Cytochrome C Oxidase: The Amazing Everyday Protein

Cytochrom C Oxidase from PDB #1OCO was generated with PyMol  

Cytochrome C oxidase is also known as Complex IV in the electron transport chain.  It transfers electrons and protons from reduced cytochrome C and conserves the free energy  by creating a proton gradient which is then used to drive the synthesis of ATP.  This is a metalloprotein that is in a super family of heme-copper containing proteins.  This protein is the final step in mitochondrial respiratory which is the principle energy-generating system for cells!  There are five metals located in the active site of cytochrome C oxidase which does redox chemistry with cytochrome C to transport protons to the inner membrane and to O₂.  This protein can take O₂ and create two waters by adding four protons yet makes sure four more protons gets to the inner membrane so that ATP can be generated.  Without Cytochrome C oxidase the whole energy-transducing process is shut down which leads to no energy being produced. 

Cytochrome C Oxidase or Complex IV

 There are four heme groups within cytochrome c oxidase.  Around these heme groups there are copper ions which help drive the formation of water and the proton gradient.  These coppers take the electrons from cytochrome c to then transfer to O_2. This process isn't done anywhere else and can only be done within cytochrome c oxidase!

Active Site of Cytochrome C Oxidase, from PDB #2GSM generated by PyMol

Subunit I and II with active site, from PDB #2GSM generated by PyMol

Cytochrome c oxidase doesn't silently kill you or attack your body.  In fact, it does the complete opposite.  This protein is able to take plain old electrons and protons and create the major energy source for your body as well as a waste product that most people wouldn't even consider waste.  Cytochrome c oxidase isn't in a super family for no reason, it has enough metal in it to put hemoglobin to shame as well as transfer protons across a membrane without needing any energy input at all.  Without this protein doing it's job, you wouldn't be able to survive. Other proteins have to get into your body to before they can do anything yet cytochrome c oxidase is already there.  So, when making your choice for protein of the year remember, cytochrome c oxidase lets you, be you.  

Citations:
Taanman, JanWillem. "Human Cytochrome c Oxidase: Structure, Function, and Deficiency." Journal of Bioenergetics and Biomembranes 29.2 (1997): 151-63. Print.
http://link.springer.com/article/10.1023%2FA%3A1022638013825?LI=true

Muramoto, Kazumasa, and Kunio Hirata. "A histidine residue acting as a controlling site for dioxygen reduction and proton pumping by cytochrome c oxidase." Biophysics 104.19 (2007): 7881-86. Web. 13 Apr. 2013.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1876541/

Tsukihara, Tomitake, and Kunitoshi Shimokata. "The low-spin heme of cytochrome c oxidase as the driving element of the proton-pumping process." Chemistry 100.26 (2003): 15304-09. Web. 13 Apr. 2013.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC307562/
Image Citation:
Yoshida, Masasuke, Eiro Muneyuki, and Toru Misabori. "ATP synthase — a marvellous rotary engine of the cell." Nature Reviews Molecular Cell Biology 2.9 (2001): 669-77. Print.