Abstract
The marine mussel, Mytilus edulis, possesses low molecular weight, metal-binding proteins which can be induced by and, in turn, bind mercury when individuals are exposed to low, but elevated concentrations of mercury as HgCl2. Induction of the proteins by exposure of mussels to copper, cadmium, or mercury is associated with enhanced tolerance to mercury toxicity. Mercury-binding proteins isolated from gills of mussels occur as two molecular weight variants of about 20-25 and 10-12 kdaltons, respectively, on Sephadex G-75. These have been designated as HgBP20 and HgBP10 following the nomenclature used for cadmium-binding proteins. HgBP20 represents the primary mercury-binding species. These exist as dimers which can be dissociated into subunits by treatment with 1% 2-mercaptoethanol. Further purification of HgBP20 by DEAE-cellulose ion-exchange chromatography resulted in the resolution of three major mercury-binding protein peaks; analysis of two of these showed that both had similar amino acid compositions with 26% half-cystine, 16% glycine, and very low levels of the aromatic amino acids phenylalanine and tyrosine (0.3-0.5%), histidine (0.4%), methionine (about 0.5%), and leucine (about 1%). These are similar to the compositions of proteins reported as mussel thioneins by others. Separation of HgBP20 by anion-exchange high-performance liquid chromatography resulted in the resolution of six peaks, indicating a more complex situation than was evident from DEAE-cellulose separations. Although not completely purified, these also contain cysteine- and glycine-rich proteins.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Frazier J. M. Cadmium-binding proteins in the mussel, Mytilus edulis. Environ Health Perspect. 1986 Mar;65:39–43. doi: 10.1289/ehp.866539. [DOI] [PMC free article] [PubMed] [Google Scholar]
- George S. G., Carpene E., Coombs T. L., Overnell J., Youngson A. Characterisation of cadmium-binding proteins from mussels, Mytilus edulis (L), exposed to cadmium. Biochim Biophys Acta. 1979 Oct 24;580(2):225–233. doi: 10.1016/0005-2795(79)90135-1. [DOI] [PubMed] [Google Scholar]
- Lerch K. Copper metallothionein, a copper-binding protein from Neurospora crassa. Nature. 1980 Mar 27;284(5754):368–370. doi: 10.1038/284368a0. [DOI] [PubMed] [Google Scholar]
- Ridlington J. W., Fowler B. A. Isolation and partial characterization of a cadmium-binding protein from the American oyster (Crassostrea virginica). Chem Biol Interact. 1979 May;25(2-3):127–138. doi: 10.1016/0009-2797(79)90041-3. [DOI] [PubMed] [Google Scholar]
- Viarengo A., Pertica M., Mancinelli G., Zanicchi G., Orunesu M. Rapid induction of copper-binding proteins in the gills of metal exposed mussels. Comp Biochem Physiol C. 1980;67C(2):215–218. doi: 10.1016/0306-4492(80)90021-0. [DOI] [PubMed] [Google Scholar]