Enzymatic aromatization of steroids. I. Effects of oxygen and carbon monoxide on the intermediate steps of estrogen biosynthesis.

At Case Western Reserve University in Cleveland, the known intermediate steps in the aromatization, catalyxed by human placental microsomes, of 4-androstene-3, 17-dione to estrone were evaluated. Oxygen and carbon monoxide atmospheres were used to expose the properties of the participating oxidases. The results were judged to be evidence for the existence of 3 mixed function oxidases active in steroid aromatization. One of the oxidases may be a form of cytochrome P-450. The proposed microsomal components must be physically fractionated for validation of their independent existences.