Biochemistry: Glycosides Formation

Types of Bonds and Glycosides

• A glycosidic bond is formed when the hydroxyl group of the anomeric carbon of a monosaccharide reacts with an OH or NH group of a second compound.

Antibiotics and Disaccharides

• Streptomycin, an antibiotic, contains glycosides.
• Sucrose is known as cane sugar and table sugar.
• Lactose, a reducing sugar, contains glucose and galactose and is present in milk.

Disaccharides and Hydrolysis

• Sucrose hydrolysis produces glucose and fructose.
• Maltose hydrolysis produces two glucose molecules.
• Lactose hydrolysis produces glucose and galactose.
• Cellobiose hydrolysis produces two glucose molecules.

Reducing Sugars

• Lactose is classified as a reducing sugar because the anomeric carbon of glucose is available for oxidation.
• Sucrose is not a reducing sugar because the anomeric carbons of both glucose and fructose are involved in the glycosidic bond.

Polysaccharides

• Cellulose cannot be digested and absorbed in the human body unlike starch because it has a β-1,4 glycosidic bond, which is difficult to break down.
• Amylose, a form of starch, is a helical-shaped polysaccharide made up of α-1,4 glycosidic bonds.
• Glycogen is the major storage form of carbohydrate (glucose) in animals because it is a branched polysaccharide that can be easily broken down to glucose molecules.
• Chitin is an unbranched heteropolysaccharide made up of repeating disaccharides.