Beta-Hydroxybutyryl-CoA

Beta-Hydroxybutyryl-CoA is an important intermediate in the metabolism of fatty acids. It is a Coenzyme A derivative of beta-hydroxybutyrate, a ketone body that serves as an alternative energy source during periods of fasting or starvation.

Structure of Beta-Hydroxybutyryl-CoA

Structure and Function

Beta-Hydroxybutyryl-CoA is a thioester of Coenzyme A and beta-hydroxybutyrate. The molecule consists of a beta-hydroxybutyrate moiety linked to a Coenzyme A moiety via a high-energy thioester bond. This bond is hydrolyzed in the final step of beta-oxidation, releasing energy that is used to produce ATP.

Role in Metabolism

In the process of beta-oxidation, fatty acids are broken down in the mitochondria to produce acetyl-CoA, which enters the citric acid cycle to generate ATP. However, during periods of fasting or starvation, the body's supply of glucose is depleted, and alternative energy sources are needed. In these conditions, the liver converts acetyl-CoA into ketone bodies, including beta-hydroxybutyrate.

Beta-Hydroxybutyrate is then transported to other tissues, such as the brain, where it is converted back into acetyl-CoA via beta-hydroxybutyryl-CoA. This allows the brain to continue functioning even when glucose is scarce.

Clinical Significance

Elevated levels of beta-hydroxybutyrate and other ketone bodies can lead to a condition known as ketoacidosis, which is often seen in uncontrolled diabetes. This can be detected in the blood or urine and is a sign that the body is relying heavily on fat metabolism for energy.

See Also

• Beta-oxidation
• Ketone bodies
• Coenzyme A
• Ketoacidosis