Activity and inhibition of 3-beta-hydroxysteroid dehydrogenase/delta-5-4-isomerase in human skin

Article abstract of DOI:10.1159/000211481

Activity and inhibition of 3β-hydroxysteroid dehydrogenase/Δ^5-4-isomerase, a key enzyme of biosynthesis of androgenic steroids, in human skin were studied. Whole-width dermal tissue specimens excised from various regions of the male and female body were investigated with an in vitro radioenzyme assay method using dehydroepiandrosterone as substrate. The Michaelis-Menten constant of the enzyme was found to be K(m) = 10 nM and the maximal velocity was V(max) = 0.625 pmol produced 4-androstene-3,17-dione/mg protein/20 min. Activity of 3β-hydroxysteroid dehydrogenase/Δ^5-4-isomerase in male inguinal skin (n = 8) was 0.132-0.412, in female abdominal skin (n = 4) 0.140-0.255, in perineal skin (n = 4) 0.138-0.962 pmol/mg protein/20 min. The synthetic steroids cyproterone acetate, 4-MA and epostane proved to be potent inhibitors, IC₅₀ values were 150, 6.2 and 1.45 nM, respectively.