Thiolase

Thiolase, also known as acetoacetyl-CoA acetyltransferase, is an enzyme that plays a fundamental role in metabolic processes. It is involved in the ketogenesis pathway, fatty acid metabolism, and the mevalonate pathway, which is responsible for the synthesis of sterols and other isoprenoids.

Function

Thiolase catalyzes the last step of the beta-oxidation cycle, a metabolic pathway involved in the breakdown of fatty acids. This reaction involves the cleavage of acetoacetyl CoA into two molecules of acetyl CoA. Thiolase also plays a role in the synthesis of ketone bodies, which are produced in the liver and used as an energy source by the brain during periods of fasting.

Structure

Thiolase is a dimeric enzyme, meaning it is composed of two identical subunits. Each subunit contains a catalytic triad consisting of three amino acids: cysteine, histidine, and aspartate. The cysteine residue is responsible for the enzyme's thiolase activity.

Clinical significance

Mutations in the gene encoding thiolase can lead to a rare metabolic disorder known as beta-ketothiolase deficiency. This condition is characterized by an inability to effectively break down certain amino acids and lipids, leading to a buildup of harmful substances in the body.

See also

• Acetoacetyl CoA
• Beta-oxidation
• Ketogenesis
• Fatty acid metabolism

References

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  Mevalonate pathway
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  Thiolase reaction catalysis
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  Thiolase mechanism