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Results for “ADENINE NUCLEOTIDES”

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At least 19 recordsLinked to original sources
PubMed1979

Effect of cholesterol-rich diet on the content of nicotinamide nucleotides, adenine nucleotides and acetyl-CoA in the liver, the vascular wall and the kidney of spontaneously hypertensive rats (SHR).

The liver content of NAD and of adenylic nucleotides of normally fed spontaneously hypertensive rats (SHR) is lower than in normotensive rats. The cholesterol-rich diet does not change the liver NAD level. However it decreases adenine nucleotides and increases the level of acetyl-CoA and of NADP. Normal refeeding after a long-term cholesterol-rich diet induces an increase in the low levels of the coenzymes (moth NAD and adenine nucleotides). The liver coenzyme changes caused by the cholesterol-rich diet and by the normal refeeding of SHR are opposite to those established in normotensive rats. Vascular wall nicotinamide coenzymes in SHR are lower than in ulistar rats. The vascular wall of SHR reacts to the cholesterol-rich diet by a rise in NAD, i.e. conversely to the reaction observed in the liver of SHR and vascular wall of normotensive rats. Normal refeeding induces a further increase in the content of coenzymes. These results show that the effect of cholesterol-rich diet on the coenzyme content in the SHR is opposite to that in normotensive rats. The renal redox-system NAD+-NAD-H is more sensitive to the cholesterol-rich diet than the liver one, and its coenzyme changes indicate a greater reduction state, a reaction pattern which is typical for renal hypoxia. The results suggest that the cholesterol-rich diet influences the metabolism of the liver, the kidney and the vascular wall in a different way and to a different degree. SHR have a specific type of reaction to this cholesterol-rich diet.

Acetyl Coenzyme A↗
PubMed1982

Adenine nucleotide pool size, adenine nucleotide translocase activity, and respiratory activity in newborn rabbit liver mitochondria.

The adenine nucleotide content (ATP+ADP+AMP) of newborn rabbit liver mitochondria was 6.0 +/- 0.5 nmol/mg mitochondrial protein at birth, increased rapidly to 14.5 +/- 1.7 nmol/mg protein by 2 h postnatal, peaked at 6 h, then decreased gradually to 7.8 +/- 0.6 nmol/mg protein by 4 days postnatal. There was a strong positive correlation (r = 0.82) between the total adenine nucleotide pool size and adenine nucleotide translocase activity in these mitochondria. In contrast, glutamate + malate-supported State 3 respiratory rates remained constant from birth through the first week of life. State 4 rates also remained constant, as did the respiratory control index and uncoupled respiratory rates. The following conclusions are suggested: (1) The maximum rate of translocase activity is limited by the intramitochondrial adenine nucleotide pool size. (2) In newborn rabbit liver mitochondria, the State 3 respiratory rate is not limited by either the adenine pool size or the maximum capacity for translocase-mediated adenine exchange. (3) In contrast to rat, rabbit liver mitochondria are fully functional at birth with regard to respiratory rates and oxidative phosphorylation. (4) The rapid postnatal accumulation fo adenine nucleotides by liver mitochondria, now documented in two species, may be a general characteristic of normal metabolic adjustment in neonatal mammals.

Adenine Nucleotides↗
PubMed1991

Interaction of adenine nucleotides with the adenine nucleotide translocase regulates the developmental changes in proton conductance of the inner mitochondrial membrane.

2-h-old neonatal liver mitochondria, when depleted of adenine nucleotides, showed an 'ohmic' current-voltage relationship and a higher passive proton permeability of the membrane, resembling fetal mitochondrial behaviors for the proton conductance. Incubation of fetal mitochondria with ATP, GDP or carboxyatractyloside promoted a significant reduction in the passive proton permeability of the membrane and the appearance of the characteristic biphasic behavior for the proton conductance. It is concluded that the postnatal increase in intramitochondrial adenine nucleotide concentration promotes, by the interaction of the nucleotides with the adenine nucleotide translocase, the reduction in the passive proton permeability of the mitochondrial membrane, allowing efficient energy conservation in the neonatal liver.

Adenine Nucleotides↗
PubMedDate not supplied

Conformationally restricted adenine nucleotide analogs in mitochondrial adenine nucleotide transport.

The conformationally restricted adenine nucleotide analogs 8,3'anhydro-8-oxy-9-(beta-D-xylofuranosyl)adenine-5'-O-tri(di)-phosphate (I), and 8,2'-anhydro-8-oxy-9-(beta-D-arabinofuranosyl) adenine-5'-O-tri(di)-phosphate (II), were prepared chemically as their alpha-32P-labelled compounds and compared with syn-structured 8-bromo AT(D)P in mitochondrial adenine nucleotide translocation. The experimental findings demonstrate that the heterocycle-ribose orientation affects the carrier mediated adenine nucleotide transport very strongly, i.e. a non fixed adenine heterocycle in the anti region is prerequisite for the bound nucleotide to induce the transfer action of the adenine nucleotide carrier.

Adenine Nucleotides↗
PubMed1981

Photolabelling with 8-azido-adenine nucleotides of adenine nucleotide-binding sites in isolated spinach chloroplast ATPase (CF1).

1. Photolabelling of chloroplast ATPase (CF1) with either 8-azido-ATP or 8-azido-ADP leads to inactivation of the ATPase activity. ATP and ADP protect against the inactivation, whereas AMP dose not. 2. Ca2+ has little if any effect on the degree of inactivation by photolabelling with 8-azido-ADP, but, at the same degree of inactivation, twice as much label is bound in the presence of Ca2+ as in its absence. 3. The degree of inactivation of ATPase and the amount of bound photolabel are independent of the extent of pre-activation of the CF1. 4. Upon extrapolation to complete inactivation, 2 mol label, either 8-azido-ATP or 8-azido-ADP can be bound. 5. In all cases the label is bound specifically to the alpha and beta subunits in almost equal amounts. The location of the bound label is not affected by addition of Ca2+, ATP or ADP.

Adenosine Diphosphate↗
PubMed1970

Equilibrium relations between the cytoplasmic adenine nucleotide system and nicotinamide-adenine nucleotide system in rat liver.

1. The ratio [ATP]/[ADP][P(i)], as measured by direct determination of the three components in rat liver, was found in various nutritional states to have approximately the same value as the ratio [ATP]/[ADP][P(i)] calculated from the concentrations of lactate, pyruvate, glyceraldehyde phosphate and 3-phosphoglycerate on the assumption that lactate dehydrogenase, glyceraldehyde phosphate dehydrogenase and 3-phosphoglycerate kinase are at near-equilibrium in the liver. This implies that the redox state of the NAD couple in the cytoplasm is linked to, and partially controlled by, the phosphorylation state of the adenine nucleotides. 2. The combined equilibrium constant of the glyceraldehyde 3-phosphate dehydrogenase and 3-phosphoglycerate kinase reactions at 38 degrees C and I0.25, was found to be 5.9x10(-6). 3. The fall of the [NAD(+)]/[NADH] ratio in starvation and other situations is taken to be the consequence of a primary fall of the [ATP]/[ADP][HPO(4) (2-)] ratio.

Adenine Nucleotides↗
PubMed1981

[Mathematical modelling of glycolysis and of adenine nucleotide metabolism of human erythrocytes. II. Simulation of adenine nucleotide breakdown following glucose depletion].

The breakdown of adenine nucleotides in human erythrocytes in physiological and alkaline medium at 37 degrees C after glucose depletion is simulated by a mathematical model of energy metabolism. The simulation consists of time dependent solutions of a system of 16 differential equations derived from the stoichiometry of chemical pathways and kinetic properties of enzymes. Starting with the stationary characteristics of the model (M. Schauer et al.: Acta biol. med. germ. 40, 1659, 1981) the results of the simulation were analysed as a function of 1) the share of adenylate deaminase in the degradation of adenine nucleotides and 2) the interaction between adenylate kinase equilibrium and magnesium ions. The experimental data and the simulated concentration changes are in good accord, provided that the assumed activity of adenylate deaminase is very low so that the degradation of adenine nucleotides proceeds mainly via AMP-hydrolysis. The extensive activation of adenylate deaminase during incubation is explained by its sigmoid kinetics with respect to AMP. To improve the results of simulation changes in the adenylate kinase equilibrium have to taken into consideration. These have been measured during incubation of erythrocytes; they can be attributed only partly to the increasing concentration of magnesium ions and to differences among the constants of magnesium association to adenine nucleotides.

Adenine Nucleotides↗
PubMedDate not supplied

[Concentration of free nucleotides and turnover of adenine nucleotides in the liver of birds of different ages].

The content of free nucleotides and exchangeability of adenine nucleotides were studied in the liver of 1- and 18-month cocks. It is established that adenine nucleotides in the young cocks liver account for 40%, uridine nucleotides for 29%, cytidine nucleotides for 13% of the total amount of nucleotides. These ratios are maintained with age but the amount of adenine nucleotides decreases by 35% and that of uridine nucleotides by 22%. Against a background of a relatively constant level of adenine and uridine nucleotides the content of cytidine and guanine nucleotides varies synchronously within wide ranges, which can evidence for the presence of a common mechanism of regulating synthesis of these metabolites. A direct correlation is detected between the amount of adenine nucleotides and their specific radioactivity. This is due to a higher intensity of synthetic processes in young cocks. The inverse correlation is observed in adult cocks, that results from the effect of "label dilution".

Adenine Nucleotides↗
PubMed1991

Guanine-nucleotide- and adenine-nucleotide-dependent regulation of phospholipase D in electropermeabilized HL-60 granulocytes.

We have characterized the regulation of phospholipase D (PLD) in electropermeabilized HL-60 granulocytes in which endogenous phospholipids were pre-labelled with [3H]oleic acid. Treatment of these permeabilized cells with the non-hydrolysable GTP analogues guanosine 5'-[gamma-thio]triphosphate (GTP[S]) and guanosine 5'-[beta gamma-imido]triphosphate induced a sustained (near-linear for up to 60 min) accumulation of phosphatidic acid (PA). In the presence of ethanol a sustained production of phosphatidylethanol (PEt) was also observed. With increasing concentrations of ethanol, PEt formation increased, whereas PA formation declined; this indicated involvement of a PLD-type effector enzyme. The ability of GTP[S] to stimulate this PLD activity was Mg(2+)-dependent and was inhibited by GDP and its non-hydrolysable beta-thio analogue. Ca2+, at concentrations less than or equal to nM, had no effect on the GTP[S]-dependent PLD activity. However, higher concentrations of Ca2+ produced a significant potentiation of this activity. Inclusion of MgATP (greater than or equal to 0.1 mM), but not other nucleoside triphosphates, also induced a large potentiation of GTP[S]-dependent PLD activation. In the absence of guanine nucleotides, MgATP elicited no significant activation of PLD. Significantly, this effect of ATP was not mimicked by adenosine 5'-[beta gamma-methylene]triphosphate, a non-hydrolysable ATP analogue. Rather, this analogue inhibited both basal and ATP-potentiated GTP[S]-dependent PLD activity. This suggests that the ability of ATP to potentiate GTP[S]-dependent PLD activity involves phosphotransferase action rather than simple allosteric effects induced by adenine nucleotide binding. The absolute magnitude of the GTP[S]-dependent PLD activity which could be potentiated by MgATP was decreased by 90% when the permeabilized cells were preincubated for various times before addition of these stimulatory agents. This time-dependent loss of MgATP-induced potentiation was prevented when the permeabilized cells were preincubated in the presence of GTP[S]. These results demonstrate that electropermeabilized HL-60 granulocytes can be used to discriminate synergistic roles for a GTP-binding protein(s) and an ATP-dependent process (kinase?) in the regulation of phospholipase D activity.

Adenine Nucleotides↗
PubMed1986

Neuromodulation by adenine nucleotides, as indicated by experiments with inhibitors of nucleotide inactivation.

The adenine nucleotides AMP, ADP and ATP (3 X 10(-7) M and above) inhibited contractile responses to transmural nerve stimulation in guinea-pig ileum longitudinal muscle via a prejunctional action. Nucleotides assumed to inhibit the degradation of adenine nucleotides were employed to determine whether inhibition of contractile responses was elicited by adenine nucleotides per se, or required breakdown to adenosine. The IMP or 2'-deoxy AMP enhanced the prejunctional inhibitory effect elicited by AMP. A similar enhancement of the inhibitory effect of ADP and ATP was seen after administration of IDP and ITP, respectively. The inhibitory effect of adenosine was not enhanced by inosine, IMP or IDP. The 5'-nucleotidase inhibitor, TDP enhanced inhibition elicited by ADP. In contrast, alpha, beta-meADP did not influence the prejunctional inhibitory effect elicited by the adenine nucleotides. However, the combination of alpha, beta-meADP and IMP enhanced the inhibitory effect of ATP. The postjunctional contractile effect elicited by ADP and ATP was enhanced by pretreatment with inosine nucleotides, alpha, beta-meADP or TDP, indicating decreased inactivation of ADP and ATP during concurrent nucleotide administration. The fact that the prejunctional effect of adenine nucleotides can be enhanced by forms of pretreatment known to antagonize the breakdown of adenine nucleotides, constitutes strong evidence for prejunctional action per se by adenine nucleotides.

Adenine Nucleotides↗
PubMed1979

Relationship between protein synthesis and secretion in liver cells and the state of the adenine nucleotide system.

Adenine nucleotide levels could be precisely and reproducibly adjusted in liver cell suspensions by partially depleting the ATP pool with D-fructose or glycerol. Thus, it was possible to quantitatively correlate rates of protein synthesis and secretion with intracellular levels of ATP and with derived parameters, such as the adenylate energy charge. Half the maximum rate of incorporation of leucine into protein was observed at an energy charge of 0.80, a ratio of ATP to ADP of 2.6, and an ATP level of 1.05 mumol per g of wet cells. Proteins were secreted with half the maximum rate at an energy charge of 0.85, a ratio of ATP to ADP of 3.1 and an ATP concentration of 1.1 mumol per g of wet cells. Protein secretion did not depend on continued synthesis. Inhibitors of oxidative phosphorylation inhibited protein secretion in addition to protein synthesis, in contrast to observations by other authors on liver slices.

Adenine Nucleotides↗