title: Cyclic AMP phosphodiesterase activities in Xenopus laevis oocytes.
abstract: Cyclic AMP phosphodiesterase activity has been identified in full-grown Xenopus oocytes in vivo and in vitro. About 50% of the in vitro phosphodiesterase activity was present in the solution fraction and 35% in a partially purified membrane fraction. Both activities exhibited high substrate affinity (Km about 10(-6) M). Sucrose gradient fractionation revealed two forms of phosphodiesterase: a 5 S form (peak I) and a 6.5 S form (peak II). Treatment with trypsin led to the activation of the soluble enzyme with the transformation of peak II into peak I. Ethylene glycol bis (beta-aminoethyl ether)-N,N'-tetraacetic acid, calcium dependent regulator, and Fluphenazine did not influence the enzyme activities suggesting that the oocyte phosphodiesterases were not Ca2+-dependent. Intact oocytes were induced to mature by exposure to progesterone; their phosphodiesterase activities and distribution tested in vitro were comparable to those of untreated oocytes.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D002147:Calmodulin / Q000494:pharmacology; D002458:Cell Fractionation / Q000379:methods; D002462:Cell Membrane / Q000201:enzymology; D000242:Cyclic AMP; D003600:Cytosol / Q000201:enzymology; D005026:Ethylene Glycols / Q000494:pharmacology; D005260:Female; D005476:Fluphenazine / Q000494:pharmacology; D009865:Oocytes / Q000201:enzymology*; D010063:Ovum / Q000201:enzymology*; D011374:Progesterone / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology; D014981:Xenopus / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D005026:Ethylene Glycols; D011374:Progesterone; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D014357:Trypsin; D005476:Fluphenazine