Comparison of Ca2+/calmodulin-dependent protein kinase II purified from control and diisopropyl phosphorofluoridate (DFP)-treated hens |
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Authors: | Ram P Gupta Mohamed B Abou-Donia |
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Institution: | (1) Department of Pharmacology, Duke University Medical Center, P.O. Box 3813, Durham, North Carolina, USA |
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Abstract: | Diisopropyl phosphorofluoridate (DFP) produces type I organophosphorus ester-induced delayed neurotoxicity in humans and sensitive animal species. This is accompanied by enhanced Ca2+/CaM-dependent protein kinase II (CaM-kinase II) activity, and 125I]calmodulin binding to CaM-kinase II in DFP-treated hen brain supernatant without increase in the enzyme quantity. We have purified CaM-kinase II from control and DFP-treated hen whole brains and compared various physical and biochemical properties. The two enzymes exhibited similar properties in many respects. However, there was a decrease in calcium-independent protein kinase II activity after autophosphorylation, and an increase in K0.5 for free calcium and calmodulin of enzyme purified from DFP-treated hen brains. This change in kinetic parameters may result in greater percentage of total CaM-kinase II present in unphosphorylated form, which is consistent with the increased autophosphorylation of CaM-kinase II and 125I]calmodulin binding in the brain supernatant of DFP-treated hens.Abbreviations used CaM
calmodulin
- CaM-kinase II
Ca2+/calmodulin-dependent protein kinase II
- MAP-2
microtubule associated protein-2
- DFP
diisopropylphosphorofluoridate
- DTT
dithiothreitol
- EDTA
ethylenediaminetetraacetic acid
- EGTA
ethylene glycol-bis( -aminoethyl ether) N,N,N ,N -tetraacetic acid
- NEPHGE
nonequilibrium pH gradient electrophoresis
- OPIDN
organophosphorus ester-induced delayed neurotoxicity
- PIPES
1,4-piperazinediethanesulfonic acid
- PMSF
phenylmethylsulfonyl fluoride
- SDS-PAGE
sodium dedecyl sulfate-polyacrylamide gel electrophoresis
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St. aureus V8 protease
Staphylococus aureus V8 protease
- TOCP
tri-O-cresyl phosphate
- TPCK
N-tosyl-I-phenylalanine chloromethyl ketone |
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Keywords: | CaM-kinase II diisopropyl phosphorofluoridate hen calmodulin protein kinase delayed neurotoxicity |
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