Publications

• Study of 3 alpha, 20 beta-hydroxysteroid dehydrogenase with an enzyme-generated affinity alkylator: dual enzyme activity at a single active site.

  Strickler R.C., Covey D.F., Tobias B.

  The substrate 17 beta-[(1S)-1-hydroxy-2-propynyl]-androst-4-en-3-one (beta-HPA) and its enzyme-generated alkylating product 17 beta-(1-oxo-2-propynyl)androst-4-en-3-one (OPA) were synthesized to investigate the relationship between the 3 alpha and 20 beta activities observed in commercially availa ... >> More

  The substrate 17 beta-[(1S)-1-hydroxy-2-propynyl]-androst-4-en-3-one (beta-HPA) and its enzyme-generated alkylating product 17 beta-(1-oxo-2-propynyl)androst-4-en-3-one (OPA) were synthesized to investigate the relationship between the 3 alpha and 20 beta activities observed in commercially available cortisone reductase (EC 1.1.1.53) from Streptomyces hydrogenans. beta-HPA, a substrate [apparent Km = 145 microM; Vmax = 63 nmol (min microgram)-1], when enzymatically oxidized by cortisone reductase of OPA, inactivates simultaneously the 3 alpha and 20 beta activities in a time-dependent and irreversible manner following pseudo-first-order kinetics. OPA alone, an affinity alkylating steroid (KI = 40.5 microM; k3 = 1.8 X 10(-2) S-1), simultaneously inactivates 3 alpha and 20 beta activities in a time-dependent and irreversible manner. At pH 7, the t 1/2 of enzyme inactivation for beta-HPA (10 h) or OPA (41 min) is slower than at pH 9.2 (beta-HPA, 16 min, and OPA, 3.3 min). Substrates (progesterone, 20 beta-hydroxypregn-4-en-3-one, and 5 alpha-dihydrotestosterone), but not all steroids (20 al]ha-delta 4-pregn-4-en-3-one and 17 beta-estradiol), protect against loss of both enzyme activities by beta-HPA and OPA. The alpha isomer of HPA is not enzymatically oxidized and therefore does not cause inactivation of either 3 alpha or 20 alpha activity. Thus, beta-HPA functions as a substrate for the enzymatic generation of a powerful affinity alkylator of cortisone reductase. Second, the identical change in both the 3 alpha and 20 beta activities in all experimental conditions clearly results from dual enzyme activity at a single enzyme active site. << Less

  Biochemistry 19:4950-4954(1980) [PubMed] [EuropePMC]

• Bifunctional enzyme activity at the same active site: study of 3 alpha and 20 beta activity by affinity alkylation of 3 alpha, 20 beta-hydroxysteroid dehydrogenase with 17-(bromoacetoxy)steroids.

  Sweet F., Samant B.R.

  Biochemistry 19:978-986(1980) [PubMed] [EuropePMC]

• [20 beta-Hydroxysteroid dehydrogenase. 2. Preparation and crystallization].

  HUEBENER H.J., SAHRHOLZ F.G.

  Biochem Z 333:95-105(1960) [PubMed] [EuropePMC]

• [20 beta-Hydroxysteroid dehydrogenase, a new crystalline enzyme].

  HUEBENER H.J., SAHRHOLZ F.G., SCHMIDT-THOME J., NESEMANN G., JUNK R.

  Biochim Biophys Acta 35:270-272(1959) [PubMed] [EuropePMC]

• Comparison of the 3alpha-and 20beta-hydroxysteroid dehydrogenase activities of the cortisone reductase of Streptomyces hydrogenans.

  Edwards C.A., Orr J.C.

  The 3alpha- and 20beta-hydroxysteroid dehydrogenase (HSD) activities of cortisone reductase in Streptomyces hydrogenans have been examined to determine whether both activities are due to one enzyme. This question was raised when changes in the commercial preparations of the enzyme reduced the 3alp ... >> More

  The 3alpha- and 20beta-hydroxysteroid dehydrogenase (HSD) activities of cortisone reductase in Streptomyces hydrogenans have been examined to determine whether both activities are due to one enzyme. This question was raised when changes in the commercial preparations of the enzyme reduced the 3alpha-HSD activity to 5% of its original level while retaining full 20beta-HSD activity. In our experiments, the enzyme was purified to crystallinity and partially characterized. The 3alpha- and 20beta-HSD activities were both coinduced and copurified. The 3alpha- and 20beta-HSD activities were compared using the crystalline enzyme for studies of substrate competition, thermal inactivation at 52 degrees C, loss of activity with three haloacetoxysteroids, and the effects of Me2SO and temperature on the reaction rate. These studies support the conclusion that the 3alpha- and 20beta-HSD activities are due to the same enzyme molecule. In addition, it appears that the binding sites for the two activities do not act independently. << Less

  Biochemistry 17:4370-4376(1978) [PubMed] [EuropePMC]