Partitioning of copper among copper-binding proteins in the mussel Mytilus edulis exposed to soluble copper

Partitioning of copper among copper-binding proteins was evaluated in digestive glands of Mytilus edulis exposed to soluble copper. Groups of mussels were held in flow-through bioassay systems and exposed to 25 μg Cu liter^?1 for up to 21 weeks. At three-week intervals, groups of 25 mussels were removed and the digestive glands were analyzed for copper-binding proteins by gel-permeation chromatography and atomic absorption spectrometry.Chronic exposure to copper resulted in increased amounts of copper in the low molecular weight (LMW) protein fraction, which contains metallothioneins, and in the high molecular weight (HMW) protein fraction, which contains metalloenzymes. Concentrations of copper in the LMW protein fraction increased and then appeared to plateau with long exposure times, whereas those in the HMW protein fraction continued to increase with exposure time.