Characterization of metallothionein-like proteins from zebra mussels (Dreissena polymorpha)

✍ Scribed by Kim A. High; Veronique J. Barthet; James W. McLaren; Jean-Simon Blais

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 103 KB
• Volume: 16
• Category: Article
• ISSN: 0730-7268
• DOI: 10.1002/etc.5620160604

✦ Synopsis

Zebra mussels (Dreissena polymorpha) are freshwater mollusks that have recently infested the Great Lakes ecosystem. Possessing a large capacity for filtration, these mussel populations act as bioconcentrators for contaminants, such as heavy metals, found in the Great Lakes ecosystem. Metallothionein is a low-molecular-weight, heavy metal-binding protein found in most living organisms. Characterization and partial purification of metallothionein-like Cd-binding proteins from zebra mussels were performed. Zebra mussels were exposed to 500 g/L Cd for 14 d. During the exposure period, two mussels were removed on alternate days for analysis of Cd-binding proteins. Gel-filtration high-performance liquid chromatography-microatomization-atomic absorption spectrophotometry results showed a single Cd-binding molecular weight protein fraction after 2 d of Cd exposure. After 10 d of Cd exposure, however, mussels exhibited an additional, higher molecular weight, Cd-binding protein fraction. The lower molecular weight metallothionein-like Cd-binding protein was further isolated and purified by acetone fractionation, Sephadex G75, and diethylaminoethyl anion-exchange chromatography. The quantities of Zn, Cu, and Cd in the anion-exchange metallothionein-like protein isoforms were determined by inductively coupled plasma-mass spectrometry. The ability to bioconcentrate heavy metals in a metallothionein-like form coupled with their large population in the Great Lakes make zebra mussels suitable for use in a freshwater biomonitoring program for aquatic metal contamination.