Succinate dehydrogenase provides a link between the citric acid cycleand the membrane-bound electron transport system. The enzyme catalyses the interconversion of fumarate and succinate, and is closely related to fumarate reductase. Related Theory The major significance of the citric acid cycle is to act as the final common pathway for the oxidation of carbohydrates, lipids and proteins, since glucose, fatty acids and many amino acids are all metabolised to acetyl CoA.