Ravindranath M H, Higa H H, Cooper E L, Paulson J C
J Biol Chem. 1985 Jul 25;260(15):8850-6.
A sialic acid-binding lectin with high specificity for 9-O-acetyl- and 4-O-acetylsialic acids was purified from the hemolymph of the California coastal crab, Cancer antennarius, by affinity chromatography using bovine submaxillary mucin coupled to agarose. The binding specificity of the crab lectin distinguishes it from other known sialic acid-specific lectins from Limulus polyphemus and Limax flavus which show a broader range of specificity for sialic acids. The purified lectin is homogenous on sodium dodecyl sulfate-polyacrylamide electropherograms with a subunit molecular weight of about 36 kDa. The specificity of the lectin for O-acetylsialic acids appears to account for the fact that it agglutinates mouse, rat, rabbit, and horse erythrocytes, which contain O-acetylsialic acids on cell surface glycoconjugates, but not human monkey, sheep, goat, and chicken erythrocytes which contain only NeuAc or N-glycolylneuraminic acid (NeuGc). This conclusion was supported by the potent inhibition of hemagglutination by bovine and equine submaxillary mucins which contain 9(7,8)-O-acetyl- and 4-O-acetylsialic acids, respectively, and also by free 9-O-acetyl-N-acetylneuraminic acid (9-O-Ac-NeuAc) and 4-O-Ac-NeuAc relative to NeuAc and NeuGc. Further support for the role of O-Ac-sialic acids in hemagglutination of erythrocytes was obtained by enzymatic modification of human erythrocytes. Sialidase-treated erythrocytes were resialylated with purified sialyltransferases and various CMP-sialic acid donor substrates to contain NeuAc or NeuGc or 9-O-Ac-NeuAc in the Sia alpha 2,3Gal or Sia alpha 2,6Gal linkages. Cells resialylated to contain NeuAc or NeuGc were not agglutinated, but cells resialylated to contain 9-O-Ac-NeuAc were agglutinated with high titer, comparable to that of mice or horse erythrocytes.
通过使用偶联到琼脂糖上的牛下颌粘蛋白进行亲和色谱，从加利福尼亚沿海蟹（Cancer antennarius）的血淋巴中纯化出一种对9 - O - 乙酰基唾液酸和4 - O - 乙酰基唾液酸具有高特异性的唾液酸结合凝集素。蟹凝集素的结合特异性使其与来自鲎（Limulus polyphemus）和黄蛞蝓（Limax flavus）的其他已知唾液酸特异性凝集素区分开来，后两者对唾液酸显示出更广泛的特异性范围。纯化的凝集素在十二烷基硫酸钠 - 聚丙烯酰胺电泳图谱上是均一的，亚基分子量约为36 kDa。凝集素对O - 乙酰基唾液酸的特异性似乎解释了它能凝集小鼠、大鼠、兔和马的红细胞这一事实，这些红细胞在细胞表面糖缀合物上含有O - 乙酰基唾液酸，而不能凝集仅含有NeuAc或N - 羟乙酰神经氨酸（NeuGc）的人、猴、绵羊、山羊和鸡的红细胞。这一结论得到了牛和马下颌粘蛋白对血凝的有效抑制的支持，它们分别含有9(7,8) - O - 乙酰基和4 - O - 乙酰基唾液酸，以及相对于NeuAc和NeuGc的游离9 - O - 乙酰基 - N - 乙酰神经氨酸（9 - O - Ac - NeuAc）和4 - O - Ac - NeuAc。通过对人红细胞的酶促修饰，进一步支持了O - 乙酰基唾液酸在红细胞血凝中的作用。用纯化的唾液酸转移酶和各种CMP - 唾液酸供体底物对经唾液酸酶处理的红细胞进行再唾液酸化，使其在Siaα2,3Gal或Siaα2,6Gal连接中含有NeuAc或NeuGc或9 - O - Ac - NeuAc。再唾液酸化后含有NeuAc或NeuGc的细胞未被凝集，但再唾液酸化后含有9 - O - Ac - NeuAc的细胞以高滴度被凝集，与小鼠或马红细胞的滴度相当。
