A glycosidic bond, also known as a glycosidic linkage, is a type of covalent ether bond that connects a carbohydrate (sugar) molecule to another group, which can be another carbohydrate or a different molecule such as an alcohol or nitrogen-containing compound

. This bond forms specifically between the anomeric carbon of a sugar (the carbon involved in the hemiacetal or hemiketal group) and the hydroxyl group (–OH) of another molecule

. Glycosidic bonds are formed through a condensation reaction, where one molecule of water is removed as the bond forms

. The reverse process, breaking the bond, is called hydrolysis and consumes one water molecule. There are different types of glycosidic bonds depending on the atom linking the sugar to the other group:

• O-glycosidic bonds : oxygen links the sugar to the other molecule (most common)

• S-glycosidic bonds : sulfur replaces oxygen.
• N-glycosidic bonds : nitrogen replaces oxygen, often found in nucleotides.
• C-glycosidic bonds : carbon replaces oxygen, which are more resistant to hydrolysis

Glycosidic bonds are crucial in biology as they connect monosaccharides to form disaccharides (e.g., maltose, sucrose) and polysaccharides (e.g., cellulose, starch), and are also present in important biomolecules like DNA, where the sugar is linked to nitrogenous bases via N-glycosidic bonds

. In summary, a glycosidic bond is a covalent linkage formed by condensation between the anomeric carbon of a sugar and a hydroxyl or other group, essential for constructing complex carbohydrates and glycoconjugates in living organisms