1.6.3.1 NAD(P)H + H+ + O2 = NAD(P)+ + H2O2 model of electron transport from NADPH to the terminal electron acceptor O2 1.6.3.1 NAD(P)H + H+ + O2 = NAD(P)+ + H2O2 flavoprotein 1.6.3.1 NAD(P)H + H+ + O2 = NAD(P)+ + H2O2 Requires FAD, heme and calcium. When calcium is present, this transmembrane glycoprotein generates H2O2 by transfering electrons from intracellular NAD(P)H to extracellular molecular oxygen. The electron bridge within the enzyme contains one molecule of FAD and probably two heme groups. This flavoprotein is expressed at the apical membrane of thyrocytes, and provides H2O2 for the thyroid peroxidase-catalysed biosynthesis of thyroid hormones 1.6.3.1 NAD(P)H + H+ + O2 = NAD(P)+ + H2O2 in stable conformation, the active site adopts a closed conformation not allowing the substrate to bind. In presence of urea, an open conformation of the active site with 0.9 nm distance between the indole ring of W47 and the isoalloxazine ring of FMN412 is favored 1.6.3.1 NAD(P)H + H+ + O2 = NAD(P)+ + H2O2 a cytosolic C-terminal dehydrogenase domain includes an FAD cofactor and an NADPH substrate binding site. On activation, electrons are transferred from NADPH to FAD and across the membrane, via heme irons, to molecular oxygen, thus producing superoxide anion, which can be dismutated into hydrogen peroxide