. "Catalysis of the reaction: 17-alpha-hydroxyprogesterone = acetaldehyde + 4-androstene-3,17-dione." . . "17-alpha-hydroxyprogesterone aldolase activity" . "17-alpha-hydroxyprogesterone acetaldehyde-lyase activity" . "17alpha-hydroxyprogesterone acetaldehyde-lyase (4-androstene-3,17-dione-forming)" . "17alpha-hydroxyprogesterone acetaldehyde-lyase activity" . "17alpha-hydroxyprogesterone aldolase activity" . "C-17/C-20 lyase activity" . .