title: Purification of phosphoprotein phosphatase from bovine cardiac muscle that catalyzes dephosphorylation of cyclic AMP-binding protein component of protein kinase.
abstract: A phosphoprotein phosphatase that catalyzes the dephosphorylation of cyclic adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase from bovine cardiac muscle has been purified to homogeneity by a modification of the procedure of Brandt et al. (Brandt, H., Capulong, Z.L., and Lee, E. Y. C. (1975) J. Biol. Chem. 250, 8038-8044). Treatment of the enzyme preparation with ethanol during the early stages of purification results in activation concomitant with reduction in molecular weight to 30,000. The purified activated enzyme has a Km for phospho-protein kinase in the presence or absence of 1.2 mM Mn2+ of 5 and 22 micronM, respectively. Phosphatase activity on phospho-protein kinase but not on other phosphoprotein substrates was cAMP-dependent. This selective activation by cAMP reflects the preference of the phosphatase for the free, phosphorylated cAMP-binding protein rather than the phosphoholoenzyme.
mesh_terms: D000818:Animals; D002417:Cattle; D000242:Cyclic AMP / Q000494:pharmacology; D004789:Enzyme Activation; D007700:Kinetics; D046911:Macromolecular Substances; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D009206:Myocardium / Q000201:enzymology*; D010750:Phosphoproteins; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification* / Q000378:metabolism; D011494:Protein Kinases; D011953:Receptors, Cyclic AMP / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D046911:Macromolecular Substances; D010750:Phosphoproteins; D011953:Receptors, Cyclic AMP; D008345:Manganese; D000242:Cyclic AMP; D011494:Protein Kinases; D010744:Phosphoric Monoester Hydrolases