Stimulation of 16-dehydroprogesterone and progesterone reductases of Eubacterium sp. strain 144 by hemin and hydrogen or pyruvate.
Suspensions of Eubacterium sp. strain 144, prepared from cells grown with 16-dehydroprogesterone, catalyzed the reduction of this steroid to 17-isoprogesterone at a very low rate. Modifications of the assay to optimize the pH (5.5) and increase the steroid solubility (10% [vol/vol] methanol) did not significantly enhance the reaction. However, growth of strain 144 in the presence of hemin was found to stimulate 16-dehydroprogesterone reductase during the initial 30 min of incubation, giving a biphasic time course. These biphasic kinetics could be eliminated by providing the cells with an exogenous electron donor. Strain 144 used either H2 or pyruvate for this purpose, and 17-isoprogesterone formation was nearly complete after 20 to 30 min of incubation. However, under these conditions, strain 144 further converted 17-isoprogesterone to products which lacked UV absorbance (254 nm). When progesterone was used as a substrate, it was found that strain 144 could reduce the C4-C5 double bond of this steroid by a progesterone reductase to give mostly 5 beta-pregnadione and some 5 alpha-pregnadione. Furthermore, the 3-keto group of 5 beta-pregnadione steroid was also reduced to a hydroxy function. The maximum activities of both 16-dehydroprogesterone and progesterone reductases in cell suspensions required the growth of strain 144 with hemin and 16-dehydroprogesterone and the presence of H2 or pyruvate.
D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis*; D002021:Buffers; D005051:Eubacterium / Q000201:enzymology*; D006418:Heme / Q000031:analogs & derivatives*; D006427:Hemin / Q000494:pharmacology*; D006859:Hydrogen / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D011374:Progesterone / Q000031:analogs & derivatives* / Q000378:metabolism; D011375:Progesterone Reductase / Q000032:analysis*; D011773:Pyruvates / Q000494:pharmacology*; D019289:Pyruvic Acid
D002021:Buffers; D011773:Pyruvates; D006418:Heme; D011374:Progesterone; D006427:Hemin; D006859:Hydrogen; D019289:Pyruvic Acid; D015096:3-Hydroxysteroid Dehydrogenases; D011375:Progesterone Reductase; C028106:16-dehydroprogesterone