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Results for “Pyrophosphatases”

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At least 325 records · Page 18Linked to original sources
PubMed1992

The transplacental effect of lead compounds on inorganic pyrophosphatase in brain, liver and kidneys of newborn rats.

The transplacental effect of tetraethyl lead or lead acetate on the activity of inorganic pyrophosphatase in brain, liver and kidneys of newborn rats varied with the organ, the lead compound, the dose, and the route and time of administration. Enzyme activity was usually decreased in brain and liver, suggesting adverse effects of lead on metabolism in these organs. The inorganic pyrophosphatase activity was generally increased in kidneys.

Animals↗
PubMed1977

[Inhibition of mouse spleen inorganic pyrophosphatase by methylene diphosphonic acid].

Some properties of mouse spleen cytosol inorgainc pyrophosphatase (PPi-ase) (E. C. 3.6.1.1) as well as the effect of methylene diphosphonic acid (PCP) on the PPi-ase activity were studied. Specific staining for the enzyme PAAG disc-electrophoresis was developed; it was shown that the PPi-ase formed only one band in 7.5% PAAG. The enzyme pH optimum being 8.0, the optimal [Mg++]/[PPi] ratio was about 2; Km =7.7x10(-4) M, Vmax=0.77 mkM. min-1. mg protein-1. PCP was shown to competitively inhibit the pyrophosphatase reaction, Ki=2.5x10(-4) M +/- 0.2x10(-4) M.

Animals↗
PubMed1977

Subcellular distribution and properties of alkaline inorganic pyrophosphatase of maize leaves.

1. Studies on the distribution of alkaline inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) in the subcellular fractions of maize leaves showed that the enzyme is present in cytoplasm, chloroplasts and mitochondria. The activity observed in nuclei and microsomes may result from contamination with the mitochondrial fraction. 2. Alkaline pyrophosphatases from three subcellular fractions were purified by fractionation with (NH4)2SO4, followed by ion-exchange and gel-filtration chromatography, and by isoelectric focusing. Highly purified enzyme preparations, with specific activities ranging from 55 to 188 micronmoles/min/mg protein, were obtained. 3. All the enzymes exhibited the maximum activity at pH 8.5 and the Mg2+/PPi ratio of 5. They differed in electrophoretic mobility, pI, and susceptibility to urea and thermal denaturation. This indicates that they represent isoenzymes compartmentized in particular subcellular fractions.

Cell Fractionation↗
PubMed1979

[Reconstitution of electrogenic function of pyrophosphatase isolated from Rhodospirillum rubrum membranes].

The membrane vesicles (proteoliposomes) have been reconstituted from phospholipids and inorganic pyrophosphatase (EC 3.6.1.1) isolated from Rhodospirillum rubrum chromatophores. An addition of inorganic pyrophosphate (PPi) causes a Mg2+-dependent formation of a transmembrane electric potential difference and an uptake of penetrating tetraphenylborate anions by the proteoliposomes. Thus, isolated pyrophosphatase, being incorporated into the phospholipid membrane, functions as a MgPPi-dependent protein generator of the electric current.

Cell Membrane↗
PubMed1979

The influence of growth temperature on the heat stability of inorganic pyrophosphatase from crude extracts of Bacillus stearothermophilus.

Inorganic pyrophosphatase activity of crude extracts from Bacillus stearothermophilus adapts its thermostability to the growth temperature of the cells. Magnesium ions increase the stability of the enzyme in all cases. Depending on the growth temperature of the cells two pyrophosphatase species differing in their molecular weights and heat stabilities have been detected.

Drug Stability↗
PubMed1989

[Inorganic pyrophosphatase of rat liver cytosol. Isolation and properties].

An electrophoretically homogeneous preparation of rat liver cytosolic pyrophosphatase was obtained by a combination of chromatographic methods. The enzyme molecule is made up of two identical subunits, each about 38 kD. The enzyme is activated by Mg2+ and strongly inhibited by Ca2+. Both cations are bound on a time scale of minutes. Ca2+ binding occurs in two steps. EGTA-like metal chelators activate pyrophosphatase, presumably due to the removal of trace amounts of Ca2+ from solutions.

Animals↗
PubMed1988

Characterization of an oligosaccharide-pyrophosphodolichol pyrophosphatase activity in yeast.

Use of Triton X-114 allowed us to develop a new method to separate hydrophilic oligosaccharidic material from hydrophobic oligosaccharide pyrophosphodolichols (oligosaccharide-PP-Dol). Taking advantage of this procedure we characterize, in yeast microsomal membranes, an enzymic activity that hydrolyses oligosaccharide-PP-Dol into oligosaccharidic material. H.p.l.c. analysis together with alkaline-phosphatase- and endo-N-acetyl-beta-D-glucosaminidase-susceptibility demonstrate that the oligosaccharidic released material is mainly composed of oligomannosides containing a chitobiose phosphate at the reducing end. The enzymic activity requires bivalent cations and is inhibited by pyrophosphate, NAD+ and bacitracin. As other, commercially available, pyrophosphatases have no action on lipid intermediates, the described pyrophosphatase activity appears to be the specific enzyme for oligosaccharide-PP-Dol. This enzymic splitting of the pyrophosphate bond might be the primary event in the catabolism of lipid intermediates.

Bacitracin↗
PubMed1985

Activity of 5'-nucleotidase, AMP deaminase, adenosine deaminase, acid and alkaline phosphatase and nucleotide pyrophosphatase in human thyroid.

The activity of 5'-nucleotidase, AMP deaminase, adenosine deaminase, acid phosphatase, alkaline phosphatase and nucleotide pyrophosphatase was assayed in human thyroid glands. The 5'-nucleotidase activity was higher than that of AMP deaminase which suggested that AMP undergoes degradation primarily as a result of dephosphorylation in thyroid tissue. A high acid phosphatase activity was noted as compared to that of alkaline phosphatase activity. In toxic goitre the increase in adenosine deaminase and acid phosphatase was observed together with the decrease in pyrophosphatase activity.

5'-Nucleotidase↗
PubMed1978

Covalent structural analysis of yeast inorganic pyrophosphatase.

The present paper describes the amino acid sequence analysis of the internal and COOH-terminal cyanogen bromide fragments of yeast inorganic pyrophosphatase (Sterner, R., Noyes, C., and Heinrikson, R.L. (1974) Biochemistry 13, 91-99). This information coupled with that derived from earlier structural studies of the enzyme (Sterner, R., AND Heinrikson, R.L. (1975) Arch. Biochem. Biophys. 165, 693-703) provides the complete covalent structure of the pyrophosphatase subunit. The majority of the sequence data was derived from automated Edman degradation of the intact cyanogen bromide fragments and the large tryptic peptides obtained from citraconylated derivates in which cleavages were restricted to arginyl residues. The structural determination was completed by analysis of tryptic and chymotryptic peptides from the decitraconylated fragments. The monomer peptide chain contains 285 amino acid residues and the molecular weight calculated from the sequence analysis is 32,042.

Amino Acid Sequence↗
PubMed1978

Fluorimetric characterization and influence of Cu2+ binding on the fluorescence of inorganic pyrophosphatase from baker's yeast.

The denaturation characteristics of inorganic pyrophosphatase from baker's yeast and the interaction with Cu2+ were investigated with fluorimetric methods. The position of the fluorescence emission spectrum with a maximum at 328 nm together with a quantum yield of 0.12 led to the conclusion that most of the tryptophan residues of the protein are buried in nonpolar inner regions of the molecule. The contribution of the tyrosine residues to the fluorescence of pyrophosphatase is only about 7%. Denaturation of the protein with denaturants or changes of the pH value cause a red shift of the fluorescence emission maximum. In the presence of Cu2+ ions a fluorescence quenching is observed. Thereby, a specific binding of one Cu2+ per subunit may be distinguished from further unspecific Cu2+ binding. The Cu2+ binding to the latter sites shows a time dependence according to a slow, reversible exposure of additional binding sites. This time dependent binding characteristics was also verified by following the free Cu2+ concentration with the fluorescent "metal indicator" epsilon-ADP.

Cations, Divalent↗
PubMed1977

Inorganic pyrophosphatase activity distinct from alkaline phosphatase in rat bone.

The existence of a specific inorganic pyrophosphatase (PPi ase), distinct from alkaline phosphatase in bone has been suggested but is often regarded as questionable. In the present investigation, several features of PPi ase activity have been demonstrated, which suggest that it represents an enzyme protein different from those splitting phosphomonoesters and ATP. PPi ase was largely destroyed during extraction with n-butanol, which facilitated the solubilization of alkaline phosphatase and ATP splitting enzymes and only partially destroyed acid phosphatase. Two major groups of phosphate esters and pyrophosphates splitting enzymes were separated by gel filtration from homogenates of rat bones. The first pool contained high ATP-ase and phosphomonoesterase activities, but only low activity against inorganic pyrophosphate (PPi) in the presence of MgCl2. The second pool was most active against PPi at pH 7.5 in the presence of excess MgCl2 and only slightly hydrolyzed phosphomonoesters or ATP. Immunodiffusion showed that these 2 pools contained 2 distinct proteins. It was concluded that there exists a specific inorganic pyrophosphatase distinct from phosphomonoesterases and ATP-ases in bone tissue.

Adenosine Triphosphate↗
PubMed1981

Usefulness of serum nucleotide pyrophosphatase and phosphodiesterase I activities in classifying liver disease.

Nucleotide pyrophosphatase and phosphodiesterase I activities were determined in sera from 126 patients with different types of liver disease and in two additional groups of patients with intra- and extrahepatic cholestasis, respectively. Both activities probably represent the same enzyme, and were positively correlated with alkaline phosphatase, lipoprotein X, and several other tests reflecting cholestasis. Also, we found by discriminant analysis that tests for cholestasis frequently replaced the results of both enzymes. In some groups of liver disease, nucleotide pyrophosphatase and phosphodiesterase I were correlated with the concentrations of prealbumin and albumin. The sensitivity of phosphodiesterase I (and nucleotide phosphatase) is rather low when compared with alkaline phosphatase, and we do not recommend it for use in the clinical routine. Nevertheless, it appears to be of potential value for studies on classification of liver diseases, adding information to a panel of 20 commonly used "liver tests" by appearing in some of the best four test-sets for distinguishing between groups of liver disease by discriminant analysis.

Blood Chemical Analysis↗
PubMed1982

[Effects of lipids on the activity of soluble mitochondrial pyrophosphatase and its conversion to the membrane-bound form].

The effects of lipids on the activity of soluble and membrane-bound pyrophosphatase from beef heart mitochondria were studied. An addition of total mitochondrial lipid, phosphatidyl choline, phosphatidyl ethanolamine or cardiolipin resulted in stimulation of the enzymatic activity and an increase in thermal stability of the soluble enzyme. The maximal activating effect was exerted by the total mitochondrial lipid and phosphatidyl choline. The electrophoretic data suggest that phosphatidyl choline is a component of membrane pyrophosphatase. Preincubation of the soluble enzyme with phosphatidyl choline converted the enzyme into a membrane form, which is capable to carry out the energy-dependent synthesis of PPi in submitochondrial particles.

Animals↗
PubMed1982

[Lipid dependence of the pyrophosphatase activity of microsomes from rat liver and hepatoma].

The lipid dependence of the pyrophosphatase activity of microsomes from rat liver and hepatoma was studied. Two methods were used for modification of the lipid composition of the microsomes: delipidation with organic solvents followed by relipidation with phospholipid vesicles and transformation of the microsomal lipid composition by lipid exchange proteins. In contrast to glucose 6-phosphatase, microsomal pyrophosphatase activity was found to be insensitive to modification of the membrane lipid composition by the above method. Possible causes of the different lipid dependence of various activities of microsomal glucose 6-phosphatase are discussed.

Animals↗
PubMed1982

[Interaction of terbium ions with inorganic pyrophosphatase from bakers' yeast: characterization of the binding sites].

Terbium ions bind with a 2:1 stoichiometry per subunit to inorganic pyrophosphatase from bakers' yeast (EC 3.6.1.1) as measured by an increase of terbium fluorescence. The Tb3+ inhibition of the Mg2+ activated pyrophosphate hydrolysis is caused by a competitive binding at the substrate site of the active centre. The second Mg2+ binding site--the so-called "stabilization site"--is discussed as an additional binding site for Tb3+. Thereby, Tb3+ causes also a stabilization of the enzyme against heat denaturation. The dissociation constants of the terbium-pyrophosphatase interaction are in the micromolar range.

Binding Sites↗
PubMed1982

[Investigation of the lipid dependence of pyrophosphatase activity from rat liver microsomes and hepatoma by phospholipase C].

The lipid dependence of pyrophosphatase activity was studied by treatment of liver and hepatoma microsomes with phospholipase C from Cl. perfringens and B. cereus and a subsequent incorporation of various classes of phospholipids into the delipidated microsomes. Phospholipase C hydrolysis sharply lowers the pyrophosphatase activity of liver and hepatoma microsomes. The enzyme activity is restored after introduction of phospholipids into delipidated liver microsomes, the maximal effect being achieved on incorporation of phosphatidylcholine. All the phospholipids tested exerted the same reactivation effects on the delipidated microsomes of hepatoma. However, a more complete delipidation of hepatoma microsomes by phospholipase C hydrolysis and a subsequent organic solvent extraction revealed a specific dependence of the enzyme activity on phosphatidylserine.

Animals↗