Comparison of Ca2+/calmodulin-dependent protein kinase II purified from control and diisopropyl phosphorofluoridate (DFP)-treated hens.
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.
Duke University Medical Center, Department of Pharmacology, Durham, North Carolina.
R P
RP
Gupta
M B
MB
Abou-Donia
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002645:Chickens; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D007531:Isoflurophate / Q000494:pharmacology*; D007700:Kinetics; D010449:Peptide Mapping; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
D007531:Isoflurophate; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium