key term - Enoyl-CoA hydratase

Definition

Enoyl-CoA hydratase is an enzyme that catalyzes a key step in the beta-oxidation of fatty acids, where it adds water to an enoyl-CoA intermediate to form a 3-hydroxyacyl-CoA product. This enzyme plays a crucial role in the catabolic breakdown of triacylglycerols and the generation of energy from fatty acid sources.

5 Must Know Facts For Your Next Test

1. Enoyl-CoA hydratase catalyzes the addition of water to the double bond of an enoyl-CoA intermediate, converting it to a 3-hydroxyacyl-CoA product during the beta-oxidation of fatty acids.
2. This enzyme is essential for the complete breakdown of fatty acids, as it allows the process to continue by generating a substrate for the next step in the beta-oxidation pathway.
3. Enoyl-CoA hydratase is found in the mitochondria, where beta-oxidation of fatty acids primarily occurs.
4. Deficiencies or mutations in the gene encoding enoyl-CoA hydratase can lead to metabolic disorders, such as 3-hydroxyacyl-CoA dehydrogenase deficiency, which can result in severe health issues.
5. The activity of enoyl-CoA hydratase is regulated by various factors, including the availability of substrates, the redox state of the cell, and the presence of specific cofactors or allosteric modulators.

Review Questions

• Explain the role of enoyl-CoA hydratase in the context of biological elimination reactions.
  • Enoyl-CoA hydratase plays a key role in the beta-oxidation of fatty acids, which is a catabolic process involving the stepwise removal of two-carbon units from the fatty acid chain. Specifically, enoyl-CoA hydratase catalyzes the addition of water to an enoyl-CoA intermediate, converting it to a 3-hydroxyacyl-CoA product. This step is crucial for the continuation of the beta-oxidation pathway, as it generates a substrate for the next enzymatic reaction. By facilitating the elimination of water from the fatty acid chain, enoyl-CoA hydratase enables the complete breakdown of fatty acids to acetyl-CoA, which can then enter the citric acid cycle to produce energy in the form of ATP.
• Describe how the activity of enoyl-CoA hydratase is regulated in the context of the catabolism of triacylglycerols and beta-oxidation.
  • The activity of enoyl-CoA hydratase is tightly regulated to ensure the efficient and controlled catabolism of triacylglycerols through the beta-oxidation pathway. The availability of substrates, such as enoyl-CoA intermediates, is a key factor that influences the enzyme's activity. Additionally, the redox state of the cell, as reflected by the levels of cofactors like NAD+ and NADH, can modulate enoyl-CoA hydratase's function. For example, a high NADH/NAD+ ratio can inhibit the enzyme, slowing down beta-oxidation and conserving energy resources. Allosteric regulators, such as certain metabolites or hormones, can also bind to enoyl-CoA hydratase and alter its catalytic efficiency, thereby adjusting the rate of fatty acid breakdown to meet the cell's energy demands.
• Analyze the potential consequences of a deficiency or mutation in the gene encoding enoyl-CoA hydratase, and explain how this could impact the catabolism of triacylglycerols and overall energy metabolism.
  • A deficiency or mutation in the gene encoding enoyl-CoA hydratase can have severe consequences for the catabolism of triacylglycerols and overall energy metabolism. Without a functional enoyl-CoA hydratase enzyme, the beta-oxidation pathway would be disrupted, leading to the accumulation of enoyl-CoA intermediates and the inability to fully break down fatty acids. This would result in a decreased production of acetyl-CoA, which is the primary substrate for the citric acid cycle and the generation of ATP. The impaired energy production from fatty acid sources would force the body to rely more heavily on alternative energy sources, such as carbohydrates or protein, which may not be sufficient to meet the body's energy demands. Furthermore, the accumulation of partially oxidized fatty acid intermediates could lead to the development of metabolic disorders, such as 3-hydroxyacyl-CoA dehydrogenase deficiency, which can cause a range of health issues, including developmental delays, neurological problems, and life-threatening metabolic crises.

Related terms

Beta-oxidation: The process by which fatty acids are broken down to generate acetyl-CoA, which can then enter the citric acid cycle to produce ATP.

Acyl-CoA: A thioester formed between a fatty acid and coenzyme A, which is the activated form of a fatty acid that can undergo various metabolic transformations.

Citric acid cycle:

Also known as the Krebs cycle, this is a series of chemical reactions that occur in the mitochondria to oxidize acetyl-CoA and produce NADH and FADH2, which are used to generate ATP.