title: Aging of soman-inhibited acetylcholinesterase: PH-rate profiles and temperature dependence in absence and in presence of effectors.
abstract: The influence of pH and temperature upon the dealkylation (aging) of soman-inhibited acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) was investigated. The pH-rate profile, as measured at 5 degrees C, shows a maximum aging rate at pH 5.0 and indicates the involvement of two ionizable groups with pKa values of 6.0 and 4.5. The pH-rate profile was not changed essentially by the two effector compounds, semicarbazide and HH54. the activation energy of aging at pH 7.0 was determined as to 6.12 x 10(4) J/mol; it was lowered by the accelerator of aging semicarbazide to 5.28 x 10(4) J/mol and increased to 9.42 x 10(4) J/mol by the retarding compound HH54.
mesh_terms: D002800:Cholinesterase Inhibitors; D003640:Dealkylation; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008782:Methylurea Compounds / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D012663:Semicarbazides / Q000494:pharmacology; D012999:Soman / Q000494:pharmacology*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D002800:Cholinesterase Inhibitors; D008782:Methylurea Compounds; D009943:Organophosphorus Compounds; D012663:Semicarbazides; C029472:(3,4-bispyridinium-1,1-dimethyl)urea diiodide; D012999:Soman