Cadmium-Binding Proteins in the Mussel, Mytilus edulis

Frazier, John M.

doi:10.2307/3430160

Cited by 10 publications

(11 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4). These values are similar to those of the half-cystine rich cadmium-binding proteins (8,11). A larger-scale purification of the unreduced HgBP20 fraction on DEAE-cellulose also resulted in the resolution of three major peaks corresponding to those above, but with considerably more overlap.…”

Section: Resultssupporting

confidence: 72%

Mercury-Binding Proteins from the Marine Mussel, Mytilus edulis

Roesijadi¹

1986

Environmental Health Perspectives

View full text Add to dashboard Cite

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.

show abstract

Section: Resultssupporting

confidence: 72%

Mercury-Binding Proteins from the Marine Mussel, Mytilus edulis

Roesijadi¹

1986

Environmental Health Perspectives

View full text Add to dashboard Cite

show abstract

“…Box 12233, Research Triangle Park, NC 27709. tained a soluble cadmium-binding protein peak with an estimated molecular weight of 21,000 by Sephadex column chromatography. This value is about twice that reported for mammalian MT by this method (10) but similar to that reported from MT-like cadmium-binding proteins from mussels (2,6,12). The present study was undertaken to further characterize this protein peak in kidneys of the scallop Placopecten magellanicus and to determine whether it was a monomer or represented an aggregated form of lower molecular weight protein components.…”

Section: Introductionsupporting

confidence: 89%

Isolation and partial characterization of a high molecular weight Cd/Zn-binding protein from the kidney of the scallop Placopecten magellanicus: preliminary studies.

Fowler¹,

Megginson²

1986

Environ Health Perspect

View full text Add to dashboard Cite

Exposure of the scallop Placopecten magellanicus to 20 ppb Cd2+ in seawater for 7 weeks results in a 7-fold increase in the kidney cytosol content of Cd and 5-fold increase in Zn. Sephadex G-75 column chromatography of the kidney cytosol showed that most of the Cd and Zn were bound to a protein complex with an estimated molecular mass of 45,000 daltons. Further purification of this complex by DEAE A-25 column chromatography disclosed the presence of five peaks with varying degrees of affinity for the ion-exchange resin. One of these peaks (III) was successfully rechromatographed by ion-exchange chromatography and further purified by HPLC using a gel-permeation column. The resultant protein peak which was resistant to disaggregation by 20 mM dithiothreitol gave a preliminary amino acid composition with cysteine, glycine, alanine, and lysine as the major amino acids. The aromatic amino acid phenylalanine was also present. The ultraviolet absorption spectrum gave a 250/280 nm ratio of 2.5:1. Metal analysis of the purified protein showed that it contained Cd, Zn, and Cu in ratios of 1:1:1. Results of these studies indicate that scallop kidney produces a protein complex which appears to share both similarities with mammalian metallothionein with respect to the presence of both Cd and Zn but different with respect to apparent size, amino acid composition, and ultraviolet absorption spectrum.

show abstract

“…Previous studies from a number of laboratories (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) have demonstrated the presence of cadmium-binding proteins (CdBP) in marine molluscs with properties that are both similar to and different from mammalian methallothionein (MT) (11,12). As previously noted (11), basic research on nonmammalian metal-binding proteins is of great potential value in elucidating not only the evolutionary pathway(s) of MT but also in gaining insight into its as yet unknown normal biological function.…”

Section: Introductionmentioning

confidence: 99%

“…The Sephadex G-75 column (5.0 x 50 cm) was eluted with 0.06 M or 0.01 M Tris-HCI buffer (pH 7.9 or 8.6), and fractions were monitored for Cd and for absorbance at 280 and 254 nm by using a Perkin-Elmer Model 305B atomic absorption spectrophotometer and ISCO Type 6 flow-through UV monitor, respectively. The peak Cd fractions corresponding to the CdBP described by Ridlington (9). Gels were stained either with Coomassie Blue or by the silver stain method using Bio-Rad silver stain kits.…”

Section: Isolation Of Oyster Cdbpmentioning

confidence: 99%

Purification and Characterization Studies of Cadmium-Binding Proteins from the American Oyster, Crassostrea virginica

Fowler¹,

Engel²,

Brouwer³

1986

Environmental Health Perspectives

View full text Add to dashboard Cite

The previously reported low molecular weight cadmium-binding protein (CdBP) from the American oyster, Crassostrea virginica, has been further purified and characterized by improved technical methods. The internal organ distribution ofthe protein within the oyster and effects of life cycle/season on CdBP production also have been evaluated. CdBP isolated by extended ion-exchange gradients or double ion-exchange chromatography followed by HPLC analysis possesses an electrophoretic R,of about 0.7 and contains relatively little Zn, as previously reported. Cysteine, lysine, and glycine are the dominant amino acids. When ionexchange columns are developed with NaCl gradients, the aromatic residues tryptophan, tyrosine, and phenylalanine are found to be present, but these may be largely removed depending upon whether the protein is denatured and carboxymethylated prior to analysis. The ultraviolent absorption spectrum of CdBP also was variable, with 250/280 nm ratios ranging from 17:1 immediately after ion-exchange chromatography to 2:1 following concentration procedures. Internal organ distribution studies showed that the visceral mass contained most of the Cd present with lesser amounts in the gills and mantle. In contrast with mammals, CdBP accounts for only about 30%o of the total cell Cd burden in these tissues. Cu displacement of Cd from the protein is a particular problem during the summer spawning season and appears to stem from altered Cu metabolism during this period. Relative oyster dormancy during the winter also reduces CdBP production in response to Cd, and the protein is obtained most readily during the fall and spring. In summary, CdBP shares both similarities and differences with MT, and the magnitude of these parameters depends greatly on both the biology of the oyster and technical procedures used to isolate/characterize the protein.

show abstract

Cadmium-Binding Proteins in the Mussel, Mytilus edulis

Cited by 10 publications

References 10 publications

Mercury-Binding Proteins from the Marine Mussel, Mytilus edulis

Mercury-Binding Proteins from the Marine Mussel, Mytilus edulis

Isolation and partial characterization of a high molecular weight Cd/Zn-binding protein from the kidney of the scallop Placopecten magellanicus: preliminary studies.

Purification and Characterization Studies of Cadmium-Binding Proteins from the American Oyster, Crassostrea virginica

Contact Info

Product

Resources

About