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At least 19 recordsLinked to original sources

PubMed1978

Interaction of phenosafranine with nucleic acids and model polyphosphates. I. Self-aggregation and complex formation with inorganic polyphosphates.

Aggregation of phenosafranine in concentrated aqueous solutions and interaction with polyphosphates was studied by absorption and fluorescence spectroscopy. At concentrations greater than 10(-3)M phenosafranine forms dimers (Kd = 3.8 x 10(2) 1.mole-1), which are characterized by a hypsochromic shift of the visible and near ultraviolet absorption maxima accompanied by a hypochromic effect. No fluorescence could be detected from phenosafranine dimers. Analogues spectra changes were observed when a polyphosphate was titrated with phenosafranine, which indicated that with increasing saturation of the polyphosphate binding sites phenosafranine gradually became bound in the aggregated form. Full saturation of the polyphosphate binding sites with phenosafranine was reached only when an excess of free dye was present. The cooperative binding of phenosafranine to a polyphosphate could be evaluated by means of a theory proposed by Schwarz et al. At the zero ionic strength and at 25 degrees C the binding was characterized by cooperative binding constant K = 6.2 x 10(5) 1.mole-1, number of binding sites per monomeric phosphate residue g = 0.4, and cooperativity parameter q-30. Spectroscopic properties of phenosafranine in the aggregated and polyphosphate-bound states were compared with those of ethidium bromide.

Binding Sites↗

PubMedDate not supplied

[Possible physiological role of the "high molecular weight polyphosphate-polyphosphate phosphohydrolase" system in Neurospora crassa].

The biosynthesis of polyphosphatase and the system of active transport of glucose is repressed in the cells of Neurospora crassa by glucose at a high concentration. There is a strict correlation between the activity of polyphosphatase and the initial rate of glucose active transport. Both systems are repressed during the growth of the mycelium on a glucose medium and are repaired on a medium without glucose. The latter process is inhibited by cycloheximide. Under various conditions of cultivation, the ratio between the activity of polyphosphatase and the initial rate of active transport of glucose remains close to unity. The experiments with 8-azaadenine have shown that the system of active transport of glucose does not require ATP. A possible physiological role of polyphosphatase in N. crassa is discussed.

Aza Compounds↗

PubMed1976

[The possible role of high molecular weight polyphosphates in chlortetracycline biosynthesis by Streptomyces aureofaciens].

The content of condensed inorganic polyphosphates in high productive and low productive Streptomyces aureofaciens strains has been determined. At all the stages of growing the quantity of these compounds in low productive strain is 8-10-fold higher than in high productive strains. Maximum accumulation of condensed inorganic polyphosphates in both the strains Str. aureofaciens corresponds to the end of logarithmic phase of growth. In both strains the presence of two enzymes of polyphosphate biosynthesis -- ATP:polyphosphate-phosphotransferase and 1.3-diphosphoglycerate:polyphosphate-phosphotransferase has been revealed as well as the presence of the enzymes of their utilisation -- polyphosphate:D-glucose-6-phosphotransferase, polyphosphate-phosphohydrolase, tripolyphosphosphate-phosphohydrolase and pyrophosphate-phosphohydrolase. The difference in the activity of 1.3 diphosphoglycerate: polyphosphate-phosphotransferase and polyphosphate-phosphohydrolase has been revealed in both strains studied. On the basis of the data obtained it is supposed that there is a possibility of using phosphorus and energy of high molecular inorganic polyphosphate in the biosynthesis of so called products of "secondary metabolism".

Chlortetracycline↗

PubMed1977

[Polyphosphate kinase activity in yeast vacuoles].

The enzyme polyphosphate kinase (ATP: Polyphosphate phosphotransferase EC 2.7.4.1) relating to the class of transferases was detected in the vacuoles of Saccharomyces carlsbergensis yeast. The direct ATP: Polyphosphate phosphotransferase reaction resulting in the synthesis of polyphosphates from ATP was shown to occur mainly in vacuoles. The localization of the reverse polyphosphate: ADP phosphatransferase reaction was not established in any of the subcellular yeast fractions studied. The activity of the direct reaction in the yeast protoplasts makes up about 1% of the reverse one, but in vacuoles it is significantly higher and makes up to 19%. Under activation of biochemical processes involved in the production of cell wall components by protoplasts, vacuolar polyphosphates work mainly in the direction of ATP synthesis at the expense of polyphosphates accumulated in vacuoles.

Adenosine Triphosphate↗

PubMed1975

Polyphosphate levels in nongrowing cells of Saccharomyces mellis as determined by magnesium ion and the phenomenon of "Uberkompensation".

Magnesium ion enhances the maximum amount of polyphosphate that resting phosphate-starved cells of Saccharomyces mellis can store by increasing the length of time the cells will continue assimilating phosphate. The divalent cation has no effect on the rate of formation of polymer. As much as 12 times more polyphosphate is formed in cells incubated in reaction mixtures containing 0.3 M MgCl2 than in the absence of Mg2+. Potassium ion also has an influence on the amount of polyphosphate that phosphate-starved cells can accumulate but the degree of stimulation is not very large. Mg2+ and K+ have no effect on polyphosphate formation or storage in phosphate-satiated cells. Apparently, then, there are two systems for polyphosphate accumulation in S. mellis. Each system is stable in nondividing cells. The one present in phosphate-starved cells seems to be repressible by growth of the organism in media containing orthophosphate. The shift from the derepressed state to the repressed state, or vice versa, occurs only in exponentially dividing cells in appropriate media with 100% of the cells in the new physiological state by the time the cell mass has doubled. It is suggested that the word to describe the phenomenon of the accumulation of higher amounts of polyphosphate in phosphate-starved cells than the steady-state level of phosphate-satiated cells be changed from "uberkompensation" to "magnesium ubertriebung," or "magnesium enhancement."

Cell Division↗

PubMed1978

Polyphosphate-deficient mutants of Anacystis nidulans.

Polyphosphate-deficient mutants of Anacystis nidulans have been isolated by either ethyl methanesulfonate (EMS) or N-methyl nitrosoguanidine (NTG) mutagenesis and penicillin-enrichment techniques. Mutagenised stock was preincubated in a medium lacking sulfate, then transferred to a phosphate-lacking medium before penicillin treatment. Many single-colony isolates, in contrast to wild-type, show little growth in absence of phosphate, and have altered polyphosphate, and have altered polyphosphate kinase levels indicating that the lesions affect either the activity or the expression of this enzyme. In these same mutants radioactive phosphate incorporation is severely retarded. Electron micrographs confirm the absence of polyphosphate granules in some mutants.

Cyanobacteria↗

PubMed1978

[Inorganic polyphosphate metabolism in Staphylococcus aureus and the action on it of antibiotics].

The culure of Staph. aureus in the exponential growth phase contained 14-18 mg/g of dry orthophosphate biomass and 18-22 mg/g of dry acid insoluble polyphosphate biomass. The extracellular extract of the culture had a phosphohydrolase activity with respect to high molecular polyphosphates, tripolyphosphate and pyrophosphate. Penicillin and bacitracin which inhibited the biosynthesis of the cell wall had no effect on the content of polyphosphates and the phosphohydrolase activity of Staph. aureus. Heliomycin which inhibited the biosynthesis of RNA increased the content of polyphosphates by 1.5 times and decreased the content of ATP by 30 per cent in the cells of Staph. aureus.

Adenosine Triphosphate↗

PubMed1976

Role of ATP-glucokinase and polyphosphate glucokinase in Streptomyces aureofaciens.

The activity of ATP-glucokinase and of polyphosphate glucokinase was examined during growth of the actinomycete Streptomyces aureofaciens 8425 under conditions of intense chlortetracycline (CTC) synthesis. ATP-glucokinase was active in the strain only during the logarithmic phase of culture growth; the activity of polyphosphate glucokinase appears only at the end of the logarithmic phase of growth and rises in parallel with the rate of CTC biosynthesis in the stationary phase. During the rise of activity of polyphosphate glucokinase and of CTC biosynthesis the cells accumulate sugar phosphates, mainly glucose-6-phosphate. It appears that the biosynthesis of CTC in Streptomyces aureofaciens takes place at the expense of glycolysis, using up the high-energy phosphate of high-molecular polyphosphates.

Adenosine Triphosphate↗

PubMed1975

Kinetics of 99mTc-labeled pyrophosphate and polyphosphate in man.

Thekinetic of 99mTc-labeled pyrophosphate were compared with those of polyphosphate in ten patients in a combined study. Both agents cleared from the blood in a biexpoential fashion. The clearance half-time of Exponent I was the same for both and was shorter than the clearance half-time of Exponent ii. Urinary excretion of both agents was the same during the first hour but during the next 3 hr Tc-pyrophosphate cleared at a slightly more rapid rate, resulting in lower blood background radioactivity. Both agents were bound loosely to plasma proteins, mainly to globulin fractions. The sensitivity of lesion detection was similar for both. Excellent bone images were obtained with both agents. The images with Tc-pyrophosphatewere consistently superior owing to the low blood background and they took less time to accumulate an identical number of counts from identical regions. With the amount of 99mTc-complex used, no hyocalcemia or tetany was noted, nor was there any significant effect on 1-hr serum levels of inorganic phosphours and alkaline phosphatase. Four hours after injection, 9.5% of the dose of Tc-pyrophosphate was circulating in blood, 31.7% was excreted in urine, and the remaining 58.8% was taken up by bone and other tissues. The corresponding values with Tc-polyphosphate were 12.5% in blood, 29.0% in urine, and 58.5% in bone and other tissues. Among the soft tissues, the genitourinary system is most consistently visualized. It is concluded that both Tc-pyroposphate and Tc-polyphosphate are excellent skeletal-imaging agents and that Tc-pyrophosphate appears slightly superior to Tc-polyphosphate.

Blood Proteins↗

PubMed1976

Comparison of 18F and 99mTc-polyphosphate in orthopedic bone scintigraphy.

To compare 99mTc-polyphosphate and 18F for use in orthopedics, 79 patients were examined with both. Fifty cases were suitable for analysis. While the extraskeletal uptake of 18F was found to be negligible, 99mTc-polyphosphate may accumulate considerably in pathologic soft tissue, e.g., in soft-tissue tumors and in inflamed synovial tissue. This soft-tissue Tc accumulation may obscure the osseus uptake, notably in the examination of joint regions, commonly the regions of interest in orthopedics. After simultaneous administration of both agents, quantitative measurements were performed on specimens of bone and synovial tissue from diseased joints in human patients and in rabbits. The uptake of 99mTc-polyphosphate in synovial tissue was shown to be about seven times that of 18F, while their uptakes in bone were equal. In short, 99mTc-polyphosphate, a valuable tracer in general, is hardly the agent of choice in orthopedics.

Adult↗

PubMed1977

[Some pathways of biosynthesis and degradation of polyphosphates from green algae Acetabularia mediterranea].

The activity of ATP: polyphosphate phosphotransferase was detected in free-cellular extracts of Acetabularia mediterranea. The enzyme activity in cells originally deficient in phosphorus and subsequently transferred into the phosphate-containing medium increases 5-10-fold as compared to normal. Polyphosphate degradation in A. mediterranea is probably produced by polyphosphatase, which was also detected in the free-cellular extract. It was shown that the polyphosphatase activity has two pH optima, i.e. 4.5 and 7.5, and is considerably increased when the cells are transferred into the phosphate-free medium. It is assumed that high-molecular polyphosphates involved in A. Mediterranea metabolism are responsible for regulation of orthophosphate and ATP level in the cells by ATP: polyphosphate phosphotransferase and polyphosphatase.

Acetabularia↗

PubMedDate not supplied

[Relationship between the content of some fractions of high molecular weight polyphosphates and total nucleic acids upon dehydration of the yeast Saccharomyces cerevisiae].

Essential redistribution of various polyphosphate fractions was shown during dehydration and subsequent reactivation of Saccharomyces cerevisiae 14. Dehydration no matter what method was used, was followed by an increase in the content of acid soluble polyphosphates (fraction Poly P1) and a decrease of that of salt soluble polyphosphates (fraction Poly P2). Reactivation of dehydrated yeast was, on the contrary, accompanied by a decrease in the PP 1 and an increase in the Poly P2 content. A direct correlation between the Poly P2 fraction and total nucleic acids was demonstrated under various conditions of dehydration and subsequent reactivation. An inverse correlation between the content of the Poly P2, fraction and nucleic acids, on the one hand, and that of the Poly P1 fraction, on the other, was observed. Study of activities of polyphosphatases, tripolyphosphatase, pyrophosphatase and ATPase in dehydrated yeast showed values similar to those in original cells.

DNA↗

PubMed1977

[The behavior of polyphosphates during production and storage of long keeping milk products (author's transl)].

Polyphosphates added as stabilizers in the production process if liquid sterilized milk products are completely hydrolyzed to mono- and diphosphates. The diphosphate is further hydrolyzed during storage of the products. The extent of hydrolysis of diphosphate depends upon the processing conditions and may vary from production to production. During spray-drying of milk, the polyphosphates added are only partially hydrolyzed; further degradation of the polyphosphates takes place during storage.

Animals↗

PubMed1975

Purification and characterization of a polyphosphate kinase from Arthrobacter atrocyaneus.

Polyphosphate kinase, an enzyme which incorporated the gamma-phosphate of ATP into long-chain polyphosphate molecules, was purified more than 700-fold from Arthrobacter atrocyaneus by ammonium sulphate fractionation, DEAE-cellulose column chromatography and Ssphadex G-200 gel filtration. The enzyme had a broad pH optimum at 6-0 to 7-0 and required Mn2+ or Mg2+, histone, and inorganic phosphate for activity. The Km for Mn-ATP was 0-53 mM, and for inorganic phosphate was 1-67 mM. Free ATP concentrations greater than 8 muM inhibited the enzyme. Free Mn2+ or Mg2+ concentrations greater than 2 mM or 6 mM, respectively, were also inhibitory. Activity was strongly inhibited by 4 mM-ADP, 1 mM-PP1 or 20 mM-NaF. The effect of ADP might have resulted from reversing the equilibrium of the kinase reaction. The activation by phosphate ions might indicate a role for the enzyme in regulating intracellular phosphate levels or maintaining a phosphorus reserve. The level of enzymic activity in the bacteria responded to changes in inorganic phosphate concentration in the medium. Basic proteins, such as protamine, could substitute for histone as activator. Proteins such as casein or bovine serum albunim would also substitute for histone but only in the absence of inorganic phosphate. The presence of a protein might be necessary to form a complex with the product, thus preventing reversal of the reaction in vitro. The reaction product was characterized, and found to be labile in hydroxylamine, base, and acid at 100 degrees C. It behaved as a long-chain-polyphosphate molecule on chromatography in an Ebel's solvent. The enzymic activity was therefore not that of a protein kinase.

Adenosine Triphosphate↗

PubMedDate not supplied

[Polyphosphate biosynthesis in Rhodospirillum rubrum chromatophores].

The chromatophores of Rhodospirillum rubrum were found to synthesize in the light not only ATP and pyrophosphate but also high molecular weight polyphosphates. Biosynthesis of all studied compounds was inhibited by antimycin A, an inhibitor of the electron-transport photosynthetic chain. Synthesis of high molecular weight polyphosphates is stimulated, while that of pyrophosphate is inhibited, in the conditions providing intensive synthesis of ATP (in the presence of ADP and in the absence of oligomycin). The results obtained suggest that biosynthesis of high molecular weight polyphosphates is related to photosynthetic phosphorylation, via ATP but not pyrophosphate.

Adenosine Diphosphate↗

PubMed1975

[The polyphosphate synthetase of Saccharomyces cerevisiae].

The polyphosphate-synthetase, isolated from a homogenate of phosphate starved cells, catalyses the synthesis of linear polyphosphates from orthophosphate. It is localized in the membrane fraction which deposits between 400 and 1000 X g; its optimal pH is 7.1; its KM toward orthophosphate is 4.0 X 10(-4) M; ATP stimulates the reaction. The enzyme synthezises especially polyphosphates with short chain length.

Adenosine Triphosphate↗

PubMed1977

[ On the absence of high-molecular polyphosphates in chloroplasts of Acetabularia mediterranea].

High-molecular polyphosphates have been identified in a crude fraction of chloroplasts of Acetabularia mediterranea. However, after a short-term treatment of the fraction with a hypotonic salt solution and centrifugation in a sucrose density gradient it was found possible to completely separate high-molecular polyphosphates from intact chloroplasts. Consequently the chloroplasts themselves contain no high-molecular polyphosphates. It is assumed that the high-molecular polysphates found in a crude fraction of chloroplasts are constitutents of the "metachromatic" granules which can be revealed in the A. mediterranea cytoplasm by cytochemical methods.

Acetabularia↗

PubMed1978

Autoradiographic studies of fracture healing using 99Tcm-Sn-polyphosphate.

Using 99Tcm-Sn-polyphosphate, macroautoradiographs were produced of 34 standardized, medullary-nailed, 1--10-week-old tibial fractures in the rat. The radioactivity was localized in the callus and epiphyseal growth plate. On microautoradiography the 99Tcm-Sn-polyphosphate was found diffusely scattered within the mineralizing part of the callus and the epiphyseal growth plate.

Animals↗