Diaz Segura E A, Duarte J H
Carbohydr Res. 1976 Dec;52:159-67. doi: 10.1016/s0008-6215(00)85956-x.
When the galactan from the albumen glands of the snail Strophocheilus oblongus was submitted to three Smith-degradation, the degraded polysaccharide, isolated in 6% yield, was much more linear. Methylation analysis showed that the Smith-degraded polysaccharide gave an increased percentage of 2,4,6-tri, decreased percentages of 2,3,4,6-tetra-and 2,4-di, and a large variation in the amount of 2,3,4-tri-O-methyl-D-galactose. The sugars in the polysaccharide which result in the formation of 2,3,4,6-tetra- and 2,3,4-tri-O-methyl-D-galactose are destoryed in subsequent degradation procedures. The above observations suggest that the degradation by periodate oxidation proceeds via non-reducing end-groups and though some internal residues that are exposed as the degradation proceeds. As a result of the overall process, new non-reducing end-groups are formed and new (1 leads to 6)-linked D-galactose residues are then exposed. The isolation of glycosides of low molecular weight supports the suggestion that the molecule, in the main, is sequentially degraded from the external layers.
将长形卷管螺蛋白腺中的半乳聚糖进行三次史密斯降解后，以6%的产率分离得到的降解多糖线性程度更高。甲基化分析表明，经史密斯降解的多糖中，2,4,6-三甲基-D-半乳糖的比例增加，2,3,4,6-四甲基-D-半乳糖和2,4-二甲基-D-半乳糖的比例降低，且2,3,4-三-O-甲基-D-半乳糖的量有很大变化。多糖中导致形成2,3,4,6-四甲基-D-半乳糖和2,3,4-三-O-甲基-D-半乳糖的糖在后续降解过程中被破坏。上述观察结果表明，高碘酸盐氧化降解是通过非还原端基进行的，并且在降解过程中一些内部残基会暴露出来。由于整个过程，形成了新的非还原端基，新的（1→6）连接的D-半乳糖残基随后暴露出来。低分子量糖苷的分离支持了这样的观点，即该分子主要是从外层开始依次降解的。
