Reduktaser

Reduktaser, commonly referred to as reductases, are a broad group of enzymes that catalyze reduction reactions, transferring electrons and sometimes protons to substrates. In biochemistry, these enzymes typically use cofactors such as NADH, NADPH, FAD, or FMN to donate reducing equivalents. They are found across all domains of life and localize to diverse cellular compartments, including the cytosol, mitochondria, and endoplasmic reticulum.

Reduktaser are often classified by their preferred electron donor or cofactor. NAD(P)H-dependent reductases use NADH or NADPH as the electron source, and include families such as aldo-keto reductases (AKRs) and short-chain dehydrogenases/reductases (SDRs). Flavin-dependent reductases rely on flavin cofactors (FAD or FMN) to mediate electron transfer, while other metal-dependent reductases utilize metal ions to catalyze reductions. This diversity allows reductases to act on a wide range of substrates.

Typical substrates include carbonyl compounds (reducing ketones and aldehydes to alcohols), nitro groups (nitroreductases reducing nitro to amino groups), and quinones (quinone reductases converting them to hydroquinones). Mechanistically, many reductases perform hydride transfer from NAD(P)H to the substrate within the active site, although some use alternative one- or two-electron transfer pathways.

Physiological roles of reductases include participation in metabolism, detoxification of xenobiotics, activation or deactivation of pharmaceutical compounds, and synthesis of natural products. They contribute to redox balance and can influence drug efficacy and resistance. Due to their specificity and stereoselectivity, reductases are also exploited in industrial biocatalysis for the production of chiral alcohols and other reduced compounds.