title: 16 alpha-dehydration of corticoids by bacteria isolated from rat fecal flora.
abstract: Two strains (No. 144 and No. 146) of rat intestinal anaerobic bacteria, phenotypically similar to Eubacterium lentum, were isolated and found capable of 16 alpha-dehydrating corticoids. The initial step in the 16 alpha-dehydration of 16 alpha-hydroxyprogesterone was dehydration at the C-16 and C-17 position with the accumulation of 16-dehydroprogesterone. This step required the side chain at C-17. In bacterial cultures the 16-dehydroprogesterone was then slowly reduced to iso-progesterone. 16 alpha-Hydroxypregnanolone was also converted to iso-pregnanolone by these bacteria. 16 alpha-Dehydratase was easily demonstrated in cell fractions of strain No. 144 incubated either aerobically or anaerobically. The same extracts did not convert 16-dehydroprogesterone to iso-progesterone under similar assay conditions. 16 alpha-Dehydration occurred at all substrate concentrations tested (20 to 200 micrograms/ml) provided the pH of the growth medium was between 6 abd 8 and the Eh below -130 mV. Strain No. 146 had both 16 alpha-dehydration and 21-dehydroxylation activities. The two enzymes functioned independently. A role for intestinal bacteria in the biotransformation of biliary 16 alpha-hydroxylated steroids and subsequent excretion in the urine is proposed.
mesh_terms: D000305:Adrenal Cortex Hormones / Q000378:metabolism*; D000818:Animals; D001419:Bacteria / Q000302:isolation & purification / Q000378:metabolism*; D003900:Desoxycorticosterone / Q000378:metabolism; D005051:Eubacterium / Q000378:metabolism; D005243:Feces / Q000382:microbiology*; D006836:Hydro-Lyases / Q000378:metabolism*; D007700:Kinetics; D051381:Rats; D013379:Substrate Specificity
chemical_list: D000305:Adrenal Cortex Hormones; D003900:Desoxycorticosterone; C034412:16 alpha-hydroxyprogesterone dehydratase; D006836:Hydro-Lyases