Dioxygen (molecular oxygen) (O₂)

Dioxygen (O₂), also called molecular oxygen, is an essential, diatomic gas that acts as a vital cofactor and electron acceptor in a vast range of biological and enzymatic reactions. It serves as a substrate for numerous enzymes, particularly oxygenases (monooxygenases and dioxygenases), that incorporate oxygen atoms into organic substrates, fundamental for energy metabolism, biosynthesis, and detoxification. Although critical to cellular life, improper oxygen handling leads to the production of reactive oxygen species (ROS), implicated in both normal cell signaling and pathological oxidative stress[5]. Dioxygen is therefore not a drug target per se but is indispensable as a cofactor for enzymatic catalysis across many biological systems[1][2][3][4][5][6][8].

Other names

Molecular oxygenO₂dioxygenoxygen (gas)oxygen cofactor

Cofactor and electron acceptor in enzymatic oxidation (e.g., binds to enzyme active sites, participates in dioxygenation/monooxygenation of substrates)[2][4] Oxygenation of organic and inorganic molecules in diverse enzyme-catalyzed reactions[2][4]