A flavoprotein (FAD) with high specificity for monoprenyl isoflavone. The product of the prenyl epoxidation reaction contains an oxygen atom derived from O2, but not from H2O. It is slowly and nonenzymically converted into the corresponding dihydrofurano derivative. The enzyme in the fungus Botrytis cinerea is induced by the substrate analogue, 6-prenylnaringenin.
