title: Organophosphate hydrolases as catalytic bioscavengers of organophosphorus nerve agents.
abstract: Bioscavengers are molecules able to neutralize neurotoxic organophosphorus compounds (OP) before they can reach their biological target. Human butyrylcholinesterase (hBChE) is a natural bioscavenger each molecule of enzyme neutralizing one molecule of OP. The amount of natural enzyme is insufficient to achieve good protection. Thus, different strategies have been envisioned. The most straightforward consists in injecting a large dose of highly purified natural hBChE to increase the amount of bioscavenger in the bloodstream. This proved to be successful for protection against lethal doses of soman and VX but remains expensive. An improved strategy is to regenerate prophylactic cholinesterases (ChE) by administration of reactivators after exposure. But broad-spectrum efficient reactivators are still lacking, especially for inhibited hBChE. Cholinesterase mutants capable of reactivating spontaneously are another option. The G117H hBChE mutant has been a prototype. We present here the Y124H/Y72D mutant of human acetylcholinesterase; its spontaneous reactivation rate after V-agent inhibition is increased up to 110 fold. Catalytic bioscavengers, enzymes capable of hydrolyzing OP, present the best alternative. Mesophilic bacterial phosphotriesterase (PTE) is a candidate with good catalytic efficiency. Its enantioselectivity has been enhanced against the most potent OP isomers by rational design. We show that PEGylation of this enzyme improves its mean residence time in the rat blood stream 24-fold and its bioavailability 120-fold. Immunogenic issues remain to be solved. Human paraoxonase 1 (hPON1) is another promising candidate. However, its main drawback is that its phosphotriesterase activity is highly dependent on its environment. Recent progress has been made using a mammalian chimera of PON1, but we provide here additional data showing that this chimera is biochemically different from hPON1. Besides, the chimera is expected to suffer from immunogenic issues. Thus, we stress that interest for hPON1 must not fade away, and in particular, the 3D structure of the hPON1 eventually in complex with OP has to be solved.
authors.affiliation: Département de Toxicologie, Institut de Recherches Biomédicales des Armées, 38700 La Tronche, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Trovaslet-Leroy
authors.forename: Lucie
authors.initials: L
authors.lastname: Musilova
authors.forename: Frédérique
authors.initials: F
authors.lastname: Renault
authors.forename: Xavier
authors.initials: X
authors.lastname: Brazzolotto
authors.forename: Jan
authors.initials: J
authors.lastname: Misik
authors.forename: Ladislav
authors.initials: L
authors.lastname: Novotny
authors.forename: Marie-Thérèse
authors.initials: MT
authors.lastname: Froment
authors.forename: Emilie
authors.initials: E
authors.lastname: Gillon
authors.forename: Mélanie
authors.initials: M
authors.lastname: Loiodice
authors.forename: Laurent
authors.initials: L
authors.lastname: Verdier
authors.forename: Patrick
authors.initials: P
authors.lastname: Masson
authors.forename: Daniel
authors.initials: D
authors.lastname: Rochu
authors.forename: Daniel
authors.initials: D
authors.lastname: Jun
authors.forename: Florian
authors.initials: F
authors.lastname: Nachon
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D043303:Aryldialkylphosphatase / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D055162:Biocatalysis; D016466:CHO Cells; D002619:Chemical Warfare Agents / Q000737:chemistry / Q000633:toxicity; D002801:Cholinesterase Reactivators / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D004355:Drug Stability; D005260:Female; D006868:Hydrolysis; D009154:Mutation; D009943:Organophosphorus Compounds / Q000737:chemistry* / Q000633:toxicity; D044345:Phosphoric Triester Hydrolases / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D002619:Chemical Warfare Agents; D002801:Cholinesterase Reactivators; D009943:Organophosphorus Compounds; D000110:Acetylcholinesterase; D044345:Phosphoric Triester Hydrolases; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human