EPR Studies of Copper Dynamics in Doped Biological Crystals

电子顺磁共振（EPR）光谱将用于研究铜在生物模型晶体中的动力学行为。在这些系统的动态过程的知识提供了重要的洞察不寻常的铜配位的稳定性，如那些经常发现在生物大分子。动态过程的特征通常用一个临界温度来描述，在这个临界温度之上，运动变得足够快，可以平均出单个物种的特征、转变速率、活化能和可能状态的能量差。该项目将确定这些参数，这样做将提供对金属配合物的势能表面的定性和定量理解。这有助于更好地理解金属蛋白中铜的稳定性与结构之间的关系。以前缺少合适的铜模型系统

Electron Paramagnetic Resonance (EPR) spectroscopy will be utilized to study dynamic behavior exhibited by copper in crystals of biological models. Knowledge of dynamic processes in these systems gives important insight into the stability of unusual copper coordination like those frequently found in biological macromolecules. Features of the dynamic processes are normally described by a critical temperature, above which motion becomes rapid enough to average out characteristics of individual species, rate(s) of transition, activation energy (ies) and energy differences of the possible states. This project will determine these parameters and in doing so will provide both a qualitative and quantitative understanding of the potential energy surfaces of the metal complex. This leads to a better understanding of the relationship between stability and structure of copper in metalloproteins. The previous lack of suitable copper model systems showing dynamic behavior has been circumvented by the realization in a survey of copper-doped cadmium-crystals that when Cu2+ replaces Cd2+, the copper complex, in all cases, exhibits dynamic behavior. This is most likely the result of the cadmium ion posessing a larger cage of surrounding ligands than the replacing copper ion. Four such model crystal systems have been initially identified, Cu2+-doped into Cd2+-histidine, Cd2+-theophylline, Cd2+-glycylglycine HCl and Cd2+-glutamate, and are proposed here for detailed EPR investigations. The long term objective is to use this information in studies where copper can act as a surrogate in cadmium-binding proteins and in the newly discovered cadmium-dependent carbonic anhydrase.