Journal of Lipid Research, Vol 20, 325-333, Copyright © 1979 by Lipid Research, Inc.

ARTICLES

7alpha-Dehydroxylation of cholic acid and chenodeoxycholic acid by Clostridium leptum

EJ Stellwag and PB Hylemon

The rate of 7alpha-dehydroxylation of primary bile acids was quantitatively measured radiochromatographically in anaerobically washed whole cell suspensions of Clostridium leptum. The pH optimum for the 7alpha-dehydroxylation of both cholic and chenodeoxycholic acid was 6.5-7.0. Substrate saturation curves were observed for the 7alpha- dehydroxylation of cholic and chenodeoxycholic acid. However, cholic acid whole cell K0.5 (0.37 micron) and V (0.20 mumol hr-1mg protein-1) values differed significantly from chenodeoxycholic acid whole cell K0.5 (0.18 micron) and V (0.50 mumol-1 hr-1 mg protein-1). 7alpha- Dehydroxylation activity was not detected using glycine and taurine- conjugated primary bile acids, ursodeoxycholic acid, cholic acid methyl ester, or hyocholic acid as substrates. Substrate competition experiments showed that cholic acid 7 alpha-dehydroxylation was reduced by increasing concentrations of chendeoxycholic acid; however, chenodeoxycholic acid 7alpha-dehydroxylation activity was unaffected by increasing concentrations of cholic acid. A 10-fold increase in cholic and 7alpha-dehydroxylation activity occurred during the transition from logarithmic to stationary phase growth whether cells were cultured in the presence or absence of sodium cholate. In the same culture, a similar increase in chenodeoxycholic acid 7alpha-dehydroxylation was detected only in cells cultured in the presence of sodium cholate. These results indicate the possible existence of two independent systems for 7alpha-dehydroxylation in C. Leptum.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				J. M. Ridlon, D.-J. Kang, and P. B. Hylemon Bile salt biotransformations by human intestinal bacteria J. Lipid Res., February 1, 2006; 47(2): 241 - 259. [Abstract] [Full Text] [PDF]

				L A Thomas, M J Veysey, G M Murphy, D Russell-Jones, G L French, J A H Wass, and R H Dowling Octreotide induced prolongation of colonic transit increases faecal anaerobic bacteria, bile acid metabolising enzymes, and serum deoxycholic acid in patients with acromegaly Gut, May 1, 2005; 54(5): 630 - 635. [Abstract] [Full Text] [PDF]

				L A Thomas, M J Veysey, G French, P B Hylemon, G M Murphy, and R H Dowling Bile acid metabolism by fresh human colonic contents: a comparison of caecal versus faecal samples Gut, December 1, 2001; 49(6): 835 - 842. [Abstract] [Full Text] [PDF]

				L. A. Thomas, M. J. Veysey, G. M. Murphy, and R. H. Dowling Influence of pH on the phase distribution of nascent deoxycholic acid in fresh human cecal aspirates Am J Physiol Gastrointest Liver Physiol, August 1, 2001; 281(2): G371 - G374. [Abstract] [Full Text] [PDF]

				H.-Q. Ye, D. H. Mallonee, J. E. Wells, I. Björkhem, and P. B. Hylemon The bile acid-inducible bai F gene from Eubacterium sp. strain VPI 12708 encodes a bile acid-coenzyme A hydrolase J. Lipid Res., January 1, 1999; 40(1): 17 - 23. [Abstract] [Full Text]

				S J Lewis and K W Heaton Increasing butyrate concentration in the distal colon by accelerating intestinal transit Gut, August 1, 1997; 41(2): 245 - 251. [Abstract] [Full Text] [PDF]