- 4 Downloads
NADPH (nicotinamide adenine dinucleotide phosphate) oxidase (EC 126.96.36.199) is an enzyme that produces superoxide anions by transferring electrons from reduced NADPH (the electron donor) to oxygen (O2). In the reaction, each NADPH molecule donates two electrons, which reduce two oxygen molecules, respectively, yielding two superoxide anions. NADPH oxidase is not a single protein but a multi-subunit protein complex (Babior 2004). While the term NADPH oxidase generally refers to such a protein complex, sometimes it is also ambiguously used to describe the catalytic subunit of the enzyme (aka the NOX subunit). The NADPH oxidase family contains different isoforms of the catalytic subunit, which may differ in the enzyme composition, subcellular localization, expression patterns, and/or biochemical properties. Some isoforms of NADPH oxidase produce hydrogen peroxide instead of superoxide.