β-ketoacyl-CoA is an important intermediate in the process of fatty acid β-oxidation, which is the catabolic pathway that breaks down fatty acids to generate acetyl-CoA for energy production.
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β-ketoacyl-CoA is formed when a fatty acyl-CoA undergoes the third step of β-oxidation, which involves the addition of a carbonyl group to the β-carbon.
The formation of β-ketoacyl-CoA is catalyzed by the enzyme 3-ketoacyl-CoA thiolase, also known as thiolase.
β-ketoacyl-CoA is then cleaved by thiolase to produce acetyl-CoA and a fatty acyl-CoA that is two carbons shorter, allowing the β-oxidation cycle to continue.
The acetyl-CoA generated can enter the citric acid cycle to produce ATP through oxidative phosphorylation, or it can be used as a substrate for biosynthetic pathways.
Disruptions in the β-oxidation pathway, including the formation and cleavage of β-ketoacyl-CoA, can lead to the accumulation of fatty acid intermediates and contribute to metabolic disorders such as fatty liver disease.
Review Questions
Describe the role of β-ketoacyl-CoA in the process of fatty acid β-oxidation.
β-ketoacyl-CoA is a key intermediate in the β-oxidation pathway, where fatty acids are progressively shortened to generate acetyl-CoA. It is formed when a fatty acyl-CoA undergoes the third step of β-oxidation, which involves the addition of a carbonyl group to the β-carbon. The formation of β-ketoacyl-CoA is catalyzed by the enzyme 3-ketoacyl-CoA thiolase, and it is then cleaved by the same enzyme to produce acetyl-CoA and a fatty acyl-CoA that is two carbons shorter, allowing the β-oxidation cycle to continue.
Explain how the generation of acetyl-CoA from β-ketoacyl-CoA contributes to energy production in the cell.
The acetyl-CoA produced from the cleavage of β-ketoacyl-CoA by thiolase can enter the citric acid cycle, also known as the Krebs cycle. Within the citric acid cycle, the acetyl-CoA is further oxidized, generating NADH and FADH2, which are then used in the electron transport chain to drive the production of ATP through oxidative phosphorylation. This process allows the cell to efficiently convert the energy stored in fatty acids into a usable form of energy, ATP, which can be utilized for various cellular processes.
Discuss the potential consequences of disruptions in the formation or cleavage of β-ketoacyl-CoA during fatty acid β-oxidation.
Disruptions in the β-oxidation pathway, including the formation and cleavage of β-ketoacyl-CoA, can lead to the accumulation of fatty acid intermediates and contribute to metabolic disorders. For example, a deficiency in the enzyme 3-ketoacyl-CoA thiolase, which is responsible for cleaving β-ketoacyl-CoA, can result in the buildup of this intermediate and other fatty acid metabolites. This can impair the cell's ability to efficiently generate acetyl-CoA and disrupt energy production, potentially leading to conditions like fatty liver disease or other metabolic abnormalities. Understanding the role of β-ketoacyl-CoA in the β-oxidation process is crucial for identifying and managing such metabolic disorders.
Related terms
Fatty Acid β-Oxidation: The metabolic pathway that progressively shortens fatty acid chains by removing two-carbon units in the form of acetyl-CoA, which can then enter the citric acid cycle to generate ATP.
A key metabolic intermediate that can be used to generate energy through the citric acid cycle or serve as a substrate for biosynthetic pathways.
Thiolase: An enzyme that catalyzes the final step of β-oxidation, cleaving β-ketoacyl-CoA into acetyl-CoA and a fatty acyl-CoA that is two carbons shorter.