Burns, F and Rodger, I W and Pyne, N J (1992) The catalytic subunit of protein kinase A triggers activation of the type V cyclic GMP-specific phosphodiesterase from guinea-pig lung. Biochemical journal, 283 (2). pp. 487-491. ISSN 0264-6021Full text not available in this repository. (Request a copy from the Strathclyde author)
The type V cyclic GMP phosphodiesterase was partially purified from the high-speed supernatant of guinea-pig lung. The isoenzyme displayed linear kinetics for cyclic GMP hydrolysis, with Km = 2.2 +/- 0.2 microM and Vmax. = 1.2 +/- 0.08 nmol/min per mg. The selective type V phosphodiesterase inhibitor Zaprinast inhibited cyclic GMP hydrolysis with IC50 (concn. giving 50% inhibition) = 0.45 +/- 0.08 microM. Isobutylmethylxanthine promoted a 3-fold increase in the binding of cyclic GMP to the isoenzyme. The addition of the catalytic subunit of protein kinase A to an activation cocktail containing the partially purified type V phosphodiesterase resulted in a marked increase in Vmax. for cyclic GMP hydrolysis (approximately 10-fold at 40 units of protein kinase A). We have suggested that protein kinase A triggers phosphorylation of the phosphodiesterase, which results in activation of phosphodiesterase activity. In addition, the sensitivity to inhibition by Zaprinast is severely decreased (the IC50 for inhibition is 7.5 +/- 1.1 microM), suggesting that the potency of phosphodiesterase inhibitors is effected by phosphorylation of the enzyme.
|Keywords:||3',5'-cyclic-AMP phosphodiesterases, 3',5'-cyclic-GMP phosphodiesterases, animals, chromatography, affinity, chromatography, ion exchange, cytosolic, enzyme activation, guinea pigs, isoenzymes, kinetics, lung, macromolecular substances, protein kinases, purinones, substrate specificity, Pharmacy and materia medica, Biochemistry, Cell Biology, Molecular Biology|
|Subjects:||Medicine > Pharmacy and materia medica|
|Department:||Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences|
|Depositing user:||Pure Administrator|
|Date Deposited:||15 Nov 2011 05:19|
|Last modified:||06 Jan 2017 10:15|