Information on EC 1.10.2.2 - quinol-cytochrome-c reductase

The enzyme, often referred to as the cytochrome bc₁ complex or complex III, is the third complex in the electron transport chain. It is present in the mitochondria of all aerobic eukaryotes and in the inner membranes of most bacteria. The mammalian enzyme contains cytochromes b-562, b-566 and c₁, and a 2-iron ferredoxin. Depending on the organism and physiological conditions, the enzyme extrudes either two or four protons from the cytoplasmic to the non-cytoplasmic compartment (cf. EC 1.6.99.3, NADH dehydrogenase).