5β-Reductase explained

Δ^4-3-Oxosteroid 5β-reductase
Ec Number:	1.3.1.3
Cas Number:	2604034

5β-Reductase, or Δ⁴-3-oxosteroid 5β-reductase (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.^{[1] [2] [3] [4] [5] [6] [7] [8] [9]} This enzyme catalyses the following chemical reaction

(1) 5β-cholestan-3-one + NADP⁺

\rightleftharpoons cholest-4-en-3-one + NADPH + H⁺

(2) 17,21-dihydroxy-5β-pregnane-3,11,20-trione + NADP⁺

\rightleftharpoons cortisone + NADPH + H⁺

The human enzyme efficiently acts on progesterone, 17α-hydroxyprogesterone, androstenedione, and testosterone to 5β-reduced metabolites. It can also act on aldosterone, corticosterone and cortisol, to some extent.

See also

• 5α-Reductase
• Steroidogenic enzyme

Notes and References

1. Dorfman RI, Forchielli E . Separation of delta 4-5 alpha-hydrogenases from rat liver homogenates . The Journal of Biological Chemistry . 223 . 1 . 443–8 . November 1956 . 13376613 .
2. Brown-Grant K, Forchielli E, Dorfman RI . The delta4-hydrogenases of guinea pig adrenal gland . The Journal of Biological Chemistry . 235 . 1317–20 . May 1960 . 13805063 .
3. Enzymatic introduction of double bonds into steroid ring A . Levy, H.R. . Talalay, P. . amp . J. Am. Chem. Soc. . 1957 . 79 . 10 . 2658–2659 . 10.1021/ja01567a089.
4. Tomkins GM . The enzymatic reduction of delta 4-3-ketosteroids . The Journal of Biological Chemistry . 225 . 1 . 13–24 . March 1957 . 13416214 .
5. Sugimoto Y, Yoshida M, Tamaoki B . Purification of 5 beta-reductase from hepatic cytosol fraction of chicken . The Journal of Steroid Biochemistry and Molecular Biology . 37 . 5 . 717–24 . December 1990 . 2278855 . 10.1016/0960-0760(90)90356-p . 54431282 .
6. Furuebisu M, Deguchi S, Okuda K . Identification of cortisone 5 beta-reductase as delta 4-3-ketosteroid 5 beta-reductase . Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology . 912 . 1 . 110–4 . March 1987 . 3828348 . 10.1016/0167-4838(87)90253-6 .
7. Okuda A, Okuda K . Purification and characterization of delta 4-3-ketosteroid 5 beta-reductase . The Journal of Biological Chemistry . 259 . 12 . 7519–24 . June 1984 . 6736016 .
8. Charbonneau A, The VL . Genomic organization of a human 5beta-reductase and its pseudogene and substrate selectivity of the expressed enzyme . Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression . 1517 . 2 . 228–35 . January 2001 . 11342103 . 10.1016/s0167-4781(00)00278-5 .
9. Kondo KH, Kai MH, Setoguchi Y, Eggertsen G, Sjöblom P, Setoguchi T, Okuda KI, Björkhem I . Cloning and expression of cDNA of human delta 4-3-oxosteroid 5 beta-reductase and substrate specificity of the expressed enzyme . European Journal of Biochemistry . 219 . 1–2 . 357–63 . January 1994 . 7508385 . 10.1111/j.1432-1033.1994.tb19947.x . free .