Separation and characterization of rat kidney isometallothioneins induced by exposure to inorganic mercury.

High-performance liquid chromatography (HPLC) was applied to the separation of metallothionein (MT) isoforms from different tissues from a variety of eukaryotic species. Recently we reported an analytical method for 203Hg-metallothionein, which detects the radioisotope bound to each iso-MT after separation by HPLC on a size-exclusion column coupled with on-line radioactivity flow detection. The MTs can be separated as distinct isoprotein peaks by elution with alkaline buffer solution owing to cation-exchange chromatographic action. In the present work, renal MT from rats exposed to inorganic mercury was separated into four peaks by UV and 203Hg detection. Moreover, it was resolved into four components by non-denaturing polyacrylamide gel electrophoresis. The two major components correspond to MT-1 and MT-2, which were characterized by amino acid analysis. Finally, Hg induces and binds to both iso-MTs.