Which mitochondrial enzyme is responsible for the conversion of succinate to fumarate?

• A. A. Malate dehydrogenase.
• B. B. Succinate dehydrogenase.
• C. C. Citrate synthase.
• D. D. Fumarase.

Answer: (B)

Succinate dehydrogenase is the mitochondrial enzyme specifically responsible for catalyzing the conversion of succinate to fumarate in the citric acid cycle (Krebs cycle). This enzyme plays a critical role as it is not only a part of the citric acid cycle but also functions in the electron transport chain, linking the two processes. During the reaction, succinate is oxidized to fumarate, and in this process, FAD (flavin adenine dinucleotide) is reduced to FADH2, which then contributes to the generation of ATP through oxidative phosphorylation.

The reaction that occurs with succinate dehydrogenase highlights its dual function and essentiality in energy metabolism within the mitochondria. Understanding this enzyme's role is fundamental in biochemistry, particularly concerning how energy is produced and the intricate pathways involved in cellular respiration.