redüktaz

Redüktaz, or reductase enzymes, form a broad group of biological catalysts that catalyze reduction reactions in which substrates gain electrons, typically as a hydride from nicotinamide adenine dinucleotide (NADH) or NADPH. Most reductases utilize NADH/NADPH as electron donors, or flavin cofactors like FAD or FMN, and may require other cofactors or metal centers. They are found in many cellular compartments and participate in a wide range of metabolic and detoxification processes.

Redüktaz participate in diverse pathways, including nucleotide and amino acid synthesis, lipid metabolism, and xenobiotic detoxification. Notable examples include dihydrofolate reductase (DHFR), which reduces dihydrofolate to tetrahydrofolate in one-carbon metabolism; aldo-keto reductases (AKR) and the short-chain dehydrogenase/reductase (SDR) family, which catalyze reductions of aldehydes and ketones to alcohols; and nitroreductases that reduce nitro groups in various compounds. Mechanistically, reductases often operate via hydride transfer from NAD(P)H to the substrate, sometimes with assistance from flavin cofactors that shuttle electrons. They can be cytosolic or membrane-associated, and their activity is influenced by cellular redox state and cofactor availability.

Clinical and biotechnological relevance: reductases are targets for pharmaceuticals; DHFR inhibitors such as methotrexate and trimethoprim block nucleotide synthesis in cancer cells and bacteria, respectively. Altered reductase activity can influence drug metabolism, resistance, and toxin susceptibility. In biotechnology, reductases enable stereoselective reductions crucial for producing chiral alcohols and other fine chemicals.