FAD

In biochemistry, flavin adenine dinucleotide (FAD) is a redox coenzyme involved in several important reactions in metabolism. FAD can exist in two different redox states and its biochemical role usually involves changing between these two states. FAD can be reduced to the FADH2, whereby it accepts two hydrogen atoms:


 * [[Image:FAD FADH2 equlibrium.png|422px]]

FADH2 is an energy-carrying molecule, and the reduced coenzyme can be used as a substrate for oxidative phosphorylation in the mitochondria. FADH2 is reoxidized to FAD, which makes it possible to produce two moles of the universal energy carrier ATP. The primary sources of reduced FAD in eukaryotic metabolism are the citric acid cycle and the beta oxidation reaction pathways. In the citric acid cycle, FAD is a prosthetic group in the enzyme succinate dehydrogenase that oxidizes succinate to fumarate, whereas in beta oxidation it serves as a coenzyme in the reaction of acyl CoA dehydrogenase.

FAD is derived from riboflavin, or vitamin B2. Many oxidoreductases, called flavoenzymes or flavoproteins, require FAD as a prosthetic group which functions in electron transfers.

Additional images
Flavin-Adenin-Dinukleotid Flavín adenín dinucleótido Flavine adénine dinucléotide FAD Flavin adenina dinucleotide Dinukleotyd flawinoadeninowy FAD