5α-reductase http://purl.bioontology.org/ontology/MESH/D013741 http://purl.bioontology.org/ontology/MESH/D042944 http://purl.obolibrary.org/obo/NCIT_C17190 https://en.wikipedia.org/wiki/5%CE%B1-Reductase https://enzyme.expasy.org/EC/1.3.1.22 https://enzyme.expasy.org/EC/1.3.99.5 https://www.wikidata.org/wiki/Q143333 3-oxo-5-alpha-steroid 4-dehydrogenase 3-oxo-5α-steroid 4-dehydrogenase 5-alpha reductase 5-alpha-reductase 5α-reductases An enzyme that catalyzes the reduction of testosterone to 5α-dihydrotestosterone. An oxidoreductase that catalyzes the conversion of 3-oxo-Δ4 steroids into their corresponding 5α form. It plays an important role in the conversion of testosterone into dihydrotestosterone and progesterone into dihydroprogesterone. cholestenone 5-alpha-reductase oxidoreductase which acts on CH-CH group donors