Korrel S A, Clemetson K J, Van Halbeek H, Kamerling J P, Sixma J J, Vliegenthart J F
Eur J Biochem. 1984 May 2;140(3):571-6. doi: 10.1111/j.1432-1033.1984.tb08140.x.
Glycocalicin (140 kDa), constituting the main part of glycoprotein Ib (160 kDa), was released from the human platelet membrane by the action of a Ca2+-dependent protease, present in the platelet cytoplasm and liberated during sonication of the platelet suspension. After activation of the protease by Ca2+, the sonicated platelet suspension was subjected to differential centrifugation. The supernatant was applied to a column of wheat germ agglutinin linked to Sepharose 4B; glycocalicin was eluted from the column with 2.5% (w/v) N-acetylglucosamine. Glycocalicin was found to contain 40% carbohydrate by weight, representing N- as well as O-glycosidically linked carbohydrate chains. The O-glycosidic chains were split off by alkaline cleavage in the presence of 3H-labelled NaBH4. The liberated 3H-labelled oligosaccharide-alditols were fractionated on a DEAE-Sephadex A-25 column. The structures of the oligosaccharide-alditols were investigated by 500-MHz 1H-NMR spectroscopy. The major compound was identified as NeuAc alpha(2----3)Ga1 beta(1----3)[NeuAc alpha(2----3)Ga1 beta(1----4)GlcNAc beta(1----6)]GalNAc-ol. Two minor compounds were found to be NeuAc alpha(2----3)Gal beta(1----3)[NeuAc alpha(2----6)]GalNAc-ol and NeuAc alpha(2----3)Gal beta(1----3)GalNAc-ol.
糖萼钙蛋白（140 kDa）是糖蛋白Ib（160 kDa）的主要组成部分，通过存在于血小板细胞质中且在血小板悬浮液超声处理过程中释放的一种Ca2+依赖性蛋白酶的作用，从人血小板膜上释放出来。在Ca2+激活蛋白酶后，对超声处理后的血小板悬浮液进行差速离心。将上清液应用于连接到琼脂糖4B的麦胚凝集素柱；用2.5%（w/v）的N-乙酰葡糖胺从柱上洗脱糖萼钙蛋白。发现糖萼钙蛋白按重量计含有40%的碳水化合物，代表N-连接以及O-连接的碳水化合物链。在3H标记的NaBH4存在下，通过碱性裂解将O-糖苷链切断。释放出的3H标记的寡糖糖醇在DEAE-葡聚糖A-25柱上进行分级分离。通过500 MHz 1H-NMR光谱研究寡糖糖醇的结构。主要化合物被鉴定为NeuAcα(2→3)Galβ(1→3)[NeuAcα(2→3)Galβ(1→4)GlcNAcβ(1→6)]GalNAc-ol。发现两种次要化合物为NeuAcα(2→3)Galβ(1→3)[NeuAcα(2→6)]GalNAc-ol和NeuAcα(2→3)Galβ(1→3)GalNAc-ol。
