Function 
Cytochrome c oxidase (CcO) is a transmembrane protein complex found in bacteria and mitochondria.   CcO is the last enzyme in the electron transport chain. [1]
- Ba3-type cytochrome c oxidase substrate is cytochrome c552 [2].
See also Hemeproteins.
  Disease 
CcO deficiency is a genetic condition which affects muscle weakness, muscle tone upto severe brain dysfunction in severe cases.
  Structural highlights 
Mammalian CcO is composed of , , and cytochrome a and a3.  The fully oxidized form of  molecule. . [3]  Bacterial CcO is composed of 2 subunits.
  3D Structures of Cytochrome c oxidase 
Cytochrome c oxidase  3D structures