Steroid structure and function-VI. The molecular conformation of 19-hydroxy-4-androstene-3,17-dione, as an intermediate for estrogen synthetase

The molecular conformation of 19-hydroxy-4-androstene-3,17-dione has been determined crystallographically. The 19-hydroxy substituent is observed to be oriented over the A-ring, trans to the C(9)-C(10) bond. The observed bowing of the A-ring toward the α-face suggests that rotation about the C(10)-C(19) bond is hindered and that the crystallography observed conformation would prevail in the active site of the synthetase enzyme. The strain introduced by a single hydroxyl addition to the C(19) position also suggests that trihydroxylation at this position may not be feasible.