Evidence for the natural occurance of (cadmium, copper)-metallothionein in the crab Cancer pagurus

Abstract

1. The presence of high cadmium in crabs, Cancer pagurus, from Orkney and Shetland has been confirmed. The mean value for cadmium in these crabs is about 3 times higher than those from Devon and Aberdeen, but the peak values are about 5 times higher. 2. A low molecular weight, heat-stable, cadmium and copper binding protein having the characteristics of metallothionein has been isolated from the hepatopancreas of wild specimens of the crab, Cancer pagurus. 3. Induction of metallothionein was achieved both by feeding with cadmium treated mussels and by injection. 4. The major product isolated showed a pair of bands on gel electrophoresis. They were designated metallothionein II-A and II-B and had apparent molecular weights of approx 10,000-11,000. The cysteine content was 30 mol% and the molar ratios of cadmium, copper and zinc were 49:49:2. The sulphydryl to cadmium ratio was 3. © 1979.