Isolation of Cd-binding protein of water hyacinth (Eichhornia crassipes) grown in Nile river water

Abstract

Many investigators have reported that water hyacinth plants can accumulate toxic heavy metal ions and may be useful for elutriation of polluted water. The purpose of our study was to search for the mechanism by which these plants tolerate and accumulate toxic metal ions. Cadmium was accumulated in the plants against the concentration gradient, mostly as a soluble form in the cytoplasm. Isolation and Purification of Cd-binding protein with sephadex A-25 and fractionation on sephadex G-100 showed that the accumulated Cd was associated with two major protein fractions.The first with molecular weight 25 - 20 kD contained about 35% of bound Cd. The second fraction with molecular weight 12 - 8 kD contained about 40% of bound Cd. The two forms were found also in water hyacinth cultivated in Nile water as a control, although the amount of Cd accumulated was less than those exposed to excess Cd.