Pressure-jump X-ray studies of liquid crystal transitions in lipids
Pressure-jump X-ray studies of liquid crystal transitions in lipids
复制标题
脂质中液晶转变的压力跳跃 X 射线研究
DOI：
10.1098/rsta.2006.1844
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
R. Templer
中科院分区：
文献类型：
--
作者：
J. Seddon;A. Squires;C. Conn;O. Ces;A. Heron;X. Mulet;G. Shearman;R. Templer
在本文中，我们通过静态和时间分辨 X 射线衍射对反立方相和脂质中的相变进行了研究。在§1中，我们简要讨论了脂质的溶致相行为，重点关注非层状结构及其与脂质膜融合过程的几何/拓扑关系。还概述了不同立方相之间转变的可能途径。在第 2 节中，我们讨论了静水压对脂质膜和脂质相变的影响，并描述了如何方便地测量预测脂质相变温度的压力依赖性所需的参数。我们回顾了我们实验室的一些反双连续立方相的早期结果，显示了压力诱导形成和膨胀等效应。在第 3 节中，我们描述了压跃同步加速器 X 射线衍射技术。我们提出了从脂质系统 1 : 2 二月桂酰磷脂酰胆碱/月桂酸立方-逆六方、立方-立方和层状-立方转变中获得的结果。发现转变速率随着压力跃变的幅度和温度的升高而增加。还获得了过渡过程中短暂发生的中间结构的证据。在第 4 节中，我们描述了我们实验室正在开发的基于 IDL 的“AXcess”软件包，该软件包允许对压跃同步加速器实验产生的大型 X 射线数据集进行批量处理和分析。在§5中，我们介绍了单链脂质1-单油苷的流体层状-Pn3m立方相变的一些最新结果，我们通过压力跳跃和温度跳跃X射线衍射对其进行了研究。最后，在第 6 节中，我们给出了本研究未来方向的一些指标。我们预计最有用的技术进步将是微秒时间尺度的压力跳跃装置的开发，这将涉及使用一堆压电压力执行器。压力跳跃技术不仅限于脂质相变，还可以用于研究各种软物质转变，从蛋白质解折叠和 DNA 解旋和转变，到热致液晶、表面活性剂和嵌段共聚物中的相变。
In this paper, we give an overview of our studies by static and time-resolved X-ray diffraction of inverse cubic phases and phase transitions in lipids. In §1, we briefly discuss the lyotropic phase behaviour of lipids, focusing attention on non-lamellar structures, and their geometric/topological relationship to fusion processes in lipid membranes. Possible pathways for transitions between different cubic phases are also outlined. In §2, we discuss the effects of hydrostatic pressure on lipid membranes and lipid phase transitions, and describe how the parameters required to predict the pressure dependence of lipid phase transition temperatures can be conveniently measured. We review some earlier results of inverse bicontinuous cubic phases from our laboratory, showing effects such as pressure-induced formation and swelling. In §3, we describe the technique of pressure-jump synchrotron X-ray diffraction. We present results that have been obtained from the lipid system 1 : 2 dilauroylphosphatidylcholine/lauric acid for cubic–inverse hexagonal, cubic–cubic and lamellar–cubic transitions. The rate of transition was found to increase with the amplitude of the pressure-jump and with increasing temperature. Evidence for intermediate structures occurring transiently during the transitions was also obtained. In §4, we describe an IDL-based ‘AXcess’ software package being developed in our laboratory to permit batch processing and analysis of the large X-ray datasets produced by pressure-jump synchrotron experiments. In §5, we present some recent results on the fluid lamellar–Pn3m cubic phase transition of the single-chain lipid 1-monoelaidin, which we have studied both by pressure-jump and temperature-jump X-ray diffraction. Finally, in §6, we give a few indicators of future directions of this research. We anticipate that the most useful technical advance will be the development of pressure-jump apparatus on the microsecond time-scale, which will involve the use of a stack of piezoelectric pressure actuators. The pressure-jump technique is not restricted to lipid phase transitions, but can be used to study a wide range of soft matter transitions, ranging from protein unfolding and DNA unwinding and transitions, to phase transitions in thermotropic liquid crystals, surfactants and block copolymers.
影响因子：
2.9
作者：
CAFFREY, M
通讯作者：
CAFFREY, M
影响因子：
14
作者：
Qiu, H;Caffrey, M
通讯作者：
Caffrey, M