Silver staining for carboxymethylated metallothioneins in polyacrylamide gels.
A sensitive method for detecting metallothioneins (MTs) by use of silver staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of carboxymethylated MTs was developed. Carboxymethylation of metallothioneins is indispensable because it prevents their aggregation, thereby allowing each of them to be detected as a single band by SDS-PAGE. However, when the gel was subjected to the silver-staining method of C. R. Merril, D. Goldman, S. A. Sedman, and M. H. Ebert [(1981) Science 211, 1437-1438], the image of carboxymethylated purified MTs was totally negative. Pretreatment of the gel with 1% sodium thiosulfate just prior to the silver-staining procedure successfully reversed the negative image of carboxymethylated MTs. Further, they could be detected with a limit of nanogram levels per lane. This method can be applied to MTs in cell extracts from cultured cell lines treated with cadmium or to those from liver of cadmium-intoxicated mice.
D000818:Animals; D003600:Cytosol / Q000032:analysis; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D066298:In Vitro Techniques; D008099:Liver / Q000032:analysis; D008668:Metallothionein / Q000032:analysis*; D051379:Mice; D008807:Mice, Inbred BALB C; D012834:Silver; D013194:Staining and Labeling; D013885:Thiosulfates; D014407:Tumor Cells, Cultured / Q000032:analysis
D013885:Thiosulfates; D012834:Silver; D008668:Metallothionein; C017717:sodium thiosulfate