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1

Analogs of diadenosine tetraphosphate [Ap4A]

100%
Guranowski A.
Acta Biochimica Polonica
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2003
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tom 50
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nr 4
This review summarizes our knowledge of analogs and derivatives of diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A), the most extensively studied member of the dinucleoside 5',5"'-P1,Pn-polyphosphate (NpnN) family. After a short discussion of enzymes that may be responsible for the accumulation and degradation of Np4N's in the cell, this review focuses on chemically and/or enzymatically produced analogs and their practical applications. Particular attention is paid to compounds that have aided the study of enzymes involved in the metabolism of Ap4A (Np4N'). Certain Ap4A analogs were alternative substrates of Ap4A-degrading enzymes and/or acted as enzyme inhibitors, some other helped to establish enzyme mechanisms, increased the sensitivity of certain enzyme assays or produced stable enzyme:ligand complexes for structural analysis.
2
Content available remote

Renal haemodynamics and natriuretic responses to intravenous administration of diadenosine tetraphosphate [AP4A] and nicotinamide adenine dinucleotide [NAD] in rat

75%
Szczepanska-Konkel M., Langner G., Bednarczuk G., Stiepanow-Trzeciak A., Jankowski M., Angielski S.
Journal of Physiology and Pharmacology
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2003
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tom 54
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nr 2
Effects of Ap4A and NAD - precursor of adenosine, on renal plasma flow (RPF), glomerular filtration rate (GFR) and urine excretion were determined in the anaesthetised rats. Infusion of Ap4A or NAD (i.v., bolus - 1 µmol/kg followed by 10 nmol/min/kg) decreased RPF and GFR (by 30 and 40%, respectively). In spite of GFR reduction during Ap4A infusion, the significant increase in sodium excretion and urine flow was noticed: fractional sodium (FENa) and urine excretion (FEurine) rose 15-fold and 2.5-fold in comparision with the control value, respectively. In contrast to Ap4A, NAD-induced decrease in GFR was associated with parallel decrease in sodium and urine excretion, thus the FENa and FEurine did not significantly change. Pre-treatment with adenosine deaminase (adenosine degrading enzyme, 2 U/min/kg) or theophylline (P1-receptors antagonist, 0.2 mmol/min/kg) ceased responses to NAD, wherease Ap4A-induced changes were not affected. Pre-treatment with suramin (P2-receptors antagonist, (i.v., bolus - 12 mg/kg followed by 1.2 mg/min/kg) completely abolished the renal effects of Ap4A. We conclude that Ap4A may exert specific action on renal function. It acts different from NAD that modified renal function through its hydrolysis product - adenosine. Ap4A might reduce glomerular filtration rate and evoke natriuresis and diuresis, and its effects are probably mediated through stimulation of P2-receptors.
3
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Dissociation between the effects of P1,P4-diadenosine tetraphosphate (Ap4A) on renal haemodynamics and tubular function in anaesthetized rats

63%
Jankowski M., Angielski S., Szczepanska-Konkel M.
Journal of Physiology and Pharmacology
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2008
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tom 59
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nr 1
Previous studies from our laboratory have reported a marked reduction in glomerular filtration rate (GFR) and sodium reabsorption in renal proximal tubule during intravenous infusion of P1,P4-diadenosine tetraphosphate (Ap4A) at dose of 1.0 µmol/kg + 10 nmol/kg/min (i.v., injection followed by infusion) in anaesthetized Wistar rats. In the present study, the changes of GFR and urine sodium excretion were investigated in response to systemic infusion of Ap4A at different doses. Ap4A at dose of 0.1 µmol/kg + 1.0 nmol/kg/min did not change GFR and sodium urinary excretion whereas 2-fold higher dose produced significant (3.4-fold) increase in sodium excretion without changes in GFR. Significant but transient reduction in GFR by ~21% was observed during infusion of Ap4A at dose of 0.5 µmol/kg + 5.0 nmol/kg/min. Higher doses of Ap4A (1.0 µmol/kg + 10 nmol/kg/min and 2.0 µmol/kg + 20 nmol/kg/min) produced sustained reduction in GFR and marked natriuresis. Our results suggest that tubular sodium transport systems are more sensitive to Ap4A than systems involved in GFR regulation.
4

Selective splitting of 3'-adenylated dinucleoside polyphosphates by specific enzymes degrading dinucleoside polyphosphates

63%
Guranowski A., Sillero A., Gunther-Sillero M. A.
Acta Biochimica Polonica
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2003
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tom 50
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nr 1
Several 3' -[32 P]adenylated dinucleoside polyphosphates (NpnN' p*As) were synthe­sized by the use of poly(A) polymerase (Sillero MAG etal., 2001, Eur JBiochem.; 268: 3605-11) and three of them, ApppA[ 32P]A or ApppAp*A, AppppAp*A and GppppGp*A, were tested as potential substrates of different dinucleoside polyphosphate degrading enzymes. Human (asymmetrical) dinucleoside tetraphosphatase (EC 3.6.1.17) acted almost randomly on both AppppAp*A, yielding approximately equal amounts of pppA + pAp*A and pA + pppAp*A, and GppppGp*, yielding pppG + pGp*A and pG + pppGp*A. Narrow-leafed lupin (Lupinus angustifolius) tetraphosphatase acted preferentially on the dinucleotide unmodified end of both AppppAp*A (yielding 90% of pppA + pAp*A and 10 % of pA + pppAp*A) and GppppGp*A (yielding 89% pppG + pGp*A and 11% of pG + pppGp*A). (Symmetri­cal) dinucleoside tetraphosphatase (EC 3.6.1.41) from Escherichia coli hydrolyzed AppppAp*A and GppppGp*A producing equal amounts of ppA + ppAp*A| and ppG + ppGp*A, respectively, and, to a lesser extent, ApppAp*A producing pA + ppAp*A. Two dinucleoside triphosphatases (EC 3.6.1.29) (the human Fhit protein and the enzyme from yellow lupin (Lupinus luteus)) and dinucleoside tetraphosphate phosphorylase (EC 2.7.7.53) from Saccharomyces cerevisiae did not degrade the three 3 -adenylated dinucleoside polyphosphates tested.
5

Methanetrisphosphonate and its adenine nucleotide derivatives as inhibitors of human and plant diadenosine tetraphosphate hydrolases

51%
Maksel D., Gayler K., Liu X., Blackburn M., McLennan A. G., Guranowski A.
Cellular and Molecular Biology Letters
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1999
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tom 04
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nr 3
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