Wu S S, Lee A C, Bush C A
Biochim Biophys Acta. 1987 Jun 22;924(3):420-31. doi: 10.1016/0304-4165(87)90156-5.
Treatment of a blood group A-active ovarian cyst mucin glycoprotein with alkaline borohydride under conditions expected to cleave O-glycosidic linkages between carbohydrate and peptide releases a sulfated polysaccharide of average molecular weight 20,000. Its peptide and mannose content is less than 1%, and carbohydrate analysis gives Fuc/GalNAc/Gal/GlcNAc in the ratio of 1:1:2.2:2.2. Galactosaminitol is recovered at the level of one residue per 112-residue average polysaccharide chain. The 13C- and 1H-NMR spectra show that the polysaccharide has side chains whose non-reducing terminals have the blood group A structure on a type 1 chain: (Formula: see text). Methylation analysis confirms the presence of these blood group A type 1 sidechains as well as 4-substituted GlcNAc, 3-substituted galactose and 3,6-substituted galactose branch points. Periodate oxidation removes all the fucose and GalNAc from the non-reducing terminal but leaves intact the backbone composed of beta-linked Gal and GlcNAc, as would be expected for a polylactosamine. Although the native polysaccharide is resistant to endo-beta-galactosidase digestion, the product of periodate degradation is partially digested, giving a 30% yield of a trisaccharide shown by 1H-NMR spectroscopy to be: Gal(beta 1----3)GlcNAc(beta 1----3)Gal We conclude that this is a high molecular weight sulfated polysaccharide which is related to the asparagine-linked polylactosamine chains of cell surface glycoproteins which have been implicated in cell differentiation. However, the blood group A polysaccharide from the ovarian cyst mucin is unique in several respects. It is linked to the protein by an O-glycosidic bond rather than the N-asparagine linkage of the previously known polylactosamines which have a trimannosyl core, and its blood group A side chains are on a type 1 core rather than type 2 which is found on other polylactosamines.
在预期能裂解碳水化合物与肽之间 O-糖苷键的条件下，用碱性硼氢化物处理具有 A 血型活性的卵巢囊肿粘蛋白糖蛋白，可释放出平均分子量为 20,000 的硫酸化多糖。其肽和甘露糖含量低于 1%，碳水化合物分析得出岩藻糖/ N-乙酰半乳糖胺/半乳糖/ N-乙酰葡糖胺的比例为 1:1:2.2:2.2。每 112 个残基的平均多糖链中可回收一个残基水平的半乳糖胺醇。13C 和 1H NMR 光谱表明，该多糖具有侧链，其非还原末端在 1 型链上具有 A 血型结构：（分子式：见正文）。甲基化分析证实存在这些 A 血型 1 型侧链以及 4-取代的 N-乙酰葡糖胺、3-取代的半乳糖和 3,6-取代的半乳糖分支点。高碘酸盐氧化从非还原末端除去了所有的岩藻糖和 N-乙酰半乳糖胺，但保留了由β-连接的半乳糖和 N-乙酰葡糖胺组成的主链，这正如聚乳糖胺所预期的那样。尽管天然多糖对内切β-半乳糖苷酶消化具有抗性，但高碘酸盐降解产物被部分消化，1H NMR 光谱显示三糖的产率为 30%，该三糖为：半乳糖(β1----3)N-乙酰葡糖胺(β1----3)半乳糖 我们得出结论，这是一种高分子量的硫酸化多糖，它与细胞表面糖蛋白中与天冬酰胺连接的聚乳糖胺链有关，这些链与细胞分化有关。然而，来自卵巢囊肿粘蛋白的 A 血型多糖在几个方面是独特的。它通过 O-糖苷键与蛋白质相连，而不是与先前已知的具有三甘露糖核心的聚乳糖胺的 N-天冬酰胺键相连，并且其 A 血型侧链在 1 型核心上，而不是在其他聚乳糖胺上发现的 2 型核心上。
