dehydrogenaasi

Dehydrogenaasi, commonly called dehydrogenase in English, are enzymes in the oxidoreductase family that catalyze oxidation–reduction reactions in which a substrate loses hydrogen. The reaction typically transfers a hydride to an electron acceptor such as NAD+ or NADP+, or to flavin cofactors such as FAD, or to ubiquinone. Dehydrogenases are widespread in metabolism and can be located in the cytosol or in organelles such as mitochondria.

They vary in substrate and cofactor specificity and are categorized by the EC system. For example, many enzymes that act on the CH-OH group of donors are in EC 1.1.x.x, and NAD+-dependent dehydrogenases commonly fall under EC 1.1.1.x. Some are NAD+-dependent, others NADP+-dependent, and some transfer electrons to the respiratory chain via FAD or FMN.

Prominent examples include lactate dehydrogenase (LDH), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), malate dehydrogenase, and alcohol dehydrogenase. Dehydrogenases participate in core pathways such as glycolysis, the citric acid cycle, the pentose phosphate pathway, fatty acid oxidation, and amino acid metabolism.

Clinical and industrial relevance: altered dehydrogenase activity or imbalances in cofactors can be associated with metabolic disorders; certain dehydrogenases serve as biomarkers. In biotechnology, dehydrogenases are used as biocatalysts and in biosensors, and NADH/NADPH recycling is important for enzymatic synthesis and other processes.