Characterization of Brain and Liver Aromatase of Gilthead Seabream (Sparus aurata L., 1758) using Dibenzylfluorescein

Aromatase catalyzes the conversion of androgens into estrogens. data on native aromatase enzyme kinetics and thus actual catalytic activity are scarce in fish, impeding comparison of aromatase activity (aa) from different organs within and between species. in the present study, fluorescence aromatase assay was optimized to measure aa in the gilthead seabream (sparus aurata l., 1758) using dibenzylfluorescein (dbf) as a fluorometric substrate in brain and liver microsomes. brain and liver aa have showed linearity until 20 and 40 μg protein concentration throughout 30 minutes, respectively. in brain and liver optimum ph of the enzyme was found to be 6.50 and 8.25, respectively and optimum temperature was found to be 30°c for both tissues. it has been observed that brain and liver aa have saturated at and above 2 μm dbf concentrations. determined vmax and km values of brain and liver aromatase using lineweaver-burk graph have calculated 8,054±0,550 and 8,389±0,543 pmol/min/mg protein and 0,840±0,161 μm and 0,959±0,152 μm, respectively. testosterone appeared to competitively inhibit the sparus aurata brain and liver aromatase. in conclusion, the parameters of this assay that are reported for brain and liver aromatase in gilthead seabream could be useful to measure aa in other species.