Oxidoreductase

An oxidoreductase is an enzyme that catalyzes an oxidation-reduction, or redox, reaction. In these reactions, one chemical species is oxidized by losing electrons or increasing its oxidation state, while another is reduced by gaining electrons or decreasing its oxidation state. Oxidoreductases make up enzyme class EC 1 in the Enzyme Commission classification system .^1,2

Oxidoreductases transfer electrons or reducing equivalents between an electron donor and an electron acceptor. Depending on the particular enzyme, acceptors can include NAD⁺, NADP⁺, oxygen, quinones, cytochromes, disulfides, and other molecules. Because donors and acceptors vary widely, oxidoreductases participate in many different biochemical pathways rather than performing a single metabolic function .¹

Several familiar enzyme names describe types of oxidoreductases. Dehydrogenases commonly transfer reducing equivalents or electrons from a substrate to an acceptor such as NAD⁺. Oxidases use molecular oxygen as an electron acceptor, while reductases are typically named for the substrate they reduce. Oxygenases catalyze reactions in which one or more oxygen atoms from molecular oxygen are incorporated into a substrate .^1,2

Oxidoreductase is therefore the broad enzyme-class term, whereas names such as dehydrogenase, oxidase, reductase, and oxygenase describe enzymes performing particular kinds of redox chemistry. Systematic oxidoreductase names generally identify the electron donor and acceptor involved in the reaction .¹