FLUCYTOSINE IS TAKEN UP BY FUNGAL ORGANISMS VIA THE ENZYME CYTOSINE PERMEASE. INSIDE THE FUNGAL CELL, FLUCYTOSINE IS RAPIDLY CONVERTED TO FLUOROURACIL BY THE ENZYME CYTOSINE DEAMINASE. FLUOROURACIL EXERTS ITS ANTIFUNGAL ACTIVITY THROUGH THE SUBSEQUENT CONVERSION INTO SEVERAL ACTIVE METABOLITES, WHICH INHIBIT PROTEIN SYNTHESIS BY BEING FALSELY INCORPORATED INTO FUNGAL RNA OR INTERFERE WITH THE BIOSYNTHESIS OF FUNGAL DNA THROUGH THE INHIBITION OF THE ENZYME THYMIDYLATE SYNTHETASE.