Enzymic Detoxification of Organophosphate Nerve Agents

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The long-term objective for the research described in this proposal is the design and construction of a robust catalytic system that can be exploited for the decontamination, destruction, and detection of organophosphate nerve agents. The nerve agents sarin (GB), soman (GD), and VX are among the most toxic and deadly nerve agents ever reported. Since these compounds are easy to synthesize and distribute, they represent a serious threat to the health and well being of civilized societies. In order to prepare a system that can detoxify organophosphate nerve agents, we will manipulate and enhance the enzymatic power of wild type proteins to serve as catalysts for the recognition and hydrolytic turnover of these highly toxic materials. It has been demonstrated that the catalytic machinery embedded within the active sites of the bacterial phosphotriesterase and alpha-prolidase are capable of hydrolyzing certain organophosphate nerve agents such as paraoxon at the diffusion controlled limit. The active site structures of these enzymes will be re- engineered through rational and combinatorial mutagenesis techniques to create libraries of mutant enzymes with altered catalytic properties. These enzyme libraries will be efficiently evaluated with high throughput screening protocols using fluorescence and visible spectroscopy with chiral analogs of GB, GD, and VX. The catalytic activities with the restricted nerve agents will be optimized through a direct collaboration with the DeFrank group at the Aberdeen Proving Ground. The structural analyses of the wild type and mutant proteins will be conducted by the Holden group at Wisconsin.