|Combine Metal K-edge XAS/EXAFS and Ligand (S) K-edge XAS Methods to Understand The Metal Ion Specific Response of NikR Proteins|
|Full Author List||Heidi Hu, Michael Maroney, Britt Hedman, Keith Hodgson, Edward Solomon|
NikR protein is a nickel-responsive regulatory protein involved in controlling the concentration intracellular Ni pool in E. coli. Metal K-edge XAS/EXAFS on different metal variant of NikR provided geometric information that different metal ions occupied different binding sites in the protein. Ligand (sulfur) K-edge XAS was then used to study the electronic structures of the metal binding sites, and showed that metal-sulfur bond covalencies can actually affect the metal sites' coordination number and ligand types, thus affect the conformation of the protein folding, which explains the ion specific behavior of NikR.