- Functional groups
- Non-covalent interactions
- Digestion of biomolecules
- Glycolysis and fates of pyruvate
- Krebs cycle
- Cellular respiration
- Glycogen metabolism and gluconeogenesis
- Pentose phosphate pathway
- Fatty acids metabolism
- Cholesterol metabolism
- Aminoacids metabolism
Monday, June 2, 2014
Cellular respiration - Complex III
From the structural point of view, the complex III presents a dimeric structure composed of two monomers with at least 11 subunits. Of these, three of each of the monomers have a direct role in the transfer of electrons along the complex. Of all the subunits, we should highlight the presence of cytochrome b and Rieske protein, which is a protein with a Fe-S center, more specifically 2Fe-2S.
As it happens with complex I (and IV , as I will develop in a future post), the flow of the electrons through complex III liberates energy, and that energy is used to actively transport H+ from the matrix to the intermembrane space, creating an electrochemical gradient, which subsequently will be involved in the synthesis of ATP. In this case, for each 2 electrons that are transported along complex III, 4H+ are transferred to the intermembrane space.
The complex III is inhibited, for example, by antimycin A. When it is inhibited, it can lead to the leakage of electrons that can reduce molecular oxygen, originating superoxide anion. Therefore, besides the potentially severe consequences associated with the inhibition of the respiratory chain, oxidative stress may also occur.