Myelin labeled with mercuric chloride. Asymmetric localization of phosphatidylethanolamine plasmalogen.
Myelin labeled with mercuric chloride. Asymmetric localization of phosphatidylethanolamine plasmalogen.
复制标题
髓磷脂用氯化汞标记。
DOI：
10.1016/0022-2836(82)90503-4
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发表时间：
1982
影响因子：
5.6
通讯作者：
Ganser,AL
中科院分区：
文献类型：
--
作者：
Kirschner,DA;Ganser,AL
我们已经记录了修改后的X射线衍射图案，以15毫米间距从用氯化汞（HgCl 2）在0.5至32毫米水或盐水浓度处理坐骨神经。观察到的变化，在重复周期和低阶反射的强度表明更紧密的包装膜在其细胞质表面用氯化汞处理后。此外，0.25 mmor以上的HgCl 2可防止细胞外边界处的水溶胀。通过比较不同条件下处理与氯化汞的神经的独特的衍射图案，我们解释了高阶X射线反射的强度的变化，并计算了电子密度分布的改性膜。用HgCl 2处理前后的膜轮廓之间最显着的差异是在双层的细胞质的一半中的脂质头基峰的区域中电子密度的大幅增加。这种增加的幅度和位置表明髓鞘脂质的标记。为了检验这种可能性，我们分析了汞处理的坐骨神经中的脂质。从用HgCl 2处理的神经中提取的脂质的薄层色谱显示磷脂酰乙醇胺的显著减少，磷脂酰乙醇胺主要以缩醛原的形式存在于髓鞘中。同时，出现一个新的斑点，经鉴定为溶血磷脂酰乙醇胺。通过用HgCl 2处理提取的脂质获得了相同的结果，这表明相同的相互作用位点存在于完整的膜中作为分散的脂质。先前对缩醛磷脂的研究表明，汞与α，β-不饱和醚基团的β-碳加成，生成溶血脂质和结合汞的醛（Norton，1959）。从我们的X-射线结构分析和化学研究的相关性，我们得出结论，磷脂酰乙醇胺缩醛磷脂优先定位在髓鞘膜双层的细胞质的一半。
We have recorded modified X-ray diffraction patterns to 15 Å spacing from sciatic nerves treated with mercuric chloride (HgCl2) at concentrations of 0.5 to 32 mmin water or in saline. The observed changes in repeat period and in the intensities of the low-order reflections indicate closer packing of membranes at their cytoplasmic surfaces after treatments with HgCl2. In addition, HgCl2at 0.25 mmor more prevents swelling in water at the extracellular boundaries. By comparing the distinctive diffraction patterns from nerves treated under different conditions with HgCl2, we have interpreted the changes in intensities of the higher order X-ray reflections and have calculated electron density profiles of the modified membranes. The most striking difference between membrane profiles before and after treatment with HgCl2is the large increase in electron density in the region of the lipid headgroup peak in the cytoplasmic half of the bilayer. The magnitude and location of this increase suggests labeling of myelin lipid. To examine this possibility, we analyzed the lipids from mercury-treated sciatic nerves.Thin-layer chromatography of lipids extracted from nerves treated with HgCl2shows a marked decrease of phosphatidylethanolamine, which exists in myelin primarily as plasmalogen. At the same time, a new spot identified as lysophosphatidylethanolamine appears. An identical result was obtained by treating extracted lipids with HgCl2, suggesting that the same sites of interaction are present in the intact membrane as in the dispersed lipids. Previous studies on plasmalogens indicate that mercury adds to the β-carbon of the α,β-unsaturated ether group to produce a lyso-lipid and an aldehyde with bound mercury (Norton, 1959). From a correlation of our X-ray structural analysis and the chemical studies, we conclude that phosphatidylethanolamine plasmalogen is preferentially localized in the cytoplasmic half of the myelin membrane bilayer.