title: Purification and properties of a diisopropyl-fluorophosphatase from squid Todarodes pacificus steenstrup.
abstract: A diisopropyl-fluorophosphatase (DFPase) was purified from brain and ganglia of squid Todarodes pacificus steenstrup. The DFPase had a preference in hydrolysis toward diisopropylphosphorofluoridate (DFP). It also was able to hydrolyze O-1,2,2-trimethylpropyl methylphosphofluoridate (soman) and O-isopropyl methylphosphonofluoridate (sarin) at nearly equal hydrolytic rates but only 1/10 that of DFP. The hydrolytic activity toward diethyl-p-nitrophenylphosphate (paraoxon) was very low compared with DFP, soman, and sarin. The DFPase was purified 330-fold to a specific activity of 18,300 n mol/min/mg protein. Its molecular weight was 34,000 dalton determined by gel-filtration chromatography. Mn2+ stimulation of the DFPase was not observed when DFP and soman were the substrates, but with sarin, the rate increased onefold in the presence of 1.0 mM of Mn2+. Ethylenediamine tetraacetic acid disodium (EDTA-Na2) at 0.05 M inhibited the DFPase activity about 30%. It could be concluded that this DFPase belongs to the squid-type DFPase.
authors.affiliation: Institute of Pharmacology and Toxicology, Beijing, China.
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Xiao
authors.forename: S
authors.initials: S
authors.lastname: Mu
mesh_terms: D000818:Animals; D043303:Aryldialkylphosphatase; D001921:Brain / Q000201:enzymology; D002384:Catalysis; D002850:Chromatography, Gel; D049832:Decapodiformes / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004950:Esterases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism*; D017952:Ganglia, Invertebrate / Q000201:enzymology; D007531:Isoflurophate / Q000378:metabolism; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D044345:Phosphoric Triester Hydrolases; D011506:Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D011506:Proteins; D007531:Isoflurophate; D008345:Manganese; D004492:Edetic Acid; D004950:Esterases; D044345:Phosphoric Triester Hydrolases; D043303:Aryldialkylphosphatase; C020061:diisopropyl-fluorophosphatase