The Oxidative phosphorylation reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Oxidative phosphorylation

Oxidative phosphorylation is a biochemical process in cellss. It is the final metabolic pathway of cellular respiration, after glycolysis and the citric acid cycle. 26 of the total 30 ATP (energy carrier) molecules generated from a single glucose molecule during cellular respiration come from oxidative phosphorylation.

The process takes place at a biological membrane. In prokaryotes this is the plasma membrane, and in eukaryotes it is the inner of the two mitochondrial membranes. NADH and FADH2, electron carrier molecules that were "loaded" during the citric acid cycle, are used in an intricate mechanism (involving NADH-Q reductase, cytochrome c oxidase, and cytochrome reductase) to pump H⁺ across the membrane against a proton gradient.

A large protein complex called ATP synthase is embedded in that membrane and enables protons to pass through in both directions; it generates ATP when the proton moves with (down) the gradient, and it costs ATP to pump a proton against (up) the gradient. Because protons have already been pumped into the intermembrane space against the gradient, they now can flow back into the mitochondrial matrix via the ATP synthase, generating ATP in the process. The reaction is:

ADP^3- + H⁺ + P_i ↔ ATP^4- + H₂O

Reactive oxygen species

Several highly reactive, transient oxygen derivatives can be formed during this process:

1. Hydrogen peroxide
2. Superoxide anion
3. Hydroxyl radicle

This is the "Oxidative phosphorylation" reference article from the English Wikipedia. All text is available under the terms of the GNU Free Documentation License. See also our Disclaimer.