[Substrate specifity of "cholesteroloxidase" for the enzymatic determination of cholesterol]

The substrate specifity of "Cholesteroloxidase" (E.C.1.1.3.6) from Nocardia erythropolis was studied. The main sterols from animal and plant fats and 4-methylsterols as well as one triterpene served as substrates. The enzyme is not specific for cholesterol but also reacts with all the natural 3 beta-hydroxysterols. However, the enzymatic reaction may contribute as a new analytical method to determine the "total sterols" in the unsaponifiable matter of fats.