A nontraditional role for water in the cytochrome c oxidase reaction.
The passage of electrons through cytochrome c oxidase is directly related to the activity of water. Reducing the activity in a system containing reductant, oxygen, and cytochrome oxidase blocks electron transfer between reduced cytochrome a and oxidized cytochrome a3. The extent of the block is directly related to the osmotic pressure of the system, implying that the protein shell of the oxidase acts as a semipermeable membrane that excludes osmotic perturbants but not water. It appears that approximately 10 water molecules must enter and leave the oxidase in order for internal electron transfer to occur.
Kornblatt
J A
JA
Department of Biology, Concordia University, Montreal, Quebec, Canada.
Hoa
G H
GH
D000818:Animals; D002417:Cattle; D017936:Cytochrome a Group; D003580:Cytochromes / Q000378:metabolism; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism*; D066298:In Vitro Techniques; D008956:Models, Chemical; D009206:Myocardium / Q000201:enzymology; D009997:Osmotic Pressure; D010084:Oxidation-Reduction; D012997:Solvents; D014867:Water / Q000378:metabolism*
D017936:Cytochrome a Group; D003580:Cytochromes; D012997:Solvents; D014867:Water; D003576:Electron Transport Complex IV