Westhead E W, Winkler H
Neuroscience. 1982 Jul;7(7):1611-4. doi: 10.1016/0306-4522(82)90018-5.
We have studied the topography of the gangliosides of the adrenal chromaffin granules by using neuraminidase to remove sialic acid from membrane gangliosides of intact and ruptured chromaffin granules. Residual sialic acid was then measured to compare the availability of gangliosides on the outer and inner surfaces of the membrane. Measurement of protein sialic acid served as a control since these residues are known to be on the inner surface of the membrane. Prolonged digestion of broken membranes showed that maximally 75% of both lipid and protein-bound sialic acid residues are available to neuraminidase. Prolonged digestion of intact granules produced no measureable loss of sialic acid from either protein or lipid fractions. Comparison of the thin-layer chromatograms of gangliosides extracted from digested and undigested membranes showed no preferential digestion of any component. We conclude that at least 75% of the gangliosides are on the inner leaflet of the membrane and suggest that all of the gangliosides are so located.
我们通过使用神经氨酸酶从完整和破裂的嗜铬颗粒的膜神经节苷脂中去除唾液酸，研究了肾上腺嗜铬颗粒神经节苷脂的拓扑结构。然后测量残留的唾液酸，以比较膜内外表面神经节苷脂的可及性。蛋白质唾液酸的测量作为对照，因为已知这些残基位于膜的内表面。对破碎膜的长时间消化表明，最大75%的脂质和蛋白质结合的唾液酸残基可被神经氨酸酶作用。对完整颗粒的长时间消化未导致蛋白质或脂质部分的唾液酸有可测量的损失。比较从消化和未消化膜中提取的神经节苷脂的薄层色谱图，未发现任何成分有优先消化现象。我们得出结论，至少75%的神经节苷脂位于膜的内小叶，并认为所有神经节苷脂都位于此处。
