Flavin adenine dinucleotide FADH

FADH, Flavine adenine dinucleotide (reduced form)... 

FADH , flavin adenine dinucleotide, fully reduced ... 

FADH% flavin adenine dinucleotide, neutral semiquinone radical FAD" , flavin adenine dinucleotide, anion semiquinone radical FMN, flavin mononucleotide ... 

In the second stage, the building blocks are degraded by various pathways in tissues to a common metabolic intermediate, acetyl CoA. Most of the energy contained in metabolic fuels is conserved in the chemical bonds (electrons) of acetyl CoA. A smaller portion is conserved in reducing nicotinamide adenine dinucleotide (NAD) to NADH or flavin adenine dinucleotide (FAD) to FADH. Reduction indicates the addition of electrons that may be free, part of a hydrogen atom (H), or a hydride ion (H ). 

CoQ Coenzyme Q FADH- Radical form of reduced flavin adenine dinucleotide... 

The purified E. coli protein has a molecular weight of 49 kD. It does not require any divalent cation for activity. It contains two different noncovalently bound chromophores that absorb light. One chromophore is flavin adenine dinucleotide (FADH- or FADH2). The other is 5,10-methenyltetrahydrofolyl polyglutamate (MTHF). The absorption of light by the chromophores is essential for the enzymatic reversal of the pyrimidine dimer back to the original pyrimidine monomers. However,... 

Introduction of a double bond. The /3-oxidation pathway begins when fatty acid forms a thiol ester with coenzyme A to give a fatty acyl CoA. Two hydrogen atoms are then removed from carbons 2 and 3 by an acyl CoA dehydrogenase enzyme to yield an ,/3-unsaturated acyl CoA. This kind of oxidation—the introduction of a conjugated double bond into a carbonyl compound—occurs frequently in biochemical pathways and is usually carried out by the coenz5nne flavin adenine dinucleotide (FAJ ). Reduced FADH is the by-product. 

Photoreactivating enzyme contains two chromophores. (A chromophore is a structural moiety that absorbs light of characteristic wavelengths.) One chromophore is flavin adenine dinucleotide in the reduced state, FADH". The second chromophore in some photolyases is 5,10-methenyltetrahydrofolate and in others is 8-hydroxy-5-deazaflavin. 

Another important electron acceptor is FAD (flavin adenine dinucleotide) (Figure 15.4), which is the oxidized form of FADH. The symbol FADH explicitly recognizes that protons (hydrogen ions) as well as electrons are accepted by FAD. The structures shown in this equation again point out the electrons that are transferred in the reaction. Several other coenzymes contain the flavin group they are derived from the vitamin riboflavin (vitamin B ). 

---