title: [Microsome-associated 17 beta-hydroxysteroid dehydrogenases of human placenta, i solubilization, enrichment and separation of two 17 beta-hsd-activities after phospholipase-Treatment].
abstract: Treatment of human placenta microsomes with phospholipase A or D inhibits the 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity, parallel with the hydrolysis of membrane phospholipids. The 17beta-HSD activity of phospholipase treated microsomes is reactivated by synthetic phospholipids. The distribution of 17beta-HSD activity in subfractions of original microsomes and of phospholipase treated microsomes obtained by zonal centrifugation was studied. Solubilization of the microsomal 17beta-HSD was achieved by phospholipase A treatment. Two 17beta-HSD were solubilized from human placenta microsomes by phospholipase A treatment and were further purified by ammonium sulphate precipitation, gel filtration on BioGel A-0.5 m, DEAE-Sephadex chromatography and by isoelectric focusing. The enzymes were purified 25.8 and 17.4 times. The isoelectric points and molecular weights of the two 17beta-HSD were determined. Both enzymes are of a 17beta-HSD type. One of the 17beta-HSD, however, was sensitive to estradiol-17beta, the other to testosterone. The question of whether the two enzymes constitute a monomer and a dimer of the same 17beta-HSD or are completely different enzymes, is discussed.
mesh_terms: D002501:Centrifugation, Zonal; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003720:Densitometry; D004721:Endoplasmic Reticulum; D006801:Humans; D006913:Hydroxysteroid Dehydrogenases / Q000302:isolation & purification / Q000378:metabolism*; D007525:Isoelectric Focusing; D008861:Microsomes / Q000201:enzymology; D008970:Molecular Weight; D010740:Phospholipases / Q000008:administration & dosage*; D010920:Placenta / Q000201:enzymology / Q000502:physiology; D012995:Solubility
chemical_list: D006913:Hydroxysteroid Dehydrogenases; D010740:Phospholipases
vernacular_title: 17 BETA-Hydroxysteroid-Dehydrogenasen aus Humanplacenta-Mikrosomen, I Solubilisierung, Anreicherung und Separierung zweier 17beta-HSD-Aktivitäten nach Phospholipase-Behandlung