Which enzyme catalyzes the conversion of malate to oxaloacetate in the Citric Acid Cycle?

The conversion of malate to oxaloacetate in the Citric Acid Cycle is catalyzed by malate dehydrogenase. This enzyme plays a crucial role in the final steps of the cycle, facilitating the reversible oxidation of malate, which is a four-carbon molecule, to oxaloacetate, another four-carbon compound. During this process, malate dehydrogenase facilitates the transfer of electrons to NAD+, converting it into NADH. This reaction is vital for maintaining the redox balance within the cycle and plays an important role in the overall energy production by linking the cycle with the electron transport chain, where NADH is used to generate ATP.

The other enzymes listed have different functions within the Citric Acid Cycle. Aconitase is involved in the isomerization of citrate to isocitrate, citrate synthase catalyzes the condensation of acetyl-CoA and oxaloacetate to form citrate, and succinate dehydrogenase catalyzes the conversion of succinate to fumarate. Each of these enzymes serves a distinct and crucial role in the flow of metabolites through the pathway, but only malate dehydrogenase is responsible for the specific reaction converting malate to oxaloacetate.