What is glycosidic linkage?

A glycosidic linkage is a type of chemical bond that connects two sugar molecules (monosaccharides) together to form a larger carbohydrate molecule, such as a disaccharide or a polysaccharide. This linkage involves the reaction between the hydroxyl (OH) group of one sugar molecule and the anomeric carbon atom (the carbon containing the carbonyl group, usually a ketone or an aldehyde) of another sugar molecule. The resulting covalent bond is called a glycosidic bond.

The process of forming a glycosidic linkage involves the removal of a water molecule (dehydration or condensation reaction) and results in the formation of an oxygen bridge between the two sugar molecules. The specific type of glycosidic linkage, as well as the orientation of the anomeric carbon (alpha or beta configuration), can vary depending on the arrangement of the participating sugar molecules.

Glycosidic linkages play a crucial role in the structure and function of various carbohydrates found in living organisms. For example, the disaccharide sucrose (table sugar) consists of glucose and fructose molecules linked together by a glycosidic linkage. Similarly, the polysaccharide cellulose, which forms the structural component of plant cell walls, is made up of glucose molecules connected by glycosidic linkages.

The arrangement of glycosidic linkages and the types of sugar molecules involved greatly influence the physical properties and functions of carbohydrates in biological systems.