Boehler B A, De Gier J, Van Deenen L L
Biochim Biophys Acta. 1978 Oct 4;512(3):480-8. doi: 10.1016/0005-2736(78)90158-x.
The permeation of water through liposomal membranes composed of various saturated phosphatidylcholine plus gramicidin A was studied as a function of temperature. 1. The presence of gramicidin in the liposomal bilayers caused an increase in water permeability. Below the phase transition temperature this effect could be measured quite clearly in all the systems we tested, but the extent of the increase was largely dependent on the length of the hydrocarbon chains. 2. Increasing amounts of gramicidin caused a gradual disappearance of the abrupt change in the rate of water permeation near the gel-liquid crystalline phase transition temperature of dipalmitoyl phosphatidylcholine liposomes. Differential scanning calorimetry analysis of the system containing these relatively small amounts of gramicidin still showed a clear transition from the liquid crystalline to the gel state with only a slight reduction in the enthalpy change. 3. In liposomes composed of dimyristoyl, dipalmitoyl and saturated egg phosphatidylcholine there was a concomitant decrease in the activation energy of water permeation in the presence of gramicidin below and above the phase transition temperature. The activation energy for water permeation through longer chained distearoyl phosphatidylcholine liposomal bilayers was the same with or without gramicidin in the bilayer. 4. It is concluded that the ability of gramicidin to form conducting channels in a gel state bilayer depends on the thickness of the paraffin core.
研究了水通过由各种饱和磷脂酰胆碱加短杆菌肽A组成的脂质体膜的渗透情况，并将其作为温度的函数进行研究。1. 脂质体双层中短杆菌肽的存在导致水渗透性增加。在相变温度以下，在我们测试的所有系统中都能很清楚地测量到这种效应，但增加的程度在很大程度上取决于烃链的长度。2. 短杆菌肽含量的增加导致二棕榈酰磷脂酰胆碱脂质体在凝胶-液晶相变温度附近水渗透速率的突然变化逐渐消失。对含有这些相对少量短杆菌肽的系统进行差示扫描量热分析仍显示出从液晶态到凝胶态的明显转变，只是焓变略有降低。3. 在由二肉豆蔻酰、二棕榈酰和饱和卵磷脂组成的脂质体中，在相变温度以下和以上存在短杆菌肽时，水渗透的活化能都随之降低。通过较长链的二硬脂酰磷脂酰胆碱脂质体双层的水渗透活化能在双层中有或没有短杆菌肽时是相同的。4. 得出的结论是，短杆菌肽在凝胶态双层中形成传导通道的能力取决于石蜡核心的厚度。
