Interaction of azole antifungal agents with cytochrome P-45014DM purified from Saccharomyces cerevisiae microsomes

doi:10.1016/0006-2952(87)90694-0

Biochemical Pharmacology

Volume 36, Issue 2, 15 January 1987, Pages 229-235

https://doi.org/10.1016/0006-2952(87)90694-0 Get rights and content

Abstract

Mechanism of action of azole antifungal agents was studied by analyzing interaction of ketoconazole, itraconazole, triadimefon and triadimenol with a purified yeast cytochrome P-450 which catalyzes lanosterol 14α-demethylation (P-450_14DM). These antifungal agents formed low-spin complexes with P-450_14DM, indicating the interaction of their azole nitrogens with the heme iron. Affinity of these antifungal agents for the cytochrome was extremely high compared with usual nitrogenous ligands. Upon reduction with sodium dithionite, the azole complexes of ferric P-450_14DM were converted to the corresponding ferrous derivatives. Spectral analysis of these complexes suggested that geometric orientation of the azole moiety of an antifungal agent to the ferrous heme iron was regulated by the interaction between the N-1 substituent and the heme environment. CO could not readily replace ketoconazole or itraconazole co-ordinating to the heme iron of ferrous P-450_14DM while triadimefon and triadimenol complexes of the cytochrome were promptly converted to the CO complexes. The inhibitory effects of ketoconazole and itraconazole on the P-450_14DM-dependent lanosterol 14α-demethylation were higher than that of triadimenfon. The substituents at N-1 of the azole moieties of ketoconazole and itraconazole are extremely large while those of triadimefon and triadimenol are relatively small. Accordingly, observations described above suggest that the N-1 substituent of an azole antifungal agent regulates the mobility of the molecule in the heme crevice of ferrous P-450_14DM and determines the inhibitory effect of the compound.

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Interaction of azole antifungal agents with cytochrome P-45014DM purified from Saccharomyces cerevisiae microsomes

Abstract

Pest. Biochem. Physiol.

Biochem. biophys. Res. Commun.

Biochem. biophys. Res. Commun.

Biochim. biophys. Acta

J. biol. Chem.

Biochem. biophys. Res. Commun.

J. biol. Chem.

Archs Biochem. Biophys.

J. biol. Chem.

J. biol. Chem.

Interaction of azole antifungal agents with cytochrome P-450_14DM purified from Saccharomyces cerevisiae microsomes