title: Specific soman-hydrolyzing enzyme activity in a clonal neuronal cell culture.
abstract: An enzymatic activity that specifically hydrolyzes the highly toxic organophosphorus anticholinesterase compound soman (pinacolyl methylphosphonofluoridate) has been identified and partially characterized in the clonal neuronal neuroblastoma-glioma hybrid NG108-15 cell line. Using the whole cell homogenate as the enzyme source and 1 mM substrate, the relative rate of hydrolysis of two other toxic anticholinesterase compounds sarin (isopropyl methylphosphonofluoridate) and tabun (ethyl-N-dimethyl phosphoramidocyanidate) is approximately one-tenth the rate of hydrolysis of soman, while DFP (diisopropyl phosphorofluoridate), paraoxon (p-nitrophenyl diethylphosphate), and a phosphinate PNMPP (p-nitrophenyl methyl (phenyl) phosphinate) are not hydrolyzed. Analysis of the kinetics of soman hydrolysis reveals two components of the enzyme activity with different affinities and reaction rates. Unlike previously reported enzymes of this type, this enzyme lacks chiral specificity and thus hydrolyzes both toxic and non-toxic soman stereoisomers at equal rates. The enzyme activity is stable at low temperature, found almost exclusively in the soluble fraction of these cells, and enhanced significantly by Mn2+ and by chemical differentiation of these cells in culture. The results suggest possible application of this enzyme for soman detection and/or detoxication, and use of the NG108-15 cell line to study the natural function(s) of enzymes of this type.
authors.affiliation: Biochemical Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425.
authors.forename: R
authors.initials: R
authors.lastname: Ray
authors.forename: L J
authors.initials: LJ
authors.lastname: Boucher
authors.forename: C A
authors.initials: CA
authors.lastname: Broomfield
authors.forename: D E
authors.initials: DE
authors.lastname: Lenz
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D043182:Carboxylesterase; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D002999:Clone Cells; D005910:Glioma; D006822:Hybrid Cells / Q000201:enzymology; D007700:Kinetics; D008297:Male; D008345:Manganese / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D009447:Neuroblastoma; D009474:Neurons / Q000201:enzymology*; D012999:Soman / Q000378:metabolism*
chemical_list: D008345:Manganese; D003994:Bucladesine; D012999:Soman; D002265:Carboxylic Ester Hydrolases; D043182:Carboxylesterase