Isolation and characterization of naturally and artificially induced hepatic metallothioneins from two species of flatfish: Limanda limanda and Microstomus kitt

The separation of hepatic metallothioneins of Limanda limanda and Microstomus kitt by gel-filtration chromatography, anion-exchange high-performance liquid chromatography (HPLC) and reversed-phase HPLC is described. Two isoforms of metal-binding proteins were isolated by DEAE HPLC chromatography from fish caught in the field and fish injected intraperitoneally with Cd. The amino acid composition of these proteins further purified by reversed-phase HPLC chromatography revealed the existence of metallothioneins. The route of contamination (natural or artificial) of the fish has no effect on the nature of these proteins and one of the two protein isoforms from each species has similar ionic properties.