title: A modified digitonin-precipitation radioassay for 3 beta-hydroxy-delta 5-steroid dehydrogenase.
abstract: An improved digitonin-precipitation radioassay for 3 beta-hydroxy-delta 5-steroid dehydrogenase is presented. It is linear for enzyme protein concentrations up to 0.6 mg and for 37 degrees C incubation times up to 10 min. Sensitivity and reproducibility are improved nine- and sevenfold, respectively, over the method of Philpott and Peron. There is a good correlation with the Philpott and Peron assay (r = 0.958) and with a thin-layer chromatography method (r = 0.997). Beyond being faster, simpler, and more sensitive than other analyses, this radioassay uses one-tenth the quantity of [3H]pregnenolone substrate and is, therefore, a safer and less expensive procedure.
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis*; D011232:Chemical Precipitation; D002855:Chromatography, Thin Layer; D004072:Digitonin; D005260:Female; D006801:Humans; D008861:Microsomes / Q000201:enzymology; D008928:Mitochondria / Q000201:enzymology; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D011284:Pregnenolone / Q000032:analysis; D011374:Progesterone / Q000032:analysis; D011375:Progesterone Reductase / Q000032:analysis*; D014316:Tritium
chemical_list: D014316:Tritium; D011374:Progesterone; D011284:Pregnenolone; D015096:3-Hydroxysteroid Dehydrogenases; D011375:Progesterone Reductase; D004072:Digitonin