Mechanism of Biochemical Aromatization of Steroids

Estrogen biosynthesis. I. Estrogen biosynthesis. Stereospecific distribution of tritium in testosterone-1α2α-t2

“…It appears rather to indicate that the difference of polarity between the oxygen and the hydrocarbon group at C-17 influences the affinity of that end of the substrate for the catalyst, accounting for the difference in stereoselectivity. Axelrod and Goldzieher (1962) reported the C-la,C-23 removal from androgens during aromatization with normal ovaries based on 50% retention of tritium. Though the assignment of the labeling was on the basis of a wrong assumption (Morato et al, 1962), the results are not reconciled with the C-13,C-23-elimination mechanism which occurs in placental aromatization.…”

Steroidal estrogens

“…Using two samples of androst-4-ene-3,17-dione tritiated predominantly in the la and 10 positions, respectively (58), the Worcester Foundation group (290) demonstrated that when these compounds were incubated with human placental microsomes the la-H3 precursor retained most of its radioactive label whereas most of the tritium was lost when the 10-H8 compound was used as substrate. It had been reported (18) earlier that the la-hydrogen was lost during aromatization. However, it has since been pointed out (58) that this conclusion was based on incorrect assignment of configuration at the tritium containing carbon atom.…”