Why is it important for succinate dehydrogenase to quickly oxidize its FADH2 prosthetic group?

Succinate dehydrogenase plays a pivotal role in the citric acid cycle by catalyzing the oxidation of succinate to fumarate, while concurrently reducing its prosthetic group, FAD, to FADH2. The rapid oxidation of FADH2 is crucial because succinate dehydrogenase needs to regenerate its active form, which is FAD, to continue catalyzing reactions in the cycle. If FADH2 is not quickly oxidized back to FAD, the enzyme becomes inactivated and cannot participate further in the citric acid cycle.

This rapid oxidation ensures that the enzyme can efficiently handle multiple substrate molecules, maintaining the flow of the cycle. By converting FADH2 back to FAD, the enzyme is prepared to accept another succinate molecule for further processing, which is essential for overall metabolic efficiency. Hence, the turnover of the enzyme relies on this prompt re-oxidation process, effectively allowing the enzyme to engage in subsequent catalytic cycles without hindrance.