Properties Of Phosphodiesterase Research Articles

Accumulation du monophosphate cyclique d'adénosine dans l'ovaire d'anguille (Anguilla anguilla L.) in vitro sous l'effet de la gonadotropine de carpe ou de la lutropine ovine : cinétique et thermodépendance

Cyclic AMP (cAMP) in pieces of eel ovary was greatly increased in vitro by the gonadotropin (cGTH) of carp, another teleost fish; after one hour at 20 degrees C, maximal stimulation = 31.7 and E.D. 50 = 0.08 micrograms/ml. Ovine lutropin (oLH) had less effect (maximal stimulation: 2.35; E.D. 50: 1.42 micrograms/ml); its action suggested that it involved a subfraction (oLH/cGTH RAc) of the receptor-adenylate cyclase (RAc) systems which mediate the action of cGTH. Another difference was the percentage of total cAMP accumulated under hormonal stimulation and released into the incubation medium; this percentage was much higher with oLH than with cGTH (47 vs 8% after one hour at 20 degrees C). This result might be explained by a localization of oLH/cGTH RAc in cells (theca ?) situated on the outside of the follicles and/or by a relative lack of cAMP binding proteins in the case of cAMP produced by oLH/cGTH RAc. Kinetic and thermodependence studies also disclosed hormone-dependent differences; at 5 degrees C, cAMP concentration was maximal after 40 min with oLH, whereas it was still increasing after 3 h with cGTH. Differences in the properties of phosphodiesterases and/or in the clearance rate of hormone-receptor (HR) complexes could explain these results. The set of RAc systems in eel ovary recognizing fish gonadotropin would then be heterogeneous; some of them would be endowed with original properties concerning receptor specificity and cAMP diffusion as well as associated phosphodiesterase activity and/or HR metabolism. We suggest that at a stage of evolution when a single sensu stricto GTH is present (instead of two in tetrapods), "isoreceptors", differing in specificity and in their fate after hormone binding, could be an important element in the fine regulation of gonadal functions.

Characteristics of the cyclic nucleotide phosphodiesterases of normal and leukemic lymphocytes.

The specific activity of cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase of leukemic lymphocytes was 5-10-fold greater than that of purified normal lymphocytes or of homogenates of spleen, thymus or lymph nodes of normal mice. This rise was demonstrable over a wide range of substrate concentrations. Both normal and leukemic lymphocytes contained a heat-stable, calcium-dependent activator of phosphodiesterase. However, the increased activity of phosphodiesterase in leukemic lymphocytes was not due to this protein activator since (a) phosphodiesterase activity from these cells was not stimulated by this activator and (b) phosphodiesterase activity of leukemic lymphocytes was not inhibited by the calcium chelater, ethylene-glycol-bis,(beta-aminoethylether)-N,N'-tetraacetic acid, suggesting that the enzyme was not already maximally activated. A comparison of several other properties of phosphodiesterase from normal and leukemic lymphocytes showed that the enzymes have similar pH optima, similar stabilities to freezing and thawing and similar sensitivities to inhibition by the phosphodiesterase inhibitors, chlorpromazine, papaverine and isobutylmethylxanthine. However, the subcellular distribution of the phosphodiesterases was different, and the phosphodiesterase of leukemic lymphocytes was significantly more resistant to heat than that of normal lymphocytes. Although no differences were found between the phosphodiesterases of normal and leukemic lymphocytes in their sensitivities to drugs, there were marked differences in drug sensitivity between the phosphodiesterase of lymphocytes and that of other tissue. For example, concentrations of chlorpromazine which inhibited phosphodiesterase of cerebrum by 70% had no effect on phosphodiesterase activity of lymphocytes. On the othere hand, the papaverine-induced inhibition of phosphodiesterase was similar in lymphocytes and cerebrum. Since an optimal concentration of cyclic nucleotides is essential to maintain normal cell growth, these results suggest that the abnormal growth characteristics of leukemic lymphocytes may be explained by their high activity of phosphodiesterase. Furthermore, the qualitative and quantitiative differences between the phosphodiesterases of leukemic lymphocytes and other tissues raise the possibility of selectively inhibiting the phosphodiesterase of the leukemic lymphocytes, thereby reducing their rate of growth, without affecting other tissues.

Extraction and properties of phosphodiesterase from a forest soil

Phosphodiesterase together with brown-coloured compounds was extracted from a forest soil using 0.1 M phosphate buffer (pH 7). Use of KCl and EDTA with the buffer facilitated phosphodiesterase extraction. Distilled water extracted little enzyme activity. A curvilinear relationship such as the Langmuir type was found between solution volume and phosphodiesterase activity of the extract. The results implied that the phosphodiesterase extracted was extracellular and was adsorbed on the surface of soil particles by ionic bonding. Brown-coloured compounds in the extract were removed by precipitation with protamine sulfate. The phosphodiesterase activity of the extract treated with protamine sulfate was lost on keeping at 80°C for 10 min and was optimal at pH 5.2–6.0. The extract hydrolyzed either the 3'- or the 5'-phosphodiester bond of deoxythymidine p-nitrophenyl phosphate.

Phosphodiesterases in Normal and Dystrophic Human Muscle

SummaryThe levels and some properties of phosphodiesterase I and phosphodi-esterase II were determined in biopsied muscles from normal persons and the results were extended to diseased muscles. The activities of both enzymes were generally normal or minimally elevated in mildly affected muscles from patients with Duchenne dystrophy, other forms of dystrophies and related neuromuscular diseases. However, in severely abnormal muscles, with advanced dystrophy or advanced polymyositis, the levels of these enzymes were greatly elevated.

Some properties of phosphodiesterase I from microsomes of rat intestinal mucosa

Some properties of phosphodiesterase I from microsomes of rat intestinal mucosa were studied using the p-nitrophenyl ester of thymidine 5′-phosphate as substrate. The optimum pH was found to be 9.5–9.6 in several buffer systems. The activity was destroyed at temperatures of 63–68°, depending on the pH of the medium. Mg2+, Ca2+, Sr2+, Ba2+, and Ni2+ had a variable activating effect while Al3+, Cu2+, and Be were inhibitory. The enzyme was inhibited completely by 10−5 M EDTA or EGTA in the assay system used. The evidence obtained suggested phosphodiesterase I is a metal-requiring enzyme. Glycine, bicine, and tricine inhibited the enzyme at higher concentrations. Cysteine, 2-mercaptoethanol, and dithiothreitol were strongly inhibitory at a concentration of 10−3 M. The Km of the enzyme was 8.5 × 10−4 M. In 6 M urea 40% of the activity of the enzyme was lost irreversibly after 24 h at 4°. In 3 M urea there was an immediate and reversible mixed competitive–noncompetitive inhibition and the Km was increased seven to eight times.

Further purification and properties of phosphodiesterase from the carrot.

Further purification and properties of phosphodiesterase from the carrot.

Phosphoesterases of Bacillus subtilis. I. Purification and properties of phosphodiesterases.

Journal Article Phosphoesterases of Bacillus subtilis: I. Purification and Properties of Phosphodiesterases Get access KAZUYA TANIGUCHI, KAZUYA TANIGUCHI From the Laboratory of Molecular Genetics, Medical School, Osaka UniversityOsaka Search for other works by this author on: Oxford Academic PubMed Google Scholar AKIRA TSUGITA AKIRA TSUGITA From the Laboratory of Molecular Genetics, Medical School, Osaka UniversityOsaka Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Biochemistry, Volume 60, Issue 4, October 1966, Pages 372–380, https://doi.org/10.1093/oxfordjournals.jbchem.a128448 Published: 01 October 1966 Article history Received: 15 March 1966 Published: 01 October 1966

Purification and properties of phosphodiesterase from bovine pancreas.

Journal Article Purification and Properties of Phosphodiesterase from Bovine Pancreas Get access TADAO TERAO, TADAO TERAO Faculty of Pharmaceutical Sciences, University of TokyoBunkyo-ku, Tokyo Search for other works by this author on: Oxford Academic PubMed Google Scholar TYUNOSIN UKITA TYUNOSIN UKITA Faculty of Pharmaceutical Sciences, University of TokyoBunkyo-ku, Tokyo Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Biochemistry, Volume 58, Issue 2, August 1965, Pages 153–161, https://doi.org/10.1093/oxfordjournals.jbchem.a128177 Published: 01 August 1965 Article history Received: 31 March 1965 Published: 01 August 1965

Partial Purification and Properties of Phosphodiesterase I from Hog Kidney

Partial Purification and Properties of Phosphodiesterase I from Hog Kidney