Electron transport system
- The metabolic pathway through which the electron passes from one carrier to another, is called the electron transport system (ETS).
- Electron transport system takes place in inner mitochondrial membrane.
- Electron transport chain comprises of the following:
- Complex I: NADH dehydrogenase
- Complex II: succinate dehydrogenase
- Complex III: cytochromes bc1
- Complex IV: cytochromes a-a3
- Complex V: ATP synthase
- NADH2 is oxidized by NADH dehydrogenase and electrons are then transferred to ubiquinone located in the inner mitochondrial membrane.
- FADH2 is oxidized by succinate dehydrogenase and transferred electrons to ubiquinone.
- The reduced ubiquinone is then oxidized with transfer of electrons via cytochromes bc1 complex to cytochrome c.
- Cytochrome c is a small protein attached to the outer surface of the inner membrane and transfer electrons from complex III to complex IV.
- When electrons transferred from one carrier to another via complex I to complex IV, they are coupled to ATP synthesis of ATP from ADP and Pi.
- Oxygen plays a vital role in removing electrons and hydrogen ion and finally helps in the production of H2
Fig. Electron transport chain