key term - Malate dehydrogenase

Definition

Malate dehydrogenase is an enzyme that catalyzes the reversible conversion of malate to oxaloacetate while reducing NAD+ to NADH in the citric acid cycle. This enzyme plays a crucial role in energy production and metabolic regulation by linking the cycle's intermediate steps to the electron transport chain through NADH generation.

5 Must Know Facts For Your Next Test

1. Malate dehydrogenase operates in both mitochondrial and cytosolic locations, facilitating the citric acid cycle's function in energy metabolism.
2. The enzyme is critical for the conversion of malate to oxaloacetate, which helps regenerate oxaloacetate for the continuation of the citric acid cycle.
3. The reaction catalyzed by malate dehydrogenase is dependent on the concentrations of malate and oxaloacetate, showcasing its reversible nature.
4. Malate dehydrogenase activity is influenced by factors such as pH and temperature, which can affect overall enzyme efficiency and metabolic pathways.
5. The NADH produced by malate dehydrogenase feeds into the electron transport chain, contributing to ATP production during oxidative phosphorylation.

Review Questions

• How does malate dehydrogenase contribute to the citric acid cycle and energy production?
  • Malate dehydrogenase is essential for converting malate to oxaloacetate within the citric acid cycle. This reaction not only regenerates oxaloacetate, allowing the cycle to continue but also produces NADH, which carries high-energy electrons. These electrons are later used in the electron transport chain to generate ATP, making malate dehydrogenase a crucial player in cellular energy production.
• In what ways can malate dehydrogenase activity be regulated within the cell?
  • Malate dehydrogenase activity can be regulated by substrate availability, particularly the concentrations of malate and oxaloacetate, as it operates reversibly. Additionally, environmental factors like pH and temperature can influence its enzymatic efficiency. The levels of NAD+ and NADH also play a role in regulation since they determine the direction of the reaction and thus influence overall metabolic flux.
• Evaluate the significance of malate dehydrogenase in relation to metabolic disorders and potential therapeutic targets.
  • Malate dehydrogenase plays a significant role in maintaining metabolic balance, so its dysfunction could contribute to metabolic disorders such as diabetes or obesity. Understanding its regulation and function can help identify therapeutic targets for managing these conditions. By influencing malate dehydrogenase activity, it may be possible to enhance energy production or correct metabolic imbalances, presenting opportunities for innovative treatments in metabolic disease management.

Related terms

Citric Acid Cycle: A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

NADH:

Nicotinamide adenine dinucleotide (NAD+) in its reduced form, which serves as a key electron carrier in cellular respiration, playing a vital role in energy metabolism.

Oxaloacetate: A four-carbon molecule that combines with acetyl-CoA to form citrate at the start of the citric acid cycle, and is also regenerated at the end of the cycle.