Ubiquinone dehydrogenase

Ubiquinone dehydrogenase is a large enzyme complex within the inner mitochondrial membrane. It is an intermediate in the electron transfer chain.

It consists of:

• cytochrome b:
  • has haem prosthetic group
  • accepts electrons from ubiquinone to produce an Fe 2+ redox state
  • transfers electron to ubiquinol to recycle Fe 3+ state
• ubiquinol: transfers electron to ferrous carrier by oxidation
• ferrous carrier: transfers electron to cytochrome c1 by oxidation
• cytochrome c1:
  • contains haem prosthetic group
  • reduced by transfer of electrons from ferrous carrier
  • reoxidized by transfer of electrons to cytochrome c

The passage of 1 electron through the ubiquinone dehydrogenase complex acts to pump 1 proton into the mitochondrial intermembranous space. Ultimately, this produces 1 molecule of ATP through oxidative phosphorylation.