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Proteolysis of cyclic AMP phosphodiesterase-II attenuates its ability to be inhibited by compounds which exert positive inotropic actions in cardiac tissue.
Biochem Pharmacol. 1987 Dec 01; 36(23):4047-54.BP

Abstract

Extraction of frozen canine cardiac muscle rendered soluble over 90% of the cyclic AMP phosphodiesterase activity. The residual activity was membrane-bound. Ion exchange chromatography of the soluble activity on DE-52 allowed for the resolution of three distinct cyclic AMP phosphodiesterase fractions termed PDE-I, PDE-II and PDE-III in order of elution from the column by a linear NaCl gradient. The relative ratio of cyclic AMP phosphodiesterase activity exhibited by these three peaks was 1:0.65:0.82 and of cyclic GMP phosphodiesterase activity was 1:0.52:0.05 for PDE-I, PDE-II and PDE-III respectively. PDE-II and PDE-III were further purified by re-chromatography on DE-52. Fractions PDE-II and PDE-III were thermolabile at 50 degrees, decaying as single exponentials with half lives of 180 sec and 77 sec respectively. All three species exhibited non-linear Lineweaver-Burke plots for the hydrolysis of cyclic AMP, exhibiting both high and low affinity components. Hydrolysis of cyclic GMP by all three components obeyed normal kinetics, yielding linear plots. PDE-I was a Ca2+/calmodulin-activated species which exhibited a low Km for both cyclic AMP and cyclic GMP but hydrolysed cyclic GMP with a higher Vmax than for cyclic AMP. PDE-II exhibited a much lower Km for cyclic AMP than for cyclic GMP and a much higher Vmax for the hydrolysis of cyclic AMP. PDE-III exhibited a low Km for both cyclic AMP and cyclic GMP, however, its Vmax for cyclic AMP was about 40-fold higher than for cyclic GMP. Cyclic GMP acted as a potent inhibitor (IC50 = 6.3 microM) of cyclic AMP hydrolysis catalysed by PDE-III but not of the hydrolysis of cyclic AMP by PDE-II (IC50 = 33.2 microM). The phosphodiesterase inhibitors milrinone, CI-930, UK-35,493, carbazeran and buquineran acted as potent inhibitors of cyclic AMP hydrolysis catalysed by both PDE-II and PDE-III enzymes. They did not inhibit PDE-I activity. PDE-II, when prepared in the absence of protease inhibitors exhibited a reduced potency to inhibition by these compounds. Treatment of purified PDE-II with trypsin caused a reduction in enzyme activity and reduced dramatically the sensitivity of PDE-II activity to inhibition by these various compounds. The action of proteolysis in attenuating the inhibitory effect of these compounds on PDE-II was most dramatic with CI-930, milrinone, amrinone, buquineran and UK35,493 and least dramatic with carbazeran and IBMX.(ABSTRACT TRUNCATED AT 400 WORDS)

Authors+Show Affiliations

Department of Biochemistry, University of Glasgow, Scotland, U.K.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

2825712

Citation

Price, B, et al. "Proteolysis of Cyclic AMP phosphodiesterase-II Attenuates Its Ability to Be Inhibited By Compounds Which Exert Positive Inotropic Actions in Cardiac Tissue." Biochemical Pharmacology, vol. 36, no. 23, 1987, pp. 4047-54.
Price B, Pyne NJ, Houslay MD. Proteolysis of cyclic AMP phosphodiesterase-II attenuates its ability to be inhibited by compounds which exert positive inotropic actions in cardiac tissue. Biochem Pharmacol. 1987;36(23):4047-54.
Price, B., Pyne, N. J., & Houslay, M. D. (1987). Proteolysis of cyclic AMP phosphodiesterase-II attenuates its ability to be inhibited by compounds which exert positive inotropic actions in cardiac tissue. Biochemical Pharmacology, 36(23), 4047-54.
Price B, Pyne NJ, Houslay MD. Proteolysis of Cyclic AMP phosphodiesterase-II Attenuates Its Ability to Be Inhibited By Compounds Which Exert Positive Inotropic Actions in Cardiac Tissue. Biochem Pharmacol. 1987 Dec 1;36(23):4047-54. PubMed PMID: 2825712.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Proteolysis of cyclic AMP phosphodiesterase-II attenuates its ability to be inhibited by compounds which exert positive inotropic actions in cardiac tissue. AU - Price,B, AU - Pyne,N J, AU - Houslay,M D, PY - 1987/12/1/pubmed PY - 1987/12/1/medline PY - 1987/12/1/entrez SP - 4047 EP - 54 JF - Biochemical pharmacology JO - Biochem Pharmacol VL - 36 IS - 23 N2 - Extraction of frozen canine cardiac muscle rendered soluble over 90% of the cyclic AMP phosphodiesterase activity. The residual activity was membrane-bound. Ion exchange chromatography of the soluble activity on DE-52 allowed for the resolution of three distinct cyclic AMP phosphodiesterase fractions termed PDE-I, PDE-II and PDE-III in order of elution from the column by a linear NaCl gradient. The relative ratio of cyclic AMP phosphodiesterase activity exhibited by these three peaks was 1:0.65:0.82 and of cyclic GMP phosphodiesterase activity was 1:0.52:0.05 for PDE-I, PDE-II and PDE-III respectively. PDE-II and PDE-III were further purified by re-chromatography on DE-52. Fractions PDE-II and PDE-III were thermolabile at 50 degrees, decaying as single exponentials with half lives of 180 sec and 77 sec respectively. All three species exhibited non-linear Lineweaver-Burke plots for the hydrolysis of cyclic AMP, exhibiting both high and low affinity components. Hydrolysis of cyclic GMP by all three components obeyed normal kinetics, yielding linear plots. PDE-I was a Ca2+/calmodulin-activated species which exhibited a low Km for both cyclic AMP and cyclic GMP but hydrolysed cyclic GMP with a higher Vmax than for cyclic AMP. PDE-II exhibited a much lower Km for cyclic AMP than for cyclic GMP and a much higher Vmax for the hydrolysis of cyclic AMP. PDE-III exhibited a low Km for both cyclic AMP and cyclic GMP, however, its Vmax for cyclic AMP was about 40-fold higher than for cyclic GMP. Cyclic GMP acted as a potent inhibitor (IC50 = 6.3 microM) of cyclic AMP hydrolysis catalysed by PDE-III but not of the hydrolysis of cyclic AMP by PDE-II (IC50 = 33.2 microM). The phosphodiesterase inhibitors milrinone, CI-930, UK-35,493, carbazeran and buquineran acted as potent inhibitors of cyclic AMP hydrolysis catalysed by both PDE-II and PDE-III enzymes. They did not inhibit PDE-I activity. PDE-II, when prepared in the absence of protease inhibitors exhibited a reduced potency to inhibition by these compounds. Treatment of purified PDE-II with trypsin caused a reduction in enzyme activity and reduced dramatically the sensitivity of PDE-II activity to inhibition by these various compounds. The action of proteolysis in attenuating the inhibitory effect of these compounds on PDE-II was most dramatic with CI-930, milrinone, amrinone, buquineran and UK35,493 and least dramatic with carbazeran and IBMX.(ABSTRACT TRUNCATED AT 400 WORDS) SN - 0006-2952 UR - https://www.unboundmedicine.com/medline/citation/2825712/Proteolysis_of_cyclic_AMP_phosphodiesterase_II_attenuates_its_ability_to_be_inhibited_by_compounds_which_exert_positive_inotropic_actions_in_cardiac_tissue_ DB - PRIME DP - Unbound Medicine ER -