The structure of carbohydrate unit B of porcine thyroglobulin.
The structure of carbohydrate unit B of porcine thyroglobulin.
复制标题
猪甲状腺球蛋白碳水化合物单元 B 的结构。
作者：
K. Yamamoto;T. Tsuji;T. Irimura;T. Osawa
以猪甲状腺球蛋白为原料，采用肼解法制备低聚糖组分。采用DEAE-cellulose和concanavalin A-Sepharose色谱柱逐层纯化单位b型寡糖的4个组分，并结合内、外糖苷酶酶切、甲基化分析和Smith降解对其结构进行研究。根据这些研究结果，提出了B单元低聚糖的结构如下：见公式。因此发现糖蛋白具有三天线和双天线络合型寡糖作为酸性糖链。三触角寡糖的结构特征是：(1)唾液酸残基不局限于特定的分支上，而是分布在三个分支上；(2)然而，α(2 - 3)-连接的唾液酸残基仅位于分支α -甘露糖残基的C-4分支的末端，而α(2 - 6)-连接的唾液酸残基占据了其他分支的末端；(3)外支链α -甘露糖残基与内支链β -甘露糖残基的C-3或C-6相连，两种类型均存在。
The oligosaccharide fraction was obtained from porcine thyroglobulin by hydrazinolysis. Four fractions of unit B-type oligosaccharides were purified by successive chromatographies on columns of DEAE-cellulose and concanavalin A-Sepharose, and their structures were investigated by the combination of endo- and exo-glycosidase digestions, methylation analysis and Smith degradation. From the results of these studies, the structures of the unit B oligosaccharides were proposed to be as follows: see formula in text. Thus the glycoprotein was found to have triantennary and biantennary complex-type oligosaccharides as acidic sugar chains. Concerning the triantennary oligosaccharides, the following structural features were shown: (1) the sialic acid residues were not localized on certain specific branches but distributed on all three branches; (2) however, alpha (2 leads to 3)-linked sialic acid residues were exclusively located on the terminal of the branch arising from C-4 of the branching alpha-mannose residue, whereas alpha (2 leads to 6)-linked sialic acid residues occupied terminals of the other branches; (3) the outer branching alpha-mannose residue was attached to C-3 or C-6 of an inner branching beta-linked mannose residue, and both types were observed to exist.