title: NAD-dependent 3alpha- and 12alpha-hydroxysteroid dehydrogenase activities from Eubacterium lentum ATCC no. 25559.
abstract: Eubacterium lentum (ATCC No. 25559) was shown to contain 3alpha-and 12alpha-hydroxysteroid dehydrogenases both of which were NAD-dependent and active against conjugated and unconjugated bile salts. In addition, the 3alpha-hydroxysteroid dehydrogenase was active against members of the Androstan series containing a 3alpha-hydroxyl group regardless of the stereo-orientation of the 5-H-. No measurable activity against 7alpha-, 7beta-, 11beta-, or 17beta-hydroxyl groups was demonstrated. The growth of E. lentum and the production of 3alpha- and 12alpha-hydroxysteroid dehydrogenases were greatly enhanced by the addition of L-, D- or DL-arginine to the medium. Yields of hydroxysteroid dehydrogenase were optimal in the range of 0.50-0.75% arginine; however, the growth of the organisms was further enhanced at arginine concentrations greater than 0.75%. The 12alpha-hydroxysteroid dehydrogenase was heat labile and could be selectively inactivated by heating at 50 degrees C for 45 min. Both the heated enzyme preparation (containing only 3alpha-hydroxysteroid dehydrogenase) and the unheated enzyme preparation (containing 3alpha- and 12alpha-hydroxysteroid dehydrogenases) were useful in the spectrophotometric quantification of bile salts. The optimal pH values for 3alpha- and 12alpha-hydroxysteroid dehydrogenases were 11.3 and 10.2, respectively. Kinetic studies have Km estimates of 2.10(-5) M and 1.0.10(-4) M with 3alpha,7alpha-dihydroxy-5beta-cholanoyl glycine and 7alpha,12alpha-dihydroxy-5beta-cholanoate for the two respective enzymes.
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D001120:Arginine / Q000494:pharmacology; D001647:Bile Acids and Salts / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D005051:Eubacterium / Q000201:enzymology* / Q000502:physiology; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007700:Kinetics; D009243:NAD
chemical_list: D001647:Bile Acids and Salts; D009243:NAD; D001120:Arginine; D015096:3-Hydroxysteroid Dehydrogenases; D006913:Hydroxysteroid Dehydrogenases