Characterization of cytochrome P450 dependent mixed-function oxidase system of gilthead seabream ( sparus aurata; sparidae) liver

Abstract

1. 1. The average cytochrome P450 content of gilthead seabeam liver microsomes was found to be 0.078 ± 0.012 ( n = 4) nmol/mg protein, which was about 50%, 24% and 13% of that measured in trout, sturgeon and scup liver microsomes, respectively. 2. 2. Gilthead seabream liver microsomes contained a relatively higher amount of cytochrome b5, as 0.32 ± 0.05 ( n = 4) nmol/mg protein. 3. 3. Effects of microsomal protein amount and temperature ranging from 15 to 30°C on aniline 4-hydroxylation and ethylmorphine N-demethylation activities were examined. No significant differences were observed between the enzyme activities at these temperatures. 4. 4. The liver microsomal aniline 4-hydroxylase activity of gilthead seabream in the 1990 fall (0.016–0.021 nmol p-aminophenol/min/mg protein) was 4.5–6 times higher than that in the 1991 spring (0.003–0.004 nmol p-aminophenol/min/mg protein). 5. 5. Liver microsomal ethylmorphine N-demethylase activity measured in 1991 spring (0/371) nm ol formaldehyde/min/mig protein) was 41% higher than that in 1990 fall (0.263 nmol formaldehyde/min/mg protein).