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Science Highlight
Penner-Hahn Research


21 December 2005

  Insight into Lead Toxicity

T.-C. Weng, & J.E. Penner-Hahn, University of Michigan
J.S. Magyar & H.A. Godwin, Northwestern University


Research performed at SSRL has provided insight into why lead is so damaging to the healthy development of young children. Scientists from the University of Michigan and Northwestern University used x-ray absorption spectroscopy at SSRL to understand how lead can interfere with proteins that help transform DNA blueprints into working proteins that run the body.

Gene expression proteins are the cell's contractors; they follow a gene's directions to initiate processes that will lead to building finished proteins. Many gene expression proteins contain a zinc atom that can be replaced by a lead atom if a person is exposed to too much lead. Normally, zinc attaches to four sulfur atoms, causing the protein to adopt a structure that binds to DNA. However, the researchers found that lead attaches to only three of the sulfur atoms. This difference in structure may explain the observation that when lead binds to gene expression proteins instead of zinc, the proteins do not form the proper structure and thus fail to bind properly to DNA to begin working with the blueprints.

J. S. Magyar, T.-C. Weng, C. M. Stern, D. F. Dye, B. W. Rous, J. C. Payne, B. M. Bridgewater, A. Mijovilovich, G. Parkin, J. M. Zaleski, J. E. Penner-Hahn and H. A. Godwin, "Reexamination of Lead(II) Coordination Preferences in Sulfur-Rich Sites: Implications for a Critical Mechanism of Lead Poisoning", J. Am. Chem. Soc. 127, 9495 (2005)