Cyclic AMP-dependent ATPase activity of bovine heart protein kinase.
The adenosine 3",5"-monophosphate (cAMP)-dependent ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity of cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) from bovine heart is characterized. That the ATPase activity is intimately associated with the catalytic subunit of the enzyme is suggested by the following: (i) the similar dependences of ATPase and protein kinase activities on cAMP; (ii) the dissociation of ATPase activity from the holoenzyme on addition of cAMP and its co-elution with the catalytic subunit on gel filtration chromatography; (iii) the similarity of the relative effectiveness of divalent metal ions in ATPase and protein kinase catalysis; and (iv) the correspondence of kinetically determined Km(MgATP) and Ki(MgADP) values with thermodynamic dissociation constants determined by equilibrium dialysis. The hydrolysis of ATP is stimulated 10- to 20-fold by cAMP in the holoenzyme. The molar specific activity of the catalytic subunit ATPase is approximately 0.7 min-1 with Km(MgATP) = 5 muM. MgADP is a competitive inhibitor of the reaction with a Ki value of approximately muM. The order of the relative effectiveness of metal ions for both ATPase and peptide kinase activities is Mg2+ greater than Mn2+ greater than Ca2+. A possible interpretation of these observations is that the role that the metal ion plays is more directly manifested in bond-breaking than in bond-forming.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002384:Catalysis; D002413:Cations, Divalent / Q000494:pharmacology; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D009206:Myocardium / Q000201:enzymology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D013816:Thermodynamics
D002413:Cations, Divalent; D046911:Macromolecular Substances; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D011494:Protein Kinases; D000251:Adenosine Triphosphatases