The inducible and cytochrome P450-containing dehydroepiandrosterone 7alpha-hydroxylating enzyme system of Fusarium moniliforme.
7Alpha-hydroxylation of DHEA by Fusarium moniliforme was investigated with regard to inducibility and characterization of the responsible enzyme system. Using GC/MS, the 7-hydroxylated metabolites of DHEA produced after biotransformation by Fusarium moniliforme mycelia were identified. The strain of Fusarium moniliforme hydroxylated DHEA predominantly at the 7alpha-position, with minor hydroxylation occurring at the 7beta-position. Constitutive 7alpha-hydroxylation activity was low, but DHEA induced the enzyme complex responsible for 7alpha-hydroxylation via an increase in protein synthesis. DHEA 7alpha-hydroxylase was found to be mainly microsomal, and the best production yields of 7alpha-hydroxy-DHEA (28.5 +/- 3.51 pmol/min/mg protein) were obtained with microsomes prepared from 18-h-induced mycelia. Kinetic parameters (KM=1.18 +/- 0.035 microM and Vmax=909 +/- 27 pmol/min/mg protein) were determined. Carbon monoxide inhibited 7alpha-hydroxylation of DHEA by microsomes of Fusarium moniliforme. Also, exposure of mycelia to DHEA increased microsomal P450 content. These results demonstrated that: (i) DHEA is 7alpha-hydroxylated by microsomes of Fusarium moniliforme; (ii) DHEA induces Fusarium moniliforme 7alpha-hydroxylase; (iii) this enzyme complex contains a cytochrome P450.
Cotillon
A C
AC
Laboratoire de Biotechnologie, Conservatoire National des Arts et Métiers, Paris, France.
Doostzadeh
J
J
Morfin
R
R
D002248:Carbon Monoxide / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives / Q000378:metabolism*; D004790:Enzyme Induction; D005670:Fusarium / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006900:Hydroxylation; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D013250:Steroid Hydroxylases / Q000096:biosynthesis / Q000378:metabolism*
D003687:Dehydroepiandrosterone; C003587:7-hydroxydehydroepiandrosterone; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; C115867:oxysterol 7-alpha-hydroxylase