Isolation and structural characterization of hepatic metallothionein from the roach (Rutilus rutilus L.)

Metallothioneins (MTs), considered as metal biomarkers by many authors, are very conserved proteins that present great interests in phylogenetical stu dies. This paper reports the purification of the hepatic MT from the roach (Rutilus rutilus). After extensive reverse-phase HPLC, the sequence of the MT was established by a combination of techniques including automated Edman degradation, mass spectrometry and enzymatic treatment. Sequence compariso n with other fishes or mammalian MTs showed considerable identities and a h igh conservation in cysteine residues positions. MTs of roach and goldfish that both belong to the same family (Cyprinidae) share 97% identity. Ninety five% identity were found between roach and stone leach (Cypriniforms, Cob itidae) MTs. Only 77% identity were found with pleuronectiforms or salmonif orms. This sequence brings a new element in the study of the phylogenetical relationships among teleost species.