"ENVIRONMENTAL ASPECTS OF GSH REDOX REGULATION AND OXIDATIVE STRESS",

M. Hepel, J. Dallas,

The redox regulating glutathione (GSH) system plays a vital role in living organisms in protecting cells against oxidative damage. There are indications that susceptibilities of different individuals to environmentally induced diseases (diabetes, brain damage and cancer) are associated with GSH level in cells and body fluids. The interactions of GSH with various toxicants are suspected to influence the regulating capacity of GSH/GSSG system. We have investigated GSH interactions with toxic heavy metal ions^1,2 on electrodes using electrochemical quartz crystal nanogravimetry and immittance spectroscopy. W report here on Hg(II)-GSH interactions. We have found that the modification of a Au substrate with self-assembled glutathione (Au-SG) film creates a framework of confined-space microenvironment with ion-channels for enhanced Hg²⁺-GSH interactions and rich charge transfer reactivity. The reduction of Hg(II) on a Au-SG piezoelectrode has been investigated in two regimes of ion channel permeation of the modifying film, at opened and closed ion channels. The maximum surface coverage determined from upd-Hg mass: q_Hg = 0.31. The chelation of Hg²⁺ to carboxylate moieties at the outer film-solution boundary and place–exchange of Hg/Au atoms at the sulphur root of adsorbed GSH have been further investigated³ by ab initio quantum mechanical calculations.

The electronic structure of Hg²⁺-GSH chelate was found to mimic that of Ca²⁺-GSH chelate. The implications of this finding for studies of environmental effects on susceptibility to degenerative diseases should be of great significance.