FADcontaining

FADcontaining refers to molecules, especially proteins, that incorporate flavin adenine dinucleotide (FAD) as a prosthetic group or tightly bound cofactor. FAD is a flavin cofactor derived from riboflavin (vitamin B2) and can cycle between oxidized (FAD), semiquinone (FADH•), and reduced (FADH2) states, enabling one- and two-electron transfers in enzymatic redox reactions. In FADcontaining proteins, this chemistry supports a broad set of catalytic strategies and often links substrate oxidation to downstream electron carriers such as NAD+, ubiquinone, or molecular oxygen.

FADcontaining enzymes include a large and diverse family known as flavoproteins. Examples include succinate dehydrogenase (mitochondrial Complex II) in the respiratory chain, glucose oxidase, various acyl-CoA dehydrogenases, and certain monooxygenases and luciferases. In many cases the FAD moiety is covalently or noncovalently bound to the protein, and the binding mode influences redox potential, spectral properties, and turnover.

Functionally, FADcontaining proteins participate in energy metabolism, oxidative stress defense, lipid and amino acid catabolism, and xenobiotic detoxification. Regeneration of the oxidized form of FAD within these enzymes occurs via cellular redox systems, allowing continuous turnover of substrates. Thus, FADcontaining proteins are central to cellular respiration, metabolism, and signaling.

Defects in FAD-dependent enzymes can contribute to metabolic disorders and disease states, illustrating the biological importance of this cofactor. FADcontaining is a defining class among flavoproteins, alongside other cofactors such as FMN and riboflavin-derived enzymes.