Cadmium-binding proteins induced in the earthworm.

Earthworms, Eisenia foetida, grown in composts of different cadmium concentrations accumulated cadmium in a dose-dependent manner and the cadmium was bound to three different molecular weight cadmium-binding proteins induced in the earthworm. The three proteins were stable to heat treatment and accompanied by a concomitant increase of absorbance at 254 nm and not at 280 nm. Each of the three proteins is a mixture of isoproteins; the molecular weight of one of the three proteins was estimated to be about 7,000 daltons, on the assumption that the cadmium-binding protein is similar in chromatographic properties to metallothionein.