XRF and XAFS analysis of electrophoretically isolated nondenatured proteins

Microbial metal reduction is relevant for developing bioremediation strategies for contaminated sites containing toxic metal compounds, but the molecular mechanisms involved and the regulation of those mechanisms are poorly understood. Metal reduction capability is microbe specific, yet the involvement of metalloproteins in the transport of electrons from electron donor molecules to electron acceptor molecules (i.e., to the metals to be reduced) is common to all metal-reducing organisms. A thorough understanding of the mechanisms involved in metal reduction by microbes, with a focus on their metalloproteins, will provide valuable information about the metal reduction capability of the organisms and could provide general insight into the mechanisms of metalloprotein expression and regulation in other microbial systems as well. We are developing methods for the efficient separation, detection, and quantification of metalloproteins. Electrophoretic methods for protein separation have been combined with x-ray fluorescence mapping and XAFS to determine the abundance and local chemical environment of iron within a cytochrome.