Lactulose is a disaccharide used in the treatment of chronic constipation. Its formal name is galactose β(1→4) fructose.

(a) Draw the structure of lactulose.

Identify a disaccharide that fits each of the following descriptions:

(a) ordinary table sugar

Isomaltose, a disaccharide formed during caramelization in cooking, contains two glucose units bonded ⍺(1→6). Draw the structure of isomaltose.

Carbohydrates are abbreviated using a three-letter abbreviation followed by their glycosidic bond type. For example, maltose and sucrose can be written respectively as

Provide the structure for the O-type blood carbohydrate set given the following abbreviation:

L-Fucα (1→2) Galß(1→4)GlcNAc

What is the identity of the disaccharide below?

Draw a disaccharide of two cyclic mannose molecules attached by an α-1,4 glycosidic linkage. Explain why the glycosidic products in Problem 20.58 are not reducing sugars, but the product in this problem is a reducing sugar.

Lactose and maltose are reducing disaccharides, but sucrose is a nonreducing disaccharide. Explain.

Trehalose, a disaccharide found in the blood of insects, has the following structure. What simple sugars would you obtain on hydrolysis of trehalose? (Hint: Rotate one of the rings in your head or redraw it rotated.)