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Cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase activities of rat mammary tissue.

ABSTRACT: Cyclic nucleotide phosphodiesterase activity in mammary tissue from rats in midlactation was resolved by DEAE-cellulose chromatography into three functionally distinct fractions: a Ca2+/calmodulin-stimulated cyclic GMP phosphodiesterase, a cyclic GMP-stimulated low-affinity cyclic nucleotide phosphodiesterase, and a high-affinity cyclic AMP-specific phosphodiesterase. The absolute activities and relative proportions of high- and low-affinity enzymes resemble those found, for example, in liver, as distinct from those in excitable tissues. Three functional characteristics are described which are peculiar to mammary-tissue phosphodiesterases. Firstly, the concentration of free Ca2+ required to achieve half-maximal activation of the Ca2+/calmodulin-stimulated phosphodiesterase is somewhat higher than for the analogous enzyme in other tissues; secondly, the activity of this enzyme towards cyclic AMP relative to that towards cyclic GMP is unusually low, and thirdly, the low-affinity cyclic nucleotide phosphodiesterase is inhibited by low concentrations of free Ca2+.

SUBMITTER: Mullaney I

PROVIDER: S-EPMC1153547 | biostudies-other | 1984 May

REPOSITORIES: biostudies-other

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The metabolism of cyclic nucleotides in the guinea-pig pancreas. Cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase.

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| S-EPMC1161601 | biostudies-other

Distinct allostery induced in the cyclic GMP-binding, cyclic GMP-specific phosphodiesterase (PDE5) by cyclic GMP, sildenafil, and metal ions.

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| S-EPMC2566190 | biostudies-literature

Bacterial cyclic AMP-phosphodiesterase activity coordinates biofilm formation.

Project description:Biofilm-related infections are a major contributor to human disease, and the capacity for surface attachment and biofilm formation are key attributes for the pathogenesis of microbes. Serratia marcescens type I fimbriae-dependent biofilms are coordinated by the adenylate cyclase, CyaA, and the cyclic 3',5'-adenosine monophosphate (cAMP)-cAMP receptor protein (CRP) complex. This study uses S. marcescens as a model system to test the role of cAMP-phosphodiesterase activity in controlling biofilm formation. Herein we describe the characterization of a putative S. marcescens cAMP-phosphodiesterase gene (SMA3506), designated as cpdS, and demonstrated to be a functional cAMP-phosphodiesterase both in vitro and in vivo. Deletion of cpdS resulted in defective biofilm formation and reduced type I fimbriae production, whereas multicopy expression of cpdS conferred a type I fimbriae-dependent hyper-biofilm. Together, these results support a model in which bacterial cAMP-phosphodiesterase activity modulates biofilm formation.

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Identification and characterization of both the cytosolic and particulate forms of cyclic GMP-stimulated cyclic AMP phosphodiesterase from rat liver.

Project description:Two enzymes displaying cyclic GMP-stimulated cyclic AMP phosphodiesterase activity were purified from rat liver to apparent homogeneity: a 'particulate enzyme' found as an integral membrane protein associated with the plasma membrane, and a 'soluble' enzyme found in the cytosol. The physical properties of these enzymes were very similar, being dimers of Mr 134,000, composed in each instance of two subunits of Mr = 66,000-67,000. Both enzymes showed similar kinetics for cyclic AMP hydrolysis. They are both high-affinity enzymes, with kinetic constants for the particulate enzyme of Km = 34 microM and Vmax. = 4.0 units/mg of protein and for the cytosolic enzyme Km = 40 microM and Vmax. = 4.8 units/mg of protein. In both instances hydrolysis of cyclic AMP appeared to show apparent positive co-operativity, with Hill coefficients (happ.) of 1.5 and 1.6 for the particulate and cytosolic enzymes respectively. However, in the presence of 2 microM-cyclic GMP, the hydrolysis of cyclic AMP obeyed Michaelis kinetics (happ. = 1) for both enzymes. The addition of micromolar concentrations of cyclic GMP had little effect on the Vmax. for cyclic AMP hydrolysis, but lowered the Km for cyclic AMP hydrolysis to around 20 microM in both cases. However, at low cyclic AMP substrate concentrations, cyclic GMP was a more potent activator of the particulate enzyme than was the soluble enzyme. The activity of these enzymes could be selectively inhibited by cis-16-palmitoleic acid and by arachidonic acid. In each instance, however, the hydrolysis of cyclic AMP became markedly more sensitive to such inhibition when low concentrations of cyclic GMP were present. Tryptic peptide maps of iodinated preparations of these two purified enzyme species showed that there was considerable homology between these two enzyme forms.

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| S-EPMC3775879 | biostudies-literature

Cyclic GMP-specific phosphodiesterase-5 regulates motility of sea urchin spermatozoa.

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| S-EPMC1345651 | biostudies-literature

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