title: Nerve agent hydrolysis activity designed into a human drug metabolism enzyme.
abstract: Organophosphorus (OP) nerve agents are potent suicide inhibitors of the essential neurotransmitter-regulating enzyme acetylcholinesterase. Due to their acute toxicity, there is significant interest in developing effective countermeasures to OP poisoning. Here we impart nerve agent hydrolysis activity into the human drug metabolism enzyme carboxylesterase 1. Using crystal structures of the target enzyme in complex with nerve agent as a guide, a pair of histidine and glutamic acid residues were designed proximal to the enzyme's native catalytic triad. The resultant variant protein demonstrated significantly increased rates of reactivation following exposure to sarin, soman, and cyclosarin. Importantly, the addition of these residues did not alter the high affinity binding of nerve agents to this protein. Thus, using two amino acid substitutions, a novel enzyme was created that efficiently converted a group of hemisubstrates, compounds that can start but not complete a reaction cycle, into bona fide substrates. Such approaches may lead to novel countermeasures for nerve agent poisoning.
authors: Department of Biochemistry/Biophysics and Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
authors: Andrew C
authors: AC
authors: Hemmert
authors: Tamara C
authors: TC
authors: Otto
authors: Roberto A
authors: RA
authors: Chica
authors: Monika
authors: M
authors: Wierdl
authors: Jonathan S
authors: JS
authors: Edwards
authors: Steven M
authors: SM
authors: Lewis
authors: Steven L
authors: SL
authors: Lewis
authors: Carol C
authors: CC
authors: Edwards
authors: Lyudmila
authors: L
authors: Tsurkan
authors: C Linn
authors: CL
authors: Cadieux
authors: Shane A
authors: SA
authors: Kasten
authors: John R
authors: JR
authors: Cashman
authors: Stephen L
authors: SL
authors: Mayo
authors: Philip M
authors: PM
authors: Potter
authors: Douglas M
authors: DM
authors: Cerasoli
authors: Matthew R
authors: MR
authors: Redinbo
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain; D002619:Chemical Warfare Agents / Q000378:metabolism / Q000493:pharmacokinetics*; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D009154:Mutation; D009943:Organophosphorus Compounds / Q000378:metabolism / Q000493:pharmacokinetics*; D011487:Protein Conformation
chemical_list: D002619:Chemical Warfare Agents; D009943:Organophosphorus Compounds; D002265:Carboxylic Ester Hydrolases; C474609:CES1 protein, human