C. Chiapella et al., A PLANT METABOLIC-ACTIVATION SYSTEM FROM PERSEA-AMERICANA WITH CYTOCHROME P450-DEPENDENT AND PEROXIDASE-ACTIVITIES, Mutation research, 329(1), 1995, pp. 11-18
Microsomal fractions from different tissues of various plants (potato,
cauliflower, aubergine, avocado pear, courgette, cucumber, banana, ki
wi 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 pla
nt metabolic activation system. The P. americana S117, used in this wo
rk, 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/mu g protein/min). The P. americana cyt-P
450 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 activat
ion. The treatment of the P. americana S117 with CO, the addition of d
iethyldithiocarbamate (DETC) or the absence of a NADPH-generating syst
em in the activation mix, produced a partial inhibition of the 2-amino
fluorene activation. Both peroxidase activity and a cyt-P450-dependent
activity are assumed to be involved in the activation of this chemica
l mediated by P. americana S117.