Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.

Succinate is the substrate, and fumarate is the product.

Explanation:

Succinate dehydrogenase is known as an enzyme complex occurs in the inner mitochondrial membrane of the eukaryotes, and many bacterial cells. This is the only enzyme that helps to contribute to both the citric acid cycle and ETC (electron transport chain). In the 6th step of the cycle, SQR utilizes the oxidation of succinate to fumarate and the reduction of ubiquinone to ubiquinol occurs.

This occurs in the inner mitochondrial membrane by pairing the 2 reactions together. Succinate and fumarate only differ in their geometrical structure around their double bond, and the other contains a trans double bond.