RESPIRATORY CHAIN
Respiratory (electron transport) chain, the chain for electron transport in mitochondria, is a specific protein ensemble built into the inner membrane of mitochondria. Moving along this chain, an electron gradually loses its energy and finishes its way joining molecular oxygen. The energy of electrons is used for transport of protons through the inner membrane from the matrix into the intermembranous space. Nearly 20 electron transporters forming electron transport chain are known. They are grouped into three large ensembles:
A connecting link between the first and the second complexes is the coenzyme Q (ubiquinone); between the second and the third complexes it is the cytochrome c. Cytochromes contain a prosthetic group, haem. In the region of the ensembles the transport of protons from the matrix into the intermembranous space takes place. Only NAD, flavins and ubiquinone are two-electron among them, whereas the rest of the components of the electron transport chain are one-electron.
