NQO1 Holo Form

**NQO1** (NQO1, EC 1.6.5.2) is a dimeric, two-domain FAD-dependent enzyme which catalyses the two electron reduction of quinones and related substrates through an enzyme-substituted mechanism in which NAD(P)H enters the active site, reduces the FAD and exits as the oxidised form, allowing the subsequent substrate binding and reduction by the FADH2. Primarily, NQO1 avoids the formation of reactive semiquinones, maintains antioxidants such as α-tocopherol and ubiquinone in their reduced state and also activates some anticancer bioreductive drugs. Additionally, NQO1 interacts with tumour suppressors such as p53 and p73 and stabilizes them towards proteasomal degradation while its interaction with the 20S proteasome prevents the degradation of a plethora of proteins with intrinsically disordered regions, including several cell cycle regulators, tumor suppressors and apoptotic protei. The study of NQO1 polymorphisms is particulary interesting due to its enhanced expression in several types of **cancer**.