Tomoaia-Cotişel M, Zsakó J, Chifu E, Quinn P J
Department of Physical Chemistry, University of Cluj-Napoca, Romania.
Biochem J. 1987 Dec 15;248(3):877-82. doi: 10.1042/bj2480877.
The collapse pressure at the air-water interface of monomolecular films of 1,2-distearoyl derivatives of phosphatidylcholine and digalactosyldiacylglycerol containing various proportions of the carotenoid astaxanthin was related to the composition of the monolayer. The results were analysed by using a regular-association approximation by which it is assumed that there is a stepwise formation of ABi-type associations where A and B represent the diacyl lipid and astaxanthin respectively and 1 less than or equal to i less than or equal to 6. This treatment provides an adequate description of the experimental data and permits calculation of equilibrium constants for the steps in complex-formation; each step is said to have the same equilibrium constant. The value for the collapse-surface-pressure increment associated with formation of ABi complexes was also derived. Calculated values of equilibrium constants and collapse-surface-pressure increments are greater for phosphatidylcholine/astaxanthin mixed monolayers than for digalactosyldiacylglycerol/astaxanthin mixed monolayers. These differences are discussed in terms of intermolecular interactions between components in the two systems.
含有不同比例类胡萝卜素虾青素的磷脂酰胆碱和二半乳糖二酰基甘油的1,2 - 二硬脂酰衍生物单分子膜在气 - 水界面的崩溃压力与单分子层的组成有关。通过使用正则缔合近似法对结果进行分析，该方法假定存在ABi型缔合的逐步形成，其中A和B分别代表二酰基脂质和虾青素，且1≤i≤6。这种处理方法对实验数据提供了充分的描述，并允许计算复合物形成步骤的平衡常数；据说每个步骤具有相同的平衡常数。还得出了与ABi复合物形成相关的崩溃表面压力增量的值。磷脂酰胆碱/虾青素混合单分子膜的平衡常数和崩溃表面压力增量的计算值比二半乳糖二酰基甘油/虾青素混合单分子膜的要大。根据两个系统中各组分之间的分子间相互作用对这些差异进行了讨论。
