szukcinátdehidrogenáz

Succinate dehydrogenase, also known as Complex II of the electron transport chain or succinate-coenzyme Q reductase, is an enzyme complex that plays a dual role in cellular respiration. It is embedded in the inner mitochondrial membrane in eukaryotes and the plasma membrane in prokaryotes. Its primary function is to catalyze the oxidation of succinate to fumarate in the citric acid cycle, a crucial step in glucose metabolism. This reaction involves the transfer of electrons from succinate to flavin adenine dinucleotide (FAD), which is covalently bound to the enzyme. The reduced FADH2 then passes these electrons to ubiquinone (coenzyme Q), a mobile electron carrier.

In addition to its role in the citric acid cycle, succinate dehydrogenase is also a component of the electron transport chain. It donates electrons to the electron transport chain, contributing to the generation of a proton gradient across the inner mitochondrial membrane. This gradient is then used by ATP synthase to produce ATP, the main energy currency of the cell. The enzyme complex is composed of four subunits: two hydrophobic subunits that anchor it to the membrane and contain the ubiquinone binding site, and two hydrophilic subunits that contain the succinate binding site and the FAD cofactor. Mutations in the genes encoding succinate dehydrogenase subunits can lead to various diseases, including certain types of cancer and neurodegenerative disorders, highlighting its critical importance in cellular function.