β-hydroxybutyrate dehydrogenase is an enzyme that catalyzes the reversible oxidation of β-hydroxybutyrate to acetoacetate, a key step in the metabolism of ketone bodies. It plays a crucial role in the biological reduction processes outlined in the chapter on 19.12 Biological Reductions.
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β-hydroxybutyrate dehydrogenase is a mitochondrial enzyme that plays a key role in the metabolism of ketone bodies.
The enzyme catalyzes the reversible conversion of β-hydroxybutyrate to acetoacetate, which is an important step in the utilization of ketone bodies for energy production.
During periods of fasting or low carbohydrate intake, the liver increases the production of ketone bodies, including β-hydroxybutyrate, as an alternative energy source for the body.
The activity of β-hydroxybutyrate dehydrogenase is regulated by the availability of its substrates and the energy state of the cell, helping to maintain the balance between ketone body production and utilization.
Impairment of β-hydroxybutyrate dehydrogenase activity can lead to the accumulation of ketone bodies, a condition known as ketoacidosis, which is a serious complication seen in uncontrolled diabetes.
Review Questions
Describe the role of β-hydroxybutyrate dehydrogenase in the metabolism of ketone bodies.
β-hydroxybutyrate dehydrogenase catalyzes the reversible conversion of β-hydroxybutyrate to acetoacetate, a key step in the utilization of ketone bodies as an alternative energy source. During periods of fasting or low carbohydrate intake, the liver increases the production of ketone bodies, including β-hydroxybutyrate, which can then be converted to acetoacetate by β-hydroxybutyrate dehydrogenase. This allows the body to use ketone bodies as an energy source when glucose is scarce, helping to maintain metabolic homeostasis.
Explain how the activity of β-hydroxybutyrate dehydrogenase is regulated and the consequences of its impairment.
The activity of β-hydroxybutyrate dehydrogenase is regulated by the availability of its substrates, β-hydroxybutyrate and acetoacetate, as well as the energy state of the cell. When the cell's energy demands are high and glucose is scarce, the enzyme's activity increases to facilitate the conversion of β-hydroxybutyrate to acetoacetate, allowing the body to utilize ketone bodies as an energy source. Conversely, when energy is abundant, the enzyme's activity decreases to maintain the balance between ketone body production and utilization. Impairment of β-hydroxybutyrate dehydrogenase activity can lead to the accumulation of ketone bodies, a condition known as ketoacidosis, which is a serious complication seen in uncontrolled diabetes and can be life-threatening if left untreated.
Analyze the significance of β-hydroxybutyrate dehydrogenase in the context of 19.12 Biological Reductions and its broader implications for metabolic processes.
In the context of 19.12 Biological Reductions, β-hydroxybutyrate dehydrogenase plays a crucial role in the reversible oxidation-reduction reactions involving ketone bodies. The enzyme's ability to catalyze the interconversion of β-hydroxybutyrate and acetoacetate is essential for the body's ability to utilize ketone bodies as an alternative energy source when glucose is scarce, such as during fasting or prolonged exercise. This flexibility in energy metabolism, facilitated by β-hydroxybutyrate dehydrogenase, allows the body to maintain homeostasis and adapt to changing energy demands. Furthermore, the regulation of this enzyme's activity is closely tied to the overall energy state of the cell, highlighting its broader significance in the coordination of metabolic processes. Impairment of β-hydroxybutyrate dehydrogenase can lead to serious metabolic imbalances, underscoring the importance of this enzyme in maintaining healthy metabolic function.
Ketone bodies are water-soluble molecules produced by the liver as a byproduct of fat metabolism. They can be used as an alternative energy source when glucose is scarce.
Acetoacetate: Acetoacetate is a ketone body produced by the liver during the breakdown of fatty acids. It can be further converted to other ketone bodies or used as an energy source.
Oxidation-Reduction Reactions: Oxidation-reduction (redox) reactions involve the transfer of electrons between molecules, resulting in a change in the oxidation state of the atoms involved.