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Schneider EH, Seifert R. Inactivation of Non-canonical Cyclic Nucleotides: Hydrolysis and Transport. Handb Exp Pharmacol 2017; 238:169-205. [PMID: 28204955 DOI: 10.1007/164_2016_5004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This chapter addresses cNMP hydrolysis by phosphodiesterases (PDEs) and export by multidrug resistance associated proteins (MRPs). Both mechanisms are well-established for the canonical cNMPs, cAMP, and cGMP. Increasing evidence shows that non-canonical cNMPs (specifically cCMP, cUMP) are also PDE and MRP substrates. Hydrolysis of cUMP is achieved by PDE 3A, 3B, and 9A, which possibly explains the cUMP-degrading activities previously reported for heart, adipose tissue, and brain. Regarding cCMP, the only known "conventional" (class I) PDE that hydrolyzes cCMP is PDE7A. Older reports describe cCMP-degrading PDE-like activities in mammalian tissues, bacteria, and plants, but the molecular identity of these enzymes is not clear. High K M and V max values, insensitivity to common inhibitors, and unusually broad substrate specificities indicate that these activities probably do not represent class I PDEs. Moreover, the older results have to be interpreted with caution, since the historical analytical methods were not as reliable as modern highly sensitive and specific techniques like HPLC-MS/MS. Besides PDEs, the transporters MRP4 and 5 are of major importance for cAMP and cGMP disposal. Additionally, both MRPs also export cUMP, while cCMP is only exported by MRP5. Much less data are available for the non-canonical cNMPs, cIMP, cXMP, and cTMP. None of these cNMPs has been examined as MRP substrate. It was shown, however, that they are hydrolyzed by several conventional class I PDEs. Finally, this chapter reveals that there are still large gaps in our knowledge about PDE and MRP activities for canonical and non-canonical cNMPs. Future research should perform a comprehensive characterization of the known PDEs and MRPs with the physiologically most important cNMP substrates.
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Affiliation(s)
- Erich H Schneider
- Institute of Pharmacology, Medical School of Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Roland Seifert
- Institute of Pharmacology, Medical School of Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
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Sharma S, Visweswariah SS. Illuminating Cyclic Nucleotides: Sensors for cAMP and cGMP and Their Application in Live Cell Imaging. J Indian Inst Sci 2017. [DOI: 10.1007/s41745-016-0014-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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3
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Seifert R, Schneider EH, Bähre H. From canonical to non-canonical cyclic nucleotides as second messengers: pharmacological implications. Pharmacol Ther 2014; 148:154-84. [PMID: 25527911 DOI: 10.1016/j.pharmthera.2014.12.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 12/11/2014] [Indexed: 02/07/2023]
Abstract
This review summarizes our knowledge on the non-canonical cyclic nucleotides cCMP, cUMP, cIMP, cXMP and cTMP. We place the field into a historic context and discuss unresolved questions and future directions of research. We discuss the implications of non-canonical cyclic nucleotides for experimental and clinical pharmacology, focusing on bacterial infections, cardiovascular and neuropsychiatric disorders and reproduction medicine. The canonical cyclic purine nucleotides cAMP and cGMP fulfill the criteria of second messengers. (i) cAMP and cGMP are synthesized by specific generators, i.e. adenylyl and guanylyl cyclases, respectively. (ii) cAMP and cGMP activate specific effector proteins, e.g. protein kinases. (iii) cAMP and cGMP exert specific biological effects. (iv) The biological effects of cAMP and cGMP are terminated by phosphodiesterases and export. The effects of cAMP and cGMP are mimicked by (v) membrane-permeable cyclic nucleotide analogs and (vi) bacterial toxins. For decades, the existence and relevance of cCMP and cUMP have been controversial. Modern mass-spectrometric methods have unequivocally demonstrated the existence of cCMP and cUMP in mammalian cells. For both, cCMP and cUMP, the criteria for second messenger molecules are now fulfilled as well. There are specific patterns by which nucleotidyl cyclases generate cNMPs and how they are degraded and exported, resulting in unique cNMP signatures in biological systems. cNMP signaling systems, specifically at the level of soluble guanylyl cyclase, soluble adenylyl cyclase and ExoY from Pseudomonas aeruginosa are more promiscuous than previously appreciated. cUMP and cCMP are evolutionary new molecules, probably reflecting an adaption to signaling requirements in higher organisms.
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Affiliation(s)
- Roland Seifert
- Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany.
| | - Erich H Schneider
- Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany
| | - Heike Bähre
- Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany
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PDE7A1 hydrolyzes cCMP. FEBS Lett 2014; 588:3469-74. [PMID: 25128584 DOI: 10.1016/j.febslet.2014.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 08/02/2014] [Accepted: 08/04/2014] [Indexed: 12/27/2022]
Abstract
The degradation and biological role of the cyclic pyrimidine nucleotide cCMP is largely elusive. We investigated nucleoside 3',5'-cyclic monophosphate (cNMP) specificity of six different recombinant phosphodiesterases (PDEs) by using a highly-sensitive HPLC-MS/MS detection method. PDE7A1 was the only enzyme that hydrolyzed significant amounts of cCMP. Enzyme kinetic studies using purified GST-tagged truncated PDE7A1 revealed a cCMP KM value of 135 ± 19 μM. The Vmax for cCMP hydrolysis reached 745 ± 27 nmol/(minmg), which is about 6-fold higher than the corresponding velocity for adenosine 3',5'-cyclic monophosphate (cAMP) degradation. In summary, PDE7A is a high-speed and low-affinity PDE for cCMP.
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Schneider E, Kuhn M, Reinecke D, Wolter S, Burhenne H, Kaever V, Seifert R. Fishing for elusive cCMP-degrading phosphodiesterases. BMC Pharmacol Toxicol 2013. [PMCID: PMC3765655 DOI: 10.1186/2050-6511-14-s1-p62] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Seifert R, Beste K, Burhenne H, Voigt U, Wolter S, Hammerschmidt A, Reinecke D, Sandner P, Pich A, Schwede F, Genieser HG, Kaever V. Cyclic CMP and cyclic UMP: new (old) second messengers. BMC Pharmacol 2011. [PMCID: PMC3363193 DOI: 10.1186/1471-2210-11-s1-o34] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Abstract
The natural occurrence of cyclic nucleotides in higher plants, formerly a topic of fierce debate, is now established, as is the presence of nucleotidyl cyclases and cyclic nucleotide phosphodiesterases capable of their synthesis and breakdown. Here we describe the significant properties of cyclic nucleotides, also outlining their second messenger functions and the history of plant cyclic nucleotide research over its first three decades. Findings of the last five years are detailed within the context of the functional role of cyclic nucleotides in higher plants, with particular emphasis upon nucleotidyl cyclases and cyclic nucleotide-responsive protein kinases, -binding proteins and -gated ion channels, with future objectives and strategies discussed.
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Affiliation(s)
- Russell P Newton
- Biochemistry Group, School of Biological Sciences, Wallace Building, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK.
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Mendel DB, Cihlar T, Moon K, Chen MS. Conversion of 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosine to cidofovir by an intracellular cyclic CMP phosphodiesterase. Antimicrob Agents Chemother 1997; 41:641-6. [PMID: 9056007 PMCID: PMC163765 DOI: 10.1128/aac.41.3.641] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cidofovir (HPMPC) [1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]-cytosine] is an acyclic nucleotide analog with potent and selective activity against herpesviruses. The prodrug, cyclic HPMPC (cHPMPC) [1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl) methyl]cytosine], has antiviral activity similar to that of the parent compound but exhibits reduced toxicity in animal models. cHPMPC is converted to cidofovir by a cellular cyclic CMP phosphodiesterase (EC 3.1.4.37) which hydrolyzes a variety of substrates, including adenosine 3',5'-cyclic monophosphate (cAMP) and cytidine 3',5'-cyclic monophosphate (cCMP). The K(m) and Vmax values for hydrolysis of cHPMPC by cCMP phosphodiesterase purified from human liver are 250 microM and 0.66 nmol.min-1.unit-1, respectively. These values are similar to the K(m) and Vmax values for cAMP (23 microM and 1.16 nmol.min-1.unit-1, respectively) and cCMP (75 microM and 2.32 nmol.min-1.unit of enzyme-1, respectively). The catalytic efficiency (Vmax/K(m) ratio) of this enzyme for the cHPMPC substrate is only 10- to 20-fold lower than those for the natural cyclic nucleotides, indicating that cHPMPC is a viable intracellular substrate for the human enzyme. Kinetic analysis indicates that cHPMPC, cAMP, and cCMP are competitive with respect to each other and that they are hydrolyzed by the same enzyme. cHPMPC is hydrolyzed to cidofovir in all primary human cell systems tested, including those derived from target organs that might be infected in patients with human cytomegalovirus (HCMV) disease. Importantly, hydrolysis of cHPMPC is not diminished in cells infected with HCMV.
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Affiliation(s)
- D B Mendel
- Gilead Sciences, Inc., Foster City, California 94404, USA.
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9
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Newton RP, Evans AM, van Geyschem J, Diffley PJ, Hassam HG, Hakeem NA, Moyse CD, Cooke R, Salvage BJ. Radioimmunoassay of cytidine 3',5'-cyclic monophosphate: unambiguous assay by means of an optimized protocol incorporating a trilayer column separation to obviate cross-reactivity problems. JOURNAL OF IMMUNOASSAY 1994; 15:317-37. [PMID: 7836541 DOI: 10.1080/15321819408009581] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previous assays for cytidine 3', 5'-cyclic monophosphate (cyclic CMP) have been criticized as being ambiguous. Here a modified RIA protocol, in which the production of assay components has been optimized and a novel trilayer chromatography column separation introduced which successfully separates cyclic CMP from compounds, endogenous to living tissues, which cross-react with anti-cyclic CMP sera, is described. The assay is capable of assaying cyclic CMP between 0.1 and 5 pmol, can be increased in sensitivity by means of an additional acetylation step, and enables the separation of cyclic CMP, cyclic AMP and cyclic GMP so that all three can be estimated in a single sample.
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Affiliation(s)
- R P Newton
- Biochemistry Group, School of Biological Sciences, University College Swansea, United Kingdom
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Worby A, Mensah LM, Murray KJ. Identification of the novel rat liver IBMX-insensitive phosphodiesterase as a non-specific phosphodiesterase capable of hydrolysing cCMP. Biochem Pharmacol 1991; 42:1318-21. [PMID: 1716099 DOI: 10.1016/0006-2952(91)90274-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- A Worby
- SmithKline Beecham Pharmaceuticals, Welwyn, Herts, U.K
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Newton RP, Khan JA, Ghosh D, Langridge JI, Brenton AG, Harris FM, Walton TJ. Determination of enzyme kinetic parameters of cyclic CMP-specific phosphodiesterase by quantitative fast atom bombardment tandem mass spectrometry. ACTA ACUST UNITED AC 1991. [DOI: 10.1002/oms.1210260514] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Newton RP, Salih SG. Cyclic CMP phosphodiesterase: isolation, specificity and kinetic properties. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1986; 18:743-52. [PMID: 3017781 DOI: 10.1016/0020-711x(86)90398-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cyclic CMP phosphodiesterase activity was demonstrated in rat liver, heart, brain, kidney, intestine, skeletal muscle, blood, testes, ovaries, spleen and lung; that present in the liver was purified to homogeneity by a sequential process of ammonium sulphate fractionation, gel filtration, two ion-exchange chromatographic steps, preparative electrophoresis and two affinity chromatographic stages with selection at each stage for maximum specificity. The final enzyme preparation was confirmed as a single protein by HPLC and isoelectric focussing; the total yield obtained was 1.5% and the final specific activity of 48.6 mumol cyclic CMP hydrolysed/min/mg reflected a 88,000 fold purification. The phosphodiesterase had a Mr of 2.8 X 10(4), pH optimum 7.2-7.4, isoelectric point between 4.2 and 4.4 and a Km of 9.0 mM cyclic CMP. This enzyme differs from a previously isolated cyclic CMP phosphodiesterase in its amino acid composition and specificity. The absolute specificity for 3',5'-cyclic CMP as substrate distinguishes this cyclic CMP phosphodiesterase from all other reported phosphodiesterases and shows it to be a novel enzyme. Its potential as a research tool and the significance of its occurrence are discussed.
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Suoranta K, Londesborough J. Purification of intact and nicked forms of a zinc-containing, Mg2+-dependent, low Km cyclic AMP phosphodiesterase from bakers' yeast. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)39823-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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14
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Abstract
The cellular concentration of cyclic nucleotides is largely dependent upon the activity of the enzymatic system responsible for their degradation: cyclic nucleotide phosphodiesterase. This enzymatic system thus plays a crucial role in the regulation of the multiple functions which are modulated by cyclic nucleotides in the organism. Many methodological problems, as well as the complexity of the phosphodiesterase system have long maintained a confusion in this field. Recent progresses (purification to homogeneity of some enzymatic forms, discovery of regulatory mechanisms, particularly) have brought a considerable evolution in the knowledge of the system. It is now well established that cyclic nucleotide phosphodiesterase exists under several isoenzymatic forms, the properties and distribution of which largely differ from a tissue to another. Some of these forms are relatively well characterized, while the representativity of others is still discussed. The significance of this multiplicity of isoenzymes, and their interrelationships are presently under study. A very interesting aspect in the study of this enzymatic system is that it is submitted to several physiological regulatory processes. Recent studies on this point suggest that phosphodiesterase might play a major role in the response of the organism to several hormones. These fundamental studies of phosphodiesterase system find a most interesting application in the pharmacological field. Indeed, numerous synthetic compounds which inhibit the enzyme present a strong pharmacological interest.
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Yamamoto T, Manganiello VC, Vaughan M. Purification and characterization of cyclic GMP-stimulated cyclic nucleotide phosphodiesterase from calf liver. Effects of divalent cations on activity. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44208-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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16
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Wei JW, Hickie RA. Decreased activities of cyclic cytidine 3',5'-monophosphate phosphodiesterase in Morris hepatomas having varying growth rates. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1983; 15:789-95. [PMID: 6305741 DOI: 10.1016/0020-711x(83)90151-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. The activities of cyclic cytidine 3',5'-monophosphate (cCMP) phosphodiesterase in normal rat liver and host liver (bearing hepatoma 5123 t.c.(h)) were compared with those of three Morris hepatomas of varying growth rates. 2. The results show that the order of enzyme activity was as follows: normal liver = host liver greater than 7794A (slow growth rate) greater than 5123 t.c.(h) (intermediate growth rate) greater than 7800 (fast growth rate). 3. The enzyme had a pH optimal value of about 7.0 and an apparent Km for cCMP about 2.8 mM; its activity was slightly affected by the presence of calmodulin (100 micrograms/ml) and/or CaCl2 (100 microM), but showed variable responses to other cations (La3+, Mg2+, Mn2+, Zn2+, Fe2+, Na+ and K+).
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Beavo JA, Hansen RS, Harrison SA, Hurwitz RL, Martins TJ, Mumby MC. Identification and properties of cyclic nucleotide phosphodiesterases. Mol Cell Endocrinol 1982; 28:387-410. [PMID: 6185373 DOI: 10.1016/0303-7207(82)90135-6] [Citation(s) in RCA: 123] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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18
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Turner RS, Chou CH, Kibler RF, Kuo JF. Basic protein in brain myelin is phosphorylated by endogenous phospholipid-sensitive Ca2+-dependent protein kinase. J Neurochem 1982; 39:1397-404. [PMID: 6181205 DOI: 10.1111/j.1471-4159.1982.tb12583.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Phosphorylation of myelin basic protein (MBP) in rat or rabbit brain myelin was markedly stimulated by Ca2+, and this reaction was not essentially augmented by exogenous phosphatidylserine or calmodulin or both. Solubilization of myelin with 0.4% Triton X-100 plus 4 mM EGTA, with or without further fractionation, showed that Ca2+-dependent phosphorylation of MBP required phosphatidylserine, but not calmodulin. DEAE-cellulose chromatography of solubilized myelin revealed a pronounced peak of protein kinase activity stimulated by a combination of Ca2+ and phosphatidylserine; a protein kinase stimulated by Ca2+ plus calmodulin was not detected. These findings clearly indicate an involvement of phospholipid-sensitive Ca2+-dependent protein kinase in phosphorylation of brain MBP, although a possible role for the calmodulin-sensitive species of Ca2+-dependent protein kinase in this reaction could not be excluded or established. Phosphorylation of MBP in solubilized rat myelin catalyzed by the phospholipid-sensitive enzyme was inhibited by adriamycin, palmitoylcarnitine, trifluoperazine, melittin, polymyxin B, and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7).
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Epstein PM, Strada SJ, Sarada K, Thompson WJ. Catalytic and kinetic properties of purified high-affinity cyclic AMP phosphodiesterase from dog kidney. Arch Biochem Biophys 1982; 218:119-33. [PMID: 6293381 DOI: 10.1016/0003-9861(82)90327-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Sato T, Kuninaka A, Yoshino H. A practically sensitive radioimmunoassay for cyclic CMP by 2'-O-acetylation. Anal Biochem 1982; 123:208-18. [PMID: 6287882 DOI: 10.1016/0003-2697(82)90646-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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22
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Regulation of cyclic adenosine 3':5'-monophosphate phosphodiesterases. Interrelationship of the various forms in rat skeletal myoblasts and adult muscle. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34769-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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23
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Helfman DM, Kuo JF. Differential effects of various phosphodiesterase inhibitors, pyrimidine and purine compounds, and inorganic phosphates on cyclic CMP, cyclic AMP and cyclic GMP phosphodiesterases. Biochem Pharmacol 1982; 31:43-7. [PMID: 6277336 DOI: 10.1016/0006-2952(82)90233-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effects of various compounds on homogeneous cyclic CMP phosphodiesterase (cyclic CMP-PDE) from pig liver were compared with the effects on cyclic AMP phosphodiesterase (cyclic AMP-PDE) and cyclic GMP phosphodiesterase (cyclic GMP-PDE). Of the conventional inhibitors for AMP-PDE and cyclic GMP-PDE, only Sch 15280 was found to inhibit cyclic CMP-PDE. Nucleoside monophosphates, orthophosphate, and 2':3'-cyclic nucleotides were rather specific and were more effective in inhibiting cyclic CMP-PDE, compared to their effects on cyclic AMP-PDE and cyclic GMP-PDE. On the other hand, nucleoside di-and triphosphates and pyrophosphate (PPi) were less effective in inhibiting cyclic CMP-PDE and were without marked effect on cyclic AMP-PDE and cyclic GMP-PDE. Orthophosphate (Pi) was more potent than CMP, CDP and CTP in inhibiting cyclic CMP-PDE, with a rank order of inhibitory potency of Pi greater than CMP greater than CDP greater than CTP. Of the 3' :5'-cyclic nucleotides examined, cyclic UMP was more specific in inhibiting cyclic CMP-PDE compared to its effect on cyclic AMP-PDE and cyclic GMP-PDE. In all experiments similar results were obtained when either cyclic CMP or cyclic AMP was used as a substrate for this multifunctional cyclic CMP-PDE, supporting the contention that a single catalytic site on the enzyme is responsible for the hydrolysis of both cyclic CMP and cyclic AMP. The present studies further support our original suggestion that cyclic CMP-PDE is a unique enzyme that is distinguishable from the conventional enzymes for purine cyclic nucleotides.
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Helfman D, Kuo J. A homogeneous cyclic CMP phosphodiesterase hydrolyzes both pyrimidine and purine cyclic 2':3'- and 3':5'-nucleotides. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(19)68305-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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25
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Regulation of three forms of cytochrome P-450 and epoxide hydrolase in rat liver microsomes. Effects of age, sex, and induction. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)70085-4] [Citation(s) in RCA: 257] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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