An enzyme preparation from calf intestinal mucosa was studied for phosphodiesterase activity’ but was found to contain also phosphomonoesterase’ and adenosine deaminase.2 Analysis confirmed the presence of polysaccharide, suspected because of solubility in high concentrations of organic solvents and precipitation from aqueous solutions only when fully saturated with ammonium sulfate. Attempts w...

Papaverine, a nonspecific smooth muscle relaxant, is well known to be a potent cyclic AMP phosphodiesterase inhibitor (1, 2). In recent papers (3-8) it has been reported that smooth muscle relaxing action of papaverine is likely to be mediated through an increase of cyclic AMP due to its phosphodiesterase inhibition. Recently attention has drawn to the role of cyclic GMP, which often presents p...

Low concentrations (less than 10 microgram/ml) of a number of highly basic polypeptides inhibit the calmodulin-stimulated cyclic nucleotide phosphodiesterase. Inhibitory compounds include synthetic polypeptides [polylysine (D and L) and polyarginine] and basic proteins (protamine, histones H1, H2A, H2B, H3 and H4 and myelin basic protein). Polylysine of mol.wt. about 2000 or higher was inhibito...

A major concern in attempts to relate the structure of soluble ribonucleic acid with biological specificity is whether an entire molecule of the acid is needed for biological function. Specific monophosphatases and esonucleases offer a tool with which to approach this question. Hydrolysis of S-RNA’ with venom phosphodiesterase (1) destroys the amino acid-accepting ability of S-RNAs (2, 3), pres...

We have isolated and sequenced cDNA clones representing portions of the polyadenylylated transcripts of the dunce+ gene. These define an open reading frame of 1086 bases and some of the 5'- and 3'-untranslated regions of the transcripts. The deduced amino acid sequence is strikingly homologous to the amino acid sequence of a Ca2+/calmodulin-dependent cyclic nucleotide phosphodiesterase isolated...