Genetically engineered V79 Chinese hamster cell expression of purified cytochrome P-450IIB1 monooxygenase activity.
Chinese hamster V79 fibroblasts, frequently used as target cells in short-term tests for mutagenicity, do not possess measurable monooxygenase activity; in particular, enzymatic oxidation of testosterone (T) cannot be demonstrated. If these V79 cells, however, had been transfected with the cDNA-encoding rat liver cytochrome P-450IIB1 under control of the SV40 early promoter, they stably expressed monooxygenase activity. These so-called SD1 cells then oxidatively metabolized T at a rate of 27 pmol/mg protein/min, converting it to 16 alpha- and 16 beta-hydroxy-T as well as 4-androsten-3,17-dione as sole metabolites in a ratio of 1.1:1.0:1.6. The regio- and stereoselective conversion of T by SD1 cells, as well as the quantitative distribution of the metabolites, corresponds well with the results reported for pure cytochrome P-450IIB1 in a reconstituted system.
Platt
K L
KL
Institute of Toxicology, University of Mainz, Federal Republic of Germany.
Molitor
E
E
Döhmer
J
J
Dogra
S
S
Oesch
F
F
D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003412:Cricetulus; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D005818:Genetic Engineering; D007527:Isoenzymes; D007664:Ketosteroids / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000378:metabolism; D014162:Transfection
D007527:Isoenzymes; D007664:Ketosteroids; D013739:Testosterone; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D010634:Phenobarbital