Reyes Mateo C, Tauc P, Brochon J C
Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Centre National de la Recherche Scientifique-Ministere de l'Education Nationale-Commissariat à l'Energie Atomique, Université Paris Sud, Orsay, France.
Biophys J. 1993 Nov;65(5):2248-60. doi: 10.1016/S0006-3495(93)81258-X.
The effects of hydrostatic pressure on the physical properties of large unilamellar vesicles of single lipids dipalmitoyl phosphatidylcholine (DPPC) and dimyristoyl phosphatidylcholine (DMPC) and lipid mixtures of DMPC/DPPC have been studied from time-resolved fluorescence of trans-parinaric acid. Additional experiments were carried out using diphenylhexatriene to compare the results extracted from both probes. Fluorescence decays were analyzed by the maximum entropy method. Pressure does not influence the fluorescence lifetime distribution of trans-parinaric acid in isotropic solvents. However, in pressurized lipid bilayers an abrupt change was observed in the lifetime distribution which was associated with the isothermal pressure-induced phase transition. The pressure to temperature equivalence values, dT/dP, determined from the midpoint of the phase transitions, were 24 and 14.5 degrees C kbar-1 for DMPC and POPC, respectively. Relatively moderate pressures of about 500 bar shifted the DMPC/DPPC phase diagram 11.5 degrees C to higher temperatures. The effects of pressure on the structural properties of these lipid vesicles were investigated from the anisotropy decays of both probes. Order parameters for all systems increased with pressure. In the gel phase of POPC the order parameter was smaller than that obtained in the same phase of saturated phospholipids, suggesting that an efficient packing of the POPC hydrocarbon chains is hindered.
通过反式紫黄质的时间分辨荧光研究了静水压力对单脂质二棕榈酰磷脂酰胆碱（DPPC）和二肉豆蔻酰磷脂酰胆碱（DMPC）以及DMPC/DPPC脂质混合物的大单层囊泡物理性质的影响。使用二苯基己三烯进行了额外的实验，以比较从两种探针提取的结果。通过最大熵方法分析荧光衰减。压力不影响反式紫黄质在各向同性溶剂中的荧光寿命分布。然而，在加压的脂质双层中，观察到寿命分布发生突然变化，这与等温压力诱导的相变有关。从相变中点确定的压力与温度等效值dT/dP，DMPC和POPC分别为24和14.5℃/kbar-1。约500 bar的相对中等压力使DMPC/DPPC相图向更高温度移动了11.5℃。从两种探针的各向异性衰减研究了压力对这些脂质囊泡结构性质的影响。所有系统的序参数随压力增加。在POPC的凝胶相中，序参数小于在饱和磷脂相同相中获得的序参数，这表明POPC烃链的有效堆积受到阻碍。
