Studies on 17 beta-hydroxysteroid dehydrogenase in human endometrium and endometrial carcinoma. III. Partial purification and characterization of the microsomal enzyme

Microsomal 17 beta-hydroxysteroid dehydrogenase obtained from the human secretory endometrium (17 beta-HSD) was solubilized with triton X-100. A 4-fold purification was achieved by ammonium sulphate precipitation and isoelectric focusing. In the presence of glycerol the partially purified enzyme was...

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Bibliographic Details
Published inActa endocrinologica (Copenhagen) Vol. 80; no. 2; p. 355
Main Authors Pollow, K, Lübbert, H, Pollow, B
Format Journal Article
LanguageEnglish
Published Denmark 01.10.1975
Subjects
Androstenedione
Endometrium - enzymology
Estradiol - metabolism
Estrone - metabolism
Female
Humans
Hydroxysteroid Dehydrogenases - isolation & purification
Hydroxysteroid Dehydrogenases - metabolism
Microsomes - enzymology
NAD - pharmacology
NADP - pharmacology
Testosterone - metabolism
Uterine Neoplasms - enzymology
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Summary:Microsomal 17 beta-hydroxysteroid dehydrogenase obtained from the human secretory endometrium (17 beta-HSD) was solubilized with triton X-100. A 4-fold purification was achieved by ammonium sulphate precipitation and isoelectric focusing. In the presence of glycerol the partially purified enzyme was stable at 4 degrees C for at least 48 h. Using crude microsomes, the conversion of oestradiol to oestrone was linear with time and with the concentration of protein. The optimum temperature was approximately 40 degrees C and the optimum pH 9.4. For the reduction of oestrone the optimum pH was 6.5. With NAD, oestradiol was oxidized approximately three times more rapidly than with NADP. Km-values for oestradiol were nearly the same in endometrial carcinoma and in proliferative and secretory endometrium (i.e. approximately 3 X 10(-6) M). The maximal velocity was highest in secretory endometrium. Testosterone and androstenedione could also serve as substrates but they were interconverted more slowly than oestradiol and oestrone. Sulphhydryl groups were shown to be essential for catalysis.
ISSN:0001-5598