Catalysis of the reaction: cholest-4-en-3-one + NADH + H+ + O2 = 26-hydroxycholest-4-en-3-one + NAD+ + H2O. This reaction involves the hydroxylation of the C26 carbon, followed by oxidation of the alcohol to the carboxylic acid via the aldehyde intermediate.
cholest-4-en-3-one 26-monooxygenase activity