title: Inhibition of human placental microsomal aromatase by thyroid hormone and iodothyronine derivatives.
abstract: The initial velocity kinetics of the effect of thyroid hormone and analogs on human placental microsomal aromatase were studied. Thyroxine and its propionic analog 3,5,3',5'-tetraiodothyropropionic acid show a competitive inhibition with an apparent Ki of 1.4 microM and 8.5 microM, respectively, towards androstenedione aromatization. 3,5,3'-Triiodothyronine with a Ki of 1.8 microM shows a decreased affinity compared to thyroxine. Two analogs, 3,5,3'-triiodothyropropionic acid and 3,5,3'-triiodothyroacetic acid appear to have negligible competition.
authors.affiliation: Endocrine Biochemistry Department, Medical Foundation of Buffalo, Inc., NY 14203.
authors.forename: K
authors.initials: K
authors.lastname: Bullion
authors.forename: Y
authors.initials: Y
authors.lastname: Osawa
mesh_terms: D047072:Aromatase Inhibitors; D001667:Binding, Competitive; D005260:Female; D006801:Humans; D008861:Microsomes / Q000201:enzymology*; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013974:Thyroxine / Q000031:analogs & derivatives / Q000494:pharmacology*; D014284:Triiodothyronine / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: D047072:Aromatase Inhibitors; D014284:Triiodothyronine; D013974:Thyroxine