20. Carbohydrates

 What are the disaccharides and polysaccharides present in each of the following?

a. <IMAGE>

The glycosidic bond in a disaccharide was determined to be α(1→6). Hydrolysis of the disaccharide produced one galactose and one fructose. Draw the structure of the disaccharide.

The structure of sucralose, found in the artificial sweetener Splenda, is shown in the figure. It consists of a chlorinated disaccharide made up of galactose and fructose. In its structure shown,

(a) identify the galactose unit and the fructose unit.

Trehalose is a naturally occurring disaccharide used in cosmetics because of its ability to retain moisture. The formal name of trehalose is glucose α, α(1→1) glucose. Draw the structure of trehalose. Is it a reducing or nonreducing sugar?

Write the products for the following condensation or hydrolysis reactions:

a.

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