Characterization of a Corticosteroid 21-dehydroxylase From the Intestinal Anaerobic Bacterium, Eubacterium Lentum

J Lipid Res. 1980 Jul;21(5):585-93.


An oxygen-sensitive corticosteroid 21-dehydroxylase has been characterized in cell extracts of Eubacterium lentum. The enzyme was highly specific for corticosteroids containing and alpha-ketol structure and required FMNH2 or reduced benzyl viologen for activity. The enzyme used deoxycorticosterone, deoxycortisol, dehydrocorticosterone, and corticosterone as substrates. Substrate saturation kinetics using [3H]corticosterone yielded an apparent Km of 7.35 microM and a Vmax of 15.4 nmol (11 beta-[3H]hydroxyprogesterone) formed per hr x mg protein-1. 21-Dehydroxylase activity was inhibited by both water-soluble and lipophilic metal ion chelators. NADH: flavin oxidoreductase and 21-dehydroxylase activities were separated by anaerobic DEAE-cellulose and Sepharose 6B chromatography. 21-Dehydroxylase had a relative weight of 582,000 as determined by Sepharose 6B chromatography. There was a 7-fold increase in the rate of 21-dehydroxylation of [3H]deoxycorticosterone in whole cell suspensions of E. lentum sparged with H2 as compared to argon gas.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anaerobiosis
  • Eubacterium / enzymology*
  • Eubacterium / growth & development
  • Humans
  • Intestines / microbiology
  • Kinetics
  • Steroid 21-Hydroxylase / isolation & purification
  • Steroid 21-Hydroxylase / metabolism*
  • Steroid Hydroxylases / metabolism*
  • Substrate Specificity


  • Steroid Hydroxylases
  • Steroid 21-Hydroxylase