ISSN:
1432-2048
Keywords:
Key words:Δ5-3β-Hydroxysteroid dehydrogenase
;
Δ5-Δ4-Ketosteroid isomerase
;
Pregnenolone
;
Proges-terone
;
Short-chain dehydrogenase/reductases
;
Digitalis (cardenolide biosynthesis)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. Δ5-3β-Ηydroxysteroid dehydrogenase (Δ5-3β-HSD; EC 1.1.1.145), an enzyme converting pregn-5-ene-3β-ol-20-one (pregnenolone) to pregn-5-ene-3,20-dione (isoprogesterone), was isolated from the soluble fraction of suspension-cultured cells of Digitalis lanata L. strain VIII. Starting with acetone dry powder the enzyme was purified in three steps using column chromatography on Fractogel-TSK DEAE, hydroxyapatite and Sephacryl G-200. Fractions with highest Δ5-3β-HSD activity were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After in-situ digestion the resulting bands were sequenced N-terminally. The 29-kDa band yielded three fragments with high sequence homology to members of the superfamily of short-chain dehydrogenases/reductases. High similarity was found to microbial hydroxysteroid dehydrogenases. The band may therefore represent the Δ5-3β-HSD. The purified enzyme was characterized with respect to kinetic parameters, substrate specificity and localization. The function of the enzyme in steroid metabolism is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004250050751
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