Multiple biophysical methods demonstrate that silver effectively metallates Pseudomonas aeruginosa apo-azurin in solution. X-ray crystallography of the silver-modified protein reveals that silver binds to azurin at the traditional copper mediated active site with nearly identical geometry. Cyclic voltammetry indicates that the silver adduct is redox inert. Our results suggest that a potential mechanism for the microbial toxicity of silver is the deactivation of copper oxidoreductases by the effective binding and structural mimicry by silver without the corresponding function.
Bibliographical noteFunding Information:
This work was supported by The University of Akron . We wish to thank the National Science Foundation for funds used to purchase the Bruker Apex II Duo CCD X-ray diffractometer (CHE-0840446) used in this research. We thank the Kresge Foundation and donors to the Kresge Challenge Program at The University of Akron for funds used to purchase the NMR instrument used in this work. We also wish to thank the Center for Silver Therapeutics Research at The University of Akron. We thank the Swenson Family Foundation (UMD) for funding and student stipends. Finally, we would like to thank John H. Richards, California Institute of Technology, and Yi Lu of the University of Illinois at Urbana-Champaign for the kind gift of the azurin gene.
- Silver ion