Characterization of a corticosteroid 21-dehydroxylase from the intestinal anaerobic bacterium, Eubacterium lentum.

• Main Authors: S D Feighner, P B Hylemon
• Format: Article
• Language: English
• Published: Elsevier 1980-07-01
• Series: Journal of Lipid Research
• Online Access: http://www.sciencedirect.com/science/article/pii/S002222752042228X

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.