Which enzyme is primarily responsible for the conversion of Acetyl-CoA and Oxaloacetate to Citrate in the Citric Acid Cycle?

The enzyme that primarily catalyzes the conversion of Acetyl-CoA and Oxaloacetate to Citrate in the Citric Acid Cycle is citrate synthase. This reaction is critical as it represents the first step in the cycle, wherein Acetyl-CoA, a two-carbon molecule, combines with the four-carbon oxaloacetate to form the six-carbon citrate.

Citrate synthase functions through a unique mechanism that involves the formation of a citryl-CoA intermediate. This step not only facilitates the condensation reaction but also ensures that the cycle progresses efficiently. The enzyme requires a specific binding of both substrates, and it has a high specificity for Acetyl-CoA.

This reaction also plays a key regulatory role in the Citric Acid Cycle, as it represents a point of control for the overall rate of cellular respiration and energy production. Given its importance in metabolism, citrate synthase is often studied in the context of energy regulation and metabolic pathways.

Other enzymes mentioned, such as aconitase, isocitrate dehydrogenase, and succinyl-CoA synthetase, perform different functions within the cycle. Aconitase catalyzes the isomerization of citrate to isocitrate, isocitrate dehyd