PURIFICATION AND CHARACTERIZATION OF METALLOTHIONEIN FROM SYNECHOCOCCUS CEDRORUM

The metallothionein (MT) is induced from synechococcus cedrorum growing in medium added gradually with cadmium chloride,and purified and characterized by means of Sephadex G-50. DEAE-cellulose (DE-52) and Sephadex G-25 colunm chromatography. The results show MT has no isoforms and is demonstrated to be homogenous by SDS-PAGE. Each molecule of MT contains 10 mercapto groups and combines with 5 cadmium atoms. Its molechlar weight is about 7.6KD,with isoelectric point being about pH4.5.Its cysteine resides account for 15.5% of all amino acid resides. The MT with a characteristic absorption maxium at 250nm is poorly stable with a large decrease of the absorption peak in low pH, and contains a little aromatic acid.