Kalina M, Pease D C
J Cell Biol. 1977 Sep;74(3):742-6. doi: 10.1083/jcb.74.3.742.
Unsaturated natural and synthetic phosphatidyl cholines (PCs), when treated with tannic acid and OsO4, demonstrated a substantial increase in contrast as compared to PC treated only with OsO4. This was not observed when phosphatidyl ethanolamine (PEA) was similarly exposed to tannic acid. The increased electron density observed in the lamellar organization of the PC phospholipids was limited to the hydrophilic layers corresponding to the polar regions of the phospholipid molecules. The repeating periods of lamellae were identical in PC, treated with both tannic acid and OsO4, and when treated only with OsO4. In each case, this approximated 45 A. The enhancement of membrane contrast by tannic acid in the presence of OsO4 is interpreted as being at least in part due to its multivalent capacity, binding to reactive sites on choline, as well as with OsO4.
不饱和天然和合成磷脂酰胆碱（PCs）在用单宁酸和四氧化锇处理后，与仅用四氧化锇处理的PC相比，对比度显著增加。当磷脂酰乙醇胺（PEA）以类似方式暴露于单宁酸时，未观察到这种情况。在PC磷脂的层状结构中观察到的电子密度增加仅限于与磷脂分子极性区域相对应的亲水层。用单宁酸和四氧化锇处理的PC以及仅用四氧化锇处理的PC中，片层的重复周期是相同的。在每种情况下，这一数值约为45埃。在四氧化锇存在下，单宁酸对膜对比度的增强被解释为至少部分归因于其多价能力，即与胆碱上的反应位点以及与四氧化锇结合。
