7-Oxo-24,25-dihydrolanosterol (3 beta-hydroxy-8-lanosten-7-one, 7-oxo-HDL) was a potent competitive inhibitor for lanosterol 14 alpha-demethylase (cytochrome P-45014DM) of Saccharomyces cerevisiae. Affinity of 7-oxo-DHL for the enzyme was more than 50-times higher than those of the inherent substrates, lanosterol and 24,25-dihydrolanosterol. 7-Oxo-DHL accelerated NADPH-dependent reduction of cytochrome P-45014DM in the reconstituted system consisting of the cytochrome and NADPH-cytochrome P-450 reductase. These observations indicated that 7-oxo-DHL interacted with the substrate site of cytochrome P-45014DM. However, 7-oxo-DHL was not metabolized by the reconstituted system. Incubation of 7-oxo-DHL with the reconstituted system caused accumulation of oxyferro intermediate of cytochrome P-45014DM. It can thus be concluded that 7-oxo-DHL interfered with electron transfer to the oxyferro intermediate of the cytochrome, though it stimulated reduction of the heme iron. So far as we know, 7-oxo-DHL is the first example of a cytochrome P-450 inhibitor which selectively interferes with the electron transfer to oxyferro intermediate. 7 alpha-Hydroxy-24,25-dihydrolanosterol was also a competitive inhibitor of cytochrome P-45014DM. However, this compound was metabolized by the reconstituted system and could not block the electron transfer to oxyferro intermediate. 11-Oxo-24,25-dihydrolanosterol, an isomer of 7-oxo-DHL, did not have such inhibitory effects. These lines of evidence suggest a possibility that the keto group at C-7 of lanost-8-ene skeleton may interact with a certain site of cytochrome P-45014DM which has an important role in the electron transfer to oxyferro intermediate.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|