Interaction of azole antifungal antibiotics with cytochrome P-450-dependent 14 alpha-sterol demethylase purified from Candida albicans.
The interaction of azole antifungal antibiotics with purified Candida albicans cytochrome P-450-dependent 14 alpha-sterol demethylase (P-450DM) was measured spectrophotometrically and by inhibition of enzyme activity. Ketoconazole and ICI 153066 (a triazole derivative) formed low-spin complexes with the ferric cytochrome and induced type II difference spectra. These spectra are indicative of an interaction between the azole moiety and the sixth co-ordination position of P-450DM haem. Both azoles inhibited the binding of CO to the sodium dithionite-reduced ferrous cytochrome, and inhibited reconstituted P-450DM activity by binding to the cytochrome with a one-to-one stoichiometry. Similarly, total inhibition of enzyme activity occurred when equimolar amounts of clotrimazole, miconazole or fluconazole were added to reconstituted P-450DM. These results correlated with the inhibition of P-450DM in broken cell preparations, confirming that all five azoles are potent inhibitors of ergosterol biosynthesis in C. albicans.
Hitchcock
C A
CA
Department of Microbiology, University of Leeds, U.K.
Dickinson
K
K
Brown
S B
SB
Evans
E G
EG
Adams
D J
DJ
D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D002176:Candida albicans / Q000201:enzymology*; D002248:Carbon Monoxide / Q000378:metabolism; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification; D005290:Ferric Compounds; D007654:Ketoconazole / Q000494:pharmacology; D008798:Mevalonic Acid / Q000378:metabolism; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D013057:Spectrum Analysis; D058886:Sterol 14-Demethylase; D014230:Triazoles / Q000494:pharmacology
D000935:Antifungal Agents; D001393:Azoles; D065607:Cytochrome P-450 Enzyme Inhibitors; D005290:Ferric Compounds; D014230:Triazoles; C040032:ICI 153066; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D058886:Sterol 14-Demethylase; D007654:Ketoconazole; D008798:Mevalonic Acid