Cytochrome C

Cytochrome C oxidase is a protein that is found in the inner membrane of the mitochondria as an integral transmembrane protein. It is the final unit in the electron transport chain. Its structure contains 14 subunits and two hemes. The second photo below shows the structure.

The Cytochrome C oxidase functions in many ways. First, it transfers 4 protons at a time into the inner membrane space to establish the proton gradient. It then takes the electrons and transfers them to the oxygen molecule to start the formation molecular oxygen. It also binds the protons that travel through the ATP synthase to that oxygen molecule to make 2 complete molecular oxygens.

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References:

• http://www.sciencemag.org/content/280/5370/1712/F1.medium.gif
• http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/Cmplx4.PNG/300px-Cmplx4.PNG

ATP Synthase

We owe our life and energy to this little molecular motor, the ATP Synthase. This cute motor lies across the inner membrane of the mitochondria. It extends into the intermembrane space and the mitochondrial matrix. Its function is to use a chemical gradient to fuel the creation of ATP.

The F1 unit of the ATP synthase is composed of 5 different subunits: 3 alpha, 3 beta,1 gamma, 1 delta, and 1 epsilon. The subunit that binds the substrate is the beta.

The electron transport chain functions in transferring protons from the mitochondrial matrix into the intermembrane space. The proton then travel through the ATP synthase, where when two travel down they will connect with an oxygen to form water. When they travel through the ATP synthase, it allows it the energy to converty ADP + Pi to ATP.



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References:
Information: http://www.life.illinois.edu/crofts/bioph354/lect10.html
Picture: http://www.uic.edu/classes/bios/bios100/lectures/respiration.htm