A temperature gradient method for lipid phase diagram construction using time-resolved x-ray diffraction.
A temperature gradient method for lipid phase diagram construction using time-resolved x-ray diffraction.
复制标题
使用时间分辨 X 射线衍射构建脂质相图的温度梯度方法。
DOI：
10.1016/s0006-3495(87)83309-x
复制
发表时间：
1987
影响因子：
3.4
通讯作者：
Hing,FS
中科院分区：
文献类型：
--
作者：
Caffrey,M;Hing,FS
描述并评估了一种能够以前所未有的速度构建温度组成相图的方法。该方法涉及沿金属棒的长度建立已知的温度梯度。将包含在长薄壁毛细管中的不同成分的样品纵向放置在杆上并“平衡”，以便将温度梯度传递到样品中。然后，样品移动通过聚焦的、单色同步子衍生的 X 射线束，样品的图像增强衍射图案会实时记录在录像带上，作为位置和温度的函数。衍射图案发生变化的温度对应于相边界，并且可以基于衍射图案识别存在（共存）于边界两侧的相。对覆盖整个成分范围的样品重复测量即可完成相图。这些额外的样品可以方便地放置在圆柱棒周边的不同位置，并旋转到衍射测量的位置。使用新的温度梯度方法构建了完全水合的二元混合物二肉豆蔻酰磷脂酰胆碱（DMPC）/二棕榈酰磷脂酰胆碱（DPPC）和二棕榈酰磷脂酰乙醇胺（DPPE）/DPPC的温度组成相图。它们与其他技术获得的结果非常一致并得到了扩展。在 DPPE/DPPC 系统中，报告了包括亚凝胶相在内的各个相中作为温度函数的结构参数。讨论了这种稳态方法的潜在局限性。
A method that enables temperature-composition phase diagram construction at unprecedented rates is described and evaluated. The method involves establishing a known temperature gradient along the length of a metal rod. Samples of different compositions contained in long, thin-walled capillaries are positioned lengthwise on the rod and "equilibrated" such that the temperature gradient is communicated into the sample. The sample is then moved through a focused, monochromatic synchroton-derived x-ray beam and the image-intensified diffraction pattern from the sample is recorded on videotape continuously in live-time as a function of position and, thus, temperature. The temperature at which the diffraction pattern changes corresponds to a phase boundary, and the phase(s) existing (coexisting) on either side of the boundary can be identified on the basis of the diffraction pattern. Repeating the measurement on samples covering the entire composition range completes the phase diagram. These additional samples can be conveniently placed at different locations around the perimeter of the cylindrical rod and rotated into position for diffraction measurement. Temperature-composition phase diagrams for the fully hydrated binary mixtures, dimyristoylphosphatidylcholine (DMPC)/dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine (DPPE)/DPPC, have been constructed using the new temperature gradient method. They agree well with and extend the results obtained by other techniques. In the DPPE/DPPC system structural parameters as a function of temperature in the various phases including the subgel phase are reported. The potential limitations of this steady-state method are discussed.