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At least 19 recordsLinked to original sources
PubMed2001

Adenosine diphosphate sugar pyrophosphatase prevents glycogen biosynthesis in Escherichia coli.

An adenosine diphosphate sugar pyrophosphatase (ASPPase, EC ) has been characterized by using Escherichia coli. This enzyme, whose activities in the cell are inversely correlated with the intracellular glycogen content and the glucose concentration in the culture medium, hydrolyzes ADP-glucose, the precursor molecule of glycogen biosynthesis. ASPPase was purified to apparent homogeneity (over 3,000-fold), and sequence analyses revealed that it is a member of the ubiquitously distributed group of nucleotide pyrophosphatases designated as "nudix" hydrolases. Insertional mutagenesis experiments leading to the inactivation of the ASPPase encoding gene, aspP, produced cells with marginally low enzymatic activities and higher glycogen content than wild-type bacteria. aspP was cloned into an expression vector and introduced into E. coli. Transformed cells were shown to contain a dramatically reduced amount of glycogen, as compared with the untransformed bacteria. No pleiotropic changes in the bacterial growth occurred in both the aspP-overexpressing and aspP-deficient strains. The overall results pinpoint the reaction catalyzed by ASPPase as a potential step of regulating glycogen biosynthesis in E. coli.

Adenosine Diphosphate↗
PubMed1977

Conversion of ADP-ribose to 5'-AMP by alkaline treatment and its use for an optical quantitation of mono and poly(ADP-ribose) residues in the micromolar range.

ADP-Ribose is nearly quantitatively split to 5'-AMP by treatment with alkali at elevated temperatures. This unique behaviour, which is not shown by ADP and other adenine derivatives, was used as the basis of an optical test for the selective determination of ADPR in the presence of other adenine compounds including RNA. Poly(ADPR) could also be quantified when the polymer was degraded by poly(ADPR) glycohydrolase prior to alkaline treatment. When combined with the determination of the terminal AMP residues released by phosphodiesterase I treatment, the chain length of the polymer could be calculated. Application of the method to the quantitation of protein-bound mono(ADPR) residues in Ehrlich ascites tumor cells under different growth conditions is described.

Adenosine Diphosphate Sugars↗
PubMed2004

Most of ADP x glucose linked to starch biosynthesis occurs outside the chloroplast in source leaves.

Sucrose and starch are end products of two segregated gluconeogenic pathways, and their production takes place in the cytosol and chloroplast of green leaves, respectively. According to this view, the plastidial ADP.glucose (ADPG) pyrophosphorylase (AGP) is the sole enzyme catalyzing the synthesis of the starch precursor molecule ADPG. However, a growing body of evidences indicates that starch formation involves the import of cytosolic ADPG to the chloroplast. This evidence is consistent with the idea that synthesis of the ADPG linked to starch biosynthesis takes place in the cytosol by means of sucrose synthase, whereas AGP channels the glucose units derived from the starch breakdown. To test this hypothesis, we first investigated the subcellular localization of ADPG. Toward this end, we constructed transgenic potato plants that expressed the ADPG-cleaving adenosine diphosphate sugar pyrophosphatase (ASPP) from Escherichia coli either in the chloroplast or in the cytosol. Source leaves from plants expressing ASPP in the chloroplast exhibited reduced starch and normal ADPG content as compared with control plants. Most importantly however, leaves from plants expressing ASPP in the cytosol showed a large reduction of the levels of both ADPG and starch, whereas hexose phosphates increased as compared with control plants. No pleiotropic changes in photosynthetic parameters and maximum catalytic activities of enzymes closely linked to starch and sucrose metabolism could be detected in the leaves expressing ASPP in the cytosol. The overall results show that, essentially similar to cereal endosperms, most of the ADPG linked to starch biosynthesis in source leaves occurs in the cytosol.

Adenosine Diphosphate Glucose↗
PubMed1979

Cholera toxin-catalysed ADP-ribosylation of erythrocyte proteins: general properties.

Upon incubation of lysed pigeon erythrocytes with NAD, adenosine diphosphate-ribose (ADP-ribose) is incorporated into nuclear poly ADP-ribose and into an unidentified acid-insoluble product of the cytosol. The properties of these incorporations have been examined and a method developed for reducing their amount whilst retaining the sensitivity of the lysate to cholera toxin. This method has allowed the detection and description of a set of cholera toxin-specific ADP-ribose transfers to membrane-bound and soluble proteins under conditions that lead to adenylate cyclase activation.

Adenosine Diphosphate Sugars↗
PubMed1976

An investigation of the nicotinamide-adenine dinucleotide-induced 'tightening' of the structure of glyceraldehyde 3-phosphate dehydrogenase.

An investigation was made of the effect of NAD+ analogues on subunit interactions in yeast and rabbit muscle glyceraldehyde 3-phosphate dehydrogenases by using the subunit exchange (hybridization) method described previously [e.g. see Osborne & Hollaway (1975) Biochem. J. 151, 37-45]. The ligands ATP, ITP, ADP, AMP, cyclic AMP and ADP-ribose like NADH, all caused an apparent weakening of intramolecular subunit interactions, whereas NAD+ caused an apparent increase in the stability of the tetrameric enzyme molecules. A mixture of NMN and AMP, although it did not simulate completely the NAD+-induced 'tightening' of the enzyme structure, did result in a more than 20-fold decrease in the rate of subunit exchange compared with that in the presence of AMP alone. These results show that occupancy of the NMN subsite of the enzyme NAD+-binding site is insufficient in itself to give the marked tightening of the enzyme structure induced by NAD+. The 'tightening' effect is specific in that it seems to require a phosphodiester link between NMN and ADP-ribose. These effects are discussed in terms of the detailed X-ray structure of the lobster holoenzyme [Buehner et al. (1974) J. Mol. Biol. 90, 25-49].

Adenosine Diphosphate↗
PubMed1978

Determination of ADP-ribose and poly(ADP-ribose) by a new radioimmunoassay.

A specific and sensitive radioimmunoassay for ADP-ribose has been developed on the basis of the selective conversion of ADP-ribose to 5'-AMP by alkaline treatment. Antibodies highly specific against 5'-AMP allowed quantification of ADP-ribose converted to 5'-AMP in the range of 1-40 pmol, and in the presence of large quantities of nucleic acids or 3'-AMP. Poly(ADP-ribose) could also be determined when degraded to ADP-ribose by poly(ADP-ribose) glycohydrolase. Determination of the chain length of purified polymer was possible by a parallel determination of ADP-ribose residues after glycohydrolase treatment and of 5'-AMP from the non-reducing end obtained by phosphodiesterase catalyzed hydrolysis. The high specificities of the alkaline conversion of ADP-ribose to 5'-AMP and of the radioimmunoassay for 5'-AMP allowed quantification of protein-bound ADP-ribose residues in crude tissue extracts as verified by comparison with chromatographically purified samples.

Adenosine Diphosphate Sugars↗
PubMedDate not supplied

[On different forms of glyceraldehyde-3-phosphate dehydrogenase].

Evidence is presented for the structural differences between rat and rabbit skeletal muscle glyceraldehyde-3-phosphate dehydrogenases. Glyceral-dehyde-3-phosphate dehydrogenases isolated from frozen and fresh rat skeletal muscle were found to have different temperature stability and chromatographic behavior on CM-cellulose. Different nucleotide content of the preparations (NAD on one hand, and products of its degradation - ADP-ribose, AMP and adenosine, on the other) is shown to account for the observed effects.

Adenosine↗
PubMedDate not supplied

[Possible nature of negative cooperation in D-glyceraldehyde-3-phosphate dehydrogenase].

Some considerations concerning the detailed mechanism of negative cooperativity in GPD are proposed. The hypothesis represents a modification of the sequential model (Koshland et al.) taking into account last experimental data about the binding of NAD analogs and fragments. Two main facts have been used as a basis for the model: 1. Neither ADP-ribose nor nicotinamide mononucleotide (NMN) fragments of NAD show negative cooperative binding to GPD. 2. Neither modifications of adenine and nicotinamide part of NAD (epsilon-NAD, hypoxantine-NAD, oxidized and reduced-NAD) nor enzyme modifications by various reagents acting in the catalytic site affect considerably the cooperativity of coenzyme binding although the affinity between enzyme and coenzyme (analogs) substantially changes depending on the nature of modification. Probably the structural integrity of a coenzyme molecule is necessary for the cooperative binding to GPD. On the other hand, numerous modification studies can be interpreted as proving the absence of direct participation of adenine and nicotinamide rings in the mechanism of negative interactions between NAD-binding sites. It appears reasonable to assume that direct or indirect interactions of riboseAD and pyrophosphate groups of NAD with the "loop" of adjacent subunit might be necessary for the tight coenzyme binding to the first active site of the r-dimer(s) symmetric across the R-axis. After the tight binding of the first NAD molecule on r-dimer with the "loop" participation, the symmetrical movement of second "loop" might be highly restricted. It was postulated that only asymmetric conformational transition is possible in contact areas between subunits across the R-axis. Such asymmetric rearrangement can explain the nonequivalent binding of NAD to a prior symmetric dimmer(s).

Adenosine Diphosphate Sugars↗
PubMed1977

A 13C NMR study of poly(adenosine diphosphate ribose) and its monomers: evidence of alpha-(1'' leads to 2') ribofuranosy1 ribofuranoside risidue.

The 13C NMR spectra of poly(adenosine diphosphate ribose), ribosyl adenosine 5', 5''-bis(phosphate) and related compounds were analyzed. The structure of the ribose-ribose linkage was determined as alpha-(1'' leads to 2')ribofuranosyl ribofuranoside, from the 13C chemical shifts of methyl-alpha- and methyl-beta-D-ribofuranosides, and from the downfield displacements of 13C NMR signals by glycosidic bond formation.

Adenosine Diphosphate Sugars↗
PubMed1975

Macromolecular enzymatic product of NAD+ in liver mitochondria.

Rat liver mitochondria contain a Mg2+-requiring system that transfers the ADP-ribose moiety of NAD+ to an acceptor protein. The enzyme system was extracted in a soluble form and the ADP-ribosylated protein product was isolated by hydroxyapatite and Sephadex chromatography. The ADP-ribosylated protein product has a molecular weight of 100,000 and can be dissociated into subunits of 50,000 daltons by sodium dodecyl sulfate gel electrophoresis. Incubation of the isotopically labeled ADP-ribosylated protein with nicotinamide and a mitochondrial extract yields labeled NAD+, indicating apparent reversibility of the reaction. Enzymatic degradation of the ADP-ribosylated protein with snake venom phosphodiesterase liberates AMP and ADP-ribose or its isomer. Identification of these products and reversibility of the reaction show that the ADP-ribose moiety of NAD+ is the molecular species that is transferred to the acceptor protein. A fraction of the protein-bound ADP-ribose appears to be present as an an oligomer. The enzymatic protein-ADP-ribosylating reaction is inhibited by nicotinamide, ADP-ribose, the fluorophosphate of AMP, and picrylsulfonic acid.

Adenosine Diphosphate Sugars↗
PubMed1987

Direction of elongation of poly(ADP-ribose) chains. Addition of residues at the polymerase-proximal terminus.

The mechanism of elongation of poly(ADP-ribose) on poly(ADP-ribose) polymerase was examined in two ways. The first technique involved a pulse-chase protocol. Poly(ADP-ribose) polymerase was labeled with radioactive NAD, excess precursor was removed by rapid gel filtration chromatography, and nonradioactive NAD was supplied for a second incubation. The products were released with alkali and digested with venom phosphodiesterase which generates AMP uniquely from the distal terminus. The distal residue that was labeled during the pulse remained at the distal terminus and was not converted to an internal residue during the chase. The second technique employed the NAD analog, 2'-deoxyNAD (dNAD), which can engage in mono-ADP-ribose addition reactions but lacks the 2'-OH that is required for polymer formation. dNAD inhibits ADP-ribose incorporation competitively but is not incorporated at the enzyme-distal chain terminus. These findings are inconsistent with a model of poly(ADP-ribose) synthesis in which new residues are added to the 2'-OH terminus of the growing chain, distal to the polymerase attachment. They are consistent with the alternative possibility that new residues are added at the 1" terminus, adjacent to the polymerase. Any such "proximal addition" model requires that there be at least two active center sites (akin to the ribosomal A and P sites), which at a certain stage of each elongation cycle will be occupied by ADP-ribose monomers and ADP-ribose polymers, respectively. Although dNAD does not enter poly(ADP-ribose), it does engage in a slow side reaction whereby a single dADP-ribose residue is added covalently to the polymerase itself, thereby inactivating the enzyme.

ADP Ribose Transferases↗
PubMed1985

Poly(ADP-ribosylation) at successive stages of rooster spermatogenesis. Levels of polymeric ADP-ribose in vivo and poly(ADP-ribose) polymerase activity and turnover of ADP-ribosyl residues in vitro.

Rooster testis cells were separated by sedimentation at unit gravity and the in vivo levels of polymeric ADP-ribose were determined both in intact cells and isolated nuclei by fluorescence methods. Poly(ADP-ribose) polymerase activity was assayed after cell permeabilization or after isolation of nuclei. The turnover of ADP-ribosyl residues was determined in isolated nuclei using benzamide. The content of poly(ADP-ribose), the poly(ADP-ribose) polymerase activity, and the turnover of ADP-ribosyl residues, decreased during the differentiation of the germinal cell line, especially at the end of spermiogenesis. Treatment of cells with 1 mM dimethyl sulfate for 1 h resulted in a marked stimulation of poly(ADP-ribose) polymerase activity in meiotic and premeiotic cells and also in round and late spermatids. The enzymatic activity was not detected and could not be induced in mature spermatozoa. These cells, however, still contained polymeric ADP-ribose with a 2% of branched form.

Adenosine Diphosphate Ribose↗