@article{oai:kanazawa-u.repo.nii.ac.jp:00053803,
 author = {板垣, 英治 and Itagaki, Eiji and Iwaya, Teturou},
 issue = {6},
 journal = {The Journal of Biochemistry},
 month = {},
 note = {An NAD+-linked 17β-hydroxysteroid dehydrogenase was purified to homogeneity from a fungus, Cylindrocarpon radicicola ATCC 11011 by ion exchange, gel filtration, and hydrophobic chromatographies. The purified preparation of the dehydrogenase showed an apparent molecular weight of 58, 600 by gel filtration and polyacrylamide gel electropho-resis. SDS-gel electrophoresis gave Mr=26, 000 for the identical subunits of the protein. The amino-terminal residue of the enzyme protein was determined to be glycine. The enzyme catalyzed the oxidation of 17β-hydroxysteroids to the ketosteroids with the reduction of NAD+, which was a specific hydrogen acceptor, and also catalyzed the reduction of 17-ketosteroids with the consumption of NADH. The optimum pH of the dehydrogenase reaction was 10 and that of the reductase reaction was 7.0. The enzyme had a high specific activity for the oxidation of testosterone (Vmax=85 μmol/min/mg; Km for the steroid =9.5 μM; Km for NAD+=198 μM at pH 10.0) and for the reduction of androstenedione (Vmax=1.8 μmol/min/mg; Km for the steroid=24 μM; Km for NADH=6.8 μM at pH 7.0). In the purified enzyme preparation, no activity of 3α-hydroxysteroid dehydrogenase, 3β-hydroxysteroid dehydrogenase, Δ5-3-ketosteroid-4, 5-isomerase, or steroid ring A-Δ-dehydrogenase was detected. Among several steroids tested, only 17β-hydroxysteroids such as testosterone, estradiol-17β, and 11β-hydroxytestosterone, were oxidized, indicating that the enzyme has a high specificity for the substrate steroid. The stereospecificity of hydrogen transfer by the enzyme in dehydrogenation was examined with [17α-3H] testosterone.},
 pages = {1039--1044},
 title = {Purification and Characterization of 17β-Hydroxysteroid Dehydrogenase from Cylindrocarpon radicicola},
 volume = {103},
 year = {1988}
}