Domains and anomalous adsorption isotherms of dipalmitoylphosphatidylcholine membranes and lipophilic ions: pentachlorophenolate, tetraphenylborate, and dipicrylamine.
Domains and anomalous adsorption isotherms of dipalmitoylphosphatidylcholine membranes and lipophilic ions: pentachlorophenolate, tetraphenylborate, and dipicrylamine.
复制标题
二棕榈酰磷脂酰胆碱膜和亲脂性离子的域和异常吸附等温线：五氯酚盐、四苯硼酸盐和二辛胺。
DOI：
10.1016/s0006-3495(91)82321-9
复制
发表时间：
1991
影响因子：
3.4
通讯作者：
Wang,S
中科院分区：
文献类型：
--
作者：
Smejtek,P;Wang,S
二棕榈酰磷脂酰胆碱(DPPC)囊泡在吸附带负电荷的五氯苯酚(PCP-)、亲脂性离子四苯基硼酸酯(TPhB-)和二苦胺(DPA-)时，表面带负电荷。我们通过测量不同温度(25-42℃)下DPPC囊泡的Zeta-电位随吸附离子浓度的变化，得到了(A)Zeta-电位等温线，(B)通过测量不同PCP-浓度下Zeta-电位的温度依赖性，研究了PCP-对凝胶-流体相变的影响。在25℃、32℃和34℃时，PCP-的Zeta电位等温线对应于其凝胶相膜的吸附。在42摄氏度时，Zeta电位等温线对应于流体相中的膜。McLaughlin和Harary(1977)提出的朗缪尔-斯特恩-格雷厄姆吸附模型很好地描述了这些吸附等温线。生物化学。15：1941-1948)。37℃时的Zeta电位等温线不符合单相吸附模型。我们还观察到亲脂离子TPhB-和DPA-在低至25℃的温度下的异常吸附等温线，这些等温线表明DPPC膜由离子吸附驱动的凝胶-流体相变，在此过程中膜从弱吸附状态转变为强吸附状态。PCP-的反常等温线和Zeta-电位与温度的关系可用两相模型来描述：(A)各相的Langmuir-Stern-Grahame模型，(B)凝胶和流体区的共存，以及(C)PCP-降低凝胶-流体相变温度。在异常区域内，Zeta电位的大小迅速增加了吸附物种的浓度，这是用Esin-马尔可夫系数来表征的。这种效应可以在基于膜的设备中加以利用。并对PCP作为解偶联剂在能量传导膜中的可能作用进行了评述。
Dipalmitoylphosphatidylcholine (DPPC) vesicles acquire negative surface charge on adsorption of negatively charged pentachlorophenolate (PCP-), and lipophilic ions tetraphenylborate (TPhB-), and dipicrylamine (DPA-). We have obtained (a) zeta-potential isotherms from the measurements of electrophoretic mobility of DPPC vesicles as a function of concentration of the adsorbing ions at different temperatures (25–42 degrees C), and (b) studied the effect of PCP- on gel-to-fluid phase transition by measuring the temperature dependence of zeta-potential at different PCP- concentrations. The zeta-potential isotherms of PCP- at 25, 32, and 34 degrees C correspond to adsorption to membrane in its gel phase. At 42 degrees C the zeta-potential isotherm corresponds to membrane in its fluid phase. These isotherms are well described by a Langmuir-Stern-Grahame adsorption model proposed by McLaughlin and Harary (1977. Biochemistry. 15:1941–1948). The zeta-potential isotherm at 37 degrees C does not follow the single-phase adsorption model. We have also observed anomalous adsorption isotherms for lipophilic ions TPhB- and DPA- at temperatures as low as 25 degrees C. These isotherms demonstrate a gel-to-fluid phase transition driven by ion adsorption to DPPC membrane during which the membrane changes from weakly to a strongly adsorbing state. The anomalous isotherm of PCP- and the temperature dependence of zeta-potential can be described by a two-phase model based on the combination of (a) Langmuir-Stern-Grahame model for each phase, (b) the coexistence of gel and fluid domains, and (c) depression of gel-to-fluid phase transition temperature by PCP-. Within the anomalous region the magnitude of zeta-potential rapidly increases concentration of adsorbing species, which was characterized in terms of a Esin-Markov coefficient. This effect can be exploited in membrane-based devices. Comments are also made on the possible effect of PCP, as an uncoupler, in energy transducing membranes.