A plant metabolic activation system from Persea americana with cytochrome P450-dependent and peroxidase activities.
Microsomal fractions from different tissues of various plants (potato, cauliflower, aubergine, avocado pear, courgette, cucumber, banana, kiwi and strawberry) were prepared and their content of cytochrome P-450 (cyt-P450) determined. A S117 fraction from Persea americana (avocado pear) presented the highest content of cyt-P450. As a consequence of these data, we have developed and characterized this fraction as a plant metabolic activation system. The P. americana S117, used in this work, contains 0.75 +/- 0.04 mg of protein per ml, 0.788 +/- 0.078 nmol of cyt-P450 per mg of protein and has a peroxidase activity of 0.036 +/- 0.005 (nmol tetraguaiacol/micrograms protein/min). The P. americana cyt-P450 remained stable during at least 60 days, stored at -80 degrees C. This fraction activated 2-aminofluorene to a mutagenic product in S. typhimurium TA98, while it had no effect on the benzo[a]pyrene activation. The treatment of the P. americana S117 with CO, the addition of diethyldithiocarbamate (DETC) or the absence of a NADPH-generating system in the activation mix, produced a partial inhibition of the 2-aminofluorene activation. Both peroxidase activity and a cyt-P450-dependent activity are assumed to be involved in the activation of this chemical mediated by P. americana S117.
Chiapella
C
C
Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Spain.
Ysern
P
P
Riera
J
J
Llagostera
M
M
D001564:Benzo(a)pyrene / Q000378:metabolism / Q000633:toxicity; D001711:Biotransformation; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005449:Fluorenes / Q000378:metabolism / Q000633:toxicity; D005638:Fruit / Q000201:enzymology*; D008861:Microsomes / Q000201:enzymology; D009152:Mutagenicity Tests; D009153:Mutagens / Q000378:metabolism / Q000633:toxicity; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D014675:Vegetables / Q000201:enzymology; D003313:Zea mays / Q000201:enzymology
D005449:Fluorenes; D009153:Mutagens; D010940:Plant Proteins; D001564:Benzo(a)pyrene; C012177:2-aminofluorene; D003577:Cytochrome P-450 Enzyme System; D010544:Peroxidases