Probably involved in the degradation of cholesterol. In vitro, catalyzes the introduction of a 9alpha-hydroxyl moiety into the ring B of 3-ketosteroid substrates such as 1,4-androstadiene-3,17-dione (ADD), 4-androstene-3,17-dione (AD), 4-androstene-17beta-ol-3-one (testosterone), 4-pregnene-3,20-dione (progesterone), 19-nor-4-androstene-3,17-dione (nordion), 1-(5alpha)-androstene-3,17-dione, 5alpha-androstane-3,17-dione and 5beta-androstane-3,17-dione. KSH has the highest activity with 3-keto-Delta4 steroid substrates. androsta-1,4-diene-3,17-dione + 2 H(+) + O2 + 2 reduced [2Fe-2S]-[ferredoxin] = 9alpha-hydroxyandrosta-1,4-diene-3,17-dione + H2O + 2 oxidized [2Fe-2S]-[ferredoxin] Binds 1 FAD per subunit. Binds 1 2Fe-2S cluster. KSH activity is completely inhibited by zinc ions. KshB is specifically inhibited by Cu(2+) ions. Optimum pH is 7. Optimum temperature is 33 degrees Celsius. Steroid metabolism; cholesterol degradation. The two-component system 3-ketosteroid-9-alpha-monooxygenase is composed of an oxygenase component KshA and a reductase component KshB.