Dehydrogenase

A dehydrogenase is an enzyme that catalyzes an oxidation-reduction reaction in which a substrate is oxidized and electrons, often transferred together with hydrogen, are passed to an electron acceptor. Dehydrogenases belong to the broad enzyme class called oxidoreductases. Many use cofactors such as NAD⁺, NADP⁺, FAD, or FMN to accept reducing equivalents from the substrate .^1,2

In NAD⁺-dependent reactions, for example, oxidation of a substrate can be coupled to reduction of NAD⁺ to NADH. Flavin-dependent dehydrogenases commonly use enzyme-bound FAD or FMN to receive electrons. Individual dehydrogenases are often named partly for the substrate they act on, such as alcohol dehydrogenase, lactate dehydrogenase, or succinate dehydrogenase .^1,2

Dehydrogenases participate throughout metabolism. Succinate dehydrogenase, for example, oxidizes succinate to fumarate while transferring electrons through enzyme-bound FAD and ultimately to ubiquinone. Other dehydrogenases generate NADH or NADPH, allowing electrons removed from one molecule to participate in later metabolic reactions .²

The term dehydrogenase does not mean that molecular hydrogen must be released. It refers to enzymes that transfer reducing equivalents during redox reactions. Dehydrogenases are also distinct from oxidases: oxidases use molecular oxygen as an electron acceptor, whereas dehydrogenases typically transfer electrons to other acceptors .¹