Biosynthesis of Estrogens: Aromatization of (19R)-, (19S)-, and (19RS)--3β-Hydroxyandrost-5-en-17-ones by Human Placental Aromatase

Article abstract of DOI:10.1021/ja00268a023

It is shown, with the use of (19R)- and (19S)-<19-3H,2H,1H>-3β-hydroxyandrost-5-en-17-ones, that the "first" C-19 hydroxylation by human placental aromatase involves a normal kinetic isotope effect k_H > k_D >k_T.The hydroxylation proceeds stereospecifically in the retention mode; i.e., the incoming hydroxyl assumes the orientation of the displaced (isotopic) hydrogen atom.