Title: Nad-dependent 3α- and 12α-hydroxysteroid dehydrogenase activities from eubacterwm lentum atcc no. 25559
Abstract: Eubacterium lentum (ATCC No. 25559) was shown to contain 3α- and 12α-hydroxysteroid dehydrogenases both of which were NAD-dependent and active against conjugated and unconjugated bile salts. In addition, the 3α-hydroxysteroid dehydrogenase was active against members of the Androstan series containing a 3α-hydroxyl group regardless of the stereo-orientation of the 5-H. No measurable activity against 7α-, 7β-, 11β-, or 17β-hydroxyl groups was demonstrated. The growth of E. lentum and the production of 3α- and 12α-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 > 0.75%. The 12α-hydroxysteroid dehydrogenase was heat labile and could be selectively inactivated by heating at 50°C for 45 min. Both the heated enzyme preparation (containing only 3α-hydroxysteroid dehydrogenase) and the unheated enzyme preparation (containing 3α- and 12α-hydroxysteroid dehydrogenases) were useful in the spectrophotometric quantification of bile salts. The optimal pH values for 3α- and 12α-hydroxysteroid dehydrogenases were 11.3 and 10.2, respectively. Kinetic studies have Km estimates of 2 · 10−5 M and 1.0 · 10−5 M with 3α,7α-dihydroxy-5β-cholanoyl glycine and 7α,12α-dihydroxy-5β-cholanoate for the two respective enzymes.
Publication Year: 1977
Publication Date: 1977-12-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 45
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