title: [Separation and investigation of the regulatory properties of two forms of cyclic nucleotide phosphodiesterase from rabbit heart--sensitive and insensitive to Ca-dependent regulator protein].
abstract: Two forms of cyclic nucleotide phosphodiesterase (ES 3.1.4.17)--PDE-I and PDE-II--sensitive and resistant to Ca-dependent protein regulator, were isolated from the soluble fraction of rabbit heart by chromatography on DEAE-cellulose. Both forms of enzyme are inhibited by 30--50% by Ca2+ (10(-4) M). Addition of Ca-dependent protein regulator activates PDE-I and eliminates Ca2+-induced inhibition of PDE-II. In heart extract Ca2+ increases the phosphodiesterase activity 1.5-fold. The amount of PDE-I makes up to about 10% of total phosphodiesterase activity of the heart; that of PDE-II is about 90%. In the presence of Ca-dependent protein regulator the rate of 3', 5'-AMP hydrolysis by PDE-I is increased 5--15-fold, while that of 3', 5'-GMP hydrolysis only 2.5-fold. Both PDE-I and PDE-II have close Km values for substrates--(3.5--4.0).10(-6) M for 3', 5'-AMP and 14.10(-6) M for 3', 5'-GMP. Inhibition by Ca2+ and effect of Ca-dependent protein regulator manifest themselves in changes in V for cyclic nucleotide hydrolysis and do not alter the Km value for the enzyme.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004789:Enzyme Activation; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology*; D011817:Rabbits
chemical_list: D002147:Calmodulin; D002352:Carrier Proteins; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D002118:Calcium
vernacular_title: Razdelenie i izuchenie reguliatornykh svoistv dvukh form fosfodiesterazy tsiklicheskikh nukleotidov iz serdtsa krolika--chuvsvitel'noi i nechuvstvitel'noi k Ca-zavisimomy belkovomy reguliatoru.