Cytochrome P-450 was detected in microsomes and presumably in cytosol of Neurospora crassa, and was found to be inducible by progesterone. In the microsomal fraction cytochrome b5 and NADPHcytochrome c reductase activities were measurable, too. Cytochrome P-450 of Neurospora crassa is inhibited by SKF-525 A and by inhibitors of ergosterol biosynthesis. After induction of cytochrome P-450 with progesterone 1 la-hydroxyprogesterone as one metabolite of progesterone was detected in the culture media as well as in the mycelia. After 42 hours about 70% of progesterone were metabolized.
Neurosporu crussu has been studied extensively as a model object for fungal genetics and metabolism. From the analysis of wild strain and sterol biosynthesis mutant sterol patterns of Neurosporu crussu CONNERTON et ul. (1991) concluded that cytochrome (cyt.) P-450 is present in N. crussu and contributes to ergosterol biosynthesis.
ATTAR et ul. (1989) showed a cycloheximide-inducible gene of N. crussu belonging to the cyt. P-450 superfamily. LIN and WR (1979) and K A ~R and LIN (1984) demonstrated the induction of an aryl hydrocarbon hydroxylase by benzo[a]pyrene in N. crussu but did not demonstrate the presence of cyt. P-450.
In our investigation we proved the occurrence of small amounts of cyt. P-450 by carbon monoxide (CO) difference spectrum in non-treated mycelia of N. crussu and such induced by