Oxidoreductase

An oxidoreductase is an enzyme that catalyzes oxidation-reduction reactions, transferring electrons from a donor substrate to an acceptor. They are grouped in the class EC 1 of the Enzyme Commission nomenclature and participate in nearly all biological redox processes.

Oxidoreductases are diverse and are often categorized by the type of electron acceptor they use: dehydrogenases transfer electrons to NAD+ or NADP+; oxidases transfer electrons to molecular oxygen, sometimes forming water or hydrogen peroxide; oxygenases incorporate one or two atoms of oxygen into the substrate; peroxidases use hydrogen peroxide to oxidize substrates; reductases transfer electrons from donors such as NADPH to acceptors.

Many oxidoreductases employ cofactors that shuttle electrons, such as NAD+/NADH, NADP+/NADPH, flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), heme groups, iron-sulfur clusters. These cofactors cycle between reduced and oxidized states during catalysis. The active site architecture supports electron transfer and substrate binding; some enzymes are soluble, others are membrane-bound and participate in electron transport chains.

Functionally, oxidoreductases are central to energy production, metabolism, detoxification, and redox signaling. They enable respiration, photosynthesis, and various biosynthetic pathways. Biotechnological applications include the production of chiral chemicals, biosensors, and biocatalysis. Dysfunctions in redox enzymes are linked to diseases such as metabolic disorders and oxidative stress.