Gel and anion exchange chromatographic properties of copper-containing metallothioneins

Chromatographic properties of copper-binding proteins (copper-containing metallothioneins) induced in rat liver and kidney by the injection of either copper in the liver and kidney or cadmium in the kidney were compared with those of metallothioneins, with low or no copper content, induced by the injection of cadmium or zinc in the liver both on a Sephadex G-75 column and on a DEAE Sephadex A-25 column. The copper-containing metallothioneins were eluted at a slightly slower rate on a Sephadex G-75 column and at a higher buffer concentration on an anion exchange column than the metallothioneins with low or no copper content regardless of the inducing metals, copper or cadmium. The different chromatographic properties of the metallothioneins with high and low copper contents may be explained by the more compact conformation of the proteins with high copper contents than those with low or no copper contents and by the changes of electrostatic charge with coordination by copper.