Q. 13.76 - An Introduction to General, Organic, and Biological Chemistry

Question

The disaccharide trehalose found in mushrooms is composed of two $\alpha$-D-glucose molecules joined by an $\alpha (1\to 1)$-glycosidic bond. Draw the Haworth structure for trehalose. (13.4,13.6)

Step-by-Step Solution

Answer

Trehalose is a non-reducing disaccharide that is made up of two -glucose molecules joined by a 1,1-glycosidic bond. The enzyme trehalase in the colon digests this saccharide, releasing glucose for absorption.

Step 1: Introduction

Trehalose is a sugar that may be found in bacteria, fungus, yeast, insects, and plants.

Step 2: Draw the Haworth structure for glucose.

• We know the structure of glucose, and $\alpha$-glucose means that the anomeric carbon (carbon produced from the open-chain version of the carbohydrate molecule's carbonyl carbon component) has the OH group on the opposite side ${\mathrm{CH}}_2\mathrm{OH}$.

Step 3: Draw the Haworth structure for trehalose.

• Trehalose is a disaccharide formed from two molecules of glucose and connected by a $\mathrm{\alpha }-1,1$glycosidic bond.
• This means that both molecules of glucose are connected through the anomeric carbons which have the acetal oxygen (oxygen connecting two molecules of glucose) on the opposite sides from  ${\mathrm{CH}}_2\mathrm{OH}$ groups.