title: Aromatization of testosterone and 19-nortestosterone by a single enzyme from equine testicular microsomes. Differences from human placental aromatase.
abstract: A single enzyme in the stallion testis was able to aromatize both testosterone and nortestosterone. This enzyme had a much lower affinity for nortestosterone than for testosterone. In contrast to human placental estrogen synthetase, this enzyme aromatized testosterone and 19-nortestosterone with similar efficiency. The differences observed (effects of monovalent cations, inhibition of androstenedione aromatization by testosterone and 19-nortestosterone and, above all, rate of norandrogen aromatization) suggest that the aromatase in the horse testis is not the same as that in the human placenta.
authors.affiliation: Laboratoire de Biochimie, UA CNRS 609, Caen, France.
authors.forename: P
authors.initials: P
authors.lastname: Silberzahn
authors.forename: J L
authors.initials: JL
authors.lastname: Gaillard
authors.forename: D
authors.initials: D
authors.lastname: Quincey
authors.forename: T
authors.initials: T
authors.lastname: Dintinger
authors.forename: I
authors.initials: I
authors.lastname: Al-Timimi
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D005260:Female; D006736:Horses; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000201:enzymology* / Q000378:metabolism; D009277:Nandrolone / Q000378:metabolism*; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013737:Testis / Q000201:enzymology* / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*
chemical_list: D013739:Testosterone; D009277:Nandrolone; D001141:Aromatase