THE CONVERSION OF PROGESTERONE TO Δ4 PREGNENE-20α-OL, 3-ONE BY HUMAN PLACENTA IN VITRO

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Abstract
The conversion of progesterone to [DELTA]4 pregnene-20[alpha]-OL, 3-one by the non-particulate fraction of human placenta and triphosphopyridine nucleotide is described. Fresh human placentas were obtained at term from pelvic delivery or hysterotomy from normal patients. The tissue was ground for 30 seconds in a Waring blendor at full speed at 4[degree]C in a solution of 0.25 [image] sucrose, 0.1 [image] phosphate buffer pH 6.0, and 0.04 [image] nicotinamide. The enzyme mediating the reaction requires reduced triphosphopyridine nucleotide as a cofactor, has a pH optimum at 6.2, is precipitated by 20 to 30% saturated ammonium sulfate, and is relatively stable when stored at -15[degree]C. This enzyme is present in human fetal liver and hydatidiform mole, but not in human myometrium or choriocarcinoma. It has been demonstrated in placental tissue ranging in age from 12 weeks to term, but not in one 6 weeks old. It is also present in cow placenta.