Analysis of human proteins that have an affinity to heavy metals by metal-chelating column chromatography.

To clarify the molecular basis of toxicities of industrial chemicals, it is demanded to develop appropriate methods whereby their cellular target molecules can be directly identified. In the present study, we focused on target proteins of heavy metals and established the method to detect them using a combination of metal-chelating column chromatography and a subsequent analysis by electrophoresis. Protein samples prepared from HeLa cells were applied to the Zn- or Cd-chelating column, and the bound proteins were analyzed by SDS-polyacrylamide gel electrophoresis followed by either silver staining, or fluorography when using radiolabel protein samples. Among several protein species trapped in the columns, a 36-kDa protein apparently has an affinity to both Zn and Cd, indicating the possibility that Cd can exchange essential Zn on this protein. These results suggest that the established method is useful for the target protein screening and further analyses of separated proteins.