Studies of radicals formed by oxidative damage and by electrons

化学自由基是含有未成对电子的物质。当原子间的键被破坏，或者当电子从中性分子中移除或加入时，它们就会形成。自由基具有很强的活性，在工业和生物过程中经常催化其他分子的反应。这项建议是为了更好地了解它们的行为和反应性。我们集中研究两种自由基：(a)在活细胞中产生的多肽自由基，(b)在分子簇中加入电子形成的自由基。细胞中的自由基：活细胞中存在多种自由基。它们有有益的作用，但也会造成氧化损伤，必须控制它们的浓度。含硫分子谷胱甘肽（GSH）对此负有部分责任。它是通过放弃一个氢原子，自己变成一个自由基GS来实现的。这项建议的一个方面是检查谷胱甘肽的化学性质，它会影响这一控制过程的效率。此外，我们希望检查含硫自由基与蛋白质反应的速率，因为这种过程发生在某些酶中。电子和簇：电子附着在中性分子上在大气化学、绝缘材料、气体放电、等离子体和辐照系统中具有重要的实际意义。这个建议的一部分是关于宇宙射线在极地地区形成的电子。它们可能会附着在平流层冰云中的分子上，并产生能够破坏臭氧的自由基。这种可能性正在与魁北克舍布鲁克的其他科学家合作进行研究。以及德国的j<e:1>利希。其他工作涉及电子与中性分子簇的结合，以及当电子存在时簇如何改变形状。形状将通过使用西网格计算机网络和我们自己的较小网络的计算机建模来确定。美国约翰霍普金斯大学的合作者将测量电子被束缚的强度。

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.