The catalytic subunit of protein kinase A triggers activation of the type V cyclic GMP-specific phosphodiesterase from guinea-pig lung.

摘要: The type V cyclic GMP phosphodiesterase was partially purified from the high-speed supernatant of guinea-pig lung. isoenzyme displayed linear kinetics for hydrolysis, with Km = 2.2 +/- 0.2 microM and Vmax. 1.2 0.08 nmol/min per mg. selective inhibitor Zaprinast inhibited hydrolysis IC50 (concn. giving 50% inhibition) 0.45 microM. Isobutylmethylxanthine promoted a 3-fold increase in binding to isoenzyme. addition catalytic subunit protein kinase A an activation cocktail containing resulted marked (approximately 10-fold at 40 units A). We have suggested that triggers phosphorylation phosphodiesterase, which results activity. In addition, sensitivity inhibition by is severely decreased (the 7.5 1.1 microM), suggesting potency inhibitors effected enzyme.