. Electrostatic repulsion effects at the membrane surface were implemented by combining Gouy-Chapman theory with a Langmuir adsorption isotherm to account for Na+ binding to membrane-incorporated DS-. This approach offered a quantitative understanding of solubilization and reconstitution processes, which were interpreted in terms of partition equilibria between and ideal mixing in all phases. More than any other property, the transbilayer flip-flop rate under given experimental conditions hence appears to dictate a detergent's suitability for thermodynamically controlled lipid membrane solubilization and reconstitution.