Succinaattidehydrogenaasi

Succinaattidehydrogenaasi, also known as Complex II or succinate-ubiquinone oxidoreductase, is an enzyme that plays a crucial role in both cellular respiration and the citric acid cycle. It is located in the inner mitochondrial membrane of eukaryotic cells and in the plasma membrane of prokaryotes. The enzyme catalyzes the oxidation of succinate to fumarate, a key reaction in the citric acid cycle, while simultaneously reducing ubiquinone (coenzyme Q) to ubiquinol. This process transfers electrons from succinate to the electron transport chain, contributing to the generation of ATP. Succinate dehydrogenase is unique among the enzymes of the citric acid cycle because it is the only enzyme that is embedded within the inner mitochondrial membrane, linking it directly to the electron transport chain. It is composed of four subunits, including a flavoprotein subunit that contains flavin adenine dinucleotide (FAD) and three iron-sulfur protein subunits. Inhibition of succinate dehydrogenase can have significant metabolic consequences, and the enzyme is a target for certain toxins and drugs.