Development of Inhibitors of the Aging Process of Organophosphate Adducts of AChE

Development of Inhibitors of the Aging Process of Organophosphate Adducts of AchE. The goal of this proposal is to demonstrate that it is possible to control the reactivation of the enzyme acetylcholinesterase (AChE) via a macromolecule binding to it to prevent the organophosphate adduct with nerve agent (AChE*NA) from aging. To do this, we will select macromolecular reagents (nucleic acid ligands or aptamers and antibodies) that bind to AChE*NA and lock the enzyme in a conformation that prevents the process of aging, thereby facilitating reactivation and extending the window for therapeutic intervention. Our studies are designed to provide a basic science foundation for therapeutic approaches that would overcome one of the major limitations in the treatment of organophosphate toxicity, i.e., formation of aged adducts of AChE that are resistant to reactivation. We have identified solid-state immobilization conditions that inhibit the aging process and we have demonstrated that both DFP and a rapidly aging analog of soman are resistant to aging under these conditions. Aging depends on the specific orientation of substituents around phosphorous and the establishment of a hydrogen bonding network within the AChE active site; thus, we propose to isolate aptamers that could stabilize the conformation of AChE in which the aging process is unfavorable and thereby would act as inhibitors of aging. Ultimately, we expect the structural and mechanistic insight gained, as well as availability of these aptamers as research tools, to lead to the development of small molecules that would induce similar conformational changes to prevent aging and allow therapeutic intervention to occur within a longer timeframe