Question

All enzymes of the TCA cycle are located in the mitochondrial matrix except one, which is located in inner mitochondrial membrane in eukaryotes and in cytosol in prokaryotes. This enzyme is

• A. Succinate dehydrogenase.
• B. Lactate dehydrogenase.
• C. Isocitrate dehydrogenase.
• D. Malate dehydrogenase.

Answer 1

The correct option is A Succinate dehydrogenase.

Krebs cycle (TCA cycle) occurs in mitochondrial matrix and produces reduced coenzymes, like $NAD{H}_2$ and $FAD{H}_2$.

The succinate dehydrogenase enzyme is bound to inner mitochondrial membrane and catalyzes the conversion of succinate to fumarate with the simultaneous reduction of FAD to $FAD{H}_2$. In prokaryotes also this enzyme is bound to plasma membrane. This enzyme is an important example of membrane bound enzyme.