Question

Trehalose is found in young mushrooms and is the chief carbohydrate in the blood of certain insects. Trehalose is a disaccharide consisting of two D-monosaccharide units, each joined to the other by an \(\alpha-1,1\)-glycosidic bond.

Short answer

Answer: Trehalose is a disaccharide composed of two D-glucose units connected by an alpha-1,1-glycosidic bond.

Step-by-step solution

Understanding disaccharides

A disaccharide is a sugar molecule composed of two monosaccharide units joined by a glycosidic bond. A common example of a disaccharide is sucrose, which is formed by combining one glucose unit with one fructose unit.

Defining D-monosaccharide units and their role in trehalose

D-monosaccharides are a class of monosaccharides (single sugar molecules) with the hydroxyl group (-OH) on the right side of the carbon furthest from the carbonyl group in their Fischer projection. In trehalose, the two D-monosaccharide units combine through a glycosidic bond, forming the disaccharide structure of trehalose. The D-monosaccharides found in trehalose are two molecules of D-glucose.

Explaining the alpha-1,1-glycosidic bond in trehalose

A glycosidic bond is formed between the anomeric carbon (carbon with a double bond to an oxygen atom) of one monosaccharide unit and the hydroxyl group of another monosaccharide. In trehalose, the two D-glucose units are connected via an alpha-1,1-glycosidic bond. Alpha refers to the anomeric configuration of glucose where the hydroxyl group (-OH) linked to the anomeric carbon (C1) is in the same plane as the CH2OH group on the last carbon atom (C6) in the Haworth projection. An alpha-1,1-glycosidic bond indicates that the two D-glucose units are connected through their respective carbon 1 (C1) atoms with an alpha configuration. In conclusion, trehalose is a disaccharide composed of two D-glucose units connected by an alpha-1,1-glycosidic bond. It is found in young mushrooms and serves as the chief carbohydrate in the blood of certain insects.