7a-Dehydroxylase

Graph 8.10 7a-dehydroxylase activity in stone-free controls and patients with cholesterol GBS. Data taken from references 40 and 41. 

Both 7a//S-dehydroxylase and A -steroid reductase activities are stimulated by adding NAD to anaerobically dialyzed cell extracts of Eubacterium sp. V.P.I. 12708. NADH inhibited all 3 activities at high concentrations (0.5 mM) but stimulated 7a-dehydroxylase activity at lower concentrations (< 0.10 mM). Double reciprocal plots of NADH inhibition of 7a-dehydroxylase activity suggested negative cooper-ativity. The effect of low concentrations of NADH on the kinetics of 7/8-dehydroxyl-ase and A -steroid reductase activity is presently unknown. The activity of 7a-dehy-... 

Dietary fat has been implicated as a risk factor for colon cancer, possibly due to the enhanced levels of bile acids that are released. Bacterial 7a-dehydroxylase acts on primary bile acids to release secondary bile acids, which have a cytotoxic effect on the... 

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