Activity and Inhibition of 3-Beta-Hydroxysteroid Dehydrogenase/Delta-5-4-lsomerase in Human Skin

Abstract

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 3 Β-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.

Determination of 17α-hydroxylase-C17,20-lyase (P45017α) enzyme activities and their inhibition by selected steroidal picolyl and picolinylidene compounds

“…the newly developed technique bears numerous advantages compared to our earlier radiosubstrate methodologies [13,[37][38]. new procedures use small volume incubates, and apply simple and efficient isolation techniques making these methods suitable for rapid and cost effective estimation of 17-hydroxylase and C 17,20 -lyase activities and their inhibition by test substances.…”

Structural analysis and biomedical potential of novel salicyloyloxy estrane derivatives synthesized by microwave irradiation

“…Inhibitory effects exerted on steroidogenic enzymes by the newly synthesized compounds 7, 10-12 and 14 were investigated with in vitro radio-labeled substrate incubations (Table 1). Our previously published methods for 3bHSD [28,34,35], 17bHSD1 [7], 17bHSD2 [27,28] and 17bHSD3 [28] were used with minor modifications. During procedures, tissue preparations serving as enzyme sources were incubated with 1 lM [ 14 C]-labeled substrate steroids in the presence of 0.1 mM coenzymes at 37°C.…”

X-ray structural analysis and antitumor activity of new salicylic acid derivatives

“…Inhibitory effects exerted on the 17bHSD2 activity by the newly synthesized compounds (1-3) were investigated via conversion of testosterone to androst-4-ene-3,17-dione in vitro. Our previously published radioincubation method for 3bHSD [30,31] was modified and adapted to the 17bHSD2 measurements. Female rat liver expresses 17bHSD2 constitutively [32], and served as feasible source of this isozyme.…”