Abstract: In order to study the sub-isoforms of MTand get their exact primary structure, the mixture and the individuals MT-1 and MT-2 of rabbit liver MTwere separated by different HPLCmethods such as anion exchange and RP-HPLCunder different conditions. The two main MTisoforms MT-1 and MT-2 could be easily isolated from the mixture of MTby anion exchange HPLC. The isoforms of MTs were further isolated by C₁₈ RP-HPLCunder neutral and acidic conditions. All of the isolated isoforms and sub-isoforms were analyzed by MALDI-TOF-MS. The separation of MTisoforms can be obtained by anion exchange chromatography with 50 mmol/L Na₂HPO₄ NaCl. The sub-isoforms of rabbit liver MTcould be isolated by C₁₈ RP-HPLC. The rabbit liver MT-1 has 3 main sub-isoforms and MT-2 has one sub-isoform. The experiment verified that under different conditions the sub-isoforms of rabbit liver MThas a different apparent molecular mass. This experiment predicted that there would exist a stable peptide structure of MT-2 or its fragment. The primary structure of this peptide component was also studied.

Key words: Metallothionein, Sub isoform, RP-HPLC, ESI-MS, MALDI-TOF-MS