β-hydroxybutyrate dehydrogenase

Definition

β-hydroxybutyrate dehydrogenase is an enzyme that plays a crucial role in the metabolism of ketone bodies, specifically in the conversion of acetoacetate to β-hydroxybutyrate. This enzyme is significant for energy production during periods of fasting or low carbohydrate intake, linking fatty acid degradation to energy generation in various tissues, especially the brain and heart.

5 Must Know Facts For Your Next Test

1. β-hydroxybutyrate dehydrogenase catalyzes the reversible conversion between acetoacetate and β-hydroxybutyrate, playing a key role in regulating ketone body levels in the blood.
2. This enzyme functions optimally in conditions such as prolonged fasting, starvation, or low-carbohydrate diets, where ketone bodies become a major source of energy.
3. The enzyme requires NAD+ as a cofactor for its activity, facilitating the reduction of acetoacetate to β-hydroxybutyrate while oxidizing NADH to NAD+.
4. β-hydroxybutyrate is often measured as a biomarker for ketosis and is important in clinical settings for managing conditions like diabetes and metabolic disorders.
5. Inhibition or dysfunction of β-hydroxybutyrate dehydrogenase can lead to an accumulation of acetoacetate and a decrease in β-hydroxybutyrate, potentially disrupting energy metabolism.

Review Questions

• How does β-hydroxybutyrate dehydrogenase contribute to the regulation of ketone body metabolism?
  • β-hydroxybutyrate dehydrogenase regulates ketone body metabolism by facilitating the interconversion between acetoacetate and β-hydroxybutyrate. This enzyme's activity determines the balance of these two ketone bodies in the bloodstream, especially during states like fasting or low carbohydrate intake. By converting acetoacetate into β-hydroxybutyrate, it helps maintain adequate energy levels when glucose is scarce.
• Discuss the role of β-hydroxybutyrate dehydrogenase in energy production during fasting states.
  • During fasting states, β-hydroxybutyrate dehydrogenase becomes increasingly important as it aids in the production of β-hydroxybutyrate from acetoacetate. This conversion allows the brain and heart to utilize ketone bodies as an alternative energy source when glucose levels are low. The enzyme's activity helps ensure that these vital organs receive sufficient energy, highlighting its critical role in metabolic adaptation during periods of nutrient deprivation.
• Evaluate the implications of altered β-hydroxybutyrate dehydrogenase activity on metabolic health and disease.
  • Altered activity of β-hydroxybutyrate dehydrogenase can have significant implications for metabolic health. For instance, reduced enzyme function may lead to inadequate ketone body production, impacting energy availability during fasting or low-carbohydrate diets. This could exacerbate conditions like diabetes or metabolic syndrome by preventing proper metabolic flexibility. Conversely, excessive activity may contribute to ketoacidosis in diabetic patients, where high levels of ketones result in acidosis, showcasing the importance of maintaining balanced enzymatic function for overall metabolic health.

Related terms

Ketogenesis: The metabolic process by which fatty acids are converted into ketone bodies, primarily in the liver, during periods of low carbohydrate availability.

Acetoacetate: A type of ketone body that serves as an intermediate in the metabolism of fatty acids and is converted to β-hydroxybutyrate by the action of β-hydroxybutyrate dehydrogenase.

Fatty Acid Oxidation: The metabolic pathway through which fatty acids are broken down to generate acetyl-CoA, which can be used for energy production or converted into ketone bodies.