Estrogen Biosynthesis. III. Stereospecificity of Aromatization by Normal and Diseased Human Ovaries1

Minces of cystic, polycystic, precocious pubertal and normal human ovaries were incubated with lα,2α-3H-4-14C-testosterone (43%, lα; 7%, 1β; 43%, 2α; and 6%, 2β). After isolation and purification of 17β-estradiol using paper chromatography, countercurrent distribution and reverse isotope dilution, the stereospecificity of the hydrogen removal from the C-l and C-2 positions during aromatization was deduced from the change in the 3H/14C ratio. 17β-Estradiol formed by various ovarian minces retained 85–90% of the original tritium. Formation of 2,4-dibromo-17β-estradiol reduced the 3H/14C ratio by 48–52%. These results show that all the ovarian minces studied removed the cis-1β,2β-hydrogens from testosterone during aromatization. This mechanism is different from those previously reported for human ovaries but the same as that determined for human placental aromatization.