1.1.5 The Glycosidic Bond

• For example, in maltose, two glucose molecules join together to form a glycosidic bond, resulting in a disaccharide.

• In sucrose, a glycosidic bond forms between α-glucose and β-fructose to create another disaccharide.

  

• In polysaccharides like amylopectin, many glycosidic bonds connect glucose molecules, forming long, branched chains. Glycosidic bonds make sugar molecules more suitable for transport, storage, and they help reduce the osmolarity of cells, preventing water balance issues.

Breaking the Glycosidic Bond

The glycosidic bond can be broken through a process called hydrolysis, where a water molecule is added to split the bond. This reaction breaks down larger sugar molecules, such as disaccharides and polysaccharides, back into their individual monosaccharides.

• Hydrolysis is important in processes like digestion, where large carbohydrates are broken down into smaller sugars that can be absorbed by the body. For example, the breakdown of sucrose into glucose and fructose is an example of hydrolysis. Enzymes are required to catalyse both condensation and hydrolysis reactions.

Enzymes and Bond Types

Different types of monosaccharides form different types of glycosidic bonds, such as:

• Maltose has an α-1,4 glycosidic bond.
• Sucrose has an α-1,2 glycosidic bond. These bonds play an essential role in the structure and function of carbohydrates in biological systems, including energy storage (e.g., glycogen, starch) and structural components (e.g., cellulose).