Studies of radicals formed by oxidative damage and by electrons

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Chemical radicals are species containing unpaired electrons. They can be formed when bonds between atoms are broken or when electrons are removed from or added to a neutral molecule. Radicals are very reactive and often catalyse reactions of other molecules in industrial and biological processes. This proposal is concerned with obtaining a better understanding of their behaviour and reactivity. We concentrate on radicals of two kinds: (a) radicals of peptides, which occur in living cells, and (b) radicals formed by the addition of electrons to clusters of molecules.   Radicals occurring in cells: Many kinds of radical occur in living cells. They have beneficial effects but also cause oxidative damage, and their concentrations must be controlled. The sulfur containing molecule glutathione (GSH) is partly responsible for this. It does so by giving up a hydrogen atom and itself becoming a radical, GS. One aspect of this proposal is to examine the chemical properties of GSH which affect the efficiency of this control process. In addition we wish to examine the rate at which a sulfur containing radical can react with a protein, since processes of this kind occur in some enzymes. Electrons and Clusters: The attachment of electrons to neutral molecules is of practical importance in the chemistry of the atmosphere, insulating materials, gas discharges, plasmas and irradiated systems. One part of this proposal is concerned with electrons formed by cosmic rays in the Polar Regions. It is possible that these may attach to molecules in stratospheric ice clouds and create radicals which can destroy ozone. This possibility is being examined in collaboration with other scientists at Sherbrooke, Que. and Jülich, Germany. Other work is concerned with the binding of electrons to clusters of neutral molecules, and how the clusters change shape when the electron is present. Shapes will be determined by computer modeling using the Westgrid computer network and our own smaller network. The strength with which electrons are held will be measured by collaborators at Johns Hopkins in the USA.