Flavin adenine dinucleotide
(biochemistry) A redox cofactor in which riboflavin is the core component and is involved in various metabolic processes
In biochemistry, flavin adenine dinucleotide (FAD) is a cofactor in redox reactions. There are two main portions of FAD: (1) adenine and (2) flavin mononucleotide. The two portions are joined together at their phosphate groups. FAD occurs in different redox states: quinone, semiquinone, and hydroquinone. It converts from one state to another either by accepting or donating electrons. Quinone is the fully oxidized form of FAD. When it accepts two electrons (e-) and two protons (H+) it converts to the hydroquinone form, FADH2. FADH2 can convert to FADH when it losses one H+ and one e-, and losing another H+ and one e- reverts it to FAD. FAD can be produced by the reduction and dehydration of flavin-N(5)-oxide.1
FAD contained in proteins make flavoproteins. Flavoproteins are proteins containing a flavin moiety, e.g. FAD and flavin mononucleotide. Flavoproteins are involved in different biological processes, such as DNA repair, removal of free radicals, bioluminescence, and photosynthesis.
Chemical formula: C27H33N9O15P2
Abbreviation / Acronym: FAD
1 Devlin, edited by Thomas M. (2011). Textbook of biochemistry: with clinical correlations (7th ed.). Hoboken, NJ: John Wiley & Sons.