Document Detail

Oxidation of primary bile acids by a 7 alpha-hydroxysteroid dehydrogenase elaborating Clostridium bifermentans soil isolate.
MedLine Citation:
PMID:  3480039     Owner:  NLM     Status:  MEDLINE    
A gram-positive, rod-shaped anaerobe (strain F-6) was isolated from soil. This organism was identified by cellular morphology as well as fermentative and biochemical data as Clostridium bifermentans. Strain F-6 formed 7-ketolithocholic acid from chenodeoxycholic acid and 7-ketodeoxycholic acid from cholic acid in whole cell cultures, but did not transform deoxycholic acid, ursodeoxycholic acid, or ursocholic acid. This reaction is reversible. The structures of 7-ketolithocholic acid and 7-ketodeoxycholic acid were verified by mass spectroscopy and by thin-layer chromatography using Komarowsky's spray reagent. When incubated with the strain F-6 glycine and taurine conjugates of the primary bile acids were partially hydrolyzed and transformed to 7-keto products. Optimal yields of 7-ketolithocholic acid and 7-ketodeoxycholic acid were obtained after 78 h of incubation. Culture pH changed with time and was characterized by an initial drop (1.1 pH units) and a gradual increase back to the starting pH (7.3). Corroborating these observations, an inducible, NADP-dependent, 7 alpha-hydroxysteroid dehydrogenase was demonstrated in cell extracts of strain F-6. A trace of NAD-dependent 7 alpha-hydroxysteroid dehydrogenase was also found. A substantial increase in the specific activity of the NADP-dependent 7 alpha-hydroxysteroid dehydrogenase was observed when either 7-ketolithocholic acid, chenodeoxycholic acid, or deoxycholic acid was included in the growth medium. Optimal induction of the NADP-dependent 7 alpha-hydroxysteroid dehydrogenase was achieved with 0.3-0.4 mM 7-ketolithocholic acid. Production of the enzyme(s) was optimal at 6-8 h of growth and the 7 alpha-hydroxysteroid dehydrogenases had a pH optimum of approximately 11.(ABSTRACT TRUNCATED AT 250 WORDS)
J D Sutherland; C N Williams; D M Hutchison; L V Holdeman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of microbiology     Volume:  33     ISSN:  0008-4166     ISO Abbreviation:  Can. J. Microbiol.     Publication Date:  1987 Aug 
Date Detail:
Created Date:  1988-01-25     Completed Date:  1988-01-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372707     Medline TA:  Can J Microbiol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  663-9     Citation Subset:  IM    
Department of Medicine, Dalhousie University, Halifax, NS, Canada.
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MeSH Terms
Bile Acids and Salts / metabolism*
Chromatography, Affinity
Clostridium / enzymology*,  growth & development
Hydrogen-Ion Concentration
Hydroxysteroid Dehydrogenases / isolation & purification,  metabolism*
Soil Microbiology*
Reg. No./Substance:
0/Bile Acids and Salts; EC 1.1.-/Hydroxysteroid Dehydrogenases; EC alpha-hydroxysteroid dehydrogenase

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