title: 17 beta-Hydroxysteroid oxidoreductase activity in human maternal and umbilical cord sera.
abstract: The specific activity of 17 beta-hydroxysteroid oxidoreductase (17 beta-HSOR) in human umbilical cord arterial serum has been reported to be similar to that of maternal serum and 5- to 15-times higher than that of cord venous serum. Based on these findings, it was proposed that 17 beta-HSOR in cord arterial serum arises from fetal tissue sources other than placenta. In the course of studies of the role of 17 beta-HSOR in the modulation of bioactive estrogen levels in the human fetus, we determined that: (i) the specific activity of 17 beta-HSOR in maternal serum is 2.1- to 55-times higher than that in either umbilical cord venous serum or cord arterial serum; (ii) the specific activity of 17 beta-HSOR in umbilical cord venous and cord arterial sera are similar; (iii) anti-human placental cytosolic 17 beta-HSOR antibody inactivates the 17 beta-HSOR in maternal, umbilical cord arterial, and cord venous sera but not in maternal or fetal erythrocytes; (iv) the specific activity of 17 beta-HSOR in maternal serum (expressed per mg protein) is higher than that in umbilical cord serum and maternal and fetal erythrocytes, and is approximately 700-times lower than that of the placental microsomal enzyme; (v) the preferred cofactor for maternal serum 17 beta-HSOR is NADP+; (vi) 17 beta-HSOR is associated with the high speed supernatant fraction of maternal serum rather than with the particulate fraction; and, (vii) the patterns of binding of [3H]estradiol-17 beta to proteins in maternal and umbilical cord arterial sera and those of 17 beta-HSOR activity, determined in corresponding fractions obtained after sucrose density gradient centrifugation, are approximately coincidental at S20, omega 4.6-5. The findings of higher 17 beta-HSOR levels in maternal serum compared with umbilical cord arterial serum and the inactivation of the cord arterial serum enzyme by an antibody that recognizes human placental cytosolic 17 beta-HSOR is suggestive that 17 beta-HSOR in cord arterial serum is of placental origin.
authors.affiliation: Cecil H. and Ida Green Center for Biology Sciences, University of Texas Southwestern Medical Center, Dallas 75235.
authors.forename: L
authors.initials: L
authors.lastname: Milewich
authors.forename: S J
authors.initials: SJ
authors.lastname: Fortunato
authors.forename: M
authors.initials: M
authors.lastname: Barris
authors.forename: M C
authors.initials: MC
authors.lastname: Maberry
authors.forename: L C
authors.initials: LC
authors.lastname: Gilstrap
authors.forename: P C
authors.initials: PC
authors.lastname: MacDonald
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000097:blood* / Q000276:immunology; D000906:Antibodies / Q000494:pharmacology; D002725:Chloroform; D004912:Erythrocytes / Q000201:enzymology; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005312:Fetal Blood / Q000201:enzymology*; D005615:Freezing; D005990:Glycerol; D006801:Humans; D007700:Kinetics; D009249:NADP / Q000032:analysis; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D014316:Tritium; D014469:Umbilical Arteries; D014471:Umbilical Veins
chemical_list: D000906:Antibodies; D014316:Tritium; D004958:Estradiol; D009249:NADP; D002725:Chloroform; D015067:17-Hydroxysteroid Dehydrogenases; C032690:3-alpha-(17-beta)-hydroxysteroid dehydrogenase (NAD(+)); D005990:Glycerol