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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activities of adenylate kinase, AMP-deaminase and 5'-nucleotidase in various tissues of the rat were studied. The activity of the forward adenylate kinase reaction (ATP + AMP----2 ADP) against the back one (2 ADP----ATP + AMP) was predominant. The liver was shown to contain two, while the blood serum--three adenylate kinase isoenzymes. In the skeletal muscles, the catabolism of adenylic acid involving AMP-deaminase and 5'-nucleotidase predominantly occurred via deamination, in the liver--via dephosphorylation, while in the leucocytes, erythrocytes and blood serum the activity of these processes was essentially the same. In vitro, ATP enhanced the activity of AMP-deaminase in the liver, leucocytes and erythrocytes and decreased it in the blood serum. Under effects of ATP, the activity of 5'-nucleotidase in the leucocytes and blood serum was markedly elevated, that in the liver and erythrocytes was unaffected.
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PMID:[Role of adenylate kinase, AMP deaminase and 5'-nucleotidase in the metabolism of adenylic nucleotides]. 609 96

The structural changes accompanying digitonin-induced release of enzymes and metabolites from isolated hepatocytes have been studied by scanning and transmission electron microscopy. In the initial phase, characterized by total release of the cytosolic marker enzyme, lactate dehydrogenase, the plasma membrane was immediately damaged, rapidly followed by extensive damage to the endoplasmic reticulum. The shape of the cell, however, was maintained, and the mitochondria and nucleus remained tightly held together by the cytoskeleton. Mitochondria remained intact initially, whereas the cytosol became less electron dense and the nuclear chromatin was more dispersed. An intermediate phase was characterized by total release of adenylate kinase and most of the glucose-6-phosphatase, marker enzymes for the mitochondrial intermembrane space and the endoplasmic reticulum, respectively. The outer mitochondrial membrane was ruptured, but mitochondria maintained their normal matrix electron density. In the final phase, characterized by the beginning of citrate synthase release from the mitochondrial matrix space, the mitochondria became swollen, and only the nucleus, inner and outer mitochondrial membranes, and the cytoskeleton could be clearly distinguished. Although the plasma membrane could not be readily discerned in electron micrographs after the initial phase, the plasma membrane marker enzyme 5'-nucleotidase remained associated with digitonin-treated hepatocytes. Acetyl-CoA carboxylase was released much more slowly than lactate dehydrogenase, indicating some severe restriction on its release. The release of acetyl-CoA carboxylase closely paralleled the release of glucose-6-phosphatase. The controlled exposure of hepatocytes to digitonin, therefore, leads to the sequential release of soluble, compartmentalized cellular components and some membrane-bound components, but the mitochondrial membrane, cytoskeleton and the nucleoskeleton survive even long-term digitonin treatment.
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PMID:Structural changes of isolated hepatocytes during treatment with digitonin. 614 31

Adenosine 5'-triphosphate (ATP) was catabolized by whole cells and cell-free extracts of Rickettsia typhi to adenosine 5'-diphosphate (ADP) and then to adenosine 5'-monophosphate (AMP), the end product of ATP catabolism under the experimental conditions used. The only intermediate of the pathway from ATP to AMP which was identified by thin-layer chromatography and quantitated by the (14)C content was ADP, whereas products such as adenine, adenosine, hypoxanthine, inosine, and inosine 5'-monophosphate were not detected. The enzymes which could be theoretically responsible for the catabolism or the anabolism of AMP were not detected by standard assay procedures. Most importantly, 5'-nucleotidase or nonspecific phosphatase and AMP nucleosidase activities were undetectable under a variety of experimental conditions. Although these two enzymes remove AMP from the adenylate pool in other cells, they are apparently nonfunctional in R. typhi. The biosynthesis of ATP was initiated by adenylate kinase because no adenine phosphoribosyltransferase or adenosine kinase could be detected. Furthermore, AMP was transported intact without prior dephosphorylation. These observations suggest that for R. typhi the in vivo activity of adenine nucleotide interconversion was limited to the nucleotides, with AMP being the end product of ATP catabolism, and that the salvage of purine bases and nucleosides was not an essential feature of purine metabolism. These results elucidate the findings of a previous study which showed that in the absence of glutamate as a source of energy, the adenylate energy charge of resting cells of R. typhi is drastically lowered by the high proportion of AMP.
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PMID:Adenine nucleotide degradation by the obligate intracellular bacterium Rickettsia typhi. 624 88

A series of AMP analogs in which a terminal carboxylate residue, linked to C 4' of the ribose moiety of adenosine by zero, one, or two methylene groups (1,2,3) or by the unsaturated ethylidene link (4) replaces the phosphate anion, is tested for activity as substrates or effectors of three enzymes known to interact with AMP with a different degree of specificity. 2-4 are substrates of AMP aminohydrolase, 3 and 4 are competitive inhibitors of adenylate kinase, and all acids produce competitive inhibition of the least specific enzyme, 5'-nucleotidase. These activities can be correlated with the intramolecular flexibility of anionic substituent and adenine base which in turn is expressed in typical shifts of the proton magnetic resonance signal of purine H-8. The uronic acid 1, having a rigid molecular conformation, is inactive towards two AMP-dependent enzymes and little active with the third, indicating that this type of compound is not suitable as a nucleotide antagonist whereas nucleoside carboxylates of type 2 and 3 have a higher potential as effectors of nucleotide metabolism.
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PMID:A study of the substrate and inhibitor specificities of AMP aminohydrolase, 5'-nucleotidase, and adenylate kinase with adenosine carboxylates of variable chain length. 624 59

The present investigations on rat lung show that metabolic changes occurring around the 20th gestational day are accompanied by multiple alterations in the quantitative pattern of enzymes. This involves increases in two lysosomal enzymes (N-acetyl beta-glucosaminidase and beta-galactosidase) and a rise and fall in pyruvate kinase and alpha-glucosidase. The striking transient upsurge of adenylate kinase, however, is postponed until after birth. The normal diminution of thymidine kinase and peptidylproline hydroxylase is drastically enhanced by an injection of cortisol to fetal rats. Studies on human pulmonary tissues consisted in determining enzyme concentration from the ninth to the 21st week of gestation and an histologically normal adult lungs. The results show that the 15th to the 21st week of gestation is the period of increase in pyruvate kinase, adenylate kinase and alpha-glucosidase. The rise during the development of several enzymes (e.g., 5'-nucleotidase, alkaline phosphatase, and gamma-glutamyl transpeptidase) and the decline in thymidine kinase and peptidylproline hydroxylase, however, dose not begin until after the 21st week of gestation.
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PMID:Phosphotransferases and lysosomal enzymes in fetal human and rat lung. 626 41

The adenosine kinase activity present in a soluble preparation from rat liver was investigated using formycin A (FoA), a fluorescent analog of adenosine as the phosphoryl acceptor and ATP as the donor. Reversed-phase high-performance liquid chromatography (h.p.l.c.) was used to separate substrate from product, and the progress of the phosphorylation reaction was followed by monitoring fluorometrically the amount of formycin 5'-monophosphate (FoMP), and the AMP analog, that was formed. The results showed that while FoMP was formed during the reaction indicating that an adenosine kinase activity was present, both formycin 5'-di- and triphosphate (FoDP and FoTP respectively), the corresponding analogs of ADP and ATP, were also formed, suggesting than an adenylate kinase activity was present. This result was confirmed with FoMP as the substrate and showing the formation of FoDP and FoTP. Other experiments carried out with FoMP as the substrate revealed the formation of FoA. Taken together, these results indicated that a 5'-nucleotidase activity as well as an adenylate kinase was present. Using this analog and h.p.l.c., it has been possible to demonstrate for the first time in an in vitro system the complete salvage of a nucleoside to the triphosphate level.
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PMID:In vitro processing of the adenosine analog formycin A to the mono-, di-, and triphosphate by a soluble multienzyme system from mouse liver. 628 Jul 86

The adenosine deaminase, 5'-nucleotidase, AMP-aminohydrolase and adenylate kinase activities and thymostimulin influence on these indices in vivo were studied in rat thymus and spleen lymphocytes in the latent period of DMBA-induced mammary carcinogenesis. The adenosine deaminase activity was established to increase while 5'-nucleotidase and AMF-aminohydrolase activity to decrease in the thymocytes of intact animals treated with thymostimulin; the adenylae kinase activity of spleen lymphocytes decreased as compared with that in the rats not treated with the preparation. The dynamics of changes in the investigated enzymes in activities in lymphocytes was of wave-like pattern in the latent period. The treatment of animals with thymostimulin in this period normalized adenosine deaminase activity and decreased the activity of the other enzymes in these cells.
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PMID:[Influence of thymostimulin on the activity of certain enzymes of adenosine and AMP metabolism in lymphocytes of rats with mammary cancer]. 628 53

We have studied purine metabolism in mononuclear and polymorphonuclear cells from uraemic patients using microradiochemical enzyme assays and high-pressure liquid chromatography. In mononuclear cell lysates the mean activities of adenosine deaminase (EC 3.5.4.4) and 5'-nucleotidase (EC 3.1.3.5) were significantly diminished. The activities of adenylate kinase (EC 2.7.4.3), purine nucleoside phosphorylase (EC 2.4.2.1), adenine phosphoribosyltransferase (EC 2.4.2.7), and hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) were not significantly different in the two groups. The activities of adenosine deaminase and adenine phosphoribosyltransferase were reduced in the polymorphonuclear cell lysates. No clear differences emerged in the concentration of adenine nucleotides in the mononuclear cells. The significance of these changes, which are less marked than those in erythrocytes, is discussed with reference to the immunodeficiency associated with uraemia.
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PMID:Activities of enzymes involved in purine metabolism and some related adenine nucleotide concentrations of leucocytes in renal failure. 629 37

The components of the ectonucleotidase pathway at the immunoaffinity-purified striatal cholinergic synapse have been studied. The ecto-ATPase (EC 3.6.1.15) had a Km of 131 microM, whereas the ecto-ADPase (EC 3.6.1.6) had a Km of 58 microM, was Ca(2+)-dependent, and was inhibited by the ATP analogue 5'-adenylylimidodiphosphate (AMPPNP). The ecto-5'-nucleotidase (EC 3.1.3.5) had a Km of 21 microM, was inhibited by AMPPNP and alpha,beta-methylene ADP, and by a specific antiserum. The Vmax values of the ATPase, ADPase, and 5'-nucleotidase enzymes present at this synapse were in a ratio of 30:14:1. Very little ecto-adenylate kinase activity was detected on these purified synapses. The intraterminal 5'-nucleotidase enzyme, which amounted to 40% of the total 5'-nucleotidase activity, was inhibited by AMPPNP, alpha,beta-methylene ADP, and the antiserum, and also had the same kinetic properties as the ectoenzyme. The time course of ATP degradation to adenosine outside the nerve terminals showed a delay, followed by a period of sustained adenosine production. The delay in adenosine production was proportional to the initial ATP concentration, was a consequence of feedforward inhibition of the ADPase and 5'-nucleotidase, and was inversely proportional to the ecto-5'-nucleotidase activity. The function and characteristics of this pathway and the central role of 5'-nucleotidase in the regulation of extraterminal adenosine concentrations are discussed.
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PMID:Production of adenosine from extracellular ATP at the striatal cholinergic synapse. 841 43

Extracellular nucleotides interact with specific receptors on the cell surface and are locally metabolized by ecto-nucleotidases. Biochemical characterization of the ATPase and ADPase activities detected in rat heart sarcolemma, under conditions where mitochondrial ATPase and adenylate kinase were blocked, supports our proposal that both activities correspond to a single enzyme, known as ATP-diphosphohydrolase or apyrase. The physiological function of this enzyme could be dephosphorylation of the nucleotides present in the interstitial heart compartment acting together with 5'-nucleotidase. Both hydrolytic activities have similarities in: sarcolemma localization, bivalent metal ion dependence, optimum pH, effect of several amino acid residue modifiers, competitive inhibition of nucleotide analogs, and broad nucleoside di-and triphosphate specificity. The ATPase activity could not be separated from the ADPase either through isoelectrofocusing or electrophoresis under acid conditions.
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PMID:ATP-diphosphophydrolase activity in rat heart tissue. 886 7


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