O-glycosidic bond

Definition

An o-glycosidic bond is a type of covalent bond that forms between a carbohydrate (sugar) and an alcohol or another carbohydrate, where the oxygen atom of the alcohol or sugar is involved in the linkage. This bond is crucial in forming disaccharides, oligosaccharides, and polysaccharides, playing a significant role in the structure and function of carbohydrates in biological systems.

5 Must Know Facts For Your Next Test

1. O-glycosidic bonds can be classified into two types: α (alpha) and β (beta), depending on the orientation of the hydroxyl group on the anomeric carbon during bond formation.
2. These bonds are formed through a condensation reaction, where a molecule of water is released as the bond is established between the hydroxyl group and the anomeric carbon.
3. O-glycosidic bonds contribute to the structural diversity of carbohydrates, leading to different properties and functions in biological systems.
4. Enzymes known as glycosidases can hydrolyze o-glycosidic bonds, which is essential for carbohydrate metabolism in organisms.
5. The stability of o-glycosidic bonds can vary; for instance, β-glycosidic bonds are typically more stable than α-glycosidic bonds due to their less strained configuration.

Review Questions

• How does the formation of an o-glycosidic bond influence the structure and function of carbohydrates?
  • The formation of an o-glycosidic bond influences both the structure and function of carbohydrates by linking monosaccharides together into larger oligosaccharides and polysaccharides. This linkage affects how these carbohydrates can interact with other biomolecules, influencing their role in energy storage, structural support, and cellular recognition. The specific type of glycosidic bond formed (α or β) can also determine the digestibility and functional properties of these carbohydrates in biological systems.
• Describe the difference between α and β o-glycosidic bonds and their implications for carbohydrate metabolism.
  • α o-glycosidic bonds feature the hydroxyl group on the anomeric carbon positioned below the plane of the sugar ring, while β o-glycosidic bonds have this group above the plane. This difference impacts carbohydrate metabolism because enzymes that digest carbohydrates, like amylase, can typically hydrolyze α-bonds but struggle with β-bonds found in cellulose. Consequently, humans can easily digest starch (which contains α-bonds) but cannot digest cellulose (which has β-bonds), highlighting how glycosidic bond type affects nutritional absorption.
• Evaluate how understanding o-glycosidic bonds enhances our knowledge of biochemical processes such as glycosylation.
  • Understanding o-glycosidic bonds significantly enhances our knowledge of biochemical processes like glycosylation by revealing how carbohydrates modify proteins and lipids to affect their stability, activity, and interactions. Glycosylation often involves forming o-glycosidic bonds that attach sugars to these biomolecules, influencing cell signaling, immune response, and protein folding. By studying these bonds, researchers can develop therapeutic strategies targeting glycosylation pathways to treat diseases such as cancer and diabetes, illustrating their critical role in cellular functions.

Related terms

Disaccharide: A carbohydrate composed of two monosaccharide units linked by a glycosidic bond.

Polysaccharide: A large carbohydrate molecule made up of long chains of monosaccharide units linked by glycosidic bonds.

Glycosylation:

The process of adding a carbohydrate to a protein or lipid, often involving the formation of o-glycosidic bonds.