Baenziger J U, Fiete D
J Biol Chem. 1979 Feb 10;254(3):789-95.
The complete structure of the complex oligosaccharides of fetuin has been established. The three fractions of complex oligosaccharide which were isolated by ion exchange chromatography following pronase digestion (F-I, F-II, and F-III) had identical molar ratios of sialic acid (Sia), galactose, mannose, and N-acetylglucosamine of 3:3:3:5. A combination of methylation analyses, Smith periodate degradations, and endoglycosidase and exoglycosidase digestions were utilized to establish the structure which is proposed to be: (see article of journal). Features of this structure not previously established include the presence of 2 residues of alpha2,3- and 1 residue of alpha2,6-linked sialic acid and their location relative to the mannose branch points. Also unusual is the presence of an alpha-linked branch mannose with substituents at positions 2 and 4 which is in turn linked to position 6 of the beta-linked, branch mannose. These features result in unexpected resistance to specific exoglycosidases.
胎球蛋白复合寡糖的完整结构已被确定。在链霉蛋白酶消化后通过离子交换色谱法分离得到的复合寡糖的三个组分（F-I、F-II和F-III），其唾液酸（Sia）、半乳糖、甘露糖和N-乙酰葡糖胺的摩尔比相同，均为3:3:3:5。采用甲基化分析、高碘酸史密斯降解、内切糖苷酶和外切糖苷酶消化相结合的方法来确定其结构，该结构被认为是：（见期刊文章）。此结构中先前未确定的特征包括存在2个α2,3连接的唾液酸残基和1个α2,6连接的唾液酸残基，以及它们相对于甘露糖分支点的位置。同样不寻常的是存在一个α连接的分支甘露糖，其在2位和4位有取代基，该分支甘露糖又与β连接的分支甘露糖的6位相连。这些特征导致对特定外切糖苷酶具有意外的抗性。
