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Sample records for active inorganic phosphate

  1. Temperature dependence of active tension in mammalian (rabbit psoas) muscle fibres: effect of inorganic phosphate.

    PubMed

    Coupland, M E; Puchert, E; Ranatunga, K W

    2001-11-01

    1. The effect of added inorganic phosphate (P(i), range 3-25 mM) on active tension was examined at a range of temperatures (5-30 degrees C) in chemically skinned (0.5 % Brij) rabbit psoas muscle fibres. Three types of experiments were carried out. 2. In one type of experiment, a muscle fibre was maximally activated at low temperature (5 degrees C) and its tension change was recorded during stepwise heating to high temperature in approximately 60 s. As found in previous studies, the tension increased with temperature and the normalised tension-(reciprocal) temperature relation was sigmoidal, with a half-maximal tension at 8 degrees C. In the presence of 25 mM added P(i), the temperature for half-maximal tension of the normalised curve was approximately 5 degrees C higher than in the control. The difference in the slope was small. 3. In a second type of experiment, the tension increment during a large temperature jump (from 5 to 30 degrees C) was examined during an active contraction. The relative increase of active tension on heating was significantly higher in the presence of 25 mM added P(i) (30/5 degrees C tension ratio of 6-7) than in the control with no added P(i) (tension ratio of approximately 3). 4. In a third type of experiment, the effect on the maximal Ca(2+)-activated tension of different levels of added P(i) (3-25 mM) (and P(i) mop adequate to reduce contaminating P(i) to micromolar levels) was examined at 5, 10, 20 and 30 degrees C. The tension was depressed with increased [P(i)] in a concentration-dependent manner at all temperatures, and the data could be fitted with a hyperbolic relation. The calculated maximal tension depression in excess [P(i)] was approximately 65 % of the control at 5-10 degrees C, in contrast to a maximal depression of 40 % at 20 degrees C and 30 % at 30 degrees C. 5. These experiments indicate that the active tension depression induced by P(i) in psoas fibres is temperature sensitive, the depression becoming less marked at

  2. Timing of inorganic phosphate release modulates the catalytic activity of ATP-driven rotary motor protein

    NASA Astrophysics Data System (ADS)

    Watanabe, Rikiya; Noji, Hiroyuki

    2014-04-01

    F1-ATPase is a rotary motor protein driven by ATP hydrolysis. The rotary motion of F1-ATPase is tightly coupled to catalysis, in which the catalytic sites strictly obey the reaction sequences at the resolution of elementary reaction steps. This fine coordination of the reaction scheme is thought to be important to achieve extremely high chemomechanical coupling efficiency and reversibility, which is the prominent feature of F1-ATPase among molecular motor proteins. In this study, we intentionally change the reaction scheme by using single-molecule manipulation, and we examine the resulting effect on the rotary motion of F1-ATPase. When the sequence of the products released, that is, ADP and inorganic phosphate, is switched, we find that F1 frequently stops rotating for a long time, which corresponds to inactivation of catalysis. This inactive state presents MgADP inhibition, and thus, we find that an improper reaction sequence of F1-ATPase catalysis induces MgADP inhibition.

  3. Measurements of metabolically active inorganic phosphate in plants growing in natural and agronomic settings and under water stress. [Stromal Phosphate

    SciTech Connect

    Sharkey, T.D.

    1988-01-01

    At high rates of photosynthesis, the conflicting requirements of adenosine triphosphate (ATP) synthesis for phosphate and starch and sucrose synthesis for low phosphate, may limit the overall rate of photosynthesis. This is called feedback limitation of photosynthesis. A nonaqueous fractionation technique was used to measure stromal phosphate levels without contamination from vacuolar phosphate. Under normal conditions the stromal phosphate level was found to be 7mM. Under feedback limited photosynthesis, this value dropped to <1mM. In a related study, the effect of water stress on photosynthesis was examined. Water stress was shown to cause a decrease in total leaf photosynthesis, due not to a total loss of photosynthetic ability, but rather due to photosynthesis only occurring in patches of the leaf. Water stress was shown to cause a reduction in starch and sucrose synthesis. Since this decline can be reversed by increasing the CO{sub 2} level around the plant, this is proposed to be due to closing of stomata due to the water stress. (MHB)

  4. A Mg(2+)-dependent ecto-phosphatase activity on the external surface of Trypanosoma rangeli modulated by exogenous inorganic phosphate.

    PubMed

    Fonseca-de-Souza, André L; Dick, Claudia Fernanda; Dos Santos, André Luiz Araújo; Meyer-Fernandes, José Roberto

    2008-08-01

    In this work, we characterized a Mg(2+)-dependent ecto-phosphatase activity present in live Trypanosoma rangeli epimastigotes. This enzyme showed capacity to hydrolyze the artificial substrate for phosphatases, p-nitrophenylphosphate (p-NPP). At saturating concentration of p-NPP, half-maximal p-NPP hydrolysis was obtained with 0.23mM Mg(2+). Ca(2+) had no effect on the basal phosphatase activity, could not substitute Mg(2+) as an activator and in contrast inhibited the p-NPP hydrolysis stimulated by Mg(2+). The dependence on p-NPP concentration showed a normal Michaelis-Menten kinetics for this phosphatase activity with values of V(max) of 8.94+/-0.36 nmol p-NP x h(-1) x 10(-7) cells and apparent K(m) of 1.04+/-0.16 mM p-NPP. Mg(2+)-dependent ecto-phosphatase activity was stimulated by the alkaline pH range. Experiments using inhibitors, such as, sodium fluoride, sodium orthovanadate and ammonium molybdate, inhibited the Mg(2+)-dependent ecto-phosphatase activity. Inorganic phosphate (Pi), a product of phosphatases, inhibited reversibly in 50% this activity. Okadaic acid and microcystin-LR, specific phosphoserine/threonine phosphatase inhibitors, inhibited significantly the Mg(2+)-dependent ecto-phosphatase activity. In addition, this phosphatase activity was able to recognize as substrates only o-phosphoserine and o-phosphothreonine, while o-phosphotyrosine was not a good substrate for this phosphatase. Epimastigote forms of T. rangeli exhibit a typical growth curve, achieving the stationary phase around fifth or sixth day and the Mg(2+)-dependent ecto-phosphatase activity decreased around 10-fold with the cell growth progression. Cells maintained at Pi-deprived medium (2 mM Pi) present Mg(2+)-dependent ecto-phosphatase activity approximately threefold higher than that maintained at Pi-supplemented medium (50 mM Pi). PMID:18599005

  5. Prediction of Muscle Energy States at Low Metabolic Rates Requires Feedback Control of Mitochondrial Respiratory Chain Activity by Inorganic Phosphate

    PubMed Central

    Schmitz, Joep P. J.; Jeneson, Jeroen A. L.; van Oorschot, Joep W. M.; Prompers, Jeanine J.; Nicolay, Klaas; Hilbers, Peter A. J.; van Riel, Natal A. W.

    2012-01-01

    The regulation of the 100-fold dynamic range of mitochondrial ATP synthesis flux in skeletal muscle was investigated. Hypotheses of key control mechanisms were included in a biophysical model of oxidative phosphorylation and tested against metabolite dynamics recorded by 31P nuclear magnetic resonance spectroscopy (31P MRS). Simulations of the initial model featuring only ADP and Pi feedback control of flux failed in reproducing the experimentally sampled relation between myoplasmic free energy of ATP hydrolysis (ΔGp = ΔGpo′+RT ln ([ADP][Pi]/[ATP]) and the rate of mitochondrial ATP synthesis at low fluxes (<0.2 mM/s). Model analyses including Monte Carlo simulation approaches and metabolic control analysis (MCA) showed that this problem could not be amended by model re-parameterization, but instead required reformulation of ADP and Pi feedback control or introduction of additional control mechanisms (feed forward activation), specifically at respiratory Complex III. Both hypotheses were implemented and tested against time course data of phosphocreatine (PCr), Pi and ATP dynamics during post-exercise recovery and validation data obtained by 31P MRS of sedentary subjects and track athletes. The results rejected the hypothesis of regulation by feed forward activation. Instead, it was concluded that feedback control of respiratory chain complexes by inorganic phosphate is essential to explain the regulation of mitochondrial ATP synthesis flux in skeletal muscle throughout its full dynamic range. PMID:22470528

  6. Active removal of inorganic phosphate from cerebrospinal fluid by the choroid plexus.

    PubMed

    Guerreiro, Pedro M; Bataille, Amy M; Parker, Sonda L; Renfro, J Larry

    2014-06-01

    The P(i) concentration of mammalian cerebrospinal fluid (CSF) is about one-half that of plasma, a phenomenon also shown here in the spiny dogfish, Squalus acanthias. The objective of the present study was to characterize the possible role of the choroid plexus (CP) in determining CSF P(i) concentration. The large sheet-like fourth CP of the shark was mounted in Ussing chambers where unidirectional (33)P(i) fluxes revealed potent active transport from CSF to the blood side under short-circuited conditions. The flux ratio was 8:1 with an average transepithelial resistance of 87 ± 17.9 Ω·cm(2) and electrical potential difference of +0.9 ± 0.17 mV (CSF side positive). Active P(i) absorption from CSF was inhibited by 10 mM arsenate, 0.2 mM ouabain, Na(+)-free medium, and increasing the K(+) concentration from 5 to 100 mM. Li(+) stimulated transport twofold compared with Na(+)-free medium. Phosphonoformic acid (1 mM) had no effect on active P(i) transport. RT-PCR revealed both P(i) transporter (PiT)1 and PiT2 (SLC20 family) gene expression, but no Na(+)-P(i) cotransporter II (SLC34 family) expression, in the shark CP. PiT2 immunoreactivity was shown by immunoblot analysis and localized by immunohistochemistry in (or near) the CP apical microvillar membranes of both the shark and rat. PiT1 appeared to be localized primarily to vascular endothelial cells. Taken together, these data indicate that the CP actively removes P(i) from CSF. This process has transport properties consistent with a PiT2, Na(+)-dependent transporter that is located in the apical region of the CP epithelium. PMID:24740787

  7. Inorganic phosphate inhibits sympathetic neurotransmission in canine saphenous veins

    SciTech Connect

    Edoute, Y.; Vanhoutte, P.M.; Shepherd, J.T.

    1987-01-01

    Inorganic phosphate has been proposed as the initiator of metabolic vasodilatation in active skeletal muscle. The present study was primarily designed to determine if this substance has an inhibitory effect on adrenergic neurotransmission. Rings of canine saphenous veins were suspended for isometric tension recording in organ chambers. A comparison was made of the ability of inorganic phosphate (3 to 14 mM) to relax rings contracted to the same degree by electrical stimulation, exogenous norepinephrine, and prostaglandin F/sub 2..cap alpha../. The relaxation during electrical stimulation was significantly greater at all concentrations of phosphate. In strips of saphenous veins previously incubated with (/sup 3/H)norepinephrine, the depression of the contractile response caused by phosphate during electrical stimulated was accompanied by a significant reduction in the overflow of labeled neurotransmitter. Thus inorganic phosphate inhibits sympathetic neurotransmission and hence may have a key role in the sympatholysis in the active skeletal muscles during exercise. By contrast, in this preparation, it has a modest direct relaxing action on the vascular smooth muscle.

  8. Effects of inorganic phosphate on endothermic force generation in muscle.

    PubMed

    Ranatunga, K W

    1999-07-01

    Using a rapid (ca. 0.2 ms) laser temperature jump technique, the rate of endothermic force generation was examined in single-skinned (rabbit psoas) muscle fibres when they were exposed to different levels of inorganic phosphate (a product released during ATP hydrolysis in active muscle). The steady force is reduced by increased phosphate but the apparent rate constant of force generation induced by a standard temperature jump (from ca. 9 degrees C to ca. 12 degrees C) increases two- to threefold when the phosphate added is increased from zero to ca. 25 mM. The increase in the apparent rate constant also exhibits saturation at higher phosphate levels and the relation is hyperbolic. Detailed examination of the data, particularly in relation to our pressure release experiments, leads to a scheme for the molecular steps involved in phosphate release and force generation in active muscle fibres, where phosphate release from attached cross-bridges involves three reversible and sequentially faster molecular steps. Step one is a moderately slow, pre-force generation step that probably represents a transition of cross-bridges from non-specific to stereospecific attached states. Step two is moderately fast and represents endothermic cross-bridge force generation (temperature sensitive) and step three is a very rapid phosphate release. Such a scheme accommodates findings from a variety of different studies, including pressure perturbation experiments and other studies where the effect of phosphate on muscle force was studied. PMID:10445293

  9. PhoB Activates Escherichia coli O157:H7 Virulence Factors in Response to Inorganic Phosphate Limitation

    PubMed Central

    Chekabab, Samuel Mohammed; Jubelin, Grégory; Dozois, Charles M.; Harel, Josée

    2014-01-01

    Enterohemorrhagic Escherichia coli (EHEC), an emerging food- and water-borne hazard, is highly pathogenic to humans. In the environment, EHEC must survive phosphate (Pi) limitation. The response to such Pi starvation is an induction of the Pho regulon including the Pst system that senses Pi variation. The interplay between the virulence of EHEC, Pho-Pst system and environmental Pi remains unknown. To understand the effects of Pi deprivation on the molecular mechanisms involved in EHEC survival and virulence under Pho regulon control, we undertook transcriptome profiling of the EDL933 wild-type strain grown under high Pi and low Pi conditions and its isogenic ΔphoB mutant grown in low Pi conditions. The differentially expressed genes included 1067 Pi-dependent genes and 603 PhoB-dependent genes. Of these 131 genes were both Pi and PhoB-dependent. Differentially expressed genes that were selected included those involved in Pi homeostasis, cellular metabolism, acid stress, oxidative stress and RpoS-dependent stress responses. Differentially expressed virulence systems included the locus of enterocyte effacement (LEE) encoding the type-3 secretion system (T3SS) and its effectors, as well as BP-933W prophage encoded Shiga toxin 2 genes. Moreover, PhoB directly regulated LEE and stx2 gene expression through binding to specific Pho boxes. However, in Pi-rich medium, constitutive activation of the Pho regulon decreased LEE gene expression and reduced adherence to HeLa cells. Together, these findings reveal that EHEC has evolved a sophisticated response to Pi limitation involving multiple biochemical strategies that contribute to its ability to respond to variations in environmental Pi and to coordinating the virulence response. PMID:24710330

  10. [Regulatory mechanism of circulating inorganic phosphate].

    PubMed

    Michigami, Toshimi

    2016-02-01

    Circulating level of phosphate is altered by age and diet, and is also controlled by several hormones such as parathyroid hormone(PTH), 1,25-dihydroxyvitamin D[1,25(OH)2D]and fibroblast growth factor 23(FGF23). The main function of PTH and 1,25(OH)2D is maintaining calcium homeostasis, while FGF23 plays a central role in phosphate metabolism. PTH suppresses phosphate reabsorption in the proximal tubules to increase the renal phosphate wasting, while 1,25(OH)2D facilitates the intestinal phosphate absorption. FGF23 increases the renal phosphate wasting and reduces the production of 1,25(OH)2D. Of note, these hormones mutually regulate one another. The production of FGF23 is also regulated by various local factors. The mechanism for sensing the phosphate availability still remains unknown, and further investigation is required. PMID:26813498

  11. Inorganic Phosphate Limitation Modulates Capsular Polysaccharide Composition in Mycobacteria.

    PubMed

    van de Weerd, Robert; Boot, Maikel; Maaskant, Janneke; Sparrius, Marion; Verboom, Theo; van Leeuwen, Lisanne M; Burggraaf, Maroeska J; Paauw, Nanne J; Dainese, Elisa; Manganelli, Riccardo; Bitter, Wilbert; Appelmelk, Ben J; Geurtsen, Jeroen

    2016-05-27

    Mycobacterium tuberculosis is protected by an unusual and highly impermeable cell envelope that is critically important for the successful colonization of the host. The outermost surface of this cell envelope is formed by capsular polysaccharides that play an important role in modulating the initial interactions once the bacillus enters the body. Although the bioenzymatic steps involved in the production of the capsular polysaccharides are emerging, information regarding the ability of the bacterium to modulate the composition of the capsule is still unknown. Here, we study the mechanisms involved in regulation of mycobacterial capsule biosynthesis using a high throughput screen for gene products involved in capsular α-glucan production. Utilizing this approach we identified a group of mutants that all carried mutations in the ATP-binding cassette phosphate transport locus pst These mutants collectively exhibited a strong overproduction of capsular polysaccharides, including α-glucan and arabinomannan, suggestive of a role for inorganic phosphate (Pi) metabolism in modulating capsular polysaccharide production. These findings were corroborated by the observation that growth under low Pi conditions as well as chemical activation of the stringent response induces capsule production in a number of mycobacterial species. This induction is, in part, dependent on σ factor E. Finally, we show that Mycobacterium marinum, a model organism for M. tuberculosis, encounters Pi stress during infection, which shows the relevance of our findings in vivo. PMID:27044743

  12. Bismuth citrate in the quantification of inorganic phosphate and its utility in the determination of membrane-bound phosphatases.

    PubMed

    Cariani, L; Thomas, L; Brito, J; del Castillo, J R

    2004-01-01

    This paper describes a rapid and sensitive method to determine inorganic phosphate, even in the presence of labile organic phosphate compounds and large quantities of proteins. The method eliminates the use of sodium arsenite, a highly toxic compound, substituting bismuth citrate for it to stabilize the phosphomolybdic acid complex formed during the interaction of inorganic phosphate and molybdate reduced by ascorbic acid. This method has also been adapted to microplates and has been used to determine the activities of Na/K ATPase and alkaline phosphatase of intestinal basolateral and luminal plasma membranes. PMID:14654048

  13. DNMT1 and HDAC2 Cooperate to Facilitate Aberrant Promoter Methylation in Inorganic Phosphate-Induced Endothelial-Mesenchymal Transition

    PubMed Central

    Tan, Xiaoying; Xu, Xingbo; Zeisberg, Michael; Zeisberg, Elisabeth M.

    2016-01-01

    While phosphorus in the form of inorganic or organic phosphate is critically involved in most cellular functions, high plasma levels of inorganic phosphate levels have emerged as independent risk factor for cardiac fibrosis, cardiovascular morbidity and decreased life-expectancy. While the link of high phosphate and cardiovascular disease is commonly explained by direct cellular effects of phospho-regulatory hormones, we here explored the possibility of inorganic phosphate directly eliciting biological responses in cells. We demonstrate that human coronary endothelial cells (HCAEC) undergo an endothelial-mesenchymal transition (EndMT) when exposed to high phosphate. We further demonstrate that such EndMT is initiated by recruitment of aberrantly phosphorylated DNMT1 to the RASAL1 CpG island promoter by HDAC2, causing aberrant promoter methylation and transcriptional suppression, ultimately leading to increased Ras-GTP activity and activation of common EndMT regulators Twist and Snail. Our studies provide a novel aspect for known adverse effects of high phosphate levels, as eukaryotic cells are commonly believed to have lost phosphate-sensing mechanisms of prokaryotes during evolution, rendering them insensitive to extracellular inorganic orthophosphate. In addition, our studies provide novel insights into the mechanisms underlying specific targeting of select genes in context of fibrogenesis. PMID:26815200

  14. Lack of Control in Inorganic Phosphate Uptake by Catharanthus roseus (L.) G. Don Cells (Cytoplasmic Inorganic Phosphate Homeostasis Depends on the Tonoplast Inorganic Phosphate Transport System?).

    PubMed Central

    Sakano, K.; Yazaki, Y.; Okihara, K.; Mimura, T.; Kiyota, S.

    1995-01-01

    Inorganic phosphate (Pi) uptake by Catharanthus roseus (L.) G. Don cells was studied in relation to its apparent uncontrolled uptake using 31P-nuclear magnetic resonance spectroscopy. Kinetics of Pi uptake by the cells indicated that apparent Km and Vm were about 7 [mu]M and 20 [mu]mol g-1 fresh weight h-1, respectively. Pi uptake in Murashige-Skoog medium under different Pi concentrations and different initial cell densities followed basically the same kinetics. When supplied with abundant Pi, cells absorbed Pi at a constant rate (Vm) for the first hours and accumulated it in the vacuole. As the endogenous pool expanded, the rate of Pi uptake gradually decreased to nil. Maximum Pi accumulation was 100 to 120 [mu]mol g-1 fresh weight if cell swelling during Pi uptake (about 2-fold in cell volume) was not considered. Results indicated that (a) the rate of Pi uptake by Catharanthus cells was independent of initial cell density and was constant over a wide range of Pi concentrations (2 mM to about 10 [mu]M) unless the cells were preloaded with excess Pi, and (b) there was no apparent feedback control over the Pi uptake process in the plasma membrane to avoid Pi toxicity. The importance of the tonoplast Pi transport system in cytoplasmic Pi homeostasis is discussed. PMID:12228474

  15. Dual Mechanism of Ion Permeation through VDAC Revealed with Inorganic Phosphate Ions and Phosphate Metabolites

    PubMed Central

    Krammer, Eva-Maria; Vu, Giang Thi; Homblé, Fabrice; Prévost, Martine

    2015-01-01

    In the exchange of metabolites and ions between the mitochondrion and the cytosol, the voltage-dependent anion channel (VDAC) is a key element, as it forms the major transport pathway for these compounds through the mitochondrial outer membrane. Numerous experimental studies have promoted the idea that VDAC acts as a regulator of essential mitochondrial functions. In this study, using a combination of molecular dynamics simulations, free-energy calculations, and electrophysiological measurements, we investigated the transport of ions through VDAC, with a focus on phosphate ions and metabolites. We showed that selectivity of VDAC towards small anions including monovalent phosphates arises from short-lived interactions with positively charged residues scattered throughout the pore. In dramatic contrast, permeation of divalent phosphate ions and phosphate metabolites (AMP and ATP) involves binding sites along a specific translocation pathway. This permeation mechanism offers an explanation for the decrease in VDAC conductance measured in the presence of ATP or AMP at physiological salt concentration. The binding sites occur at similar locations for the divalent phosphate ions, AMP and ATP, and contain identical basic residues. ATP features a marked affinity for a central region of the pore lined by two lysines and one arginine of the N-terminal helix. This cluster of residues together with a few other basic amino acids forms a “charged brush” which facilitates the passage of the anionic metabolites through the pore. All of this reveals that VDAC controls the transport of the inorganic phosphates and phosphate metabolites studied here through two different mechanisms. PMID:25860993

  16. Effect of altitude on brain intracellular pH and inorganic phosphate levels

    PubMed Central

    Shi, Xian-Feng; Carlson, Paul J.; Kim, Tae-Suk; Sung, Young-Hoon; Hellem, Tracy L.; Fiedler, Kristen K.; Kim, Seong-Eun; Glaeser, Breanna; Wang, Kristina; Zuo, Chun S.; Jeong, Eun-Kee; Renshaw, Perry F.; Kondo, Douglas G.

    2015-01-01

    Normal brain activity is associated with task-related pH changes. Although central nervous system syndromes associated with significant acidosis and alkalosis are well understood, the effects of less dramatic and chronic changes in brain pH are uncertain. One environmental factor known to alter brain pH is the extreme, acute change in altitude encountered by mountaineers. However, the effect of long-term exposure to moderate altitude has not been studied. The aim of this two-site study was to measure brain intracellular pH and phosphate-bearing metabolite levels at two altitudes in healthy volunteers, using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Increased brain pH and reduced inorganic phosphate (Pi) levels were found in healthy subjects who were long-term residents of Salt Lake City, UT (4720 ft/1438 m), compared with residents of Belmont, MA (20 ft/6 m). Brain intracellular pH at the altitude of 4720 ft was more alkaline than that observed near sea level. In addition, the ratio of inorganic phosphate to total phosphate signal also shifted toward lower values in the Salt Lake City region compared with the Belmont area. These results suggest that long-term residence at moderate altitude is associated with brain chemical changes. PMID:24768210

  17. Calcium phosphate nanoparticles are associated with inorganic phosphate-induced osteogenic differentiation of rat bone marrow stromal cells.

    PubMed

    Chen, Xiao-rong; Bai, Jing; Yuan, Shuai-jun; Yu, Cai-xia; Huang, Jian; Zhang, Tian-lan; Wang, Kui

    2015-08-01

    In the present study, we demonstrated that calcium phosphate (CaP) nanoparticles formed in cell culture media were implicated in the process of high inorganic phosphate (Pi) mediated osteogenic differentiation of rat bone marrow stromal cells (BMSCs). Exposure of BMSCs in vitro to high Pi-containing media reduced alkaline phosphatase (ALP) activity and the expressions of osteoblast-specific genes. The sediments of CaP nanoparticles were observed at the cell surface and some of them were concomitantly found inside cells at high Pi concentration. In addition, treatment the cells with pyrophosphate (PPi), an inhibitor of calcium crystal formation, abrogated the ALP activity induced by high Pi, suggesting the contribution of CaP nanoparticles. Moreover, for isolated CaP nanoparticles, there was a trend of conversion from amorphous calcium phosphate to hydroxyapatite with elevated Pi. The particle size of CaP increased and the surface morphology changed from spherical to irregular due to increased concentrations of serum proteins incorporated into CaP nanoparticles. The study demonstrated that those physicochemical properties of CaP nanoparticles played an important role in modulating BMSCs differentiation. Furthermore, the addition of Pi in the osteogenic media resulted in a dose-dependent increase in matrix mineralization, while treatment of the cells with PPi suppressed Pi-induced calcium deposition. The findings indicated that calcium deposition in the matrix partly came from the spontaneous precipitation of CaP nanoparticles. PMID:26111760

  18. Insight into the short- and long-term effects of inorganic phosphate on anammox granule property.

    PubMed

    Zhang, Zheng-Zhe; Xu, Jia-Jia; Hu, Hai-Yan; Shi, Zhi-Jian; Ji, Zheng-Quan; Deng, Rui; Shi, Man-Ling; Jin, Ren-Cun

    2016-05-01

    The short- and long-term effects of inorganic phosphate on property of anaerobic ammonium oxidation (anammox) granule were investigated in this study. Acute exposure to high-level phosphate (⩾50 mM) induced the cytoplasm leakage. During a 195-day continuous-flow operation, the gradually increasing phosphate (up to 500 mgP L(-1)) slightly affected the specific anammox activity, hardly impacted the heme c content, remarkably decreased the extracellular polymeric substances production and significantly stimulated the dehydrogenase activity of anammox granules. Microbial community analysis showed no shift in the dominant anammox strain and higher population but lower relative abundance of anaerobic ammonium-oxidizing bacteria compared to the control granules. Interestingly, novel anammox granules with a hydroxyapatite core were cultivated, which possessed excellent settleability, huge granule diameter and superior mechanical strength. This study supported the application of granule-based anammox process as a pre-processing treatment in phosphate-containing and ammonia-rich wastewaters. PMID:26943933

  19. Inorganic chemically active adsorbents (ICAAs)

    SciTech Connect

    Ally, M.R.; Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  20. Inorganic phosphate export by the retrovirus receptor XPR1 in metazoans.

    PubMed

    Giovannini, Donatella; Touhami, Jawida; Charnet, Pierre; Sitbon, Marc; Battini, Jean-Luc

    2013-06-27

    Inorganic phosphate uptake is a universal function accomplished by transporters that are present across the living world. In contrast, no phosphate exporter has ever been identified in metazoans. Here, we show that depletion of XPR1, a multipass membrane molecule initially identified as the cell-surface receptor for xenotropic and polytropic murine leukemia retroviruses (X- and P-MLV), induced a decrease in phosphate export and that reintroduction of various XPR1 proteins, from fruit fly to human, rescued this defect. Inhibition of phosphate export was also obtained with a soluble ligand generated from the envelope-receptor-binding domain of X-MLV in all human cell lines tested, as well as in diverse stem cells and epithelial cells derived from renal proximal tubules, the main site of phosphate homeostasis regulation. These results provide new insights on phosphate export in metazoans and the role of Xpr1 in this function. PMID:23791524

  1. Availability of phosphorus from selected inorganic phosphate to juvenile abalone, Haliotis discus hannai ino.

    NASA Astrophysics Data System (ADS)

    Bei-Ping, Tan; Kang-Sen, Mai; Wei, Xu

    2002-06-01

    The availability of phosphorus to juvenile abalone, Haliotis discus hannai from primary, secondary and tertiary calcium phosphate, primary sodium or potassium phosphate separately or in combination was determined in a 120-day feeding trial. Seven semi-purified diets were formulated to contain relatively constant dietary phosphorus, ranging from 0.78%-0.82%. The concentrations of dietary phosphorus were presumed to be slightly below the requirement for abalone. A brown alga, Laminaria japonica, was used as a control diet. Abalone juveniles of silimar size (average weight 1.18 g; average shell length 18.74 mm) were distributed in a single-pass, flow-through system using a completely randomized design with eight treatments and three replicates each treatment. The survival ranged from 71.1% to 81.1%, and was not significantly (P>0.05) related to dietary treatment. However, the weight gain rate (41.72%-65.02%), daily increment in shell length (36.87-55.07 μm) and muscle RNA-DNA ratio (3.44-4.69) were significantly (P<0.05) affected by dietary treatment. Soft body alkaline phosphatase activity (10.9-19.8 U/g wet tissue) and carcass levels of lipid (7.71%-9.33%) and protein (46.68%-49.35%) were significantly (P<0.05) responsive to available phosphorus of the diets. Dietary treatment had significant effect (P<0.05) on concentrations of phosphorus in the whole body (WB) and soft body (SB). Apparent digestibility coefficients (45%-97%) of phosphorus were also significantly (P<0.05) different between dietary treatments. The results indicated that among these inorganic compounds, primary calcium, potassium and sodium phosphates separately or in combination could be utilized effectively by juvenile abalone as dietary phosphorus sources (availability ranging from 87%-97%). However, secondary and tertiary calcium phosphates were found to be low in availability, the values being 45% and 77%, repectively.

  2. Solubilization of insoluble inorganic phosphate by Burkholderia cepacia DA23 isolated from cultivated soil

    PubMed Central

    Song, Ok-Ryul; Lee, Seung-Jin; Lee, Yong-Seok; Lee, Sang-Cheol; Kim, Keun-Ki; Choi, Yong-Lark

    2008-01-01

    A mineral phosphate solubilizing bacterium, Burkholderia cepacia DA23 has been isolated from cultivated soils. Phosphate-solubilizing activities of the strain against three types of insoluble phosphate were quantitatively determined. When 3% of glucose concentration was used for carbon source, the strain had a marked mineral phosphate-solubilizing activity. Mineral phosphate solubilization was directly related to the pH drop by the strain. Analysis of the culture medium by high pressure liquid chromatography identified gluconic acid as the main organic acid released by Burkholderia cepacia DA23. Gluconic acid production was apparently the result of the glucose dehydrogenase activity and glucose dehydrogenase was affected by phosphate regulation. PMID:24031195

  3. Proton/Phosphate Stoichiometry in Uptake of Inorganic Phosphate by Cultured Cells of Catharanthus roseus (L.) G. Don

    PubMed Central

    Sakano, Katsuhiro

    1990-01-01

    Upon absorption of phosphate, cultured cells of Catharanthus roseus (L.) G. Don caused a rapid alkalinization of the medium in which they were suspended. The alkalinization continued until the added phosphate was completely exhausted from the medium, at which time the pH of the medium started to drop sharply toward the original pH value. Phosphate exposure caused the pH of the medium to increase from pH 3.5 to values as high as 5.8, while the rate of phosphate uptake was constant throughout (10-17 micromoles per hour per gram fresh weight). This indicates that no apparent pH optimum exists for the phosphate uptake by the cultured cells. The amount of protons cotransported with phosphate was calculated from the observed pH change up to the maximum alkalinization and the titration curve of the cell suspension. Proton/phosphate transport stoichiometry ranged from less than unity to 4 according to the amount of phosphate applied. At low phosphate doses, the stoichiometries were close to 4, while at high phosphate doses, smaller stoichiometries were observed. This suggests that, at high phosphate doses, activation of the proton pump is induced by the longer lasting proton influx acidifying the cytoplasm. The increased H+ efflux due to the proton pump could partially compensate protons taken up via the proton-phosphate cotransport system. Thus, the H+/H2PO4− stoichiometry of the cotransport is most likely to be 4. PMID:16667491

  4. Phosphorylation as a method of regulating the activity of yeast inorganic pyrophosphatase. I. Activation of inorganic pyrophosphatase under the action of ATP

    SciTech Connect

    Vener, A.V.; Nazarova, T.I.; Avaeva, S.M.

    1986-04-01

    ATP activates in a noncompetitive manner the hydrolysis of magnesium pyrophosphate catalyzed by baker's yeast inorganic pyrophosphatase. On the other hand, ATP causes a fall in the amount of pyrophosphate bound with enzyme that is formed by synthesis from phosphate, which confirms the fact of an increase in the catalytic rate constant of the enzymatic hydrolysis of pyrophosphate. The reason for the activation of the inorganic pyrophosphatase is the phosphorylation of its regulatory center under the action of ATP with the inclusion of the ..gamma..-phosphate group of the ATP in the protein.

  5. The role of inorganic phosphate in the regulation of C4 photosynthesis.

    PubMed

    Iglesias, A A; Plaxton, W C; Podestá, F E

    1993-03-01

    Inorganic phosphate participates in many fundamental processes within the plant cell. Its broad influence on plant metabolism is related to such key operations as metabolite transport, enzyme regulation and carbohydrate metabolism in general. This review discusses these topics with special emphasis on the role assigned to this ubiquitous anion within the C4 pathway of photosynthesis. PMID:24318750

  6. On the effect of the injection of potassium phosphate in vivo inducing the precipitation of serum calcium with inorganic phosphate

    PubMed Central

    Soares, Alcimar B; Ticianeli, José G; Soares, Letícia B M; Amaro, George

    2013-01-01

    High concentrations of inorganic phosphate (Pi) resulted from the hydrolysis of ATP is strongly associated to the weakness of the contractile mechanism of muscles due to its attractiveness to calcium. The majority of the experiments to study such effect are conducted in vitro. This work investigates the effects of different concentrations of Pi, induced by the injection of potassium phosphate in live animals, in the precipitation with serum calcium and the generation of calcium phosphate composites. The experiments were also designed to find out the ideal amount of potassium phosphate to induce an effective reaction. Potassium phosphate was injected in Wistar rats, randomly separated and distributed into seven groups. Group I was injected with 0.5 ml of saline solution (control) and groups II through VII were injected with 0.5, 1.5, 2.5, 5.0, 7.5 and 10.0 mg/kg of potassium phosphate, respectively. Blood collected from the inferior vena cava was submitted to biochemical analyses to measure the concentrations of calcium, Pi, urea and creatinine. The results showed that Pi, induced by the injection of potassium phosphate in live animals, causes precipitation with serum calcium, with statistically significant differences between the control and the treatment groups for doses up to 5.0 mg/kg. No statistically significant differences were found between the different doses and the concentration of urea and creatinine in the plasma. We conclude that potassium phosphate can be used to induce serum calcium precipitation in-vivo, with minor effects on other physiological variables, and the ideal dose to do so is 5.0 mg/kg. PMID:24379908

  7. Nitric oxide induces the alternative oxidase pathway in Arabidopsis seedlings deprived of inorganic phosphate

    PubMed Central

    Royo, Beatriz; Moran, Jose F.; Ratcliffe, R. George; Gupta, Kapuganti J.

    2015-01-01

    Phosphate starvation compromises electron flow through the cytochrome pathway of the mitochondrial electron transport chain, and plants commonly respond to phosphate deprivation by increasing flow through the alternative oxidase (AOX). To test whether this response is linked to the increase in nitric oxide (NO) production that also increases under phosphate starvation, Arabidopsis thaliana seedlings were grown for 15 d on media containing either 0 or 1mM inorganic phosphate. The effects of the phosphate supply on growth, the production of NO, respiration, the AOX level and the production of superoxide were compared for wild-type (WT) seedlings and the nitrate reductase double mutant nia. Phosphate deprivation increased NO production in WT roots, and the AOX level and the capacity of the alternative pathway to consume electrons in WT seedlings; whereas the same treatment failed to stimulate NO production and AOX expression in the nia mutant, and the plants had an altered growth phenotype. The NO donor S-nitrosoglutathione rescued the growth phenotype of the nia mutants under phosphate deprivation to some extent, and it also increased the respiratory capacity of AOX. It is concluded that NO is required for the induction of the AOX pathway when seedlings are grown under phosphate-limiting conditions. PMID:26163703

  8. The inhibition of mitochondrial dicarboxylate transport by inorganic phosphate, some phosphate esters and some phosphonate compounds.

    PubMed

    Johnson, R N; Chappell, J B

    1974-02-01

    1. P(i) competitively inhibited succinate oxidation by intact uncoupled mitochondria in the presence of sufficient N-ethylmaleimide to block the phosphate carrier, with a K(i) of 2.5mm. 2. Of a large number of phosphate esters and phosphonate compounds, phenyl phosphate and phenylphosphonate were found to inhibit competitively uncoupled succinate oxidation by intact but not broken mitochondria. By comparison, benzoate was a relatively weak competitive inhibitor of succinate oxidation by intact mitochondria but a relatively potent inhibitor of succinate dehydrogenase. 3. Phenyl phosphate and phenylphosphonate were non-penetrant, and inhibited P(i)-dependent swelling of mitochondria suspended in isosmolar ammonium malate in a manner non-competitive with P(i). The inhibitors did not affect mitochondrial swelling when tested with P(i) alone. 4. It is concluded that: (i) phenyl phosphate and phenylphosphonate behaved as non-penetrant analogues of P(i), since their inhibitory properties were in strict contrast with those of benzoate; (ii) phenyl phosphate and phenylphosphonate interacted with the dicarboxylate carrier but not with the phosphate carrier; (iii) P(i) was effective as a competitive inhibitor of succinate oxidation because of its being either an alternative substrate for the dicarboxylate carrier or competitive with succinate for the intramitochondrial cations as proposed by Harris & Manger (1968). PMID:4822730

  9. Angiogenesis in calcium phosphate scaffolds by inorganic copper ion release.

    PubMed

    Barralet, Jake; Gbureck, Uwe; Habibovic, Pamela; Vorndran, Elke; Gerard, Catherine; Doillon, Charles J

    2009-07-01

    Angiogenesis in a tissue-engineered device may be induced by incorporating growth factors (e.g., vascular endothelial growth factor [VEGF]), genetically modified cells, and=or vascular cells. It represents an important process during the formation and repair of tissue and is essential for nourishment and supply of reparative and immunological cells. Inorganic angiogenic factors, such as copper ions, are therefore of interest in the fields of regenerative medicine and tissue engineering due to their low cost, higher stability, and potentially greater safety compared with recombinant proteins or genetic engineering approaches. The purpose of this study was to compare tissue responses to 3D printed macroporous bioceramic scaffolds implanted in mice that had been loaded with either VEGF or copper sulfate. These factors were spatially localized at the end of a single macropore some 7 mm from the surface of the scaffold. Controls without angiogenic factors exhibited only poor tissue growth within the blocks; in contrast, low doses of copper sulfate led to the formation of microvessels oriented along the macropore axis. Further, wound tissue ingrowth was particularly sensitive to the quantity of copper sulfate and was enhanced at specific concentrations or in combination with VEGF. The potential to accelerate and guide angiogenesis and wound healing by copper ion release without the expense of inductive protein(s) is highly attractive in the area of tissue-engineered bone and offers significant future potential in the field of regenerative biomaterials. PMID:19182977

  10. Availability of phosphorus from selected inorganic phosphate to juvenile abalone, Haliotis discus hannai ino.

    NASA Astrophysics Data System (ADS)

    Tan, Bei-Ping; Mai, Kang-Sen; Xu, Wei

    2002-06-01

    The availability of phosphorus to juvenile abalone, Haliotis discus hannai from primary, secondary and tertiary calcium phosphate, primary sodium or potassium phosphate separately or in combination was determined in a 120-day feeding trial. Seven semi-purified diets were formulated to contain relatively constant dietary phosphorus, ranging from 0.78% 0.82%. The concentrations of dietary phosphorus were presumed to be slightly below the requirement for abalone. A brown alga, Laminaria japonica, was used as a control diet. Abalone juveniles of silimar size (average weight 1.18 g; average shell length 18.74 mm) were distributed in a single-pass, flow-through system using a completely randomized design with eight treatments and three replicates each treatment. The survival ranged from 71.1% to 81.1%, and was not significantly (P>0.05) related to dietary treatment. However, the weight gain rate (41.72% 65.02%), daily increment in shell length (36.87 55.07 μm) and muscle RNA-DNA ratio (3.44 4.69) were significantly (P<0.05) affected by dietary treatment. Soft body alkaline phosphatase activity (10.9 19.8 U/g wet tissue) and carcass levels of lipid (7.71% 9.33%) and protein (46.68% 49.35%) were significantly (P<0.05) responsive to available phosphorus of the diets. Dietary treatment had significant effect (P<0.05) on concentrations of phosphorus in the whole body (WB) and soft body (SB). Apparent digestibility coefficients (45% 97%) of phosphorus were also significantly (P<0.05) different between dietary treatments. The results indicated that among these inorganic compounds, primary calcium, potassium and sodium phosphates separately or in combination could be utilized effectively by juvenile abalone as dietary phosphorus sources (availability ranging from 87% 97%). However, secondary and tertiary calcium phosphates were found to be low in availability, the values being 45% and 77%, repectively.

  11. A precise method for the analysis of d18O of dissolved inorganic phosphate in seawater

    USGS Publications Warehouse

    McLaughlin, K.; Silva, S.; Kendall, C.; Stuart-Williams, Hilary; Paytan, A.

    2004-01-01

    A method for preparation and analysis of the oxygen isotope composition (d18O) of dissolved inorganic phosphate (DIP) has been developed and preliminary results for water samples from various locations are reported. Phosphate is extracted from seawater samples by coprecipitation with magnesium hydroxide. Phosphate is further purified through a series of precipitations and resin separation and is ultimately converted to silver phosphate. Silver phosphate samples are pyrolitically decomposed to carbon monoxide and analyzed for d18O. Silver phosphate samples weighing 0.7 mg (3.5 mol oxygen) can be analyzed routinely with an average standard deviation of about 0.3. There is no isotope fractionation during extraction and blanks are negligible within analytical error. Reproducibility was determined for both laboratory standards and natural samples by multiple analyses. A comparison between filtered and unfiltered natural seawater samples was also conducted and no appreciable difference was observed for the samples tested. The d18O values of DIP in seawater determined using this method range from 18.6 to 22.3, suggesting small but detectable natural variability in seawater. For the San Francisco Bay estuary DIP d18O is more variable, ranging from 11.4 near the San Joaquin River to 20.1 near the Golden Gate Bridge, and was well correlated with salinity, phosphate concentration, and d18O of water.

  12. [Calorimetric assay of yeast inorganic pyrophosphatase interaction with magnesium and phosphate ions].

    PubMed

    Vorob'eva, N N; Nazarova, T I; Bakuleva, N P; Avaeva, S M; Protasevich, I I

    1982-05-01

    The thermodynamic characteristics for the specific binding of one or two Mg2+ by the yeast inorganic pyrophosphatase and for the enzyme interaction with phosphate were determined. Saturation of the first binding site with Mg2+ causes structural rearrangements in the enzyme molecule without changing the temperature of protein denaturation. On the contrast, saturation of the second binding site results in stabilization of the system, i. e. a considerable fall in the entropy and a rise in the temperature of denaturation. Phosphorylation of the enzyme carboxylic group by inorganic phosphate requires saturation of the first binding site with Mg2+ and is not accompanied by changes in the enthalpy of the system. The pyrophosphate synthesis in the presence of the enzyme saturated with Mg2+ in both binding sites is associated with changes in the enthalpy and, possibly, in the entropy of the system. PMID:6124280

  13. Controlled formation of calcium-phosphate-based hybrid mesocrystals by organic-inorganic co-assembly.

    PubMed

    Zhai, Halei; Chu, Xiaobin; Li, Li; Xu, Xurong; Tang, Ruikang

    2010-11-01

    An understanding of controlled formation of biomimetic mesocrystals is of great importance in materials chemistry and engineering. Here we report that organic-inorganic hybrid plates and even mesocrystals can be conveniently synthesized using a one-pot reaction in a mixed system of protein (bovine serum albumin (BSA)), surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)) and supersaturated calcium phosphate solution. The morphologies of calcium-phosphate-based products are analogous to the general inorganic crystals but they have abnormal and interesting substructures. The hybrids are constructed by the alternate stacking of organic layer (thickness of 1.31 nm) and well-crystallized inorganic mineral layer (thickness of 2.13 nm) at the nanoscale. Their morphologies (spindle, rhomboid and round) and sizes (200 nm-2 μm) can be tuned gradually by changing BSA, AOT and calcium phosphate concentrations. This modulation effect can be explained by a competition between the anisotropic and isotropic assembly of the ultrathin plate-like units. The anisotropic assembly confers mesocrystal characteristics on the hybrids while the round ones are the results of isotropic assembly. However, the basic lamellar organic-inorganic substructure remains unchanged during the hybrid formation, which is a key factor to ensure the self-assembly from molecule to micrometre scale. A morphological ternary diagram of BSA-AOT-calcium phosphate is used to describe this controlled formation process, providing a feasible strategy to prepare the required materials. This study highlights the cooperative effect of macromolecule (frame structure), small biomolecule (binding sites) and mineral phase (main component) on the generation and regulation of biomimetic hybrid mesocrystals. PMID:20944837

  14. Controlled formation of calcium-phosphate-based hybrid mesocrystals by organic-inorganic co-assembly

    NASA Astrophysics Data System (ADS)

    Zhai, Halei; Chu, Xiaobin; Li, Li; Xu, Xurong; Tang, Ruikang

    2010-11-01

    An understanding of controlled formation of biomimetic mesocrystals is of great importance in materials chemistry and engineering. Here we report that organic-inorganic hybrid plates and even mesocrystals can be conveniently synthesized using a one-pot reaction in a mixed system of protein (bovine serum albumin (BSA)), surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)) and supersaturated calcium phosphate solution. The morphologies of calcium-phosphate-based products are analogous to the general inorganic crystals but they have abnormal and interesting substructures. The hybrids are constructed by the alternate stacking of organic layer (thickness of 1.31 nm) and well-crystallized inorganic mineral layer (thickness of 2.13 nm) at the nanoscale. Their morphologies (spindle, rhomboid and round) and sizes (200 nm-2 μm) can be tuned gradually by changing BSA, AOT and calcium phosphate concentrations. This modulation effect can be explained by a competition between the anisotropic and isotropic assembly of the ultrathin plate-like units. The anisotropic assembly confers mesocrystal characteristics on the hybrids while the round ones are the results of isotropic assembly. However, the basic lamellar organic-inorganic substructure remains unchanged during the hybrid formation, which is a key factor to ensure the self-assembly from molecule to micrometre scale. A morphological ternary diagram of BSA-AOT-calcium phosphate is used to describe this controlled formation process, providing a feasible strategy to prepare the required materials. This study highlights the cooperative effect of macromolecule (frame structure), small biomolecule (binding sites) and mineral phase (main component) on the generation and regulation of biomimetic hybrid mesocrystals.

  15. Heat Stress Affects Pi-related Genes Expression and Inorganic Phosphate Deposition/Accumulation in Barley.

    PubMed

    Pacak, Andrzej; Barciszewska-Pacak, Maria; Swida-Barteczka, Aleksandra; Kruszka, Katarzyna; Sega, Pawel; Milanowska, Kaja; Jakobsen, Iver; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2016-01-01

    Phosphorus (P) in plants is taken from soil as an inorganic phosphate (Pi) and is one of the most important macroelements in growth and development. Plants actively react to Pi starvation by the induced expression of Pi transporters, MIR399, MIR827, and miR399 molecular sponge - IPS1 genes and by the decreased expression of the ubiquitin-conjugating enzyme E2 (PHOSPHATE2 - PHO2) and Pi sensing and transport SPX-MFS genes. The PHO2 protein is involved in the degradation of Pi transporters PHT1;1 (from soil to roots) and PHO1 (from roots to shoots). The decreased expression of PHO2 leads to Pi accumulation in shoots. In contrast, the pho1 mutant shows a decreased level of Pi concentration in shoots. Finally, Pi starvation leads to decreased Pi concentration in all plant tissues. Little is known about plant Pi homeostasis in other abiotic stress conditions. We found that, during the first hour of heat stress, Pi accumulated in barley shoots but not in the roots, and transcriptomic data analysis as well as RT-qPCR led us to propose an explanation for this phenomenon. Pi transport inhibition from soil to roots is balanced by lower Pi efflux from roots to shoots directed by the PHO1 transporter. In shoots, the PHO2 mRNA level is decreased, leading to an increased Pi level. We concluded that Pi homeostasis in barley during heat stress is maintained by dynamic changes in Pi-related genes expression. PMID:27446155

  16. Heat Stress Affects Pi-related Genes Expression and Inorganic Phosphate Deposition/Accumulation in Barley

    PubMed Central

    Pacak, Andrzej; Barciszewska-Pacak, Maria; Swida-Barteczka, Aleksandra; Kruszka, Katarzyna; Sega, Pawel; Milanowska, Kaja; Jakobsen, Iver; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2016-01-01

    Phosphorus (P) in plants is taken from soil as an inorganic phosphate (Pi) and is one of the most important macroelements in growth and development. Plants actively react to Pi starvation by the induced expression of Pi transporters, MIR399, MIR827, and miR399 molecular sponge – IPS1 genes and by the decreased expression of the ubiquitin-conjugating enzyme E2 (PHOSPHATE2 – PHO2) and Pi sensing and transport SPX-MFS genes. The PHO2 protein is involved in the degradation of Pi transporters PHT1;1 (from soil to roots) and PHO1 (from roots to shoots). The decreased expression of PHO2 leads to Pi accumulation in shoots. In contrast, the pho1 mutant shows a decreased level of Pi concentration in shoots. Finally, Pi starvation leads to decreased Pi concentration in all plant tissues. Little is known about plant Pi homeostasis in other abiotic stress conditions. We found that, during the first hour of heat stress, Pi accumulated in barley shoots but not in the roots, and transcriptomic data analysis as well as RT-qPCR led us to propose an explanation for this phenomenon. Pi transport inhibition from soil to roots is balanced by lower Pi efflux from roots to shoots directed by the PHO1 transporter. In shoots, the PHO2 mRNA level is decreased, leading to an increased Pi level. We concluded that Pi homeostasis in barley during heat stress is maintained by dynamic changes in Pi-related genes expression. PMID:27446155

  17. Uptake of inorganic phosphate is a limiting factor for Saccharomyces cerevisiae during growth at low temperatures.

    PubMed

    Vicent, Isabel; Navarro, Alfonso; Mulet, Jose M; Sharma, Sukesh; Serrano, Ramón

    2015-05-01

    The fermenting ability of Saccharomyces at low temperatures is crucial for the development of alcoholic beverages, but the key factors for the cold tolerance of yeast are not well known. In this report, we present the results of a screening for genes able to confer cold tolerance by overexpression in a laboratory yeast strain auxotrophic for tryptophan. We identified genes of tryptophan permeases (TAT1 and TAT2), suggesting that the first limiting factor in the growth of tryptophan auxotrophic yeast at low temperatures is tryptophan uptake. This fact is of little relevance to industrial strains which are prototrophic for tryptophan. Then, we screened for genes able to confer growth at low temperatures in tryptophan-rich media and found several genes related to phosphate uptake (PHO84, PHO87, PHO90 and GTR1). This suggests that without tryptophan limitation, uptake of inorganic phosphate becomes the limiting factor. We have found that overexpression of the previously uncharacterized ORF YCR015c/CTO1 increases the uptake of inorganic phosphate. Also, genes involved in ergosterol biosynthesis (NSG2) cause improvement of growth at 10°C, dependent on tryptophan uptake, while the gluconeogenesis gene PCK1 and the proline biosynthesis gene PRO2 cause an improvement in growth at 10°C, independent of tryptophan and phosphate uptake. PMID:25725023

  18. The essential activated carboxyl group of inorganic pyrophosphatase.

    PubMed

    Avaeva, S M; Bakuleva, N P; Baratova, L A; Nazarova, T I; Fink, N Y

    1977-05-12

    1. A carboxyl group of high reactivity has been found in inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) from yeast. This group interacts with agents which react neither with carboxyl groups of low molecular weight compounds nor with other carboxyl groups of the protein. 2. The reaction of this activated carboxyl group with inorganic phosphate, hydroxylamine, N-methyl- and O-methylhydroxylamines, and glycine methyl ester has been studied. 3. Homoserine and homoserine lactone were found in the hydrolyzate of phosphorylated and NaBH4-reduced pyrophosphatase, indicating that an aspartyl residue is phosphorylated. 4. Hydroxylamine and other nucleophilic agents cause inactivation of pyrophosphatase as a result of interaction with a carboxyl group. Both diaminobutyric and diaminopropionic acids were seen in the acid hydrolyzate of the protein treated with hydroxylamine and subjected to rearrangement in the presence of carbodiimide. 5. The ways in which the activation of a carboxyl group in the enzyme is achieved and the presumed mechanism of action of inorganic pyrophosphatase are discussed. PMID:16652

  19. Evaluation of a low temperature hardening Inorganic Phosphate Cement for high-temperature applications

    SciTech Connect

    Alshaaer, M.; Cuypers, H.; Mosselmans, G.; Rahier, H.; Wastiels, J.

    2011-01-15

    Phase and mechanical changes of Inorganic Phosphate Cement (IPC) are identified along with changes in macro properties as functions of temperature and time. In addition to amorphous phases, the presence of significant amounts of brushite and wollastonite in the reference IPC is confirmed using X-ray diffraction. The thermal behavior of IPC up to 1000 {sup o}C shows that contraction of the solid phase in IPC due to chemical transformations causes reduction in the volume of the material. Also the ongoing meta-stable calcium phosphate transformations and reactions over a long time contribute significantly to the phase instability of the material at ambient conditions. It is found that the strength of IPC increases with ageing at ambient conditions but the formation microcracks below 105 {sup o}C causes a sharp reduction in the mechanical performance of IPC. According to the results obtained by Mercury intrusion porosimetry, the pore system of the reference IPC is dominated by mesopores.

  20. The Interplay between Inorganic Phosphate and Amino Acids determines Zinc Solubility in Brain Slices

    PubMed Central

    Rumschik, Sean M.; Nydegger, Irma; Zhao, Jinfu; Kay, Alan R

    2009-01-01

    Inorganic phosphate (Pi) is an important polyanion needed for ATP synthesis and bone formation. Since it is found at millimolar levels in plasma it is usually incorporated as a constituent of artificial cerebrospinal fluid (ACSF) formulations for maintaining brain slices. In this paper we show that Pi limits the extracellular zinc concentration by inducing metal precipitation. We present data suggesting that amino acids like histidine may counteract the Pi-induced zinc precipitation by the formation of soluble zinc complexes. We propose that the interplay between Pi and amino acids in the extracellular space may influence the availability of metals for cellular uptake. PMID:19183267

  1. Inorganic phosphate accumulation and cadmium detoxification in Klebsiella aerogenes NCTC 418 growing in continuous culture

    SciTech Connect

    Aiking, H.; Stijnman, A.; van Garderen, C.; van Heerikhuizen, H.; van Riet, J.

    1984-02-01

    Klebsiella aerogenes NCTC-418, growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture, exhibits two different cadmium detoxifying mechanisms. In addition to sulfide formation, increased accumulation of P/sub i/ is demonstrated as a novel mechanism. Intracellular cadmium is always quantitatively counterbalanced by a concerted increase in both inorganic sulfide and P/sub i/ contents of the cells. This led to the conclusion that production of sulfide and accumulation of P/sub i/ are detoxification mechanisms present in K. aerogenes but that their relative importance is crucially dependent on the strain and the growth conditions employed.

  2. Inorganic phosphate promotes redox cycling of iron in liver microsomes: effects on free radical reactions.

    PubMed

    Reinke, L A; Moore, D R; Rau, J M; McCay, P B

    1995-02-01

    The phosphate buffer concentration used in spin trapping experiments with liver microsomes markedly influenced rates of free radical formation from ethanol and dimethylsulfoxide, but not from carbon tetrachloride. Effects of phosphate concentration on ethanol radical formation were abolished by addition of deferoxamine or bathophenanthrolene, indicating that an iron-phosphate complex might be involved. High concentrations of phosphate stimulated rates of microsomal Fe+3 reduction and facilitated the mobilization of microsomal nonheme iron, but had little effect on a variety of microsomal monooxygenase enzyme activities. Although microsomal oxygen utilization and superoxide production were relatively unaffected by phosphate, hydrogen peroxide concentrations were markedly decreased in the presence of high concentrations of phosphate. Taken together, the data suggest that a ferric-phosphate complex may be enzymatically reduced by microsomal enzymes and NADPH. Reoxidation of ferrous ion is nonenzymatically promoted by phosphate and/or H2O2 produced by the microsomes. During the process of reoxidation, one or more oxidizing intermediates may be formed which initiate secondary free radical reactions. Although the reactivity of the intermediate(s) is similar to that of the hydroxyl radical, no spin trapping evidence was obtained to support this assignment. PMID:7864631

  3. Faropenem Transport across the Renal Epithelial Luminal Membrane via Inorganic Phosphate Transporter Npt1

    PubMed Central

    Uchino, Hiroshi; Tamai, Ikumi; Yabuuchi, Hikaru; China, Kayoko; Miyamoto, Ken-ichi; Takeda, Eiji; Tsuji, Akira

    2000-01-01

    We previously showed that the mouse inorganic phosphate transporter Npt1 operates in the hepatic sinusoidal membrane transport of anionic drugs such as benzylpenicillin and mevalonic acid. In the present study, the mechanism of renal secretion of penem antibiotics was examined by using a Xenopus oocyte expression system. Faropenem (an oral penem antibiotic) was transported via Npt1 with a Michaelis-Menten constant of 0.77 ± 0.34 mM in a sodium-independent but chloride ion-sensitive manner. When the concentration of chloride ions was increased, the transport activity of faropenem by Npt1 was decreased. Since the concentration gradient of chloride ions is in the lumen-to-intracellular direction, faropenem is expected to be transported from inside proximal tubular cells to the lumen. So, we tested the release of faropenem from Xenopus oocytes. The rate of efflux of faropenem from Npt1-expressing oocytes was about 9.5 times faster than that from control water-injected Xenopus oocytes. Faropenem transport by Npt1 was significantly inhibited by β-lactam antibiotics such as benzylpenicillin, ampicillin, cephalexin, and cefazolin to 24.9, 40.5, 54.4, and 26.2% of that for the control, respectively. Zwitterionic β-lactam antibiotics showed lesser inhibitory effects on faropenem uptake than anionic derivatives, indicating that Npt1 preferentially transports anionic compounds. Other anionic compounds, such as indomethacin and furosemide, and the anion transport inhibitor 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid significantly inhibited faropenem uptake mediated by Npt1. In conclusion, our results suggest that Npt1 participates in the renal secretion of penem antibiotics. PMID:10681320

  4. Faropenem transport across the renal epithelial luminal membrane via inorganic phosphate transporter Npt1.

    PubMed

    Uchino, H; Tamai, I; Yabuuchi, H; China, K; Miyamoto, K; Takeda, E; Tsuji, A

    2000-03-01

    We previously showed that the mouse inorganic phosphate transporter Npt1 operates in the hepatic sinusoidal membrane transport of anionic drugs such as benzylpenicillin and mevalonic acid. In the present study, the mechanism of renal secretion of penem antibiotics was examined by using a Xenopus oocyte expression system. Faropenem (an oral penem antibiotic) was transported via Npt1 with a Michaelis-Menten constant of 0.77 +/- 0.34 mM in a sodium-independent but chloride ion-sensitive manner. When the concentration of chloride ions was increased, the transport activity of faropenem by Npt1 was decreased. Since the concentration gradient of chloride ions is in the lumen-to-intracellular direction, faropenem is expected to be transported from inside proximal tubular cells to the lumen. So, we tested the release of faropenem from Xenopus oocytes. The rate of efflux of faropenem from Npt1-expressing oocytes was about 9.5 times faster than that from control water-injected Xenopus oocytes. Faropenem transport by Npt1 was significantly inhibited by beta-lactam antibiotics such as benzylpenicillin, ampicillin, cephalexin, and cefazolin to 24.9, 40. 5, 54.4, and 26.2% of that for the control, respectively. Zwitterionic beta-lactam antibiotics showed lesser inhibitory effects on faropenem uptake than anionic derivatives, indicating that Npt1 preferentially transports anionic compounds. Other anionic compounds, such as indomethacin and furosemide, and the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid significantly inhibited faropenem uptake mediated by Npt1. In conclusion, our results suggest that Npt1 participates in the renal secretion of penem antibiotics. PMID:10681320

  5. Inorganic phosphate in the development and treatment of cancer: A Janus Bifrons?

    PubMed

    Sapio, Luigi; Naviglio, Silvio

    2015-12-10

    Inorganic phosphate (Pi) is an essential nutrient to living organisms. It is required as a component of the energy metabolism, kinase/phosphatase signaling and in the formation and function of lipids, carbohydrates and nucleic acids and, at systemic level, it plays a key role for normal skeletal and dentin mineralization. Pi represents an abundant dietary element and its intestinal absorption is efficient, minimally regulated and typically extends to approximately 70%. Maintenance of proper Pi homeostasis is a critical event and serum Pi level is maintained within a narrow range through an elaborate network of humoral interactions and feedback loops involving intestine, kidney, parathyroid gland and bone, and depends on the activity of a number of hormones, including parathyroid hormone, 1,25-dihydroxy vitamin D, and fibroblast growth factor 23 as major regulators of Pi homeostasis. Notably, Pi intake seemingly continues to increase as a consequence of chronic high-phosphorus (P) diets deriving from the growing consumption of highly processed foods, especially restaurant meals, fast foods, and convenience foods. Several recent reports have generated significant associations between high-P intake or high-serum Pi concentration and morbidity and mortality. Many chronic diseases, including cardiovascular diseases, obesity and even cancer have been proposed to be associated with high-P intakes and high-serum Pi concentrations. On the other hand, there is also evidence that Pi can have antiproliferative effects on some cancer cell types, depending on cell status and genetic background and achieve additive cytotoxic effects when combined with doxorubicin, illustrating its potential for clinical applications and suggesting that up-regulating Pi levels at local sites for brief times, might contribute to the development of novel and cheap modalities for therapeutic intervention in some tumours. Overall, the influence of Pi on cell function and the possible relationship to

  6. Inorganic phosphate in the development and treatment of cancer: A Janus Bifrons?

    PubMed Central

    Sapio, Luigi; Naviglio, Silvio

    2015-01-01

    Inorganic phosphate (Pi) is an essential nutrient to living organisms. It is required as a component of the energy metabolism, kinase/phosphatase signaling and in the formation and function of lipids, carbohydrates and nucleic acids and, at systemic level, it plays a key role for normal skeletal and dentin mineralization. Pi represents an abundant dietary element and its intestinal absorption is efficient, minimally regulated and typically extends to approximately 70%. Maintenance of proper Pi homeostasis is a critical event and serum Pi level is maintained within a narrow range through an elaborate network of humoral interactions and feedback loops involving intestine, kidney, parathyroid gland and bone, and depends on the activity of a number of hormones, including parathyroid hormone, 1,25-dihydroxy vitamin D, and fibroblast growth factor 23 as major regulators of Pi homeostasis. Notably, Pi intake seemingly continues to increase as a consequence of chronic high-phosphorus (P) diets deriving from the growing consumption of highly processed foods, especially restaurant meals, fast foods, and convenience foods. Several recent reports have generated significant associations between high-P intake or high-serum Pi concentration and morbidity and mortality. Many chronic diseases, including cardiovascular diseases, obesity and even cancer have been proposed to be associated with high-P intakes and high-serum Pi concentrations. On the other hand, there is also evidence that Pi can have antiproliferative effects on some cancer cell types, depending on cell status and genetic background and achieve additive cytotoxic effects when combined with doxorubicin, illustrating its potential for clinical applications and suggesting that up-regulating Pi levels at local sites for brief times, might contribute to the development of novel and cheap modalities for therapeutic intervention in some tumours. Overall, the influence of Pi on cell function and the possible relationship to

  7. Enzyme activity in dialkyl phosphate ionic liquids.

    PubMed

    Thomas, Marie F; Li, Luen-Luen; Handley-Pendleton, Jocelyn M; van der Lelie, Daniel; Dunn, John J; Wishart, James F

    2011-12-01

    The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariella volvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v. PMID:22001053

  8. Enzyme activity in dialkyl phosphate ionic liquids

    SciTech Connect

    Thomas, M.F.; Dunn, J.; Li, L.-L.; Handley-Pendleton, J. M.; van der lelie, D.; Wishart, J. F.

    2011-12-01

    The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariellavolvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v.

  9. A novel cobalt(II)-molybdenum(V) phosphate organic-inorganic hybrid polymer

    SciTech Connect

    Shi, F.-N.; Almeida Paz, Filipe A.; Girginova, Penka I.; Nogueira, Helena I.S.; Rocha, Joao; Amaral, Vitor S.; Klinowski, Jacek; Trindade, Tito . E-mail: ttrindade@dq.ua.pt

    2006-05-15

    A new organic-inorganic hybrid cobalt(II)-molybdenum(V) phosphate polymer incorporating piperazine (pip) (H{sub 2}pip){sub 3}[Co{sub 3}Mo{sub 12}O{sub 24}(OH){sub 6}(PO{sub 4}){sub 8}(H{sub 1.5}pip){sub 4}].5(H{sub 2}O), was prepared under hydrothermal conditions. As revealed by single-crystal X-ray diffraction studies, the material is modular, built from a secondary building block composed of two anionic hexameric polyoxomolybdophosphate [Mo{sub 6}O{sub 12}(OH){sub 3}(PO{sub 4}){sub 4}]{sup 9-} moieties, bridged by a central octahedral Co{sup 2+} centre. The sandwich-type {l_brace}Co[Mo{sub 6}O{sub 12}(OH){sub 3}(PO{sub 4}){sub 4}]{sub 2}{r_brace}{sup 16-} dimers are connected via tetrahedral Co{sup 2+} metal centres, forming an infinite one-dimensional polymer. The compound constitutes the first example of a reduced sandwich-type cobalt-molybdenum phosphate in which the organic moiety (pip) is effectively coordinated to the inorganic backbone of the polymer, in this case via the tetrahedrally coordinated Co{sup 2+} centres. The magnetic behaviour of this material was investigated in the temperature range 4-298 K.

  10. Estimation of standardized phosphorus retention for inorganic phosphate sources in broilers.

    PubMed

    Liu, S B; Xie, J J; Lu, L; Li, S F; Zhang, L Y; Jiang, Y; Luo, X G

    2013-08-01

    Two experiments were conducted to estimate standardized P retention (SPR) values of dicalcium phosphate (DCP), monocalcium phosphate (MCP), and monopotassium phosphate (MKP) in broilers. In total, ninety-six 22-d-old male broilers with similar BW (780 g average) were used in each experiment. The chicks were randomly allotted to 1 of 4 treatments (P-free, DCP, MCP, or MKP diets) with 6 replicate cages of 4 chicks each in a completely randomized design. After 3-d acclimation, chicks were fasted for 24 h and then fed P-free, DCP, MCP, or MKP diets for 4 h in Exp. 1 or 72 h in Exp. 2. Excreta samples were collected for a total of 28 or 52 h (24 or 48 h after feed withdrawal) in Exp. 1 and 96 or 120 h (24 or 48 h after feed withdrawal) in Exp. 2, respectively. The excreta collection time of 52 h in Exp. 1 or 96 h in Exp. 2 was adequate for the estimation of SPR. The estimated basal endogenous P losses (EPL) in chicks fed the P-free diet were 109 ± 4 mg/52 h per bird and 49.2 ± 4.0 mg/96 h per bird in Exp. 1 and 2, respectively. The SPR values of inorganic phosphate sources corrected by the above basal EPL differed (P < 0.001) in Exp. 2 but not in Exp. 1. However, these SPR values were very similar between the 2 experiments with 68.7, 69.8, or 76.6% in Exp. 1 and 71.8, 70.6, or 78.3% in Exp. 2 for DCP, MCP, or MKP, respectively. The results from the current study indicated that, compared with the 72-h feeding and 96-h excreta collection procedure, the 4-h feeding and 52-h excreta collection procedure was a relatively quicker time- and labor-saving method for estimating the SPR values of inorganic P sources in broilers. The estimated SPR values of commonly used inorganic P sources (MCP and DCP) were about 70%. PMID:23736054

  11. Effects of inorganic phosphate on the light dependent thylakoid energization of intact spinach chloroplasts

    SciTech Connect

    Heineke, D.; Heldt, H.W. ); Stitt, M. )

    1989-09-01

    The light dependent energization of the thylakoid membrane was analyzed in isolated intact spinach (Spinacia oleracea L.) chloroplasts incubated with different concentrations of inorganic phosphate (Pi). Two independent methods were used: (a) the accumulation of ({sup 14}C)5,5-dimethyl-2,4-oxazolidinedione and ({sup 14}C)methylamine; (b) the energy dependent chlorophyll fluorescence quenching. The inhibition of CO{sub 2} fixation by superoptimal medium Pi or by adding glyceraldehyde - an inhibitor of the Calvin cycle - leads to an increased energization of the thylakoid membrane; however, the membrane energization decreases when chloroplasts are inhibited by suboptimal Pi. This specific low phosphate effect could be partially reversed by adding oxaloacetate, which regenerates the electron acceptor NADP{sup +} and stimulates linear electron transport. The energization seen in low Pi is, however, always lower than in superoptimal Pi, even in the presence of oxaloacetate. Energization recovers in the presence of low amounts of N,N{prime}-dicyclohexylcarbodiimide, which reacts with proton channels including the coupling factor 1 ATP synthase. N,N{prime}-Dicyclohexylcarbodiimide has no effect on energization of chloroplasts in superoptimal Pi. These results suggest there is a specific low phosphate proton leak in the thylakoids, and its origin is discussed.

  12. Automated determination of urinary Na+, K+, chloride, inorganic phosphate, urea, and creatinine without sample dilution, with the "RA-XT".

    PubMed

    Fesus, P D; Pressac, M; Braconnier, F; Aymard, P

    1989-03-01

    We describe how concentrations of chloride, urea, inorganic phosphate, and creatinine in urine can be measured directly, without manual sample dilution, in a discrete analyzer (the Technicon "RA-XT"). These methods were accurate for concentrations of chloride up to 280 mmol/L, urea up to 500 mmol/L, inorganic phosphate up to 50 mmol/L, and creatinine up to 30 mmol/L. CVs are less than 3% nd results correlate well with those obtained by continuous-flow analysis (SMA-II). All these reagents are stable at room temperature for three weeks. Analyses are easy to perform and infrequent calibration is required. PMID:2920416

  13. [Stable compound of inorganic pyrophosphatase with pyrophosphate obtained by a fluoride-mediated reaction with phosphate].

    PubMed

    Bakuleva, N P; Baikov, A A; Avaeva, S M

    1981-09-01

    Incubation of inorganic pyrophosphate from baker's yeast with phosphate and MgCl2 in the presence of fluoride results in a gradual inactivation of the enzyme concomitant with incorporation of PP1 (about 2 moles per mole) into the protein. The rate constant for this process shows an increase with a rise in concentrations of the three reagents, the maximal value of inactivation being 0.11 min-1. The bound PP1 is not separated by gel-filtration. The rate of spontaneous degradation of the enzyme-pyrophosphate complex and the nature of EDTA and Mg2+ effects are similar to those for the analogous compound obtained by inhibition of PP1 hydrolysis by fluoride. The data obtained suggest that during PP1 synthesis and hydrolysis by pyrophosphatase fluoride stabilizes the same intermediate of the enzyme with pyrophosphate. PMID:6117333

  14. A simple method for tuning the glass transition process in inorganic phosphate glasses.

    PubMed

    Fulchiron, René; Belyamani, Imane; Otaigbe, Joshua U; Bounor-Legaré, Véronique

    2015-01-01

    The physical modification of glass transition temperature (T(g)) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated Tgs from theoretical equations (Supplementary information) for predicting the composition dependence of T(g) for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low T(g)s have become available only recently. PMID:25666949

  15. A simple method for tuning the glass transition process in inorganic phosphate glasses

    NASA Astrophysics Data System (ADS)

    Fulchiron, René; Belyamani, Imane; Otaigbe, Joshua U.; Bounor-Legaré, Véronique

    2015-02-01

    The physical modification of glass transition temperature (Tg) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated Tgs from theoretical equations (Supplementary information) for predicting the composition dependence of Tg for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low Tgs have become available only recently.

  16. Development of a Reagentless Biosensor for Inorganic Phosphate, Applicable over a Wide Concentration Range.

    PubMed

    Solscheid, Claudia; Kunzelmann, Simone; Davis, Colin T; Hunter, Jackie L; Nofer, Annie; Webb, Martin R

    2015-08-18

    A fluorescent reagentless biosensor for inorganic phosphate (Pi), based on the E. coli PstS phosphate binding protein, was redesigned to allow measurements of higher Pi concentrations and at low, substoichiometric concentrations of biosensor. This was achieved by weakening Pi binding of the previous biosensor, and different approaches are described that could enable this change in properties. The readout, providing response to the Pi concentration, is delivered by tetramethylrhodamine fluorescence. In addition to two cysteine mutations for rhodamine labeling at positions 17 and 197, the final variant had an I76G mutation in the hinge region between the two lobes that make up the protein. Upon Pi binding, the lobes rotate on this hinge and the mutation on the hinge lowers affinity ∼200-fold, with a dissociation constant now in the tens to hundreds micromolar range, depending on solution conditions. The signal change on Pi binding was up to 9-fold, depending on pH. The suitability of the biosensor for steady-state ATPase assays was demonstrated with low biosensor usage and its advantage in ability to cope with Pi contamination. PMID:26199994

  17. Imaging Cellular Inorganic Phosphate in Caenorhabditis elegans Using a Genetically Encoded FRET-Based Biosensor

    PubMed Central

    Banerjee, Swayoma; Versaw, Wayne K.; Garcia, L. Rene

    2015-01-01

    Inorganic phosphate (Pi) has central roles in metabolism, cell signaling and energy conversion. The distribution of Pi to each cell and cellular compartment of an animal must be tightly coordinated with its dietary supply and with the varied metabolic demands of individual cells. An analytical method for monitoring Pi dynamics with spatial and temporal resolution is therefore needed to gain a comprehensive understanding of mechanisms governing the transport and recycling of this essential nutrient. Here we demonstrate the utility of a genetically encoded FRET-based Pi sensor to assess cellular Pi levels in the nematode Caenorhabditis elegans. The sensor was expressed in different cells and tissues of the animal, including head neurons, tail neurons, pharyngeal muscle, and the intestine. Cytosolic Pi concentrations were monitored using ratiometric imaging. Injection of phosphate buffer into intestinal cells confirmed that the sensor was responsive to changes in Pi concentration in vivo. Live Pi imaging revealed cell-specific and developmental stage-specific differences in cytosolic Pi concentrations. In addition, cellular Pi levels were perturbed by food deprivation and by exposure to the respiratory inhibitor cyanide. These results suggest that Pi concentration is a sensitive indicator of metabolic status. Moreover, we propose that live Pi imaging in C. elegans is a powerful approach to discern mechanisms that govern Pi distribution in individual cells and throughout an animal. PMID:26484766

  18. Characterization of two genetically separable inorganic phosphate transport systems in Escherichia coli.

    PubMed Central

    Willsky, G R; Malamy, M H

    1980-01-01

    Inorganic phosphate (Pi) transport by wild-type cells of Escherichia coli grown in excess phosphate-containing media involves two genetically separable transport systems. Cells dependent upon the high affinity-low velocity Pst (phosphate specific transport) system have a Km of 0.43 +/- 0.2 microM Pi and a Vmax of 15.9 +/- 0.3 nmol of Pi (mg [dry weight]-1min-1) and will grow in the presence of arsenate in the medium. However, cells dependent upon the low affinity-high velocity Pit (Pi transport) system have a Km of 38.2 +/- 0.4 microM and a Vmax of 55 +/- 1.9 nmol of Pi (mg [dry weight]-1min-1), and these cells cannot grow in the presence of an arsenate-to-Pi ratio of 10 in the medium. Pi transport by both systems was sensitive to the energy uncoupler 2,4-dinitrophenol and the sulfhydryl reagent N-ethylmaleimide, whereas only the Pst system was very sensitive to sodium cyanide. Evidence is presented that Pi is transported as Pi or a very labile intermediate and that accumulated Pi does not exit through the Pst or Pit systems from glucose-grown cells. Kinetic analysis of Pi transport in the wild-type strain containing both the Pst and Pit transport systems revealed that each system was not operating at full capacity. In addition, Pi transport in the wild-type strain was completely sensitive to sodium cyanide (a characteristic of the Pst system). PMID:6998957

  19. Artificial cytoskeletal structures within enzymatically active bio-inorganic protocells.

    PubMed

    Kumar, Ravinash Krishna; Li, Mei; Olof, Sam N; Patil, Avinash J; Mann, Stephen

    2013-02-11

    The fabrication of enzymatically active, semi-permeable bio-inorganic protocells capable of self-assembling a cytoskeletal-like interior and undergoing small-molecule dephosphorylation reactions is described. Reversible disassembly of an amino acid-derived supramolecular hydrogel within the internalized reaction space is used to tune the enzymatic activity of the nanoparticle-bounded inorganic compartments. PMID:23027575

  20. Effect of decreasing dietary phosphorus supply on net recycling of inorganic phosphate in lactating dairy cows.

    PubMed

    Puggaard, L; Kristensen, N B; Sehested, J

    2011-03-01

    Five ruminally cannulated lactating Holstein cows, fitted with permanent indwelling catheters in the mesenteric vein, hepatic vein, portal vein, and an artery were used to study intestinal absorption and net recycling of inorganic phosphate (P(i)) to the gastrointestinal tract. Treatments were low P (LP; 2.4 g of P/kg of DM) and high P (HP; 3.4 g of P/kg of DM). The dietary total P (tP) concentrations were obtained by replacing 0.50% calcium carbonate in the LP diet with 0.50% monocalcium phosphate in the HP diet. Diets were fed for 14 d and cows were sampled on d 14 in each period. Cows were fed restrictively, resulting in equal dry matter intakes as well as milk, fat, and protein yields between treatments. Net P(i) recycling (primarily salivary) was estimated as the difference between net portal plasma flux (net absorption of P(i)) and apparently digested tP (feed - fecal tP difference). Phosphorus intake, apparently digested tP, and fecal tP excretion decreased with LP. An effect of decreased tP intake on net portal plasma flux of P(i) could not be detected. However, despite numerically minute net fluxes across the liver, the net splanchnic flux of P(i) was less in LP compared with that in HP. Though arterial plasma P(i) concentration decreased, net P(i) recycling was not decreased when tP intake was decreased, and recycling of P(i) was maintained at the expense of deposition of P(i) in bones. Data are not consistent with salivary P(i) secretion being the primary regulator of P(i) homeostasis at low tP intakes. On the contrary, maintaining salivary P(i) recycling at low tP intakes indicates that rumen function was prioritized at the expense of bone P reserves. PMID:21338807

  1. High Inorganic Phosphate Intake Promotes Tumorigenesis at Early Stages in a Mouse Model of Lung Cancer

    PubMed Central

    Lee, Somin; Kim, Ji-Eun; Hong, Seong-Ho; Lee, Ah-Young; Park, Eun-Jung; Seo, Hwi Won; Chae, Chanhee; Doble, Philip; Bishop, David; Cho, Myung-Haing

    2015-01-01

    Inorganic phosphate (Pi) is required by all living organisms for the development of organs such as bone, muscle, brain, and lungs, regulating the expression of several critical genes as well as signal transduction. However, little is known about the effects of prolonged dietary Pi consumption on lung cancer progression. This study investigated the effects of a high-phosphate diet (HPD) in a mouse model of adenocarcinoma. K-rasLA1 mice were fed a normal diet (0.3% Pi) or an HPD (1% Pi) for 1, 2, or 4 months. Mice were then sacrificed and subjected to inductively coupled plasma mass/optical emission spectrometry and laser ablation inductively coupled plasma mass-spectrometry analyses, western blot analysis, histopathological, immunohistochemical, and immunocytochemical analyses to evaluate tumor formation and progression (including cell proliferation, angiogenesis, and apoptosis), changes in ion levels and metabolism, autophagy, epithelial-to-mesenchymal transition, and protein translation in the lungs. An HPD accelerated tumorigenesis, as evidenced by increased adenoma and adenocarcinoma rates as well as tumor size. However, after 4 months of the HPD, cell proliferation was arrested, and marked increases in liver and lung ion levels and in energy production via the tricarboxylic acid cycle in the liver were observed, which were accompanied by increased autophagy and decreased angiogenesis and apoptosis. These results indicate that an HPD initially promotes but later inhibits lung cancer progression because of metabolic adaptation leading to tumor cell quiescence. Moreover, the results suggest that carefully regulated Pi consumption are effective in lung cancer prevention. PMID:26285136

  2. High Inorganic Phosphate Intake Promotes Tumorigenesis at Early Stages in a Mouse Model of Lung Cancer.

    PubMed

    Lee, Somin; Kim, Ji-Eun; Hong, Seong-Ho; Lee, Ah-Young; Park, Eun-Jung; Seo, Hwi Won; Chae, Chanhee; Doble, Philip; Bishop, David; Cho, Myung-Haing

    2015-01-01

    Inorganic phosphate (Pi) is required by all living organisms for the development of organs such as bone, muscle, brain, and lungs, regulating the expression of several critical genes as well as signal transduction. However, little is known about the effects of prolonged dietary Pi consumption on lung cancer progression. This study investigated the effects of a high-phosphate diet (HPD) in a mouse model of adenocarcinoma. K-rasLA1 mice were fed a normal diet (0.3% Pi) or an HPD (1% Pi) for 1, 2, or 4 months. Mice were then sacrificed and subjected to inductively coupled plasma mass/optical emission spectrometry and laser ablation inductively coupled plasma mass-spectrometry analyses, western blot analysis, histopathological, immunohistochemical, and immunocytochemical analyses to evaluate tumor formation and progression (including cell proliferation, angiogenesis, and apoptosis), changes in ion levels and metabolism, autophagy, epithelial-to-mesenchymal transition, and protein translation in the lungs. An HPD accelerated tumorigenesis, as evidenced by increased adenoma and adenocarcinoma rates as well as tumor size. However, after 4 months of the HPD, cell proliferation was arrested, and marked increases in liver and lung ion levels and in energy production via the tricarboxylic acid cycle in the liver were observed, which were accompanied by increased autophagy and decreased angiogenesis and apoptosis. These results indicate that an HPD initially promotes but later inhibits lung cancer progression because of metabolic adaptation leading to tumor cell quiescence. Moreover, the results suggest that carefully regulated Pi consumption are effective in lung cancer prevention. PMID:26285136

  3. Cytoplasmic Acidification Induced by Inorganic Phosphate Uptake in Suspension Cultured Catharanthus roseus Cells

    PubMed Central

    Sakano, Katsuhiro; Yazaki, Yoshiaki; Mimura, Tetsuro

    1992-01-01

    Cytoplasmic acidification during inorganic phosphate (Pi) absorption by Catharanthus roseus cells were studied by means of a fluorescent pH indicator, 2′,7′-bis-(2-carboxyethyl)-5 carboxyfluorescein (acetomethylester) (BCECF), and 31P-nuclear magnetic resonance spectroscopy. Cytoplasmic acidification measured by decrease in the fluorescence intensity started immediately after Pi application. Within a minute or so, a stable state was attained and no further acidification occurred, whereas Pi absorption was still proceeding. As soon as Pi in the medium was exhausted, cytoplasmic pH started to recover. Coincidentally, the medium pH started to recover toward the original acidic pH. The Pi-induced changes in the cytoplasmic pH were confirmed by 31P-nuclear magnetic resonance study. Maximum acidification of the cytoplasm induced by 1.7 millimolar Pi was 0.2 pH units. Vacuolar pH was also affected by Pi. In some experiments, but not all, pH decreased reversibly by 0.2 to 0.3 pH units during Pi absorption. Results suggest that the cytoplasmic pH is regulated by proton pumps in the plasma membrane and in the tonoplast. In addition, other mechanisms that could consume extra protons in the cytoplasm are suggested. ImagesFigure 1 PMID:16668939

  4. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa.

    PubMed

    Rico-Jiménez, Miriam; Reyes-Darias, Jose Antonio; Ortega, Álvaro; Díez Peña, Ana Isabel; Morel, Bertrand; Krell, Tino

    2016-01-01

    Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis-a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread. PMID:27353565

  5. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa

    PubMed Central

    Rico-Jiménez, Miriam; Reyes-Darias, Jose Antonio; Ortega, Álvaro; Díez Peña, Ana Isabel; Morel, Bertrand; Krell, Tino

    2016-01-01

    Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis—a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread. PMID:27353565

  6. Plasma Calcium, Inorganic Phosphate and Magnesium During Hypocalcaemia Induced by a Standardized EDTA Infusion in Cows

    PubMed Central

    Mellau, LSB; Jørgensen, RJ; Enemark, JMD

    2001-01-01

    The intravenous Na2EDTA infusion technique allows effective specific chelation of circulating Ca2+ leading to a progressive hypocalcaemia. Methods previously used were not described in detail and results obtained by monitoring total and free ionic calcium were not comparable due to differences in sampling and analysis. This paper describes a standardized EDTA infusion technique that allowed comparison of the response of calcium, phosphorus and magnesium between 2 groups of experimental cows. The concentration of the Na2EDTA solution was 0.134 mol/l and the flow rate was standardized at 1.2 ml/kg per hour. Involuntary recumbency occurred when ionised calcium dropped to 0.39 – 0.52 mmol/l due to chelation. An initial fast drop of ionized calcium was observed during the first 20 min of infusion followed by a fluctuation leading to a further drop until recumbency. Pre-infusion [Ca2+] between tests does not correlate with the amount of EDTA required to induce involuntary recumbence. Total calcium concentration measured by atomic absorption remained almost constant during the first 100 min of infusion but declined gradually when the infusion was prolonged. The concentration of inorganic phosphate declined gradually in a fluctuating manner until recumbency. Magnesium concentration remained constant during infusion. Such electrolyte responses during infusion were comparable to those in spontaneous milk fever. The standardized infusion technique might be useful in future experimental studies. PMID:11503370

  7. Sodium-dependent uptake of inorganic phosphate by the intracellular malaria parasite

    NASA Astrophysics Data System (ADS)

    Saliba, Kevin J.; Martin, Rowena E.; Bröer, Angelika; Henry, Roselani I.; Siobhan McCarthy, C.; Downie, Megan J.; Allen, Richard J. W.; Mullin, Kylie A.; McFadden, Geoffrey I.; Bröer, Stefan; Kirk, Kiaran

    2006-10-01

    As the malaria parasite, Plasmodium falciparum, grows within its host erythrocyte it induces an increase in the permeability of the erythrocyte membrane to a range of low-molecular-mass solutes, including Na+ and K+ (ref. 1). This results in a progressive increase in the concentration of Na+ in the erythrocyte cytosol. The parasite cytosol has a relatively low Na+ concentration and there is therefore a large inward Na+ gradient across the parasite plasma membrane. Here we show that the parasite exploits the Na+ electrochemical gradient to energize the uptake of inorganic phosphate (Pi), an essential nutrient. Pi was taken up into the intracellular parasite by a Na+-dependent transporter, with a stoichiometry of 2Na+:1Pi and with an apparent preference for the monovalent over the divalent form of Pi. A Pi transporter (PfPiT) belonging to the PiT family was cloned from the parasite and localized to the parasite surface. Expression of PfPiT in Xenopus oocytes resulted in Na+-dependent Pi uptake with characteristics similar to those observed for Pi uptake in the parasite. This study provides new insight into the significance of the malaria-parasite-induced alteration of the ionic composition of its host cell.

  8. The efficiency of contraction in rabbit skeletal muscle fibres, determined from the rate of release of inorganic phosphate

    PubMed Central

    He, Zhen-He; Chillingworth, Rodney K; Brune, Martin; Corrie, John E T; Webb, Martin R; Ferenczi, Michael A

    1999-01-01

    The relationship between mechanical power output and the rate of ATP hydrolysis was investigated in segments of permeabilized fibres isolated from rabbit psoas muscle. Contractions were elicited at 12 °C by photolytic release of ATP from the P3-1-(2-nitrophenyl)ethyl ester of ATP (NPE-caged ATP). Inorganic phosphate (Pi) release was measured by a fluorescence method using a coumarin-labelled phosphate binding protein. Force and sarcomere length were also monitored. ATPase activity was determined from the rate of appearance of Pi during each phase of contraction. The ATPase rate was 10.3 s−1 immediately following release of ATP and 5.1 s−1 during the isometric phase prior to the applied shortening. It rose hyperbolically with shortening velocity, reaching 18.5 s−1 at a maximal shortening velocity > 1 ML s−1 (muscle lengths s−1). Sarcomeres shortened at 0.09 ML s−1 immediately following the photolytic release of ATP and at 0.04 ML s−1 prior to the period of applied shortening. The high initial ATPase rate may be largely attributed to initial sarcomere shortening. During shortening, maximal power output was 28 W l−1. Assuming the free energy of hydrolysis is 50 kJ mol−1, the efficiency of contraction was calculated from the power output at each shortening velocity. The maximum efficiency was 0.36 at a shortening velocity of 0.27 ML s−1, corresponding to a force level 51 % of that in the isometric state. At the maximal shortening velocity, only 10 % of the myosin heads are attached to the thin filaments at any one time. PMID:10358123

  9. Inorganic polymeric phosphate/polyphosphate as an inducer of alkaline phosphatase and a modulator of intracellular Ca2+ level in osteoblasts (SaOS-2 cells) in vitro.

    PubMed

    Müller, Werner E G; Wang, Xiaohong; Diehl-Seifert, Bärbel; Kropf, Klaus; Schlossmacher, Ute; Lieberwirth, Ingo; Glasser, Gunnar; Wiens, Matthias; Schröder, Heinz C

    2011-06-01

    Inorganic polymeric phosphate is a physiological polymer that accumulates in bone cells. In the present study osteoblast-like SaOS-2 cells were exposed to this polymer, complexed in a 2:1 stoichiometric ratio with Ca(2+), polyP (Ca(2+) salt). At a concentration of 100 μM, polyP (Ca(2+) salt) caused a strong increase in the activity of the alkaline phosphatase and also an induction of the steady-state expression of the gene encoding this enzyme. Comparative experiments showed that polyP (Ca(2+) salt) can efficiently replace β-glycerophosphate in the in vitro hydroxyapatite (HA) biomineralization assay. In the presence of polyP (Ca(2+) salt) the cells extensively form HA crystallites, which remain intimately associated with or covered by the plasma membrane. Only the tips of the crystallites are directly exposed to the extracellular space. Element mapping by scanning electron microscopy/energy-dispersive X-ray spectroscopy coupled to a silicon drift detector supported the finding that organic material was dispersed within the crystallites. Finally, polyP (Ca(2+) salt) was found to cause an increase in the intracellular Ca(2+) level, while polyP, as well as inorganic phosphate (P(i)) or Ca(2+) alone, had no effect at the concentrations used. These findings are compatible with the assumption that polyP (Ca(2+) salt) is locally, on the surface of the SaOS-2 cells, hydrolyzed to P(i) and Ca(2+). We conclude that the inorganic polymer polyP (Ca(2+) salt) in concert with a second inorganic, and physiologically occurring, polymer, biosilica, activates osteoblasts and impairs the maturation of osteoclasts. PMID:21397057

  10. Genetic analysis of mutants affected in the Pst inorganic phosphate transport system.

    PubMed Central

    Cox, G B; Rosenberg, H; Downie, J A; Silver, S

    1981-01-01

    A number of mutant alleles affecting the Pst phosphate transport system have been divided into three complementation groups on the basis of constitutive alkaline phosphatase activity in appropriate partial diploid strains. The three complementation groups were represented by the alleles pstA2 and phoT32 and the newly described allele pstB401. The two alleles phoS28 and phoS21 appeared to be polar. The phoS28 allele affected both the phoT and pstB genes but not the pstA gene, whereas the phoS21 allele appeared to be a mutation in the pstA gene exerting polar effects on both the pstB and phoT genes. It was concluded that the three genes pstA, pstB, and phoT were part of an operon and that the phosphate-binding protein was not coded for by any of these genes. The phoS gene, defined as the structural gene for the phosphate-binding protein, is also part of the operon, but the phoS28 and phoS21 alleles are not mutations in the phoS gene and were reclassified as pho-28 and pho-21 alleles. The gene order was concluded to be pstA-(pstB-phoT)-phoS, with the pstA gene promotor proximal and the direction of transcription opposite to that of the nearby unc operon. Images PMID:7026529

  11. Active site - a site of binding of affinity inhibitors in baker's yeast inorganic pyrophosphatase

    SciTech Connect

    Svyato, I.E.; Sklyankina, V.A.; Avaeva, S.M.

    1986-03-20

    The interaction of the enzyme-substrate complex with methyl phosphate, O-phosphoethanolamine, O-phosphopropanolamine, N-acetylphosphoserine, and phosphoglyolic acid, as well as pyrophosphatase, modified by monoesters of phosphoric acid, with pyrophosphate and tripolyphosphate, was investigated. It was shown that the enzyme containing the substrate in the active site does not react with monophosphates, but modified pyrophosphatase entirely retains the ability to bind polyanions to the regulatory site. It is concluded that the inactivation of baker's yeast inorganic pyrophosphatase by monoesters of phosphoric acid, which are affinity inhibitors of it, is the result of modification of the active site of the enzyme.

  12. Inorganic Phosphate and Sodium Ions Are Cogerminants for Spores of Clostridium perfringens Type A Food Poisoning-Related Isolates▿

    PubMed Central

    Paredes-Sabja, Daniel; Udompijitkul, Pathima; Sarker, Mahfuzur R.

    2009-01-01

    Clostridium perfringens type A isolates carrying a chromosomal copy of the enterotoxin (cpe) gene are involved in the majority of food poisoning (FP) outbreaks, while type A isolates carrying a plasmid-borne cpe gene are involved in C. perfringens-associated non-food-borne (NFB) gastrointestinal diseases. To cause diseases, C. perfringens spores must germinate and return to active growth. Previously, we showed that only spores of FP isolates were able to germinate with K+ ions. We now found that the spores of the majority of FP isolates, but none of the NFB isolates, germinated with the cogerminants Na+ and inorganic phosphate (NaPi) at a pH of ∼6.0. Spores of gerKA-KC and gerAA mutants germinated to a lesser extent and released less dipicolinic acid (DPA) than did wild-type spores with NaPi. Although gerKB spores germinated to a similar extent as wild-type spores with NaPi, their rate of germination was lower. Similarly, gerO and gerO gerQ mutant spores germinated slower and released less DPA than did wild-type spores with NaPi. In contrast, gerQ spores germinated to a slightly lesser extent than wild-type spores but released all of their DPA during NaPi germination. In sum, this study identified NaPi as a novel nutrient germinant for spores of most FP isolates and provided evidence that proteins encoded by the gerKA-KC operon, gerAA, and gerO are required for NaPi-induced spore germination. PMID:19666724

  13. 2,3-diphosphoglycerate phosphatase activity of phosphoglycerate mutase: stimulation by vanadate and phosphate

    SciTech Connect

    Stankiewicz, P.J.; Gresser, M.J.; Tracey, A.S.; Hass, L.F.

    1987-03-10

    The binding of inorganic vanadate (V/sub i/) to rabbit muscle phosphoglycerate mutase (PGM), studied by using /sup 51/V nuclear magnetic resonance spectroscopy, shows a sigmoidal dependence on vanadate concentration with a stoichiometry of four vanadium atoms per PGM molecule at saturating (V/sub i/). The data are consistent with binding of one divanadate ion to each of the two subunits of PGM in a noncooperative manner with an intrinsic dissociation constant of 4 x 10/sup -6/ M. The relevance of this result to other studies which have shown that the V/sub i/-stimulated 2,3-diphosphoglycerate (2,3-DPG) phosphatase activity of PGM has a sigmoidal dependence on (V/sub i/) with a Hill coefficient of 2.0 is discussed. At pH 7.0, inorganic phosphate has little effect on the 2,3-DPG phosphatase activity of PGM, even at concentrations as high as 50 mM. Similarly, 25 ..mu..M V/sub i/ has little effect on the phosphatase activity. However, in the presence of 25 ..mu..M V/sub i/, a phosphate concentration of 20 mM increases the phosphatase activity by more than 3-fold. This behavior is rationalized in terms of activation of the phosphatase activity by a phosphate/vanadate mixed anhydride. This interpretation is supported by the observation of strong activation of the phosphatase activity by inorganic pyrophosphate. A molecular mechanism for the observed effects of vanadate is proposed, and the relevance of this study to the possible use of vanadate as a therapeutic agent for the treatment of sickle cell anemia is discussed.

  14. Effect of inorganic phosphate concentration on the nature of inner mitochondrial membrane alterations mediated by Ca2+ ions. A proposed model for phosphate-stimulated lipid peroxidation.

    PubMed

    Kowaltowski, A J; Castilho, R F; Grijalba, M T; Bechara, E J; Vercesi, A E

    1996-02-01

    Addition of high concentrations (>1 mm) of inorganic phosphate (Pi) or arsenate to Ca2+-loaded mitochondria was followed by increased rates of H2O2 production, membrane lipid peroxidation, and swelling. Mitochondrial swelling was only partially prevented either by butylhydroxytoluene, an inhibitor of lipid peroxidation, or cyclosporin A, an inhibitor of the mitochondrial permeability transition pore. This swelling was totally prevented by the simultaneous presence of these compounds. At lower Pi concentrations (1 mm), mitochondrial swelling is reversible and prevented by cyclosporin A, but not by butylhydroxytoluene. In any case (low or high phosphate concentration) exogenous catalase prevented mitochondrial swelling, suggesting that reactive oxygen species (ROS) participate in these mechanisms. Altogether, the data suggest that, at low Pi concentrations, membrane permeabilization is reversible and mediated by opening of the mitochondrial permeability transition pore, whereas at high Pi concentrations, membrane permeabilization is irreversible because lipid peroxidation also takes place. Under these conditions, lipid peroxidation is strongly inhibited by sorbate, a putative quencher of triplet carbonyl species. This suggests that high Pi or arsenate concentrations stimulate propagation of the peroxidative reactions initiated by mitochondrial-generated ROS because these anions are able to catalyze Cn-aldehyde tautomerization producing enols, which can be oxidized by hemeproteins to yield the lower Cn - 1-aldehyde in the triplet state. This proposition was also supported by experiments using a model system consisting of phosphatidylcholine/dicethylphosphate liposomes and the triplet acetone-generating system isobutanal/horseradish peroxidase, where phosphate and Ca2+ cooperate to increase the yield of thiobarbituric acid-reactive substances. PMID:8621682

  15. The effect of inorganic phosphate on force generation in single myofibrils from rabbit skeletal muscle.

    PubMed

    Tesi, C; Colomo, F; Nencini, S; Piroddi, N; Poggesi, C

    2000-06-01

    In striated muscle, force generation and phosphate (P(i)) release are closely related. Alterations in the [P(i)] bathing skinned fibers have been used to probe key transitions of the mechanochemical coupling. Accuracy in this kind of studies is reduced, however, by diffusional barriers. A new perfusion technique is used to study the effect of [P(i)] in single or very thin bundles (1-3 microM in diameter; 5 degrees C) of rabbit psoas myofibrils. With this technique, it is possible to rapidly jump [P(i)] during contraction and observe the transient and steady-state effects on force of both an increase and a decrease in [P(i)]. Steady-state isometric force decreases linearly with an increase in log[P(i)] in the range 500 microM to 10 mM (slope -0.4/decade). Between 5 and 200 microM P(i), the slope of the relation is smaller ( approximately -0.07/decade). The rate constant of force development (k(TR)) increases with an increase in [P(i)] over the same concentration range. After rapid jumps in [P(i)], the kinetics of both the force decrease with an increase in [P(i)] (k(Pi(+))) and the force increase with a decrease in [P(i)] (k(Pi(-))) were measured. As observed in skinned fibers with caged P(i), k(Pi(+)) is about three to four times higher than k(TR), strongly dependent on final [P(i)], and scarcely modulated by the activation level. Unexpectedly, the kinetics of force increase after jumps from high to low [P(i)] is slower: k(Pi(-)) is indistinguishable from k(TR) measured at the same [P(i)] and has the same calcium sensitivity. PMID:10827985

  16. Characterization of the mineral phosphate-solubilizing activity of Pantoea agglomerans MMB051 isolated from an iron-rich soil in southeastern Venezuela (Bolívar State).

    PubMed

    Sulbarán, Miguel; Pérez, Elizabeth; Ball, María M; Bahsas, Alí; Yarzábal, Luis Andrés

    2009-04-01

    The mineral phosphate-solubilizing (MPS) activity of a Pantoea agglomerans strain, namely MMB051, isolated from an iron-rich, acidic soil near Ciudad Piar (Bolívar State, Venezuela), was characterized on a chemically defined medium (NBRIP). Various insoluble inorganic phosphates, including tri-calcium phosphate [Ca(3)(PO(4))(2)], iron phosphate (FePO(4)), aluminum phosphate (AlPO(4)), and Rock Phosphate (RP) were tested as sole sources of P for bacterial growth. Solubilization of Ca(3)(PO(4))(2) was very efficient and depended on acidification of the external milieu when MMB051 cells were grown in the presence of glucose. This was also the case when RP was used as the sole P source. On the other hand, the solubilization efficiency toward more insoluble mineral phosphates (FePO(4) and AlPO(4)) was shown to be very low. Even though gluconic acid (GA) was detected on culture supernatants of strain MMB051, a consequence of the direct oxidation pathway of glucose, inorganic-P solubilization seemed also to be related to other processes dependent on active cell growth. Among these, proton release by ammonium (NH(4)(+) ) fixation appeared to be of paramount importance to explain inorganic-P solubilization mediated by strain MMB051. On the contrary, the presence of nitrate (NO(3)(-) ) salts as the sole N source affected negatively the ability of MMB051 cells to solubilize inorganic P. PMID:19067045

  17. Structure of human farnesyl pyrophosphate synthase in complex with an aminopyridine bisphosphonate and two molecules of inorganic phosphate

    SciTech Connect

    Park, Jaeok; Lin, Yih-Shyan; Tsantrizos, Youla S.; Berghuis, Albert M.

    2014-02-19

    A co-crystal structure of human farnesyl pyrophosphate synthase in complex with an aminopyridine bisphosphonate, YS0470, and two molecules of inorganic phosphate has been determined. The identity of the phosphate ligands was confirmed by anomalous diffraction data. Human farnesyl pyrophosphate synthase (hFPPS) produces farnesyl pyrophos@@phate, an isoprenoid essential for a variety of cellular processes. The enzyme has been well established as the molecular target of the nitrogen-containing bisphosphonates (N-BPs), which are best known for their antiresorptive effects in bone but are also known for their anticancer properties. Crystal structures of hFPPS in ternary complexes with a novel bisphosphonate, YS0470, and the secondary ligands inorganic phosphate (P{sub i}), inorganic pyrophosphate (PP{sub i}) and isopentenyl pyrophosphate (IPP) have recently been reported. Only the co-binding of the bisphosphonate with either PP{sub i} or IPP resulted in the full closure of the C-@@terminal tail of the enzyme, a conformational change that is required for catalysis and that is also responsible for the potent in vivo efficacy of N-BPs. In the present communication, a co-crystal structure of hFPPS in complex with YS0470 and two molecules of P{sub i} is reported. The unusually close proximity between these ligands, which was confirmed by anomalous diffraction data, suggests that they interact with one another, with their anionic charges neutralized in their bound state. The structure also showed the tail of the enzyme to be fully disordered, indicating that simultaneous binding of two P{sub i} molecules with a bisphosphonate cannot induce the tail-closing conformational change in hFPPS. Examination of homologous FPPSs suggested that this ligand-dependent tail closure is only conserved in the mammalian proteins. The prevalence of P{sub i}-bound hFPPS structures in the PDB raises a question regarding the in vivo relevance of P{sub i} binding to the function of the enzyme.

  18. Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests.

    PubMed

    Zhu, Feifei; Lu, Xiankai; Liu, Lei; Mo, Jiangming

    2015-01-01

    Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al(3+) replacement of Ca(2+) in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests. PMID:25605567

  19. Methotrexate loaded self stabilized calcium phosphate nanoparticles: a novel inorganic carrier for intracellular drug delivery.

    PubMed

    Mukesh, Ukawala; Kulkarni, Vijay; Tushar, Rajyaguru; Murthy, R S R

    2009-02-01

    Calcium phosphate is considered as a potential biomaterial for drug and gene delivery because of its excellent features. In this study, we reported the formulation and characterization of calcium phosphate nanoparticle containing anticancer drug, methotrexate (MTX). Calcium phosphate nanoparticles containing MTX (CaPi-MTX) were prepared by reverse micelles technique. CaPi-MTX nanoparticles of average size 262 +/- 47.64 nm with entrapment efficiency of 58.04 +/- 4.09% were obtained. The IR spectrum of CaPi-MTX showed characteristics of composite formation of hydroxyapatite with MTX. X-RD analysis revealed that, CaPi-MTX nanoparticles were crystalline and in hydroxyapatite form. TEM studies showed that CaPi-MTX nanoparticles were spherical in shape. In vitro release study of CaPi-MTX nanoparticles showed slow release of MTX at physiological pH (pH 7.4) while > 90% release was observed within 3-4 hours at endosomal pH (pH 5.5 and pH 6.0). Confocal microscopy was performed using CHO cell lines, showed intracellular localization of FITC-Dextran loaded calcium phosphate nanoparticles. Results indicate that prepared CaPi-MTX nanoparticles could serve the purpose for intracellular drug delivery. PMID:20055112

  20. EF-G Activation by Phosphate Analogs.

    PubMed

    Salsi, Enea; Farah, Elie; Ermolenko, Dmitri N

    2016-05-22

    Elongation factor G (EF-G) is a universally conserved translational GTPase that promotes the translocation of tRNA and mRNA through the ribosome. EF-G binds to the ribosome in a GTP-bound form and subsequently catalyzes GTP hydrolysis. The contribution of the ribosome-stimulated GTP hydrolysis by EF-G to tRNA/mRNA translocation remains debated. Here, we show that while EF-G•GDP does not stably bind to the ribosome and induce translocation, EF-G•GDP in complex with phosphate group analogs BeF3(-) and AlF4(-) promotes the translocation of tRNA and mRNA. Furthermore, the rates of mRNA translocation induced by EF-G in the presence of GTP and a non-hydrolyzable analog of GTP, GDP•BeF3(-) are similar. Our results are consistent with the model suggesting that GTP hydrolysis is not directly coupled to mRNA/tRNA translocation. Hence, GTP binding is required to induce the activated, translocation-competent conformation of EF-G while GTP hydrolysis triggers EF-G release from the ribosome. PMID:27063503

  1. Increase in ATP consumption during shortening in skinned fibres from rabbit psoas muscle: effects of inorganic phosphate.

    PubMed Central

    Potma, E J; Stienen, G J

    1996-01-01

    1. The influence of inorganic phosphate (P(i)) on the relationship between ATP consumption and mechanical performance under isometric and dynamic conditions was investigated in chemically skinned single fibres or thin bundles from rabbit psoas muscle. Myofibrillar ATPase activity was measured photometrically by enzymatic coupling of the regeneration of ATP to the oxidation of NADH. NADH absorbance at 340 nm was determined inside a miniature (4 microliters) measuring chamber. 2. ATP consumption due to isovelocity shortenings was measured in the range between 0.0625 and 1 L0 s-1(L0: fibre length previous to shortening, corresponding to a sarcomere length of 2.64 microns), in solutions without added P(i) and with 30 mM P(i). To get an estimate of the amount of ATP utilized during the shortening phase, quick releases of various amplitudes were also performed. 3. After quick releases, sufficiently large that force dropped to zero, extra ATP was hydrolysed which was largely independent of the amplitude of the release and of the period of unloaded shortening. This extra amount, above the isometric ATP turnover, corresponded to about 0.7 and 0.5 ATP molecules per myosin head at 0 and 30 mM P(i), respectively. 4. ATP turnover during the isovelocity shortenings was higher than isometric turnover and increased with increasing shortening velocity up to about 2.7 times the isometric value. At low and moderate velocities of shortening (< 0.5 L0 s-1), P(i) reduced ATP turnover during isovelocity shortening and isometric ATP turnover to a similar extent, i.e. a decrease to about 77% between 0 and 30 mM added P(i). 5. The extra ATP turnover above the isometric value, resulting from isovelocity shortenings studied at different speeds, was proportional to the power output of the preparation, both in the absence and presence of added [P(i)]. 6. The effect of shortening velocity and [P(i)] on energy turnover can be understood in a cross-bridge model that consists of a detached, a non

  2. Nitrate and phosphate leaching in a Phaeozem soil treated with biosolids, composted biosolids and inorganic fertilizers.

    PubMed

    Esteller, M V; Martínez-Valdés, H; Garrido, S; Uribe, Q

    2009-06-01

    The use of organic wastes in agriculture may increase the production of crops by incorporating organic matter and nutrients into the soil, and by improving its physical characteristics; however, this use may cause environmental problems such as the leaching of certain ions. The objective of this study was to establish possible nitrogen and phosphorus leaching under real field conditions in Phaeozem soils. The experimental work was performed in a corn (Zea mays L.) field where three plots were conditioned with inorganic fertilizer, three plots with 4.5 Mgha(-1) of biosolids on dry basis, and three plots with the same amount of composted biosolids. The quality of biosolids and composted biosolids complied with the Mexican Official Standards. Soil water samples were collected with suction cups during two agricultural cycles and were analysed. Soil samples were also taken and analysed. The N-NO(3) concentrations in soil water fluctuated between 0.9 and 98mgL(-1) in the composted biosolid treatment, between 0.7 and 64 mgL(-1) in the biosolid treatment, and between 1 and 61 mgL(-1) in the inorganic fertilizer treatment. The maximum concentration of N-NO(2) and N-NH(3) in soil water was 1.02 and 2.65 mgL(-1), respectively. The greatest percentage of nitrogen leached is produced when inorganic fertilizer is used (37.4% and 24.0% N leached in the first and second years, respectively), followed by composted biosolids (17.1% and 13.5% N leached in the first and second years, respectively) and last by biosolids (11% for both years). This difference could be related to the form in which nitrogen is present in the fertilizers, while commercial fertilizer is as inorganic nitrogen, organic wastes are basically presented as organic nitrogen. The maximum PO(4)(3-) concentration in soil water was 1.9 mgL(-1) in the composted biosolid treatment, 1.7mgL(-1) in the biosolid treatment and 0.9 mgL(-1) in the inorganic fertilizer treatment. The estimated percentage of leached phosphorus

  3. Growth of optically active chiral inorganic films through DNA self-assembly and silica mineralisation.

    PubMed

    Liu, Ben; Han, Lu; Duan, Yingying; Cao, Yunayuan; Feng, Ji; Yao, Yuan; Che, Shunai

    2014-01-01

    The circularly polarized reflection of nature is due to their distinct azimuthally twisted or helical character in the nanostructure of the surface films. Although many chiral inorganic powders have been successfully synthesised, the artificial synthesis of chiral inorganic films is rare. Herein, we reported a facile synthetic route for the growth of monolayered chiral film on the quaternary ammonium-modified silicon substrate. The films grew on the substrate surface because of the strong electrostatic interaction between positively charged quaternary ammonium groups and negatively charged phosphate groups of DNA, with subsequent growth to right-handed, vertically aligned, impeller-like helical architectures with left-handed two-dimensional square p4mm-structured DNA chiral packing. The DNA-silica composite films exhibited strong optical activity at 295 nm and in the range of 400-800 nm, corresponding to DNA chiral packing (absorption) and to the helical blade in the impeller (scattering), respectively. Upon removal of DNA templates, the pure inorganic impeller-like helical morphology was maintained; consequently, the scattering-based optical response was blue-shifted approximately 200 nm as a result of a decrease in the effective average refractive index. The hierarchical structures were reflected from the surfaces by cross-polarised light, which confirmed that the films were strongly birefringent, with long-range anisotropy. PMID:24784912

  4. Growth of Optically Active Chiral Inorganic Films through DNA Self-Assembly and Silica Mineralisation

    NASA Astrophysics Data System (ADS)

    Liu, Ben; Han, Lu; Duan, Yingying; Cao, Yunayuan; Feng, Ji; Yao, Yuan; Che, Shunai

    2014-05-01

    The circularly polarized reflection of nature is due to their distinct azimuthally twisted or helical character in the nanostructure of the surface films. Although many chiral inorganic powders have been successfully synthesised, the artificial synthesis of chiral inorganic films is rare. Herein, we reported a facile synthetic route for the growth of monolayered chiral film on the quaternary ammonium-modified silicon substrate. The films grew on the substrate surface because of the strong electrostatic interaction between positively charged quaternary ammonium groups and negatively charged phosphate groups of DNA, with subsequent growth to right-handed, vertically aligned, impeller-like helical architectures with left-handed two-dimensional square p4mm-structured DNA chiral packing. The DNA-silica composite films exhibited strong optical activity at 295 nm and in the range of 400-800 nm, corresponding to DNA chiral packing (absorption) and to the helical blade in the impeller (scattering), respectively. Upon removal of DNA templates, the pure inorganic impeller-like helical morphology was maintained; consequently, the scattering-based optical response was blue-shifted approximately 200 nm as a result of a decrease in the effective average refractive index. The hierarchical structures were reflected from the surfaces by cross-polarised light, which confirmed that the films were strongly birefringent, with long-range anisotropy.

  5. Growth of Optically Active Chiral Inorganic Films through DNA Self-Assembly and Silica Mineralisation

    PubMed Central

    Liu, Ben; Han, Lu; Duan, Yingying; Cao, Yunayuan; Feng, Ji; Yao, Yuan; Che, Shunai

    2014-01-01

    The circularly polarized reflection of nature is due to their distinct azimuthally twisted or helical character in the nanostructure of the surface films. Although many chiral inorganic powders have been successfully synthesised, the artificial synthesis of chiral inorganic films is rare. Herein, we reported a facile synthetic route for the growth of monolayered chiral film on the quaternary ammonium-modified silicon substrate. The films grew on the substrate surface because of the strong electrostatic interaction between positively charged quaternary ammonium groups and negatively charged phosphate groups of DNA, with subsequent growth to right-handed, vertically aligned, impeller-like helical architectures with left-handed two-dimensional square p4mm-structured DNA chiral packing. The DNA–silica composite films exhibited strong optical activity at 295 nm and in the range of 400–800 nm, corresponding to DNA chiral packing (absorption) and to the helical blade in the impeller (scattering), respectively. Upon removal of DNA templates, the pure inorganic impeller-like helical morphology was maintained; consequently, the scattering-based optical response was blue-shifted approximately 200 nm as a result of a decrease in the effective average refractive index. The hierarchical structures were reflected from the surfaces by cross-polarised light, which confirmed that the films were strongly birefringent, with long-range anisotropy. PMID:24784912

  6. Calcium phosphate-based organic-inorganic hybrid nanocarriers with pH-responsive on/off switch for photodynamic therapy.

    PubMed

    Nomoto, Takahiro; Fukushima, Shigeto; Kumagai, Michiaki; Miyazaki, Kozo; Inoue, Aki; Mi, Peng; Maeda, Yoshinori; Toh, Kazuko; Matsumoto, Yu; Morimoto, Yuji; Kishimura, Akihiro; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2016-05-26

    Photodynamic therapy (PDT) is a promising treatment modality for malignant tumors in a light-selective manner. To improve the PDT efficacy, numerous kinds of nanocarriers have been developed to deliver photosensitizers (PSs) selectively into the tumor through leaky tumor-associated vasculature. However, the corresponding prolonged retention of the nanocarrier in the bloodstream may lead to unfavorable photochemical damage to normal tissues such as skin. Here, we report an organic-inorganic hybrid nanocarrier with a pH-responsive on/off switch of PDT efficacy. This hybrid nanocarrier is constructed by hydrothermal synthesis after simple mixing of calcium/phosphate ions, chlorin e6 (amphiphilic low molecular weight PS), and poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAsp) copolymers in an aqueous solution. The hybrid nanocarrier possesses a calcium phosphate (CaP) core encapsulating the PSs, which is surrounded by a PEG shielding layer. Under physiological conditions (pH 7.4), the nanocarrier suppressed the photochemical activity of PS by lowering the access of oxygen molecules to the incorporated PS, while PDT efficacy was restored in a pH-responsive manner because of the dissolution of CaP and eventual recovery of access between the oxygen and the PS. Owing to this switch, the nanocarrier reduced the photochemical damage in the bloodstream, while it induced effective PDT efficacy inside the tumor cell in response to the acidic conditions of the endo-/lysosomes. PMID:26971562

  7. Hydrophobic and Metallophobic Surfaces: Highly Stable Non-wetting Inorganic Surfaces Based on Lanthanum Phosphate Nanorods

    NASA Astrophysics Data System (ADS)

    Sankar, Sasidharan; Nair, Balagopal N.; Suzuki, Takehiro; Anilkumar, Gopinathan M.; Padmanabhan, Moothetty; Hareesh, Unnikrishnan Nair S.; Warrier, Krishna G.

    2016-03-01

    Metal oxides, in general, are known to exhibit significant wettability towards water molecules because of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface. Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs), LaPO4 in particular, exhibit without any chemical modification, unique combination of intrinsic properties including remarkable hydrophobicity that could be retained even after exposure to extreme temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO4 as well as mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than 105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete non-wettability and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO4 and other REP ceramics utility in diverse applications.

  8. Hydrophobic and Metallophobic Surfaces: Highly Stable Non-wetting Inorganic Surfaces Based on Lanthanum Phosphate Nanorods.

    PubMed

    Sankar, Sasidharan; Nair, Balagopal N; Suzuki, Takehiro; Anilkumar, Gopinathan M; Padmanabhan, Moothetty; Hareesh, Unnikrishnan Nair S; Warrier, Krishna G

    2016-01-01

    Metal oxides, in general, are known to exhibit significant wettability towards water molecules because of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface. Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs), LaPO4 in particular, exhibit without any chemical modification, unique combination of intrinsic properties including remarkable hydrophobicity that could be retained even after exposure to extreme temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO4 as well as mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than 105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete non-wettability and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO4 and other REP ceramics utility in diverse applications. PMID:26955962

  9. Hydrophobic and Metallophobic Surfaces: Highly Stable Non-wetting Inorganic Surfaces Based on Lanthanum Phosphate Nanorods

    PubMed Central

    Sankar, Sasidharan; Nair, Balagopal N.; Suzuki, Takehiro; Anilkumar, Gopinathan M.; Padmanabhan, Moothetty; Hareesh, Unnikrishnan Nair S.; Warrier, Krishna G.

    2016-01-01

    Metal oxides, in general, are known to exhibit significant wettability towards water molecules because of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface. Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs), LaPO4 in particular, exhibit without any chemical modification, unique combination of intrinsic properties including remarkable hydrophobicity that could be retained even after exposure to extreme temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO4 as well as mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than 105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete non-wettability and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO4 and other REP ceramics utility in diverse applications. PMID:26955962

  10. OsPHF1 Regulates the Plasma Membrane Localization of Low- and High-Affinity Inorganic Phosphate Transporters and Determines Inorganic Phosphate Uptake and Translocation in Rice1[W][OA

    PubMed Central

    Chen, Jieyu; Liu, Yu; Ni, Jun; Wang, Yifeng; Bai, Youhuang; Shi, Jing; Gan, Jian; Wu, Zhongchang; Wu, Ping

    2011-01-01

    PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1 (PHF1) is known to regulate the plasma membrane localization of PHT1;1, a high-affinity inorganic phosphate (Pi) transporter in Arabidopsis (Arabidopsis thaliana). OsPHF1, a rice (Oryza sativa) gene homologous to AtPHF1, was isolated and found to regulate the localization of both low- and high-affinity Pi transporters to the plasma membrane. Three OsPHF1 allelic mutants carrying one-point mutations at the fifth WD-repeat motif and two at the transmembrane helix, respectively, showed arsenate resistance and severely reduced Pi accumulation. The data indicate that mutation of OsPHF1 results in the endoplasmic reticulum retention of the low-affinity Pi transporter OsPT2 and high-affinity Pi transporter OsPT8. Mutation of OsPHF1 also reduced Pi accumulation in plants exhibiting excessive shoot Pi accumulation due to the overexpression of OsPHR2. However, the transcript level of OsPHF1 itself is not controlled by OsPHR2. Overexpression of OsPHF1 increased Pi accumulation in both roots and shoots in a solution culture with Pi-supplied condition. These results indicate that the role of OsPHF1 is unique in the localization of both low- and high-affinity Pi transporters on the plasma membrane in rice and determines Pi uptake and translocation in rice. The similar function of PHF1 required to facilitate PHT1 transit through the endoplasmic reticulum between Arabidopsis and rice provides an example of expectations from what one would deduce from sequence comparisons to extend knowledge from Arabidopsis to crops. PMID:21753117

  11. Phosphate oxygen isotope ratio proxy for specific microbial activity in marine sediments (Peru Margin)

    NASA Astrophysics Data System (ADS)

    Liang, Y.; Blake, R. E.

    2005-12-01

    Oxygen (O) isotope ratios of biogenic apatites have been widely used as paleotemperature and environmental geochemical proxies. With improved knowledge of the phosphate O isotope effects of different P cycling pathways, the δ18O value of inorganic phosphate (δ18OP) has been proposed as a useful proxy and tracer of biological reactions and P cycling in natural environments[1,2,3,4]. Being the only way of removing P from oceanic water, sedimentary P burial is one of the most important processes during biogeochemical cycling of P. The high concentrations of organic matter and pronounced microbial activity at ODP Site 1230 along the Peru Margin result in unusually high interstitial water phosphate concentrations, which provides a unique opportunity to use δ18OP to investigate inorganic phosphate (Pi) regeneration and P cycling pathways in marine sediments. The isotopic measurements of both dissolved inorganic phosphate (DIP) and bulk sediment Pi show that DIP δ18OP values are affected by three different processes, which are all induced by specific microbial activities present in the sediments. In sediments at ~ 65 to 120 mbsf, porewater DIP is derived from dissolved organophosphorus compounds (DOP) through enzymatic degradation pathways, evidenced by both DIP δ18OP values and interstitial water chemistry. Measured porewater DIP δ18OP values also suggest that 4 to 8% of interstitial water DIP reflects regeneration of Pi from Porg by microbially-synthesized enzymes. Throughout the sediment column and especially at ~ 120 to 150 mbsf, DIP is released from the sediments by microbially-induced reductive dissolution of Fe-oxides, which contributes to the overall high DIP concentrations at Site 1230. The third and dominant process controlling measured DIP δ18OP values is microbial turnover of regenerated Pi. The presence of high microbial activities in organic-rich Site 1230 sediments promotes the remobilization of P and affects marine P cycling by potentially enhancing

  12. Structure of human farnesyl pyrophosphate synthase in complex with an aminopyridine bisphosphonate and two molecules of inorganic phosphate

    PubMed Central

    Park, Jaeok; Lin, Yih-Shyan; Tsantrizos, Youla S.; Berghuis, Albert M.

    2014-01-01

    Human farnesyl pyrophosphate synthase (hFPPS) produces farnesyl pyrophos­phate, an isoprenoid essential for a variety of cellular processes. The enzyme has been well established as the molecular target of the nitrogen-containing bisphosphonates (N-BPs), which are best known for their antiresorptive effects in bone but are also known for their anticancer properties. Crystal structures of hFPPS in ternary complexes with a novel bisphosphonate, YS0470, and the secondary ligands inorganic phosphate (Pi), inorganic pyrophosphate (PPi) and isopentenyl pyrophosphate (IPP) have recently been reported. Only the co-binding of the bisphosphonate with either PPi or IPP resulted in the full closure of the C-­terminal tail of the enzyme, a conformational change that is required for catalysis and that is also responsible for the potent in vivo efficacy of N-BPs. In the present communication, a co-crystal structure of hFPPS in complex with YS0470 and two molecules of Pi is reported. The unusually close proximity between these ligands, which was confirmed by anomalous diffraction data, suggests that they interact with one another, with their anionic charges neutralized in their bound state. The structure also showed the tail of the enzyme to be fully disordered, indicating that simultaneous binding of two Pi molecules with a bisphosphonate cannot induce the tail-closing conformational change in hFPPS. Examination of homologous FPPSs suggested that this ligand-dependent tail closure is only conserved in the mammalian proteins. The prevalence of Pi-bound hFPPS structures in the PDB raises a question regarding the in vivo relevance of Pi binding to the function of the enzyme. PMID:24598914

  13. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    SciTech Connect

    Sugama, T.; Pyatina, T.

    2014-11-14

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  14. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    SciTech Connect

    Sugama, T.; Pyatina, T.

    2014-11-01

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  15. Hybrid organic-inorganic crystals based on ammonium dihydrogen phosphate and ammonium salicylate

    NASA Astrophysics Data System (ADS)

    Voronov, A. P.; Salo, V. I.; Puzikov, V. M.; Babenko, G. N.; Roshal, A. D.; Tkachenko, V. F.

    2011-11-01

    ADP-NH 4Sal hybrid crystals are grown from aqueous solutions. The influence of the acidity of the mixed solution on the conditions of co-crystallization of the components is studied. The spectral and scintillation characteristics are determined. Co-crystallization of ammonium salicylate (NH 4Sal) and ammonium dihydrogen phosphate (ADP, NH 4H 2PO 4) is shown to be feasible, the structure of the doping addition being defined by the solution рН. In basic and weak acidic media the hybrid crystals ADP:NH 4Sal are formed in which salicylate anions are located in the interplanar space between the {110}-type planes in the lattice of ADP. The luminescence spectra contain an emission band maximum with λ max=360 nm. In acidic solutions there are ADP:HSal crystals in which salicylic acid molecules captured by the growth macrosteps are located in the interplanar space of the prismatic {100} and pyramidal {101} growth sectors. The luminescence band undergoes bathochromic shift to λmax=400 nm. The sensitivity of ADP:NH 4Sal scintillation crystals to fast neutrons depends on the concentration of ammonium salicylate in ADP matrix. The highest neutron sensitivity is characteristic of the co-doped ADP:NH 4Sal/Tl scintillation crystals.

  16. Influence of an organic and an inorganic additive on the crystallization of dicalcium phosphate dihydrate

    NASA Astrophysics Data System (ADS)

    Anee, T. K.; Meenakshi Sundaram, N.; Arivuoli, D.; Ramasamy, P.; Narayana Kalkura, S.

    2005-12-01

    Dicalcium phosphate dihydrate (DCPD) was crystallized by single diffusion method under physiological pH, in the presence of cobalt and malic acid. The morphology, composition and microstructure of the grown crystals were analyzed using EDTA titration, UV-Visible, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM). These analyses showed that the grown crystals were Co 2+-doped DCPD. The temperature has influenced the dopant entry into DCPD crystals, but the dopant content and temperature were having not much influence on the crystal morphology. In pathological crystallization, the size and morphology are very important since they decide the mode of treatment to adopt. The morphological changes arise when the growth assay is doped with cobalt and malic acid. The effect of malic acid on the crystallization was highly specific, adsorbing on certain crystal faces during growth and producing different morphologies. At higher concentration, the morphology showed a feature frequently encountered in biomineralization, the orientational ordering in [0 0 1], leading to elongated crystals.

  17. Phytic Acid Synthesis and Vacuolar Accumulation in Suspension-Cultured Cells of Catharanthus roseus Induced by High Concentration of Inorganic Phosphate and Cations1[w

    PubMed Central

    Mitsuhashi, Naoto; Ohnishi, Miwa; Sekiguchi, Yoko; Kwon, Yong-Uk; Chang, Young-Tae; Chung, Sung-Kee; Inoue, Yoshinori; Reid, Robert J.; Yagisawa, Hitoshi; Mimura, Tetsuro

    2005-01-01

    We have established a new system for studying phytic acid, myo-inositol hexakisphosphate (InsP6) synthesis in suspension-cultured cells of Catharanthus. InsP6 and other intermediates of myo-inositol (Ins) phosphate metabolism were measured using an ion chromatography method. The detection limit for InsP6 was less than 50 nm, which was sufficient to analyze Ins phosphates in living cells. Synthesis of Ins phosphates was induced by incubation in high inorganic phosphate medium. InsP6 was mainly accumulated in vacuoles and was enhanced when cells were grown in high concentration of inorganic phosphates with the cations K+, Ca2+, or Zn2+. However, there was a strong tendency for InsP6 to accumulate in the vacuole in the presence of Ca2+ and in nonvacuolar compartments when supplied with Zn2+, possibly due to precipitation of InsP6 with Zn2+ in the cytosol. A vesicle transport inhibitor, brefeldin A, stimulated InsP6 accumulation. The amounts of both Ins(3)P1 myo-inositol monophosphate synthase, a key enzyme for InsP6 synthesis, and Ins(1,4,5)P3 kinase were unrelated to the level of accumulation of InsP6. The mechanisms for InsP6 synthesis and localization into vacuoles in plant cells are discussed. PMID:15965017

  18. Proteomic Analysis Provides New Insights in Phosphorus Homeostasis Subjected to Pi (Inorganic Phosphate) Starvation in Tomato Plants (Solanum lycopersicum L.).

    PubMed

    Muneer, Sowbiya; Jeong, Byoung Ryong

    2015-01-01

    Phosphorus is a major nutrient acquired by plants via high-affinity inorganic phosphate (Pi) transporters. To determine the adaptation and homeostasis strategy to Pi starvation, we compared the proteome analysis of tomato leaves that were treated with and without Pi (as KH2PO4) for 10 days. Among 600 reproducible proteins on 2-DE gels 46 of them were differentially expressed. These proteins were involved in major metabolic pathways, including photosynthesis, transcriptional/translational regulations, carbohydrate/energy metabolism, protein synthesis, defense response, and other secondary metabolism. The results also showed that the reduction in photosynthetic pigments lowered P content under -Pi treatments. Furthermore, high-affinity Pi transporters (lePT1 and lePT2) expressed in higher amounts under -Pi treatments. Also, the accumulation of Pi transporters was observed highly in the epidermis and palisade parenchyma under +Pi treatments compared to -Pi treatments. Our data suggested that tomato plants developed reactive oxygen species (ROS) scavenging mechanisms to cope with low Pi content, including the up-regulation of proteins mostly involved in important metabolic pathways. Moreover, Pi-starved tomato plants increased their internal Pi utilization efficiency by increasing the Pi transporter genes and their rational localization. These results thus provide imperative information about how tomato plants respond to Pi starvation and its homeostasis. PMID:26222137

  19. Proteomic Analysis Provides New Insights in Phosphorus Homeostasis Subjected to Pi (Inorganic Phosphate) Starvation in Tomato Plants (Solanum lycopersicum L.)

    PubMed Central

    Muneer, Sowbiya; Jeong, Byoung Ryong

    2015-01-01

    Phosphorus is a major nutrient acquired by plants via high-affinity inorganic phosphate (Pi) transporters. To determine the adaptation and homeostasis strategy to Pi starvation, we compared the proteome analysis of tomato leaves that were treated with and without Pi (as KH2PO4) for 10 days. Among 600 reproducible proteins on 2-DE gels 46 of them were differentially expressed. These proteins were involved in major metabolic pathways, including photosynthesis, transcriptional/translational regulations, carbohydrate/energy metabolism, protein synthesis, defense response, and other secondary metabolism. The results also showed that the reduction in photosynthetic pigments lowered P content under –Pi treatments. Furthermore, high-affinity Pi transporters (lePT1 and lePT2) expressed in higher amounts under –Pi treatments. Also, the accumulation of Pi transporters was observed highly in the epidermis and palisade parenchyma under +Pi treatments compared to –Pi treatments. Our data suggested that tomato plants developed reactive oxygen species (ROS) scavenging mechanisms to cope with low Pi content, including the up-regulation of proteins mostly involved in important metabolic pathways. Moreover, Pi-starved tomato plants increased their internal Pi utilization efficiency by increasing the Pi transporter genes and their rational localization. These results thus provide imperative information about how tomato plants respond to Pi starvation and its homeostasis. PMID:26222137

  20. Relationship between Nitrite Reduction and Active Phosphate Uptake in the Phosphate-Accumulating Denitrifier Pseudomonas sp. Strain JR 12

    PubMed Central

    Barak, Yoram; van Rijn, Jaap

    2000-01-01

    Phosphate uptake by the phosphate-accumulating denitrifier Pseudomonas sp. JR12 was examined with different combinations of electron and carbon donors and electron acceptors. Phosphate uptake in acetate-supplemented cells took place with either oxygen or nitrate but did not take place when nitrite served as the final electron acceptor. Furthermore, nitrite reduction rates by this denitrifier were shown to be significantly reduced in the presence of phosphate. Phosphate uptake assays in the presence of the H+-ATPase inhibitor N,N′-dicyclohexylcarbodiimide (DCCD), in the presence of the uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP), or with osmotic shock-treated cells indicated that phosphate transport over the cytoplasmic membrane of this bacterium was mediated by primary and secondary transport systems. By examining the redox transitions of whole cells at 553 nm we found that phosphate addition caused a significant oxidation of a c-type cytochrome. Based on these findings, we propose that this c-type cytochrome serves as an intermediate in the electron transfer to both nitrite reductase and the site responsible for active phosphate transport. In previous studies with this bacterium we found that the oxidation state of this c-type cytochrome was significantly higher in acetate-supplemented, nitrite-respiring cells (incapable of phosphate uptake) than in phosphate-accumulating cells incubated with different combinations of electron donors and acceptors. Based on the latter finding and results obtained in the present study it is suggested that phosphate uptake in this bacterium is subjected to a redox control of the active phosphate transport site. By means of this mechanism an explanation is provided for the observed absence of phosphate uptake in the presence of nitrite and inhibition of nitrite reduction by phosphate in this organism. The implications of these findings regarding denitrifying, phosphate removal wastewater plants is discussed. PMID

  1. Structural basis for glucose-6-phosphate activation of glycogen synthase

    SciTech Connect

    Baskaran, Sulochanadevi; Roach, Peter J.; DePaoli-Roach, Anna A.; Hurley, Thomas D.

    2010-11-22

    Regulation of the storage of glycogen, one of the major energy reserves, is of utmost metabolic importance. In eukaryotes, this regulation is accomplished through glucose-6-phosphate levels and protein phosphorylation. Glycogen synthase homologs in bacteria and archaea lack regulation, while the eukaryotic enzymes are inhibited by protein kinase mediated phosphorylation and activated by protein phosphatases and glucose-6-phosphate binding. We determined the crystal structures corresponding to the basal activity state and glucose-6-phosphate activated state of yeast glycogen synthase-2. The enzyme is assembled into an unusual tetramer by an insertion unique to the eukaryotic enzymes, and this subunit interface is rearranged by the binding of glucose-6-phosphate, which frees the active site cleft and facilitates catalysis. Using both mutagenesis and intein-mediated phospho-peptide ligation experiments, we demonstrate that the enzyme's response to glucose-6-phosphate is controlled by Arg583 and Arg587, while four additional arginine residues present within the same regulatory helix regulate the response to phosphorylation.

  2. Inactivation of highly activated spinach leaf sucrose-phosphate synthase by dephosphorylation. [Spinacia oleracea

    SciTech Connect

    Huber, J.L. ); Huber, S.C. North Carolina State Univ., Raleigh ); Hite, D.R.C.; Outlaw, W.H. Jr. )

    1991-01-01

    Spinach (Spinacia oleracea L.) leaf sucrose-phosphate synthase (SPS) can be phosphorylated and inactivated in vitro with ({gamma}-{sup 32}P)ATP. Thus, it was surprising to find that SPS, extracted from leaves fed mannose in the light to highly activate the enzyme, could be inactivated in an ATP-independent manner when desalted crude extracts were preincubated at 25{degrees}C before assay. The spontaneous inactivation involved a loss in activity measured with limiting substrate concentrations in the presence of the inhibitor, Pi, without affecting maximum catalytic activity. The spontaneous inactivation was unaffected by exogenous carrier proteins and protease inhibitors, but was inhibited by inorganic phosphate, fluoride, and molybdate, suggesting that a phosphatase may be involved. Okadaic acid, a potent inhibitor of mammalian type 1 and 2A protein phosphatases, had no effect up to 5 micromolar. Inactivation was stimulated about twofold by exogenous Mg{sup 2+} and was relatively insensitive to Ca{sup 2+} and to pH over the range pH 6.5 to 8.5. Radioactive phosphate incorporated into SPS during labeling of excised leaves with ({sup 32}P)Pi (initially in the dark and then in the light with mannose) was lost with time when desalted crude extracts were incubated at 25 C, and the loss in radiolabel was substantially reduced by fluoride. These results provide direct evidence for action of an endogenous phosphatase(s) using SPS as substrate.

  3. INTERACTIVE EFFECTS OF INORGANIC PHOSPHATE NUTRITION AND CARBON DIOXIDE ENRICHMENT ON ASSIMILATE PARTITIONING IN BARLEY ROOTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Metabolite levels and sucrose hydrolyzing enzyme activities were determined between 9- and 17-days after sowing using roots of barley seedlings (Hordeum vulgare L. cv. Brant) with ambient (36 Pa) and elevated (100 Pa) CO2 treatments in controlled environment chambers. Plant growth in elevated CO2 e...

  4. Evidence That a Malate/Inorganic Phosphate Exchange Translocator Imports Carbon across the Leucoplast Envelope for Fatty Acid Synthesis in Developing Castor Seed Endosperm.

    PubMed Central

    Eastmond, P. J.; Dennis, D. T.; Rawsthorne, S.

    1997-01-01

    In this study we examined the processes by which malate and pyruvate are taken up across the leucoplast envelope for fatty acid synthesis in developing castor (Ricinus communis L.) seed endosperm. Malate was taken up by isolated leucoplasts with a concentration dependence indicative of protein-mediated transport. The maximum rate of malate uptake was 704 [plus or minus] 41 nmol mg-1 protein h-1 and the Km was 0.62 [plus or minus] 0.08 mM. In contrast, the rate of pyruvate uptake increased linearly with respect to the substrate concentration and was 5-fold less than malate at a concentration of 5 mM. Malate uptake was inhibited by inorganic phosphate (Pi), glutamate, malonate, succinate, 2-oxoglutarate, and n-butyl malonate, an inhibitor of the mitochondrial malate/Pi-exchange translocator. Back-exchange experiments confirmed that malate was taken up by leucoplasts in counterexchange for Pi. The exchange stoichiometry was 1:1. The rate of malate-dependent fatty acid synthesis by isolated leucoplasts was 3-fold greater than from pyruvate at a concentration of 5 mM and was inhibited by n-butyl malonate. It is proposed that leucoplasts from developing castor endosperm contain a malate/Pi translocator that imports malate for fatty acid synthesis. This type of dicarboxylate transport activity has not been identified previously in plastids. PMID:12223747

  5. Effects of inorganic phosphate analogues on stiffness and unloaded shortening of skinned muscle fibres from rabbit.

    PubMed Central

    Chase, P B; Martyn, D A; Kushmerick, M J; Gordon, A M

    1993-01-01

    1. We examined the effects of aluminofluoride (AlFx) and orthovanadate (Vi), tightly binding analogues of orthophosphate (Pi), on the mechanical properties of glycerinated fibres from rabbit psoas muscle. Maximum Ca(2+)-activated force, stiffness, and unloaded shortening velocity (Vus) were measured under conditions of steady-state inhibition (up to 1 mM of inhibitor) and during the recovery from inhibition. 2. Stiffness was measured using either step or sinusoidal (1 kHz) changes in fibre length. Sarcomere length was monitored continuously by helium-neon laser diffraction during maximum Ca2+ activation. Stiffness was determined from the changes in sarcomere length and the corresponding changes in force. Vus was measured using the slack test method. 3. AlF chi and Vi each reversibly inhibited force, stiffness and Vus. Actively cycling cross-bridges were required for reversal of these inhibitory effects. Recovery from inhibition by AlF chi was 3- to 4-fold slower than that following removal of V1. 4. At various degrees of inhibition, AlF chi and Vi both inhibited steady-state isometric force more than either Vus or stiffness. For both AlF chi and Vi, the relatively greater inhibition of force over stiffness persisted during recovery from steady-state inhibition. We interpret these results to indicate that the cross-bridges with AlF chi or Vi bound are analogous to those which occur early in the cross-bridge cycle. PMID:8487194

  6. The pathway of inorganic-phosphate efflux from isolated liver mitochondria during adenosine triphosphate hydrolysis.

    PubMed

    Tyler, D D

    1980-12-15

    1. The distribution of P(i) between mitochondria and suspending medium during uncoupler-stimulated hydrolysis of ATP by rat liver mitochondria [Tyler (1969) Biochem. J.111, 665-678] has been reinvestigated, by using either mersalyl or N-ethylmaleimide as inhibitors of P(i) transport and either buffered sucrose/EDTA or LiCl/EGTA solutions as suspending medium. More than 75% of the total P(i) liberated was retained in mitochondria treated with either inhibitor at all ATP concentrations tested (0.2-2.5mm). With low ATP concentrations and mersalyl-treated mitochondria incubated in sucrose/EDTA, virtually all the P(i) liberated was retained in the mitochondria. 2. Larger amounts of P(i) appeared in the suspending medium during ATPase activity, despite the presence of N-ethylmaleimide, when LiCl/EGTA was used as suspending medium compared with sucrose/EDTA. Two sources of this P(i) were identified: (a) a slow efflux of P(i) from mitochondria to suspending medium despite the presence of N-ethylmaleimide; (b) a slow ATPase activity insensitive to carboxyatractyloside, which was stimulated by added Mg(2+), partially inhibited by oligomycin or efrapeptin and strongly inhibited by EDTA. 3. It is concluded that liver mitochondria preparations contain two distinct forms of ATPase activity. The major activity is associated with coupled mitochondria of controlled permeability to adenine nucleotides and P(i) and is stimulated strongly by uncoupling agents. The minor activity is associated with mitochondria freely permeable to adenine nucleotides and P(i), is unaffected by uncoupling agents and is activated by endogenous or added Mg(2+). 4. When mitochondria treated with mersalyl were incubated in buffered sucrose solution, almost all the P(i) liberated was recovered in the suspending medium, unless inhibitors of P(i)-induced large-amplitude swelling such as EDTA, EGTA, antimycin, rotenone, nupercaine or Mg(2+) were added. Thus the loss of the specific permeability properties of

  7. The effect of metabolic fuel on force production and resting inorganic phosphate levels in mouse skeletal muscle.

    PubMed Central

    Phillips, S K; Wiseman, R W; Woledge, R C; Kushmerick, M J

    1993-01-01

    1. The effect of different metabolic fuels (glucose, pyruvate and lactate) and no exogenous metabolic fuel on force production was studied in isolated mouse soleus and extensor digitorum longus (EDL) muscles. Force was measured, at 25 degrees C, during isometric tetanic contractions and during contractions with isovelocity stretching and shortening. In parallel experiments, measurements were made of the resting phosphorus metabolite levels using 31P NMR. 2. In soleus muscles, the isometric tetanic force was potentiated with pyruvate (20 mM) as metabolic fuel, compared with glucose (11 mM), by 17.8 +/- 3.6% (mean +/- S.E.M., n = 6). The force was the same with no exogenous metabolic fuel, with glucose, or with lactate as metabolic fuel. The force exerted during shortening was also potentiated by pyruvate and by the same proportion as isometric force. However, during rapid stretching there was no force enhancement with pyruvate. The changes in the force seen with pyruvate are qualitatively similar to those produced when inorganic phosphate (Pi) is lowered in skinned rabbit psoas muscle fibres. 3. We tested whether the Pi content decreased in the presence of pyruvate by measuring resting Pi using 31P NMR spectroscopy. We found that, in soleus muscles, resting Pi was present with glucose and absent with pyruvate as metabolic fuel, and the effect was reversible. 4. EDL muscles produced the same isometric force whether the metabolic fuel was glucose, pyruvate, lactate or if no exogenous metabolic fuel was supplied. EDL muscles already had Pi levels below detectability at rest in glucose. There were no changes in the 31P NMR spectrum with pyruvate as metabolic fuel. 5. It appears therefore that the force potentiation in soleus muscles with pyruvate is due to a lowering of Pi. EDL muscles, which have a very low resting Pi in glucose, therefore have very little potential for force enhancement by this mechanism. PMID:8331580

  8. Phosphate oxygen isotopic evidence for a temperate and biologically active Archaean ocean.

    PubMed

    Blake, Ruth E; Chang, Sae Jung; Lepland, Aivo

    2010-04-15

    Oxygen and silicon isotope compositions of cherts and studies of protein evolution have been interpreted to reflect ocean temperatures of 55-85 degrees C during the early Palaeoarchaean era ( approximately 3.5 billion years ago). A recent study combining oxygen and hydrogen isotope compositions of cherts, however, makes a case for Archaean ocean temperatures being no greater than 40 degrees C (ref. 5). Ocean temperature can also be assessed using the oxygen isotope composition of phosphate. Recent studies show that (18)O:(16)O ratios of dissolved inorganic phosphate (delta(18)O(P)) reflect ambient seawater temperature as well as biological processing that dominates marine phosphorus cycling at low temperature. All forms of life require and concentrate phosphorus, and as a result of biological processing, modern marine phosphates have delta(18)O(P) values typically between 19-26 per thousand (VSMOW), highly evolved from presumed source values of approximately 6-8 per thousand that are characteristic of apatite in igneous rocks and meteorites. Here we report oxygen isotope compositions of phosphates in sediments from the 3.2-3.5-billion-year-old Barberton Greenstone Belt in South Africa. We find that delta(18)O(P) values range from 9.3 per thousand to 19.9 per thousand and include the highest values reported for Archaean rocks. The temperatures calculated from our highest delta(18)O(P) values and assuming equilibrium with sea water with delta(18)O = 0 per thousand (ref. 12) range from 26 degrees C to 35 degrees C. The higher delta(18)O(P) values are similar to those of modern marine phosphate and suggest a well-developed phosphorus cycle and evolved biologic activity on the Archaean Earth. PMID:20393560

  9. Raman spectra of organic (myo-inositol hexakis phosphate) and inorganic P sepctra show pH dependence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding phosphorous fate and transport is in part limited by technical difficulties and/or access to expensive equipment associated with differentiating ortho-phosphate (P) from organic phosphate in complex environmental samples. Myo-inositol hexakis phosphate (IHP) is the most prevalent form...

  10. Bound adenosine 5'-triphosphate formation, bound adenosine 5'-diphosphate and inorganic phosphate retention, and inorganic phosphate oxygen exchange by chloroplast adenosinetriphosphatase in the presence of Ca2+ or Mg2+.

    PubMed

    Wu, D; Boyer, P D

    1986-06-01

    When the heat-activated chloroplast F1 ATPase hydrolyzes [3H, gamma-32P]ATP, followed by the removal of medium ATP, ADP, and Pi, the enzyme has labeled ATP, ADP, and Pi bound to it in about equal amounts. The total of the bound [3H]ADP and [3H]ATP approaches 1 mol/mol of enzyme. Over a 30-min period, most of the bound [32P]Pi falls off, and the bound [3H]ATP is converted to bound [3H]ADP. Enzyme with such remaining tightly bound ADP will form bound ATP from relatively high concentrations of medium Pi with either Mg2+ or Ca2+ present. The tightly bound ADP is thus at a site that retains a catalytic capacity for slow single-site ATP hydrolysis (or synthesis) and is likely the site that participates in cooperative rapid net ATP hydrolysis. During hydrolysis of 50 microM [3H]ATP in the presence of either Mg2+ or Ca2+, the enzyme has a steady-state level of about one bound [3H]ADP per mole of enzyme. Because bound [3H]ATP is also present, the [3H]ADP is regarded as being present on two cooperating catalytic sites. The formation and levels of bound ATP, ADP, and Pi show that reversal of bound ATP hydrolysis can occur with either Ca2+ or Mg2+ present. They do not reveal why no phosphate oxygen exchange accompanies cleavage of low ATP concentrations with Ca2+ in contrast to Mg2+ with the heat-activated enzyme. Phosphate oxygen exchange does occur with either Mg2+ or Ca2+ present when low ATP concentrations are hydrolyzed with the octyl glucoside activated ATPase. Ligand binding properties of Ca2+ at the catalytic site rather than lack of reversible cleavage of bound ATP may underlie lack of oxygen exchange under some conditions. PMID:2873834

  11. Vesicular-arbuscular mycorrhizae and the enzymatic utilization of inorganic phosphate by plant roots: Progress report 1985

    SciTech Connect

    Marx, D. H.

    1985-01-01

    It is well known that phosphorus absorption, especially from soil with low phosphorus levels, by plant roots can be enhanced by mycorrhizal infection. Root cortical cells colonized by vesicular-arbuscular mycorrhizal fungi (VAM) have higher concentrations of phosphorus than noninfected cells. Polyphosphate is the major phosphorus reserve in many fungi and is reported to be present abundantly in young and proliferating arbuscules. We propose that mycorrhizal polyphosphate can be utilized by the VAM-plant symbiont system as a phosphorus donor and an energy source in the glycolytic pathway, possibly after being hydrolyzed to pytrophosphate (PPi). The VAM systems of infected and noninfected roots of sweetgum (Liquidambar styraciflua L.) and onion (Allium cepa L. var. Texas Grand) were used to compare the activity of PPI-dependent phosphofructokinase (PFK), an enzyme utilizing PPi to convert frutose-6-phosphate into fructosel,6-bisphosphate. The ATP-PKF activity was measured also. 1 fig., 3 tabs.

  12. Development of an engineered soil bacterium enabling to convert both insoluble inorganic and organic phosphate into plant available phosphate and its use as a biofertilizer.

    PubMed

    Liu, Lili; Du, Wenya; Luo, Wenyu; Su, Yi; Hui, Jiejie; Ma, Shengwu

    2015-05-01

    Phosphorus (P) is one of the most important nutrient elements for plant growth and metabolism. We previously isolated a P-solubilizing bacterium 9320-SD with the ability to utilize inorganic P and convert it into plant-available P. The present study aims to enhance the P-solubilizing capacity of 9320-SD, as our long-term goal is to develop a more effective P-solubilizing bacterial strain for use as a biofertilizer. In this end, we introduced a bacterial phytase encoding gene into 9320-SD. One randomly selected transformant, SDLiuTP02, was examined for recombinant protein expression and phytase activity, and assessed for its ability to promote plant growth. Our results indicate that SDLiuTP02 is capable of expressing high levels of phytase activity. Importantly, corn seedlings treated with the SDLiuTP02 cell culture exhibited increased rates of photosynthesis, transpiration, and stomatal conductance as well as increased growth rate under laboratory conditions and increased growth rate in pot assays compared to seedlings treated with cell cultures of the parental strain 9320-SD. Field experiments further indicated that application of SDLiuTP02 promoted a greater growth rate in young cucumber plant and a higher foliar chlorophyll level in chop suey greens when compared to 9320-SD treated controls. These results indicate that SDLiuTP02 has the potential to be a more effective P biofertilizer to increase agricultural productivity. PMID:25585914

  13. Catalysis of hydrolysis and nucleophilic substitution at the P-N bond of phosphoimidazolide-activated nucleotides in phosphate buffers

    NASA Technical Reports Server (NTRS)

    Kanavarioti, A.; Rosenbach, M. T.

    1991-01-01

    Phosphoimidazolide-activated derivatives of guanosine and cytidine 5'-monophosphates, henceforth called ImpN's, exhibit enhanced rates of degradation in the presence of aqueous inorganic phosphate in the range 4.0 < or = pH < or = 8.6. This degradation is been attributed to (i) nucleophilic substitution of the imidazolide and (ii) catalysis of the P-N bond hydrolysis by phosphate. The first reaction results in the formation of nucleoside 5'-diphosphate and the second in nucleoside 5'-monophosphate. Analysis of the observed rates as well as the product ratios as a function of pH and phosphate concentration allow distinction between various mechanistic possibilities. The results show that both H2PO4- and HPO4(2-) participate in both hydrolysis and nucleophilic substitution. Statistically corrected biomolecular rate constants indicate that the dianion is 4 times more effective as a general base than the monoanion, and 8 times more effective as nucleophile. The low Bronsted value beta = 0.15 calculated for these phosphate species, presumed to act as general bases in facilitating water attack, is consistent with the fact that catalysis of the hydrolysis of the P-N bond in ImpN's has not been detected before. The beta nuc = 0.35 calculated for water, H2PO4-, HPO4(2-), and hydroxide acting as nucleophiles indicates a more associative transition state for nucleotidyl (O2POR- with R = nucleoside) transfers than that observed for phosphoryl (PO3(2-)) transfers (beta nuc = 0.25). With respect to the stability/reactivity of ImpN's under prebiotic conditions, our study shows that these materials would not suffer additional degradation due to inorganic phosphate, assuming the concentrations of phosphate, Pi, on prebiotic Earth were similar to those in the present oceans ([Pi] approximately 2.25 micromoles).

  14. Glycerolipid biosynthesis in Saccharomyces cerevisiae: sn-glycerol-3-phosphate and dihydroxyacetone phosphate acyltransferase activities.

    PubMed Central

    Schlossman, D M; Bell, R M

    1978-01-01

    Yeast acyl-coenzyme A:dihydroxyacetone-phosphate O-acyltransferase (DHAP acyltransferase; EC 2.3.1.42) was investigated to (i) determine whether its activity and that of acyl-coenzyme A:sn-glycerol-3-phosphate O-acyltransferase (glycerol-P acyltransferase; EC 2.3.1.15) represent dual catalytic functions of a single membranous enzyme, (ii) estimate the relative contributions of the glycerol-P and DHAP pathways for yeast glycerolipid synthesis, and (iii) evaluate the suitability of yeast for future genetic investigations of the eucaryotic glycerol-P and DHAP acyltransferase activities. The membranous DHAP acyltransferase activity showed an apparent Km of 0.79 mM for DHAP, with a Vmax of 5.3 nmol/min per mg, whereas the glycerol-P acyltransferase activity showed an apparent Km of 0.05 mM for glycerol-P, with a Vmax of 3.4 nmol/min per mg. Glycerol-P was a competitive inhibitor (Ki, 0.07 mM) of the DHAP acyltransferase activity, and DHAP was a competitive inhibitor (Ki, 0.91 mM) of the glycerol-P acyltransferase activity. The two acyltransferase activities exhibited marked similarities in their pH dependence, acyl-coenzyme A chain length preference and substrate concentration dependencies, thermolability, and patterns of inactivation by N-ethylmaleimide, trypsin, and detergents. Thus, the data strongly suggest that yeast glycerol-P and DHAP acyltransferase activities represent dual catalytic functions of a single membrane-bound enzyme. Furthermore, since no acyl-DHAP oxidoreductase activity could be detected in yeast membranes, the DHAP pathway for glycerolipid synthesis may not operate in yeast. PMID:25265

  15. Effect of interactions on the nutrient status of a tropical soil treated with green manures and inorganic phosphate fertilizers.

    PubMed

    Bah, Abdul R; Rahman, Zaharah A; Hussin, Aminuddin

    2004-06-01

    Integrated nutrient management systems using plant residues and inorganic P fertilizers have high potential for increasing crop production and ensuring sustainability in the tropics, but their adoption requires in-depth understanding of nutrient dynamics in such systems. This was examined in a highly weathered tropical soil treated with green manures (GMs) and P fertilizers in two experiments conducted in the laboratory and glasshouse. The treatments were factorial combinations of the GMs (Calopogonium caeruleum, Gliricidia sepium, and Imperata cylindrica) and P fertilizers (phosphate rocks [PRs] from North Carolina, China, and Algeria, and triple superphosphate) replicated thrice. Olsen P, mineral N, pH, and exchangeable K, Ca, and Mg were monitored in a laboratory incubation study for 16 months. The change in soil P fractions and available P was also determined at the end of the study. Phosphorus available from the amendments was quantified at monthly intervals for 5 months by 33P-32P double isotopic labeling in the glasshouse using Setaria sphacelata as test crop. The GMs were labeled with 33P to determine their contribution to P taken up by Setaria, while that from the P fertilizers was indirectly measured by labeling the soil with 32P. The P fertilizers hardly changed Olsen P and exchangeable cations during 16 months of incubation. The legume GMs and legume GM+P did not change Olsen P, lowered exchangeable Ca, and increased exchangeable K about threefold (4.5 cmol[+]kg(-1) soil) in the first 4 months, even as large amounts of NH4-N accumulated (approximately 1000 mg kg soil(-1)) and soil pH increased to more than 6.5. Afterwards, Olsen P and exchangeable Ca and Mg increased (threefold) as NH4+-N and soil pH declined. The legume GMs also augmented reversibly sorbed P in Al-P and Fe-P fractions resulting in high residual effect in the soil, while fertilizer-P was irreversibly retained. The GMs increased PR-P utilization by 40 to over 80%, mobilized soil P, and

  16. Shp2 protein tyrosine phosphatase inhibitor activity of estramustine phosphate and its triterpenoid analogs

    PubMed Central

    Scott, Latanya M.; Chen, Liwei; Daniel, Kenyon G.; Brooks, Wesley H.; Guida, Wayne C.; Lawrence, Harshani R.; Sebti, Said M.; Lawrence, Nicholas J.; Wu, Jie

    2010-01-01

    Shp2 protein tyrosine phosphate (PTP) is a novel target for anticancer drug discovery. We identified estramustine phosphate as a Shp2 PTP inhibitor from the National Cancer Institute Approved Oncology Drug set. A focused structure-activity relationship study indicated that the 17- phosphate group is required for the Shp2 PTP inhibitor activity of estramustine phosphate. A search for estramustine phosphate analogs led to identification of two triperpenoids, enoxolone and celastrol, having Shp2 PTP inhibitor activity. With the previously reported PTP1B inhibitor trodusquemine, our study reveals steroids and triterpenoids with negatively charged phosphate, carboxylate, or sulfonate groups as novel pharmacophores of selective PTP inhibitors. PMID:21193311

  17. Evaluation of commonly used methods for the analysis of acid-soluble phosphate in internationally traded inorganic fertilizers.

    PubMed

    Hall, William L; Siegel, Sanford

    2014-01-01

    Several methodologies are used throughout the world to determine phosphate concentration (measured as PO4 and expressed as % P2O5) in fertilizers. Concentrated phosphate materials, including diammonium phosphate (DAP) and monoammonium phosphate (MAP), are traded in large volumes (millions of metric tons) internationally. The International Fertilizer Association (IFA) identified a need to assess the methods currently being used to measure the phosphate content for suitability (scope), accuracy, and repeatability. Even small discrepancies in the expressed P2O5 content can have a major financial impact on buyers and sellers as contracts are settled and import regulations are imposed. The IFA's Technical Committee selected a working group to address issues dealing with harmonization of fertilizer sampling and analytical methodologies. The working group identified phosphate content in DAP and MAP fertilizers as a major concern for commerce. The working group initiated a method screening and comparison project to assess method performance and to determine which methods, if any, could be considered best practice methods and, therefore, be deemed acceptable for use by the industry. In order to systematically review the acceptability of methods for consideration, the task force developed an assessment protocol outlined in a white paper involving three steps: (1) compile all known relevant methods practiced in global fertilizer trade, (2) review and evaluate methods based upon specific evaluation criteria, and (3) compare the methods that most closely fit the evaluation criteria by multilaboratory analysis of unknown materials for accuracy and repeatability. Six methods were evaluated for analysis of total phosphate in concentrated phosphate products. From these methods, four were determined to be acceptable as best practice methods. The study members proposed three of the methods, while a fourth method was commonly used among the participating laboratories. This publication

  18. INORGANIC PYROPHOSPHATASE OF DESULFOVIBRIO DESULFURICANS.

    PubMed

    AKAGI, J M; CAMPBELL, L L

    1963-09-01

    Akagi, J. M. (University of Illinois, Urbana) and L. Leon Campbell. Inorganic pyrophosphatase of Desulfovibrio desulfuricans. J. Bacteriol. 86:563-568. 1963.-The inorganic pyrophosphatase of Desulfovibrio desulfuricans was purified 136-fold by (NH(4))(2)SO(4) and ethanol fractionation and diethylaminoethyl cellulose chromatography. Mg(++) or Mn(++) was required for optimal activity; Co(++) was only 65% as effective as Mg(++). The optimal ratio of Mg(++) to pyrophosphate was 1.0 at pH 8.0. The K(s) for the pyrophosphatase was found to be in the region of 1.9 x 10(-3)m. Sulfhydryl inhibitors and sodium fluoride had no effect on enzyme activity at a concentration of 10(-3)m. The purified enzyme did not hydrolyze adenosine triphosphate, glycerol phosphate, diphenyl phosphate, or p-nitrophenyl phosphate. Thermal stability studies showed that the enzyme is rapidly inactivated at temperatures above 40 C. PMID:14066437

  19. Removal of lead from aqueous solutions by activated phosphate.

    PubMed

    Mouflih, M; Aklil, A; Sebti, S

    2005-03-17

    The potential of using activated phosphate as a new adsorbent for the removal of Pb from aqueous solutions was investigated. The kinetic of lead adsorption and the adsorption process were compared for natural phosphate (NP) and activated phosphate (AP). The results indicate that equilibrium was established in about 1h for NP and 3 h for AP. The effect of the pH was examined in the range 2-6. The maximum removal obtained is between two and three for NP and between three and four for AP. The maximum adsorption capacities at 25 degrees C are 155.04 and 115.34 mg/g for AP and NP, respectively. The effect of temperature has been carried out at 25, 35 and 45 degrees C. The data obtained from adsorption isotherms of lead at different temperatures fit to linear form of Langmuir adsorption equation. The thermodynamic parameters such as enthalpy (DeltaH), free energy (DeltaG) and entropy (DeltaS) were calculated. They show that adsorption of lead on NP and AP is an endothermic process more effective at high temperatures. These results show that AP is a good adsorbent for heavy metals from aqueous solutions and could be used as a purifier for water and wastewater. PMID:15752864

  20. Faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart related to cytosolic inorganic phosphate (Pi) accumulation.

    PubMed

    Korzeniewski, Bernard

    2016-08-01

    A model of the cell bioenergetic system was used to compare the effect of oxidative phosphorylation (OXPHOS) deficiencies in a broad range of moderate ATP demand in skeletal muscle and heart. Computer simulations revealed that kinetic properties of the system are similar in both cases despite the much higher mitochondria content and "basic" OXPHOS activity in heart than in skeletal muscle, because of a much higher each-step activation (ESA) of OXPHOS in skeletal muscle than in heart. Large OXPHOS deficiencies lead in both tissues to a significant decrease in oxygen consumption (V̇o2) and phosphocreatine (PCr) and increase in cytosolic ADP, Pi, and H(+) The main difference between skeletal muscle and heart is a much higher cytosolic Pi concentration in healthy tissue and much higher cytosolic Pi accumulation (level) at low OXPHOS activities in the former, caused by a higher PCr level in healthy tissue (and higher total phosphate pool) and smaller Pi redistribution between cytosol and mitochondria at OXPHOS deficiency. This difference does not depend on ATP demand in a broad range. A much greater Pi increase and PCr decrease during rest-to-moderate work transition in skeletal muscle at OXPHOS deficiencies than at normal OXPHOS activity significantly slows down the V̇o2 on-kinetics. Because high cytosolic Pi concentrations cause fatigue in skeletal muscle and can compromise force generation in skeletal muscle and heart, this system property can contribute to the faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart. Shortly, skeletal muscle with large OXPHOS deficiencies becomes fatigued already during low/moderate exercise. PMID:27283913

  1. Evidence for a "metabolically inactive" inorganic phosphate pool in adenosine triphosphate synthase reaction using localized 31P saturation transfer magnetic resonance spectroscopy in the rat brain at 11.7 T.

    PubMed

    Tiret, Brice; Brouillet, Emmanuel; Valette, Julien

    2016-09-01

    With the increased spectral resolution made possible at high fields, a second, smaller inorganic phosphate resonance can be resolved on (31)P magnetic resonance spectra in the rat brain. Saturation transfer was used to estimate de novo adenosine triphosphate synthesis reaction rate. While the main inorganic phosphate pool is used by adenosine triphosphate synthase, the second pool is inactive for this reaction. Accounting for this new pool may not only help us understand (31)P magnetic resonance spectroscopy metabolic profiles better but also better quantify adenosine triphosphate synthesis. PMID:27354096

  2. Characterization of Streptococcus pneumoniae 5-enolpyruvylshikimate 3-phosphate synthase and its activation by univalent cations.

    PubMed

    Du, W; Wallis, N G; Mazzulla, M J; Chalker, A F; Zhang, L; Liu, W S; Kallender, H; Payne, D J

    2000-01-01

    The aroA gene (Escherichia coli nomenclature) encoding 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase from the gram-positive pathogen Streptococcus pneumoniae has been identified, cloned and overexpressed in E. coli, and the enzyme purified to homogeneity. It was shown to catalyze a reversible conversion of shikimate 3-phosphate (S3P) and phosphoenolpyruvate (PEP) to EPSP and inorganic phosphate. Activation by univalent cations was observed in the forward reaction, with NH+4, Rb+ and K+ exerting the greatest effects. Km(PEP) was lowered by increasing [NH+4] and [K+], whereas Km(S3P) rose with increasing [K+], but fell with increasing [NH+4]. Increasing [NH+4] and [K+] resulted in an overall increase in kcat. Glyphosate (GLP) was found to be a competitive inhibitor with PEP, but the potency of inhibition was profoundly affected by [NH+4] and [K+]. For example, increasing [NH+4] and [K+] reduced Ki(GLP versus PEP) up to 600-fold. In the reverse reaction, the enzyme catalysis was less sensitive to univalent cations. Our analysis included univalent cation concentrations comparable with those found in bacterial cells. Therefore, the observed effects of these metal ions are more likely to reflect the physiological behavior of EPSP synthase and also add to our understanding of how to inhibit this enzyme in the host organism. As there is a much evidence to suggest that EPSP synthase is essential for bacterial survival, its discovery in the serious gram-positive pathogen S. pneumoniae and its inhibition by GLP indicate its potential as a broad-spectrum antibacterial target. PMID:10601870

  3. Peroxymonosulfate activation by phosphate anion for organics degradation in water.

    PubMed

    Lou, Xiaoyi; Wu, Liuxi; Guo, Yaoguang; Chen, Chuncheng; Wang, Zhaohui; Xiao, Dongxue; Fang, Changling; Liu, Jianshe; Zhao, Jincai; Lu, Shuyu

    2014-12-01

    Activation of peroxygens is a critical method to generate oxidative species, but often consumes additional chemical reagents and/or energy. Here we report a novel and efficient activation reaction for peroxymonosulfate (PMS) by phosphate anions (PBS). The PBS/PMS coupled system, at neutral pH, is able to decompose efficiently even mineralize a variety of organic pollutants, such as Acid Orange 7, Rhodamine B and 2,4,6-trichlorophenol. In contrast, no measurable degradation was observed when the PMS was replaced by other peroxygens (i.e. hydrogen peroxide and peroxydisulfate). Both PMS and PBS are indispensable for the oxidative degradation of pollutants. Increasing pH and concentrations of PMS and PBS significantly accelerate the degradation of organics. It is proposed that OH would be the major radical for contamination degradation at pH 7.0 through the radical quenching experiments. This work provides a new way of PMS activation for decontamination at neutral pH, in particular for phosphate-rich wastewater treatment. PMID:25303463

  4. Inorganic phosphate-triggered release of anti-cancer arsenic trioxide from a self-delivery system: an in vitro and in vivo study

    NASA Astrophysics Data System (ADS)

    Chen, Fei-Yan; Yi, Jing-Wei; Gu, Zhe-Jia; Tang, Bin-Bing; Li, Jian-Qi; Li, Li; Kulkarni, Padmakar; Liu, Li; Mason, Ralph P.; Tang, Qun

    2016-03-01

    On-demand drug delivery is becoming feasible via the design of either exogenous or endogenous stimulus-responsive drug delivery systems. Herein we report the development of gadolinium arsenite nanoparticles as a self-delivery platform to store, deliver and release arsenic trioxide (ATO, Trisenox), a clinical anti-cancer drug. Specifically, unloading of the small molecule drug is triggered by an endogenous stimulus: inorganic phosphate (Pi) in the blood, fluid, and soft or hard tissue. Kinetics in vitro demonstrated that ATO is released with high ON/OFF specificity and no leakage was observed in the silent state. The nanoparticles induced tumor cell apoptosis, and reduced cancer cell migration and invasion. Plasma pharmacokinetics verified extended retention time, but no obvious disturbance of phosphate balance. Therapeutic efficacy on a liver cancer xenograft mouse model was dramatically potentiated with reduced toxicity compared to the free drug. These results suggest a new drug delivery strategy which might be applied for ATO therapy on solid tumors.On-demand drug delivery is becoming feasible via the design of either exogenous or endogenous stimulus-responsive drug delivery systems. Herein we report the development of gadolinium arsenite nanoparticles as a self-delivery platform to store, deliver and release arsenic trioxide (ATO, Trisenox), a clinical anti-cancer drug. Specifically, unloading of the small molecule drug is triggered by an endogenous stimulus: inorganic phosphate (Pi) in the blood, fluid, and soft or hard tissue. Kinetics in vitro demonstrated that ATO is released with high ON/OFF specificity and no leakage was observed in the silent state. The nanoparticles induced tumor cell apoptosis, and reduced cancer cell migration and invasion. Plasma pharmacokinetics verified extended retention time, but no obvious disturbance of phosphate balance. Therapeutic efficacy on a liver cancer xenograft mouse model was dramatically potentiated with reduced

  5. Opening of the mitochondrial permeability transition pore by uncoupling or inorganic phosphate in the presence of Ca2+ is dependent on mitochondrial-generated reactive oxygen species.

    PubMed

    Kowaltowski, A J; Castilho, R F; Vercesi, A E

    1996-01-01

    In this study, we show that mitochondrial membrane permeability transition in Ca(2+)-loaded mitochondria treated with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) or inorganic phosphate (P(i)) is preceded by enhanced production of H2O2. This production is inhibited either by ethylene glycobis(b-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA) or Mg2+, but not by cyclosporin A. Permeability transition is prevented either by EGTA, catalase or dithiothreitol, suggesting the involvement of Ca2+, H2O2 and oxidation of membrane protein thiols in this mechanism. When mitochondria are incubated under anaerobiosis, no permeabilization or H2O2 production occurs. Based on these results we conclude that mitochondrial permeability transition induced by P(i) or FCCP-uncoupling is dependent on mitochondrial-generated reactive oxygen species. PMID:8549822

  6. The effect of antidepressive drugs and some related compounds on the levels of adenine nucleotides, inorganic phosphate and phosphocreatine in the rat brain

    PubMed Central

    Lewis, J. J.; Van Petten, G. R.

    1963-01-01

    The effects upon levels of adenine nucleotides, phosphocreatine and inorganic phosphate of iproniazid, isoniazid, phenelzine, pheniprazine, tranylcypromine, harmine, imipramine, amitriptyline, orphenadrine, diphenhydramine and cocaine have been studied. With the exception of harmine and diphenhydramine, each of these compounds increased the brain level of adenosine triphosphate and, with the exception of imipramine and cocaine, the level of adenosine diphosphate decreased. Harmine had no effect on levels of adenine nucleotides and, in the case of diphenhydramine, the level of adenosine diphosphate increased and the level of adenosine triphosphate tended to decrease. There appears to be a relationship between the ability of the drugs to cause behavioural signs of central nervous stimulation and to produce an increase in the adenosine triphosphate/diphosphate ratio. This effect may be a factor in the action of antidepressive drugs. PMID:19108178

  7. Transketolase activity modulates glycerol-3-phosphate levels in Escherichia coli.

    PubMed

    Vimala, A; Harinarayanan, R

    2016-04-01

    Transketolase activity provides an important link between the metabolic pathways of glycolysis and pentose phosphate shunt and catalyzes inter-conversions between pentose phosphates and glycolytic intermediates. It is widely conserved in life forms. A genetic screen for suppression of the growth defect of Escherichia coli tktA tktB mutant in LB medium revealed two mutations, one that rendered the glpK expression constitutive and another that inactivated deoB. Characterizing these mutations aided in uncovering the role of ribose-5-P (a transketolase substrate) as an inhibitor of glycerol assimilation and de novo glycerol-3-P synthesis. Using lacZ fusions, we show that ribose-5-P enhances GlpR-mediated repression of the glpFKX operon and inhibits glycerol assimilation. Electrophoretic Mobility Shift Assay (EMSA) showed ribose-5-P made the DNA-GlpR complex less sensitive to the inducer glycerol-3-P. In addition to inhibition of glycerol assimilation, obstruction of ribose-5-P metabolism retards growth from glycerol-3-P limitation. Glucose helps to overcome this limitation through a mechanism involving catabolite repression. To our knowledge, this report is the first to show ribose-5-P can modulate glycerol-3-P concentration in the cell by regulation of glycerol assimilation as well as its de novo synthesis. This regulation could be prevalent in other organisms. PMID:26691989

  8. TEMPERATURE-HYDROSTATIC PRESSURE STUDIES ON PARTIALLY PURIFIED INORGANIC PYROPHOSPHATASE ACTIVITY.

    PubMed

    MORITA, R Y; MATHEMEIER, P F

    1964-12-01

    Morita, Richard Y. (Oregon State University, Corvallis), and Paul F. Mathemeier. Temperature-hydrostatic pressure studies on partially purified inorganic pyrophosphatase activity. J. Bacteriol. 88:1667-1671. 1964.-Partially purified inorganic pyrophosphatase from Bacillus stearothermophilus demonstrated increased activity at 90 C with hydrostatic pressures of 100 to 1,100 atm. At 90 C, optimal activity was at 700 atm. No enzyme activity could be demonstrated at 100 C at 1 atm; however, at 105 C moderate hydrostatic pressures favored the enzyme reaction, resulting in increased activity. The increased enzyme activity is explained on the basis of pressure counteracting the molecular volume increase which results from elevated temperature. Thermal denaturation studies at 90 C show inorganic pyrophosphatase to be more stable in the presence of cofactor than substrate, and indicate an enyzme-cofactor intermediate in the hydrolysis. PMID:14240955

  9. Inorganic fractions in extracellular polymeric substance extracted from activated sludge and biofilm samples by different methods.

    PubMed

    Zhang, Leiyan; Geng, Jinju; Ding, Lili; Ren, Hongqiang

    2012-01-01

    This study highlighted the inorganic fractions in the extracellular polymeric substance (EPS) extract from two activated sludges and one biofilm. Nine EPS extraction methods (centrifugation, sonication, cation exchange resin (CER) + sonication, CER, heating, formaldehyde + heating, formaldehyde + NaOH, ethanol and EDTA) were used in the study. The EPS extracts had large inorganic fractions, which ranged from 28% to 94% of the EPS dry weight. The EPS inorganic fraction was dependent on the source of the sludge and wastewater, the kinds of bacteria and the extraction method. The EPS extracts obtained by heating and sonication had smaller inorganic fractions than those obtained by centrifugation. The compositions of the inorganic fraction of EPS extracts obtained with CER and sonication + CER showed similar trends. The chemical extraction methods could contaminate the inorganic composition of EPS extracts by impurities, carrying over of the extractant itself or by changing the pH of the solution. Ethanol was the most effective extractant for obtaining inorganic ions. PMID:22828296

  10. Oxygen isotope ratios of PO4: An inorganic indicator of enzymatic activity and P metabolism and a new biomarker in the search for life

    PubMed Central

    Blake, Ruth E.; Alt, Jeffrey C.; Martini, Anna M.

    2001-01-01

    The distinctive relations between biological activity and isotopic effect recorded in biomarkers (e.g., carbon and sulfur isotope ratios) have allowed scientists to suggest that life originated on this planet nearly 3.8 billion years ago. The existence of life on other planets may be similarly identified by geochemical biomarkers, including the oxygen isotope ratio of phosphate (δ18Op) presented here. At low near-surface temperatures, the exchange of oxygen isotopes between phosphate and water requires enzymatic catalysis. Because enzymes are indicative of cellular activity, the demonstration of enzyme-catalyzed PO4–H2O exchange is indicative of the presence of life. Results of laboratory experiments are presented that clearly show that δ18OP values of inorganic phosphate can be used to detect enzymatic activity and microbial metabolism of phosphate. Applications of δ18Op as a biomarker are presented for two Earth environments relevant to the search for extraterrestrial life: a shallow groundwater reservoir and a marine hydrothermal vent system. With the development of in situ analytical techniques and future planned sample return strategies, δ18Op may provide an important biosignature of the presence of life in extraterrestrial systems such as that on Mars. PMID:11226207

  11. Novel, inorganic composites using porous, alkali-activated, aluminosilicate binders

    NASA Astrophysics Data System (ADS)

    Musil, Sean

    Geopolymers are an inorganic polymeric material composed of alumina, silica, and alkali metal oxides. Geopolymers are chemical and fire resistant, can be used as refractory adhesives, and are processed at or near ambient temperature. These properties make geopolymer an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. Reinforcements can then be chosen based on the resulting properties to tailor the geopolymer matrix composites to a specific application condition. Geopolymer matrix composites combine the ease of processing of polymer matrix composites with the high temperature capability of ceramic matrix composites. This study incorporated particulate, unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel(TM) 720) and single crystal mullite fibers, then the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and show excellent creep resistance up to 1400°C. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000-1400°C.

  12. High levels of the type III inorganic phosphate transporter PiT1 (SLC20A1) can confer faster cell adhesion

    SciTech Connect

    Kongsfelt, Iben Boutrup; Byskov, Kristina; Pedersen, Lasse Ebdrup; Pedersen, Lene

    2014-08-01

    The inorganic phosphate transporter PiT1 (SLC20A1) is ubiquitously expressed in mammalian cells. We recently showed that overexpression of human PiT1 was sufficient to increase proliferation of two strict density-inhibited cell lines, murine fibroblastic NIH3T3 and pre-osteoblastic MC3T3-E1 cells, and allowed the cultures to grow to higher cell densities. In addition, upon transformation NIH3T3 cells showed increased ability to form colonies in soft agar. The cellular regulation of PiT1 expression supports that cells utilize the PiT1 levels to control proliferation, with non-proliferating cells showing the lowest PiT1 mRNA levels. The mechanism behind the role of PiT1 in increased cell proliferation is not known. We, however, found that compared to control cells, cultures of NIH3T3 cells overexpressing PiT1 upon seeding showed increased cell number after 24 h and had shifted more cells from G0/G1 to S+G2/M within 12 h, suggesting that an early event may play a role. We here show that expression of human PiT1 in NIH3T3 cells led to faster cell adhesion; this effect was not cell type specific in that it was also observed when expressing human PiT1 in MC3T3-E1 cells. We also show for NIH3T3 that PiT1 overexpression led to faster cell spreading. The final total numbers of attached cells did, however, not differ between cultures of PiT1 overexpressing cells and control cells of neither cell type. We suggest that the PiT1-mediated fast adhesion potentials allow the cells to go faster out of G0/G1 and thereby contribute to their proliferative advantage within the first 24 h after seeding. - Highlights: • Effects of elevated levels of the inorganic phosphate transporter PiT1 were studied. • The density-inhibited murine cell lines NIH3T3 and MC3T3-E1 showed faster adhesion. • NIH3T3 cells showed faster spreading. • We suggest that the faster adhesion/spreading contributes to faster proliferation.

  13. A sup 31 P NMR study of mitochondrial inorganic phosphate visibility: Effects of Ca sup 2+ , Mn sup 2+ , and the pH gradient

    SciTech Connect

    Hutson, S.M.; Williams, G.D.; Berkich, D.A.; LaNoue, K.F.; Briggs, R.W. )

    1992-02-11

    The effects of external pH, temperature, and Ca{sup 2+} and Mn{sup 2+} concentrations on the compartmentation and NMR visibility of inorganic phosphate (P{sub i}) were studied in isolated rat liver mitochondria respiring on succinate and glutamate. Mitochondrial matrix P{sub i} is totally visible by NMR at 8C and at low external concentrations of P{sub i}. However, when the external P{sub i} concentration is increased above 7 mM, the pH gradient decreases, the amount of matrix P{sub i} increases, and the fraction not observed by NMR increases. Raising the temperature to 25C also decreases the pH gradient and the P{sub i} fraction observed by NMR. At physiologically relevant concentrations, Ca{sup 2+} and Mn{sup 2+} do not seem to play a major role in matrix P{sub i} NMR invisibility. For Ca{sup 2+} concentrations above 30 nmol/mg of protein, formation of insoluble complexes will cause loss of P{sub i} signal intensity. For Mn{sup 2+} concentrations above 2 nmol/mg of protein, the P{sub i} peak can be broadened sufficiently to preclude detection of a high-resolution signal. The results indicate that mitochondrial matrix P{sub i} should be mostly observable up to 25C by high-resolution NMR. While the exact nature of the NMR-invisible phosphate in perfused or in vivo liver is yet to be determined, better success at detecting and resolving both P{sub i} pools by NMR is indicated at high field, low temperature, and optimized pulsing conditions.

  14. Functional expression of PHO1 to the Golgi and trans-Golgi network and its role in export of inorganic phosphate.

    PubMed

    Arpat, A Bulak; Magliano, Pasqualina; Wege, Stefanie; Rouached, Hatem; Stefanovic, Aleksandra; Poirier, Yves

    2012-08-01

    Arabidopsis thaliana PHO1 is primarily expressed in the root vascular cylinder and is involved in the transfer of inorganic phosphate (Pi) from roots to shoots. To analyze the role of PHO1 in transport of Pi, we have generated transgenic plants expressing PHO1 in ectopic A. thaliana tissues using an estradiol-inducible promoter. Leaves treated with estradiol showed strong PHO1 expression, leading to detectable accumulation of PHO1 protein. Estradiol-mediated induction of PHO1 in leaves from soil-grown plants, in leaves and roots of plants grown in liquid culture, or in leaf mesophyll protoplasts, was all accompanied by the specific release of Pi to the extracellular medium as early as 2-3 h after addition of estradiol. Net Pi export triggered by PHO1 induction was enhanced by high extracellular Pi and weakly inhibited by the proton-ionophore carbonyl cyanide m-chlorophenylhydrazone. Expression of a PHO1-GFP construct complementing the pho1 mutant revealed GFP expression in punctate structures in the pericycle cells but no fluorescence at the plasma membrane. When expressed in onion epidermal cells or in tobacco mesophyll cells, PHO1-GFP was associated with similar punctate structures that co-localized with the Golgi/trans-Golgi network and uncharacterized vesicles. However, PHO1-GFP could be partially relocated to the plasma membrane in leaves infiltrated with a high-phosphate solution. Together, these results show that PHO1 can trigger Pi export in ectopic plant cells, strongly indicating that PHO1 is itself a Pi exporter. Interestingly, PHO1-mediated Pi export was associated with its localization to the Golgi and trans-Golgi networks, revealing a role for these organelles in Pi transport. PMID:22449068

  15. Synthesis and structural characterization of a new chiral porous hybrid organic–inorganic material based on γ-zirconium phosphates and L-(+)-phosphoserine

    SciTech Connect

    Alhendawi, Hussein M.H.

    2013-05-01

    In the present work, a chiral layered derivative of γ-zirconium phosphate (γ-ZrP) containing L-(+)-phosphoserine (γ-ZrP-PS*) covalently attached to inorganic layers has been prepared by means of topotactic exchange reaction. This organic–inorganic derivative is characterized by X-ray diffractometry, Solid {sup 13}C–NMR and FT-IR spectrophotometries and thermal analyses. A maximum level of topotactic replacement of 20% is achieved. Under both the acidic environment of the interlayer region of γ-ZrP and the acidic synthesis conditions, the hydrolysis of the ester bond of PS* is expected to take place to some extent. For this reason, it was impossible to exceed the recent percentage, which in turn reflects the relative moderate stability of the above mentioned bond under these conditions. In order to be more certain with regard to an expected further hydrolysis for this bond after separation, a sample of γ-ZrP-PS* was stored in a desiccator over a saturated solution of BaCl{sub 2} (90% relative humidity) for three months, and then the sample re-analyzed once again. Surprisingly, the results show that the sample still keeps almost the same level of exchange (i.e., 20%). Second, it is revealed that the sample almost gives the same spectroscopic and thermal behavior. This could be attributed to the less acidic character of the partially exchanged inorganic layers of the sample in comparison with that of the precursor γ-ZrP. Therefore, the PS* molecules persist and stay there into the interlayer gallery without further hydrolysis. - Graphical abstract: • Red: oxygen • White: zirconium • Cyan: carbon • Yellow: phosphorus • Blue: nitrogen. Highlights: • L-(+)-Phosphoserine (PS*) is exchanged with γ-ZrP by means of topotactic exchange. • The maximum exchange level is 20%. • γ-ZrP is functionalized with chiral amino acid group. • γ-ZrP-PS* has large chiral space for huge guest molecules to be intercalated.

  16. DIFFERENTIAL ACTIVATION OF AP-1 IN HUMAN BLADDER EPITHELIAL CELLS BY INORGANIC AND METHYLATED ARSENICALS

    EPA Science Inventory

    Differential Activation of AP-1 in Human Bladder Epithelial Cells by Inorganic and Methylated Arsenicals

    Zuzana Drobna, Ilona Jaspers, David J. Thomas, and Miroslav Styblo

    ABSTRACT

    Epidemiological studies have linked chronic ingestion of drinking water contai...

  17. A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.

    2008-08-01

    Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH+4, Mg2+, Ca2+, Cl-, Br-, NO-3, HSO-4, and SO2-4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

  18. A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, Th.

    2008-03-01

    Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42- as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol + water + salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

  19. Characterization of the cross-bridge force-generating step using inorganic phosphate and BDM in myofibrils from rabbit skeletal muscles

    PubMed Central

    Tesi, C; Colomo, F; Piroddi, N; Poggesi, C

    2002-01-01

    The inhibitory effects of inorganic phosphate (Pi) on isometric force in striated muscle suggest that in the ATPase reaction Pi release is coupled to force generation. Whether Pi release and the power stroke are synchronous events or force is generated by an isomerization of the quaternary complex of actomyosin and ATPase products (AM.ADP.Pi) prior to the following release of Pi is still controversial. Examination of the dependence of isometric force on [Pi] in rabbit fast (psoas; 5-15 °C) and slow (soleus; 15-20 °C) myofibrils was used to test the two-step hypothesis of force generation and Pi release. Hyperbolic fits of force-[Pi] relations obtained in fast and slow myofibrils at 15 °C produced an apparent asymptote as [Pi]∞ of 0.07 and 0.44 maximal isometric force (i.e. force in the absence of Pi) in psoas and soleus myofibrils, respectively, with an apparent Kd of 4.3 mm in both. In each muscle type, the force-[Pi] relation was independent of temperature. However, 2,3-butanedione 2-monoxime (BDM) decreased the apparent asymptote of force in both muscle types, as expected from its inhibition of the force-generating isomerization. These data lend strong support to models of cross-bridge action in which force is produced by an isomerization of the AM.ADP.Pi complex immediately preceding the Pi release step. PMID:12015429

  20. The Sodium-Dependent Inorganic Phosphate Transporter SLC34A1 (NaPi-IIa) Is Not Localized in the Mouse Brain

    PubMed Central

    Larsson, Max; Morland, Cecilie; Poblete-Naredo, Irais; Biber, Jürg; Danbolt, Niels Christian; Gundersen, Vidar

    2011-01-01

    The sodium-dependent inorganic phosphate transporter NaPi-IIa is expressed in the kidney. Here, the authors used a polyclonal antiserum raised against NaPi-IIa- and NaPi-IIa-deficient mice to characterize its expression in nervous tissue. Western blots showed that a NaPi-IIa immunoreactive band (~90 kDa) was only present in wild-type kidney membranes and not in kidney knockout or wild-type brain membranes. In the water-soluble fraction of wild-type and knockout brains, another band (~50 kDa) was observed; this band was not detected in the kidney. Light and electron microscopic immunohistochemistry using the NaPi-IIa antibodies showed immunolabeling of kidney tubules in wild-type but not knockout mice. In the brain, labeling of presynaptic nerve terminals was present also in NaPi-IIa-deficient mice. This labeling pattern was also produced by the NaPi-IIa preimmune serum. The authors conclude that the polyclonal antiserum is specific toward NaPi-IIa in the kidney, but in the brain, immunolabeling is caused by a cross-reaction of the antiserum with an unknown cytosolic protein that is not present in the kidney. This tissue-specific cross-reactivity highlights a potential pitfall when validating antibody specificity using knockout mouse-derived tissue other than the specific tissue of interest and underlines the utility of specificity testing using preimmune sera. PMID:21606201

  1. Surface runoff pollution by cattle slurry and inorganic fertilizer spreading: chemical oxygen demand, ortho-phosphates, and electrical conductivity levels for different buffer strip lengths.

    PubMed

    Núñez-Delgado, A; López-Periago, E; Quiroga-Lago, F; Díaz-Fierros Viqueira, F

    2001-01-01

    As a way of dealing with the removal of pollutants from farming practices generated wastewater in the EU, we investigate the effect of spreading cattle slurry and inorganic fertiliser on 8 x 5 m2 and 8 x 3 m2 areas, referred to surface runoff chemical oxygen demand (COD), ortho-phosphates (o-P) and electrical conductivity (EC) levels, and the efficiency of grass buffer strips of various lengths in removing pollutants from runoff. The experimental plot was a 15% sloped Lolium perenne pasture. Surface runoff was generated by means of a rainfall simulator working at 47 mm h-1 rainfall intensity. Runoff was sampled by using Gerlach-type troughs situated 2, 4, 6 and 8 m downslope from the amended areas. During the first rainfall simulation, COD, o-P and EC levels were consistently higher in the slurry zone, more evidently in the larger amended area. During the second and third rainfall simulations, concentration and mass levels show a downslope drift into the buffer zones, with no clear buffer strip length attenuation. Correlation between runoff and mass drift is clearly higher in the slurry zone. Percentage attenuation in COD and o-P levels, referred to initial slurry concentrations--including rainfall dilution--were higher than 98%, and higher than 90% for EC. PMID:11496670

  2. Protein-inorganic hybrid nanoflowers

    NASA Astrophysics Data System (ADS)

    Ge, Jun; Lei, Jiandu; Zare, Richard N.

    2012-07-01

    Flower-shaped inorganic nanocrystals have been used for applications in catalysis and analytical science, but so far there have been no reports of `nanoflowers' made of organic components. Here, we report a method for creating hybrid organic-inorganic nanoflowers using copper (II) ions as the inorganic component and various proteins as the organic component. The protein molecules form complexes with the copper ions, and these complexes become nucleation sites for primary crystals of copper phosphate. Interaction between the protein and copper ions then leads to the growth of micrometre-sized particles that have nanoscale features and that are shaped like flower petals. When an enzyme is used as the protein component of the hybrid nanoflower, it exhibits enhanced enzymatic activity and stability compared with the free enzyme. This is attributed to the high surface area and confinement of the enzymes in the nanoflowers.

  3. Lack of relationship between activity of intestinal alkaline phosphatase and calcium or phosphate absorption.

    PubMed

    Asteggiano, C; Tolosa, N; Pereira, R; Moreno, J; Cañas, F

    1981-01-01

    The effects of vitamin D3 and the aqueous extract of Solanum malacoxylon on intestinal alkaline phosphatase and tissue phosphate content were studied on rachitic chicks treated with large doses of ethane-1-hydroxy-1,1 diphosphonate (EHDP). The EHDP treatment blocks the increase of intestinal calcium or phosphate absorption induced by the vitamin D3, while it has no effects on the rise of intestinal alkaline phosphatase activity or the increment in tissue phosphate content. The lack of correlation between the increment of alkaline phosphatase and that of Ca or phosphate absorption in vitamin D3 plus EHDP treated chicks excludes a participation of the alkaline phosphatase in the mechanism of Ca or P intestinal absorption. The Ca or phosphorus absorption are elicited specifically by 1,25-(OH)2-D3, while alkaline phosphatase activity and phosphate tissue concentration respond to a broader spectrum of stimuli. PMID:6316731

  4. Phosphoinositide and Inositol Phosphate Analysis in Lymphocyte Activation

    PubMed Central

    Sauer, Karsten; Huang, Yina Hsing; Lin, Hongying; Sandberg, Mark; Mayr, Georg W.

    2015-01-01

    Lymphocyte antigen receptor engagement profoundly changes the cellular content of phosphoinositide lipids and soluble inositol phosphates. Among these, the phosphoinositides phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) play key signaling roles by acting as pleckstrin homology (PH) domain ligands that recruit signaling proteins to the plasma membrane. Moreover, PIP2 acts as a precursor for the second messenger molecules diacylglycerol and soluble inositol 1,4,5-trisphosphate (IP3), essential mediators of PKC, Ras/Erk, and Ca2+ signaling in lymphocytes. IP3 phosphorylation by IP3 3-kinases generates inositol 1,3,4,5-tetrakisphosphate (IP4), an essential soluble regulator of PH domain binding to PIP3 in developing T cells. Besides PIP2, PIP3, IP3, and IP4, lymphocytes produce multiple other phosphoinositides and soluble inositol phosphates that could have important physiological functions. To aid their analysis, detailed protocols that allow one to simultaneously measure the levels of multiple different phosphoinositide or inositol phosphate isomers in lymphocytes are provided here. They are based on thin layer, conventional and high-performance liquid chromatographic separation methods followed by radiolabeling or non-radioactive metal-dye detection. Finally, less broadly applicable nonchromatographic methods for detection of specific phosphoinositide or inositol phosphate isomers are discussed. Support protocols describe how to obtain pure unstimulated CD4+CD8+ thymocyte populations for analyses of inositol phosphate turnover during positive and negative selection, key steps in T cell development. PMID:19918943

  5. Lithium Iron Phosphate Cell Performance Evaluations for Lunar Extravehicular Activities

    NASA Technical Reports Server (NTRS)

    Reid, Concha

    2007-01-01

    Lithium-ion battery cells are being evaluated for their ability to provide primary power and energy storage for NASA s future Exploration missions. These missions include the Orion Crew Exploration Vehicle, the Ares Crew Launch Vehicle Upper Stage, Extravehicular Activities (EVA, the advanced space suit), the Lunar Surface Ascent Module (LSAM), and the Lunar Precursor and Robotic Program (LPRP), among others. Each of these missions will have different battery requirements. Some missions may require high specific energy and high energy density, while others may require high specific power, wide operating temperature ranges, or a combination of several of these attributes. EVA is one type of mission that presents particular challenges for today s existing power sources. The Portable Life Support System (PLSS) for the advanced Lunar surface suit will be carried on an astronaut s back during eight hour long sorties, requiring a lightweight power source. Lunar sorties are also expected to occur during varying environmental conditions, requiring a power source that can operate over a wide range of temperatures. Concepts for Lunar EVAs include a primary power source for the PLSS that can recharge rapidly. A power source that can charge quickly could enable a lighter weight system that can be recharged while an astronaut is taking a short break. Preliminary results of Al23 Ml 26650 lithium iron phosphate cell performance evaluations for an advanced Lunar surface space suit application are discussed in this paper. These cells exhibit excellent recharge rate capability, however, their specific energy and energy density is lower than typical lithium-ion cell chemistries. The cells were evaluated for their ability to provide primary power in a lightweight battery system while operating at multiple temperatures.

  6. INFLUENCE OF SUBSTRATE-COFACTOR RATIOS ON PARTIALLY PURIFIED INORGANIC PYROPHOSPHATASE ACTIVITY AT ELEVATED TEMPERATURES.

    PubMed

    MATHEMEIER, P F; MORITA, R Y

    1964-12-01

    Mathemeier, Paul F. (Oregon State University, Corvallis), and Richard Y. Morita. Influence of substrate-cofactor ratios on partially purified inorganic pyrophosphatase activity at elevated temperatures. J. Bacteriol. 88:1661-1666. 1964.-Inorganic pyrophosphatase of Bacillus stearothermophilus was studied for optimal substrate-cofactor ratios at 60 to 100 C. Mg(++) was the primary cofactor, and Co(++) resulted in 50% enzyme activity at 60 C. The pH optima differed for the Mg(++) activated and Co(++) activated pyrophosphatase. At 80 C and above, Co(++) replaced Mg(++) as the optimal cofactor in the enzyme reaction. The optimal ratio of pyrophosphate to Mg(++) varied from 2 to 0.25, dependent on enzyme concentration. The optimal pyrophosphate-cobalt ratio was constant at 1.0. The enzyme catalyzed appreciable pyrophosphate hydrolysis at 95 C. PMID:14240954

  7. alpha-Tocopheryl phosphate – an active lipid mediator?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The vitamin E (alpha-tocopherol, alphaT) derivative, alpha-tocopheryl phosphate (alphaTP), is detectable in small amounts in plasma, tissues, and cultured cells. Studies done in vitro and in vivo suggest that alphaT can become phosphorylated and alphaTP dephosphorylated, suggesting the existence of ...

  8. Development of pillared M(IV) phosphate phosphonate inorganic organic hybrid ion exchange materials for applications in separations found in the nuclear fuel cycle

    NASA Astrophysics Data System (ADS)

    Burns, Jonathan David

    This dissertation focuses on key intergroup and intragroup separations found in the back end of the nuclear fuel cycle, specifically americium from lanthanides and americium from other actinides, most importantly americium from curium. Our goal is to implement a liquid-solid separation process to reduce waste and risk of contamination by the development of metal(IV) phosphate phosphonate inorganic organic hybrid ion exchange materials with the ideal formula of M(O6P2C6H4)0.5 (O3POA) ·nH2O, where M = Zr or Sn, A = H or Na. These materials have previously shown to have high affinity for Ln, this work will expand on the previous studies and provide methods for the above target separation, exploiting oxidation state and ion charge to drive the separation process. The optimum hydrothermal reaction conditions were determined by adjusting parameters such as reaction temperature and time, as well as the phosphonate to phosphate (pillar-to-spacer) ligands ratio. Following these results four bulk syntheses were performed and their ion exchange properties were thoroughly examined. Techniques such as inductively coupled mass spectrometry and liquid scintillation counting were used to determine the affinity of the materials towards Na+, Cs+, Ca2+, Sr 2+, Ni2+, Nd3+, Sm3+, Ho3+, Yb3+, NpO2+, Pu4+, PuO22+, Am3+, AmO2+, and Cm3+. Separation factors in the thousands have been observed for intergroup separations of the Ln from the alkali, alkaline earth, and low valent transition metals. A new method for Am oxidation was developed, which employed Na 2S2O8 as the oxidizing agent and Ca(OCl) 2 as the stabilizing agent for AmO2+ synthesis. Separation factors of 30-60 for Nd3+ and Eu3+ from AmO2+, as well as 20 for Cm3+ from AmO2+ were observed at pH 2. The work herein shows that a liquid-solid separation can be carried out for these difficult separations by means of oxidation and ion exchange.

  9. Polycarboxylic acids as network modifiers for water durability improvement of inorganic-organic hybrid tin-silico-phosphate low-melting glasses

    SciTech Connect

    Menaa, Bouzid . E-mail: bouzidmenaa@noncry.kuicr.kyoto-u.ac.jp; Mizuno, Megumi; Takahashi, Masahide . E-mail: masahide@noncry.kuicr.kyoto-u.ac.jp; Tokuda, Yomei; Yoko, Toshinobu

    2006-02-15

    We investigated the water durability of the inorganic-organic hybrid tin-silico-phosphate glasses Me{sub 2}SiO-SnO-P{sub 2}O{sub 5} (Me designs the organic methyl group) doped with organic acids (salicylic acid (SA), tartaric acid (TA), citric acid (Canada) and butane tetracarboxylic acid (BTCA)) containing one or more of carboxylic groups per molecule. The structure, thermal properties and durability of the final glasses obtained via a non-aqueous acid-base reaction were discussed owing to the nature and the concentration of the acid added. {sup 29}Si magic angle spinning (MAS) NMR and {sup 31}P MAS NMR spectra, respectively, showed clearly a modification of the network in the host glass matrix of the Me{sub 2}SiO-SnO-P{sub 2}O{sub 5} system. The polycondensation enhancement to form -P-O-Si-O-P- linkages (PSP) and the increase of the Q {sup 2} unit (two bridging oxygens per phosphorus atom) over the Q {sup 3} unit (three bridging oxygens per phosphorus atom) as a function of the acid in the order SA

  10. Hypoxia-inducible factor-1 plays a role in phosphate-induced vascular smooth muscle cell calcification.

    PubMed

    Mokas, Sophie; Larivière, Richard; Lamalice, Laurent; Gobeil, Stéphane; Cornfield, David N; Agharazii, Mohsen; Richard, Darren E

    2016-09-01

    Medial vascular calcification is a common complication of chronic kidney disease (CKD). Although elevated inorganic phosphate stimulates vascular smooth muscle cell (VSMC) osteogenic transdifferentiation and calcification, the mechanisms involved in their calcification during CKD are not fully defined. Because hypoxic gene activation is linked to CKD and stimulates bone cell osteogenic differentiation, we used in vivo and in vitro rodent models to define the role of hypoxic signaling during elevated inorganic phosphate-induced VSMC calcification. Cell mineralization studies showed that elevated inorganic phosphate rapidly induced VSMC calcification. Hypoxia strongly enhanced elevated inorganic phosphate-induced VSMC calcification and osteogenic transdifferentiation, as seen by osteogenic marker expression. Hypoxia-inducible factor-1 (HIF-1), the key hypoxic transcription factor, was essential for enhanced VSMC calcification. Targeting HIF-1 expression in murine VSMC blocked calcification in hypoxia with elevated inorganic phosphate while HIF-1 activators, including clinically used FG-4592/Roxadustat, recreated a procalcifying environment. Elevated inorganic phosphate rapidly activated HIF-1, even in normal oxygenation; an effect mediated by HIF-1α subunit stabilization. Thus, hypoxia synergizes with elevated inorganic phosphate to enhance VSMC osteogenic transdifferentiation. Our work identifies HIF-1 as an early CKD-related pathological event, prospective marker, and potential target against vascular calcification in CKD-relevant conditions. PMID:27470678

  11. Relationship between Salivary Alkaline Phosphatase Enzyme Activity and The Concentrations of Salivary Calcium and Phosphate Ions

    PubMed Central

    Jazaeri, Mina; Malekzadeh, Hosein; Abdolsamadi, Hamidreza; Rezaei-Soufi, Loghman; Samami, Mohammad

    2015-01-01

    Although salivary alkaline phosphatase (ALP) can balance deand remineralization processes of enamel, there is no evidence regarding its effects on the concentrations of calcium and phosphate in saliva. The present study aims to determine the relationship between salivary ALP activity and the concentrations of calcium and phosphate in saliva. In this cross-sectional study, we evaluated salivary markers in 120 males, ages 19 to 44 years. All participants provided 5 mL of unstimulated whole saliva and the level of enzyme activity as well as calcium and phosphate concentrations were measured using a colorimetric method. Data were gathered and analyzed by statistical package for social sciences (SPSS) 13.00 using Pearson correlation test. A p value of <0.05 was considered statistically significant. The mean age of participants in the present study was 32.95 ± 8.09 years. The mean pH of saliva was 6.65 ± 0.62. Salivary parameters included average ALP activity (5.04 ± 1.866 U/dL), calcium (4.77 ± 0.877 mg/dL) and phosphate (10.38 ± 2.301 mg/dL). Pearson correlation test showed no significant relationship between ALP activity and calcium and phosphate concentrations in saliva (p>0.05). According to the results of the present study, there was no significant relation between salivary ALP activity and calcium and phosphate concentrations in saliva. However, further research is highly recommended. PMID:25870846

  12. Relationship between Salivary Alkaline Phosphatase Enzyme Activity and The Concentrations of Salivary Calcium and Phosphate Ions.

    PubMed

    Jazaeri, Mina; Malekzadeh, Hosein; Abdolsamadi, Hamidreza; Rezaei-Soufi, Loghman; Samami, Mohammad

    2015-01-01

    Although salivary alkaline phosphatase (ALP) can balance deand remineralization processes of enamel, there is no evidence regarding its effects on the concentrations of calcium and phosphate in saliva. The present study aims to determine the relationship between salivary ALP activity and the concentrations of calcium and phosphate in saliva. In this cross-sectional study, we evaluated salivary markers in 120 males, ages 19 to 44 years. All participants provided 5 mL of unstimulated whole saliva and the level of enzyme activity as well as calcium and phosphate concentrations were measured using a colorimetric method. Data were gathered and analyzed by statistical package for social sciences (SPSS) 13.00 using Pearson correlation test. A p value of <0.05 was considered statistically significant. The mean age of participants in the present study was 32.95 ± 8.09 years. The mean pH of saliva was 6.65 ± 0.62. Salivary parameters included average ALP activity (5.04 ± 1.866 U/dL), calcium (4.77 ± 0.877 mg/dL) and phosphate (10.38 ± 2.301 mg/dL). Pearson correlation test showed no significant relationship between ALP activity and calcium and phosphate concentrations in saliva (p>0.05). According to the results of the present study, there was no significant relation between salivary ALP activity and calcium and phosphate concentrations in saliva. However, further research is highly recommended. PMID:25870846

  13. Metabolic regulation in tylosin-producing Streptomyces fradiae: phosphate control of tylosin biosynthesis.

    PubMed Central

    Vu-Trong, K; Bhuwapathanapun, S; Gray, P P

    1981-01-01

    The effects of increased concentration of inorganic phosphate on the biosynthesis of tylosin, the level of the intracellular adenylates, the energy charge, and the activities of enzymes involved in the synthesis of tylonolide precursors were studied in Streptomyces fradiae NRRL 2702. No metabolic response was observed when elevated levels of inorganic phosphate were added in idiophase. Increased initial levels of inorganic phosphate suppressed tylosin production and markedly increased the levels of the adenylates, although the adenylate energy charge was unchanged. Higher growth and glucose uptake rates were also observed. The activities of methylmalonyl-coenzyme A carboxyltransferase (EC 2.1.3.1) and propionyl-coenzyme A carboxylase (EC 6.4.1.3) were suppressed by the increased concentration of inorganic phosphate. The results indicated that the rate of tylosin synthesis was inversely related to the absolute level of the adenylates rather than to the energy charge. PMID:7347556

  14. Insights into the activation mechanism of class I HDAC complexes by inositol phosphates

    PubMed Central

    Watson, Peter J.; Millard, Christopher J.; Riley, Andrew M.; Robertson, Naomi S.; Wright, Lyndsey C.; Godage, Himali Y.; Cowley, Shaun M.; Jamieson, Andrew G.; Potter, Barry V. L.; Schwabe, John W. R.

    2016-01-01

    Histone deacetylases (HDACs) 1, 2 and 3 form the catalytic subunit of several large transcriptional repression complexes. Unexpectedly, the enzymatic activity of HDACs in these complexes has been shown to be regulated by inositol phosphates, which bind in a pocket sandwiched between the HDAC and co-repressor proteins. However, the actual mechanism of activation remains poorly understood. Here we have elucidated the stereochemical requirements for binding and activation by inositol phosphates, demonstrating that activation requires three adjacent phosphate groups and that other positions on the inositol ring can tolerate bulky substituents. We also demonstrate that there is allosteric communication between the inositol-binding site and the active site. The crystal structure of the HDAC1:MTA1 complex bound to a novel peptide-based inhibitor and to inositol hexaphosphate suggests a molecular basis of substrate recognition, and an entropically driven allosteric mechanism of activation. PMID:27109927

  15. Intrinsic activation: the relationship between biomass inorganic content and porosity formation during pyrolysis.

    PubMed

    Stratford, James P; Hutchings, Tony R; de Leij, Frans A A M

    2014-05-01

    The utility of pyrolytic carbons is closely related to their porosity and surface area, there is a clear benefit to the development of biomass pyrolysis processes which produce highly porous carbons. The results presented in this work demonstrate that by using biomass precursors with high inorganic content along with specified process conditions, carbons can be consistently produced with specific surface areas between 900 and 1600 m(2)/g. Results from 12 different source materials show that the formation of increased porosity in pyrolytic carbons is strongly associated with the presence of inorganic elements in the precursors including: magnesium, potassium and sulfur. It was found that pyrolysis of macro-algae can produce especially high specific surface area carbons (mean: 1500 m(2)/g), without externally applied activating agents. Using cheap readily available agricultural residues such as oilseed rape straw, pyrolytic carbons can be produced with specific surface areas of around 950 m(2)/g. PMID:24632632

  16. A Relationship Between Microbial Activity in Soils and Phosphate Levels in Tributaries to Lake Champlain

    NASA Astrophysics Data System (ADS)

    Larose, R.; Lee, S.; Lane, T.

    2015-12-01

    Lake Champlain is a large natural freshwater lake. It forms the western boundary of Vermont and drains over half of the state. It is bordered by the state of New York on its western side and drains to the north into Quebec, Canada. Lake Champlain is the source of fresh drinking water for over quarter of a million people and provides for the livelihoods and recreational opportunities of many well beyond its borders. The health of this lake is important. During the summer month's algae blooms plague the lake. These unsightly growths, which affect other aquatic organisms, are the result of excess phosphate flowing into the lake from many sources. Examining whether there is a relationship between microbial activity in the soils bordering tributaries to Lake Champlain and phosphate levels in those tributaries sheds insight into the origins and paths by which phosphate moves into Lake Champlain. Understanding the how phosphate moves into the water system may assist in mitigation efforts.Total Phosphate levels and Total Suspended Solids were measured in second and third order streams in the Lake Champlain Basin over a three-year period. In addition microbial activity was measured within the toe, bank and upland riparian zone areas of these streams during the summer months. In general in areas showing greater microbial activity in the soil(s) there were increased levels of phosphate in the streams.

  17. The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and Aspergillus niger phytase

    NASA Astrophysics Data System (ADS)

    Sperber, C. v.; Tamburini, F.; Brunner, B.; Bernasconi, S. M.; Frossard, E.

    2015-03-01

    Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (IP6) is an important form of Porg in many soils. The enzymatic hydrolysis of IP6 by phytase yields plant available inorganic phosphate (Pi) and less phosphorylated inositol derivates as products. The hydrolysis of organic P-compounds by phosphatases leaves an isotopic imprint on the oxygen isotope composition (δ18O) of released Pi, which might be used to trace P in the environment. This study aims at determining the effect of phytase on the oxygen isotope composition of released Pi. For this purpose, enzymatic assays with histidine acid phytases from wheat and Aspergillus niger were prepared using IP6, adenosine 5'monophosphate (AMP) and glycerophosphate (GPO4) as substrates. For a comparison to the δ18O of Pi released by other extracellular enzymes, enzymatic assays with acid phosphatases from potato and wheat germ with IP6 as substrate were prepared. During the hydrolysis of IP6 by phytase, four Pi are released, and one oxygen atom from water is incorporated into each Pi. This incorporation of oxygen from water into Pi is subject to an apparent inverse isotopic fractionation (ϵ ∼ 6 to 10‰), which is similar to that imparted by acid phosphatase from potato during the hydrolysis of IP6 (ϵ ∼ 7‰) where less than three Pi are released. The incorporation of oxygen from water into Pi during the hydrolysis of AMP and GPO4 by phytase yielded a normal isotopic fractionation (ϵ ∼ -12‰), again similar to values reported for acid phosphatases from potato and wheat germ. We attribute this similarity in ɛ to the same amino acid sequence motif (RHGXRXP) at the active site of these enzymes, which leads to similar reaction mechanisms. We suggest that the striking substrate-dependency of

  18. Kinetic Characterization of Spinach Leaf Sucrose-Phosphate Synthase 1

    PubMed Central

    Amir, Jacob; Preiss, Jack

    1982-01-01

    The spinach (Spinacia oleracea) leaf sucrose-phosphate synthase was partially purified via DEAE-cellulose chromatography, and its kinetic properties were studied. Fructose-6-phosphate saturation curves were sigmoidal, while UDPglucose saturation curves were hyperbolic. At subsaturating concentrations of fructose-6-phosphate, 1,5 anhydroglucitol-6-phosphate had a stimulatory effect on enzyme activity, suggesting multiple and interacting fructose-6-phosphate sites on sucrose-phosphate synthase. The concentrations required for 50% of maximal activity were 3.0 millimolar and 1.3 millimolar, respectively, for fructose-6-phosphate and UDPglucose. The enzyme was not stimulated by divalent cations. Inorganic phosphate proved to be a potent inhibitor, particularly at low concentrations of substrate. Phosphate inhibition was competitive with UDPglucose, and its Ki was determined to be 1.75 millimolar. Sucrose phosphate, the product of the reaction, was also shown to be a competitive inhibitor towards UDPglucose concentration and had Ki of 0.4 millimolar. The kinetic results suggest that spinach leaf sucrose-phospahte synthase is a regulatory enzyme and that its activity is modulated by the concentrations of phosphate, fructose-6-phosphate, and UDPglucose occurring in the cytoplasm of the leaf cell. PMID:16662338

  19. Sphingomyelinase D Activity in Model Membranes: Structural Effects of in situ Generation of Ceramide-1-Phosphate

    PubMed Central

    Stock, Roberto P.; Brewer, Jonathan; Wagner, Kerstin; Ramos-Cerrillo, Blanca; Duelund, Lars; Jernshøj, Kit Drescher; Olsen, Lars Folke; Bagatolli, Luis A.

    2012-01-01

    The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1) ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate) can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2) the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3) in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes. PMID:22558302

  20. Regeneration of spent powdered activated carbon saturated with inorganic ions by cavitation united with ion exchange method.

    PubMed

    Li, Gang; Gao, Hong; Li, Yansheng; Yang, Huixin

    2011-06-01

    Using ion exchange resin as transfer media, regenerate powdered activated carbon (PAC) adsorbed inorganic ions by cavitation to enhance the transfer; we studied how the regeneration time and the mass ratio of resin and PAC influence the regeneration rate respectively through re-adsorption. The result showed that the effective regeneration of PAC saturated with inorganic ions was above 90% using ion exchange resin as media and transfer carrier, the quantity of PAC did not reduced but activated in the process. PMID:25084579

  1. Circadian Regulation of Sucrose Phosphate Synthase Activity in Tomato by Protein Phosphatase Activity.

    PubMed Central

    Jones, T. L.; Ort, D. R.

    1997-01-01

    Sucrose phosphate synthase (SPS), a key enzyme in sucrose biosynthesis, is regulated by protein phosphorylation and shows a circadian pattern of activity in tomato. SPS is most active in its dephosphorylated state, which normally coincides with daytime. Applying okadaic acid, a potent protein phosphatase inhibitor, prevents SPS activation. More interesting is that a brief treatment with cycloheximide, a cytoplasmic translation inhibitor, also prevents the light activation of SPS without any effect on the amount of SPS protein. Cordycepin, an inhibitor of transcript synthesis and processing, has the same effect. Both of these inhibitors also prevent the activation phase of the circadian rhythm in SPS activity. Conversely, cycloheximide and cordycepin do not prevent the decline in circadian SPS activity that normally occurs at night. These observations indicate that SPS phosphatase activity but not SPS kinase activity is controlled, directly or indirectly, at the level of gene expression. Taken together, these data imply that there is a circadian rhythm controlling the transcription of a protein phosphatase that subsequently dictates the circadian rhythm in SPS activity via effects on this enzyme's phosphorylation state. PMID:12223667

  2. Physicochemical characteristics and sorption capacities of heavy metal ions of activated carbons derived by activation with different alkyl phosphate triesters

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Liu, Hai; Yang, Shaokun; Zhang, Jian; Zhang, Chenglu; Wu, Haiming

    2014-10-01

    Five alkyl phosphate triesters (APTEs), including trimethyl phosphate (TMP), triethyl phosphate (TEP), triisopropyl phosphate (TPP), tributyl phosphate (TBP) and trioctyl phosphate (TOP), were used as activating agents for preparing activated carbons (AC-APTEs) with high surface acidity and metal ion sorption capacity. N2 adsorption/desorption isotherms, surface morphologies, elemental compositions, results of Boehm's titration and sorption capacities of heavy metal ions of the carbons were investigated. AC-APTEs contained much more acidic groups and exhibited much less surface area (<500 m2/g) in comparison with activated carbon (AC-PPA, 1145 m2/g) obtained from phosphoric acid activation. For the AC-APTEs, AC-TOP had the highest surface area (488 m2/g), AC-TMP showed the highest yield (41.1%), and AC-TBP possessed the highest acidic groups (2.695 mmol/g), oxygen content (47.0%) and metal ion sorption capacities (40.1 mg/g for Ni(II) and 53.5 mg/g for Cd(II)). For the carbons, AC-APTEs showed much larger Ni(II) and Cd(II) sorption capacities than AC-PPA, except AC-TPP. The differences of the carbons in the physicochemical and sorption properties suggested surface chemistry of the carbons was the main factor influencing their sorption capacities whereas the pore structure played a secondary role.

  3. Attenuation of Phosphate Starvation Responses by Phosphite in Arabidopsis1

    PubMed Central

    Ticconi, Carla A.; Delatorre, Carla A.; Abel, Steffen

    2001-01-01

    When inorganic phosphate is limiting, Arabidopsis has the facultative ability to metabolize exogenous nucleic acid substrates, which we utilized previously to identify insensitive phosphate starvation response mutants in a conditional genetic screen. In this study, we examined the effect of the phosphate analog, phosphite (Phi), on molecular and morphological responses to phosphate starvation. Phi significantly inhibited plant growth on phosphate-sufficient (2 mm) and nucleic acid-containing (2 mm phosphorus) media at concentrations higher than 2.5 mm. However, with respect to suppressing typical responses to phosphate limitation, Phi effects were very similar to those of phosphate. Phosphate starvation responses, which we examined and found to be almost identically affected by both anions, included changes in: (a) the root-to-shoot ratio; (b) root hair formation; (c) anthocyanin accumulation; (d) the activities of phosphate starvation-inducible nucleolytic enzymes, including ribonuclease, phosphodiesterase, and acid phosphatase; and (e) steady-state mRNA levels of phosphate starvation-inducible genes. It is important that induction of primary auxin response genes by indole-3-acetic acid in the presence of growth-inhibitory Phi concentrations suggests that Phi selectively inhibits phosphate starvation responses. Thus, the use of Phi may allow further dissection of phosphate signaling by genetic selection for constitutive phosphate starvation response mutants on media containing organophosphates as the only source of phosphorus. PMID:11706178

  4. Role of phosphate on stability and catalase mimetic activity of cerium oxide nanoparticles.

    PubMed

    Singh, Ragini; Singh, Sanjay

    2015-08-01

    Cerium oxide nanoparticles (CeNPs) have been recently shown to scavenge reactive oxygen and nitrogen species (ROS and RNS) in different experimental model systems. CeNPs (3+) and CeNPs (4+) have been shown to exhibit superoxide dismutase (SOD) and catalase mimetic activity, respectively. Due to their nanoscale dimension, CeNPs are expected to interact with the components of biologically relevant buffers and medium, which could alter their catalytic properties. We have demonstrated earlier that CeNPs (3+) interact with phosphate and lose the SOD activity. However, very little is known about the interaction of CeNPs (4+) with the phosphate and other anions, predominantly present in biological buffers and their effects on the catalase mimetic-activity of these nanoparticles. In this study, we report that catalase mimetic-activity of CeNPs (4+) is resistant to the phosphate anions, pH changes and composition of cell culture media. Given the abundance of phosphate anions in the biological system, it is likely that internalized CeNPs would be influenced by cytoplasmic and nucleoplasmic concentration of phosphate. PMID:26011425

  5. Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

    PubMed Central

    Schröder, Heinz C; Müller, Werner E G

    2014-01-01

    Summary Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications. PMID:24991497

  6. Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone.

    PubMed

    Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G

    2014-01-01

    Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications. PMID:24991497

  7. A facile stable-isotope dilution method for determination of sphingosine phosphate lyase activity.

    PubMed

    Suh, Jung H; Eltanawy, Abeer; Rangan, Apoorva; Saba, Julie D

    2016-01-01

    A new technique for quantifying sphingosine phosphate lyase activity in biological samples is described. In this procedure, 2-hydrazinoquinoline is used to convert (2E)-hexadecenal into the corresponding hydrazone derivative to improve ionization efficiency and selectivity of detection. Combined utilization of liquid chromatographic separation and multiple reaction monitoring-mass spectrometry allows for simultaneous quantification of the substrate S1P and product (2E)-hexadecenal. Incorporation of (2E)- d5-hexadecenal as an internal standard improves detection accuracy and precision. A simple one-step derivatization procedure eliminates the need for further extractions. Limits of quantification for (2E)-hexadecenal and sphingosine-1-phosphate are 100 and 50fmol, respectively. The assay displays a wide dynamic detection range useful for detection of low basal sphingosine phosphate lyase activity in wild type cells, SPL-overexpressing cell lines, and wild type mouse tissues. Compared to current methods, the capacity for simultaneous detection of sphingosine-1-phosphate and (2E)-hexadecenal greatly improves the accuracy of results and shows excellent sensitivity and specificity for sphingosine phosphate lyase activity detection. PMID:26408264

  8. Mechanisms for solubilization of various insoluble phosphates and activation of immobilized phosphates in different soils by an efficient and salinity-tolerant Aspergillus niger strain An2.

    PubMed

    Li, Xiaolong; Luo, Lijin; Yang, Jinshui; Li, Baozhen; Yuan, Hongli

    2015-03-01

    Mechanisms for solubilization of different types of phosphates and activation of immobilized phosphates in different types of soils by an efficient fungal strain An2 were explored and evaluated in this study. An2 was isolated from a Chinese cabbage rhizosphere soil and identified as Aspergillus niger. It could fast release up to 1722, 2066, and 2356 mg L(-1) of soluble phosphorus (P) from 1 % Ca3(PO4)2, Mg3(PO4)2, and AlPO4 (Ca-P, Mg-P, and Al-P) and 215 and 179 mg L(-1) from 0.5 % FePO4 and rock phosphate (Fe-P and RP), respectively. HPLC assay demonstrated that An2 mainly secreted oxalic acid to solubilize Ca-P, Mg-P, Al-P, and Fe-P whereas secreted tartaric acid to solubilize RP. Furthermore, An2 could tolerate salinity up to 4 % NaCl without impairing its phosphate-solubilizing ability. The simulation experiments validated that An2 was able to effectively activate immobilized phosphates in general calcareous, acidic, as well as saline-alkali soils with high total P content. This study shows new insights into the mechanisms for microbial solubilization of different types of phosphates and supports the future application of strain An2 in different types of soils to effectively activate P for plants. PMID:25561059

  9. CADMIUM PHOSPHATE GLASS

    DOEpatents

    Carpenter, H.W.; Johnson, P.D.

    1963-04-01

    A method of preparing a cadmium phosphate glass that comprises providing a mixture of solid inorganic compounds of cadmuim and phosphate having vaporizable components and heating the resulting composition to a temperature of at least 850 un. Concent 85% C is presented. (AEC)

  10. Lipid phosphate phosphatases regulate lysophosphatidic acid production and signaling in platelets: studies using chemical inhibitors of lipid phosphate phosphatase activity.

    PubMed

    Smyth, Susan S; Sciorra, Vicki A; Sigal, Yury J; Pamuklar, Zehra; Wang, Zuncai; Xu, Yong; Prestwich, Glenn D; Morris, Andrew J

    2003-10-31

    Blood platelets play an essential role in ischemic heart disease and stroke contributing to acute thrombotic events by release of potent inflammatory agents within the vasculature. Lysophosphatidic acid (LPA) is a bioactive lipid mediator produced by platelets and found in the blood and atherosclerotic plaques. LPA receptors on platelets, leukocytes, endothelial cells, and smooth muscle cells regulate growth, differentiation, survival, motility, and contractile activity. Definition of the opposing pathways of synthesis and degradation that control extracellular LPA levels is critical to understanding how LPA bioactivity is regulated. We show that intact platelets and platelet membranes actively dephosphorylate LPA and identify the major enzyme responsible as lipid phosphate phosphatase 1 (LPP1). Localization of LPP1 to the platelet surface is increased by exposure to LPA. A novel receptor-inactive sn-3-substituted difluoromethylenephosphonate analog of phosphatidic acid that is a potent competitive inhibitor of LPP1 activity potentiates platelet aggregation and shape change responses to LPA and amplifies LPA production by agonist-stimulated platelets. Our results identify LPP1 as a pivotal regulator of LPA signaling in the cardiovascular system. These findings are consistent with genetic and cell biological evidence implicating LPPs as negative regulators of lysophospholipid signaling and suggest that the mechanisms involve both attenuation of lysophospholipid actions at cell surface receptors and opposition of lysophospholipid production. PMID:12909631

  11. Immobilization of inorganic pyrophosphatase on nanodiamond particles retaining its high enzymatic activity.

    PubMed

    Rodina, Elena V; Valueva, Anastasiya V; Yakovlev, Ruslan Yu; Vorobyeva, Nataliya N; Kulakova, Inna I; Lisichkin, Georgy V; Leonidov, Nikolay B

    2015-01-01

    Nanodiamond (ND) particles are popular platforms for the immobilization of molecular species. In the present research, enzyme Escherichia coli inorganic pyrophosphatase (PPase) was immobilized on detonation ND through covalent or noncovalent bonding and its enzymatic activity was characterized. Factors affecting adsorption of PPase such as ND size and surface chemistry were studied. The obtained material is a submicron size association of ND particles and protein molecules in approximately equal amounts. Both covalently and noncovalently immobilized PPase retains a significant enzymatic activity (up to 95% of its soluble form) as well as thermostability. The obtained hybrid material has a very high enzyme loading capacity (∼1 mg mg(-1)) and may be considered as a promising delivery system of biologically active proteinaceous substances, particularly in the treatment of diseases such as calcium pyrophosphate crystal deposition disease and related pathologies. They can also be used as recoverable heterogeneous catalysts in the traditional uses of PPase. PMID:26489420

  12. Radionuclides, heavy metals and fluorine incidence at Tapira phosphate rocks, Brazil, and their industrial (by) products.

    PubMed

    da Conceição, Fabiano Tomazini; Bonotto, Daniel Marcos

    2006-01-01

    Inorganic phosphate fertilizers may contain radionuclides, heavy metals and fluorine. This paper presents the possible environmental hazards from Tapira phosphate rocks and their (by) products (Brazil) utilized as phosphate fertilizers. The activity concentration of 238U, 234U, 226Ra and 40K in Tapira phosphate rocks is within the world range for these rock types. The 232Th activity concentration is higher than the mean reported in phosphate rocks. A value of 2184 nGy h(-1) was obtained for the exposure dose rate in Tapira phosphate deposit area, which is indicative of a high background radiation area. The flotation-separation process causes the incorporation of no more than 9%, 11% and 24% of radionuclides, heavy metals and fluorine, respectively, into the phosphate concentrate. The radionuclides and heavy metals existing in phosphate fertilizers applied in Brazilian crops according to the recommended rates, do not raise their concentration in soils to harmful levels. PMID:16099562

  13. Spatial and Temporal Variability in the Concentration and Turnover of the Inorganic Phosphate and Adenosine-5'-triphosphate pools in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Björkman, Karin; Church, Matthew; Karl, David

    2015-04-01

    The microbial community's utilization of inorganic phosphate (Pi) and adenosine-5'-triphosphate (ATP) as a function of the Pi pool concentration was studied over a multi-year period at Station ALOHA (22.75˚N, 158˚W) in the North Pacific Subtropical Gyre (NPSG). Additionally, the spatial variability in these same properties was investigated along an east-west transect from California to Hawaii in the Fall of 2014. We used radiotracer techniques to determine the turnover times of the Pi or ATP pools respectively, and assessed the net production of dissolved organic phosphorus, and Pi hydrolysis rate from ATP. Pi concentrations in the upper water column at Station ALOHA are temporally highly dynamic, with periods of <10 nM-P to near 200 nM-P recorded within the top 50 m over the past decades of observations. During the California to Hawaii transect Pi concentrations showed a similarly large range (<10 to >200 nM-P), emphasizing the spatially and temporally mosaic nature of the upper ocean of this large biome. The Pi-pool turnover time ranged from a few hours to several weeks, and was strongly correlated with measured Pi pool concentrations (r2=0.8; n=30 Station ALOHA; n=15 transect). The calculated Pi uptake rates at Station ALOHA averaged 3.7±1.3 nM-P d-1 (n=30), reflecting the typically low maximum Pi uptake rates of the Prochlorococcus dominated community and the predominantly non-limiting Pi conditions. The Pi uptake rates along the transect were more variable than Station ALOHA (averaging 9.2±4.7 nM=P d-1, n=15), possibly due to a more diverse planktonic community structure, including stations with elevated concentrations of chlorophyll and primary productivity. The turnover time of the dissolved ATP pool was typically substantially shorter than for the Pi-pool (2-5 days at Station ALOHA; 0.3-2.5 days along the transect), likely reflecting its low nanomolar to picomolar ambient pool concentrations. However, at stations with the lowest SRP concentrations the

  14. TWEAK favors phosphate-induced calcification of vascular smooth muscle cells through canonical and non-canonical activation of NFκB

    PubMed Central

    Hénaut, L; Sanz, A B; Martin-Sanchez, D; Carrasco, S; Villa-Bellosta, R; Aldamiz-Echevarria, G; Massy, Z A; Sanchez-Nino, M D; Ortiz, A

    2016-01-01

    Vascular calcification (VC) is associated with increased cardiovascular mortality in aging, chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM) and atherosclerosis. TNF-like weak inducer of apoptosis (TWEAK) recently emerged as a new biomarker for the diagnosis and prognosis of cardiovascular diseases. TWEAK binding to its functional receptor Fn14 was reported to promote several steps of atherosclerotic plaque progression. However, no information is currently available on the role of TWEAK/Fn14 on the development of medial calcification, which is highly prevalent in aging, CKD and T2DM. This study explored the involvement of TWEAK in human vascular smooth muscle cells (h-VSMCs) calcification in vitro. We report that TWEAK binding to Fn14 promotes inorganic phosphate-induced h-VSMCs calcification, favors h-VSMCs osteogenic transition, decreasing acta2 and myh11 and increasing bmp2 mRNA and tissue non-specific alkaline phosphatase (TNAP), and increases MMP9 activity. Blockade of the canonical NFκB pathway reduced by 80% TWEAK pro-calcific properties and decreased osteogenic transition, TNAP and MMP9 activity. Blockade of non-canonical NFκB signaling by a siRNA targeting RelB reduced by 20% TWEAK pro-calcific effects and decreased TWEAK-induced loss of h-VSMCs contractile phenotype and MMP9 activity, without modulating bmp2 mRNA or TNAP activity. Inhibition of ERK1/2 activation by a MAPK kinase inhibitor did not influence TWEAK pro-calcific properties. Our results suggest that TWEAK/Fn14 directly favors inorganic phosphate-induced h-VSMCs calcification by activation of both canonical and non-canonical NFκB pathways. Given the availability of neutralizing anti-TWEAK strategies, our study sheds light on the TWEAK/Fn14 axis as a novel therapeutic target in the prevention of VC. PMID:27441657

  15. TWEAK favors phosphate-induced calcification of vascular smooth muscle cells through canonical and non-canonical activation of NFκB.

    PubMed

    Hénaut, L; Sanz, A B; Martin-Sanchez, D; Carrasco, S; Villa-Bellosta, R; Aldamiz-Echevarria, G; Massy, Z A; Sanchez-Nino, M D; Ortiz, A

    2016-01-01

    Vascular calcification (VC) is associated with increased cardiovascular mortality in aging, chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM) and atherosclerosis. TNF-like weak inducer of apoptosis (TWEAK) recently emerged as a new biomarker for the diagnosis and prognosis of cardiovascular diseases. TWEAK binding to its functional receptor Fn14 was reported to promote several steps of atherosclerotic plaque progression. However, no information is currently available on the role of TWEAK/Fn14 on the development of medial calcification, which is highly prevalent in aging, CKD and T2DM. This study explored the involvement of TWEAK in human vascular smooth muscle cells (h-VSMCs) calcification in vitro. We report that TWEAK binding to Fn14 promotes inorganic phosphate-induced h-VSMCs calcification, favors h-VSMCs osteogenic transition, decreasing acta2 and myh11 and increasing bmp2 mRNA and tissue non-specific alkaline phosphatase (TNAP), and increases MMP9 activity. Blockade of the canonical NFκB pathway reduced by 80% TWEAK pro-calcific properties and decreased osteogenic transition, TNAP and MMP9 activity. Blockade of non-canonical NFκB signaling by a siRNA targeting RelB reduced by 20% TWEAK pro-calcific effects and decreased TWEAK-induced loss of h-VSMCs contractile phenotype and MMP9 activity, without modulating bmp2 mRNA or TNAP activity. Inhibition of ERK1/2 activation by a MAPK kinase inhibitor did not influence TWEAK pro-calcific properties. Our results suggest that TWEAK/Fn14 directly favors inorganic phosphate-induced h-VSMCs calcification by activation of both canonical and non-canonical NFκB pathways. Given the availability of neutralizing anti-TWEAK strategies, our study sheds light on the TWEAK/Fn14 axis as a novel therapeutic target in the prevention of VC. PMID:27441657

  16. Combining phosphate and bacteria removal on chemically active filter membranes allows prolonged storage of drinking water.

    PubMed

    Rotzetter, A C C; Kellenberger, C R; Schumacher, C M; Mora, C; Grass, R N; Loepfe, M; Luechinger, N A; Stark, W J

    2013-11-13

    A chemically active filtration membrane with incorporated lanthanum oxide nanoparticles enables the removal of bacteria and phosphate at the same time and thus provides a simple device for preparation of drinking water and subsequent safe storage without using any kind of disinfectants. PMID:23913409

  17. Biochemical methods for quantifying sphingolipids: ceramide, sphingosine, sphingosine kinase-1 activity, and sphingosine-1-phosphate.

    PubMed

    Brizuela, Leyre; Cuvillier, Olivier

    2012-01-01

    Sphingolipids (ceramide, sphingosine, and sphingosine-1-phosphate) are bioactive lipids with important biological functions in proliferation, apoptosis, angiogenesis, and inflammation. Herein, we describe easy and rapid biochemical methods with the use of radiolabeled molecules ((3)H, (32)P) for their mass determination. Quantitation of sphingosine kinase-1 activity, the most studied isoform, is also included. PMID:22528435

  18. Measurement of the gain in a disk amplification stage with neodymium phosphate glass active elements

    SciTech Connect

    Voronich, Ivan N; Galakhov, I V; Garanin, Sergey G; Eroshenko, V A; Zaretskii, Aleksei I; Zimalin, B G; Ignat'ev, Ivan V; Kirdyashkin, M Yu; Kirillov, G A; Osin, Vladimir A; Rukavishnikov, N N; Sukharev, Stanislav A; Sharov, Oleg A; Charukhchev, Aleksandr V

    2003-06-30

    The measuring technique is described and time-resolved measurements of the small-signal gain as a function of the pump energy in a disk amplification stage with neodymium phosphate glass active elements in the 'Luch' facility are presented. The distribution of the gain over the amplifier aperture in the horizontal plane is measured. (lasers)

  19. Regulation of carbonic-anhydrase activity, inorganic-carbon uptake and photosynthetic biomass yield inChlamydomonas reinhardtii.

    PubMed

    Patel, B N; Merrett, M J

    1986-03-01

    The regulation of carbonic anhydrase by environmental conditions was determined forChlamydomonas reinhardtii. The depression of carbonic anhydrase in air-grown cells was pH-dependent. Growth of cells on air at acid pH, corresponding to 10 μm CO2 in solution, resulted in complete repression of carbonic-anhydrase activity. At pH 6.9, increasing the CO2 concentration to 0.15% (v/v) in the gas phase, corresponding to 11 μM in solution, was sufficient to completely repress carbonic-anhydrase activity. Photosynthesis and intracellular inorganic carbon were measured in air-grown and high-CO2-grown cells using a silicone-oil centrifugation technique. With carbonic anhydrase repressed cells limited inorganic-carbon accumulation resulted from non-specific binding of CO2. With air-grown cells, inorganic-carbon uptake at acid pH, i.e. 5.5, was linear up to 0.5 mM external inorganic-carbon concentration whereas at alkaline pH, i.e. 7.5, the accumulation ratio decreased with increase in external inorganic-carbon concentration. It is suggested that in air-grown cells at acid pH, CO2 is the inorganic carbon species that crosses the plasmalemma. The conversion of CO2 to HCO 3 (-) by carbonic anhydrase in the cytosol results in inorganic-carbon accumulation and maintains the diffusion gradient for carbon dioxide across the cell boundary. However, this mechanism will not account for energy-dependent accumulation of inorganic carbon when there is little difference in pH between the exterior and cytosol. PMID:24232432

  20. Controlling the release of active compounds from the inorganic carrier halloysite

    NASA Astrophysics Data System (ADS)

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-05-01

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  1. Controlling the release of active compounds from the inorganic carrier halloysite

    SciTech Connect

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-05-15

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  2. Biodegradable Inorganic Nanovector: Passive versus Active Tumor Targeting in siRNA Transportation.

    PubMed

    Park, Dae-Hwan; Cho, Jaeyong; Kwon, Oh-Joon; Yun, Chae-Ok; Choy, Jin-Ho

    2016-03-24

    The biodegradable inorganic nanovector based on a layered double hydroxide (LDH) holds great promise for gene and drug delivery systems. However, in vivo targeted delivery of genes through LDH still remains a key challenge in the development of RNA interference therapeutics. Here, we describe in vivo and in vitro delivery system for Survivin siRNA (siSurvivin) assembled with passive LDH with a particle size of 100 nm or active LDH conjugated with a cancer overexpressing receptor targeting ligand, folic acid (LDHFA), conferring them an ability to target the tumor by either EPR-based clathrin-mediated or folate receptor-mediated endocytosis. When not only transfected into KB cells but also injected into xenograft mice, LDHFA/siSurvivin induced potent gene silencing at mRNA and protein levels in vitro, and consequently achieved a 3.0-fold higher suppression of tumor volume than LDH/siSurvivin in vivo. This anti-tumor effect was attributed to a selectively 1.2-fold higher accumulation of siSurvivin in tumor tissue compared with other organs. Targeting to the tumor with inorganic nanovector can guide and accelerate an evolution of next-generation theranosis system. PMID:26879376

  3. Paraoxonase 1 activity in subchronic low-level inorganic arsenic exposure through drinking water.

    PubMed

    Afolabi, Olusegun K; Wusu, Adedoja D; Ogunrinola, Olufunmilayo O; Abam, Esther O; Babayemi, David O; Dosumu, Oluwatosin A; Onunkwor, Okechukwu B; Balogun, Elizabeth A; Odukoya, Olusegun O; Ademuyiwa, Oladipo

    2016-02-01

    Epidemiological evidences indicate close association between inorganic arsenic exposure via drinking water and cardiovascular diseases. While the exact mechanism of this arsenic-mediated increase in cardiovascular risk factors remains enigmatic, epidemiological studies indicate a role for paraoxonase 1 (PON1) in cardiovascular diseases. To investigate the association between inorganic arsenic exposure and cardiovascular diseases, rats were exposed to sodium arsenite (trivalent; 50, 100, and 150 ppm As) and sodium arsenate (pentavalent; 100, 150, and 200 ppm As) in their drinking water for 12 weeks. PON1 activity towards paraoxon (PONase) and phenylacetate (AREase) in plasma, lipoproteins, hepatic, and brain microsomal fractions were determined. Inhibition of PONase and AREase in plasma and HDL characterized the effects of the two arsenicals. While the trivalent arsenite inhibited PONase by 33% (plasma) and 46% (HDL), respectively, the pentavalent arsenate inhibited the enzyme by 41 and 34%, respectively. AREase activity was inhibited by 52 and 48% by arsenite, whereas the inhibition amounted to 72 and 67%, respectively by arsenate. The pattern of inhibition in plasma and HDL indicates that arsenite induced a dose-dependent inhibition of PONase whereas arsenate induced a dose-dependent inhibition of AREase. In the VLDL + LDL, arsenate inhibited PONase and AREase while arsenite inhibited PONase. In the hepatic and brain microsomal fractions, only the PONase enzyme was inhibited by the two arsenicals. The inhibition was more pronounced in the hepatic microsomes where a 70% inhibition was observed at the highest dose of pentavalent arsenic. Microsomal cholesterol was increased by the two arsenicals resulting in increased cholesterol/phospholipid ratios. Our findings indicate that decreased PON1 activity observed in arsenic exposure may be an incipient biochemical event in the cardiovascular effects of arsenic. Modulation of PON1 activity by arsenic may also be

  4. Glucose-6-phosphate mediates activation of the carbohydrate responsive binding protein (ChREBP)

    SciTech Connect

    Li, Ming V.; Chen, Weiqin; Harmancey, Romain N.; Nuotio-Antar, Alli M.; Imamura, Minako; Saha, Pradip; Taegtmeyer, Heinrich; Chan, Lawrence

    2010-05-07

    Carbohydrate response element binding protein (ChREBP) is a Mondo family transcription factor that activates a number of glycolytic and lipogenic genes in response to glucose stimulation. We have previously reported that high glucose can activate the transcriptional activity of ChREBP independent of the protein phosphatase 2A (PP2A)-mediated increase in nuclear entry and DNA binding. Here, we found that formation of glucose-6-phosphate (G-6-P) is essential for glucose activation of ChREBP. The glucose response of GAL4-ChREBP is attenuated by D-mannoheptulose, a potent hexokinase inhibitor, as well as over-expression of glucose-6-phosphatase (G6Pase); kinetics of activation of GAL4-ChREBP can be modified by exogenously expressed GCK. Further metabolism of G-6-P through the two major glucose metabolic pathways, glycolysis and pentose-phosphate pathway, is not required for activation of ChREBP; over-expression of glucose-6-phosphate dehydrogenase (G6PD) diminishes, whereas RNAi knockdown of the enzyme enhances, the glucose response of GAL4-ChREBP, respectively. Moreover, the glucose analogue 2-deoxyglucose (2-DG), which is phosphorylated by hexokinase, but not further metabolized, effectively upregulates the transcription activity of ChREBP. In addition, over-expression of phosphofructokinase (PFK) 1 and 2, synergistically diminishes the glucose response of GAL4-ChREBP. These multiple lines of evidence support the conclusion that G-6-P mediates the activation of ChREBP.

  5. Alkaline Phosphatase Activity : an overlooked player on the phosphate behavior in macrotidal estuaries

    NASA Astrophysics Data System (ADS)

    Delmas, Daniel; Labry, Claire; Youenou, Agnes; Quere, Julien; Auguet, Jean Christophe; Montanie, Helene

    2014-05-01

    The non-conservative behavior of phosphate within the estuarine salinity gradient is essentially assigned to physico-chemical processes, such as desorption at low salinity and to benthic exchanges. Microbial phosphatase activity (APA), generally related to phosphate deficiency, is seldom studied in phosphate rich estuarine waters. In order to address the impact of microbial activity (bacterial abundance, production BSP, APA) on phosphate behavior, we studied these activities on a seasonal basis within the salinity gradient of two macrotidal estuaries presenting different levels of suspended solids. Whatever the season the Charente estuary is characterized by high levels of Suspended Particulate Matter (SPM > 1g.L-1), particularly in the Maximum Turbidity Zone (MTZ) located at the 5-10 psu. In this area characterized by high BSP and APA there is a significant increase of PO4 levels especially during summer. In the Aulne estuary the particle load is significantly lower (1/10) but high BSP and APA are equally recorded. In the highly turbid waters of the Charente estuary, active phytoplankton is virtually absent as pheopigments constitute up to 80% of the total pigments, particularly in the MTZ, therefore APA may essentially have a bacterial origin. In the Aulne estuary attached bacteria are dominant, both in numbers and production, and their distribution along the haline gradient perfectly follows those of APA and phosphate levels. These observations, associated with the very close relationships observed between APA, SPM and BSP, suggest that APA derive mainly from bacterial (attached) origin and operate at the expense of particulate phosphorus and hence contribute to PO4 regeneration, especially in spring and summer. Finally, as APA increased as PO4, whereas the reverse is observed in both fresh and marine waters, an original scheme for APA regulation, related to the large dominance of attached bacteria can be described for the estuarine waters.

  6. Archaeal Inorganic Pyrophosphatase Displays Robust Activity under High-Salt Conditions and in Organic Solvents

    PubMed Central

    McMillan, Lana J.; Hepowit, Nathaniel L.

    2015-01-01

    Soluble inorganic pyrophosphatases (PPAs) that hydrolyze inorganic pyrophosphate (PPi) to orthophosphate (Pi) are commonly used to accelerate and detect biosynthetic reactions that generate PPi as a by-product. Current PPAs are inactivated by high salt concentrations and organic solvents, which limits the extent of their use. Here we report a class A type PPA of the haloarchaeon Haloferax volcanii (HvPPA) that is thermostable and displays robust PPi-hydrolyzing activity under conditions of 25% (vol/vol) organic solvent and salt concentrations from 25 mM to 3 M. HvPPA was purified to homogeneity as a homohexamer by a rapid two-step method and was found to display non-Michaelis-Menten kinetics with a Vmax of 465 U · mg−1 for PPi hydrolysis (optimal at 42°C and pH 8.5) and Hill coefficients that indicated cooperative binding to PPi and Mg2+. Similarly to other class A type PPAs, HvPPA was inhibited by sodium fluoride; however, hierarchical clustering and three-dimensional (3D) homology modeling revealed HvPPA to be distinct in structure from characterized PPAs. In particular, HvPPA was highly negative in surface charge, which explained its extreme resistance to organic solvents. To demonstrate that HvPPA could drive thermodynamically unfavorable reactions to completion under conditions of reduced water activity, a novel coupled assay was developed; HvPPA hydrolyzed the PPi by-product generated in 2 M NaCl by UbaA (a “salt-loving” noncanonical E1 enzyme that adenylates ubiquitin-like proteins in the presence of ATP). Overall, we demonstrate HvPPA to be useful for hydrolyzing PPi under conditions of reduced water activity that are a hurdle to current PPA-based technologies. PMID:26546423

  7. Properties of Ce-activated alkali-lutetium double phosphate scintillators

    SciTech Connect

    Wiśniewski, D.; Wojtowicz, A. J.; Boatner, Lynn A

    2010-01-01

    The scintillation properties of Ce-activated alkali-lutetium double phosphate single crystals that vary with the alkali ion type and activation level are summarized and compared. The materials investigated here have been identified as fast and efficient scintillators for the detection of x-ray and radiation, and in case of Li3Lu(PO4)2:Ce, for thermal neutron detection as well.

  8. Determination of phosphate in natural waters by activation analysis of tungstophosphoric acid

    USGS Publications Warehouse

    Allen, Herbert E.; Hahn, Richard B.

    1969-01-01

    Activation analysis may be used to determine quantitatively traces of phosphate in natural waters. Methods based on the reaction 31P(n,γ)32P are subject to interference by sulfur and chlorine which give rise to 32P through n,p and n,α reactions. If the ratio of phosphorus to sulfur or chlorine is small, as it is in most natural waters, accurate analyses by these methods are difficult to achieve. In the activation analysis method, molybdate and tungstate ions are added to samples containing phosphate ion to form tungstomolybdophosphoric acid. The complex is extracted with 2,6-dimethyl-4-heptanone. After activation of an aliquot of the organic phase for 1 hour at a flux of 1013 neutrons per cm2, per second, the gamma spectrum is essentially that of tungsten-187. The induced activity is proportional to the concentration of phosphate in the sample. A test of the method showed it to give accurate results at concentrations of 4 to at least 200 p.p.b. of phosphorus when an aliquot of 100 μl. was activated. By suitable reagent purification, counting for longer times, and activation of larger aliquots, the detection limit could be lowered several hundredfold.

  9. Spatial and decadal variations in inorganic nitrogen wet deposition in China induced by human activity

    PubMed Central

    Jia, Yanlong; Yu, Guirui; He, Nianpeng; Zhan, Xiaoyun; Fang, Huajun; Sheng, Wenping; Zuo, Yao; Zhang, Dayong; Wang, Qiufeng

    2014-01-01

    Atmospheric nitrogen (N) deposition, an important component in the global N cycle, has increased sharply in recent decades in China. Here, we constructed national-scale inorganic N wet deposition (Ndep) patterns in China based on data from 280 observational sites and analysed the effects of anthropogenic sources and precipitation on Ndep. Our results showed that the mean Ndep over China increased approximately 25%, from 11.11 kg ha−1 a−1 in the 1990s to 13.87 in the 2000s. Ndep was highest over southern China and exhibited a decreasing gradient from southern to western and northern China. The decadal difference in Ndep between the 1990s and 2000s was primarily caused by increases in energy consumption and N fertiliser use. Our findings conformed that anthropogenic activities were the main reason for the Ndep increase and provide a scientific background for studies on ecological effects of N deposition in China. PMID:24441731

  10. Levels of Phosphate Esters in Spirodela

    PubMed Central

    Bieleski, R. L.

    1968-01-01

    The duckweed Spirodela oligorrhiza was grown in sterile nutrient solutions that contained 1 mm phosphate-32P at various specific activities. In solutions with activities higher than 2 μc per μmole per ml, plant growth was inhibited after a time, and the physical appearance of the plants was affected. The critical level of radiation, at which growth was first affected, corresponded to 5 kilorads. Plants were grown for 9 days (5 generations) in a culture solution containing phosphate at 0.5 μc per μmole per ml (radiation load approx 0.5 kilorads) so that all phosphorus-containing materials in the tissue became uniformly labeled. The various radioactive compounds were extracted, chromatographed, identified, and their radioactivity was measured. From this radioactivity plus the specific activity of the supplied phosphate, the amount of each compound was calculated. The data constitute a complete balance-sheet for phosphorus in a plant tissue. The identity of 98% of the phosphorus in the tissue was determined. Inorganic phosphate (32,700 mμmoles/g fr wt) was the predominant phosphorus-containing compound; RNA (5100 mμmoles P/g fr wt) was the main organic phosphate; phosphatidyl choline (1600 mμmoles/g fr wt) was the main phospholipid, and glucose-6-phosphate (500 mμmoles/g fr wt) the main acid-soluble phosphate ester. Amounts of other phosphorus compounds are given. Images PMID:16656910

  11. Inorganic polyphosphate is a potent activator of the mitochondrial permeability transition pore in cardiac myocytes

    PubMed Central

    Seidlmayer, Lea K.; Gomez-Garcia, Maria R.; Blatter, Lothar A.; Pavlov, Evgeny

    2012-01-01

    Mitochondrial dysfunction caused by excessive Ca2+ accumulation is a major contributor to cardiac cell and tissue damage during myocardial infarction and ischemia–reperfusion injury (IRI). At the molecular level, mitochondrial dysfunction is induced by Ca2+-dependent opening of the mitochondrial permeability transition pore (mPTP) in the inner mitochondrial membrane, which leads to the dissipation of mitochondrial membrane potential (ΔΨm), disruption of adenosine triphosphate production, and ultimately cell death. Although the role of Ca2+ for induction of mPTP opening is established, the exact molecular mechanism of this process is not understood. The aim of the present study was to test the hypothesis that the adverse effect of mitochondrial Ca2+ accumulation is mediated by its interaction with inorganic polyphosphate (polyP), a polymer of orthophosphates linked by phosphoanhydride bonds. We found that cardiac mitochondria contained significant amounts (280 ± 60 pmol/mg of protein) of short-chain polyP with an average length of 25 orthophosphates. To test the role of polyP for mPTP activity, we investigated kinetics of Ca2+ uptake and release, ΔΨm and Ca2+-induced mPTP opening in polyP-depleted mitochondria. polyP depletion was achieved by mitochondria-targeted expression of a polyP-hydrolyzing enzyme. Depletion of polyP in mitochondria of rabbit ventricular myocytes led to significant inhibition of mPTP opening without affecting mitochondrial Ca2+ concentration by itself. This effect was observed when mitochondrial Ca2+ uptake was stimulated by increasing cytosolic [Ca2+] in permeabilized myocytes mimicking mitochondrial Ca2+ overload observed during IRI. Our findings suggest that inorganic polyP is a previously unrecognized major activator of mPTP. We propose that the adverse effect of polyphosphate might be caused by its ability to form stable complexes with Ca2+ and directly contribute to inner mitochondrial membrane permeabilization. PMID:22547663

  12. Regulation by sphingosine 1-phosphate of Bax and Bad activities during apoptosis in a MEK-dependent manner.

    PubMed

    Betito, Susan; Cuvillier, Olivier

    2006-02-24

    Herein we report that the prosurvival sphingolipid sphingosine 1-phosphate regulates the activities of both Bad and Bax during apoptosis of Jurkat cells. First, sphingosine 1-phosphate treatment results in Bad inactivation via the ERK/Rsk-1 pathway. Second, sphingosine 1-phosphate blocks the translocation of Bax to the mitochondria induced by Fas ligation. MEK inhibition by PD98059 or U0126 not only abrogates sphingosine 1-phosphate-induced Bad phosphorylation, but also its cytoprotective effect. Furthermore, inhibition of both mitochondrial cytochrome c efflux and Bax translocation to the mitochondria by sphingosine 1-phosphate could be overcome by PD98059 or U0126. Hence, the MEK/ERK pathway seems to be crucial for the survival effects initiated by sphingosine 1-phosphate. PMID:16414356

  13. Microbial activities and phosphorus cycling: An application of oxygen isotope ratios in phosphate

    NASA Astrophysics Data System (ADS)

    Stout, Lisa M.; Joshi, Sunendra R.; Kana, Todd M.; Jaisi, Deb P.

    2014-08-01

    Microorganisms carry out biochemical transformations of nutrients that make up their cells. Therefore, understanding how these nutrients are transformed or cycled in natural environments requires knowledge of microbial activity. Commonly used indicators for microbial activity typically include determining microbial respiration by O2/CO2 measurements, cell counts, and measurement of enzyme activities. However, coupled studies on nutrient cycling and microbial activity are not given enough emphasis. Here we apply phosphate oxygen isotope ratios (δ18OP) as a tool for measurement of microbial activity and compare the rate of isotope exchange with methods of measuring microbial activities that are more commonly applied in environmental studies including respiration, dehydrogenase activity, alkaline phosphatase activity, and cell counts. Our results show that different bacteria may have different strategies for P uptake, storage and release, their respiration and consequently expression of DHA and APase activities, but in general the trend of their enzyme activities are comparable. Phosphate δ18OP values correlated well with these other parameters used to measure microbial activity with the strongest linear relationships between δ18OP and CO2 evolution (r = -0.99). Even though the rate of isotope exchange for each microorganism used in this study is different, the rate per unit CO2 respiration showed one general trend, where δ18OP values move towards equilibrium while CO2 is generated. While this suggests that P cycling among microorganisms used in this study can be generalized, further research is needed to determine whether the microorganism-specific isotope exchange trend may occur in natural environments. In summary, phosphate oxygen isotope measurements may offer an alternative for use as a tracer to measure microbial activity in soils, sediments, and many other natural environments.

  14. 77 FR 5061 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Inorganic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ..., see the related notice published in the Federal Register on October 20, 2011 (76 FR 65217). Interested...; Inorganic Arsenic Standard ACTION: Notice. SUMMARY: The Department of Labor (DOL) is submitting the..., ``Inorganic Arsenic Standard,'' to the Office of Management and Budget (OMB) for review and approval...

  15. Effects of inorganic carbon limitation on anaerobic ammonium oxidation (anammox) activity.

    PubMed

    Kimura, Yuya; Isaka, Kazuichi; Kazama, Futaba

    2011-03-01

    Anammox bacteria are chemoautotrophic bacteria that oxidize ammonium with nitrite as the electron acceptor and with CO(2) as the main carbon source. The effects of inorganic carbon (IC) limitation on anammox bacteria were investigated using continuous feeding tests. In this study, a gel carrier with entrapped anammox sludge was used. It was clearly shown that the anammox activity deteriorated with a decrease in the influent IC concentration. The relationship between the influent IC concentration and the anammox activity was analyzed using Michaelis-Menten kinetics, and the apparent K(m) was determined to be 1.2mg-C/L. The activity could be recovered by adding IC to the influent. The consumption ratio of IC to ammonium was not constant and mainly depended on the influent ratio of the IC to ammonium concentrations (inf.IC/inf.NH(4)-N). The results indicated that an inf.IC/inf.NH(4)-N ratio of 0.2 in the anammox reactor was ideal for the anammox process using gel cubes. PMID:21256745

  16. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance

    NASA Astrophysics Data System (ADS)

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-01

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm-2 at the current density of 6 mA cm-2 in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (~15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ~88% of the capacitance when the charging rate increased from 6 to 48 mA cm-2. Moreover, the activated CC electrode exhibited excellent cycling stability with ~97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm-2. A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors.Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as

  17. Reproducible quantification of osteoclastic activity: characterization of a biomimetic calcium phosphate assay.

    PubMed

    Maria, Salwa M; Prukner, Christiane; Sheikh, Zeeshan; Mueller, Frank; Barralet, Jake E; Komarova, Svetlana V

    2014-07-01

    Osteoclasts are responsible for bone and joint destruction in rheumatoid arthritis, periodontitis, and osteoporosis. Animal tusk slice assays are standard for evaluating the effect of therapeutics on these cells. However, in addition to batch-to-batch variability inherent to animal tusks, their use is clearly not sustainable. Our objective was to develop and characterize a biomimetic calcium phosphate assay based on the use of phase pure hydroxyapatite coated as a thin film on the surface of culture plates, to facilitate the reproducible quantification of osteoclast resorptive activity. Osteoclasts were formed from RAW 264.7 mouse monocyte cell line using a pro-resorptive cytokine RANKL (50 ng/mL). No change in substrate appearance was noted after culture with media without cells, or undifferentiated monocytes. Only in the presence of osteoclasts localized areas of calcium phosphate dissolution were observed. The total area resorbed positively correlated with the osteoclast numbers (R(2) = 0.99). The resorbed area was significantly increased by the addition of RANKL, and decreased after application of known inhibitors of osteoclast resorptive activity, calcitonin (10 μM), or alendronate (100 μM). Thus, calcium phosphate coated substrates allow reliable monitoring of osteoclast resorptive activity and offer an alternative to animal tusk slice assays. PMID:24259122

  18. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance.

    PubMed

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-21

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm(-2) at the current density of 6 mA cm(-2) in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (∼15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ∼88% of the capacitance when the charging rate increased from 6 to 48 mA cm(-2). Moreover, the activated CC electrode exhibited excellent cycling stability with ∼97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm(-2). A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors. PMID:27141910

  19. Glucose-6-phosphate mediates activation of the carbohydrate responsive binding protein (ChREBP)

    PubMed Central

    Li, Ming V.; Chen, Weiqin; Harmancey, Romain N; Nuotio-Antar, Alli M.; Imamura, Minako; Saha, Pradip; Taegtmeyer, Heinrich; Chan, Lawrence

    2010-01-01

    Carbohydrate Response Element Binding Protein (ChREBP) is a Mondo family transcription factor that activates a number of glycolytic and lipogenic genes in response to glucose stimulation. We have previously reported that high glucose can activate the transcriptional activity of ChREBP independent of the protein phosphatase 2A (PP2A)-mediated increase in nuclear entry and DNA binding. Here we found that formation of glucose-6-phosphate (G-6-P) is essential for glucose activation of ChREBP. The glucose response of GAL4-ChREBP is attenuated by D-mannoheptulose, a potent hexokinase inhibitor, as well as over-expression of glucose-6-phosphatase (G6Pase); kinetics of activation of GAL4-ChREBP can be modified by exogenously expressed GCK. Further metabolism of G-6-P through the two major glucose metabolic pathways, glycolysis and pentose phosphate pathway, is not required for activation of ChREBP; over-expression of glucose-6-phosphate dehydrogenase (G6PD) diminishes, whereas RNAi knockdown of the enzyme enhances, the glucose response of GAL4-ChREBP, respectively. Moreover, the glucose analogue 2-deoxyglucose (2-DG), which is phosphorylated by hexokinase, but not further metabolized, effectively upregulates the transcription activity of ChREBP. In addition, over-expression of phosphofructokinase (PFK) 1 and 2, synergistically diminishes the glucose response of GAL4-ChREBP. These multiple lines of evidence support the conclusion that G-6-P mediates the activation of ChREBP. PMID:20382127

  20. Structure of inorganic pyrophosphatase from Staphylococcus aureus reveals conformational flexibility of the active site.

    PubMed

    Gajadeera, Chathurada S; Zhang, Xinyi; Wei, Yinan; Tsodikov, Oleg V

    2015-02-01

    Cytoplasmic inorganic pyrophosphatase (PPiase) is an enzyme essential for survival of organisms, from bacteria to human. PPiases are divided into two structurally distinct families: family I PPiases are Mg(2+)-dependent and present in most archaea, eukaryotes and prokaryotes, whereas the relatively less understood family II PPiases are Mn(2+)-dependent and present only in some archaea, bacteria and primitive eukaryotes. Staphylococcus aureus (SA), a dangerous pathogen and a frequent cause of hospital infections, contains a family II PPiase (PpaC), which is an attractive potential target for development of novel antibacterial agents. We determined a crystal structure of SA PpaC in complex with catalytic Mn(2+) at 2.1Å resolution. The active site contains two catalytic Mn(2+) binding sites, each half-occupied, reconciling the previously observed 1:1 Mn(2+):enzyme stoichiometry with the presence of two divalent metal ion sites in the apo-enzyme. Unexpectedly, despite the absence of the substrate or products in the active site, the two domains of SA PpaC form a closed active site, a conformation observed in structures of other family II PPiases only in complex with substrate or product mimics. A region spanning residues 295-298, which contains a conserved substrate binding RKK motif, is flipped out of the active site, an unprecedented conformation for a PPiase. Because the mutant of Arg295 to an alanine is devoid of activity, this loop likely undergoes an induced-fit conformational change upon substrate binding and product dissociation. This closed conformation of SA PPiase may serve as an attractive target for rational design of inhibitors of this enzyme. PMID:25576794

  1. Activation and splitting of carbon dioxide on the surface of an inorganic electride material

    PubMed Central

    Toda, Yoshitake; Hirayama, Hiroyuki; Kuganathan, Navaratnarajah; Torrisi, Antonio; Sushko, Peter V.; Hosono, Hideo

    2013-01-01

    Activation of carbon dioxide is the most important step in its conversion into valuable chemicals. Surfaces of stable oxide with a low work function may be promising for this purpose. Here we report that the surfaces of the inorganic electride [Ca24Al28O64]4+(e−)4 activate and split carbon dioxide at room temperature. This behaviour is attributed to a high concentration of localized electrons in the near-surface region and a corrugation of the surface that can trap oxygen atoms and strained carbon monoxide and carbon dioxide molecules. The [Ca24Al28O64]4+(e−)4 surface exposed to carbon dioxide is studied using temperature-programmed desorption, and spectroscopic methods. The results of these measurements, corroborated with ab initio simulations, show that both carbon monoxide and carbon dioxide adsorb on the [Ca24Al28O64]4+(e−)4 surface at RT and above and adopt unusual configurations that result in desorption of molecular carbon monoxide and atomic oxygen upon heating. PMID:23986101

  2. Enhancing the adsorption of ionic liquids onto activated carbon by the addition of inorganic salts

    PubMed Central

    Neves, Catarina M. S. S.; Lemus, Jesús; Freire, Mara G.; Palomar, Jose; Coutinho, João A. P.

    2014-01-01

    Most ionic liquids (ILs) are either water soluble or present a non-negligible miscibility with water that may cause some harmful effects upon their release into the environment. Among other methods, adsorption of ILs onto activated carbon (AC) has shown to be an effective technique to remove these compounds from aqueous solutions. However, this method has proved to be viable only for hydrophobic ILs rather than for the hydrophilic that, being water soluble, have a larger tendency for contamination. In this context, an alternative approach using the salting-out ability of inorganic salts is here proposed to enhance the adsorption of hydrophilic ILs onto activated carbon. The effect of the concentrations of Na2SO4 on the adsorption of five ILs onto AC was investigated. A wide range of ILs that allow the inspection of the IL cation family (imidazolium- and pyridinium-based) and the anion nature (accounting for its hydrophilicity and fluorination) through the adsorption onto AC was studied. In general, it is shown that the use of Na2SO4 enhances the adsorption of ILs onto AC. In particular, this effect is highly relevant when dealing with hydrophilic ILs that are those that are actually poorly removed by AC. In addition, the COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used aiming at complementing the experimental data obtained. This work contributes with the development of novel methods to remove ILs from water streams aiming at creating “greener” processes. PMID:25516713

  3. Photoluminescence Mechanism and Photocatalytic Activity of Organic-Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration.

    PubMed

    Akyildiz, Halil I; Stano, Kelly L; Roberts, Adam T; Everitt, Henry O; Jur, Jesse S

    2016-05-01

    Organic-inorganic hybrid materials formed by sequential vapor infiltration (SVI) of trimethylaluminum into polyester fibers are demonstrated, and the photoluminescence of the fibers is evaluated using a combined UV-vis and photoluminescence excitation (PLE) spectroscopy approach. The optical activity of the modified fibers depends on infiltration thermal processing conditions and is attributed to the reaction mechanisms taking place at different temperatures. At low temperatures a single excitation band and dual emission bands are observed, while, at high temperatures, two distinct absorption bands and one emission band are observed, suggesting that the physical and chemical structure of the resulting hybrid material depends on the SVI temperature. Along with enhancing the photoluminescence intensity of the PET fibers, the internal quantum efficiency also increased to 5-fold from ∼4-5% to ∼24%. SVI processing also improved the photocatalytic activity of the fibers, as demonstrated by photodeposition of Ag and Au metal particles out of an aqueous metal salt solution onto fiber surfaces via UVA light exposure. Toward applications in flexible electronics, well-defined patterning of the metallic materials is achieved by using light masking and focused laser rastering approaches. PMID:27063955

  4. Mn0.95I0.02[PO3(OH)] · 2H2O phosphate-iodate, an inorganic analogue of phosphonates

    NASA Astrophysics Data System (ADS)

    Belokoneva, E. L.; Dimitrova, O. V.; Volkov, A. S.

    2015-09-01

    The new Mn0.95I0.02[PO3(OH)] · 2H2O phosphate-iodate (space group Pnam = Pnma, D {2/h 16}) is obtained under hydrothermal conditions. The crystal structure is determined without preliminary knowledge of the chemical formula. The structure consists of layers of MnО6 octahedra connected with PO4 tetrahedra. Water molecules are located between the layers. [IO3]- groups having a typical umbrella-like coordination are statistically implanted in layers of MnО6 octahedra at a distance of 1.2 Å from Mn atoms. Their content in the crystal is minor. The structures of the phosphate-iodate coincides with the structures of phosphonates with consideration for the replacement of one (OH) vertex of the РО4 tetrahedron by the organic methyl radical СН3. In the structures of phosphonates and earlier studied phosphates, identical layers are distinguished and the cause of the existence of two MDO varieties is established based on the analysis within the OD theory. Possible hybrid structures derived from the prototypes under consideration are predicted.

  5. Control of 5-aminolaevulinate synthetase activity in Rhodopseudomonas spheroides. Binding of pyridoxal phosphate to 5-aminolaevulinate synthetase.

    PubMed Central

    Davies, R C; Neuberger, A

    1979-01-01

    1. Pyridoxal 5'-phosphate is a cofactor essential for the enzymic activity of aminolaevulinate synthetase from Rhodopseudomonas spheroides. It also aids activation of the low-activity enzyme by trisulphides such as cystine trisulphide, whereas inactivation of enzyme is facilitated by its absence. 2. The fluorescence spectrum of purified high-activity enzyme is that expected for a pyridoxal phosphate--Schiff base, but the firmly bound cofactor does not appear to be at the active centre. In dilute solutions of enzyme this grouping is inaccessible to nucleophiles such as glycine, hydroxylamine, borohydride and cyanide, at pH 7.4. 3. An active-centre Schiff base is formed between enzyne and added pyridoxal phosphate, which is accessible to nucleophiles. Concentrated solutions of this enzyme--Schiff base on treatment with glycine yield apo- and semi-apoenzyme, which can re-bind pyridoxal phosphate. 4. Two types of binding of pyridoxal phosphate are distinguishable in dilute solution of enzyme, but these become indistinguishable when concentrated solutions are treated with cofactor. A change occurs in the susceptibility towards borohydride of the fluorescence of the "structural" pyridoxal phosphate. 5. One or two molecules of cofactor are bound per subunit of mol. wt. 50 000 in semiapo- or holo-enzyme. The fluorescence of pyridoxamine phosphate covalently bound to enzyme also indicates one to two nmol of reducible Schiff base per 7000 units of activity in purified and partially purified samples of enzyme. 6. Cyanide does not convert high-activity into low-activity enzyme, but with the enzyme-pyridoxal phosphate complex it forms a yellow fluorescent derivative that is enzymically active. PMID:312102

  6. Continuous cellularization of calcium phosphate hybrid scaffolds induced by plasma polymer activation.

    PubMed

    Bergemann, Claudia; Cornelsen, Matthias; Quade, Antje; Laube, Thorsten; Schnabelrauch, Matthias; Rebl, Henrike; Weißmann, Volker; Seitz, Hermann; Nebe, Barbara

    2016-02-01

    The generation of hybrid materials based on β-tricalcium phosphate (TCP) and various biodegradable polymers like poly(l-lactide-co-d,l-lactide) (PLA) represents a common approach to overcoming the disadvantages of pure TCP devices. These disadvantages lie in TCP's mechanical properties, such as brittleness. The positive characteristic of PLA - improvement of compressive strength of calcium phosphate scaffolds - is diametrically opposed to its cell attractiveness. Therefore, the objective of this work was to optimize osteoblast migration and cellularization inside a three-dimensionally (3D) printed, PLA polymer stabilized TCP hybrid scaffold by a plasma polymer process depositing amino groups via allylamine. MG-63 osteoblastic cells inside the 10mm hybrid scaffold were dynamically cultivated for 14days in a 3D model system integrated in a perfusion reactor. The whole TCP/PLA hybrid scaffold was continuously colonized due to plasma polymerized allylamine activation inducing the migration potential of osteoblasts. PMID:26652403

  7. MESOPOROUS IRON PHOSPHATE AS AN ACTIVE, SELECTIVE AND RECYCLABLE CATALYST FOR THE SYNTHESIS OF NOPOL BY PRINS CONDENSATION

    EPA Science Inventory


    Mesoporous iron phosphate is found to be a highly active and recyclable heterogeneous catalyst for the selective synthesis of nopol by Prins condensation of ?-pinene and paraformaldehyde in acetonitrile at 80 oC.



  8. Enzymatically synthesized inorganic polymers as morphogenetically active bone scaffolds: application in regenerative medicine.

    PubMed

    Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G

    2014-01-01

    In recent years a paradigm shift in understanding of human bone formation has occurred that starts to change current concepts in tissue engineering of bone and cartilage. New discoveries revealed that fundamental steps in biomineralization are enzyme driven, not only during hydroxyapatite deposition, but also during initial bioseed formation, involving the transient deposition and subsequent transformation of calcium carbonate to calcium phosphate mineral. The principal enzymes mediating these reactions, carbonic anhydrase and alkaline phosphatase, open novel targets for pharmacological intervention of bone diseases like osteoporosis, by applying compounds acting as potential activators of these enzymes. It is expected that these new findings will give an innovation boost for the development of scaffolds for bone repair and reconstruction, which began with the use of bioinert materials, followed by bioactive materials and now leading to functional regenerative tissue units. These new developments have become possible with the discovery of the morphogenic activity of bioinorganic polymers, biocalcit, bio-polyphosphate and biosilica that are formed by a biogenic, enzymatic mechanism, a driving force along with the development of novel rapid-prototyping three-dimensional (3D) printing methods and bioprinting (3D cell printing) techniques that may allow a fabrication of customized implants for patients suffering in bone diseases in the future. PMID:25376489

  9. Substrate kinetics of the tonoplast h-translocating inorganic pyrophosphatase and its activation by free mg.

    PubMed

    White, P J; Marshall, J; Smith, J A

    1990-07-01

    To clarify the kinetic characteristics and ionic requirements of the tonoplast H(+)-translocating inorganic pyrophosphatase (H(+)-PPiase), PPi hydrolysis and PPi-dependent H(+) transport were studied in tonoplast vesicles isolated from leaf mesophyll tissue of Kalanchoë daigremontiana Hamet et Perrier de la Bâthie. The tonoplast H(+)-PPiase showed an absolute requirement for a monovalent cation and exhibited hyperbolic kinetics with respect to cation concentration. H(+)-PPiase activity was maximal in the presence of K(+) (K(50) approximately 3 millimolar), with PPi-dependent H(+) transport being more selective for K(+) than PPi hydrolysis. When assayed in the presence of 50 millimolar KCl at fixed PPi concentrations, H(+)-PPiase activity showed sigmoidal kinetics with respect to total Mg concentration, reflecting a requirement for a Mg/PPi complex as substrate and free Mg(2+) for activation. At saturating concentrations of free Mg(2+), H(+)-PPiase activity exhibited Michaelis-Menten kinetics towards MgPPi(2-) but not Mg(2)PPi, demonstrating that MgPPi(2-) was the true substrate of the enzyme. The apparent K(m) (MgPPi(2-)) for PPi hydrolysis (17 micromolar) was significantly higher than that for PPi-dependent H(+) transport (7 micromolar). Free Mg(2+) was shown to be an allosteric activator of the H(+)-PPiase, with Hill coefficients of 2.5 for PPi hydrolysis and 2.7 for PPi-dependent H(+) transport. Half-maximal H(+)-PPiase activity occurred at a free Mg(2+) concentration of 1.1 millimolar, which lies within the range of accepted values for cytosolic Mg(2+). In contrast, cytosolic concentrations of K(+) and MgPPi(2-) appear to be saturating for H(+)-PPiase activity. We propose that one function of the H(+)-PPiase may be to act as an ancillary enzyme that maintains the proton-motive force across the vacuolar membrane when the activity of the tonoplast H(+)-ATPase is restricted by substrate availability. As ATP levels decline in the cytosol, free Mg(2+) would be

  10. The utilization of fructose by Escherichia coli. Properties of a mutant defective in fructose 1-phosphate kinase activity.

    PubMed

    Ferenci, T; Kornberg, H L

    1973-02-01

    1. The isolation and properties of a mutant of Escherichia coli devoid of fructose 1-phosphate kinase activity are described. 2. This mutant grew in media containing any one of a variety of substances, including hexoses, hexose 6-phosphates, sugar acids and glucogenic substrates, at rates not significantly different from those at which the parent organism grew on these substrates. However, only the parent grew on fructose or fructose 1-phosphate. 3. Fructose and fructose 1-phosphate inhibit the growth of the mutant, but not of its parent, on other carbon sources. 4. Even though not previously exposed to fructose, the mutant took up [(14)C]fructose rapidly but to only a small extent: [(14)C]fructose 1-phosphate was identified as the predominant labelled product. In contrast, the equally rapid but more extensive uptake of [(14)C]fructose by the parent organism required prior growth in the presence of fructose. PMID:4579702

  11. Trivalent metal ions based on inorganic compounds with in vitro inhibitory activity of matrix metalloproteinase 13.

    PubMed

    Wen, Hanyu; Qin, Yuan; Zhong, Weilong; Li, Cong; Liu, Xiang; Shen, Yehua

    2016-10-01

    Collagenase-3 (MMP-13) inhibitors have attracted considerable attention in recent years and have been developed as a therapeutic target for a variety of diseases, including cancer. Matrix metalloproteinases (MMPs) can be inhibited by a multitude of compounds, including hydroxamic acids. Studies have shown that materials and compounds containing trivalent metal ions, particularly potassium hexacyanoferrate (III) (K3[Fe(CN)6]), exhibit cdMMP-13 inhibitory potential with a half maximal inhibitory concentration (IC50) of 1.3μM. The target protein was obtained by refolding the recombinant histidine-tagged cdMMP-13 using size exclusion chromatography (SEC). The secondary structures of the refolded cdMMP-13 with or without metal ions were further analyzed via circular dichroism and the results indicate that upon binding with metal ions, an altered structure with increased domain stability was obtained. Furthermore, isothermal titration calorimetry (ITC) experiments demonstrated that K3[Fe(CN)6]is able to bind to MMP-13 and endothelial cell tube formation tests provide further evidence for this interaction to exhibit anti-angiogenesis potential. To the best of our knowledge, no previous report of an inorganic compound featuring a MMP-13 inhibitory activity has ever been reported in the literature. Our results demonstrate that K3[Fe(CN)6] is useful as a new effective and specific inhibitor for cdMMP-13 which may be of great potential for future drug screening applications. PMID:27542739

  12. The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and Aspergillus niger phytase

    NASA Astrophysics Data System (ADS)

    von Sperber, C.; Tamburini, F.; Brunner, B.; Bernasconi, S. M.; Frossard, E.

    2015-07-01

    Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (myo-inositol hexakisphosphate, IP6) is an important form of Porg in many soils. The enzymatic hydrolysis of IP6 by phytase yields available Pi and less phosphorylated inositol derivates as products. The hydrolysis of organic P compounds by phosphatases leaves an isotopic imprint on the oxygen isotope composition (δ18O) of released Pi, which might be used to trace P in the environment. This study aims at determining the effect of phytase on the oxygen isotope composition of released Pi. For this purpose, enzymatic assays with histidine acid phytases from wheat and Aspergillus niger were prepared using IP6, adenosine 5'-monophosphate (AMP) and glycerophosphate (GPO4) as substrates. For a comparison to the δ18O of Pi released by other extracellular enzymes, enzymatic assays with acid phosphatases from potato and wheat germ with IP6 as a substrate were prepared. During the hydrolysis of IP6 by phytase, four of the six Pi were released, and one oxygen atom from water was incorporated into each Pi. This incorporation of oxygen from water into Pi was subject to an apparent inverse isotopic fractionation (ϵ ~ 6 to 10 ‰), which was similar to that imparted by acid phosphatase from potato during the hydrolysis of IP6 (ϵ ~ 7 ‰), where less than three Pi were released. The incorporation of oxygen from water into Pi during the hydrolysis of AMP and GPO4 by phytase yielded a normal isotopic fractionation (ϵ ~ -12 ‰), similar to values reported for acid phosphatases from potato and wheat germ. We attribute this similarity in ϵ to the same amino acid sequence motif (RHGXRXP) at the active site of these enzymes, which leads to similar reaction mechanisms. We suggest that the striking

  13. Reference spectra of important adsorbed organic and inorganic phosphate binding forms for soil P speciation using synchrotron-based K-edge XANES spectroscopy.

    PubMed

    Prietzel, Jörg; Harrington, Gertraud; Häusler, Werner; Heister, Katja; Werner, Florian; Klysubun, Wantana

    2016-03-01

    Direct speciation of soil phosphorus (P) by linear combination fitting (LCF) of P K-edge XANES spectra requires a standard set of spectra representing all major P species supposed to be present in the investigated soil. Here, available spectra of free- and cation-bound inositol hexakisphosphate (IHP), representing organic P, and of Fe, Al and Ca phosphate minerals are supplemented with spectra of adsorbed P binding forms. First, various soil constituents assumed to be potentially relevant for P sorption were compared with respect to their retention efficiency for orthophosphate and IHP at P levels typical for soils. Then, P K-edge XANES spectra for orthophosphate and IHP retained by the most relevant constituents were acquired. The spectra were compared with each other as well as with spectra of Ca, Al or Fe orthophosphate and IHP precipitates. Orthophosphate and IHP were retained particularly efficiently by ferrihydrite, boehmite, Al-saturated montmorillonite and Al-saturated soil organic matter (SOM), but far less efficiently by hematite, Ca-saturated montmorillonite and Ca-saturated SOM. P retention by dolomite was negligible. Calcite retained a large portion of the applied IHP, but no orthophosphate. The respective P K-edge XANES spectra of orthophosphate and IHP adsorbed to ferrihydrite, boehmite, Al-saturated montmorillonite and Al-saturated SOM differ from each other. They also are different from the spectra of amorphous FePO4, amorphous or crystalline AlPO4, Ca phosphates and free IHP. Inclusion of reference spectra of orthophosphate as well as IHP adsorbed to P-retaining soil minerals in addition to spectra of free or cation-bound IHP, AlPO4, FePO4 and Ca phosphate minerals in linear combination fitting exercises results in improved fit quality and a more realistic soil P speciation. A standard set of P K-edge XANES spectra of the most relevant adsorbed P binding forms in soils is presented. PMID:26917141

  14. Mutational analysis of the active site of indoleglycerol phosphate synthase from Escherichia coli.

    PubMed Central

    Darimont, B.; Stehlin, C.; Szadkowski, H.; Kirschner, K.

    1998-01-01

    Indoleglycerol phosphate synthase catalyzes the ring closure of 1-(2-carboxyphenylamino)-1-deoxyribulose 5'-phosphate to indoleglycerol phosphate, the fifth step in the pathway of tryptophan biosynthesis from chorismate. Because chemical synthesis of indole derivatives from arylamino ketones requires drastic solvent conditions, it is interesting by what mechanism the enzyme catalyzes the same condensation reaction. Seven invariant polar residues in the active site of the enzyme from Escherichia coli have been mutated directly or randomly, to identify the catalytically essential ones. A strain of E. coli suitable for selecting and classifying active mutants by functional complementation was constructed by precise deletion of the trpC gene from the genome. Judged by growth rates of transformants on selective media, mutants with either S58 or S60 replaced by alanine were indistinguishable from the wild-type, but R186 replaced by alanine was still partially active. Saturation random mutagenesis of individual codons showed that E53 was partially replaceable by aspartate and cysteine, whereas K114, E163, and N184 could not be replaced by any other residue. Partially active mutant proteins were purified and their steady-state kinetic and inhibitor binding constants determined. Their relative catalytic efficiencies paralleled their relative complementation efficiencies. These results are compatible with the location of the essential residues in the active site of the enzyme and support a chemically plausible catalytic mechanism. It involves two enzyme-bound intermediates and general acid-base catalysis by K114 and E163 with the support of E53 and N184. PMID:9605328

  15. Incorporation of /sup 14/C from glucose into amino acids in brain in vitro in the presence of organo- and inorganic lead and pyridoxal phosphate

    SciTech Connect

    Regunathan, S.; Sundaresan, R.

    1983-12-05

    The incorporation of label from U/sup 14/C glucose into glutamic acid, glutamine and GABA remained unaltered with the presence of lead acetate in the medium whereas tetraethyl lead (TEL) affected the incorporation in a characteristic manner in different regions of brain. Glucose uptake however was not influenced by TEL. Pyridoxal phosphate was found to reverse the effect of TEL on the incorporation especially in cerebellum and brainstem but with little effect in cerebral cortex. These findings suggest that the alterations in the GABA metabolism in TEL toxicity could be restored to some extent by pyridoxine in discrete brain areas.

  16. Type I phosphatidylinositol 4-phosphate 5-kinase homo- and heterodimerization determines its membrane localization and activity.

    PubMed

    Lacalle, Rosa Ana; de Karam, Juan C; Martínez-Muñoz, Laura; Artetxe, Ibai; Peregil, Rosa M; Sot, Jesús; Rojas, Ana M; Goñi, Félix M; Mellado, Mario; Mañes, Santos

    2015-06-01

    Type I phosphatidylinositol 4-phosphate 5-kinases (PIP5KIs; α, β, and γ) are a family of isoenzymes that produce phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] using phosphatidylinositol 4-phosphate as substrate. Their structural homology with the class II lipid kinases [type II phosphatidylinositol 5-phosphate 4-kinase (PIP4KII)] suggests that PIP5KI dimerizes, although this has not been formally demonstrated. Neither the hypothetical structural dimerization determinants nor the functional consequences of dimerization have been studied. Here, we used Förster resonance energy transfer, coprecipitation, and ELISA to show that PIP5KIβ forms homo- and heterodimers with PIP5KIγ_i2 in vitro and in live human cells. Dimerization appears to be a general phenomenon for PIP5KI isoenzymes because PIP5KIβ/PIP5KIα heterodimers were also detected by mass spectrometry. Dimerization was independent of actin cytoskeleton remodeling and was also observed using purified proteins. Mutagenesis studies of PIP5KIβ located the dimerization motif at the N terminus, in a region homologous to that implicated in PIP4KII dimerization. PIP5KIβ mutants whose dimerization was impaired showed a severe decrease in PI(4,5)P2 production and plasma membrane delocalization, although their association to lipid monolayers was unaltered. Our results identify dimerization as an integral feature of PIP5K proteins and a central determinant of their enzyme activity. PMID:25713054

  17. Endocytosis of Ligand-Activated Sphingosine 1-Phosphate Receptor 1 Mediated by the Clathrin-Pathway.

    PubMed

    Reeves, Patrick M; Kang, Yuan-Lin; Kirchhausen, Tom

    2016-01-01

    The sphingosine 1-phosphate receptor 1 (S1PR1) is one of five G protein-coupled receptors activated by the lipid sphingosine 1-phosphate (S1P). Stimulation of S1PR1 by binding S1P or the synthetic agonist FTY720P results in rapid desensitization, associated in part with depletion of receptor from the cell surface. We report here combining spinning disc confocal fluorescence microscopy and flow cytometry to show that rapid internalization of activated S1PR1 relies on a functional clathrin-mediated endocytic pathway. Uptake of activated S1PR1 was strongly inhibited in cells disrupted in their clathrin-mediated endocytosis by depleting clathrin or AP-2 or by treating cells with dynasore-OH. The uptake of activated S1P1R was strongly inhibited in cells lacking both β-arrestin 1 and β-arrestin 2, indicating that activated S1PR1 follows the canonical route of endocytosis for G-protein coupled receptor's (GPCR)'s. PMID:26481905

  18. Inorganic nanoparticles and the immune system: detection, selective activation and tolerance

    NASA Astrophysics Data System (ADS)

    Bastús, Neus G.; Sánchez-Tilló, Ester; Pujals, Silvia; Comenge, Joan; Giralt, Ernest; Celada, Antonio; Lloberas, Jorge; Puntes, Victor F.

    2012-03-01

    The immune system is the responsible for body integrity and prevention of external invasion. On one side, nanoparticles are no triggers that the immune system is prepared to detect, on the other side it is known that foreign bodies, not only bacteria, viruses and parasites, but also inorganic matter, can cause various pathologies such as silicosis, asbestosis or inflammatory reactions. Therefore, nanoparticles entering the body, after interaction with proteins, will be either recognized as self-agents or detected by the immune system, encompassing immunostimulation or immunosuppression responses. The nature of these interactions seems to be dictated not specially by the composition of the material but by modifications of NP coating (composition, surface charge and structure). Herein, we explore the use of gold nanoparticles as substrates to carry multifunctional ligands to manipulate the immune system in a controlled manner, from undetection to immunostimulation. Murine bone marrow macrophages can be activated with artificial nanometric objects consisting of a gold nanoparticle functionalized with peptides. In the presence of some conjugates, macrophage proliferation was stopped and pro-inflammatory cytokines were induced. The biochemical type of response depended on the type of conjugated peptide and was correlated with the degree of ordering in the peptide coating. These findings help to illustrate the basic requirements involved in medical NP conjugate design to either activate the immune system or hide from it, in order to reach their targets before being removed by phagocytes. Additionally, it opens up the possibility to modulate the immune response in order to suppress unwanted responses resulting from autoimmunity, or allergy or to stimulate protective responses against pathogens.

  19. Alkalosis and Dialytic Clearance of Phosphate Increases Phosphatase Activity: A Hidden Consequence of Hemodialysis

    PubMed Central

    Villa-Bellosta, Ricardo; González-Parra, Emilio; Egido, Jesús

    2016-01-01

    Background Extracellular pyrophosphate is a potent endogenous inhibitor of vascular calcification, which is degraded by alkaline phosphatase (ALP) and generated by hydrolysis of ATP via ectonucleotide pyrophosphatase/phosphodiesterase 1 (eNPP1). ALP activity (as routinely measured in clinical practice) represents the maximal activity (in ideal conditions), but not the real activity (in normal or physiological conditions). For the first time, the present study investigated extracellular pyrophosphate metabolism during hemodialysis sessions (including its synthesis via eNPP1 and its degradation via ALP) in physiological conditions. Methods and Findings 45 patients in hemodialysis were studied. Physiological ALP activity represents only 4–6% of clinical activity. ALP activity increased post-hemodialysis by 2% under ideal conditions (87.4 ± 3.3 IU/L vs. 89.3 ± 3.6 IU/L) and 48% under physiological conditions (3.5 ± 0.2 IU/L vs. 5.2 ± 0.2 IU/L). Pyrophosphate synthesis by ATP hydrolysis remained unaltered post-hemodialysis. Post-hemodialysis plasma pH (7.45 ± 0.02) significantly increased compared with the pre-dialysis pH (7.26 ± 0.02). The slight variation in pH (~0.2 units) induced a significant increase in ALP activity (9%). Addition of phosphate in post-hemodialysis plasma significantly decreased ALP activity, although this effect was not observed with the addition of urea. Reduction in phosphate levels and increment in pH were significantly associated with an increase in physiological ALP activity post-hemodialysis. A decrease in plasma pyrophosphate levels (3.3 ± 0.3 μmol/L vs. 1.9 ± 0.1 μmol/L) and pyrophosphate/ATP ratio (1.9 ± 0.2 vs. 1.4 ± 0.1) post-hemodialysis was also observed. Conclusion Extraction of uremic toxins, primarily phosphate and hydrogen ions, dramatically increases the ALP activity under physiological conditions. This hitherto unknown consequence of hemodialysis suggests a reinterpretation of the clinical value of this parameter

  20. Reducing the genetic redundancy of Arabidopsis PHOSPHATE TRANSPORTER1 transporters to study phosphate uptake and signaling.

    PubMed

    Ayadi, Amal; David, Pascale; Arrighi, Jean-François; Chiarenza, Serge; Thibaud, Marie-Christine; Nussaume, Laurent; Marin, Elena

    2015-04-01

    Arabidopsis (Arabidopsis thaliana) absorbs inorganic phosphate (Pi) from the soil through an active transport process mediated by the nine members of the PHOSPHATE TRANSPORTER1 (PHT1) family. These proteins share a high level of similarity (greater than 61%), with overlapping expression patterns. The resulting genetic and functional redundancy prevents the analysis of their specific roles. To overcome this difficulty, our approach combined several mutations with gene silencing to inactivate multiple members of the PHT1 family, including a cluster of genes localized on chromosome 5 (PHT1;1, PHT1;2, and PHT1;3). Physiological analyses of these lines established that these three genes, along with PHT1;4, are the main contributors to Pi uptake. Furthermore, PHT1;1 plays an important role in translocation from roots to leaves in high phosphate conditions. These genetic tools also revealed that some PHT1 transporters likely exhibit a dual affinity for phosphate, suggesting that their activity is posttranslationally controlled. These lines display significant phosphate deficiency-related phenotypes (e.g. biomass and yield) due to a massive (80%-96%) reduction in phosphate uptake activities. These defects limited the amount of internal Pi pool, inducing compensatory mechanisms triggered by the systemic Pi starvation response. Such reactions have been uncoupled from PHT1 activity, suggesting that systemic Pi sensing is most probably acting downstream of PHT1. PMID:25670816

  1. Protein phosphorylation as a mechanism for regulation of spinach leaf sucrose-phosphate synthase activity

    SciTech Connect

    Huber, J.L.A.; Huber, S.C. )

    1989-04-01

    Protein phosphorylation has been identified as a mechanism for the light-dark regulation of spinach sucrose-phosphate synthase (SPS) activity, previously shown to involve some type of covalent modification of the enzyme. The 120 kD subunit of SPS in extracts of light-treated leaves was labeled with {sup 32}P in the presence of ({gamma}-{sup 32}P) ATP. In this in vitro system, {sup 32}P incorporation into light-activated SPS was dependent upon ATP and magnesium concentrations as well as time, and was closely paralleled by inactivation of the enzyme. The soluble protein kinase involved in the interconversion of SPS between activated and deactivated forms may be specific for SPS as it co-purifies with SPS during partial purification of the enzyme. The kinase appears not to be calcium activated and no evidence has been obtained for metabolite control of SPS phosphorylation/inactivation.

  2. On the reactive adsorption of ammonia on activated carbons modified by impregnation with inorganic compounds.

    PubMed

    Bandosz, Teresa J; Petit, Camille

    2009-10-15

    Ammonia adsorption was studied under dynamic conditions, at room temperature, on activated carbons of different origins (coal-based, wood-based and coconut-shell-based carbons) before and after their impregnation with various inorganic compounds including metal chlorides, metal oxides and polycations. The role of humidity was evaluated by running tests in both dry and moist conditions. Adsorbents were analyzed before and after exposure to ammonia by thermal analyses, sorption of nitrogen, potentiometric titration, X-ray diffraction and FTIR spectroscopy. Results of breakthrough tests show significant differences in terms of adsorption capacity depending on the parent carbon, the impregnates and the experimental conditions. It is found that surface chemistry governs ammonia adsorption on the impregnated carbons. More precisely, it was demonstrated that a proper combination of the surface pH, the strength, type and amount of functional groups present on the adsorbents' surface is a key point in ammonia uptake. Water can have either positive or negative effects on the performance of adsorbents. It can enhance NH(3) adsorption capacity since it favors ammonia dissolution and thus enables reaction between ammonium ions and carboxylic groups from the carbons' surface. On the other hand, water can also reduce the performance from the strength of adsorption standpoint. It promotes dissolution of ammonia and that ammonia is first removed from the system when the adsorbent bed is purged with air. Ammonia, besides adsorption by van der Waals forces and dissolution in water, is also retained on the surface via reactive mechanisms such as acid-base reactions (Brønsted and Lewis) or complexation. Depending on the materials used and the experimental conditions, 6-47% ammonia adsorbed is strongly retained on the surface even when the bed is purged with air. PMID:19615690

  3. On the reactive adsorption of ammonia on activated carbons modified by impregnation with inorganic compounds

    SciTech Connect

    Bandosz, T.J.; Petit, C.

    2009-10-15

    Ammonia adsorption was studied under dynamic conditions, at room temperature, on activated carbons of different origins (coal-based, wood-based and coconut-shell-based carbons) before and after their impregnation with various inorganic compounds including metal chlorides, metal oxides and polycations. The role of humidity was evaluated by running tests in both dry and moist conditions. Adsorbents were analyzed before and after exposure to ammonia by thermal analyses, sorption of nitrogen, potentiometric titration, X-ray diffraction and FTIR spectroscopy. Results of breakthrough tests show significant differences in terms of adsorption capacity depending on the parent carbon, the impregnates and the experimental conditions. It is found that surface chemistry governs ammonia adsorption on the impregnated carbons. More precisely, it was demonstrated that a proper combination of the surface pH, the strength, type and amount of functional groups present on the adsorbents' surface is a key point in ammonia uptake. Water can have either positive or negative effects on the performance of adsorbents. It can enhance NH{sub 3} adsorption capacity since it favors ammonia dissolution and thus enables reaction between ammonium ions and carboxylic groups from the carbons' surface. On the other hand, water can also reduce the performance from the strength of adsorption standpoint. It promotes dissolution of ammonia and that ammonia is first removed from the system when the adsorbent bed is purged with air. Ammonia, besides adsorption by van der Waals forces and dissolution in water, is also retained on the surface via reactive mechanisms such as acid-base reactions (Bronsted and Lewis) or complexation. Depending on the materials used and the experimental conditions, 6-47% ammonia adsorbed is strongly retained on the surface even when the bed is purged with air.

  4. Inorganic arsenic represses interleukin-17A expression in human activated Th17 lymphocytes

    SciTech Connect

    Morzadec, Claudie; Macoch, Mélinda; Robineau, Marc; Sparfel, Lydie; Fardel, Olivier; Vernhet, Laurent

    2012-08-01

    Trivalent inorganic arsenic [As(III)] is an efficient anticancer agent used to treat patients suffering from acute promyelocytic leukemia. Recently, experimental studies have clearly demonstrated that this metalloid can also cure lymphoproliferative and/or pro-inflammatory syndromes in different murine models of chronic immune-mediated diseases. T helper (Th) 1 and Th17 lymphocytes play a central role in development of these diseases, in mice and humans, especially by secreting the potent pro-inflammatory cytokine interferon-γ and IL-17A, respectively. As(III) impairs basic functions of human T cells but its ability to modulate secretion of pro-inflammatory cytokines by differentiated Th lymphocytes is unknown. In the present study, we demonstrate that As(III), used at concentrations clinically achievable in plasma of patients, has no effect on the secretion of interferon-γ from Th1 cells but almost totally blocks the expression and the release of IL-17A from human Th17 lymphocytes co-stimulated for five days with anti-CD3 and anti-CD28 antibodies, in the presence of differentiating cytokines. In addition, As(III) specifically reduces mRNA levels of the retinoic-related orphan receptor (ROR)C gene which encodes RORγt, a key transcription factor controlling optimal IL-17 expression in fully differentiated Th17 cells. The metalloid also blocks initial expression of IL-17 gene induced by the co-stimulation, probably in part by impairing activation of the JNK/c-Jun pathway. In conclusion, our results demonstrate that As(III) represses expression of the major pro-inflammatory cytokine IL-17A produced by human Th17 lymphocytes, thus strengthening the idea that As(III) may be useful to treat inflammatory immune-mediated diseases in humans. -- Highlights: ► Arsenic inhibits secretion of IL-17A from human naïve and memory Th17 lymphocytes. ► Arsenic represses early expression of IL-17A gene in human activated T lymphocytes. ► Arsenic interferes with activation of

  5. Dosage Compensation in DROSOPHILA MELANOGASTER Triploids. II. Glucose-6-Phosphate Dehydrogenase Activity

    PubMed Central

    Maroni, Gustavo; Plaut, Walter

    1973-01-01

    The level of activity of the enzyme glucose-6-phosphate dehydrogenase was determinel in flies having seven different chromosomic constitutions. All those having an integral number of chromosomes [XAA, XXAA, XAAA, XXAAA, and XXXAAA (X=X chromosome, A=set of autosomes)] were found to have similar units of enzyme activity/mg live weight, while diploid females with a duplication and triploid females with a deficiency showed dosage effect. The amount of enzyme activity per cell, on the other hand, is also independent of the number of X's present but appears roughly proportional to the number of sets of autosomes.—It is proposed that dosage-compensated sex-linked genes are controlled by a positively acting regulatory factor(s) of autosomal origin. With this hypothesis it is possible to explain dosage compensation as a consequence of general regulatory mechanisms without invoking a special device which applies only to the X chromosomes. PMID:17248620

  6. Effect of CCK-8 on pentose phosphate shunt activity, pyridine nucleotides, and glucokinase of rat islets

    SciTech Connect

    Verspohl, E.J.; Breuning, I.; Ammon, H.P.

    1989-01-01

    In rat pancreatic islets the effects of cholecystokinin octapeptide (CCK-8) on pentose phosphate shunt (PPS) activity, glucokinase and hexokinase activity, and NADPH, NADP+, NADH, and NAD+ were studied. By elevating the glucose concentration from 3.0 to 8.3 and 16.7 mM the oxidation of (1-14C)- and (6-14C)glucose and the calculated PPS activity were increased in a concentration-dependent manner; 10 nM CCK-8 enhanced selectively the effect on (1-14C)glucose oxidation thereby increasing the PPS activity but only at an intermediate glucose concentration (8.3 mM). CCK-8 had no effect on glucokinase or hexokinase activity and CCK-8 did not influence glucose utilization. By elevating the glucose concentration, total NADPH and NADH were increased and total NADP+ and NAD+ were decreased. CCK-8 (10 nM) increased selectively NADPH and decreased NADP+ but did not change NADH or NAD+; the effect of CCK-8 on NADPH and NADH was only observed in the presence of an intermediate stimulatory glucose concentration (8.3 mM) but not at either a substimulatory glucose concentration or a maximally stimulatory glucose concentration for insulin release (3.0 or 16.7 mM). The data indicate first that CCK-8 does not act on glucose phosphorylation or glucose utilization and second that CCK-8 increases PPS activity and NADPH levels in rat pancreatic islets. Since the concentrations of glucose necessary for these CCK-8 effects are in the range of 8.3 mM and parallel with those necessary for insulin release as shown in earlier observations, glucose oxidation via pentose phosphate shunt and NADPH are suggested to be related to the CCK-8-modulated insulin release.

  7. Overexpression of SIRT5 confirms its involvement in deacetylation and activation of carbamoyl phosphate synthetase 1.

    PubMed

    Ogura, Masahito; Nakamura, Yasuhiko; Tanaka, Daisuke; Zhuang, Xiaotong; Fujita, Yoshihito; Obara, Akio; Hamasaki, Akihiro; Hosokawa, Masaya; Inagaki, Nobuya

    2010-02-26

    SIR2 protein, an NAD-dependent deacetylase, is localized to nucleus and is involved in life span extension by calorie restriction in yeast. In mammals, among the seven SIR2 homologues (SIRT1-7), SIRT3, 4, and 5 are localized to mitochondria. As SIRT5 mRNA levels in liver are increased by fasting, the physiological role of SIRT5 was investigated in liver of SIRT5-overexpressing transgenic (SIRT5 Tg) mice. We identified carbamoyl phosphate synthetase 1 (CPS1), a key enzyme of the urea cycle that catalyzes condensation of ammonia with bicarbonate to form carbamoyl phosphate, as a target of SIRT5 by two-dimensional electrophoresis comparing mitochondrial proteins in livers of SIRT5 Tg and wild-type mice. CPS1 protein was more deacetylated and activated in liver of SIRT5 Tg mice than in wild-type. In addition, urea production was upregulated in hepatocytes of SIRT5 Tg mice. These results agree with those of a previous study using SIRT5 knockout (KO) mice. Because ammonia generated during fasting is toxic, SIRT5 protein might play a protective role by converting ammonia to non-toxic urea through deacetylation and activation of CPS1. PMID:20097174

  8. The structural role of manganese ions in soil active silicate-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Szumera, Magdalena

    2014-08-01

    Silicate-phosphate glasses of SiO2sbnd P2O5sbnd K2Osbnd MgOsbnd CaO system containing manganese ions were synthesized by the melt-quenching technique and were investigated to obtain information about the influence of Mn-cations on the glass structure and their chemical activity. Structural properties were studied using X-ray method, FTIR and Raman spectroscopies. The chemical activity of analyzed glasses in the 2 wt.% citric acid solution was measured by chemical analysis (ICP-AES, EDS) and SEM observations. It has been found that increasing amount of MnO2 in the structure of investigated glasses causes their gradual depolymerization. This process is more apparent in the case of the silico-oxygen subnetwork than phospho-oxygen one. This is related to increasing amounts of SiO4 tetrahedra containing two nonbridging oxygen atoms in silico-oxygen subnetwork. It has been also found that the presence of “weaker” chemical bonds of Sisbnd Osbnd Mn type in comparison to Sisbnd Osbnd Ca and Sisbnd Osbnd Mg bonds is responsible for the increase in solubility of the analyzed silicate-phosphate glasses in conditions simulating natural soil environment.

  9. Enhancing the value of commodity polymers: Part 1. Structure-property relationships in composite materials based on maleated polypropylene/inorganic phosphate glasses. Part 2. New value-added applications for polyesters

    NASA Astrophysics Data System (ADS)

    Gupta, Mohit

    The first part of the thesis (Chapters 2 & 3) describes a new class of organic polymer/inorganic glass composite materials with property improvements that are impossible to achieve with classical polymer blends or composites. These materials exhibit good processability, superior mechanical performance, good thermal stability, and have excellent gas barrier properties. Low glass transition temperature phosphate glasses (Pglass) are used as inorganic fillers and slightly maleated polypropylene is used as the organic polymer matrix. The Pglass, which was dispersed as spherical droplets in the unoriented composites can be elongated into high aspect ratio platelets during the biaxial stretching process. Biaxially oriented films exhibited a brick wall type microstructure with highly aligned inorganic platelets in a ductile organic matrix and the oxygen barrier properties are significantly improved due to presence of Pglass platelets as impermeable inclusions. Mechanical properties of the biaxially oriented films showed significant improvements compared to neat polymer due to uniform dispersion of the Pglass platelets. Properly dispersed and aligned platelets have proven to be very effective for increasing the composite modulus. These developed materials therefore show promise to help fulfill the ever increasing demand for new advanced materials for a wide variety of advanced packaging applications because of their gas barrier properties, flexibility, transparency, mechanical strength and performance under humid conditions. The second part of the thesis (Chapters 4 & 5) describes new value-added applications for polyesters. Chapter 4 reports a novel process for the decolorization of green and blue colored PET bottle flakes using hydrogen peroxide. The decolorized flakes were characterized for color, intrinsic viscosity values. Decolorized flakes exhibited color values similar to those of colorless recycled PET and even though IV values decreased, bleached flakes still

  10. Phosphate, inositol and polyphosphates.

    PubMed

    Livermore, Thomas M; Azevedo, Cristina; Kolozsvari, Bernadett; Wilson, Miranda S C; Saiardi, Adolfo

    2016-02-15

    Eukaryotic cells have ubiquitously utilized the myo-inositol backbone to generate a diverse array of signalling molecules. This is achieved by arranging phosphate groups around the six-carbon inositol ring. There is virtually no biological process that does not take advantage of the uniquely variable architecture of phosphorylated inositol. In inositol biology, phosphates are able to form three distinct covalent bonds: phosphoester, phosphodiester and phosphoanhydride bonds, with each providing different properties. The phosphoester bond links phosphate groups to the inositol ring, the variable arrangement of which forms the basis of the signalling capacity of the inositol phosphates. Phosphate groups can also form the structural bridge between myo-inositol and diacylglycerol through the phosphodiester bond. The resulting lipid-bound inositol phosphates, or phosphoinositides, further expand the signalling potential of this family of molecules. Finally, inositol is also notable for its ability to host more phosphates than it has carbons. These unusual organic molecules are commonly referred to as the inositol pyrophosphates (PP-IPs), due to the presence of high-energy phosphoanhydride bonds (pyro- or diphospho-). PP-IPs themselves constitute a varied family of molecules with one or more pyrophosphate moiety/ies located around the inositol. Considering the relationship between phosphate and inositol, it is no surprise that members of the inositol phosphate family also regulate cellular phosphate homoeostasis. Notably, the PP-IPs play a fundamental role in controlling the metabolism of the ancient polymeric form of phosphate, inorganic polyphosphate (polyP). Here we explore the intimate links between phosphate, inositol phosphates and polyP, speculating on the evolution of these relationships. PMID:26862212

  11. [Effect of temperature acclimation on glucose-6-phosphate dehydrogenase activity in various tissues of the Mullus barbatus ponticus].

    PubMed

    Rusinova, O S

    1997-01-01

    Acclimation of the Mullus barbatus ponticus to the temperature fall (from 16 to 8 degrees C) induces an increase in the activity of glucose-6-phosphate dehydrogenase both in summer and in autumn. These changes are more expressed in the liver and red muscle than in the white ones. The values of Km of glucose-6-phosphate (only in autumn) and NADP are also higher at 8 than at 16 degrees C. Actinomycin D does not prevent from cold activation of this enzyme in liver only in autumn, when the activity of glucose-6-phosphate dehydrogenase is 8-10 times higher than in summer, and in the red muscle in the both seasons, although this injection decreases the level of enzyme activity in this muscle. This injection does not change the values of Km for glucose-6-phosphate and NADP. It is supposed that the activation of glucose-6-phosphate dehydrogenase in the liver and red muscle during cold adaptation may be a result of change of substrate-binding ability and enzyme interaction with NADP without changes in the enzyme biosynthesis. PMID:9606826

  12. Phosphatidylinositol-4-phosphate 5-Kinase Isoforms Exhibit Acyl Chain Selectivity for Both Substrate and Lipid Activator*

    PubMed Central

    Shulga, Yulia V.; Anderson, Richard A.; Topham, Matthew K.; Epand, Richard M.

    2012-01-01

    Phosphatidylinositol 4,5-bisphosphate is mostly produced in the cell by phosphatidylinositol-4-phosphate 5-kinases (PIP5K) and has a crucial role in numerous signaling events. Here we demonstrate that in vitro all three isoforms of PIP5K, α, β, and γ, discriminate among substrates with different acyl chains for both the substrates phosphatidylinositol 4-phosphate (PtdIns4P) and phosphatidylinositol (PtdIns) although to different extents, with isoform γ being the most selective. Fully saturated dipalmitoyl-PtdIns4P was a poor substrate for all three isoforms, but both the 1-stearoyl-2-arachidonoyl and the 1-stearoyl-2-oleoyl forms of PtdIns4P were good substrates. Vmax was greater for the 1-stearoyl-2-arachidonoyl form compared with the 1-stearoyl-2-oleoyl form, although for PIP5Kβ the difference was small. For the α and γ isoforms, Km was much lower for 1-stearoyl-2-oleoyl PtdIns4P, making this lipid the better substrate of the two under most conditions. Activation of PIP5K by phosphatidic acid is also acyl chain-dependent. Species of phosphatidic acid with two unsaturated acyl chains are much better activators of PIP5K than those containing one saturated and one unsaturated acyl chain. PtdIns is a poor substrate for PIP5K, but it also shows acyl chain selectivity. Curiously, there is no acyl chain discrimination among species of phosphatidic acid in the activation of the phosphorylation of PtdIns. Together, our findings indicate that PIP5K isoforms α, β, and γ act selectively on substrates and activators with different acyl chains. This could be a tightly regulated mechanism of producing physiologically active unsaturated phosphatidylinositol 4,5-bisphosphate species in the cell. PMID:22942276

  13. Improving the catalytic activity of isopentenyl phosphate kinase through protein coevolution analysis

    PubMed Central

    Liu, Ying; Yan, Zhihui; Lu, Xiaoyun; Xiao, Dongguang; Jiang, Huifeng

    2016-01-01

    Protein rational design has become more and more popular for protein engineering with the advantage of biological big-data. In this study, we described a method of rational design that is able to identify desired mutants by analyzing the coevolution of protein sequence. We employed this approach to evolve an archaeal isopentenyl phosphate kinase that can convert dimethylallyl alcohol (DMA) into precursor of isoprenoids. By designing 9 point mutations, we improved the catalytic activities of IPK about 8-fold in vitro. After introducing the optimal mutant of IPK into engineered E. coli strain for β-carotenoids production, we found that β-carotenoids production exhibited 97% increase over the starting strain. The process of enzyme optimization presented here could be used to improve the catalytic activities of other enzymes. PMID:27052337

  14. Improving the catalytic activity of isopentenyl phosphate kinase through protein coevolution analysis.

    PubMed

    Liu, Ying; Yan, Zhihui; Lu, Xiaoyun; Xiao, Dongguang; Jiang, Huifeng

    2016-01-01

    Protein rational design has become more and more popular for protein engineering with the advantage of biological big-data. In this study, we described a method of rational design that is able to identify desired mutants by analyzing the coevolution of protein sequence. We employed this approach to evolve an archaeal isopentenyl phosphate kinase that can convert dimethylallyl alcohol (DMA) into precursor of isoprenoids. By designing 9 point mutations, we improved the catalytic activities of IPK about 8-fold in vitro. After introducing the optimal mutant of IPK into engineered E. coli strain for β-carotenoids production, we found that β-carotenoids production exhibited 97% increase over the starting strain. The process of enzyme optimization presented here could be used to improve the catalytic activities of other enzymes. PMID:27052337

  15. Application of acid-activated Bauxsol for wastewater treatment with high phosphate concentration: Characterization, adsorption optimization, and desorption behaviors.

    PubMed

    Ye, Jie; Cong, Xiangna; Zhang, Panyue; Zeng, Guangming; Hoffmann, Erhard; Liu, Yang; Wu, Yan; Zhang, Haibo; Fang, Wei; Hahn, Hermann H

    2016-02-01

    Acid-activated Bauxsol was applied to treat wastewater with high phosphate concentration in a batch adsorption system in this paper. The effect of acid activation on the change of Bauxsol structure was systematically investigated. The mineralogical inhomogeneity and intensity of Bauxsol decreased after acid activation, and FeCl3·2H2O and Al(OH)3 became the dominant phases of acid-activated Bauxsol adsorption. Moreover, the BET surface area and total pore volume of Bauxsol increased after acid activation. Interaction of initial solution pH and adsorption temperature on phosphate adsorption onto acid-activated Bauxsol was investigated by using response surface methodology with central composite design. The maximum phosphate adsorption capacity of 192.94 mg g(-1) was achieved with an initial solution pH of 4.19 and an adsorption temperature of 52.18 °C, which increased by 7.61 times compared with that of Bauxsol (22.40 mg g(-1)), and was higher than other adsorbents. Furthermore, the desorption studies demonstrated that the acid-activated Bauxsol was successfully regenerated with 0.5 mol L(-1) HCl solution. The adsorption capacity and desorption efficiency of acid-activated Bauxsol maintained at 80.48% and 93.02% in the fifth adsorption-desorption cycle, respectively, suggesting that the acid-activated Bauxsol could be repeatedly used in wastewater treatment with high phosphate concentration. PMID:26606195

  16. Chromium liquid waste inertization in an inorganic alkali activated matrix: leaching and NMR multinuclear approach.

    PubMed

    Ponzoni, Chiara; Lancellotti, Isabella; Barbieri, Luisa; Spinella, Alberto; Saladino, Maria Luisa; Martino, Delia Chillura; Caponetti, Eugenio; Armetta, Francesco; Leonelli, Cristina

    2015-04-01

    A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid hazardous waste. The evolution of the process--from the precursor dissolution to the final geopolymer matrix hardening--of different geopolymers containing a waste amount ranging from 3 to 20%wt and their capability to inertize chromium cations were studied by: i) the leaching tests, according to the EN 12,457 regulation, at different curing times (15, 28, 90 and 540 days) monitoring releases of chromium ions (Cr(III) and Cr(VI)) and the cations constituting the aluminosilicate matrix (Na, Si, Al); ii) the humidity variation for different curing times (15 and 540 days); iii) SEM characterization at different curing times (28 and 540 days); iv) the trend of the solution conductivity and pH during the leaching test; v) the characterization of the short-range ordering in terms of TOT bonds (where T is Al or Si) by (29)Si and (27)Al solid state magic-angle spinning nuclear magnetic resonance (ss MAS NMR) for geopolymers containing high amounts of waste (10-20%wt). The results show the formation of a stable matrix after only 15 days independently on the waste amount introduced; the longer curing times increase the matrices stabilities and their ability to immobilize chromium cations. The maximum amount of waste that can be inertized is around 10 wt% after a curing time of 28 days

  17. Chloroplast Activity and 3'phosphadenosine 5'phosphate Signaling Regulate Programmed Cell Death in Arabidopsis.

    PubMed

    Bruggeman, Quentin; Mazubert, Christelle; Prunier, Florence; Lugan, Raphaël; Chan, Kai Xun; Phua, Su Yin; Pogson, Barry James; Krieger-Liszkay, Anja; Delarue, Marianne; Benhamed, Moussa; Bergounioux, Catherine; Raynaud, Cécile

    2016-03-01

    Programmed cell death (PCD) is a crucial process both for plant development and responses to biotic and abiotic stress. There is accumulating evidence that chloroplasts may play a central role during plant PCD as for mitochondria in animal cells, but it is still unclear whether they participate in PCD onset, execution, or both. To tackle this question, we have analyzed the contribution of chloroplast function to the cell death phenotype of the myoinositol phosphate synthase1 (mips1) mutant that forms spontaneous lesions in a light-dependent manner. We show that photosynthetically active chloroplasts are required for PCD to occur in mips1, but this process is independent of the redox state of the chloroplast. Systematic genetic analyses with retrograde signaling mutants reveal that 3'-phosphoadenosine 5'-phosphate, a chloroplast retrograde signal that modulates nuclear gene expression in response to stress, can inhibit cell death and compromises plant innate immunity via inhibition of the RNA-processing 5'-3' exoribonucleases. Our results provide evidence for the role of chloroplast-derived signal and RNA metabolism in the control of cell death and biotic stress response. PMID:26747283

  18. Beta glucosidase from Bacillus polymyxa is activated by glucose-6-phosphate.

    PubMed

    Weiss, Paulo H E; Álvares, Alice C M; Gomes, Anderson A; Miletti, Luiz C; Skoronski, Everton; da Silva, Gustavo F; de Freitas, Sonia M; Magalhães, Maria L B

    2015-08-15

    Optimization of cellulose enzymatic hydrolysis is crucial for cost effective bioethanol production from lignocellulosic biomass. Enzymes involved in cellulose hydrolysis are often inhibited by their end-products, cellobiose and glucose. Efforts have been made to produce more efficient enzyme variants that are highly tolerant to product accumulation; however, further improvements are still necessary. Based on an alternative approach we initially investigated whether recently formed glucose could be phosphorylated into glucose-6-phosphate to circumvent glucose accumulation and avoid inhibition of beta-glucosidase from Bacillus polymyxa (BGLA). The kinetic properties and structural analysis of BGLA in the presence of glucose-6-phosphate (G6P) were investigated. Kinetic studies demonstrated that enzyme was not inhibited by G6P. In contrast, the presence of G6P activated the enzyme, prevented beta glucosidase feedback inhibition by glucose accumulation and improved protein stability. G6P binding was investigated by fluorescence quenching experiments and the respective association constant indicated high affinity binding of G6P to BGLA. Data reported here are of great impact for future design strategies for second-generation bioethanol production. PMID:26116788

  19. Phosphate binding in the active centre of tomato multifunctional nuclease TBN1 and analysis of superhelix formation by the enzyme.

    PubMed

    Stránský, Jan; Koval', Tomáš; Podzimek, Tomáš; Týcová, Anna; Lipovová, Petra; Matoušek, Jaroslav; Kolenko, Petr; Fejfarová, Karla; Dušková, Jarmila; Skálová, Tereza; Hašek, Jindřich; Dohnálek, Jan

    2015-11-01

    Tomato multifunctional nuclease TBN1 belongs to the type I nuclease family, which plays an important role in apoptotic processes and cell senescence in plants. The newly solved structure of the N211D mutant is reported. Although the main crystal-packing motif (the formation of superhelices) is conserved, the details differ among the known structures. A phosphate ion was localized in the active site of the enzyme. The binding of the surface loop to the active centre is stabilized by the phosphate ion, which correlates with the observed aggregation of TBN1 in phosphate buffer. The conserved binding of the surface loop to the active centre suggests biological relevance of the contact in a regulatory function or in the formation of oligomers. PMID:26527269

  20. FTY720 Phosphate Activates Sphingosine-1-Phosphate Receptor 2 and Selectively Couples to Gα12/13/Rho/ROCK to Induce Myofibroblast Contraction.

    PubMed

    Sobel, Katrin; Monnier, Lucile; Menyhart, Katalin; Bolinger, Matthias; Studer, Rolf; Nayler, Oliver; Gatfield, John

    2015-06-01

    FTY720 phosphate (FTY720-P; 2-amino-2-[2-(4-octylphenyl)ethyl]-1,3-propanediol, monodihydrogen phosphate ester) is a nonselective sphingosine-1-phosphate (S1P) receptor agonist thought to be devoid of activity at the S1P2 receptor subtype. However, we have recently shown that FTY720-P displays significant S1P2 receptor agonist activity in recombinant cells and fibroblasts expressing endogenous S1P2 receptors. To elucidate the S1P2-dependent signaling pathways that were activated by FTY720-P, we employed second messenger assays and impedance-based assays in combination with pharmacological and small interfering RNA-based pathway inhibition in recombinant Chinese hamster ovary (CHO)-S1P2 cells as well as human lung myofibroblasts generated in vitro. In CHO-S1P2 cells, FTY720-P did not modulate cAMP or calcium levels. However, reporter-gene assays, impedance-based assays with a selective Rho-associated kinase (ROCK) inhibitor, Gα12/13 knockdown and activated Rho-pull-down assays demonstrated that FTY720-P potently activated Gα12/13/Rho/ROCK signaling. S1P similarly activated Gα12/13/Rho/ROCK signaling via S1P2 receptors, whereas the two selective S1P1 receptor agonists (Z,Z)-5-(3-chloro-4-[(2R)-2,3-dihydroxy-propoxy]-benzylidene)-2-propylimino-3-o-tolyl-thiazolidin-4-one (ponesimond) and 5-[4-phenyl-5-(trifluoromethyl)thiophen-2-yl]-3-[3-(trifluoromethyl)phenyl]1,2,4-oxadiazole (SEW2871) were inactive. In lung myofibroblasts, which mainly expressed the S1P2 receptor subtype, we showed that FTY720-P selectively activated the Gα12/13/Rho/ROCK pathway via the S1P2 receptor. Moreover, the activation of the Gα12/13/Rho/ROCK pathway in myofibroblasts by FTY720-P caused potent myofibroblast contraction similar to that induced by the natural ligand S1P. Thus, complementing second messenger assays with unbiased label-free assays or phenotypic assays in native expression systems can uncover activation of additional pathways, such as Gα12/13/Rho/ROCK signaling. PMID

  1. Influence of phosphate and pH on myofibrillar ATPase activity and force in skinned cardiac trabeculae from rat.

    PubMed Central

    Ebus, J P; Stienen, G J; Elzinga, G

    1994-01-01

    1. The effects of inorganic phosphate (Pi) and pH on maximal calcium-activated isometric force and MgATPase activity were studied in chemically skinned cardiac trabeculae from rat. ATP hydrolysis was coupled enzymatically to the breakdown of NADH, and its concentration was determined photometrically. Measurements were performed at 2.1 microns sarcomere length and 20 degrees C. ATPase activity and force were also determined when square-wave-shaped length changes were applied, with a frequency of 23 Hz and an amplitude of 2.5%. 2. At pH 7.0 without added Pi, the average isometric force (+/- S.E.M.) was 51 +/- 3 kN m-2 (n = 23). The average isometric ATPase activity was 0.43 +/- 0.02 mM s-1 (n = 23). During the changes in length ATPase activity increased to 152 +/- 3% of the isometric value, while the average force level decreased to 48 +/- 2%. 3. Isometric force gradually decreased to 31 +/- 2% of the control value when the Pi concentration was increased to 30 mM. Isometric ATPase activity, however, remained constant for Pi concentrations up to 5 mM and decreased to 87 +/- 3% at 30 mM Pi. When Pi accumulation inside the preparation due to ATP hydrolysis was taken into account, a linear relationship was found between isometric force and log [Pi]. The decrease in relative force was found to be 44 +/- 4% per decade. 4. During the length changes, ATPase activity and average force showed, apart from the increase in ATPase activity and decrease in average force, the same dependence on Pi as the isometric values. Stiffness, estimated from the amplitude of the force responses during the length changes, decreased in proportion to isometric force when the Pi concentration was increased. The changes in the shape of the force responses due to the repetitive changes in length as a function of the Pi concentration were relatively small. These results suggest that the effect of Pi on the transitions which influence ATP turnover is rather insensitive to changes in cross

  2. Escherichia coli N-Acetylglucosamine-1-Phosphate-Uridyltransferase/Glucosamine-1-Phosphate-Acetyltransferase (GlmU) Inhibitory Activity of Terreic Acid Isolated from Aspergillus terreus.

    PubMed

    Sharma, Rashmi; Lambu, Mallikharjuna Rao; Jamwal, Urmila; Rani, Chitra; Chib, Reena; Wazir, Priya; Mukherjee, Debaraj; Chaubey, Asha; Khan, Inshad Ali

    2016-04-01

    Secondary metabolite of Aspergillus terreus, terreic acid, is a reported potent antibacterial that was identified more than 60 years ago, but its cellular target(s) are still unknown. Here we screen its activity against the acetyltransferase domain of a bifunctional enzyme, Escherichia coli N-acetylglucosamine-1-phosphate-uridyltransferase/glucosamine-1-phosphate-acetyltransferase (GlmU). An absorbance-based assay was used to screen terreic acid against the acetyltransferase activity of E. coli GlmU. Terreic acid was found to inhibit the acetyltransferase domain of E. coli GlmU with an IC50 of 44.24 ± 1.85 µM. Mode of inhibition studies revealed that terreic acid was competitive with AcCoA and uncompetitive with GlcN-1-P. It also exhibited concentration-dependent killing of E. coli ATCC 25922 up to 4× minimum inhibitory concentration and inhibited the growth of biofilms generated by E. coli. Characterization of resistant mutants established mutation in the acetyltransferase domain of GlmU. Terreic acid was also found to be metabolically stable in the in vitro incubations with rat liver microsome in the presence of a NADPH regenerating system. The studies reported here suggest that terreic acid is a potent antimicrobial agent and support that E. coli GlmU acetyltransferase is a molecular target of terreic acid, resulting in its antibacterial activity. PMID:26762501

  3. Molecular Basis of Reduced Pyridoxine 5′-Phosphate Oxidase Catalytic Activity in Neonatal Epileptic Encephalopathy Disorder*

    PubMed Central

    Musayev, Faik N.; Di Salvo, Martino L.; Saavedra, Mario A.; Contestabile, Roberto; Ghatge, Mohini S.; Haynes, Alexina; Schirch, Verne; Safo, Martin K.

    2009-01-01

    Mutations in pyridoxine 5′-phosphate oxidase are known to cause neonatal epileptic encephalopathy. This disorder has no cure or effective treatment and is often fatal. Pyridoxine 5′-phosphate oxidase catalyzes the oxidation of pyridoxine 5′-phosphate to pyridoxal 5′-phosphate, the active cofactor form of vitamin B6 required by more than 140 different catalytic activities, including enzymes involved in amino acid metabolism and biosynthesis of neurotransmitters. Our aim is to elucidate the mechanism by which a homozygous missense mutation (R229W) in the oxidase, linked to neonatal epileptic encephalopathy, leads to reduced oxidase activity. The R229W variant is ∼850-fold less efficient than the wild-type enzyme due to an ∼192-fold decrease in pyridoxine 5′-phosphate affinity and an ∼4.5-fold decrease in catalytic activity. There is also an ∼50-fold reduction in the affinity of the R229W variant for the FMN cofactor. A 2.5 Å crystal structure of the R229W variant shows that the substitution of Arg-229 at the FMN binding site has led to a loss of hydrogen-bond and/or salt-bridge interactions between FMN and Arg-229 and Ser-175. Additionally, the mutation has led to an alteration of the configuration of a β-strand-loop-β-strand structure at the active site, resulting in loss of two critical hydrogen-bond interactions involving residues His-227 and Arg-225, which are important for substrate binding and orientation for catalysis. These results provide a molecular basis for the phenotype associated with the R229W mutation, as well as providing a foundation for understanding the pathophysiological consequences of pyridoxine 5′-phosphate oxidase mutations. PMID:19759001

  4. Highly active cobalt phosphate and borate based oxygen evolving catalysts operating in neutral and natural waters

    SciTech Connect

    Esswein, AJ; Surendranath, Y; Reece, SY; Nocera, DG

    2011-02-01

    A high surface area electrode is functionalized with cobalt-based oxygen evolving catalysts (Co-OEC = electrodeposited from pH 7 phosphate, Pi, pH 8.5 methylphosphonate, MePi, and pH 9.2 borate electrolyte, Bi). Co-OEC prepared from MePi and operated in Pi and Bi achieves a current density of 100 mA cm(-2) for water oxidation at 442 and 363 mV overpotential, respectively. The catalyst retains activity in near-neutral pH buffered electrolyte in natural waters such as those from the Charles River (Cambridge, MA) and seawater (Woods Hole, MA). The efficacy and ease of operation of anodes functionalized with Co-OEC at appreciable current density together with its ability to operate in near neutral pH buffered natural water sources bodes well for the translation of this catalyst to a viable renewable energy storage technology.

  5. Potassium ion-activated hydrolysis of p-nitrophenyl phosphate in pancreatic islet-cell membranes.

    PubMed Central

    Lernmark, A; Parman, A; Täljedal, I B

    1977-01-01

    Hydrolysis of p-nitrophenyl phosphate was measured in a fraction enriched in plasma membranes from pancreatic islets of non-inbred ob/ob mice. Hydrolysis was stimulated by K+ (10mM) in the pH range 5--10; a small peak of K+-induced activation was observed between pH7.5 and 8. Both the K+-induced activation and the hydrolysis in the absence of K+ were Mg2+-dependent; maximum activation was obtained with 10mM-K+ plus 5 mM-Mg2+. Rb+ was as effective an activator as K+. Ouabain was inhibitory, the effect being inversely related to the K+ concentration; 0.1--0.2mM-ouabain caused about 50% inhibition in the presence of 1 mM-K+, but had no demonstrable effect in the presence of 4--5mM-K+. The K+-stimulated activity was markedly inhibited by 0.1mM-ATP, 35--140 MM-Na+, or 0.01 mM-p-chloromercuribenzenesulphonic acid. Similarities to Rb+ accumulation suggest that catalysis of univalent cation flow in pancreatic beta-cells may be coupled to a phosphoryl-transfer reaction with ATP as natural substrate or regulator. PMID:20876

  6. Immobilization and phytotoxicity of Pb in contaminated soil amended with γ-polyglutamic acid, phosphate rock, and γ-polyglutamic acid-activated phosphate rock.

    PubMed

    Zhu, Jun; Cai, Zhijian; Su, Xiaojuan; Fu, Qingling; Liu, Yonghong; Huang, Qiaoyun; Violante, Antonio; Hu, Hongqing

    2015-02-01

    Pot experiments were conducted to investigate the effects of γ-polyglutamic acid (γ-PGA), phosphate rock (PR), and γ-PGA-activated PR (γ-PGA-PR) on the immobilization and phytotoxicity of Pb in a contaminated soil. The proportion of residual Pb (Re-Pb) in soil was reduced by the addition of γ-PGA but was increased by the application of PR and γ-PGA-PR. The addition of γ-PGA in soil improved the accumulation of Pb in pak choi and decreased the growth of pak choi, suggesting the intensification of Pb phytotoxicity to pak choi. However, opposite effects of PR and γ-PGA-PR on the phytotoxicity of Pb to pak choi in soil were observed. Moreover, in the examined range, γ-PGA-PR activated by a higher amount of γ-PGA resulted in a greater proportion of Re-Pb in soil and weaker phytotoxicity of Pb to pak choi. The predominance of γ-PGA-PR in relieving the phytotoxicity of Pb was ascribed mainly to the increase of soil pH and available phosphate after the amendment, which could facilitate the precipitation of Pb in soil and provide pak choi with more phosphorus nutrient. PMID:25196962

  7. Impact of organic and inorganic fertilizers application on the phytochemical and antioxidant activity of Kacip Fatimah (Labisia pumila Benth).

    PubMed

    Ibrahim, Mohd Hafiz; Jaafar, Hawa Z E; Karimi, Ehsan; Ghasemzadeh, Ali

    2013-01-01

    A study was conducted to compare secondary metabolites and antioxidant activity of Labisia pumila Benth (Kacip Fatimah) in response to two sources of fertilizer [i.e., organic (chicken dung; 10% N:10% P₂O₅:10% K₂O) and inorganic fertilizer (NPK green; 15% N, 15% P₂O₅, 15% K₂O)] under different N rates of 0, 90, 180 and 270 kg N/ha. The experiment was arranged in a randomized complete block design replicated three times. At the end of 15 weeks, it was observed that the application of organic fertilizer enhanced the production of total phenolics, flavonoids, ascorbic acid, saponin and gluthathione content in L. pumila, compared to the use of inorganic fertilizer. The nitrate content was also reduced under organic fertilization. The application of nitrogen at 90 kg N/ha improved the production of secondary metabolites in Labisia pumila. Higher rates in excess of 90 kg N/ha reduced the level of secondary metabolites and antioxidant activity of this herb. The DPPH and FRAP activity was also highest at 90 kg N/ha. The results indicated that the use of chicken dung can enhance the production of secondary metabolites and improve antioxidant activity of this herb. PMID:24013410

  8. Osteogenic activity of cyclodextrin-encapsulated doxycycline in a calcium phosphate PCL and PLGA composite.

    PubMed

    Trajano, V C C; Costa, K J R; Lanza, C R M; Sinisterra, R D; Cortés, M E

    2016-07-01

    Composites of biodegradable polymers and calcium phosphate are bioactive and flexible, and have been proposed for use in tissue engineering and bone regeneration. When associated with the broad-spectrum antibiotic doxycycline (DOX), they could favor antimicrobial action and enhance the action of osteogenic composites. Composites of polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), and a bioceramic of biphasic calcium phosphate Osteosynt® (BCP) were loaded with DOX encapsulated in β-cyclodextrin (βCD) and were evaluated for effects on osteoblastic cell cultures. The DOX/βCD composite was prepared with a double mixing method. Osteoblast viability was assessed with methyl tetrazolium (MTT) assays after 1day, 7day, and 14days of composite exposure; alkaline phosphatase (AP) activity and collagen production were evaluated after 7days and 14days, and mineral nodule formation after 14days. Composite structures were evaluated by scanning electron microscopy (SEM). Osteoblasts exposed to the composite containing 25μg/mL DOX/βCD had increased cell proliferation (p<0.05) compared to control osteoblast cultures at all experimental time points, reaching a maximum in the second week. AP activity and collagen secretion levels were also elevated in osteoblasts exposed to the DOX/βCD composite (p<0.05 vs. controls) and reached a maximum after 14days. These results were corroborated by Von Kossa test results, which showed strong formation of mineralization nodules during the same time period. SEM of the composite material revealed a surface topography with pore sizes suitable for growing osteoblasts. Together, these results suggest that osteoblasts are viable, proliferative, and osteogenic in the presence of a DOX/βCD-containing BCP ceramic composite. PMID:27127066

  9. Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by sol-gel processes.

    PubMed

    Marini, M; De Niederhausern, S; Iseppi, R; Bondi, M; Sabia, C; Toselli, M; Pilati, F

    2007-04-01

    Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol-gel process. They were applied as a thin layer (0.6-1.1 microm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37 degrees C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features. PMID:17335284

  10. Alkaline phosphatase activity in Zostera noltii hornem. and its contribution to the release of phosphate in the palmones river estuary

    NASA Astrophysics Data System (ADS)

    Hernández, I.; Pérez-Llorens, J. L.; Fernández, J. A.; Niell, F. X.

    Alkaline phosphatase activity (APA) was studied in Zostera noltii Hornem., a sea-grass collected in the Palmones river estuary (southern Spain). The higher activity was found in the leaves, with minor contributions in the stem and the underground parts of the plant. The enzymatic activity showed a two-phase kinetic versus substrate concentration between 5 μM and 25 mM. The influence of some environmental factors important in nature (temperature, pH, salinity, photon irradiance and external phosphate) on the enzymatic activity is discussed. Over an ecophysiological range of these factors, maximum APA was found at 30 0C (22·6 μmol pNP released g dry wt-1 h-1), pH 8·8 (35·6 μmol pNP g dry wt-1 h-1) and salinity 43·8 (27·8 pmol pNP g dry wt-1 h-1). With regard to light, APA and phosphate uptake in shoots were light-saturated and showed similar values for maximum velocity and half-saturation constant. In the range of phosphate concentration tested (0 20 μM), APA was independent of the external phosphate concentration. Finally, as Z. noltii incorporated only 16% of the phosphate hydrolysed from the model phosphomonoester used in the assay, the significance of Z. noltii population in the enzymatic release of phosphate to the estuary was estimated. A minimum of 8·4 nM Pi liberated per day and a maximum of 99·8 nM Pi day-1 was found.