Inorganic Mercury Poses Damage Risk to Key Cell Processes

In what’s being called the first study to compare the effects of inorganic and organic mercury compounds on a model organism, a team from the University of Georgia, Athens, sought to understand how these compounds affect molecular processes. Examining the effects of mercury at the biochemical, physiological and proteomic levels, the researchers published their findings, “Organic and Inorganic Mercurials Have Distinct Effects on Cellular Thiols, Metal Homeostasis, and Fe-binding Proteins in Escherichia coli,” in the Journal of Biological Inorganic Chemistry.

For centuries, inorganic mercury was used to fight infections. Today, it is found primarily in dental amalgam. Organic mercury, on the other hand, is found in many fish species, and overexposure is associated with neurological disease — though its apparent risk is less than that posed by inorganic mercury, which is known to cause neurological, kidney and autoimmune diseases. Using a common strain of E. coli as the model cellular system, the researchers exposed cells to both compounds. Next, they measured thiol levels (an essential metal and protein that naturally binds essential metals). It was discovered that inorganic mercury was more efficient at removing iron from iron-dependent proteins than organic mercury, leading to the conclusion that inorganic mercury causes more damage at lower concentrations than organic mercury.