Translations:Flavin adenine dinucleotide/7/en

FAD can be reduced to FADH₂ through the addition of 2 H⁺ and 2 e⁻. FADH₂ can also be oxidized by the loss of 1 H⁺ and 1 e⁻ to form FADH. The FAD form can be recreated through the further loss of 1 H⁺ and 1 e⁻. FAD formation can also occur through the reduction and dehydration of flavin-N(5)-oxide. Based on the oxidation state, flavins take specific colors when in aqueous solution. flavin-N(5)-oxide (superoxidized) is yellow-orange, FAD (fully oxidized) is yellow, FADH (half reduced) is either blue or red based on the pH, and the fully reduced form is colorless. Changing the form can have a large impact on other chemical properties. For example, FAD, the fully oxidized form is subject to nucleophilic attack, the fully reduced form, FADH₂ has high polarizability, while the half reduced form is unstable in aqueous solution.FAD is an aromatic ring system, whereas FADH₂ is not. This means that FADH₂ is significantly higher in energy, without the stabilization through resonance that the aromatic structure provides. FADH₂ is an energy-carrying molecule, because, once oxidized it regains aromaticity and releases the energy represented by this stabilization.