Ferritin and hemocyanin: 210Po molecular traps in marine fish, oyster and lobster
Résumé
The relative degree of binding of 210Po with fish, mollusc and crustacean ferritins was investigated. Comparison of 210Po concentrations in the purified ferritins from liver of the Atlantic mackerel Scomber scombrus and from the visceral mass of oysters Crassostrea gigas confirmed the high affinity of polonium for these iron-containing proteins. The ferritin fraction in lobster Homarus gammarus hepatopancreas contained an order of magnitude more 210Po than pure ferritin from fish and oyster; however, the hepatopancreatic ferritin fraction was not pure and it also contained the respiratory protein hemocyanin. A high performance size-exclusion chromatography analysis further revealed the important contribution of hemocyanin to 210Po fixation in lobster. The combined 210Po binding capacity of ferritin and hemocyanin in lobster hepatopancreas most probably accounts for the very high 210Po concentrations found in the hepatopancreas of many higher crustaceans.