L-β-hydroxyacyl-CoA dehydrogenase

Definition

L-β-hydroxyacyl-CoA dehydrogenase is an enzyme that catalyzes a key step in the β-oxidation pathway, which is the process of breaking down fatty acids to generate energy for the body. This enzyme is responsible for the oxidation of L-β-hydroxyacyl-CoA intermediates, an essential part of the catabolism of triacylglycerols.

5 Must Know Facts For Your Next Test

1. L-β-hydroxyacyl-CoA dehydrogenase catalyzes the third step of the β-oxidation pathway, where it oxidizes L-β-hydroxyacyl-CoA to β-ketoacyl-CoA.
2. This enzyme requires the cofactor NAD+ and produces NADH, which can then be used in the electron transport chain to generate ATP.
3. Deficiencies in L-β-hydroxyacyl-CoA dehydrogenase can lead to metabolic disorders, such as medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, which can result in hypoglycemia and other serious health issues.
4. The activity of L-β-hydroxyacyl-CoA dehydrogenase is regulated by the availability of its substrate, L-β-hydroxyacyl-CoA, which is produced in the previous step of the β-oxidation pathway.
5. Proper functioning of L-β-hydroxyacyl-CoA dehydrogenase is crucial for the efficient breakdown of fatty acids and the generation of energy in the body.

Review Questions

• Describe the role of L-β-hydroxyacyl-CoA dehydrogenase in the β-oxidation pathway.
  • L-β-hydroxyacyl-CoA dehydrogenase catalyzes the third step of the β-oxidation pathway, where it oxidizes L-β-hydroxyacyl-CoA to β-ketoacyl-CoA. This reaction is essential for the continued breakdown of fatty acids to generate acetyl-CoA, which can then enter the citric acid cycle to produce ATP. The enzyme requires the cofactor NAD+ and produces NADH, which can be used in the electron transport chain to generate additional ATP.
• Explain how deficiencies in L-β-hydroxyacyl-CoA dehydrogenase can lead to metabolic disorders.
  • Deficiencies in L-β-hydroxyacyl-CoA dehydrogenase can result in the accumulation of L-β-hydroxyacyl-CoA and other intermediates, which can disrupt normal metabolic processes. This can lead to conditions like medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, where the body is unable to properly break down fatty acids. Symptoms of MCAD deficiency can include hypoglycemia, lethargy, and potentially life-threatening metabolic crises, highlighting the importance of this enzyme in maintaining overall metabolic health.
• Analyze the regulation of L-β-hydroxyacyl-CoA dehydrogenase activity and its significance in the context of the β-oxidation pathway.
  • The activity of L-β-hydroxyacyl-CoA dehydrogenase is primarily regulated by the availability of its substrate, L-β-hydroxyacyl-CoA, which is produced in the previous step of the β-oxidation pathway. When L-β-hydroxyacyl-CoA is abundant, the enzyme is more active, allowing for the continued breakdown of fatty acids and the generation of acetyl-CoA for the citric acid cycle. Conversely, if L-β-hydroxyacyl-CoA levels are low, the enzyme's activity is reduced, potentially slowing down the overall β-oxidation process. This regulation ensures that the breakdown of fatty acids is closely matched to the body's energy needs, promoting efficient energy production and maintaining metabolic homeostasis.

Related terms

β-Oxidation: The catabolic process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-CoA, which can then enter the citric acid cycle to produce ATP.

Acetyl-CoA: A key molecule in cellular metabolism that is produced from the breakdown of carbohydrates, fats, and proteins, and can be further oxidized in the citric acid cycle to generate ATP.

Citric Acid Cycle: Also known as the Krebs cycle, this is a series of chemical reactions that occur in the mitochondria and is a key part of cellular respiration, where acetyl-CoA is oxidized to carbon dioxide and water, generating ATP in the process.