Chapter 24.20, Problem 25P

Interpretation Introduction

Interpretation:

In anthrax spore tetrasaccharide, the glycosidic linkages between the carbohydrates are to be labelled.

Concept introduction:

In disaccharide or polysaccharide, the two or more sugar molecules are linked with glycosidic bond.

The bond formed between the anomeric carbon of one sugar molecule and the hydroxyl group of other sugar molecule is called glycosidic bond or glycosidic linkage.

The glycosidic linkage can be labelled by the stereochemistry at anomeric carbon as $\text{α}\text{or β}$ and carbon’s number which involves in the linkage between two sugar molecules.

The stereoisomer belongs to $\text{D}$ series when the hydroxyl group at the highest-numbered chirality center is down in Haworth formula.

The stereoisomer belongs to $\text{L}$ series when the hydroxyl group at the highest-numbered chirality center is up in Haworth formula.

For the $\text{D}$ series of carbohydrates, if the hydroxyl group at anomeric carbon is down, the configuration at that carbon is $\text{α}$, and if the hydroxyl group is up, the configuration at anomeric carbon is $\text{β}$.

For the $\text{L}$ series of carbohydrates, if the hydroxyl group at anomeric carbon is down, the configuration at that carbon is $\text{β}$ and if the hydroxyl group is up, the configuration at anomeric carbon is $\text{α}$.

In a Fischer projection, the substituents to the right are down and those to the left are up in the corresponding Haworth formula.