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PubMed1977

Histochemical evaluation of thiamine pyrophosphatase activity during first molar odontogenesis of the neonatal hairless mouse.

Localization of thiamine pyrophosphatase activity has been evaluated in the developing first molar of the neonatal hairless mouse. Postnatal animals from parturition to five days of age were decapitated and the severed heads frozen and sectioned in a frontal plane on a cryostat. 14 micron thick sections were fixed and subsequently incubated for thiamine pyrophosphatase activity according to the method of GOLDFISCHER et al. (1971). The tissue was visualized, dehydrated, cleared and mounted. Light microscopy was utilized in evaluating thiamine pyrophosphatase activity. Thiamine pyrophosphatase activity in the first molar of the hairless mouse is presented in tabular form and compared to similar data for the Swiss albino mouse. Enzyme activity increased as the metabolic activities of various cell layers increased. Thus, thiamine pyrophosphatase activity appeared to be related to the degree of differentiation and functional completency of the odontogenic tissues in the hairless mouse.

Animals↗

PubMed1989

Purification and properties of vacuolar membrane proton-translocating inorganic pyrophosphatase from mung bean.

Inorganic pyrophosphatase was purified from the vacuolar membrane of mung bean hypocotyl tissue by solubilization with lysophosphatidylcholine and QAE-Toyopearl chromatography. The molecular mass on sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 73,000 daltons. Among the amino-terminal first 30 amino acids are 25 nonpolar hydrophobic residues. For maximum activity, the purified pyrophosphatase required 1 mM Mg2+ and 50 mM K+. The enzyme reaction was stimulated by exogenous phospholipid in the presence of detergent. Excess pyrophosphate as well as excess magnesium inhibited the pyrophosphatase. The enzyme reaction was strongly inhibited by ATP, GTP, and CTP at 2 mM, and the inhibition was reversed by increasing the Mg2+ concentration. An antibody preparation raised in a rabbit against the purified enzyme inhibited both the reactions of pyrophosphate hydrolysis of the purified preparation and the pyrophosphate-dependent H+ translocation in the tonoplast vesicles. N,N'-Dicyclohexylcarbodiimide became bound to the purified pyrophosphatase and inhibited the reaction of pyrophosphate hydrolysis. It is concluded that the 73-kDa protein in vacuolar membrane functions as an H+-translocating inorganic pyrophosphatase.

Amino Acid Sequence↗

PubMedDate not supplied

[Various physico-chemical properties of inorganic pyrophosphatase from the mouse spleen].

Manganese, calcium and mercury ions, as well as p-chloromercury benzoate and dithiothreitol are studied for their effect on the activity of inorganic pyrophosphatase (EC 3.6.1.1) of mice spleen. It is shown that Ca2+ and Mn2+ are inhibitors of this enzyme, but Mn2+ in low concentrations may replace Mg2+ in the pyrophosphatase reaction. Hg2+ and p-chloromercury benzoate inhibit the pyrophosphatase activity essentially but not completely. Mice spleen pyrophosphatase is very labile: its preincubation without the substrate for 30 min at 37 degrees C leads to a complete loss of the activity. Neither glycerol, nor glutathione and cysteine but magnesium ions, dithiothreitol and 2-mercaptoethanol protect the enzyme from inactivation. The enzyme is purified by the sulphate ammonium salting-out, gel filtration on Sephadex G-100 as well as by isoelectrofocusing in 5% PAAG. Then pyrophosphatase is eluted from gel and subjected to electrophoresis in the plane layer of the linear gradient of 5-15% PAAG with SDS or 5-25% PAAG without denaturing conditions. One zone corresponding to the molecular mass of 70 kDalton is obtained. It is splitted into two zones in electrophoresis with SDS and 2-mercaptoethanol.

Animals↗

PubMed1975

Studies on matrix vesicles isolated from chick epiphyseal cartilage. Association of pyrophosphatase and ATPase activities with alkaline phosphatase.

Fractions composed primarily of cells (Fraction I), membrane fragments (Fraction II) and matrix vesicles (Fraction III) were isolated from chick epiphyseal cartilage. The characteristics of the alkaline phosphatase (EC 3.1.3.1), pyrophosphatase (EC 3.6.1.1) and ATPase (EC 3.6.1.3) activities in the matrix vesicle fraction were studied in detail. Mg-2-+ was not absolutely essential to any of the activities, but at low levels was stimulatory in all cases. Higher concentrations inhibited both pyrophosphatase and ATPase activities. Both the stimulatory and inhibitory effects were pH-dependent. Ca-2-+ stimulated all activities weakly in the absence of Mg-2-+. However, when Mg-2-+ was present, Ca-2-+ was slightly inhibitory. Thus, none of the activities appear to have a requirement for Ca-2-+, and hence would not seem to be involved with active Ca-2-+ transport in the typical manner. The distribution of alkaline phosphatase, pyrophosphatase, and Mg-2-+ ATPase activities among the various cartilage fractions was identical, and concentrated primarily in the matrix vesicles. Conversely, the highest level of (Na-+ + K-+)-ATPase activity was found in the cell fraction. All activites showed nearly identical sensitivities to levamisole (4 - 10-3 M) which caused nearly complete inhibition of alkaline phosphatase and pyrophosphatase. About 10-15% of the ATPase activity was levamisole-insensitive. The data are consistent with the concept that the Mg-2-+-ATPase and pyrophosphatase activities of matrix vesicles stem from one enzyme, namely, alkaline phosphatase.

Adenosine Triphosphatases↗

PubMed1984

Isolation and subunit composition of membrane inorganic pyrophosphatase from rat-liver mitochondria.

The activity of inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) extracted from rat-liver mitochondria with sodium cholate is distributed between three enzyme forms (I-III) which originally reside in the matrix (I) or the inner membrane (II and III). The three forms of pyrophosphatase were separated by means of hydroxyapatite chromatography. The Mr values for enzymes I-III, were 60 000, 120 000 and 210 000, respectively. Membrane pyrophosphatase II, which predominates, was purified to homogeneity. Its molecule consists of two subunits with Mr of 28 000 and 35 000 giving different peptide maps upon BrCN cleavage and polyacrylamide gel electrophoresis. The results suggest that pyrophosphatase II may represent a catalytic part of the membrane pyrophosphatase of these mitochondria.

Animals↗

PubMed2006

The specific, submicromolar-Km ADP-ribose pyrophosphatase purified from human placenta is enzymically indistinguishable from recombinant NUDT9 protein, including a selectivity for Mn2+ as activating cation and increase in Km for ADP-ribose, both elicited by H2O2.

Free ADP-ribose is a putative second messenger and also a potentially toxic compound due to its non-enzymic reactivity towards protein side chains. ADP-ribose hydrolysis is catalysed by NDP-sugar/alcohol pyrophosphatases of differing specificity, including a highly specific, low-K(m) ADP-ribose pyrophosphatase. In humans, a submicromolar-K(m) ADP-ribose pyrophosphatase has been purified from placenta, while recombinant NUDT9 has been described as a similarly specific enzyme with a nudix motif, but with a 10(2)-10(3) higher K(m). Here, a comparative study of both proteins is presented showing that they are in fact enzymically indistinguishable; crucially, they both have submicromolar K(m) for ADP-ribose. This study firmly supports the view that the ADP-ribose pyrophosphatase present in human tissues is a product of the NUDT9 gene. In addition, this study reveals previously unknown properties of both enzyme forms. They display the same, differential properties in the presence of Mg(2+) or Mn(2+) as activating cations with respect to substrate specificity, ADP-ribose saturation kinetics, and inhibition by fluoride. Treatment with H(2)O(2) alters the Mg(2+)/Mn(2+) responses and increases the K(m) values for ADP-ribose, changes that are reversed by DTT. The results are discussed in relation to the proposed roles for ADP-ribose in oxidative/nitrosative stress and for ADP-ribose pyrophosphatase as a protective enzyme whose function is to limit the intracellular accumulation of ADP-ribose.

Adenosine Diphosphate Ribose↗

PubMed1997

A calcium-metalloribozyme with autodecapping and pyrophosphatase activities.

A previously-isolated ribozyme with capping activity has self-decapping activity, here characterized alongside its additional, somewhat parallel, pyrophosphatase reaction. Decapping is 10-50 times slower than the pyrophosphatase activity, depending on pH. The RNA accelerates pyrophosphate release 170 000 times over a control composed of randomized pppRNA, and 5' capped RNA accelerates decapping 1000-fold over random capped RNA. Triphosphate-linked G(5')pppRNA also supports an unusual cap-exchange reaction, exchanging its cap with guanosine 5'-tetraphosphate to form pentaphosphate-linked G(5')pppppRNA. GDP, a capping reactant for the RNA, appears to suppress both decapping and pyrophosphatase activities. Autodecapping and pyrophosphatase activities have in common an unusual divalent metal ion requirement for Ca2+ or less effectively Mn2+, and both are active over a broad pH range of 4.5-9. 0. These characteristics resemble the capping activity of the same RNA. Kinetic analysis reveals a well-defined Ca2+-RNA complex, and Mg2+ and Sr2+ act as competitive inhibitors of Ca2+. A strong Ca2+-binding site is suggested by a low KM of 40-60 microM at pH >/= 7.0. The role of Ca2+ in these reactions can be surmized from literature data on reactivity of nucleotide phosphates. Pyrophosphatase, capping, and decapping activities of isolate 6 RNA are apparently carried out by a single reaction center, whose rate of reaction with all nucleophiles sums to a constant total rate. This suggests a universal rate-limiting step. Versatile activation of alpha-phosphate by this reaction center raises the possibility of combinatorial ribozymes.

Base Sequence↗

PubMed1967

Association of inorganic-pyrophosphatase activity with human alkaline-phosphatase preparations.

1. The inorganic-pyrophosphatase activity of alkaline phosphatases prepared from human liver and small intestine was investigated at different stages of purification. 2. Both liver and intestinal preparations possessed pyrophosphatase activity at all stages of purification, and the two types of activity were not separated by gel filtration or by anion-exchange or cation-exchange chromatography. 3. After starch-gel electrophoresis of the tissue extracts, the zones of pyrophosphatase activity coincided exactly with alkaline-phosphatase zones. 4. Hydrolysis of each type of substrate was inhibited by the presence of the other, and a constant ratio of alkaline-phosphatase activity to pyrophosphatase activity was maintained during inactivation of the enzymes by incubation at 55 degrees . 5. These results are consistent with the view that alkaline phosphatases are also inorganic pyrophosphatases.

Alkaline Phosphatase↗

PubMed1969

The influence of metal ions on the orthophosphatase and inorganic pyrophosphatase activities of human alkaline phosphatase.

1. The differential effects of adding Zn(2+) and Mg(2+) on the orthophosphatase and inorganic pyrophosphatase activities of human intestinal alkaline phosphatase were studied. 2. In the presence of excess of Zn(2+), inorganic pyrophosphatase activity is inhibited. At higher concentrations of pyrophosphate, hydrolysis of this substrate takes place, but is inhibited competitively by the Zn(2+)-pyrophosphate complex. This complex also acts as a competitive inhibitor of orthophosphate hydrolysis. 3. Excess of Mg(2+) also inhibits pyrophosphatase action by removal of substrate; at low concentrations, this ion activates pyrophosphatase, as is the case with orthophosphatase. 4. It is concluded that, when interactions between metal ions and pyrophosphate are taken into account, the effects of these ions are consistent with the view that alkaline phosphatases possess both orthophosphatase and inorganic pyrophosphatase activities.

Alkaline Phosphatase↗

PubMed1976

Location of nucleotide pyrophosphatase and alkaline phosphodiesterase activities on the lymphocyte surface membrane.

1. Isolated mouse spleen lymphocytes hydrolysed UDP-galactose added to the medium. Nucleotide pyrophosphatase activity that accounted for this hydrolysis was enriched to a similar extent as alkaline phosphodiesterase and 5'-nucleotidase in a lymphocyte plasma-membrane fraction. 2. The cell surfaces of mouse spleen and thymus lymphocytes were iodinated with 125I by using the lactoperoxidase-catalysis method. Detergent extracts of the cells were mixed with a purified anti-(mouse liver plasma-membrane nucleotide pyrophosphatase) antiserum and the immunoprecipitates analysed by polyacrylamide-gel electrophoresis. Only one major radioactive component, similar in size (apparent mol.wt 110000-130000) to the liver enzyme, was observed. 3. Electrophoresis of an iodinated spleen plasma-membrane fraction indicated peaks of radioactivity, including one of apparent mol.wt 110000-130000. 4. When detergent extracts of spleen lymphocytes were passed through a Sepharose-bead column containing covalently attached anti-(nucleotide pyrophosphatase) antiserum, the nucleotide pyrophosphatase activity was retained by the beads, whereas protein and leucine naphthylamidase activity were eluted. 5. The results indicate that nucleotide pyrophosphatase and alkaline phosphodiesterase activities are due to the location of the same or similar enzymes at the outer aspect of the lymphocyte plasma membrane. Some possible functions of enzymes at this location are discussed.

Animals↗

PubMed1999

Studies on the ADP-ribose pyrophosphatase subfamily of the nudix hydrolases and tentative identification of trgB, a gene associated with tellurite resistance.

Four Nudix hydrolase genes, ysa1 from Saccharomyces cerevisiae, orf209 from Escherichia coli, yqkg from Bacillus subtilis, and hi0398 from Hemophilus influenzae were amplified, cloned into an expression vector, and transformed into E. coli. The expressed proteins were purified and shown to belong to a subfamily of Nudix hydrolases active on ADP-ribose. Comparison with other members of the subfamily revealed a conserved proline 16 amino acid residues downstream of the Nudix box, common to all of the ADP-ribose pyrophosphatase subfamily. In this same region, a conserved tyrosine designates another subfamily, the diadenosine polyphosphate pyrophosphatases, while an array of eight conserved amino acids is indicative of the NADH pyrophosphatases. On the basis of these classifications, the trgB gene, a tellurite resistance factor from Rhodobacter sphaeroides, was predicted to designate an ADP-ribose pyrophosphatase. In support of this hypothesis, a highly specific ADP-ribose pyrophosphatase gene from the archaebacterium, Methanococcus jannaschii, introduced into E. coli, increased the transformant's tolerance to potassium tellurite.

Adenosine Triphosphatases↗

PubMed1962

Hydrolysis of adenosine triphosphate by crystalline yeast pyrophosphatase. Effect of zinc and magnesium ions.

Schlesinger and Coon's report that crystalline yeast inorganic pyrophosphatase, in addition to its known ability to hydrolyze inorganic pyrophosphate in the presence of Mg ions, is also able to catalyze the hydrolysis of ATP and ADP in the presence of Zn ions was confirmed. A systematic study showed that the ratio of 370 of PPase-Mg over ATPase-Zn activities per milligram protein in various preparations of pyrophosphatase obtained in the course of isolation of crystalline pyrophosphatase from baker's yeast was nearly identical in all the preparations, independent of their purity. The course of hydrolysis of ATP by crystalline pyrophosphatase in the presence of Zn was carried out with the aid of ion exchange on Dowex 1. The finding of Schlesinger and Coon that the hydrolysis proceeds from ATP to ADP and then slowly to AMP was confirmed. The kinetics of the first phase of the reaction was found to depend on the molar ratio of Zn/ATP in the reaction mixture. Mg ions in the presence of Zn ions have an accelerating effect on the rate of hydrolysis of ATP. This suggests strongly that both activities-ATPase and PPase-are manifestations of the same active group in the protein molecule of crystalline pyrophosphatase.

Adenine Nucleotides↗

PubMed1982

Kinetic studies on the interactions of two forms of inorganic pyrophosphatase of heart mitochondria with physiological ligands.

A scheme of interactions of Mg2+ ions and their 1:1 complex with PPi (PPiMg') with two forms of inorganic pyrophosphatase isolated from beef heart mitochondria has been deduced from the analysis of enzyme kinetics at pH varying from 5.6 to 8.5. The scheme implies the existence of two catalytically important metal-binding sites on the enzyme. The two enzyme forms differ in maximal velocity and affinity for the metal activator. The pH dependence of kinetic parameters suggests that the active form of the substrate is MgP2O2-7. Ca2+ ions strongly inhibit pyrophosphatase activity and the corresponding Hill coefficient is 1.5. Phosphate and ATP are weak inhibitors of pyrophosphatase of the competitive and noncompetitive type respectively. The results show that these forms of mitochondrial pyrophosphatase are similar to pyrophosphatases isolated from other sources.

Adenosine Triphosphate↗

PubMed1979

[Identification of an extracellular nucleotide pyrophosphatase in the culture media of Streptomyces mediterranei ME/R 17].

An exocellular pyrophosphatase, active on the nucleotide precursors of peptidoglycans, has been found in the culture medium of Streptomyces mediterranei ME/R 17. This enzyme was separated from the DD-carboxypeptidase by batchwise adsorption on DEAE cellulose. The pyrophosphatase had no strict substrate requirements, it hydrolyzed various UDP-sugar substrates: UDP-GlcNAc, UDP-Mur NAc and UDP-MurNAc peptides, giving rise to the corresponding sugar phosphate and to UMP. The enzyme preparation also contained a 5'-nucleotidase activity and UMP was further split to give uridine. This nucleotidase activity was inhibited by potassium tetraborate. Both cytoplasmic and particulate preparations from cells of S. mediterranei also contained a pyrophosphatase activity while only the particulate fractions showed the DD-carboxypeptidase activity. The pyrophosphatase excretion was tested during the grwoth cycle. The activity of the enzyme showed a constant increase throughout the exponential growth and a stronger increase in the late exponential phase. Such a result could be correlated with a consumption of the nutrients in the culture medium, in fact a relatively poor culture medium had a strong positive effect upon the production of the exocellular pyrophosphatase.

Borates↗

PubMed1979

Effect of nucleotides on UDP-N-acetylglucosamine pyrophosphatase and N-acetylglucosaminyltransferase activities in microsomal membranes.

Rat liver microsomes solubilized by incubating with lysolecithin or Triton X-100 showed very active UDP-N-acetylglucosamine pyrophosphatase activity leading to the hydrolysis of the substrate into N-acetylglucosamine-P and N-acetylglucosamine. ATP, GTP, CDPcholine, and CDPglucose exerted a considerable inhibitory effect on the solubilized membrane pyrophosphatase activity. CDPcholine and CDPglucose, in addition, appeared to stimulate the transfer of N-acetylglucosamine into endogenous and exogenous acceptor proteins. Evidence is also presented of an inhibitory effect of ATP (and to some extent GTP) on N-acetylglucosaminyltransferase activity. This inhibitory effect of ATP and GTP became clearly evident when the pyrophosphatase activity in the membranes was virtually eliminated in the presence of CDP-choline and CDPglucose. The effect of ATP and GTP on the solubilized membrane enzymes indicated that the inhibition of pyrophosphatase activity alone did not determine the rate of transfer of sugar to protein. The results also suggested that the UDP-N-acetylglucosamine pyrophosphatase and N-acetylglucosaminyltransferase activities were controlled independently and the effect of each nucleotide on these enzymes should, therefore, be carefully evaluated to understood its role in glycopolymer biosynthesis. Also, a possible role of choline and its derivatives in glycoprotein synthesis is discussed.

Acetylglucosamine↗

PubMed1998

Galactosyltransferase, pyrophosphatase and phosphatase activities in luminal plasma of the cauda epididymidis and in the rete testis fluid of some mammals.

Galactosyltransferase activity was measured in the luminal plasma of the cauda epididymidis of mice, rats, rabbits, rams and boars, and in the rete testis fluid of rams and boars. The activities of nucleotide pyrophosphatase and alkaline phosphatase, which compete with galactosyltransferase for substrate, were also determined. In these species, galactosyltransferase activity in the luminal plasma of the cauda epididymidis was similar when the inhibitory effect of pyrophosphatase and phosphatase was minimized by assay conditions. However, under assay conditions that did not minimize the effect of these enzymes, the galactosyltransferase activities of these species were very different and were inversely correlated with the activities of pyrophosphatase and phosphatase. The ratio of galactosyltransferase activity to pyrophosphatase and phosphatase activity was much higher in the rete testis fluid than in the luminal plasma of the cauda epididymidis in both rams and boars. In rams, galactosyltransferase in the luminal plasma of the cauda epididymidis was more heat resistant than that in serum. These results suggest that there is a species difference in the availability of galactosyltransferase activity in the luminal plasma of the cauda epididymidis and that in some species, galactosyltransferase in the luminal fluid is unlikely to have any function. The results are also discussed with respect to the possible function of galactosyltransferase, pyrophosphatase and phosphatase in epididymal luminal plasma and rete testis fluid.

Alkaline Phosphatase↗

PubMed2002

Cloning, analysis, and expression of the gene for inorganic pyrophosphatase of Aquifex pyrophilus and properties of the enzyme.

The gene encoding Aquifex pyrophilus (Apy) pyrophosphatase was cloned and sequenced. The deduced amino acid sequence of Apy pyrophosphatase showed a 94.2% homology to Aquifex aeolicus (Aae) pyrophosphatase. The gene exhibits a difference in the codon usage at the third position from Aae pyrophosphatase. The gene was expressed under the control of a tac promoter in E. coli. The recombinant Apy pyrophosphatase was purified 18.7-fold with a 52.8% yield and a specific activity of 26.2 U mg(-1) protein. The native enzyme has a homotetramer of 177 amino acids. The enzyme shows optimal activity in pH 7.5. The optimum temperature was approximately 70 degrees C. A divalent cation was absolutely required for the enzyme activity; Mg2+ was the most effective.

Amino Acid Sequence↗

PubMed1976

Properties of ecto-(inoganic) pyrophosphatase of nervous system cells in culture. Activation upon partial release of sialic acid from the cell surface.

Clonal line NN hamster astroblasts and clonal line N18 neuroblasts were treated with phospholipase C-free, protease-free, and hemolysin-free Clostridium perfringens sialidase, at a low level (5 X 10(-3) units/ml) so as to maintain cell intactness and to avoid spurious protein effects. A rapid, regular release of sialic acid was achieved. An approximately 9-fold increase in ecto-pyrophosphatase activity could be brought about by action of C. perfringens sialidase for 10 min. Since the sialidase preparations were employed at a level which gave a very low concentration of extraneous protein, and the preparations were free of demonstrable phospholipase C and protease activities, these effects appear to relate specifically to removal of cell surface sialic acid. Neutral p-nitrophenyl phosphatase was activated under the same conditions, but activity remained low compared with pyrophosphatase. Progress curves for activation of the two enzymes were dissimilar. Ecto-pyrophosphatase of NN and N18 cells had an absolute requirement for Mg2+ both before and after removal of cell surface sialic acid. In the presence of near optimum Mg2+ (5 mM), other divalent cations were inhibitory at a low level (10(-1)mM). The effect of Mg2+ concentration, as well as inorganic pyrophosphate concentration, upon ecto-pyrophosphatase activity was shown to obey Michaelis-Menten kinetics for the control activity and for the sialidase-enhanced activity of both cell types. Km for Mg2+ and for pyrophosphate remained constant upon ecto-pyrophosphatase enhancement by sialic acid removal; increase in enzymatic activity was accounted for entirely by an increase in Vmax.

Cell Line↗