Bioscavenging of organophosphate (OP) by human proteins is emerging as a promising medical interventionfor prophylaxis and post-exposure treatment against chemical warfare nerve agents. The best-.studiedbioscavengers (BSCs) to date, meeting considerable success in pre-clinical research, are humancholinesterases (ChEs). However, ChEs, which are highly efficient in binding and sequestering OPs, are alsoinactivated by the toxins and therefore administration of large amounts of protein is necessary for fullprotection, raising the question of the practicality of this approach. The development of improved biocatalysts(BCT) (paraoxonase 1) that can catalytically degrade OPs may address this concern.The proposed effort offers a novel means to biomanufacture recombinant BSCs and BCTs based on thehuman proteins, butyrylcholinesterase and paraoxonase 1. In collaboration with the other projectsparticipating in the Center, the capacity of these proteins to sequester or hydrolyze OPs will be improved bysubjecting their genes to either random in vitro evolution or rational mutagenesis. To that end, we willundertake high-throughput screening of mutant enzyme libraries, in particular to improve the stability anddrug-like properties of paraoxonase I. In addition, post-translational glycosylation systems or proteinPEGylation procedures will be developed to increase the circulating lifetimes and to eliminate potentialantigenicity of proteins produced in non-human, recombinant organisms. The OSU team (Project 6) willutilize the transgenic microalgae, Chlamydomonas reinhardtii, to produce pilot-plant scale quantities of theseproducts for direct recovery from the culture media. In addition, they will optimize this production system forscale-up to commercial production capacity. The primary significance of this project is that it will developpilot-plant systems for the production of enhanced, second-generation, improved ChE-based BSC and BCTproducts suitable for human clinical trials.
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