Which enzyme connects the Citric Acid Cycle to the electron transport chain?

The enzyme that connects the Citric Acid Cycle to the electron transport chain is Succinate dehydrogenase. This enzyme is unique because it is the only enzyme in the citric acid cycle that is located in the inner mitochondrial membrane. It plays a critical role in both the citric acid cycle and the process of oxidative phosphorylation.

During its function within the citric acid cycle, succinate dehydrogenase catalyzes the conversion of succinate to fumarate, simultaneously reducing FAD (flavin adenine dinucleotide) to FADH2. This FADH2 then feeds electrons directly into the electron transport chain, contributing to the generation of ATP through oxidative phosphorylation. This direct link is essential for cellular respiration, as it allows the energy stored in the citric acid cycle to be used in the production of ATP, the energy currency of the cell.

The other enzymes listed are integral to various steps within the citric acid cycle, but they do not serve as a direct connection to the electron transport chain. Understanding the role of succinate dehydrogenase helps clarify its functional importance in bridging these two crucial metabolic pathways.