succinateubiquinone

Succinateubiquinone, also known as Complex II or succinate dehydrogenase, is a crucial enzyme involved in both the citric acid cycle and the electron transport chain within cellular respiration. It is embedded in the inner mitochondrial membrane of eukaryotes and the plasma membrane of bacteria. Its primary function is to catalyze the oxidation of succinate to fumarate in the citric acid cycle, simultaneously reducing ubiquinone (Coenzyme Q) to ubiquinol. This process transfers electrons from succinate to the ubiquinone pool, which is essential for ATP production. Unlike other complexes in the electron transport chain, Complex II does not pump protons across the mitochondrial membrane, meaning it does not directly contribute to the proton gradient. However, it plays a vital role in channeling electrons from the citric acid cycle into the main respiratory chain. The enzyme is a heterotetrameric complex composed of four subunits, with a flavin adenine dinucleotide (FAD) prosthetic group and three iron-sulfur clusters facilitating electron transfer.