In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually utilizes NADP+ or NAD+ as cofactors. Transmembrane oxidoreductases create electron transport chains in bacteria, chloroplasts and mitochondria, including respiratory complexes I, II and III. Some others can associate with biological membranes as peripheral membrane proteins or be anchored to the membranes through a single transmembrane helix.
5α-Reductases, also known as 3-oxo-5α-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in three metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism. There are three isozymes of 5α-reductase encoded by the genes SRD5A1, SRD5A2, and SRD5A3.
3β-Hydroxysteroid dehydrogenase/Δ5-4 isomerase (3β-HSD) is an enzyme that catalyzes the biosynthesis of the steroid progesterone from pregnenolone, 17α-hydroxyprogesterone from 17α-hydroxypregnenolone, and androstenedione from dehydroepiandrosterone (DHEA) in the adrenal gland. It is the only enzyme in the adrenal pathway of corticosteroid synthesis that is not a member of the cytochrome P450 family. It is also present in other steroid-producing tissues, including the ovary, testis and placenta. In humans, there are two 3β-HSD isozymes encoded by the HSD3B1 and HSD3B2 genes.
Hydroxysteroid dehydrogenases (HSDs) are a group of alcohol oxidoreductases that catalyze the dehydrogenation of hydroxysteroids. These enzymes also catalyze the reverse reaction, acting as ketosteroid reductases (KSRs).
In enzymology, a cholest-5-ene-3β,7α-diol 3β-dehydrogenase (EC 1.1.1.181) is an enzyme that catalyzes the chemical reaction
In enzymology, a 4-oxoproline reductase (EC 1.1.1.104) is an enzyme that catalyzes the chemical reaction
In enzymology, a 12alpha-hydroxysteroid dehydrogenase (EC 1.1.1.176) is an enzyme that catalyzes the chemical reaction
In enzymology, a 16alpha-hydroxysteroid dehydrogenase (EC 1.1.1.147) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3alpha-hydroxysteroid dehydrogenase (A-specific) (EC 1.1.1.213) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3alpha(or 20beta)-hydroxysteroid dehydrogenase (EC 1.1.1.53) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3-keto-steroid reductase (EC 1.1.1.270) is an enzyme that catalyzes the chemical reaction
In enzymology, a 3-oxo-5beta-steroid 4-dehydrogenase is an enzyme that catalyzes the chemical reaction
In enzymology, a 6-hydroxynicotinate reductase is an enzyme that catalyzes the chemical reaction
In enzymology, a cholestenone 5alpha-reductase (EC 1.3.1.22) is an enzyme that catalyzes the chemical reaction
In enzymology, a cortisone alpha-reductase (EC 1.3.1.4) is an enzyme that catalyzes the chemical reaction
In enzymology, a progesterone 5alpha-reductase (EC 1.3.1.22) is an enzyme that catalyzes the chemical reaction
In enzymology, a NAD(P)H dehydrogenase (quinone) (EC 1.6.5.2) is an enzyme that catalyzes the chemical reaction
3-Oxo-5α-steroid 4-dehydrogenase 1 is an enzyme that in humans is encoded by the SRD5A1 gene. It is one of three forms of steroid 5α-reductase.
In enzymology, a steroid Δ5-isomerase is an enzyme that catalyzes the chemical reaction
5β-Reductase, or Δ4-3-oxosteroid 5β-reductase (EC 1.3.1.3, 3-oxo-Δ4-steroid 5β-reductase, androstenedione 5β-reductase, cholestenone 5β-reductase, cortisone 5β-reductase, cortisone Δ4-5β-reductase, steroid 5β-reductase, testosterone 5β-reductase, Δ4-3-ketosteroid 5β-reductase, Δ4-5β-reductase, Δ4-hydrogenase, 4,5β-dihydrocortisone:NADP+ Δ4-oxidoreductase, 3-oxo-5β-steroid:NADP+ Δ4-oxidoreductase) is an enzyme with systematic name 5β-cholestan-3-one:NADP+ 4,5-oxidoreductase. This enzyme catalyses the following chemical reaction
