磷脂单分子膜普适状态方程研究

从现有的磷脂单分子膜状态方程入手, 以磷脂临界相变面积(A_c)和相变温度(T_c)为参比, 引入对比面积(A_r), 对比温度(T_r), 并通过分析磷脂分子间作用力和底液分子与磷脂分子间作用力的影响, 提出了第三参数——相对铺展因子的概念, 导出了磷脂单分子膜普适状态方程. 运用1,2-二豆蔻酰基-sn-丙三基-3-磷脂酸, 1,2-二豆蔻酰基-sn-丙三基-3-磷脂酰胆碱, 1,2-二棕榈酰基-sn-丙三基-3-磷脂酰胆碱等磷脂单分子膜的实验数据进行一致性校验的结果表明, 该模型在扩展膜(LE)直至凝聚膜(LC)的整个区域均能较好地描述磷脂单分子膜的π-A曲线. 所获得的各磷脂的相对铺展因子绝对值直接表明了该物质的成膜特性.

Generalization of Surface State Equation for Phospholipid Monolayer

Based on the available surface state equation for phospholipid monolayers, a generalized equation was derived by introducing a third parameter—comparative expanding factor. It was supposed that the phospholipid monolayer surface characteristics have the close relation with not only the interaction between lipid intermolecules, but also the interaction between subsolution molecules and lipid ones. Therefore the third parameter—comparative expanding factor was defined as the ratio of the two interactions. Associating the reduced temperature T_r (based on the phase transition temperature T_c) and the reduced molecular area A_r (based on the molecular area of the liquid condensed film A_c) with the third parameter, the surface state equation was generalized to relate the π-A isotherm data of 1,2-dimyristoyl-sn-glycero-3-phosphocho- line, 1,2-dimyristoyl-sn-glycero-3-phosphatidic acid, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine with small errors. The results show that the generalized state equation could describe the surface characteristics of phospholipid monolayer during the expansion-compression circulation, and the data of the third parameter might reflect the rates of different phospholipids expanding to monolayers.