Organophosphorous (OP) neurotoxins such as paraoxon, sarin, soman, VX, and Russian-VX, are a broad class of chemicals commonly used as pesticides and chemical warfare (CW) agents. Currently, over 100,000 tons of chemical warfare agents are stockpiled worldwide, and thousands-of-tons of OP pesticides are released into the environment annually. Enzymes known as phosphotriesterases, commonly called organophosphorous hydrolases (OPH), are capable of hydrolyzing OP and CW agents into harmless products. Because of their potential for destruction of these neurotoxins, organophosphorous hydrolases have recently become the focus of intense research efforts aimed at developing these enzymes into products for enzyme-based decontamination. However, these enzymes lack many of the desired properties such as solution solubility, thermal and pH stability, and substrate specificity for all of the potential applications of these enzymes. We have recently identified, cloned, expressed, purified, crystallized, and determined the x-ray structure of a novel OPH from an extremophile that has significant activity against the chemical warfare agent soman. The enzyme can be overexpressed in large quantities, and has desirable physical properties such as high solubility and thermostability compared to all of the other OPH enzymes under development. Therefore, our version of OPH holds significant promise for technological advancement in both civilian and military applications that require novel OPH enzymes for enzyme-based decontamination. Since large-scale expression and production using our current expression vectors and host strains would not be economically viable, and since our version of OPH has low activity toward V-agents, we propose to develop an economically viable, industrial scale production system for D. radiodurans OPH enzymes, and to enhance the catalytic potential of D. radiodurans OPH towards V-agents and other organophosphorous compounds using directed evolution genetic technology. ? ? ?
| Hawwa, Renda; Larsen, Sonia D; Ratia, Kiira et al. (2009) Structure-based and random mutagenesis approaches increase the organophosphate-degrading activity of a phosphotriesterase homologue from Deinococcus radiodurans. J Mol Biol 393:36-57 |
| Hawwa, Renda; Aikens, John; Turner, Robert J et al. (2009) Structural basis for thermostability revealed through the identification and characterization of a highly thermostable phosphotriesterase-like lactonase from Geobacillus stearothermophilus. Arch Biochem Biophys 488:109-20 |
