| Abstrakt: |
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 K1of 1.4 uM and 8.5 uM, respectively, towards androstenedione aromatization. 3,5,3′-Triiodothyronine with a K1of 1.8 uM 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. |
