Human-Phosphate-Binding-Protein inhibits HIV-1 gene transcription and replication

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Candolfi Ermanno

2011-07-01

Full Text Available Abstract The Human Phosphate-Binding protein (HPBP is a serendipitously discovered lipoprotein that binds phosphate with high affinity. HPBP belongs to the DING protein family, involved in various biological processes like cell cycle regulation. We report that HPBP inhibits HIV-1 gene transcription and replication in T cell line, primary peripherical blood lymphocytes and primary macrophages. We show that HPBP is efficient in naïve and HIV-1 AZT-resistant strains. Our results revealed HPBP as a new and potent anti HIV molecule that inhibits transcription of the virus, which has not yet been targeted by HAART and therefore opens new strategies in the treatment of HIV infection.

Structural features of PhoX, one of the phosphate-binding proteins from Pho regulon of Xanthomonas citri

Science.gov (United States)

Pegos, Vanessa R.; Santos, Rodrigo M. L.; Medrano, Francisco J.

2017-01-01

In Escherichia coli, the ATP-Binding Cassette transporter for phosphate is encoded by the pstSCAB operon. PstS is the periplasmic component responsible for affinity and specificity of the system and has also been related to a regulatory role and chemotaxis during depletion of phosphate. Xanthomonas citri has two phosphate-binding proteins: PstS and PhoX, which are differentially expressed under phosphate limitation. In this work, we focused on PhoX characterization and comparison with PstS. The PhoX three-dimensional structure was solved in a closed conformation with a phosphate engulfed in the binding site pocket between two domains. Comparison between PhoX and PstS revealed that they originated from gene duplication, but despite their similarities they show significant differences in the region that interacts with the permeases. PMID:28542513

Calcium Alginate and Salt/Phosphate as Binding Agents in Restructured Lamb

OpenAIRE

Setyawardani, Triana; Raharjo, Sri; sudarmadji, purnama

2001-01-01

A study on  restructurization of lamb meat using several binding agents were conducted. Objectives of the study were evaluate  effectivity of Ca–alginate, salt and phosphate as binding agent and their effect on physical properties of the restructured meat stored at -20⁰C for up to 12 weeks. Three binding agents were added to the restructured products, which include NaCl 0.3 %/ NTPP 0.3 %; alginate 0.5 %/Ca-lactate 0.5%; NaCl 0.3 % / NTPP 0.5 %/alginate 0.5% and no binding agent as a control. ...

Aptamer-Conjugated Calcium Phosphate Nanoparticles for Reducing Diabetes Risk via Retinol Binding Protein 4 Inhibition.

Science.gov (United States)

Torabi, Raheleh; Ghourchian, Hedayatollah; Amanlou, Massoud; Pasalar, Parvin

2017-06-01

Inhibition of the binding of retinol to its carrier, retinol binding protein 4, is a new strategy for treating type 2 diabetes; for this purpose, we have provided an aptamer-functionalized multishell calcium phosphate nanoparticle. First, calcium phosphate nanoparticles were synthesized and conjugated to the aptamer. The cytotoxicity of nanoparticles releases the process of aptamer from nanoparticles and their inhibition function of binding retinol to retinol binding protein 4. After synthesizing and characterizing the multishell calcium phosphate nanoparticles and observing the noncytotoxicity of conjugate, the optimum time (48 hours) and the pH (7.4) for releasing the aptamer from the nanoparticles was determined. The half-maximum inhibitory concentration (IC 50 ) value for inhibition of retinol binding to retinol binding protein 4 was 210 femtomolar (fmol). The results revealed that the aptamer could prevent connection between retinol and retinol binding protein 4 at a very low IC 50 value (210 fmol) compared to other reported inhibitors. It seems that this aptamer could be used as an efficient candidate not only for decreasing the insulin resistance in type 2 diabetes, but also for inhibiting the other retinol binding protein 4-related diseases. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

D-Ribulose 5-Phosphate 3-Epimerase: Functional and Structural Relationships to Members of the Ribulose-Phosphate Binding (beta/alpha)8-Barrel Superfamily

International Nuclear Information System (INIS)

Akana, J.; Federov, A.; Federov, E.; Novak, W.; Babbitt, P.; Almo, S.; Gerlt, J.

2006-01-01

The 'ribulose phosphate binding' superfamily defined by the Structural Classification of Proteins (SCOP) database is considered the result of divergent evolution from a common (β/α) 8 -barrel ancestor. The superfamily includes D-ribulose 5-phosphate 3-epimerase (RPE), orotidine 5'-monophosphate decarboxylase (OMPDC), and 3-keto-L-gulonate 6-phosphate decarboxylase (KGPDC), members of the OMPDC suprafamily, as well as enzymes involved in histidine and tryptophan biosynthesis that utilize phosphorylated metabolites as substrates. We now report studies of the functional and structural relationships of RPE to the members of the superfamily. As suggested by the results of crystallographic studies of the RPEs from rice and Plasmodium falciparum, the RPE from Streptococcus pyogenes is activated by Zn 2+ which binds with a stoichiometry of one ion per polypeptide. Although wild type RPE has a high affinity for Zn 2+ and inactive apoenzyme cannot be prepared, the affinity for Zn 2+ is decreased by alanine substitutions for the two histidine residues that coordinate the Zn 2+ ion (H34A and H67A); these mutant proteins can be prepared in an inactive, metal-free form and activated by exogenous Zn 2+ . The crystal structure of the RPE was solved at 1.8 Angstroms resolution in the presence of D-xylitol 5-phosphate, an inert analogue of the D-xylulose 5-phosphate substrate. This structure suggests that the 2,3-enediolate intermediate in the 1,1-proton transfer reaction is stabilized by bidentate coordination to the Zn 2+ that also is liganded to His 34, Asp 36, His 67, and Asp 176; the carboxylate groups of the Asp residues are positioned also to function as the acid/base catalysts. Although the conformation of the bound analogue resembles those of ligands bound in the active sites of OMPDC and KGPDC, the identities of the active site residues that coordinate the essential Zn 2+ and participate as acid/base catalysts are not conserved. We conclude that only the phosphate

D-Ribulose 5-Phosphate 3-Epimerase: Functional and Structural Relationships to Members of the Ribulose-Phosphate Binding (beta/alpha)8-Barrel Superfamily

Energy Technology Data Exchange (ETDEWEB)

Akana,J.; Federov, A.; Federov, E.; Novak, W.; Babbitt, P.; Almo, S.; Gerlt, J.

2006-01-01

The 'ribulose phosphate binding' superfamily defined by the Structural Classification of Proteins (SCOP) database is considered the result of divergent evolution from a common ({beta}/{alpha}){sub 8}-barrel ancestor. The superfamily includes D-ribulose 5-phosphate 3-epimerase (RPE), orotidine 5'-monophosphate decarboxylase (OMPDC), and 3-keto-L-gulonate 6-phosphate decarboxylase (KGPDC), members of the OMPDC suprafamily, as well as enzymes involved in histidine and tryptophan biosynthesis that utilize phosphorylated metabolites as substrates. We now report studies of the functional and structural relationships of RPE to the members of the superfamily. As suggested by the results of crystallographic studies of the RPEs from rice and Plasmodium falciparum, the RPE from Streptococcus pyogenes is activated by Zn{sup 2+} which binds with a stoichiometry of one ion per polypeptide. Although wild type RPE has a high affinity for Zn{sup 2+} and inactive apoenzyme cannot be prepared, the affinity for Zn{sup 2+} is decreased by alanine substitutions for the two histidine residues that coordinate the Zn{sup 2+} ion (H34A and H67A); these mutant proteins can be prepared in an inactive, metal-free form and activated by exogenous Zn{sup 2+}. The crystal structure of the RPE was solved at 1.8 Angstroms resolution in the presence of D-xylitol 5-phosphate, an inert analogue of the D-xylulose 5-phosphate substrate. This structure suggests that the 2,3-enediolate intermediate in the 1,1-proton transfer reaction is stabilized by bidentate coordination to the Zn{sup 2+} that also is liganded to His 34, Asp 36, His 67, and Asp 176; the carboxylate groups of the Asp residues are positioned also to function as the acid/base catalysts. Although the conformation of the bound analogue resembles those of ligands bound in the active sites of OMPDC and KGPDC, the identities of the active site residues that coordinate the essential Zn{sup 2+} and participate as acid/base catalysts

Automated identification of protein-ligand interaction features using Inductive Logic Programming: a hexose binding case study.

Science.gov (United States)

A Santos, Jose C; Nassif, Houssam; Page, David; Muggleton, Stephen H; E Sternberg, Michael J

2012-07-11

There is a need for automated methods to learn general features of the interactions of a ligand class with its diverse set of protein receptors. An appropriate machine learning approach is Inductive Logic Programming (ILP), which automatically generates comprehensible rules in addition to prediction. The development of ILP systems which can learn rules of the complexity required for studies on protein structure remains a challenge. In this work we use a new ILP system, ProGolem, and demonstrate its performance on learning features of hexose-protein interactions. The rules induced by ProGolem detect interactions mediated by aromatics and by planar-polar residues, in addition to less common features such as the aromatic sandwich. The rules also reveal a previously unreported dependency for residues cys and leu. They also specify interactions involving aromatic and hydrogen bonding residues. This paper shows that Inductive Logic Programming implemented in ProGolem can derive rules giving structural features of protein/ligand interactions. Several of these rules are consistent with descriptions in the literature. In addition to confirming literature results, ProGolem's model has a 10-fold cross-validated predictive accuracy that is superior, at the 95% confidence level, to another ILP system previously used to study protein/hexose interactions and is comparable with state-of-the-art statistical learners.

Evaluation of intestinal phosphate binding to improve the safety profile of oral sodium phosphate bowel cleansing.

Directory of Open Access Journals (Sweden)

Stef Robijn

Full Text Available Prior to colonoscopy, bowel cleansing is performed for which frequently oral sodium phosphate (OSP is used. OSP results in significant hyperphosphatemia and cases of acute kidney injury (AKI referred to as acute phosphate nephropathy (APN; characterized by nephrocalcinosis are reported after OSP use, which led to a US-FDA warning. To improve the safety profile of OSP, it was evaluated whether the side-effects of OSP could be prevented with intestinal phosphate binders. Hereto a Wistar rat model of APN was developed. OSP administration (2 times 1.2 g phosphate by gavage with a 12h time interval induced bowel cleansing (severe diarrhea and significant hyperphosphatemia (21.79 ± 5.07 mg/dl 6h after the second OSP dose versus 8.44 ± 0.97 mg/dl at baseline. Concomitantly, serum PTH levels increased fivefold and FGF-23 levels showed a threefold increase, while serum calcium levels significantly decreased from 11.29 ± 0.53 mg/dl at baseline to 8.68 ± 0.79 mg/dl after OSP. OSP administration induced weaker NaPi-2a staining along the apical proximal tubular membrane. APN was induced: serum creatinine increased (1.5 times baseline and nephrocalcinosis developed (increased renal calcium and phosphate content and calcium phosphate deposits on Von Kossa stained kidney sections. Intestinal phosphate binding (lanthanum carbonate or aluminum hydroxide was not able to attenuate the OSP induced side-effects. In conclusion, a clinically relevant rat model of APN was developed. Animals showed increased serum phosphate levels similar to those reported in humans and developed APN. No evidence was found for an improved safety profile of OSP by using intestinal phosphate binders.

Further investigations on the inorganic phosphate binding site of beef heart mitochondrial F1-ATPase

International Nuclear Information System (INIS)

Pougeois, R.; Lauquin, G.J.

1985-01-01

The possibility that 4-azido-2-nitrophenyl phosphate (ANPP), a photoreactive derivative of inorganic phosphate (P /sub i/ ), could mimic ATP was investigated. ANPP was hydrolyzed in the dark by sarcoplasmic reticulum Ca 2+ -ATPase in the presence of Ca 2+ but not in the presence of ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. ANPP was not hydrolyzed by purified mitochondrial F1-ATPase; however, ADP and ATP protected F1-ATPase against ANPP photoinactivation. On the other hand, the trinitrophenyl nucleotide analogues (TNP-ADP, TNP-ATP, and TNP-AMP-PNP), which bind specifically at the two catalytic sites of F1-ATPase, abolished P /sub i/ binding on F1-ATPase; they do not protect F1-ATPase against ANPP photoinactivation. Furthermore, ANPP-photoinactivated F1-ATPase binds the TNP analogues in the same way as the native enzyme. The Pi binding site of F1-ATPase, which is shown to be photolabeled by ANPP, does not appear to be at the gamma-phosphate position of the catalytic sites

Vitamin B12 Phosphate Conjugation and Its Effect on Binding to the Human B12 -Binding Proteins Intrinsic Factor and Haptocorrin

DEFF Research Database (Denmark)

Ó Proinsias, Keith; Ociepa, Michał; Pluta, Katarzyna

2016-01-01

The binding of vitamin B12 derivatives to human B12 transporter proteins is strongly influenced by the type and site of modification of the cobalamin original structure. We have prepared the first cobalamin derivative modified at the phosphate moiety. The reaction conditions were fully optimized...... and its limitations examined. The resulting derivatives, particularly those bearing terminal alkyne and azide groups, were isolated and used in copper-catalyzed alkyne-azide cycloaddition reactions (CuAAC). Their sensitivity towards light revealed their potential as photocleavable molecules. The binding...... abilities of selected derivatives were examined and compared with cyanocobalamin. The interaction of the alkylated derivatives with haptocorrin was less affected than the interaction with intrinsic factor. Furthermore, the configuration of the phosphate moiety was irrelevant to the binding process....

Automated identification of protein-ligand interaction features using Inductive Logic Programming: a hexose binding case study

Directory of Open Access Journals (Sweden)

A Santos Jose C

2012-07-01

Full Text Available Abstract Background There is a need for automated methods to learn general features of the interactions of a ligand class with its diverse set of protein receptors. An appropriate machine learning approach is Inductive Logic Programming (ILP, which automatically generates comprehensible rules in addition to prediction. The development of ILP systems which can learn rules of the complexity required for studies on protein structure remains a challenge. In this work we use a new ILP system, ProGolem, and demonstrate its performance on learning features of hexose-protein interactions. Results The rules induced by ProGolem detect interactions mediated by aromatics and by planar-polar residues, in addition to less common features such as the aromatic sandwich. The rules also reveal a previously unreported dependency for residues cys and leu. They also specify interactions involving aromatic and hydrogen bonding residues. This paper shows that Inductive Logic Programming implemented in ProGolem can derive rules giving structural features of protein/ligand interactions. Several of these rules are consistent with descriptions in the literature. Conclusions In addition to confirming literature results, ProGolem’s model has a 10-fold cross-validated predictive accuracy that is superior, at the 95% confidence level, to another ILP system previously used to study protein/hexose interactions and is comparable with state-of-the-art statistical learners.

Complete Hexose Isomer Identification with Mass Spectrometry

Science.gov (United States)

Nagy, Gabe; Pohl, Nicola L. B.

2015-04-01

The first analytical method is presented for the identification and absolute configuration determination of all 24 aldohexose and 2-ketohexose isomers, including the D and L enantiomers for allose, altrose, galactose, glucose, gulose, idose, mannose, talose, fructose, psicose, sorbose, and tagatose. Two unique fixed ligand kinetic method combinations were discovered to create significant enough energetic differences to achieve chiral discrimination among all 24 hexoses. Each of these 24 hexoses yields unique ratios of a specific pair of fragment ions that allows for simultaneous determination of identification and absolute configuration. This mass spectrometric-based methodology can be readily employed for accurate identification of any isolated monosaccharide from an unknown biological source. This work provides a key step towards the goal of complete de novo carbohydrate analysis.

Critical role of γ-phosphate in structural transition of Na,K-ATPase upon ATP binding

Science.gov (United States)

Petrushanko, Irina Yu.; Mitkevich, Vladimir A.; Anashkina, Anastasia A.; Klimanova, Elizaveta A.; Dergousova, Elena A.; Lopina, Olga D.; Makarov, Alexander A.

2014-06-01

Active transport of sodium and potassium ions by Na,K-ATPase is accompanied by the enzyme conformational transition between E1 and E2 states. ATP and ADP bind to Na,K-ATPase in the E1 conformation with similar affinity but the properties of enzyme in complexes with these nucleotides are different. We have studied thermodynamics of Na,K-ATPase binding with adenine nucleotides at different temperatures using isothermal titration calorimetry. Our data indicate that β-phosphate is involved in complex formation by increasing the affinity of adenine nucleotides to Na,K-ATPase by an order of magnitude, while γ-phosphate does not affect it. ATP binding to Na,K-ATPase in contrast to ADP binding generates a structural transition in the enzyme, which is consistent with the movement of a significant portion of the surface area to a solvent-protected state. We propose that ATP binding leads to convergence of the nucleotide-binding and phosphorylation domains transferring the enzyme from the ``E1-open'' to ``E1-closed'' conformation ready for phosphorylation.

Phosphate binding therapy in dialysis patients: focus on lanthanum carbonate

Directory of Open Access Journals (Sweden)

Ismail A Mohammed

2008-11-01

carbonate, dialysis, phosphate binding

Gastric emptying of hexose sugars: role of osmolality, molecular structure and the CCK₁ receptor.

Science.gov (United States)

Little, T J; Gopinath, A; Patel, E; McGlone, A; Lassman, D J; D'Amato, M; McLaughlin, J T; Thompson, D G

2010-11-01

It is widely reported that hexose sugars slow gastric emptying (GE) via osmoreceptor stimulation but this remains uncertain. We evaluated the effects of a panel of hexoses of differing molecular structure, assessing the effects of osmolality, intra-individual reproducibility and the role of the CCK(1) receptor, in the regulation of GE by hexoses. Thirty one healthy non-obese male and female subjects were studied in a series of protocols, using a (13) C-acetate breath test to evaluate GE of varying concentrations of glucose, galactose, fructose and tagatose, with water, NaCl and lactulose as controls. GE was further evaluated following the administration of a CCK(1) receptor antagonist. Three subjects underwent repeated studies to evaluate intra-individual reproducibility. At 250 mOsmol, a hexose-specific effect was apparent: tagatose slowed GE more potently than water, glucose and fructose (P effects of hexose sugars on GE appear related to their molecular structure rather than osmolality per se, and are, at least in part, CCK(1) receptor-dependent. © 2010 Blackwell Publishing Ltd.

Measurement of binding of adenine nucleotides and phosphate to cytosolic proteins in permeabilized rat-liver cells

NARCIS (Netherlands)

Gankema, H. S.; Groen, A. K.; Wanders, R. J.; Tager, J. M.

1983-01-01

1. A method is described for measuring the binding of metabolites to cytosolic proteins in situ in isolated rat-liver cells treated with filipin to render the plasma membrane permeable to compounds of low molecular weight. 2. There is no binding of ATP or inorganic phosphate to cytosolic proteins,

Quantifying the Contribution of Grape Hexoses to Wine Volatiles by High-Precision [U13C]-Glucose Tracer Studies

Science.gov (United States)

Nisbet, Mark A.; Tobias, Herbert J.; Brenna, J. Thomas; Sacks, Gavin L.; Mansfield, Anna Katharine

2016-01-01

Many fermentation volatiles important to wine aroma potentially arise from yeast metabolism of hexose sugars, but assessing the relative importance of these pathways is challenging due to high endogenous hexose substrate concentrations. To overcome this problem, gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) was used to measure high-precision 13C/12C isotope ratios of volatiles in wines produced from juices spiked with tracer levels (0.01–1 APE) of uniformly labeled [U-13C]-glucose. The contribution of hexose to individual volatiles was determined from the degree of 13C enrichment. As expected, straight-chain fatty acids and their corresponding ethyl esters were derived almost exclusively from hexoses. Most fusel alcohols and their acetate esters were also majority hexose-derived, indicating the importance of anabolic pathways for their formation. Only two compounds were not derived primarily from hexoses (hexanol and isobutyric acid). This approach can be extended to other food systems or substrates for studying precursor–product relationships. PMID:24960193

Quantifying the contribution of grape hexoses to wine volatiles by high-precision [U¹³C]-glucose tracer studies.

Science.gov (United States)

Nisbet, Mark A; Tobias, Herbert J; Brenna, J Thomas; Sacks, Gavin L; Mansfield, Anna Katharine

2014-07-16

Many fermentation volatiles important to wine aroma potentially arise from yeast metabolism of hexose sugars, but assessing the relative importance of these pathways is challenging due to high endogenous hexose substrate concentrations. To overcome this problem, gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) was used to measure high-precision (13)C/(12)C isotope ratios of volatiles in wines produced from juices spiked with tracer levels (0.01-1 APE) of uniformly labeled [U-(13)C]-glucose. The contribution of hexose to individual volatiles was determined from the degree of (13)C enrichment. As expected, straight-chain fatty acids and their corresponding ethyl esters were derived almost exclusively from hexoses. Most fusel alcohols and their acetate esters were also majority hexose-derived, indicating the importance of anabolic pathways for their formation. Only two compounds were not derived primarily from hexoses (hexanol and isobutyric acid). This approach can be extended to other food systems or substrates for studying precursor-product relationships.

Uptake of 13C-glucose by cell suspensions of carrot (Daucus carota) measured by in vivo NMR: Cycling of triose, pentose- and hexose-phosphates

NARCIS (Netherlands)

Krook, J.; Vreugdenhil, D.; Dijkema, C.; Plas, van der L.H.W.

2000-01-01

After a lag phase of 2 days, batch-grown cells of carrot (Daucus carota L.) cv. Flakkese entered the exponential growth phase and started to accumulate sucrose and hexoses. Short-term feeding 13C-glucose in this period resulted in only minor labelling of sucrose or fructose. CO2 production from

Assessment of phosphate binding by sevelamer carbonate powder for oral suspension mixed in foods.

Science.gov (United States)

Hanus, Martin; Zhorov, Eugene; Brommage, Deborah; Plone, Melissa; Holmes-Farley, Stephen Randall

2012-01-01

This study investigated mixing sevelamer carbonate powder with foods and beverages other than water. Food samples, including applesauce, oatmeal, chicken, protein powder, scrambled eggs, ginger ale, and diet ginger ale, were subjected to an in vitro assay, and the difference in the amount of phosphate bound between samples pre-exposed to foods and samples where the drug was exposed to foods concurrently was determined Under these assay conditions, pre-exposure to sevelamer carbonate powder had no effect on the ability to bind phosphate. Clinical testing is needed to further evaluate this finding.

Discovery of a novel glucose metabolism in cancer: The role of endoplasmic reticulum beyond glycolysis and pentose phosphate shunt

Science.gov (United States)

Marini, Cecilia; Ravera, Silvia; Buschiazzo, Ambra; Bianchi, Giovanna; Orengo, Anna Maria; Bruno, Silvia; Bottoni, Gianluca; Emionite, Laura; Pastorino, Fabio; Monteverde, Elena; Garaboldi, Lucia; Martella, Roberto; Salani, Barbara; Maggi, Davide; Ponzoni, Mirco; Fais, Franco; Raffaghello, Lizzia; Sambuceti, Gianmario

2016-01-01

Cancer metabolism is characterized by an accelerated glycolytic rate facing reduced activity of oxidative phosphorylation. This “Warburg effect” represents a standard to diagnose and monitor tumor aggressiveness with 18F-fluorodeoxyglucose whose uptake is currently regarded as an accurate index of total glucose consumption. Studying cancer metabolic response to respiratory chain inhibition by metformin, we repeatedly observed a reduction of tracer uptake facing a marked increase in glucose consumption. This puzzling discordance brought us to discover that 18F-fluorodeoxyglucose preferentially accumulates within endoplasmic reticulum by exploiting the catalytic function of hexose-6-phosphate-dehydrogenase. Silencing enzyme expression and activity decreased both tracer uptake and glucose consumption, caused severe energy depletion and decreased NADPH content without altering mitochondrial function. These data document the existence of an unknown glucose metabolism triggered by hexose-6-phosphate-dehydrogenase within endoplasmic reticulum of cancer cells. Besides its basic relevance, this finding can improve clinical cancer diagnosis and might represent potential target for therapy. PMID:27121192

Calcium Alginate and Salt/Phosphate as Binding Agents in Restructured Lamb

Directory of Open Access Journals (Sweden)

Triana Setyawardani

2001-01-01

Full Text Available A study on restructurization of lamb meat using several binding agents were conducted. Objectives of the study were evaluate effectivity of Ca–alginate, salt and phosphate as binding agent and their effect on physical properties of the restructured meat stored at -20⁰C for up to 12 weeks. Three binding agents were added to the restructured products, which include NaCl 0.3 %/ NTPP 0.3 %; alginate 0.5 %/Ca-lactate 0.5%; NaCl 0.3 % / NTPP 0.5 %/alginate 0.5% and no binding agent as a control. The products were evaluated at 0, 4, 8 and 12 weeks of storage. The result showed that treatment with alginate 0.5%/Ca-lactate 0.5% had the least purge loss value of 4.3±0.2%. The least cooking losses of 30.2±3.79% and the highest shear force 61.6±13.77 N. (Animal Production 3(1: 20-25 (2001Key Words: Alginate/Ca-lactate, purge loss, cooking losses, shear force.

Calcium Alginate and Salt/Phosphate as Binding Agents in Restructured Lamb

Directory of Open Access Journals (Sweden)

Triana Setyawardani

2001-01-01

Full Text Available A study on  restructurization of lamb meat using several binding agents were conducted. Objectives of the study were evaluate  effectivity of Ca–alginate, salt and phosphate as binding agent and their effect on physical properties of the restructured meat stored at -20⁰C for up to 12 weeks. Three binding agents were added to the restructured products, which include NaCl 0.3 %/ NTPP 0.3 %; alginate 0.5 %/Ca-lactate 0.5%; NaCl 0.3 % / NTPP 0.5 %/alginate 0.5% and no binding agent as a control. The products were evaluated at 0, 4, 8 and 12 weeks of storage. The result showed that treatment with alginate 0.5%/Ca-lactate 0.5% had the least purge loss value of 4.3±0.2%. The least cooking losses of 30.2±3.79% and the highest shear force 61.6±13.77 N. (Animal Production 3(1: 20-25 (2001 Key Words: Alginate/Ca-lactate, purge loss, cooking losses, shear  force.

Detection of mono- and di-hexoses as metabolites of 4-bromoaniline using HPLC-TOF-MS/MS.

Science.gov (United States)

Major, H; Castro-Perez, J; Nicholson, J K; Wilson, I D

2003-08-01

1. The metabolic fate of 4-bromoaniline (4-BrA) was investigated in rat following intraperitoneal administration at 50 mg kg(-1) using HPLC-TOF-MS/MS. 2. The sensitivity provided by the use of TOF-MS/MS, aided by the distinctive isotope pattern resulting from the presence of the bromine substituent in the molecule, enabled the detection of many previously uncharacterized metabolites in the samples. 3. Several groups of minor metabolites were detected in the urine that corresponded to a number of isomeric hexose and di-hexose-containing conjugates (possibly glucosides and diglucosides) of 4-BrA. 4. As well as hexose and di-hexose conjugates of 4-BrA, several further groups of metabolites that also contained either a sulphamate or sulphate group in addition to the sugar moieties were also detected.

Binding and uptake of {sup 125}iodine-labelled, oxidized low density lipoprotein by macrophages: Comparison of the effects of {alpha}-tocopherol, probucol, pyridoxal-5`-phosphate and magnesium-pyridoxal-5`-phosphate-glutamate

Energy Technology Data Exchange (ETDEWEB)

Selmer, D. [Technische Univ. Muenchen, Freising-Weihenstephan (Germany). Lehrstuhl fuer Phytopathologie; Senekowitsch-Schmidtke, R. [Technische Univ. Muenchen (Germany). Nuklearmedizinische Klinik; Schneider, W. [Steigerwald Arzneimittel, Darmstadt (Germany); Elstner, E.F. [Technische Univ. Muenchen, Freising-Weihenstephan (Germany). Lehrstuhl fuer Phytopathologie

1997-01-01

Specific and unspecific binding and uptake (internalization) by macrophages of {sup 125}iodine-labelled, copper-oxidized human low density lipoprotein is differently influenced by the anti-oxidants {alpha}-tocopherol ({alpha}-Toc), probucol (Prob), pyridoxal-5`-phosphate (PP) and the magnesium-pyridoxal-5`-phosphate glutamate complex (MPPG). Binding as well as internalization, mediated by the so-called `scavenger receptor` is lower in the presence of MPPG whereas both specific binding and internalization are enhanced. The comparison of the effects in vitro allows a rating of the potentially anti-atherogenic and thus protective effects of the tested substances as follows: MPPG>PP>{alpha}-Toc>Prob. (orig.)

Effects of topical application of aqueous solutions of hexoses on epidermal permeability barrier recovery rate after barrier disruption.

Science.gov (United States)

Denda, Mitsuhiro

2011-11-01

Previous studies have suggested that hexose molecules influence the stability of phospholipid bilayers. Therefore, the effects of topical application of all 12 stereoisomers of dextro-hexose on the epidermal barrier recovery rate after barrier disruption were evaluated. Immediately after tape stripping, 0.1 m aqueous solution of each hexose was applied on hairless mouse skin. Among the eight dextro-aldohexoses, topical application of altose, idose, mannose and talose accelerated the barrier recovery, while allose, galactose, glucose and gulose had no effect. Among the four dextro-ketohexoses, psicose, fructose, sorbose and tagatose all accelerated the barrier recovery. As the effects of hexoses on the barrier recovery rate appeared within 1 h, the mechanism is unlikely to be genomic. Instead, these hexoses may influence phase transition of the lipid bilayers of lamellar bodies and cell membrane, a crucial step in epidermal permeability barrier homeostasis. © 2011 John Wiley & Sons A/S.

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

International Nuclear Information System (INIS)

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.

Quantification of total hexose on dry blood spot by tandem mass spectrometry.

Science.gov (United States)

Gong, Zhenhua; Tian, Guoli; Huang, Qiwei; Wang, Yanmin; Ge, Qingwei

2012-12-01

Because hypoglycemia and hyperglycemia are harmful and not always associated with overt clinical signs, it is necessary to have methods available to screen for glucose levels to detect hypoglycemia and diabetes as early as possible. A new method for such screening and the clinical determination of blood total hexose on a dry blood spot (DBS) using tandem mass spectrometry (MS/MS) was developed. The serum glucose controls and blood were prepared as DBS and then extracted into a methanol solution containing isotope-labeled internal standards. The methanolic extraction was subjected to HPLC, followed by MS/MS in positive ion mode. Multiple-reaction monitoring of m/z 203.1→23 was used to detect hexose, and m/z 209.0→23 was used for 13C6-D-glucose. The recoveries of blood glucose by MS/MS were 90%-102% with an R(2) value of 0.999 after linear regression (pblood total hexose in neonates aged 3-7 days (6.41±1.46 mmol/L) was lower than that in neonates aged 8-30 days (6.66±1.38 mmol/L), and it was lower in neonates than in children aged 1-72 months (7.19±1.87 mmol/L). Quantification of total hexose on a dry blood spot by MS/MS is accurate, reliable and feasible for screening and clinical tests. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Functional consequences of piceatannol binding to glyceraldehyde-3-phosphate dehydrogenase.

Science.gov (United States)

Gerszon, Joanna; Serafin, Eligiusz; Buczkowski, Adam; Michlewska, Sylwia; Bielnicki, Jakub Antoni; Rodacka, Aleksandra

2018-01-01

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is one of the key redox-sensitive proteins whose activity is largely affected by oxidative modifications at its highly reactive cysteine residue in the enzyme's active site (Cys149). Prolonged exposure to oxidative stress may cause, inter alia, the formation of intermolecular disulfide bonds leading to accumulation of GAPDH aggregates and ultimately to cell death. Recently these anomalies have been linked with the pathogenesis of Alzheimer's disease. Novel evidences indicate that low molecular compounds may be effective inhibitors potentially preventing the GAPDH translocation to the nucleus, and inhibiting or slowing down its aggregation and oligomerization. Therefore, we decided to establish the ability of naturally occurring compound, piceatannol, to interact with GAPDH and to reveal its effect on functional properties and selected parameters of the dehydrogenase structure. The obtained data revealed that piceatannol binds to GAPDH. The ITC analysis indicated that one molecule of the tetrameric enzyme may bind up to 8 molecules of polyphenol (7.3 ± 0.9). Potential binding sites of piceatannol to the GAPDH molecule were analyzed using the Ligand Fit algorithm. Conducted analysis detected 11 ligand binding positions. We indicated that piceatannol decreases GAPDH activity. Detailed analysis allowed us to presume that this effect is due to piceatannol ability to assemble a covalent binding with nucleophilic cysteine residue (Cys149) which is directly involved in the catalytic reaction. Consequently, our studies strongly indicate that piceatannol would be an exceptional inhibitor thanks to its ability to break the aforementioned pathologic disulfide linkage, and therefore to inhibit GAPDH aggregation. We demonstrated that by binding with GAPDH piceatannol blocks cysteine residue and counteracts its oxidative modifications, that induce oligomerization and GAPDH aggregation.

Kinetics and mechanism of thermal degradation of pentose- and hexose-based carbohydrate polymers.

Science.gov (United States)

Akbar, Jamshed; Iqbal, Mohammad S; Massey, Shazma; Masih, Rashid

2012-10-15

This work aims at study of thermal degradation kinetics and mechanism of pentose- and hexose-based carbohydrate polymers isolated from Plantago ovata (PO), Salvia aegyptiaca (SA) and Ocimum basilicum (OB). The analysis was performed by isoconversional method. The materials exhibited mainly two-stage degradation. The weight loss at ambient-115°C characterized by low activation energy corresponds to loss of moisture. The kinetic triplets consisting of E, A and g(α) model of the materials were determined. The major degradation stage represents a loss of high boiling volatile components. This stage is exothermic in nature. Above 340°C complete degradation takes place leaving a residue of 10-15%. The master plots of g(α) function clearly differentiated the degradation mechanism of hexose-based OB and SA polymers and pentose-based PO polymer. The pentose-based carbohydrate polymer showed D(4) type and the hexose-based polymers showed A(4) type degradation mechanism. Copyright © 2012 Elsevier Ltd. All rights reserved.

Functional consequences of piceatannol binding to glyceraldehyde-3-phosphate dehydrogenase.

Directory of Open Access Journals (Sweden)

Joanna Gerszon

Full Text Available Glyceraldehyde-3-phosphate dehydrogenase (GAPDH is one of the key redox-sensitive proteins whose activity is largely affected by oxidative modifications at its highly reactive cysteine residue in the enzyme's active site (Cys149. Prolonged exposure to oxidative stress may cause, inter alia, the formation of intermolecular disulfide bonds leading to accumulation of GAPDH aggregates and ultimately to cell death. Recently these anomalies have been linked with the pathogenesis of Alzheimer's disease. Novel evidences indicate that low molecular compounds may be effective inhibitors potentially preventing the GAPDH translocation to the nucleus, and inhibiting or slowing down its aggregation and oligomerization. Therefore, we decided to establish the ability of naturally occurring compound, piceatannol, to interact with GAPDH and to reveal its effect on functional properties and selected parameters of the dehydrogenase structure. The obtained data revealed that piceatannol binds to GAPDH. The ITC analysis indicated that one molecule of the tetrameric enzyme may bind up to 8 molecules of polyphenol (7.3 ± 0.9. Potential binding sites of piceatannol to the GAPDH molecule were analyzed using the Ligand Fit algorithm. Conducted analysis detected 11 ligand binding positions. We indicated that piceatannol decreases GAPDH activity. Detailed analysis allowed us to presume that this effect is due to piceatannol ability to assemble a covalent binding with nucleophilic cysteine residue (Cys149 which is directly involved in the catalytic reaction. Consequently, our studies strongly indicate that piceatannol would be an exceptional inhibitor thanks to its ability to break the aforementioned pathologic disulfide linkage, and therefore to inhibit GAPDH aggregation. We demonstrated that by binding with GAPDH piceatannol blocks cysteine residue and counteracts its oxidative modifications, that induce oligomerization and GAPDH aggregation.

Comparison of S. cerevisiae F-BAR domain structures reveals a conserved inositol phosphate binding site

Science.gov (United States)

Moravcevic, Katarina; Alvarado, Diego; Schmitz, Karl R.; Kenniston, Jon A.; Mendrola, Jeannine M.; Ferguson, Kathryn M.; Lemmon, Mark A.

2015-01-01

SUMMARY F-BAR domains control membrane interactions in endocytosis, cytokinesis, and cell signaling. Although generally thought to bind curved membranes containing negatively charged phospholipids, numerous functional studies argue that differences in lipid-binding selectivities of F-BAR domains are functionally important. Here, we compare membrane-binding properties of the S. cerevisiae F-BAR domains in vitro and in vivo. Whereas some F-BAR domains (such as Bzz1p and Hof1p F-BARs) bind equally well to all phospholipids, the F-BAR domain from the RhoGAP Rgd1p preferentially binds phosphoinositides. We determined X-ray crystal structures of F-BAR domains from Hof1p and Rgd1p, the latter bound to an inositol phosphate. The structures explain phospholipid-binding selectivity differences, and reveal an F-BAR phosphoinositide binding site that is fully conserved in a mammalian RhoGAP called Gmip, and is partly retained in certain other F-BAR domains. Our findings reveal previously unappreciated determinants of F-BAR domain lipid-binding specificity, and provide a basis for its prediction from sequence. PMID:25620000

Rheb Protein Binds CAD (Carbamoyl-phosphate Synthetase 2, Aspartate Transcarbamoylase, and Dihydroorotase) Protein in a GTP- and Effector Domain-dependent Manner and Influences Its Cellular Localization and Carbamoyl-phosphate Synthetase (CPSase) Activity*

Science.gov (United States)

Sato, Tatsuhiro; Akasu, Hitomi; Shimono, Wataru; Matsu, Chisa; Fujiwara, Yuki; Shibagaki, Yoshio; Heard, Jeffrey J.; Tamanoi, Fuyuhiko; Hattori, Seisuke

2015-01-01

Rheb small GTPases, which consist of Rheb1 and Rheb2 (also known as RhebL1) in mammalian cells, are unique members of the Ras superfamily and play central roles in regulating protein synthesis and cell growth by activating mTOR. To gain further insight into the function of Rheb, we carried out a search for Rheb-binding proteins and found that Rheb binds to CAD protein (carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase), a multifunctional enzyme required for the de novo synthesis of pyrimidine nucleotides. CAD binding is more pronounced with Rheb2 than with Rheb1. Rheb binds CAD in a GTP- and effector domain-dependent manner. The region of CAD where Rheb binds is located at the C-terminal region of the carbamoyl-phosphate synthetase domain and not in the dihydroorotase and aspartate transcarbamoylase domains. Rheb stimulated carbamoyl-phosphate synthetase activity of CAD in vitro. In addition, an elevated level of intracellular UTP pyrimidine nucleotide was observed in Tsc2-deficient cells, which was attenuated by knocking down of Rheb. Immunostaining analysis showed that expression of Rheb leads to increased accumulation of CAD on lysosomes. Both a farnesyltransferase inhibitor that blocks membrane association of Rheb and knockdown of Rheb mislocalized CAD. These results establish CAD as a downstream effector of Rheb and suggest a possible role of Rheb in regulating de novo pyrimidine nucleotide synthesis. PMID:25422319

Rheb protein binds CAD (carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase) protein in a GTP- and effector domain-dependent manner and influences its cellular localization and carbamoyl-phosphate synthetase (CPSase) activity.

Science.gov (United States)

Sato, Tatsuhiro; Akasu, Hitomi; Shimono, Wataru; Matsu, Chisa; Fujiwara, Yuki; Shibagaki, Yoshio; Heard, Jeffrey J; Tamanoi, Fuyuhiko; Hattori, Seisuke

2015-01-09

Rheb small GTPases, which consist of Rheb1 and Rheb2 (also known as RhebL1) in mammalian cells, are unique members of the Ras superfamily and play central roles in regulating protein synthesis and cell growth by activating mTOR. To gain further insight into the function of Rheb, we carried out a search for Rheb-binding proteins and found that Rheb binds to CAD protein (carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase), a multifunctional enzyme required for the de novo synthesis of pyrimidine nucleotides. CAD binding is more pronounced with Rheb2 than with Rheb1. Rheb binds CAD in a GTP- and effector domain-dependent manner. The region of CAD where Rheb binds is located at the C-terminal region of the carbamoyl-phosphate synthetase domain and not in the dihydroorotase and aspartate transcarbamoylase domains. Rheb stimulated carbamoyl-phosphate synthetase activity of CAD in vitro. In addition, an elevated level of intracellular UTP pyrimidine nucleotide was observed in Tsc2-deficient cells, which was attenuated by knocking down of Rheb. Immunostaining analysis showed that expression of Rheb leads to increased accumulation of CAD on lysosomes. Both a farnesyltransferase inhibitor that blocks membrane association of Rheb and knockdown of Rheb mislocalized CAD. These results establish CAD as a downstream effector of Rheb and suggest a possible role of Rheb in regulating de novo pyrimidine nucleotide synthesis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

In vitro incorporation of 14C-hexose-6-phosphat in mannan, β-glucan and glycogen of Candida spec. H and their mutants

International Nuclear Information System (INIS)

Roeber, B.; Reuter, G.

1982-01-01

Mannose-6-P is an activator of 14 C-mannose incorporation from GDP- 14 C-mannose in mono- and oligosaccharides and in mannopolymers of the cell wall proteophosphomannan produced by the food protein yeast Candida spec. H. Moreover, mannose-6-P is a precursor of proteophosphomannan: 14 C-mannose-6-P has been incorporated in absence of GTP. Corresponding behavior shows glucose-6-P by synthesis of β-glucan and glycogen. Mutants of Candida spec. H with different efficiency in the biosynthesis of mannan, β-glucan and glycogen incorporate hexose-6-P in a different extent. (author)

Kinetics and thermodynamics of the binding of riboflavin, riboflavin 5'-phosphate and riboflavin 3',5'-bisphosphate by apoflavodoxins.

OpenAIRE

Pueyo, J J; Curley, G P; Mayhew, S G

1996-01-01

The reactions of excess apoflavodoxin from Desulfovibrio vulgaris, Anabaena variabilis and Azotobacter vinelandii with ribo- flavin 5«-phosphate (FMN), riboflavin 3«,5«-bisphosphate and riboflavin are pseudo-first-order. The rates increase with decreasing pH in the range pH 5-8, and, in general, they increase with increasing ionic strength to approach a maximum at an ionic strength greater than 0.4 M. The rate of FMN binding in phosphate at high pH increases to a maximum ...

Concerted regulation of npc2 binding to endosomal/lysosomal membranes by bis(monoacylglycero)phosphate and sphingomyelin

DEFF Research Database (Denmark)

Enkavi, Giray; Mikkolainen, Heikki; Güngör, Burçin

2017-01-01

remained elusive. Here, based on an extensive set of atomistic simulations and free energy calculations, we clarify the mechanism and energetics of npc2-membrane binding and characterize the roles of physiologically relevant key lipids associated with the binding process. Our results capture in atomistic......Niemann-Pick Protein C2 (npc2) is a small soluble protein critical for cholesterol transport within and from the lysosome and the late endosome. Intriguingly, npc2-mediated cholesterol transport has been shown to be modulated by lipids, yet the molecular mechanism of npc2-membrane interactions has......). This mode is associated with cholesterol uptake and release. On the other hand, the second mode (Supine) places the cholesterol binding pocket away from the membrane surface, but has overall higher membrane binding affinity. We determined that bis(monoacylglycero)phosphate (bmp) is specifically required...

Binding of Diphtheria Toxin to Phospholipids in Liposomes

Science.gov (United States)

Alving, Carl R.; Iglewski, Barbara H.; Urban, Katharine A.; Moss, Joel; Richards, Roberta L.; Sadoff, Jerald C.

1980-04-01

Diphtheria toxin bound to the phosphate portion of some, but not all, phospholipids in liposomes. Liposomes consisting of dimyristoyl phosphatidylcholine and cholesterol did not bind toxin. Addition of 20 mol% (compared to dimyristoyl phosphatidylcholine) of dipalmitoyl phosphatidic acid, dicetyl phosphate, phosphatidylinositol phosphate, cardiolipin, or phosphatidylserine in the liposomes resulted in substantial binding of toxin. Inclusion of phosphatidylinositol in dimyristol phosphatidylcholine / cholesterol liposomes did not result in toxin binding. The calcium salt of dipalmitoyl phosphatidic acid was more effective than the sodium salt, and the highest level of binding occurred with liposomes consisting only of dipalmitoyl phosphatidic acid (calcium salt) and cholesterol. Binding of toxin to liposomes was dependent on pH, and the pattern of pH dependence varied with liposomes having different compositions. Incubation of diphtheria toxin with liposomes containing dicetyl phosphate resulted in maximal binding at pH 3.6, whereas binding to liposomes containing phosphatidylinositol phosphate was maximal above pH 7. Toxin did not bind to liposomes containing 20 mol% of a free fatty acid (palmitic acid) or a sulfated lipid (3-sulfogalactosylceramide). Toxin binding to dicetyl phosphate or phosphatidylinositol phosphate was inhibited by UTP, ATP, phosphocholine, or p-nitrophenyl phosphate, but not by uracil. We conclude that (a) diphtheria toxin binds specifically to the phosphate portion of certain phospholipids, (b) binding to phospholipids in liposomes is dependent on pH, but is not due only to electrostatic interaction, and (c) binding may be strongly influenced by the composition of adjacent phospholipids that do not bind toxin. We propose that a minor membrane phospholipid (such as phosphatidylinositol phosphate or phosphatidic acid), or that some other phosphorylated membrane molecule (such as a phosphoprotein) may be important in the initial binding of

Life cycle studies of the hexose transporter of Plasmodium species and genetic validation of their essentiality.

Science.gov (United States)

Slavic, Ksenija; Straschil, Ursula; Reininger, Luc; Doerig, Christian; Morin, Christophe; Tewari, Rita; Krishna, Sanjeev

2010-03-01

A Plasmodium falciparum hexose transporter (PfHT) has previously been shown to be a facilitative glucose and fructose transporter. Its expression in Xenopus laevis oocytes and the use of a glucose analogue inhibitor permitted chemical validation of PfHT as a novel drug target. Following recent re-annotations of the P. falciparum genome, other putative sugar transporters have been identified. To investigate further if PfHT is the key supplier of hexose to P. falciparum and to extend studies to different stages of Plasmodium spp., we functionally analysed the hexose transporters of both the human parasite P. falciparum and the rodent parasite Plasmodium berghei using gene targeting strategies. We show here the essential function of pfht for the erythrocytic parasite growth as it was not possible to knockout pfht unless the gene was complemented by an episomal construct. Also, we show that parasites are rescued from the toxic effect of a glucose analogue inhibitor when pfht is overexpressed in these transfectants. We found that the rodent malaria parasite orthologue, P. berghei hexose transporter (PbHT) gene, was similarly refractory to knockout attempts. However, using a single cross-over transfection strategy, we generated transgenic P. berghei parasites expressing a PbHT-GFP fusion protein suggesting that locus is amenable for gene targeting. Analysis of pbht-gfp transgenic parasites showed that PbHT is constitutively expressed through all the stages in the mosquito host in addition to asexual stages. These results provide genetic support for prioritizing PfHT as a target for novel antimalarials that can inhibit glucose uptake and kill parasites, as well as unveiling the expression of this hexose transporter in mosquito stages of the parasite, where it is also likely to be critical for survival.

Day-night changes of energy-rich compounds in crassulacean acid metabolism (CAM) species utilizing hexose and starch.

Science.gov (United States)

Chen, Li-Song; Nose, Akihiro

2004-09-01

Plants with crassulacean acid metabolism (CAM) can be divided into two groups according to the major carbohydrates used for malic acid synthesis, either polysaccharide (starch) or monosaccharide (hexose). This is related to the mechanism and affects energy metabolism in the two groups. In Kalanchoë pinnata and K. daigremontiana, which utilize starch, ATP-dependent phosphofructokinase (tonoplast inorganic pyrophosphatase) activity is greater than inorganic pyrophosphate-dependent phosphofructokinase (tonoplast adenosine triphosphatase) activity, but the reverse is the case in pineapple (Ananas comosus) utilizing hexose. To test the hypothesis that the energy metabolism of the two groups differs, day-night changes in the contents of ATP, ADP, AMP, inorganic phosphate (Pi), phosphoenolpyruvate (PEP) and inorganic pyrophosphate (PPi) in K. pinnata and K. daigremontiana leaves and in pineapple chlorenchyma were analysed. The contents of energy-rich compounds were measured spectrophotometrically in extracts of tissue sampled in the light and dark, using potted plants, kept for 15 d before the experiments in a growth chamber. In the three species, ATP content and adenylate energy charge (AEC) increased in the dark and decreased in the light, in contrast to ADP and AMP. Changes in ATP and AEC were greater in Kalanchoë leaves than in pineapple chlorenchyma. PPi content in the three species increased in the dark, but on illumination it decreased rapidly and substantially, remaining little changed through the rest of the light period. Pi content of Kalanchoë leaves did not change between dark and light, whereas Pi in pineapple chlorenchyma increased in the dark and decreased in the light, and the changes were far greater than in Kalanchoë leaves. Light-dark changes in PEP content in the three species were similar. These results corroborate our hypothesis that day-night changes in the contents of energy-rich compounds differ between CAM species and are related to the

Continuous production of ethanol from hexoses and pentoses using immobilized mixed cultures of Escherichia coli strains

Science.gov (United States)

Unrean, Pornkamol; Srienc, Friedrich

2010-01-01

We have developed highly efficient ethanologenic E. coli strains that selectively consume pentoses and/or hexoses. Mixed cultures of these strains can be used to selectively adjust the sugar utilization kinetics in ethanol fermentations. Based on the kinetics of sugar utilization, we have designed and implemented an immobilized cell system for the optimized continuous conversion of sugars into ethanol. The results confirm that immobilized mixed cultures support a simultaneous conversion of hexoses and pentoses into ethanol at high yield and at a faster rate than immobilized homogenous cells. Continuous ethanol production has been maintained for several weeks at high productivity with near complete sugar utilization. The control of sugar utilization using immobilized mixed cultures can be adapted to any composition of hexoses and pentoses by adjusting the strain distribution of immobilized cells. The approach, therefore, holds promise for ethanol fermentation from lignocellulosic hydrolysates where the feedstock varies in sugar composition. PMID:20699108

Hexose kinases and their role in sugar-sensing and plant development

Directory of Open Access Journals (Sweden)

David eGranot

2013-03-01

Full Text Available Hexose sugars, such as glucose and fructose produced in plants, are ubiquitous in most organisms and are the origin of most of the organic matter found in nature. To be utilized, hexose sugars must first be phosphorylated. The central role of hexose-phosphorylating enzymes has attracted the attention of many researchers, leading to novel discoveries. Only two families of enzymes capable of phosphorylating glucose and fructose have been identified in plants; hexokinases (HXKs and fructokinases (FRKs. Intensive investigations of these two families in numerous plant species have yielded a wealth of knowledge regarding the genes number, enzymatic characterization, intracellular localization and developmental and physiological roles of several HXKs and FRKs. The emerging picture indicates that HXK and FRK enzymes found at specific intracellular locations play distinct roles in plant metabolism and development. Individual HXKs were shown for the first time to be dual-function enzymes - sensing sugar levels independent of their catalytic activity and also controlling gene expression and major developmental pathways, as well as hormonal interactions. FRK, on the other hand, seems to play a central metabolic role in vascular tissues, controlling the amounts of sugars allocated for vascular development. While a clearer picture of the roles of these two types of enzymes is emerging, many questions remain unsolved, such as the specific tissues and types of cells in which these enzymes function, the roles of individual HXK and FRK genes, and how these enzymes interact with hormones in the regulation of developmental processes. It is anticipated that ongoing efforts will broaden our knowledge of these important plant enzymes and their potential uses in the modification of plant traits.

Calcium carbonate phosphate binding ion exchange filtration and accelerated denitrification improve public health standards and combat eutrophication in aquatic ecosystems.

Science.gov (United States)

Yanamadala, Vijay

2005-01-01

Hektoen agar. Initial analyses suggest a strong correlation between phosphate concentrations and bacterial populations; a 66% decrease in phosphate resulted in a 35% reduction in bacterial populations and a 45% reduction in enteropathogenic populations. Likewise, a strong correlation was shown between calcium carbonate concentrations and bacterial reduction greater than that which can be attributed to the phosphate reduction alone. This was followed by the construction of various phosphate binding calcium carbonate filters, which used the ion exchange principle, including a spring loading filter, PVC pipe filter, and a galvanized filter. All were tested with the aid of Stoke's law formulation. The experiment was extremely successful in designing a working phosphate-binding and ammonia-reducing filter, and a large-scale agitator-clarifier filter system is currently being planned for construction in Madrona Marsh; this filter will reduce phosphate and ammonia levels substantially in the following years, bringing ecological, economical, and health-related improvements to the overall ecosystem and habitat.

Oxysterol-binding Protein Activation at Endoplasmic Reticulum-Golgi Contact Sites Reorganizes Phosphatidylinositol 4-Phosphate Pools*

OpenAIRE

Goto, Asako; Charman, Mark; Ridgway, Neale D.

2015-01-01

Oxysterol-binding protein (OSBP) exchanges cholesterol and phosphatidylinositol 4-phosphate (PI-4P) at contact sites between the endoplasmic reticulum (ER) and the trans-Golgi/trans-Golgi network. 25-Hydroxycholesterol (25OH) competitively inhibits this exchange reaction in vitro and causes the constitutive localization of OSBP at the ER/Golgi interface and PI-4P-dependent recruitment of ceramide transfer protein (CERT) for sphingomyelin synthesis. We used PI-4P probes and mass analysis to de...

Interaction between calcium and phosphate adsorption on goethite

NARCIS (Netherlands)

Rietra, R.P.J.J.; Hiemstra, T.; Riemsdijk, van W.H.

2001-01-01

Quantitatively, little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which determine the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO4 in

Interaction of bovine gallbladder mucin and calcium-binding protein: effects on calcium phosphate precipitation.

Science.gov (United States)

Afdhal, N H; Ostrow, J D; Koehler, R; Niu, N; Groen, A K; Veis, A; Nunes, D P; Offner, G D

1995-11-01

Gallstones consist of calcium salts and cholesterol crystals, arrayed on a matrix of gallbladder mucin (GBM), and regulatory proteins like calcium-binding protein (CBP). To determine if interactions between CBP and GBM follow a biomineralization scheme, their mutual binding and effects on CaHPO4 precipitation were studied. Binding of CBP to GBM was assessed by inhibition of the fluorescence of the complex of GBM with bis-1,8-anilinonaphthalene sulfonic acid (bis-ANS). The effects of the proteins on precipitation of CaHPO4 were assessed by nephelometry and gravimetry. Precipitates were analyzed for calcium, phosphate, and protein. CBP and bis-ANS competitively displaced each other from 30 binding sites on mucin, with a 1:1 stoichiometry and similar affinity. The rate of precipitation of CaHPO4 was retarded by mucin and CBP. Precipitate mass was unaffected by GBM alone but decreased with the addition of CBP. Complexing CBP with GBM abolished or moderated this latter effect, altered precipitate morphology, and changed the stoichiometric ratios of Ca to PO4 in the precipitates from 1:1 to 3:2. Mucin and CBP were incorporated into the precipitates. These studies suggest that the formation of calcium-containing gallstones is a biomineralization process regulated by both GBM and CBP.

Characterization of hexose transporters in Yarrowia lipolytica reveals new groups of Sugar Porters involved in yeast growth.

Science.gov (United States)

Lazar, Zbigniew; Neuvéglise, Cécile; Rossignol, Tristan; Devillers, Hugo; Morin, Nicolas; Robak, Małgorzata; Nicaud, Jean-Marc; Crutz-Le Coq, Anne-Marie

2017-03-01

Sugar assimilation has been intensively studied in the model yeast S. cerevisiae, and for two decades, it has been clear that the homologous HXT genes, which encode a set of hexose transporters, play a central role in this process. However, in the yeast Yarrowia lipolytica, which is well-known for its biotechnological applications, sugar assimilation is only poorly understood, even though this yeast exhibits peculiar intra-strain differences in fructose uptake: some strains (e.g., W29) are known to be slow-growing in fructose while others (e.g., H222) grow rapidly under the same conditions. Here, we retrieved 24 proteins of the Sugar Porter family from these two strains, and determined that at least six of these proteins can function as hexose transporters in the heterologous host Saccharomyces cerevisiae EBY.VW4000. Transcriptional studies and deletion analysis in Y. lipolytica indicated that two genes, YHT1 and YHT4, are probably the main players in both strains, with a similar role in the uptake of glucose, fructose, and mannose at various concentrations. The other four genes appear to constitute a set of 'reservoir' hexose transporters with an as-yet unclear physiological role. Furthermore, through examining Sugar Porters of the entire Yarrowia clade, we show that they constitute a dynamic family, within which hexose transport genes have been duplicated and lost several times. Our phylogenetic analyses support the existence of at least three distinct evolutionary groups of transporters which allow yeasts to grow on hexoses. In addition to the well-known and widespread Hxt-type transporters (which are not essential in Y. lipolytica), we highlight a second group of transporters, represented by Yht1, which are phylogenetically related to sensors that play a regulatory role in S. cerevisiae, and a third group, represented by Yht4, previously thought to contain only high-affinity glucose transporters related to Hgt1of Kluyveromyces lactis. Copyright © 2017

Hexose transporter mRNAs for GLUT4, GLUT5, and GLUT12 predominate in human muscle.

Science.gov (United States)

Stuart, Charles A; Yin, Deling; Howell, Mary E A; Dykes, Rhesa J; Laffan, John J; Ferrando, Arny A

2006-11-01

In the past few years, 8 additional members of the facilitative hexose transporter family have been identified, giving a total of 14 members of the SLC2A family of membrane-bound hexose transporters. To determine which of the new hexose transporters were expressed in muscle, mRNA concentrations of 11 glucose transporters (GLUTs) were quantified and compared. RNA from muscle from 10 normal volunteers was subjected to RT-PCR. Primers were designed that amplified 78- to 241-base fragments, and cDNA standards were cloned for GLUT1, GLUT2, GLUT3, GLUT4, GLUT5, GLUT6, GLUT8, GLUT9, GLUT10, GLUT11, GLUT12, and GAPDH. Seven of these eleven hexose transporters were detectable in normal human muscle. The rank order was GLUT4, GLUT5, GLUT12, GLUT8, GLUT11, GLUT3, and GLUT1, with corresponding concentrations of 404 +/- 49, 131 +/- 14, 33 +/- 4, 5.5 +/- 0.5, 4.1 +/- 0.4, 1.2 +/- .0.1, and 0.9 +/- 0.2 copies/ng RNA (means +/- SE), respectively, for the 10 subjects. Concentrations of mRNA for GLUT4, GLUT5, and GLUT12 were much higher than those for the remainder of the GLUTs and together accounted for 98% of the total GLUT isoform mRNA. Immunoblots of muscle homogenates verified that the respective proteins for GLUT4, GLUT5, and GLUT12 were present in normal human muscle. Immunofluorescent studies demonstrated that GLUT4 and GLUT12 were predominantly expressed in type I oxidative fibers; however, GLUT5 was expressed predominantly in type II (white) fibers.

A Hexose Transporter Homologue Controls Glucose Repression in the Methylotrophic Yeast Hansenula polymorpha

NARCIS (Netherlands)

Stasyk, Oleh V.; Stasyk, Olena G.; Komduur, Janet; Veenhuis, Marten; Cregg, James M.; Sibirny, Andrei A.

2004-01-01

Peroxisome biogenesis and synthesis of peroxisomal enzymes in the methylotrophic yeast Hansenula polymorpha are under the strict control of glucose repression. We identified an H. polymorpha glucose catabolite repression gene (HpGCR1) that encodes a hexose transporter homologue. Deficiency in GCR1

Day–Night Changes of Energy-rich Compounds in Crassulacean Acid Metabolism (CAM) Species Utilizing Hexose and Starch

Science.gov (United States)

CHEN, LI-SONG; NOSE, AKIHIRO

2004-01-01

• Background and Aims Plants with crassulacean acid metabolism (CAM) can be divided into two groups according to the major carbohydrates used for malic acid synthesis, either polysaccharide (starch) or monosaccharide (hexose). This is related to the mechanism and affects energy metabolism in the two groups. In Kalanchoë pinnata and K. daigremontiana, which utilize starch, ATP-dependent phosphofructokinase (tonoplast inorganic pyrophosphatase) activity is greater than inorganic pyrophosphate-dependent phosphofructokinase (tonoplast adenosine triphosphatase) activity, but the reverse is the case in pineapple (Ananas comosus) utilizing hexose. To test the hypothesis that the energy metabolism of the two groups differs, day-night changes in the contents of ATP, ADP, AMP, inorganic phosphate (Pi), phosphoenolpyruvate (PEP) and inorganic pyrophosphate (PPi) in K. pinnata and K. daigremontiana leaves and in pineapple chlorenchyma were analysed. • Methods The contents of energy-rich compounds were measured spectrophotometrically in extracts of tissue sampled in the light and dark, using potted plants, kept for 15 d before the experiments in a growth chamber. • Key Results In the three species, ATP content and adenylate energy charge (AEC) increased in the dark and decreased in the light, in contrast to ADP and AMP. Changes in ATP and AEC were greater in Kalanchoë leaves than in pineapple chlorenchyma. PPi content in the three species increased in the dark, but on illumination it decreased rapidly and substantially, remaining little changed through the rest of the light period. Pi content of Kalanchoë leaves did not change between dark and light, whereas Pi in pineapple chlorenchyma increased in the dark and decreased in the light, and the changes were far greater than in Kalanchoë leaves. Light-dark changes in PEP content in the three species were similar. • Conclusions These results corroborate our hypothesis that day–night changes in the contents of energy

Growth rate-regulated expression of the hexose transporter HXT5 in Saccharomyces cerevisiae

NARCIS (Netherlands)

Verwaal, René

2003-01-01

Glucose, which is the most preferred carbon source for the yeast Saccharomyces cerevisiae, is transported across the plasma membrane into cells by hexose transporter (Hxt) proteins. The Hxt proteins are encoded by a multigene family consisting of 20 members. It was shown previously that HXT1-4 and

Nitrite-cured color and phosphate-mediated water binding of pork muscle proteins as affected by calcium in the curing solution.

Science.gov (United States)

Zhao, Jing; Xiong, Youling L

2012-07-01

Calcium is a mineral naturally present in water and may be included into meat products during processing thereby influencing meat quality. Phosphates improve myofibril swelling and meat water-holding capacity (WHC) but can be sensitive to calcium precipitation. In this study, pork shoulder meat was used to investigate the impact of calcium at 0, 250, and 500 ppm and phosphate type [sodium pyrophosphate (PP), tripolyphosphate (TPP), and hexametaphopshate (HMP)] at 10 mM on nitrite-cured protein extract color at various pH levels (5.5, 6.0, and 6.5) and crude myofibril WHC at pH 6.0. Neither calcium nor phosphates present in the curing brines significantly affected the cured color. Increasing the pH tended to promote the formation of metmyoglobin instead of nitrosylmyoglobin. The ability of PP to enhance myofibril WHC was hampered (P meat products. Although not affecting nitrite-cured color, calcium hampers the efficacy of phosphates to promote water binding by muscle proteins, underscoring the importance of water quality for brine-enhanced meat products. © 2012 Institute of Food Technologists®

Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose-5-phosphate binding

DEFF Research Database (Denmark)

Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

1996-01-01

The three conserved aspartic acid residues of the 5-phospho-d-ribosyl a-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... enzymes were dependent on the metal ion present, suggesting a function of the investigated aspartic acid residues both in the binding of ribose 5-phosphate, possibly via a divalent metal ion, and in the interaction with a divalent metal ion during catalysis....

Expression of a putative grapevine hexose transporter in tobacco alters morphogenesis and assimilate partitioning.

Science.gov (United States)

Leterrier, Marina; Atanassova, Rossitza; Laquitaine, Laurent; Gaillard, Cécile; Coutos-Thévenot, Pierre; Delrot, Serge

2003-04-01

Tobacco plants were transformed by leaf disc regeneration with the VvHT1 (Vitis vinifera hexose transporter 1) cDNA under the control of the constitutive CaMV 35S promoter in a sense or antisense orientation. Among the 20 sense plants and 10 antisense plants obtained, two sense plants showed a mutant phenotype when grown in vitro, with stunted growth and an increase in the (leaves+stem)/roots dry weight ratio. The rate of [(3)H]-glucose uptake in leaf discs from these plants was decreased to 25% of the value measured in control plants. The amount of VvHT1 transgene and of host monosaccharide transporter MST transcripts in the leaves were studied by RNA gel blot analysis. The VvHT1 transcripts were usually present, but the amount of MST transcripts was the lowest in the plants that exhibited the most marked phenotype. Although the phenotype was lost when the plants were transferred from in vitro to greenhouse conditions, it was found again in vitro in the progeny obtained by self-pollination or by back-cross. The data show that VvHT1 sense expression resulted in unidirectional post-transcriptional gene inactivation of MST in some of the transformants, with dramatic effects on growth. They provide the first example of plants modified for hexose transport by post-transcriptional gene silencing. Some of the antisense plants also showed reduced expression of MST, and decreased growth. These results indicate that, like the sucrose transporters, hexose transporters play an important role in assimilate transport and in morphogenesis.

Genomes of rumen bacteria encode atypical pathways for fermenting hexoses to short-chain fatty acids

KAUST Repository

Hackmann, Timothy J.; Ngugi, David; Firkins, Jeffrey L.; Tao, Junyi

2017-01-01

Bacteria have been thought to follow only a few well-recognized biochemical pathways when fermenting glucose or other hexoses. These pathways have been chiseled in the stone of textbooks for decades, with most sources rendering them as they appear

Enhanced resistance in Theobroma cacao against oomycete and fungal pathogens by secretion of phosphatidylinositol-3-phosphate-binding proteins.

Science.gov (United States)

Helliwell, Emily E; Vega-Arreguín, Julio; Shi, Zi; Bailey, Bryan; Xiao, Shunyuan; Maximova, Siela N; Tyler, Brett M; Guiltinan, Mark J

2016-03-01

The internalization of some oomycete and fungal pathogen effectors into host plant cells has been reported to be blocked by proteins that bind to the effectors' cell entry receptor, phosphatidylinositol-3-phosphate (PI3P). This finding suggested a novel strategy for disease control by engineering plants to secrete PI3P-binding proteins. In this study, we tested this strategy using the chocolate tree Theobroma cacao. Transient expression and secretion of four different PI3P-binding proteins in detached leaves of T. cacao greatly reduced infection by two oomycete pathogens, Phytophthora tropicalis and Phytophthora palmivora, which cause black pod disease. Lesion size and pathogen growth were reduced by up to 85%. Resistance was not conferred by proteins lacking a secretory leader, by proteins with mutations in their PI3P-binding site, or by a secreted PI4P-binding protein. Stably transformed, transgenic T. cacao plants expressing two different PI3P-binding proteins showed substantially enhanced resistance to both P. tropicalis and P. palmivora, as well as to the fungal pathogen Colletotrichum theobromicola. These results demonstrate that secretion of PI3P-binding proteins is an effective way to increase disease resistance in T. cacao, and potentially in other plants, against a broad spectrum of pathogens. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Increased xylose affinity of Hxt2 through gene shuffling of hexose transporters in Saccharomyces cerevisiae

NARCIS (Netherlands)

Nijland, Jeroen G; Shin, Hyun Yong; de Waal, Paul P; Klaassen, Paul; Driessen, Arnold J M

AIMS: Optimizing D-xylose transport in Saccharomyces cerevisiae is essential for efficient bioethanol production from cellulosic materials. We have used a gene shuffling approach of hexose (Hxt) transporters in order to increase the affinity for D-xylose. METHODS AND RESULTS: Various libraries were

Takifugu rubripes cation independent mannose 6-phosphate receptor: Cloning, expression and functional characterization of the IGF-II binding domain.

Science.gov (United States)

A, Ajith Kumar; Nadimpalli, Siva Kumar

2018-07-01

Mannose 6-phosphate/IGF-II receptor mediated lysosomal clearance of insulin-like growth factor-II is significantly associated with the evolution of placental mammals. The protein is also referred to as the IGF-II receptor. Earlier studies suggested relatively low binding affinity between the receptor and ligand in prototherian and metatherian mammals. In the present study, we cloned the IGF-II binding domain of the early vertebrate fugu fish and expressed it in bacteria. A 72000Da truncated receptor containing the IGF-II binding domain was obtained. Analysis of this protein (covering domains 11-13 of the CIMPR) for its affinity to fish and human IGF-II by ligand blot assays and ELISA showed that the expressed receptor can specifically bind to both fish and human IGF-II. Additionally, a peptide-specific antibody raised against the region of the IGF-II binding domain also was able to recognize the IGF-II binding regions of mammalian and non-mammalian cation independent MPR protein. These interactions were further characterized by Surface Plasma resonance support that the receptor binds to fish IGF-II, with a dissociation constant of 548nM. Preliminary analysis suggests that the binding mechanism as well as the affinity of the fish and human receptor for IGF-II may have varied according to different evolutionary pressures. Copyright © 2018. Published by Elsevier B.V.

Towards Phosphate Detection in Hydroponics Using Molecularly Imprinted Polymer Sensors.

Science.gov (United States)

Storer, Christopher S; Coldrick, Zachary; Tate, Daniel J; Donoghue, Jack Marsden; Grieve, Bruce

2018-02-10

An interdigitated electrode sensor was designed and microfabricated for measuring the changes in the capacitance of three phosphate selective molecularly imprinted polymer (MIP) formulations, in order to provide hydroponics users with a portable nutrient sensing tool. The MIPs investigated were synthesised using different combinations of the functional monomers methacrylic acid (MAA) and N -allylthiourea, against the template molecules diphenyl phosphate, triethyl phosphate, and trimethyl phosphate. A cross-interference study between phosphate, nitrate, and sulfate was carried out for the MIP materials using an inductance, capacitance, and resistance (LCR) meter. Capacitance measurements were taken by applying an alternating current (AC) with a potential difference of 1 V root mean square (RMS) at a frequency of 1 kHz. The cross-interference study demonstrated a strong binding preference to phosphate over the other nutrient salts tested for each formulation. The size of template molecule and length of the functional monomer side groups also determined that a short chain functional monomer in combination with a template containing large R-groups produced the optimal binding site conditions when synthesising a phosphate selective MIP.

Effects of insulin on hexose transport across blood-brain barrier in normoglycemia

International Nuclear Information System (INIS)

Namba, H.; Lucignani, G.; Nehlig, A.; Patlak, C.; Pettigrew, K.; Kennedy, C.; Sokoloff, L.

1987-01-01

The effects of insulin on 3-O-[ 14 C] methylglucose transport across the blood-brain barrier (BBB) were studied in conscious rats under steady-state normoglycemic conditions. The [ 14 C]methylglucose was infused intravenously at a constant rate, and animals were killed at various times between 5 and 30 min after the initiation of the infusion. The time course of the arterial plasma concentration of [ 14 C]methylglucose was determined in timed arterial blood samples taken during the infusion. Local cerebral tissue concentrations of [ 14 C]methylglucose at the time of killing were determined by quantitative autoradiography of brain sections. The rate constants for inward and outward transport of [ 14 C]methylglucose across the BBB, K 1 , and k 2 , respectively, were estimated by a least-squares, best-fit of a kinetic equation to the measured time courses of plasma and tissue concentrations. The equilibrium distribution ration, K 1 /k 2 , for [ 14 C]methylglucose in brain increased by ∼ 10-11% in the hyperinsulinemic animals. Because 3-O-[ 14 C]methylglucose shares the same carrier that transports glucose and other hexoses across the BBB, these results suggest that hyperinsulinemia decreases the rate constants for transport but increases the distribution space for hexoses in brain. These effects are, however, quite small and are probably minor or negligible when compared with the major effects of insulin in other tissues

D-glucose-6-phosphate dehydrogenase (Entner-Doudoroff enzyme) from Pseudomonas fluorescens

International Nuclear Information System (INIS)

Lessmann, D.; Schimz, K.L.; Kurz, G.

1975-01-01

The existence of two different D-glucose-6-phosphate dehydrogenases in Pseudomonas fluorescens has been demonstrated. Based on their different specificity and their different metabolic regulation one enzyme is appointed to the Entner-Doudoroff pathway and the other to the hexose monophosphate pathway. A procedure is described for the isolation of that D-glucose-6-phosphate dehydrogenase which forms part of the Entner-Doudoroff pathway (Entner-Doudoroff enzyme). A 950-fold purification was achieved with an overall yield of 44%. The final preparation, having a specific activity of about 300μmol NADH formed per min per mg protein, was shown to be homogeneous. The molecular weight of the Entner-Doudoroff enzyme has been determined to be 220,000 by gel permeation chromatography, and that of the other enzyme (Zwischenferment) has been shown to be 265,000. The pI of the Entner-Doudoroff enzyme has been shown to be 5.24 and that of the Zwischenferment 4.27. The Entner-Doudoroff enzyme is stable in the range of pH 6 to 10.5 and shows its maximal acivity at pH 8.9. The Entner-Doudoroff enzyme showed specificity for NAD + as well as for NADP + and exhibited homotropic effects for D-glucose 6-phosphate. It is inhibited by ATP which acts as a negative allosteric effector. Other nucleoside triphosphates as well as ADP are also inhibitory. The enzyme catalyzes the transfer of the axial hydrogen at carbon-1 of β-D-glucopyranose 6-phosphate to the si face of carbon-4 of the nicotinamide ring and must be classified as B-side stereospecific dehydrogenase. (orig.) [de

Identification of Selective Inhibitors of the Plasmodium falciparum Hexose Transporter PfHT by Screening Focused Libraries of Anti-Malarial Compounds.

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Diana Ortiz

Full Text Available Development of resistance against current antimalarial drugs necessitates the search for novel drugs that interact with different targets and have distinct mechanisms of action. Malaria parasites depend upon high levels of glucose uptake followed by inefficient metabolic utilization via the glycolytic pathway, and the Plasmodium falciparum hexose transporter PfHT, which mediates uptake of glucose, has thus been recognized as a promising drug target. This transporter is highly divergent from mammalian hexose transporters, and it appears to be a permease that is essential for parasite viability in intra-erythrocytic, mosquito, and liver stages of the parasite life cycle. An assay was developed that is appropriate for high throughput screening against PfHT based upon heterologous expression of PfHT in Leishmania mexicana parasites that are null mutants for their endogenous hexose transporters. Screening of two focused libraries of antimalarial compounds identified two such compounds that are high potency selective inhibitors of PfHT compared to human GLUT1. Additionally, 7 other compounds were identified that are lower potency and lower specificity PfHT inhibitors but might nonetheless serve as starting points for identification of analogs with more selective properties. These results further support the potential of PfHT as a novel drug target.

Ophthalmic acid accumulation in an Escherichia coli mutant lacking the conserved pyridoxal 5′-phosphate-binding protein YggS

OpenAIRE

Ito, Tomokazu; Yamauchi, Ayako; Hemmi, Hisashi; Yoshimura, Tohru

2016-01-01

Escherichia coli YggS is a highly conserved pyridoxal 5′-phosphate (PLP)-binding protein whose biochemical function is currently unknown. A previous study with a yggS-deficient E. coli strain (ΔyggS) demonstrated that YggS controls l-Ile- and l-Val-metabolism by modulating 2-ketobutyrate (2-KB), l-2-aminobutyrate (l-2-AB), and/or coenzyme A (CoA) availability in a PLP-dependent fashion. In this study, we found that ΔyggS accumulates an unknown metabolite as judged by amino acid analyses. LC/M...

Insights into phosphate cooperativity and influence of substrate modifications on binding and catalysis of hexameric purine nucleoside phosphorylases.

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Priscila O de Giuseppe

Full Text Available The hexameric purine nucleoside phosphorylase from Bacillus subtilis (BsPNP233 displays great potential to produce nucleoside analogues in industry and can be exploited in the development of new anti-tumor gene therapies. In order to provide structural basis for enzyme and substrates rational optimization, aiming at those applications, the present work shows a thorough and detailed structural description of the binding mode of substrates and nucleoside analogues to the active site of the hexameric BsPNP233. Here we report the crystal structure of BsPNP233 in the apo form and in complex with 11 ligands, including clinically relevant compounds. The crystal structure of six ligands (adenine, 2'deoxyguanosine, aciclovir, ganciclovir, 8-bromoguanosine, 6-chloroguanosine in complex with a hexameric PNP are presented for the first time. Our data showed that free bases adopt alternative conformations in the BsPNP233 active site and indicated that binding of the co-substrate (2'deoxyribose 1-phosphate might contribute for stabilizing the bases in a favorable orientation for catalysis. The BsPNP233-adenosine complex revealed that a hydrogen bond between the 5' hydroxyl group of adenosine and Arg(43* side chain contributes for the ribosyl radical to adopt an unusual C3'-endo conformation. The structures with 6-chloroguanosine and 8-bromoguanosine pointed out that the Cl(6 and Br(8 substrate modifications seem to be detrimental for catalysis and can be explored in the design of inhibitors for hexameric PNPs from pathogens. Our data also corroborated the competitive inhibition mechanism of hexameric PNPs by tubercidin and suggested that the acyclic nucleoside ganciclovir is a better inhibitor for hexameric PNPs than aciclovir. Furthermore, comparative structural analyses indicated that the replacement of Ser(90 by a threonine in the B. cereus hexameric adenosine phosphorylase (Thr(91 is responsible for the lack of negative cooperativity of phosphate binding

Structural Isosteres of Phosphate Groups in the Protein Data Bank.

Science.gov (United States)

Zhang, Yuezhou; Borrel, Alexandre; Ghemtio, Leo; Regad, Leslie; Boije Af Gennäs, Gustav; Camproux, Anne-Claude; Yli-Kauhaluoma, Jari; Xhaard, Henri

2017-03-27

We developed a computational workflow to mine the Protein Data Bank for isosteric replacements that exist in different binding site environments but have not necessarily been identified and exploited in compound design. Taking phosphate groups as examples, the workflow was used to construct 157 data sets, each composed of a reference protein complexed with AMP, ADP, ATP, or pyrophosphate as well other ligands. Phosphate binding sites appear to have a high hydration content and large size, resulting in U-shaped bioactive conformations recurrently found across unrelated protein families. A total of 16 413 replacements were extracted, filtered for a significant structural overlap on phosphate groups, and sorted according to their SMILES codes. In addition to the classical isosteres of phosphate, such as carboxylate, sulfone, or sulfonamide, unexpected replacements that do not conserve charge or polarity, such as aryl, aliphatic, or positively charged groups, were found.

Binding of C-reactive protein to human polymorphonuclear leukocytes: evidence for association of binding sites with Fc receptors

International Nuclear Information System (INIS)

Mueller, H.; Fehr, J.

1986-01-01

The functional similarities between C-reactive protein (CRP) and IgG raised the question as to whether human phagocytes are stimulated by CRP in the same way as by binding of antigen-complexes or aggregated IgG to their Fc receptors. Studies with the use of highly purified 125 I-labeled CRP showed specific and saturable binding to human polymorphonuclear leukocytes (PNM) with a K/sub D/ of 10.5 +/- 5.7 x 10 -8 M only when carried out in heat-inactivated plasma. The number of specific binding sites per cell was estimated at 1 to 3 x 10 6 . Competitive inhibition of CRP binding by antigen-complexed or aggregated IgG suggests CRP binding sites to be associated IgG suggests CRP binding sites to be associated with PMN Fc receptors. Only when assayed in heat-inactivated plasma did CRP binding induce adherence of cells to tissue culture dishes. However, no metabolic and potentially cytotoxic simulation of PMN was detected during CRP plasma-dependent attachment to surfaces: induction of aggregation, release of secondary granule constituents, and activation of the hexose monophosphate pathway were not observed. These results imply that CRP-PMN interactions is dependent on an additional factor present in heat-inactivated plasma and is followed only by a complement-independent increase in PMN attachment to surfaces. Because CRP was found to be deposits at sites of tissue injury, the CRP-mediated adherence of PMN may be an important step in localizing an inflammatory focus

31P NMR study of the interaction of inorganic phosphate with bovine copper-zinc superoxide dismutase

International Nuclear Information System (INIS)

de Freitas, D.M.; Luchinat, C.; Banci, L.; Bertini, I.; Valentine, J.S.

1987-01-01

Paramagnetic effect of 31 P phosphate resonances caused by Cu(II) ions in native and phenylglyoxal-modified bovine Cu,Zn-superoxide dismutase have been used to monitor the interaction of phosphate with these proteins. T 2 values are found to be 70 times smaller than T 1 , indicating that some mechanisms, as yet undefined, contribute to the line width. Using T 1 measurements, it was determined that the affinity constants for phosphate binding to the native protein are 20 +/- 4 and 34 +/- 3 M -1 at pH 8.0 and 7.0 respectively, and that the Cu(II)-phosphate distance 5.3 A. At pH 6.3, two binding sites are observed, one at a distance >7 A with an affinity constant >100 M -1 and another at approximately 5 A with an affinity constant of 10 M -1 . Modification of the protein with phenylglyoxal causes the affinity of phosphate for the same sites to decrease by a factor of 3 at pH 6.3. These results indicate that phosphate does not bind directly to Cu(II) but to a site close by. It was concluded that the site of phosphate binding is Arg-141, which in known from X-ray structural evidence to be located approximately 5 Angstrom form the copper center. 26 references, 4 figures

Characterization of the sterol and phosphatidylinositol 4-phosphate binding properties of Golgi-associated OSBP-related protein 9 (ORP9.

Directory of Open Access Journals (Sweden)

Xinwei Liu

Full Text Available Oxysterol binding protein (OSBP and OSBP-related proteins (ORPS have a conserved lipid-binding fold that accommodates cholesterol, oxysterols and/or phospholipids. The diversity of OSBP/ORPs and their potential ligands has complicated the analysis of transfer and signalling properties of this mammalian gene family. In this study we explored the use of the fluorescent sterol cholestatrienol (CTL to measure sterol binding by ORP9 and competition by other putative ligands. Relative to cholesterol, CTL and dehydroergosterol (DHE were poor ligands for OSBP. In contrast, both long (ORP9L and short (ORP9S variants of ORP9 rapidly extracted CTL, and to a lesser extent DHE, from liposomes. ORP9L and ORP9S also extracted [32P]phosphatidylinositol 4-phosphate (PI-4P from liposomes, which was inhibited by mutating two conserved histidine residues (HH488,489AA at the entrance to the binding pocket but not by a mutation in the lid region that inhibited cholesterol binding. Results of direct binding and competition assays showed that phosphatidylserine was poorly extracted from liposomes by ORP9 compared to CTL and PI-4P. ORP9L and PI-4P did not co-localize in the trans-Golgi/TGN of HeLa cells, and siRNA silencing of ORP9L expression did not affect PI-4P distribution in the Golgi apparatus. However, transient overexpression of ORP9L or ORP9S in CHO cells, but not the corresponding PI-4P binding mutants, prevented immunostaining of Golgi-associated PI-4P. The apparent sequestration of Golgi PI-4P by ORP9S was identified as a possible mechanism for its growth inhibitory effects. These studies identify ORP9 as a dual sterol/PI-4P binding protein that could regulate PI-4P in the Golgi apparatus.

Characterization of the sterol and phosphatidylinositol 4-phosphate binding properties of Golgi-associated OSBP-related protein 9 (ORP9).

Science.gov (United States)

Liu, Xinwei; Ridgway, Neale D

2014-01-01

Oxysterol binding protein (OSBP) and OSBP-related proteins (ORPS) have a conserved lipid-binding fold that accommodates cholesterol, oxysterols and/or phospholipids. The diversity of OSBP/ORPs and their potential ligands has complicated the analysis of transfer and signalling properties of this mammalian gene family. In this study we explored the use of the fluorescent sterol cholestatrienol (CTL) to measure sterol binding by ORP9 and competition by other putative ligands. Relative to cholesterol, CTL and dehydroergosterol (DHE) were poor ligands for OSBP. In contrast, both long (ORP9L) and short (ORP9S) variants of ORP9 rapidly extracted CTL, and to a lesser extent DHE, from liposomes. ORP9L and ORP9S also extracted [32P]phosphatidylinositol 4-phosphate (PI-4P) from liposomes, which was inhibited by mutating two conserved histidine residues (HH488,489AA) at the entrance to the binding pocket but not by a mutation in the lid region that inhibited cholesterol binding. Results of direct binding and competition assays showed that phosphatidylserine was poorly extracted from liposomes by ORP9 compared to CTL and PI-4P. ORP9L and PI-4P did not co-localize in the trans-Golgi/TGN of HeLa cells, and siRNA silencing of ORP9L expression did not affect PI-4P distribution in the Golgi apparatus. However, transient overexpression of ORP9L or ORP9S in CHO cells, but not the corresponding PI-4P binding mutants, prevented immunostaining of Golgi-associated PI-4P. The apparent sequestration of Golgi PI-4P by ORP9S was identified as a possible mechanism for its growth inhibitory effects. These studies identify ORP9 as a dual sterol/PI-4P binding protein that could regulate PI-4P in the Golgi apparatus.

Steric Effects on the Binding of Phosphate and Polyphosphate Anions by Zinc(II) and Copper(II) Dinuclear Complexes of m-Xylyl-bis-cyclen.

Science.gov (United States)

Esteves, Catarina V; Esteban-Gómez, David; Platas-Iglesias, Carlos; Tripier, Raphaël; Delgado, Rita

2018-05-11

The triethylbenzene-bis-cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) compound (tbmce) was designed with an imposed structural rigidity at the m-xylyl spacer to be compared to a less restrained and known parent compound (bmce). The framework of both compounds differs only in the substituents of the m-xylyl spacer. The study was centered in the differences observed in the acid-base reactions of both compounds, their copper(II) and zinc(II) complexation behaviors, as well as in the uptake of phosphate and polyphosphate anions (HPPi 3- , ATP 4- , ADP 3- , AMP 2- , PhPO 4 2- , and HPO 4 2- ). On the one hand, the acid-base reactions showed lower values for the third and fourth protonation constants of tbmce than for bmce, suggesting that the ethyl groups of the spacer in tbmce force the two cyclen units to more conformational restricted positions. On the other hand, the stability constant values for copper(II) and zinc(II) complexes revealed that bmce is a better chelator than tbmce pointing out to additional conformational restraints imposed by the triethylbenzene spacer. The binding studies of phosphates by the dinuclear copper(II) and zinc(II) complexes showed much smaller effective association constants for the dicopper complexes. Single-crystal X-ray and computational (density functional theory) studies suggest that anion binding promotes the formation of tetranuclear entities in which anions are bridging the metal centers. Our studies also revealed the dinuclear zinc(II) complex of bmce as a promising receptor for phosphate anions, with the largest effective association constant of 5.94 log units being observed for the formation of [Zn 2 bmce(HPPi)] + . Accordingly, a colorimetric study via an indicator displacement assay to detect phosphates in aqueous solution found that the [Zn 2 bmce] 4+ complex acts as the best receptor for pyrophosphate displaying a detection limit of 2.5 nM by changes visible to naked eye.

Regulation of photosynthesis by end-product accumulation in leaves of plants storing starch, sucrose, and hexose sugars.

Science.gov (United States)

Goldschmidt, E E; Huber, S C

1992-08-01

In the present study, leaves of different plant species were girdled by the hot wax collar method to prevent export of assimilates. Photosynthetic activity of girdled and control leaves was evaluated 3 to 7 days later by two methods: (a) carbon exchange rate (CER) of attached leaves was determined under ambient CO(2) concentrations using a closed gas system, and (b) maximum photosynthetic capacity (A(max)) was determined under 3% CO(2) with a leaf disc O(2) electrode. Starch, hexoses, and sucrose were determined enzymically. Typical starch storers like soybean (Glycine max L.) (up to 87.5 milligrams of starch per square decimeter in girdled leaves), cotton (Gossypium hirsutum L.), and cucumber (Cucumis sativus L.) responded to 7 days of girdling by increased (80-100%) stomatal resistance (r(s)) and decreased A(max) (>50%). On the other hand, spinach (Spinacia oleracea L.), a typical sucrose storer (up to 160 milligrams of sucrose per square decimeter in girdled leaves), showed only a slight reduction in CER and almost no change in A(max). Intermediate plants like tomato (Lycopersicon esculentum Mill.), sunflower (Helianthus annuus L.), broad bean (Vicia faba L.), bean (Phaseolus vulgaris L.), and pea (Pisum sativum L.), which upon girdling store both starch and sucrose, responded to the girdle by a considerable reduction in CER but only moderate inhibition of A(max), indicating that the observed reduction in CER was primarily a stomatal response. Both the wild-type tobacco (Nicotiana sylvestris) (which upon girdling stored starch and hexoses) and the starchless mutant (which stored only hexoses, up to 90 milligrams per square decimeter) showed 90 to 100% inhibition of CER and approximately 50% inhibition of A(max). In general, excised leaves (6 days) behaved like girdled leaves of the respective species, showing 50% reduction of A(max) in wild-type and starchless N. sylvestris but only slight decline of A(max) in spinach. The results of the present study

Binding of Divalent Magnesium by Escherichia coli Phosphoribosyl Diphosphate Synthetase

DEFF Research Database (Denmark)

Willemoës, Martin; Hove-Jensen, Bjarne

1997-01-01

The mechanism of binding of the substrates MgATP and ribose 5-phosphate as well as Mg2+ to the enzyme 5-phospho-d-ribosyl a-1-diphosphate synthetase from Escherichia coli has been analyzed. By use of the competive inhibitors of ATP and ribose 5-phosphate binding, a,ß-methylene ATP and (+)-1-a,2-a...

Oxysterol-binding Protein Activation at Endoplasmic Reticulum-Golgi Contact Sites Reorganizes Phosphatidylinositol 4-Phosphate Pools*

Science.gov (United States)

Goto, Asako; Charman, Mark; Ridgway, Neale D.

2016-01-01

Oxysterol-binding protein (OSBP) exchanges cholesterol and phosphatidylinositol 4-phosphate (PI-4P) at contact sites between the endoplasmic reticulum (ER) and the trans-Golgi/trans-Golgi network. 25-Hydroxycholesterol (25OH) competitively inhibits this exchange reaction in vitro and causes the constitutive localization of OSBP at the ER/Golgi interface and PI-4P-dependent recruitment of ceramide transfer protein (CERT) for sphingomyelin synthesis. We used PI-4P probes and mass analysis to determine how OSBP controls the availability of PI-4P for this metabolic pathway. Treatment of fibroblasts or Chinese hamster ovary (CHO) cells with 25OH caused a 50–70% reduction in Golgi-associated immunoreactive PI-4P that correlated with Golgi localization of OSBP. In contrast, 25OH caused an OSBP-dependent enrichment in Golgi PI-4P that was detected with a pleckstrin homology domain probe. The cellular mass of phosphatidylinositol monophosphates and Golgi PI-4P measured with an unbiased PI-4P probe (P4M) was unaffected by 25OH and OSBP silencing, indicating that OSBP shifts the distribution of PI-4P upon localization to ER-Golgi contact sites. The PI-4P and sterol binding activities of OSBP were both required for 25OH activation of sphingomyelin synthesis, suggesting that 25OH must be exchanged for PI-4P to be concentrated at contact sites. We propose a model wherein 25OH activation of OSBP promotes the binding and retention of PI-4P at ER-Golgi contact sites. This pool of PI-4P specifically recruits pleckstrin homology domain-containing proteins involved in lipid transfer and metabolism, such as CERT. PMID:26601944

Interaction between calcium and phosphate adsorption on goethite.

Science.gov (United States)

Rietra, R P; Hiemstra, T; van Riemsdijk, W H

2001-08-15

Quantitatively, little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which determine the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO4 in soils and sediments, but the binding behavior of PO4 in these systems often differs significantly from adsorption studies on metal hydroxides in laboratory. The interaction between PO4 and Ca adsorption was studied on goethite because Ca can influence the PO4 adsorption equilibria. Since adsorption interactions are very difficult to discriminate from precipitation reactions, conditions were chosen to prevent precipitation of Ca-PO4 solids. Adsorption experiments of PO4 and Ca, individually and in combination, show a strong interaction between adsorbed Ca and PO4 on goethite for conditions below the saturation index of apatite. It is shown that it is possible to predict the adsorption and interaction of PO4 and Ca on electrostatic arguments using the model parameter values derived from the single-ion systems and without invoking ternary complex formation or precipitation. The model enables the prediction of the Ca-PO4 interaction for environmentally relevant calcium and phosphate concentrations.

Factor VII and protein C are phosphatidic acid-binding proteins.

Science.gov (United States)

Tavoosi, Narjes; Smith, Stephanie A; Davis-Harrison, Rebecca L; Morrissey, James H

2013-08-20

Seven proteins in the human blood clotting cascade bind, via their GLA (γ-carboxyglutamate-rich) domains, to membranes containing exposed phosphatidylserine (PS), although with membrane binding affinities that vary by 3 orders of magnitude. Here we employed nanodiscs of defined phospholipid composition to quantify the phospholipid binding specificities of these seven clotting proteins. All bound preferentially to nanobilayers in which PS headgroups contained l-serine versus d-serine. Surprisingly, however, nanobilayers containing phosphatidic acid (PA) bound substantially more of two of these proteins, factor VIIa and activated protein C, than did equivalent bilayers containing PS. Consistent with this finding, liposomes containing PA supported higher proteolytic activity by factor VIIa and activated protein C toward their natural substrates (factors X and Va, respectively) than did PS-containing liposomes. Moreover, treating activated human platelets with phospholipase D enhanced the rates of factor X activation by factor VIIa in the presence of soluble tissue factor. We hypothesize that factor VII and protein C bind preferentially to the monoester phosphate of PA because of its accessibility and higher negative charge compared with the diester phosphates of most other phospholipids. We further found that phosphatidylinositol 4-phosphate, which contains a monoester phosphate attached to its myo-inositol headgroup, also supported enhanced enzymatic activity of factor VIIa and activated protein C. We conclude that factor VII and protein C bind preferentially to monoester phosphates, which may have implications for the function of these proteases in vivo.

Ancestral mutations as a tool for solubilizing proteins: The case of a hydrophobic phosphate-binding protein

Directory of Open Access Journals (Sweden)

Daniel Gonzalez

2014-01-01

Full Text Available Stable and soluble proteins are ideal candidates for functional and structural studies. Unfortunately, some proteins or enzymes can be difficult to isolate, being sometimes poorly expressed in heterologous systems, insoluble and/or unstable. Numerous methods have been developed to address these issues, from the screening of various expression systems to the modification of the target protein itself. Here we use a hydrophobic, aggregation-prone, phosphate-binding protein (HPBP as a case study. We describe a simple and fast method that selectively uses ancestral mutations to generate a soluble, stable and functional variant of the target protein, here named sHPBP. This variant is highly expressed in Escherichia coli, is easily purified and its structure was solved at much higher resolution than its wild-type progenitor (1.3 versus 1.9 Å, respectively.

Calcium-phosphate-osteopontin particles for caries control

DEFF Research Database (Denmark)

Schlafer, Sebastian; Birkedal, Henrik; Olsen, Jakob

2016-01-01

Caries is caused by acid production in biofilms on dental surfaces. Preventing caries therefore involves control of microorganisms and/or the acid produced. Here, calcium-phosphate-osteopontin particles are presented as a new approach to caries control. The particles are made by co......-precipitation and designed to bind to bacteria in biofilms, impede biofilm build-up without killing the microflora, and release phosphate ions to buffer bacterial acid production if the pH decreases below 6. Analysis of biofilm formation and pH in a five-species biofilm model for dental caries showed that treatment......H always remained above 5.5. Hence, calcium-phosphate-osteopontin particles show potential for applications in caries control....

Oxysterol-binding Protein Activation at Endoplasmic Reticulum-Golgi Contact Sites Reorganizes Phosphatidylinositol 4-Phosphate Pools.

Science.gov (United States)

Goto, Asako; Charman, Mark; Ridgway, Neale D

2016-01-15

Oxysterol-binding protein (OSBP) exchanges cholesterol and phosphatidylinositol 4-phosphate (PI-4P) at contact sites between the endoplasmic reticulum (ER) and the trans-Golgi/trans-Golgi network. 25-Hydroxycholesterol (25OH) competitively inhibits this exchange reaction in vitro and causes the constitutive localization of OSBP at the ER/Golgi interface and PI-4P-dependent recruitment of ceramide transfer protein (CERT) for sphingomyelin synthesis. We used PI-4P probes and mass analysis to determine how OSBP controls the availability of PI-4P for this metabolic pathway. Treatment of fibroblasts or Chinese hamster ovary (CHO) cells with 25OH caused a 50-70% reduction in Golgi-associated immunoreactive PI-4P that correlated with Golgi localization of OSBP. In contrast, 25OH caused an OSBP-dependent enrichment in Golgi PI-4P that was detected with a pleckstrin homology domain probe. The cellular mass of phosphatidylinositol monophosphates and Golgi PI-4P measured with an unbiased PI-4P probe (P4M) was unaffected by 25OH and OSBP silencing, indicating that OSBP shifts the distribution of PI-4P upon localization to ER-Golgi contact sites. The PI-4P and sterol binding activities of OSBP were both required for 25OH activation of sphingomyelin synthesis, suggesting that 25OH must be exchanged for PI-4P to be concentrated at contact sites. We propose a model wherein 25OH activation of OSBP promotes the binding and retention of PI-4P at ER-Golgi contact sites. This pool of PI-4P specifically recruits pleckstrin homology domain-containing proteins involved in lipid transfer and metabolism, such as CERT. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Expression profiles of glyceraldehyde-3-phosphate dehydrogenase from Clonorchis sinensis: a glycolytic enzyme with plasminogen binding capacity.

Science.gov (United States)

Hu, Yue; Zhang, Erhong; Huang, Lisi; Li, Wenfang; Liang, Pei; Wang, Xiaoyun; Xu, Jin; Huang, Yan; Yu, Xinbing

2014-12-01

Globally, 15-20 million people are infected with Clonorchis sinensis (C. sinensis) which results in clonorchiasis. In China, clonorchiasis is considered to be one of the fastest-growing food-borne parasitic diseases. That more key molecules of C. sinensis are characterized will be helpful to understand biology and pathogenesis of the carcinogenic liver fluke. Glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) from many species have functions other than their catalytic role in glycolysis. In the present study, we analyzed the sequence and structure of GAPDH from C. sinensis (CsGAPDH) by using bioinformatics tools and obtained its recombinant protein by prokaryotic expression system, to learn its expression profiles and molecular property. CsGAPDH could bind to human intrahepatic biliary epithelial cell in vivo and in vitro by the method of immunofluorescence assays. CsGAPDH also disturbed in lumen of biliary tract near to the parasite in the liver of infected rat. Western blotting analysis together with immunofluorescence assay indicated that CsGAPDH was a component of excretory/secretory proteins (CsESPs) and a surface-localized protein of C. sinensis. Quantitative real-time PCR (Q-PCR) and Western blotting demonstrated that CsGAPDHs are expressed at the life stages of adult worm, metacercaria, and egg, but the expression levels were different from each other. Recombinant CsGAPDH (rCsGAPDH) was confirmed to have the capacity to catalyze the conversion of glyceraldehyde 3-phosphate to D-glycerate 1,3-bisphosphate which was inhibited by AMP in a dose-dependent manner. In addition, rCsGAPDH was able to interact with human plasminogen in a dose-dependent manner by ELISA. The interaction could be inhibited by lysine. The plasminogen binding capacity of rCsGAPDH along with the distribution of CsGAPDH in vivo and in the liver of C. sinensis-infected rat hinted that surface-localized CsGAPDH might play an important role in host invasion of the worm besides its glycolytic

Interaction between the PH and START domains of ceramide transfer protein competes with phosphatidylinositol 4-phosphate binding by the PH domain.

Science.gov (United States)

Prashek, Jennifer; Bouyain, Samuel; Fu, Mingui; Li, Yong; Berkes, Dusan; Yao, Xiaolan

2017-08-25

De novo synthesis of the sphingolipid sphingomyelin requires non-vesicular transport of ceramide from the endoplasmic reticulum to the Golgi by the multidomain protein ceramide transfer protein (CERT). CERT's N-terminal pleckstrin homology (PH) domain targets it to the Golgi by binding to phosphatidylinositol 4-phosphate (PtdIns(4)P) in the Golgi membrane, whereas its C-terminal StAR-related lipid transfer domain (START) carries out ceramide transfer. Hyperphosphorylation of a serine-rich motif immediately after the PH domain decreases both PtdIns(4)P binding and ceramide transfer by CERT. This down-regulation requires both the PH and START domains, suggesting a possible inhibitory interaction between the two domains. In this study we show that isolated PH and START domains interact with each other. The crystal structure of a PH-START complex revealed that the START domain binds to the PH domain at the same site for PtdIns(4)P-binding, suggesting that the START domain competes with PtdIns(4)P for association with the PH domain. We further report that mutations disrupting the PH-START interaction increase both PtdIns(4)P-binding affinity and ceramide transfer activity of a CERT-serine-rich phosphorylation mimic. We also found that these mutations increase the Golgi localization of CERT inside the cell, consistent with enhanced PtdIns(4)P binding of the mutant. Collectively, our structural, biochemical, and cellular investigations provide important structural insight into the regulation of CERT function and localization. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Cell kinetics of differentiation of Na+-dependent hexose transport in a cultured renal epithelial cell line

International Nuclear Information System (INIS)

Cook, J.S.; Weiss, E.R.

1985-01-01

Fully differentiated cells of the renal proximal tubule have the capability of taking up hexoses across their apical borders by transport coupled to the Na + -electrochemical gradient. This property is also found in postconfluent cultures of the cloned cell line LLC-PK 1 , a morphologically polarized line of renal cells. Postconfluent cells develop the Na + -dependent capacity to transport hexoses at their apical surface. This function is not observable during the growth phase of the cultures. To analyze the developmental process at the cellular level a method has been derived to separate transporting cells, expressing the differentiated function, from nontransporting cells. The method is based on the swelling of the cells accompanying the uptake of the nonmetabolizable glucose analog alpha methylglucoside. The swollen cells have a lower buoyant density than the undifferentiated cells and may be separated from them on density gradients. Analysis of the distribution of cells on such gradients shows that after the cells reach confluence the undifferentiated subpopulation is recruited onto the differentiation pathway with a rate constant of 0.2 per day, that 5 to 7 days are required for a cell to traverse this pathway to the fully differentiated state, and that once the maximum uptake capacity is achieved the cells do not develop further

Development of nanosensors for studying intracellular phosphate levels

DEFF Research Database (Denmark)

Gu, Hong

-time monitoring of Pi metabolism in living cells, providing a new tool for fluxomics (measurement of metabolic flux), analysis of pathophysiology or changes of Pi during cell activity. Transformation of plants with FLIPs had resulted in only low expression levels. As an alternative a protein transduction domain......Abstract Inorganic phosphate (Pi) is an essential macronutrient that plays a central role in metabolism and signal transduction in plants. Uptake, compartmentation and transport are important players of cellular Pi homeostasis; however, methods to determine the cellular phosphate concentration...... of a substrate-binding protein linked to two fluorescent reporter proteins. Substrate binding changes the conformation of the nanosensor and, hence, the efficiency of fluorescence resonance energy transfer (FRET) between the reporter proteins. The aim of the present project was to develop nanosensors for Pi...

A novel analytical method for in vivo phosphate tracking (Corrigendum in FEBS Letters, 2007, 581 p. 579)

DEFF Research Database (Denmark)

Gu, H.; Lalonde, S.; Okumoto, S.

2006-01-01

Genetically-encoded fluorescence resonance energy transfer (FRET) sensors for phosphate (Pi) (FLIPPi) were engineered by fusing a predicted Synechococcus phosphate-binding protein (PiBP) to eCFP and Venus. Purified fluorescent indicator protein for inorganic phosphate (FLIPPi), in which the fluor...

Conglutinin binds the HIV-1 envelope glycoprotein gp 160 and inhibits its interaction with cell membrane CD4

DEFF Research Database (Denmark)

Andersen, Ove; Sørensen, A M; Svehag, S E

1991-01-01

The highly glycosylated envelope glycoprotein (gp 160) of human immunodeficiency virus (HIV) interacts with the CD4 molecule present on the membrane of CD4+ cells and is involved in the pathobiology of HIV infection. Lectins bind glycoproteins through non-covalent interactions with specific hexose...... residues. The mammalian C-type lectin bovine conglutinin was examined for its ability to interact with recombinant gp160 (rgp160) produced in vaccinia virus-infected BHK21 cells. Specific binding of conglutinin to rgp160 was demonstrated by ELISA. The interaction of bovine conglutinin with rgp160...... of the binding of rgp160 to the CD4 receptor on CEM 13 cells, as demonstrated by FACS analyses. These results indicate that conglutinin may inhibit the infection with HIV-1 through its interaction with the viral envelope glycoprotein....

Yeast phospholipase C is required for stability of casein kinase I Yck2p and expression of hexose transporters

Czech Academy of Sciences Publication Activity Database

Zhang, T.; Galdieri, L.; Hašek, Jiří; Vančura, A.

2017-01-01

Roč. 364, č. 22 (2017), č. článku fnx227. ISSN 0378-1097 R&D Projects: GA ČR(CZ) GA16-05497S Institutional support: RVO:61388971 Keywords : phospholipase C * casein kinase I * hexose transporters Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 1.765, year: 2016

Thioredoxin binding site of phosphoribulokinase overlaps the catalytic site

International Nuclear Information System (INIS)

Porter, M.A.; Hartman, F.C.

1986-01-01

The ATP-regulatory binding site of phosphoribulokinase was studied using bromoacetylethanolamine phosphate (BrAcNHEtOP). BrAcNHEtOP binds to the active-regulatory binding site of the protein. Following trypsin degradation of the labeled protein, fragments were separated by HPLC and sequenced. (DT)

Fermentation of hexoses to ethanol

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, Lena [Goeteborg Univ. (Sweden). Dept. of General and Marine Microbiology]|[Chalmers Univ. of Technology, Goeteborg (Sweden). Dept of Chemical Reaction Engineering

2000-06-01

The Goals of the project has been: to increase the ethanol yield by reducing the by-product formation, primarily biomass and glycerol, and to prevent stuck fermentations, i.e. to maintain a high ethanol production rate simultaneously with a high ethanol yield. The studies have been performed both in defined laboratory media and in a mixture of wood- and wheat hydrolysates. The yeast strains used have been both industrial strains of bakers yeast, Saccharomyces cerevisiae, and haploid laboratory strains. The Relevance of these studies with respect to production of ethanol to be used as fuel is explained by: With the traditional process design used today, it is very difficult to reach a yield of more than 90 % of the theoretical maximal value of ethanol based on fermented hexose. During 'normal' growth and fermentation conditions in either anaerobic batch or chemostat cultures, substrate is lost as biomass and glycerol in the range of 8 to 11 % and 6 to 11 % of the substrate consumed (kg/kg). It is essential to reduce these by-products. Traditional processes are mostly batch processes, in which there is a risk that the biocatalyst, i.e. the yeast, may become inactivated. If for example yeast biomass production is avoided by use of non-growing systems, the ethanol production rate is instantaneously reduced by at least 50%. Unfortunately, even if yeast biomass production is not avoided on purpose, it is well known that stuck fermentations caused by cell death is a problem in large scale yeast processes. The main reason for stuck fermentations is nutrient imbalances. For a good process economy, it is necessary to ensure process accessibility, i.e. to maintain a high and reproducible production rate. This will both considerably reduce the necessary total volume of the fermentors (and thereby the investment costs), and moreover minimize undesirable product fall-out.

Phosphate control in dialysis

Directory of Open Access Journals (Sweden)

Cupisti A

2013-10-01

Full Text Available Adamasco Cupisti,1 Maurizio Gallieni,2 Maria Antonietta Rizzo,2 Stefania Caria,3 Mario Meola,4 Piergiorgio Bolasco31Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy; 2Nephrology and Dialysis Unit, San Carlo Borromeo Hospital, Milan, Italy; 3Territorial Department of Nephrology and Dialysis, ASL Cagliari, Italy; 4Sant'Anna School of Advanced Studies, University of Pisa, Pisa, ItalyAbstract: Prevention and correction of hyperphosphatemia is a major goal of chronic kidney disease–mineral and bone disorder (CKD–MBD management, achievable through avoidance of a positive phosphate balance. To this aim, optimal dialysis removal, careful use of phosphate binders, and dietary phosphate control are needed to optimize the control of phosphate balance in well-nourished patients on a standard three-times-a-week hemodialysis schedule. Using a mixed diffusive–convective hemodialysis tecniques, and increasing the number and/or the duration of dialysis tecniques are all measures able to enhance phosphorus (P mass removal through dialysis. However, dialytic removal does not equal the high P intake linked to the high dietary protein requirement of dialysis patients; hence, the use of intestinal P binders is mandatory to reduce P net intestinal absorption. Unfortunately, even a large dose of P binders is able to bind approximately 200–300 mg of P on a daily basis, so it is evident that their efficacy is limited in the case of an uncontrolled dietary P load. Hence, limitation of dietary P intake is needed to reach the goal of neutral phosphate balance in dialysis, coupled to an adequate protein intake. To this aim, patients should be informed and educated to avoid foods that are naturally rich in phosphate and also processed food with P-containing preservatives. In addition, patients should preferentially choose food with a low P-to-protein ratio. For example, patients could choose egg white or protein from a vegetable source

Binding of ATP by pertussis toxin and isolated toxin subunits

International Nuclear Information System (INIS)

Hausman, S.Z.; Manclark, C.R.; Burns, D.L.

1990-01-01

The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of [ 3 H]ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of [ 3 H]ATP to pertussis toxin in a competitive manner; however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of [ 3 H]ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site

Binding of ATP by pertussis toxin and isolated toxin subunits

Energy Technology Data Exchange (ETDEWEB)

Hausman, S.Z.; Manclark, C.R.; Burns, D.L. (Center for Biologics Evaluation and Research, Bethesda, MD (USA))

1990-07-03

The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of ({sup 3}H)ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of ({sup 3}H)ATP to pertussis toxin in a competitive manner; however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of ({sup 3}H)ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site.

Calcium-phosphate-osteopontin particles for caries control

DEFF Research Database (Denmark)

Schlafer, Sebastian

Oftentimes caries lesions develop in protected sites that are difficult to access by self-performed mechanical tooth cleaning. At present, there is a growing interest in chemical adjuncts to mechanical procedures of oral hygiene that aim at biofilm control rather than biofilm eradication. Calcium......-phosphate-osteopontin particles are a new promising therapeutic approach to caries control. They are designed to bind to dental biofilms and interfere with biofilm build-up, lowering the bacterial burden on the tooth surface without affecting bacterial viability in the oral cavity. Moreover, they dissolve when pH in the biofilm...... drops to 6 or below and release buffering phosphate ions that stabilize biofilm pH above the critical level for enamel dissolution. With that twofold approach, calcium-phosphate-osteopontin particles may make a relevant contribution to clinical caries control....

Steady state kinetic model for the binding of substrates and allosteric effectors to Escherichia coli phosphoribosyl-diphosphate synthase

DEFF Research Database (Denmark)

Willemoës, Martin; Hove-Jensen, Bjarne; Larsen, Sine

2000-01-01

A steady state kinetic investigation of the Pi activation of 5-phospho-D-ribosyl α-1-diphosphate synthase from Escherichia coli suggests that Pi can bind randomly to the enzyme either before or after an ordered addition of free Mg2+ and substrates. Unsaturation with ribose 5-phosphate increased...... the apparent cooperativity of Pi activation. At unsaturating Pi concentrations partial substrate inhibition by ribose 5-phosphate was observed. Together these results suggest that saturation of the enzyme with Pi directs the subsequent ordered binding of Mg2+ and substrates via a fast pathway, whereas...... saturation with ribose 5-phosphate leads to the binding of Mg2+ and substrates via a slow pathway where Pi binds to the enzyme last. The random mechanism for Pi binding was further supported by studies with competitive inhibitors of Mg2+, MgATP, and ribose 5-phosphate that all appeared noncompetitive when...

Structural basis for phosphatidylinositol-phosphate biosynthesis

Science.gov (United States)

Clarke, Oliver B.; Tomasek, David; Jorge, Carla D.; Dufrisne, Meagan Belcher; Kim, Minah; Banerjee, Surajit; Rajashankar, Kanagalaghatta R.; Shapiro, Lawrence; Hendrickson, Wayne A.; Santos, Helena; Mancia, Filippo

2015-10-01

Phosphatidylinositol is critical for intracellular signalling and anchoring of carbohydrates and proteins to outer cellular membranes. The defining step in phosphatidylinositol biosynthesis is catalysed by CDP-alcohol phosphotransferases, transmembrane enzymes that use CDP-diacylglycerol as donor substrate for this reaction, and either inositol in eukaryotes or inositol phosphate in prokaryotes as the acceptor alcohol. Here we report the structures of a related enzyme, the phosphatidylinositol-phosphate synthase from Renibacterium salmoninarum, with and without bound CDP-diacylglycerol to 3.6 and 2.5 Å resolution, respectively. These structures reveal the location of the acceptor site, and the molecular determinants of substrate specificity and catalysis. Functional characterization of the 40%-identical ortholog from Mycobacterium tuberculosis, a potential target for the development of novel anti-tuberculosis drugs, supports the proposed mechanism of substrate binding and catalysis. This work therefore provides a structural and functional framework to understand the mechanism of phosphatidylinositol-phosphate biosynthesis.

How Native and Alien Metal Cations Bind ATP: Implications for Lithium as a Therapeutic Agent

Science.gov (United States)

Dudev, Todor; Grauffel, Cédric; Lim, Carmay

2017-02-01

Adenosine triphosphate (ATP), the major energy currency of the cell, exists in solution mostly as ATP-Mg. Recent experiments suggest that Mg2+ interacts with the highly charged ATP triphosphate group and Li+ can co-bind with the native Mg2+ to form ATP-Mg-Li and modulate the neuronal purine receptor response. However, it is unclear how the negatively charged ATP triphosphate group binds Mg2+ and Li+ (i.e. which phosphate group(s) bind Mg2+/Li+) and how the ATP solution conformation depends on the type of metal cation and the metal-binding mode. Here, we reveal the preferred ATP-binding mode of Mg2+/Li+ alone and combined: Mg2+ prefers to bind ATP tridentately to each of the three phosphate groups, but Li+ prefers to bind bidentately to the terminal two phosphates. We show that the solution ATP conformation depends on the cation and its binding site/mode, but it does not change significantly when Li+ binds to Mg2+-loaded ATP. Hence, ATP-Mg-Li, like Mg2+-ATP, can fit in the ATP-binding site of the host enzyme/receptor, activating specific signaling pathways.

Reducing the cadmium content of crude phosphates and mineral fertilizers

Energy Technology Data Exchange (ETDEWEB)

Plessen, H von; Schimmel, G

1987-10-01

Crude sedimentary phosphates generally contain cadmium together with traces of other heavy metals. These Cd traces generally end up in fertilizers produced from the crude phosphates. Processes have therefore been developed to separate the Cd from the crude phosphate or from the crude phosphoric acids arising therefrom as intermediates. In this way, the Cd content of the crude phosphate can be reduced to less the 10% of its original value, and to 50% thereof by extractive treatment with acidic calcium nitrate solution. Older calcination processes for crude phosphate have been improved to give residual Cd contents of 10 to 50% at temperatures of 800 to 1000/sup 0/C. Cadmium can be removed almost quantitatively from crude phosphate by means of dialkyl dithiophosphoric acid esters by extraction, binding to adsorbents, or ion flotation. Cadmium can be extracted from crude acids in high yield by long-chained amines. After partial neutralization of the crude acids, precipitation as cadmium sulphide is also possible.

Specificity of cellular DNA-binding sites of microbial populations in a Florida reservoir

International Nuclear Information System (INIS)

Paul, J.H.; Pichard, S.L.

1989-01-01

The substrate specificity of the DNA-binding mechanism(s) of bacteria in a Florida reservoir was investigated in short- and long-term uptake studies with radiolabeled DNA and unlabeled competitors. Thymine oligonucleotides ranging in size from 2 base pairs to 19 to 24 base pairs inhibited DNA binding in 20-min incubations by 43 to 77%. Deoxynucleoside monophosphates, thymidine, and thymine had little effect on short-term DNA binding, although several of these compounds inhibited the uptake of the radiolabel from DNA in 4-h incubations. Inorganic phosphate and glucose-1-phosphate inhibited neither short- nor long-term binding of [ 3 H]- or [ 32 P]DNA, indicating that DNA was not utilized as a phosphorous source in this reservoir. RNA inhibited both short- and long-term radiolabeled DNA uptake as effectively as unlabeled DNA. Collectively these results indicate that aquatic bacteria possess a generalized nuclei acid uptake/binding mechanism specific for compounds containing phosphodiester bonds and capable of recognizing oligonucleotides as short as dinucleotides. This binding site is distinct from nucleoside-, nucleotide-, phosphomonoester-, and inorganic phosphate-binding sites. Such a nucleic acid-binding mechanism may have evolved for the utilization of extracellular DNA (and perhaps RNA), which is abundant in many marine and freshwater environments

Sucrose fermentation by Saccharomyces cerevisiae lacking hexose transport.

Science.gov (United States)

Batista, Anderson S; Miletti, Luiz C; Stambuk, Boris U

2004-01-01

Sucrose is the major carbon source used by Saccharomyces cerevisiae during production of baker's yeast, fuel ethanol and several distilled beverages. It is generally accepted that sucrose fermentation proceeds through extracellular hydrolysis of the sugar, mediated by the periplasmic invertase, producing glucose and fructose that are transported into the cells and metabolized. In the present work we analyzed the contribution to sucrose fermentation of a poorly characterized pathway of sucrose utilization by S. cerevisiae cells, the active transport of the sugar through the plasma membrane and its intracellular hydrolysis. A yeast strain that lacks the major hexose transporters (hxt1-hxt7 and gal2) is incapable of growing on or fermenting glucose or fructose. Our results show that this hxt-null strain is still able to ferment sucrose due to direct uptake of the sugar into the cells. Deletion of the AGT1 gene, which encodes a high-affinity sucrose-H(+) symporter, rendered cells incapable of sucrose fermentation. Since sucrose is not an inducer of the permease, expression of the AGT1 must be constitutive in order to allow growth of the hxt-null strain on sucrose. The molecular characterization of active sucrose transport and fermentation by S. cerevisiae cells opens new opportunities to optimize yeasts for sugarcane-based industrial processes.

Characterisation of the Aspergillus nidulans frA1 mutant: hexose phosphorylation and apparent lack of involvement of hexokinase in glucose repression.

NARCIS (Netherlands)

Ruijter, G.J.G.; Panneman, H.; Broeck, van den H.C.; Bennett, J.M.; Visser, J.

1996-01-01

Hexose phosphorylation was studied in Aspergillus nidulans wild-type and in a fructose non-utilising mutant (frA). The data indicate the presence of at least one hexokinase and one glucokinase in wild-type A. nidulans, while the frA1 mutant lacks hexokinase activity. The A. nidulans gene encoding

Dephosphorylation of microtubule-binding sites at the neurofilament-H tail domain by alkaline, acid, and protein phosphatases.

Science.gov (United States)

Hisanaga, S; Yasugawa, S; Yamakawa, T; Miyamoto, E; Ikebe, M; Uchiyama, M; Kishimoto, T

1993-06-01

The dephosphorylation-induced interaction of neurofilaments (NFs) with microtubules (MTs) was investigated by using several phosphatases. Escherichia coli alkaline and wheat germ acid phosphatases increased the electrophoretic mobility of NF-H and NF-M by dephosphorylation, and induced the binding of NF-H to MTs. The binding of NFs to MTs was observed only after the electrophoretic mobility of NF-H approached the exhaustively dephosphorylated level when alkaline phosphatase was used. The number of phosphate remaining when NF-H began to bind to MTs was estimated by measuring phosphate bound to NF-H. NF-H did not bind to MTs even when about 40 phosphates from the total of 51 had been removed by alkaline phosphatase. The removal of 6 further phosphates finally resulted in the association of NF-H with MTs. A similar finding, that the restricted phosphorylation sites in the NF-H tail domain, but not the total amount of phosphates, were important for binding to MTs, was also obtained with acid phosphatases. In contrast to alkaline and acid phosphatases, four classes of protein phosphatases (protein phosphatases 1, 2A, 2B, and 2C) were ineffective for shifting the electrophoretic mobility of NF proteins and for inducing the association of NFs to MTs.

Sublingual immunization with the phosphate-binding-protein (PstS) reduces oral colonization by Streptococcus mutans.

Science.gov (United States)

Ferreira, E L; Batista, M T; Cavalcante, R C M; Pegos, V R; Passos, H M; Silva, D A; Balan, A; Ferreira, L C S; Ferreira, R C C

2016-10-01

Bacterial ATP-binding cassette (ABC) transporters play a crucial role in the physiology and pathogenicity of different bacterial species. Components of ABC transporters have also been tested as target antigens for the development of vaccines against different bacterial species, such as those belonging to the Streptococcus genus. Streptococcus mutans is the etiological agent of dental caries, and previous studies have demonstrated that deletion of the gene encoding PstS, the substrate-binding component of the phosphate uptake system (Pst), reduced the adherence of the bacteria to abiotic surfaces. In the current study, we generated a recombinant form of the S. mutans PstS protein (rPstS) with preserved structural features, and we evaluated the induction of antibody responses in mice after sublingual mucosal immunization with a formulation containing the recombinant protein and an adjuvant derived from the heat-labile toxin from enterotoxigenic Escherichia coli strains. Mice immunized with rPstS exhibited systemic and secreted antibody responses, measured by the number of immunoglobulin A-secreting cells in draining lymph nodes. Serum antibodies raised in mice immunized with rPstS interfered with the adhesion of bacteria to the oral cavity of naive mice challenged with S. mutans. Similarly, mice actively immunized with rPstS were partially protected from oral colonization after challenge with the S. mutans NG8 strain. Therefore, our results indicate that S. mutans PstS is a potential target antigen capable of inducing specific and protective antibody responses after sublingual administration. Overall, these observations raise interesting perspectives for the development of vaccines to prevent dental caries. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Bulkiness or aromatic nature of tyrosine-143 of actin is important for the weak binding between F-actin and myosin-ADP-phosphate

Energy Technology Data Exchange (ETDEWEB)

Gomibuchi, Yuki [Graduate School of Science and Engineering, Teikyo University, Toyosatodai 1-1, Utsunomiya 320-8551 (Japan); Uyeda, Taro Q.P. [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562 (Japan); Wakabayashi, Takeyuki, E-mail: tw007@nasu.bio.teikyo-u.ac.jp [Graduate School of Science and Engineering, Teikyo University, Toyosatodai 1-1, Utsunomiya 320-8551 (Japan); Department of Judo Therapy, Faculty of Medical Technology, Teikyo University, Toyosatodai 1-1, Utsunomiya 320-8551 (Japan)

2013-11-29

) of the replaced amino acid molecule. Because 1/K{sub app} reflects the affinity of F-actin for the myosin–ADP-phosphate intermediate (M.ADP.Pi) through the weak binding, these data suggest that the bulkiness or the aromatic nature of the tyrosin-143 is important for the initial binding of the M.ADP.Pi intermediate with F-actin but not for later processes such as the phosphate release.

Reciprocal Regulation of GlnR and PhoP in Response to Nitrogen and Phosphate Limitations in Saccharopolyspora erythraea

Science.gov (United States)

Yao, Li-li

2015-01-01

Nitrogen and phosphate source sensing, uptake, and assimilation are essential for the growth and development of microorganisms. In this study, we demonstrated that SACE_6965 encodes the phosphate regulator PhoP, which controls the transcription of genes involved in phosphate metabolism in the erythromycin-producing Saccharopolyspora erythraea. We found that PhoP and the nitrogen regulator GlnR both regulate the transcription of glnR as well as other nitrogen metabolism-related genes. Interestingly, both GlnR- and PhoP-binding sites were identified in the phoP promoter region. Unlike the nonreciprocal regulation of GlnR and PhoP observed in Streptomyces coelicolor and Streptomyces lividans, GlnR negatively controls the transcription of the phoP gene in S. erythraea. This suggests that GlnR directly affects phosphate metabolism and demonstrates that the cross talk between GlnR and PhoP is reciprocal. Although GlnR and PhoP sites in the glnR and phoP promoter regions are located in close proximity to one another (separated by only 2 to 4 bp), the binding of both regulators to their respective region was independent and noninterfering. These results indicate that two regulators could separately bind to their respective binding sites and control nitrogen and phosphate metabolism in response to environmental changes. The reciprocal cross talk observed between GlnR and PhoP serves as a foundation for understanding the regulation of complex primary and secondary metabolism in antibiotic-producing actinomycetes. PMID:26519391

Identification of human Phosphatidyl Inositol 5-Phosphate 4-Kinase as an RNA binding protein that is imported into Plasmodium falciparum.

Science.gov (United States)

Vindu, Arya; Dandewad, Vishal; Seshadri, Vasudevan

2018-04-06

Plasmodium falciparum is a causative agent for malaria and has a complex life cycle in human and mosquito hosts. Translation repression of specific set of mRNA has been reported in gametocyte stages of this parasite. A conserved element present in the 3'UTR of some of these transcripts was identified. Biochemical studies have identified components of the RNA storage and/or translation inhibitor complex but it is not yet clear how the complex is specifically recruited on the RNA targeted for translation regulation. We used the 3'UTR region of translationally regulated transcripts to identify Phosphatidyl-inositol 5-phosphate 4-kinase (PIP4K2A) as the protein that associates with these RNAs. We further show that recombinant PIP4K2A has the RNA binding activity and can associate specifically with Plasmodium 3'UTR RNAs. Immunostainings show that hPIP4K2A is imported into the Plasmodium parasite from RBC. These results identify a novel RNA binding role for PIP4K2A that may play a role in Plasmodium propagation. Copyright © 2018 Elsevier Inc. All rights reserved.

Palmitate and stearate binding to human serum albumin. Determination of relative binding constants

DEFF Research Database (Denmark)

Vorum, H; Fisker, K; Honoré, B

1997-01-01

Multiple binding equilibria of two apparently insoluble ligands, palmitate and stearate, to defatted human serum albumin were studied in a 66 mM sodium phosphate buffer (pH 7.4) at 37 degrees C, by determination of dialytic exchange rates of ligands among identical equilibrium solutions. The expe...

Enhanced hexose fermentation by Saccharomyces cerevisiae through integration of stoichiometric modeling and genetic screening.

Science.gov (United States)

Quarterman, Josh; Kim, Soo Rin; Kim, Pan-Jun; Jin, Yong-Su

2015-01-20

In order to determine beneficial gene deletions for ethanol production by the yeast Saccharomyces cerevisiae, we performed an in silico gene deletion experiment based on a genome-scale metabolic model. Genes coding for two oxidative phosphorylation reactions (cytochrome c oxidase and ubiquinol cytochrome c reductase) were identified by the model-based simulation as potential deletion targets for enhancing ethanol production and maintaining acceptable overall growth rate in oxygen-limited conditions. Since the two target enzymes are composed of multiple subunits, we conducted a genetic screening study to evaluate the in silico results and compare the effect of deleting various portions of the respiratory enzyme complexes. Over two-thirds of the knockout mutants identified by the in silico study did exhibit experimental behavior in qualitative agreement with model predictions, but the exceptions illustrate the limitation of using a purely stoichiometric model-based approach. Furthermore, there was a substantial quantitative variation in phenotype among the various respiration-deficient mutants that were screened in this study, and three genes encoding respiratory enzyme subunits were identified as the best knockout targets for improving hexose fermentation in microaerobic conditions. Specifically, deletion of either COX9 or QCR9 resulted in higher ethanol production rates than the parental strain by 37% and 27%, respectively, with slight growth disadvantages. Also, deletion of QCR6 led to improved ethanol production rate by 24% with no growth disadvantage. The beneficial effects of these gene deletions were consistently demonstrated in different strain backgrounds and with four common hexoses. The combination of stoichiometric modeling and genetic screening using a systematic knockout collection was useful for narrowing a large set of gene targets and identifying targets of interest. Copyright © 2014 Elsevier B.V. All rights reserved.

Fragmentation Pathways of Lithiated Hexose Monosaccharides

Science.gov (United States)

Abutokaikah, Maha T.; Frye, Joseph W.; Tschampel, John; Rabus, Jordan M.; Bythell, Benjamin J.

2018-05-01

We characterize the primary fragmentation reactions of three isomeric lithiated D-hexose sugars (glucose, galactose, and mannose) utilizing tandem mass spectrometry, regiospecific labeling, and theory. We provide evidence that these three isomers populate similar fragmentation pathways to produce the abundant cross-ring cleavage peaks (0,2A1 and 0,3A1). These pathways are highly consistent with the prior literature (Hofmeister et al. J. Am. Chem. Soc. 113, 5964-5970, 1991, Bythell et al. J. Am. Soc. Mass Spectrom. 28, 688-703, 2017, Rabus et al. Phys. Chem. Chem. Phys. 19, 25643-25652, 2017) and the present labeling data. However, the structure-specific energetics and rate-determining steps of these reactions differ as a function of precursor sugar and anomeric configuration. The lowest energy water loss pathways involve loss of the anomeric oxygen to furnish B1 ions. For glucose and galactose, the lithiated α-anomers generate ketone structures at C2 in a concerted reaction involving a 1,2-migration of the C2-H to the anomeric carbon (C1). In contrast, the β-anomers are predicted to form 1,3-anhydroglucose/galactose B1 ion structures. Initiation of the water loss reactions from each anomeric configuration requires distinct reactive conformers, resulting in different product ion structures. Inversion of the stereochemistry at C2 has marked consequences. Both lithiated mannose forms expel water to form 1,2-anhydromannose B1 ions with the newly formed epoxide group above the ring. Additionally, provided water loss is not instantaneous, the α-anomer can also isomerize to generate a ketone structure at C2 in a concerted reaction involving a 1,2-migration of the C2-H to C1. This product is indistinguishable to that from α-glucose. The energetics and interplay of these pathways are discussed. [Figure not available: see fulltext.

sphingosine-1-phosphate transport and its role in immunology

NARCIS (Netherlands)

Reitsema, V.; Bouma, Hjalmar; Kok, Jan

2014-01-01

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite with many important functions in cellular and systemic physiology, including the immune system. As it cannot traverse the membrane, it is exported from cells by transporters. Several members of the ATP-binding cassette (ABC) transporter

Engineering Potato Starch with a Higher Phosphate Content.

Directory of Open Access Journals (Sweden)

Xuan Xu

Full Text Available Phosphate esters are responsible for valuable and unique functionalities of starch for industrial applications. Also in the cell phosphate esters play a role in starch metabolism, which so far has not been well characterized in storage starch. Laforin, a human enzyme composed of a carbohydrate-binding module and a dual-specificity phosphatase domain, is involved in the dephosphorylation of glycogen. To modify phosphate content and better understand starch (dephosphorylation in storage starch, laforin was engineered and introduced into potato (cultivar Kardal. Interestingly, expression of an (engineered laforin in potato resulted in significantly higher phosphate content of starch, and this result was confirmed in amylose-free potato genetic background (amf. Modified starches exhibited altered granule morphology and size compared to the control. About 20-30% of the transgenic lines of each series showed red-staining granules upon incubation with iodine, and contained higher phosphate content than the blue-stained starch granules. Moreover, low amylose content and altered gelatinization properties were observed in these red-stained starches. Principle component and correlation analysis disclosed a complex correlation between starch composition and starch physico-chemical properties. Ultimately, the expression level of endogenous genes involved in starch metabolism was analysed, revealing a compensatory response to the decrease of phosphate content in potato starch. This study provides a new perspective for engineering starch phosphate content in planta by making use of the compensatory mechanism in the plant itself.

Coordination chemistry of sugar-phosphate complexes with palladium(II), rhenium(V) and zinc(II)

Energy Technology Data Exchange (ETDEWEB)

Steinborn, Christian Martin

2013-05-21

As described before, some studies dealing with coordination chemistry of sugar phosphates are available but no analogous complexes of Zn{sup II} have been investigated yet. The primary goal of this work is, therefore, to fill this gap. In order to stay close to the active sites of enzymes such as class-II-aldolase, the simple metal fragment Zn{sup II}(dien) is used. NMR spectroscopy is used primarily as analytical method since it enables the investigation of both complex equilibria in solution and pH dependence of metal-binding sites. Since this approach is challenging due to the fast metal-ligand exchange and the absence of CIS values, it is necessary to improve the significance of NMR data collected from sugar-phosphate complexes with Zn{sup II}. Hence, further experiments are performed with molecules similar to sugar phosphates such as reducing and methylated sugars or polyols. Beside NMR spectroscopy, crystal-structure analysis will be used to get more detailed information about the binding pattern of the complexes. Additionally, sugar-phosphate complexes of Pd{sup II} are investigated. Further experiments are conducted, on the one hand, to synthesise more sugarphosphate complexes with ReVON2 fragments, and, on the other hand, to grow crystals confirming the theory about mixed sugar-core-phosphate chelation.

Thermodynamics of the hydrolysis reactions of α-D-galactose 1-phosphate, sn-glycerol 3-phosphate, 4-nitrophenyl phosphate, phosphocreatine, and 3-phospho-D-glycerate

International Nuclear Information System (INIS)

Goldberg, Robert N.; Lang, Brian E.; Lo, Catherine; Ross, David J.; Tewari, Yadu B.

2009-01-01

Microcalorimetry, high-performance liquid chromatography (h.p.l.c.), and an enzymatic assay have been used to conduct a thermodynamic investigation of five phosphate hydrolysis reactions: {α-D-galactose 1-phosphate(aq) + H 2 O(l) = D-galactose(aq) + orthophosphate(aq)} (1), {sn-glycerol 3-phosphate(aq) + H 2 O(l) = glycerol(aq) + orthophosphate(aq)} (2), {4-nitrophenyl phosphate(aq) + H 2 O(l) = 4-nitrophenol(aq) + orthophosphate(aq)} (3), {phosphocreatine(aq) + H 2 O(l) = creatine(aq) + orthophosphate(aq)} (4), and {3-phospho-D-glycerate(aq) + H 2 O(l) = D-glycerate(aq) + orthophosphate(aq)} (5). Calorimetrically determined enthalpies of reaction Δ r H(cal) were measured for reactions (1)-(5) and the apparent equilibrium constant K' was measured for reaction (2). The pKs and standard enthalpies of reaction Δ r H 0 for the H + and Mg 2+ binding reactions of the reactants and products in the aforementioned reactions were obtained either from the literature or by estimation. A chemical equilibrium model was then used to calculate standard equilibrium constants K and standard enthalpies of reaction Δ r H 0 for chemical reference reactions that correspond to the overall biochemical reactions that were studied experimentally. Property values from the literature and thermodynamic network calculations were used to obtain values of the equilibrium constants for the chemical reference reactions that correspond to the overall biochemical reactions (1). These values were compared with other results from the literature and also correlated with structural features. The results obtained in this study can be used in the chemical equilibrium model to calculate values of K', the standard apparent Gibbs free energy changes Δ r G '0 , the standard apparent enthalpy changes Δ r H '0 , changes in binding of the proton Δ r N(H + ), and the position of equilibrium for the overall biochemical reactions considered in this study over a reasonably wide range of temperature, pH, p

Expression Patterns, Activities and Carbohydrate-Metabolizing Regulation of Sucrose Phosphate Synthase, Sucrose Synthase and Neutral Invertase in Pineapple Fruit during Development and Ripening

Science.gov (United States)

Zhang, Xiu-Mei; Wang, Wei; Du, Li-Qing; Xie, Jiang-Hui; Yao, Yan-Li; Sun, Guang-Ming

2012-01-01

Differences in carbohydrate contents and metabolizing-enzyme activities were monitored in apical, medial, basal and core sections of pineapple (Ananas comosus cv. Comte de paris) during fruit development and ripening. Fructose and glucose of various sections in nearly equal amounts were the predominant sugars in the fruitlets, and had obvious differences until the fruit matured. The large rise of sucrose/hexose was accompanied by dramatic changes in sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) activities. By contrast, neutral invertase (NI) activity may provide a mechanism to increase fruit sink strength by increasing hexose concentrations. Furthermore, two cDNAs of Ac-sps (accession no. GQ996582) and Ac-ni (accession no. GQ996581) were first isolated from pineapple fruits utilizing conserved amino-acid sequences. Homology alignment reveals that the amino acid sequences contain some conserved function domains. Transcription expression analysis of Ac-sps, Ac-susy and Ac-ni also indicated distinct patterns related to sugar accumulation and composition of pineapple fruits. It suggests that differential expressions of multiple gene families are necessary for sugar metabolism in various parts and developmental stages of pineapple fruit. A cycle of sucrose breakdown in the cytosol of sink tissues could be mediated through both Ac-SuSy and Ac-NI, and Ac-NI could be involved in regulating crucial steps by generating sugar signals to the cells in a temporally and spatially restricted fashion. PMID:22949808

Lack of conventional oxygen-linked proton and anion binding sites does not impair allosteric regulation of oxygen binding in dwarf caiman hemoglobin

Science.gov (United States)

Fago, Angela; Malte, Hans; Storz, Jay F.; Gorr, Thomas A.

2013-01-01

In contrast to other vertebrate hemoglobins (Hbs) whose high intrinsic O2 affinities are reduced by red cell allosteric effectors (mainly protons, CO2, organic phosphates, and chloride ions), crocodilian Hbs exhibit low sensitivity to organic phosphates and high sensitivity to bicarbonate (HCO3−), which is believed to augment Hb-O2 unloading during diving and postprandial alkaline tides when blood HCO3− levels and metabolic rates increase. Examination of α- and β-globin amino acid sequences of dwarf caiman (Paleosuchus palpebrosus) revealed a unique combination of substitutions at key effector binding sites compared with other vertebrate and crocodilian Hbs: β82Lys→Gln, β143His→Val, and β146His→Tyr. These substitutions delete positive charges and, along with other distinctive changes in residue charge and polarity, may be expected to disrupt allosteric regulation of Hb-O2 affinity. Strikingly, however, P. palpebrosus Hb shows a strong Bohr effect, and marked deoxygenation-linked binding of organic phosphates (ATP and DPG) and CO2 as carbamate (contrasting with HCO3− binding in other crocodilians). Unlike other Hbs, it polymerizes to large complexes in the oxygenated state. The highly unusual properties of P. palpebrosus Hb align with a high content of His residues (potential sites for oxygenation-linked proton binding) and distinctive surface Cys residues that may form intermolecular disulfide bridges upon polymerization. On the basis of its singular properties, P. palpebrosus Hb provides a unique opportunity for studies on structure-function coupling and the evolution of compensatory mechanisms for maintaining tissue O2 delivery in Hbs that lack conventional effector-binding residues. PMID:23720132

Compartmentation of glycogen metabolism revealed from 13C isotopologue distributions

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Marin de Mas Igor

2011-10-01

Full Text Available Abstract Background Stable isotope tracers are used to assess metabolic flux profiles in living cells. The existing methods of measurement average out the isotopic isomer distribution in metabolites throughout the cell, whereas the knowledge of compartmental organization of analyzed pathways is crucial for the evaluation of true fluxes. That is why we accepted a challenge to create a software tool that allows deciphering the compartmentation of metabolites based on the analysis of average isotopic isomer distribution. Results The software Isodyn, which simulates the dynamics of isotopic isomer distribution in central metabolic pathways, was supplemented by algorithms facilitating the transition between various analyzed metabolic schemes, and by the tools for model discrimination. It simulated 13C isotope distributions in glucose, lactate, glutamate and glycogen, measured by mass spectrometry after incubation of hepatocytes in the presence of only labeled glucose or glucose and lactate together (with label either in glucose or lactate. The simulations assumed either a single intracellular hexose phosphate pool, or also channeling of hexose phosphates resulting in a different isotopic composition of glycogen. Model discrimination test was applied to check the consistency of both models with experimental data. Metabolic flux profiles, evaluated with the accepted model that assumes channeling, revealed the range of changes in metabolic fluxes in liver cells. Conclusions The analysis of compartmentation of metabolic networks based on the measured 13C distribution was included in Isodyn as a routine procedure. The advantage of this implementation is that, being a part of evaluation of metabolic fluxes, it does not require additional experiments to study metabolic compartmentation. The analysis of experimental data revealed that the distribution of measured 13C-labeled glucose metabolites is inconsistent with the idea of perfect mixing of hexose

Phosphate-bonded composite electrodes for hydrogen evolution

Energy Technology Data Exchange (ETDEWEB)

Potvin, E.; Menard, H.; Lalancette, J.M. (Sherbrooke Univ., PQ (Canada). Dept. de Chimie); Brossard, L. (Institut de Recherche d' Hydro-Quebec, Varennes, PQ (Canada))

1990-03-01

A new process of cementing metallic powders to produce high surface area cathodes for alkaline water electrolysis is described. The binding compound is a tridimensional polymer of aluminium phosphate (AlPO{sub 4}). Phosphate-bonded composite electrodes give a low-polarization performance for hydrogen evolution in 1 M KOH aqueous solution in the case of 95wt% Pt and 98wt%Ni. When electrode materials are prepared with nickel powder, the electrocatalytic activity for the hydrogen evolution reaction, the chemical stability and the electrical conductivity depend on the Ni content and morphology of the electrode. The best performance and chemical stability with Ni as the starting material are obtained for spiky filamentary particles produced by the decomposition of nickel carbonyl. (author).

The overexpressed human 46-kDa mannose 6-phosphate receptor mediates endocytosis and sorting of β-glucuronidase

International Nuclear Information System (INIS)

Watanabe, H.; Grubb, J.H.; Sly, W.S.

1990-01-01

The authors studied the function of the human small (46-kDa) mannose 6-phosphate receptor (SMPR) in transfected mouse L cells that do not express the larger insulin-like growth factor II/mannose 6-phosphate receptor. Cells overexpressing human SMPR were studied for enzyme binding to cell surface receptors, for binding to intracellular receptors in permeabilized cells, and for receptor-mediated endocytosis of recombinant human β-glucuronidase. Specific binding to human SMPR in permeabilized cells showed a pH optimum between pH 6.0 and pH 6.5. Binding was significant in the present of EDTA but was enhanced by added divalent cations. Up to 2.3% of the total functional receptor could be detected on the cell surface by enzyme binding. They present experiments showing that at very high levels of overexpression, and at pH 6.5, human SMPR mediated the endocytosis of β-glucuronidase. At pH 7.5, the rate of endocytosis was only 14% the rate seen at pH 6.5. Cells overexpressing human SMPR also showed reduced secretion of newly synthesized β-glucuronidase when compared to cells transfected with vector only, suggesting that overexpressed human SMPR can participate in sorting of newly synthesized β-glucuronidase and partially correct the sorting defect in mouse L cells that do not express the insulin-like growth factor II/mannose 6-phosphate receptor

On calculation of the electrostatic potential of a phosphatidylinositol phosphate-containing phosphatidylcholine lipid membrane accounting for membrane dynamics.

Directory of Open Access Journals (Sweden)

Jonathan C Fuller

Full Text Available Many signaling events require the binding of cytoplasmic proteins to cell membranes by recognition of specific charged lipids, such as phosphoinositol-phosphates. As a model for a protein-membrane binding site, we consider one charged phosphoinositol phosphate (PtdIns(3P embedded in a phosphatidylcholine bilayer. As the protein-membrane binding is driven by electrostatic interactions, continuum solvent models require an accurate representation of the electrostatic potential of the phosphoinositol phosphate-containing membrane. We computed and analyzed the electrostatic potentials of snapshots taken at regular intervals from molecular dynamics simulations of the bilayer. We observe considerable variation in the electrostatic potential of the bilayer both along a single simulation and between simulations performed with the GAFF or CHARMM c36 force fields. However, we find that the choice of GAFF or CHARMM c36 parameters has little effect on the electrostatic potential of a given configuration of the bilayer with a PtdIns(3P embedded in it. From our results, we propose a remedian averaging method for calculating the electrostatic potential of a membrane system that is suitable for simulations of protein-membrane binding with a continuum solvent model.

Effect of altitude on oxygen binding by hemoglobin and on organic phosphate levels

Science.gov (United States)

Lenfant, Claude; Torrance, John; English, Eugenia; Finch, Clement A.; Reynafarje, Cesar; Ramos, Jose; Faura, Jose

1968-01-01

The relationship between oxygen dissociation and 2,3-diphosphoglycerate (2,3-DPG) in the red cell has been studied in subjects moving from low to high altitude and vice versa. Within 24 hr following the change in altitude there was a change in hemoglobin affinity for oxygen; this modification therefore represents an important rapid adaptive mechanism to anoxia. A parallel change occurred in the organic phosphate content of the red cell. While this study does not provide direct evidence of a cause-effect relationship, the data strongly suggest that with anoxia, the observed rise in organic phosphate content of the red cell is responsible for increased availability of oxygen to tissues. Images PMID:5725278

HIV-1 Nef binds with human GCC185 protein and regulates mannose 6 phosphate receptor recycling

Energy Technology Data Exchange (ETDEWEB)

Kumar, Manjeet; Kaur, Supinder; Nazir, Aamir; Tripathi, Raj Kamal, E-mail: rajkamalcdri@gmail.com

2016-05-20

HIV-1 Nef modulates cellular function that enhances viral replication in vivo which culminate into AIDS pathogenesis. With no enzymatic activity, Nef regulates cellular function through host protein interaction. Interestingly, trans-cellular introduction of recombinant Nef protein in Caenorhabditis elegans results in AIDS like pathogenesis which might share common pathophysiology because the gene sequence of C. elegans and humans share considerable homology. Therefore employing C. elegans based initial screen complemented with sequence based homology search we identified GCC185 as novel host protein interacting with HIV-1 Nef. The detailed molecular characterization revealed N-terminal EEEE{sub 65} acidic domain of Nef as key region for interaction. GCC185 is a tethering protein that binds with Rab9 transport vesicles. Our results show that Nef-GCC185 interaction disrupts Rab9 interaction resulting in delocalization of CI-MPR (cation independent Mannose 6 phosphate receptor) resulting in elevated secretion of hexosaminidase. In agreement with this, our studies identified novel host GCC185 protein that interacts with Nef EEEE65 acidic domain interfering GCC185-Rab9 vesicle membrane fusion responsible for retrograde vesicular transport of CI-MPR from late endosomes to TGN. In light of existing report suggesting critical role of Nef-GCC185 interaction reveals valuable mechanistic insights affecting specific protein transport pathway in docking of late endosome derived Rab9 bearing transport vesicle at TGN elucidating role of Nef during viral pathogenesis. -- Highlights: •Nef, an accessory protein of HIV-1 interacts with host factor and culminates into AIDS pathogenesis. •Using Caenorhabditis elegans based screen system, novel Nef interacting cellular protein GCC185 was identified. •Molecular characterization of Nef and human protein GCC185 revealed Nef EEEE{sub 65} key region interacted with full length GCC185. •Nef impeded the GCC185-Rab 9 interaction and

The 1.1 Å resolution structure of a periplasmic phosphate-binding protein from Stenotrophomonas maltophilia: a crystallization contaminant identified by molecular replacement using the entire Protein Data Bank.

Science.gov (United States)

Keegan, Ronan; Waterman, David G; Hopper, David J; Coates, Leighton; Taylor, Graham; Guo, Jingxu; Coker, Alun R; Erskine, Peter T; Wood, Steve P; Cooper, Jonathan B

2016-08-01

During efforts to crystallize the enzyme 2,4-dihydroxyacetophenone dioxygenase (DAD) from Alcaligenes sp. 4HAP, a small number of strongly diffracting protein crystals were obtained after two years of crystal growth in one condition. The crystals diffracted synchrotron radiation to almost 1.0 Å resolution and were, until recently, assumed to be formed by the DAD protein. However, when another crystal form of this enzyme was eventually solved at lower resolution, molecular replacement using this new structure as the search model did not give a convincing solution with the original atomic resolution data set. Hence, it was considered that these crystals might have arisen from a protein impurity, although molecular replacement using the structures of common crystallization contaminants as search models again failed. A script to perform molecular replacement using MOLREP in which the first chain of every structure in the PDB was used as a search model was run on a multi-core cluster. This identified a number of prokaryotic phosphate-binding proteins as scoring highly in the MOLREP peak lists. Calculation of an electron-density map at 1.1 Å resolution based on the solution obtained with PDB entry 2q9t allowed most of the amino acids to be identified visually and built into the model. A BLAST search then indicated that the molecule was most probably a phosphate-binding protein from Stenotrophomonas maltophilia (UniProt ID B4SL31; gene ID Smal_2208), and fitting of the corresponding sequence to the atomic resolution map fully corroborated this. Proteins in this family have been linked to the virulence of antibiotic-resistant strains of pathogenic bacteria and with biofilm formation. The structure of the S. maltophilia protein has been refined to an R factor of 10.15% and an Rfree of 12.46% at 1.1 Å resolution. The molecule adopts the type II periplasmic binding protein (PBP) fold with a number of extensively elaborated loop regions. A fully dehydrated phosphate

Effect of humic acid preloading on phosphate adsorption onto zirconium-modified zeolite.

Science.gov (United States)

Lin, Jianwei; Zhang, Zhe; Zhan, Yanhui

2017-05-01

A zirconium-modified zeolite (ZrMZ) was prepared, and then, humic acid (HA) was immobilized on the ZrMZ surface to prepare HA-loaded ZrMZ (HA-ZrMZ). The obtained ZrMZ and HA-ZrMZ were characterized by energy dispersive X-ray spectroscopy, elemental analyzer, N 2 adsorption/desorption isotherms, pH at the point of zero charge, and X-ray photoelectron spectroscopy. The adsorption characteristics of phosphate on ZrMZ and HA-ZrMZ were comparatively investigated in batch mode. The adsorption mechanism of phosphate on ZrMZ and HA-ZrMZ was investigated by ionic strength effect and 31 P nuclear magnetic resonance. The mechanism for phosphate adsorption onto ZrMZ was the formation of inner-sphere phosphate complexes at the solid/solution interface. The preloading of HA on ZrMZ reduced the phosphate adsorption capacity, and the more the HA loading amount, the lower the phosphate adsorption capacity. However, the preloading of HA on ZrMZ did not change the phosphate adsorption mechanism; i.e., the formation of inner-sphere phosphate surface complexes was still responsible for the adsorption of phosphate on HA-ZrMZ. The decreased phosphate adsorption capacity for ZrMZ after HA coating could be attributed to the fact that the coating of HA on ZrMZ reduced the amount of binding active sites available for phosphate adsorption, changed the adsorbent surface charges, and reduced the specific surface areas and pore volumes of ZrMZ.

The RNA-Binding Site of Poliovirus 3C Protein Doubles as a Phosphoinositide-Binding Domain.

Science.gov (United States)

Shengjuler, Djoshkun; Chan, Yan Mei; Sun, Simou; Moustafa, Ibrahim M; Li, Zhen-Lu; Gohara, David W; Buck, Matthias; Cremer, Paul S; Boehr, David D; Cameron, Craig E

2017-12-05

Some viruses use phosphatidylinositol phosphate (PIP) to mark membranes used for genome replication or virion assembly. PIP-binding motifs of cellular proteins do not exist in viral proteins. Molecular-docking simulations revealed a putative site of PIP binding to poliovirus (PV) 3C protein that was validated using nuclear magnetic resonance spectroscopy. The PIP-binding site was located on a highly dynamic α helix, which also functions in RNA binding. Broad PIP-binding activity was observed in solution using a fluorescence polarization assay or in the context of a lipid bilayer using an on-chip, fluorescence assay. All-atom molecular dynamics simulations of the 3C protein-membrane interface revealed PIP clustering and perhaps PIP-dependent conformations. PIP clustering was mediated by interaction with residues that interact with the RNA phosphodiester backbone. We conclude that 3C binding to membranes will be determined by PIP abundance. We suggest that the duality of function observed for 3C may extend to RNA-binding proteins of other viruses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cation binding at the node of Ranvier: I. Localization of binding sites during development.

Science.gov (United States)

Zagoren, J C; Raine, C S; Suzuki, K

1982-06-17

Cations are known to bind to the node of Ranvier and the paranodal regions of myelinated fibers. The integrity of these specialized structures is essential for normal conduction. Sites of cation binding can be microscopically identified by the electrondense histochemical reaction product formed by the precipitate of copper sulfate/potassium ferrocyanide. This technique was used to study the distribution of cation binding during normal development of myelinating fibers. Sciatic nerves of C57B1 mice, at 1, 3, 5, 6, 7, 8, 9, 13, 16, 18, 24 and 30 days of age, were prepared for electron microscopy following fixation in phosphate-buffered 2.5% glutaraldehyde and 1% osmic acid, microdissection and incubation in phosphate-buffered 0.1 M cupric sulfate followed by 0.1 M potassium ferrocyanide. Localization of reaction product was studied by light and electron microscopy. By light microscopy, no reaction product was observed prior to 9 days of age. At 13 days, a few nodes and paranodes exhibited reaction product. This increased in frequency and intensity up to 30 days when almost all nodes or paranodes exhibited reaction product. Ultrastructurally, diffuse reaction product was first observed at 3 days of age in the axoplasm of the node, in the paranodal extracellular space of the terminal loops, in the Schwann cell proper and in the terminal loops of Schwann cell cytoplasm. When myelinated axons fulfilled the criteria for mature nodes, reaction product was no longer observed in the Schwann cell cytoplasm, while the intensity of reaction product in the nodal axoplasm and paranodal extracellular space of the terminal loops increased. Reaction product in the latter site appeared to be interrupted by the transverse bands. These results suggest that cation binding accompanies nodal maturity and that the Schwann cell may play a role in production or storage of the cation binding substance during myelinogenesis and development.

Oxygen binding to nitric oxide marked hemoglobin

International Nuclear Information System (INIS)

Louro, S.R.W.; Ribeiro, P.C.; Bemski, G.

1979-04-01

Electron spin resonance spectra of organic phosphate free human hemoglobin marked with nitric oxide at the sixth coordination position of one of the four hemes allow to observe the transition from the tense (T) to the relaxed (R) conformation, as a function of parcial oxygen pressure. The spectra are composites of contributions from α sub(T), α sub(R) and β chains spectra, showing the presence of only two conformations: T and R. In the absence of organic phosphates NO binds to α and β chains with the same probability, but in the presence of phosphates NO combines preferentially with α chains. The dissociation of NO proceeds at least an order of magnitude faster in T than in R configuration. (author) [pt

Stimulation of Suicidal Erythrocyte Death by Increased Extracellular Phosphate Concentrations

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Jakob Voelkl

2014-02-01

Full Text Available Background/Aim: Anemia in renal insufficiency results in part from impaired erythrocyte formation due to erythropoietin and iron deficiency. Beyond that, renal insufficiency enhances eryptosis, the suicidal erythrocyte death characterized by phosphatidylserine-exposure at the erythrocyte surface. Eryptosis may be stimulated by increase of cytosolic Ca2+-activity ([Ca2+]i. Several uremic toxins have previously been shown to stimulate eryptosis. Renal insufficiency is further paralleled by increase of plasma phosphate concentration. The present study thus explored the effect of phosphate on erythrocyte death. Methods: Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, and [Ca2+]i from Fluo3-fluorescence. Results: Following a 48 hours incubation, the percentage of phosphatidylserine exposing erythrocytes markedly increased as a function of extracellular phosphate concentration (from 0-5 mM. The exposure to 2 mM or 5 mM phosphate was followed by slight but significant hemolysis. [Ca2+]i did not change significantly up to 2 mM phosphate but significantly decreased at 5 mM phosphate. The effect of 2 mM phosphate on phosphatidylserine exposure was significantly augmented by increase of extracellular Ca2+ to 1.7 mM, and significantly blunted by nominal absence of extracellular Ca2+, by additional presence of pyrophosphate as well as by presence of p38 inhibitor SB203580. Conclusion: Increasing phosphate concentration stimulates erythrocyte membrane scrambling, an effect depending on extracellular but not intracellular Ca2+ concentration. It is hypothesized that suicidal erythrocyte death is triggered by complexed CaHPO4.

The transport of phosphate between the plasma and dialysate compartments in peritoneal dialysis is influenced by an electric potential difference

DEFF Research Database (Denmark)

Graff, J; Fugleberg, S; Brahm, J

1996-01-01

was not identifiable. Furthermore, it was demonstrated that the electrochemical gradient between plasma water and dialysate favours the diffusive phosphate transport, and both electric and chemical potentials must be taken into account in calculations of the transperitoneal phosphate transport.......Six kinetic models of transperitoneal phosphate transport were formulated and validated on the basis of experimental results obtained from 22 non-diabetic patients undergoing peritoneal dialysis. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective......, and lymphatic convective phosphate transport. Calculations allowed for a 20% protein binding of phosphate. The validation procedure demonstrated that only diffusive and non-lymphatic convective phosphate transport mechanisms were identifiable. A lymphatic convective phosphate transport mechanism...

Study of phosphate release from Bogor botanical gardens’ sediment into pore water using diffusive gradient in thin film (DGT)

Science.gov (United States)

Tirta, A. P.; Saefumillah, A.; Foliatini

2017-04-01

Eutrophication is one of the environmental problems caused by the excessive nutrients in aquatic ecosystems. In most lakes, phosphate is a limiting nutrient for algae photosynthesis. Even though the concentration of phosphate from external loading into the water body has been reduced, eutrophication could still be occured due to internal mobilization of phosphate from the sediment pore water into the overlying water. Therefore, the released phosphate from sediments and their interaction in the pore water must be included in the monitoring of phosphate concentration in aquatic system. The released phosphate from sediment into pore water has been studied by DGT device with ferrihydrite as binding gel and N-N‧-methylenebisacrylamide as crosslinker. The results showed that DGT with 15% acrylamide; 0.1 % N-N‧-methylenebisacrylamide and ferrihydrite as binding gel was suitable for the measurement of the released phosphate from sediment into pore water. The result of the deployed DGT in oxic and anoxic conditions in seven days incubation showed the released phosphate process from the sediment into pore water was affected by incubation time and the existence of oxygen in the environment. The released phosphate from the sediment into pore water in anoxic condition has a higher value than oxic condition. The experimental results of the deployed DGT in natural sediment core at a depth of 1 to 15 cm from the surface of the water for 7 days showed that the sediment has a different phosphate mass profile based on depth. The concentration of phosphate tends to be increased with depth. The maximum CDGT of phosphate released in oxic and anoxic conditions at 7th day period of incubation are 29.23 μg/L at 14 cm depth and 30.19 μg/L at 8 cm depth, respectively.

Biomimetic fabrication of calcium phosphate/chitosan nanohybrid composite in modified simulated body fluids

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K. H. Park

2017-01-01

Full Text Available In this study, nucleation and growth of bone-like hydroxyapatite (HAp mineral in modified simulated body fluids (m-SBF were induced on chitosan (CS substrates, which were prepared by spin coating of chitosan on Ti substrate. The m-SBF showed a two fold increase in the concentrations of calcium and phosphate ions compared to SBF, and the post-NaOH treatment provided stabilization of the coatings. The calcium phosphate/chitosan composite prepared in m-SBF showed homogeneous distribution of approximately 350 nm-sized spherical clusters composed of octacalcium phosphate (OCP; Ca8H2(PO46·5H2O crystalline structure. Chitosan provided a control over the size of calcium phosphate prepared by immersion in m-SBF, and post-NaOH treatment supported the binding of calcium phosphate compound on the Ti surface. Post-NaOH treatment increased hydrophilicity and crystallinity of carbonate apatite, which increased its potential for biomedical application.

Dual and Direction-Selective Mechanisms of Phosphate Transport by the Vesicular Glutamate Transporter

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Julia Preobraschenski

2018-04-01

Full Text Available Summary: Vesicular glutamate transporters (VGLUTs fill synaptic vesicles with glutamate and are thus essential for glutamatergic neurotransmission. However, VGLUTs were originally discovered as members of a transporter subfamily specific for inorganic phosphate (Pi. It is still unclear how VGLUTs accommodate glutamate transport coupled to an electrochemical proton gradient ΔμH+ with inversely directed Pi transport coupled to the Na+ gradient and the membrane potential. Using both functional reconstitution and heterologous expression, we show that VGLUT transports glutamate and Pi using a single substrate binding site but different coupling to cation gradients. When facing the cytoplasm, both ions are transported into synaptic vesicles in a ΔμH+-dependent fashion, with glutamate preferred over Pi. When facing the extracellular space, Pi is transported in a Na+-coupled manner, with glutamate competing for binding but at lower affinity. We conclude that VGLUTs have dual functions in both vesicle transmitter loading and Pi homeostasis within glutamatergic neurons. : Preobraschenski et al. show that the vesicular glutamate transporter functions as a bi-directional phosphate transporter that is coupled with different cations in each direction and hence may play a key role in neuronal phosphate homeostasis. Keywords: VGLUT, SLC17 family, type I Na+-dependent inorganic phosphate transporter, ATPase, proteoliposomes, hybrid vesicles, anti-VGLUT1 nanobody

Phosphorylation and 14-3-3 binding of Arabidopsis trehalose-phosphate synthase 5 in response to 2-deoxyglucose

DEFF Research Database (Denmark)

Harthill, Jean E; Meek, Sarah E M; Morrice, Nick

2006-01-01

Trehalose-6-phosphate is a 'sugar signal' that regulates plant metabolism and development. The Arabidopsis genome encodes trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphatase (TPP) enzymes. It also encodes class II proteins (TPS isoforms 5-11) that contain both TPS-like and TPP...

Stabilization of Cs/Re trapping filters using magnesium phosphate ceramics

International Nuclear Information System (INIS)

Jae Hwan Yang; Jin Myeong Shin; Chang Hwa Lee; Chul Min Heo; Min Ku Jeon; Kweon Ho Kang

2013-01-01

The present study a promising method for stabilizing spent filters trapping cesium and technetium by using magnesium phosphate ceramics. Simulated spent filters were fabricated by vaporizing nonradioactive cesium and rhenium (a surrogate of Tc) through the voloxidizer. In order to reveal the characteristics of spent filters, phase structures and thermal stability were analyzed by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and thermogravimetric analysis techniques. Waste forms were fabricated by crushing spent filters and mixing them with magnesium oxide and potassium phosphate. Characterizations of the waste forms were performed by the analyses of compressive strength, apparent porosity, XRD, and scanning electron microscopy. The waste forms showed the excellent mechanical property compared with that of ordinary Portland cement, with the highest compressive strength of 38.1 MPa in the sample with 30 wt% of Cs-filter. Microstructural analysis suggests that waste materials are encapsulated by the binding matrix composed of magnesium potassium phosphate. The results of characterization suggest that fabricating a sound and durable waste form is possible with magnesium phosphate ceramics. (author)

Recombinant expression of a functional myo-inositol-1-phosphate synthase (MIPS) in Mycobacterium smegmatis.

Science.gov (United States)

Huang, Xinyi; Hernick, Marcy

2015-10-01

Myo-inositol-1-phosphate synthase (MIPS, E.C. 5.5.1.4) catalyzes the first step in inositol production-the conversion of glucose-6-phosphate (Glc-6P) to myo-inositol-1-phosphate. While the three dimensional structure of MIPS from Mycobacterium tuberculosis has been solved, biochemical studies examining the in vitro activity have not been reported to date. Herein we report the in vitro activity of mycobacterial MIPS expressed in E. coli and Mycobacterium smegmatis. Recombinant expression in E. coli yields a soluble protein capable of binding the NAD(+) cofactor; however, it has no significant activity with the Glc-6P substrate. In contrast, recombinant expression in M. smegmatis mc(2)4517 yields a functionally active protein. Examination of structural data suggests that MtMIPS expressed in E. coli adopts a fold that is missing a key helix containing two critical (conserved) Lys side chains, which likely explains the inability of the E. coli expressed protein to bind and turnover the Glc-6P substrate. Recombinant expression in M. smegmatis may yield a protein that adopts a fold in which this key helix is formed enabling proper positioning of important side chains, thereby allowing for Glc-6P substrate binding and turnover. Detailed mechanistic studies may be feasible following optimization of the recombinant MIPS expression protocol in M. smegmatis.

Stabilization of microtubules by inorganic phosphate and its structural analogues, the fluoride complexes of aluminum and beryllium

International Nuclear Information System (INIS)

Carlier, M.F.; Didry, D.; Melki, R.; Chabre, M.; Pantaloni, D.

1988-01-01

In order to elucidate how the elementary reactions of GTP cleavage and subsequent inorganic phosphate (P/sub i/) release, which accompany microtubule assembly, regulate microtubule dynamics, the effect of P/sub i/ and of its structural analogues AlF 4 - and BeF 3 - on the stability of GDP-microtubules has been investigated. Inorganic phosphate binds to microtubules with a low affinity (K/sub D/ = 25 mM) and slows down the rate of GDP-subunit dissociation by about 2 orders of magnitude. AlF 4 - and BeF 3 - exhibit phosphate-like effects with 1000-fold higher affinity. Evidence has been obtained for direct binding of BeF 3 - to microtubules with a stoichiometry of 1 mol of BeF 3 - per mole of GDP-subunit and an equilibrium dissociation constant of 12-15 μM. AlF 4 - and P/sub i/ compete for this site. Phosphate analogues abolish oscillatory polymerization kinetics and slow down microtubule turnover at steady state. In view of these results, the authors propose that P/sub i/ and its structural analogues bind to the site of the γ-phosphate of GTP in the E site and reconstitute a GDP-P/sub i/-microtubule, from which tubulin subunits dissociate very slowly. They therefore understand that, following GTP cleavage on microtubules, P/sub i/ release in the medium is accompanied by a structural change resulting in a large destabilization of the polymer. A cap of slowly dissociating GDP-P/sub i/-subunits prevents depolymerization of the microtubule GDP-core at steady state. The similarity with the actin system is studied

Thermococcus kodakarensis modulates its polar membrane lipids and elemental composition according to growth stage and phosphate availability

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Travis B. Meador

2014-01-01

Full Text Available We observed significant changes in the elemental and intact polar lipid (IPL composition of the archaeon Thermococcus kodakarensis (KOD1 in response to growth stage and phosphorus supply. Reducing the amount of organic supplements and phosphate in growth media resulted in significant decreases in cell size and cellular quotas of carbon (C, nitrogen (N, and phosphorus (P, which coincided with significant increases in cellular IPL quota and IPLs comprising multiple P atoms and hexose moieties. Relatively more cellular P was stored as IPLs in P-limited cells (2-8% compared to control cells (< 0.8%. We also identified a specific IPL biomarker containing a phosphatidyl-N-acetylhexoseamine headgroup that was relatively enriched during rapid cell division. These observations serve as empirical evidence of IPL adaptations in Archaea that will help to interpret the distribution of these biomarkers in natural systems. The reported cell quotas of C, N, and P represent the first such data for a specific archaeon and suggest that thermophiles are C-rich compared to the cell carbon-to-volume relationship reported for planktonic bacteria.

Effect of submarine groundwater discharge containing phosphate on coral calcification

Science.gov (United States)

Yasumoto, J.; Yasumoto, K.; Iijima, M.; Nozaki, M.; Asai, K.; Yasumoto, M. H.

2017-12-01

It is well known that the anthropogenic eutrophication enriched with various substances including phosphate in coastal waters has resulted in coral degradation. However, to the best of our knowledge, the phosphate threshold value to inhibit the coral calcification has been unclear, due to the unknown mechanisms involved in the inhibition of the calcification by phosphate. In island regions, groundwater is one of the most important clues to transport the nutrients contained in livestock or agricultural wastewaters. However, the actual conditions of coastal pollution with such nutrients have not been understood because of unperceived submarine groundwater discharge (SGD). In this study, to quantify of extremely rapid and localized SGD from Ryukyu limestone aquifer, we investigated the rate and concentration of phosphate of SGD using automated seepage mater in Yoron Island, which is located southern part of Japan. And, to elucidate the inhibition mechanisms for phosphate against coral calcification, we examined its effect on the bottom skeleton formation in primary polyps of Acropora digitifera by using the fluorescence derivatizing reagent having phosphate group (FITC-AA). As a result, the SGD was found to contain 1 to 2 µM of phosphate as much as the concentration in the coastal ground water under agricultural land. Moreover, the amount of phosphate contained in the surface layers of bottom calcareous sands close to the region of SGD were about 5 µmol/g. When the primary polyps were treated with 50 µM of FITC-AA, the bottom skeleton of the primary polyps showed the fluorescence from FITC-AA within a few minutes, suggesting the phosphate binding. Furthermore, when the polyps were treated with 10 µM of FITC-AA, irregular patterns of the elongated skeleton were observed. These results led us to conclude that phosphate is transported via a paracellular pathway to the subcalicoblastic extracellular calcifying medium. These results indicate that the phosphate adsorbed

The Effect On the Bones of Condensed Phosphate When Used as Food Additives : Its Importance in Relation to Preventive Medicine

OpenAIRE

Miyako, OMOTO; Tsunehiko, IMAI; Kumiko, SEKI; Ryoji, NOMURA; Yumi, OTAHARA; Department of Environmental and Occupational Health, Toho University, School of Medicine; Department of Environmental and Occupational Health, Toho University, School of Medicine; Department of Environmental and Occupational Health, Toho University, School of Medicine; Department of Environmental and Occupational Health, Toho University, School of Medicine; Department of Environmental and Occupational Health, Toho University, School of Medicine

1997-01-01

Based on the fact that chemical products such as binding agents are produced by mixing three kinds of phosphates with different ratios, we mixed metaphosphate, polyphosphate and pyrophosphate. Each was made to Na-phosphate, K-phosphate, and Ca-phosphate and each was mixed with commercial feeds so that the content of P would be approximately 0.1, 0.15, 0.3, 0.4, 0.6 and 1.0%. The prepared pellets were given to ICR, CF # 1 and AKR strains of mice at 29 days of age for 680 days and observations ...

Interactions of casein micelles with calcium phosphate particles.

Science.gov (United States)

Tercinier, Lucile; Ye, Aiqian; Anema, Skelte G; Singh, Anne; Singh, Harjinder

2014-06-25

Insoluble calcium phosphate particles, such as hydroxyapatite (HA), are often used in calcium-fortified milks as they are considered to be chemically unreactive. However, this study showed that there was an interaction between the casein micelles in milk and HA particles. The caseins in milk were shown to bind to the HA particles, with the relative proportions of bound β-casein, αS-casein, and κ-casein different from the proportions of the individual caseins present in milk. Transmission electron microscopy showed no evidence of intact casein micelles on the surface of the HA particles, which suggested that the casein micelles dissociated either before or during binding. The HA particles behaved as ion chelators, with the ability to bind the ions contained in the milk serum phase. Consequently, the depletion of the serum minerals disrupted the milk mineral equilibrium, resulting in dissociation of the casein micelles in milk.

Bioconversion of lignocellulose-derived sugars to ethanol by engineered Saccharomyces cerevisiae.

Science.gov (United States)

Madhavan, Anjali; Srivastava, Aradhana; Kondo, Akihiko; Bisaria, Virendra S

2012-03-01

Lignocellulosic biomass from agricultural and agro-industrial residues represents one of the most important renewable resources that can be utilized for the biological production of ethanol. The yeast Saccharomyces cerevisiae is widely used for the commercial production of bioethanol from sucrose or starch-derived glucose. While glucose and other hexose sugars like galactose and mannose can be fermented to ethanol by S. cerevisiae, the major pentose sugars D-xylose and L-arabinose remain unutilized. Nevertheless, D-xylulose, the keto isomer of xylose, can be fermented slowly by the yeast and thus, the incorporation of functional routes for the conversion of xylose and arabinose to xylulose or xylulose-5-phosphate in Saccharomyces cerevisiae can help to improve the ethanol productivity and make the fermentation process more cost-effective. Other crucial bottlenecks in pentose fermentation include low activity of the pentose phosphate pathway enzymes and competitive inhibition of xylose and arabinose transport into the cell cytoplasm by glucose and other hexose sugars. Along with a brief introduction of the pretreatment of lignocellulose and detoxification of the hydrolysate, this review provides an updated overview of (a) the key steps involved in the uptake and metabolism of the hexose sugars: glucose, galactose, and mannose, together with the pentose sugars: xylose and arabinose, (b) various factors that play a major role in the efficient fermentation of pentose sugars along with hexose sugars, and (c) the approaches used to overcome the metabolic constraints in the production of bioethanol from lignocellulose-derived sugars by developing recombinant S. cerevisiae strains.

Electronic and Structural Parameters of Phosphorus-Oxygen Bonds in Inorganic Phosphate Crystals

Science.gov (United States)

Atuchin, V. V.; Kesler, V. G.; Pervukhina, N. V.

Wide set of experimental results on binding energy of photoelectrons emitted from P 2p, P 2s, and O 1s core levels has been observed for inorganic phosphate crystals and the parameters were compared using energy differences Δ(O 1s - P 2p) and Δ (O 1s - P 2s) as most robust characteristics. Linear dependence of the binding energy difference on mean chemical bond length L(P-O) between phosphorus and oxygen atoms has been found. The functions are of the forms: Δ (O 1s - P 2p) (eV) = 375.54 + 0.146 · L(P-O) (pm) and Δ (O 1s - P 2s) (eV) = 320.77 + 0.129 · L(P-O) (pm). The dependencies are general for inorganic phosphates and may be used in quantitative component analysis of X-ray photoemission spectra of complex oxide compounds including functional groups with different coordination of P and O atoms.

Mechanism of stimulation of endogenous fermentation in yeast by carbonyl cyanide m-chlorophenylhydrazone

NARCIS (Netherlands)

Noshiro, A.; Purwin, C.; Laux, M.; Nicolaij, K.; Scheffers, W.A.; Holzer, H.

1987-01-01

Addition of the uncoupler and protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) to starved yeast cells starts endogenous alcoholic fermentation lasting about 20 min. Hexose 6-phosphates, fructose 2,6-bisphosphate, and pyruvate accumulate in less than 2 min after addition of CCCP from

A Bacterial Glucanotransferase Can Replace the Complex Maltose Metabolism Required for Starch to Sucrose Conversion in Leaves at Night

DEFF Research Database (Denmark)

Ruzanski, Christian; Smirnova, Julia; Rejzek, Martin

2013-01-01

Controlled conversion of leaf starch to sucrose at night is essential for the normal growth of Arabidopsis. The conversion involves the cytosolic metabolism of maltose to hexose phosphates via an unusual, multidomain protein with 4-glucanotransferase activity, DPE2, believed to transfer glucosyl ...

D-tagatose, a novel hexose: acute effects on carbohydrate tolerance in subjects with and without type 2 diabetes.

Science.gov (United States)

Donner, T W; Wilber, J F; Ostrowski, D

1999-09-01

D-Tagatose (D-tag), a hexose bulk sweetener, does not affect plasma glucose levels when orally administered to rodents. Additionally, D-tag attenuates the rise in plasma glucose after mice are administered oral sucrose. The current study was undertaken to investigate the acute glycaemic effects of oral D-tag alone or in combination with oral glucose in human subjects with and without type 2 diabetes mellitus. Glycaemic responses to D-tag also were investigated in subjects after oral sucrose to examine whether the glucose-lowering effects of D-tag in rodents may result from a direct inhibition of intestinal disaccharidases. Eight normal and eight subjects with diabetes mellitus were administered 75 g of glucose, 75 g of D-tag, or 75 g of D-tag 30 min prior to a 75 g oral glucose tolerance test (OGTT). Five patients with diabetes mellitus were challenged with a 75 g oral sucrose tolerance test (OSTT) with and without oral pre-treatment with 75 g of D-tag. Patients with diabetes mellitus also received separate 0, 10, 15, 20 and 30 g of D-tag 30 min prior to a 75 g OGTT. Oral loading with D-tag alone led to no changes in glucose or insulin levels in either normal patients or those with diabetes mellitus. Pre-OGTT treatment with 75 g D-tag, however, attenuated the rise in glucose levels in patients with diabetes mellitus (p effects seen following larger doses of D-tag support poor absorption of this hexose and suggest that D-tag may act by attenuating glucose absorption in the intestine. D-tag may be a useful therapeutic adjunct in the management of type 2 diabetes mellitus.

Phosphate binding by natural iron-rich colloids in streams

NARCIS (Netherlands)

Baken, S.; Moens, C.; Griffioen, J.J.; Smolders, E.

2016-01-01

Phosphorus (P) in natural waters may be bound to iron (Fe) bearing colloids. However, the natural variation in composition and P binding strength of these colloids remain unclear. We related the composition of "coarse colloids" (colloids in the 0.1-1.2 μm size range) in 47 Belgian streams to the

Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

Energy Technology Data Exchange (ETDEWEB)

Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore)

2012-06-15

Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

Designing calcium phosphate-based bifunctional nanocapsules with bone-targeting properties

International Nuclear Information System (INIS)

Khung, Yit-Lung; Bastari, Kelsen; Cho, Xing Ling; Yee, Wu Aik; Loo, Say Chye Joachim

2012-01-01

Using sodium dodecyl sulphate micelles as template, hollow-cored calcium phosphate nanocapsules were produced. The surfaces of the nanocapsule were subsequently silanised by a polyethylene glycol (PEG)-based silane with an N-hydroxysuccinimide ester end groups which permits for further attachment with bisphosphonates (BP). Characterisations of these nanocapsules were investigated using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy, Fourier Transform Infra-Red Spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Dynamic Light Scattering. To further validate the bone-targeting potential, dentine discs were incubated with these functionalised nanocapsules. FESEM analysis showed that these surface-modified nanocapsules would bind strongly to dentine surfaces compared to non-functionalised nanocapsules. We envisage that respective components would give this construct a bifunctional attribute, whereby (1) the shell of the calcium phosphate nanocapsule would serve as biocompatible coating aiding in gradual osteoconduction, while (2) surface BP moieties, acting as targeting ligands, would provide the bone-targeting potential of these calcium phosphate nanocapsules.

[Modification of retinal photoreceptor membranes and Ca ion binding].

Science.gov (United States)

Korchagin, V P; Berman, A L; Shukoliukov, S A; Rychkova, M P; Etingof, R N

1978-10-01

Calcium binding by modified photoreceptor membranes of cattle retina has been studied. Ca2+-binding the membranes significantly changes after C-phospholipase treatment, displaying the initial growth (less than 65% of lipid phosphorus removed) with subsequent decrease (more than 65% of phosphorus removed). Liposomes of the photoreceptor membranes lipids were found to bind more calcium than do the native photoreceptor membranes. Proteolytic enzymes (papaine, pronase) splitting some rhodopsin fragments do not affect the ability of the membrane to bind Ca2+. The increase of light-induced Ca-binding is observed only after the outer segments preincubation under conditions providing for rhodopsin phosphorylation. This effect was observed also after the splitting of the rhodopsin fragment by papaine. It is concluded that calcium binding in the photoreceptor membranes is mainly due to the phosphate groups of phospholipids.

Dynamics of sugar-metabolic enzymes and sugars accumulation during watermelon (citrullus lanatus) fruit development

International Nuclear Information System (INIS)

Zhang, H.

2016-01-01

We analyzed sugar accumulation and the activities of sugar-metabolic enzymes in ripening fruits of three cultivars of watermelon; a high-sugar type w2, a low-sugar type (w1), and their hybrid. In w2, the glucose and fructose contents were higher than the sucrose content in the earlier stage of fruit development, and fruit growth was accompanied by increases in glucose, fructose, and sucrose contents. The sucrose content increased substantially after 20 days after anthesis (DAA) and it was the main soluble sugar in mature fruit (sucrose: hexoses ratio, 0.71). In W, the fructose and glucose contents were significantly higher than the sucrose content in mature fruit (sucrose: hexoses ratio, 0.25). Comparing the two parent cultivars, sucrose was the most important factor affecting the total sugar content in mature fruit, although glucose and fructose also contributed to total sugar contents. The fructose and glucose contents in the fruit of F1 were mid-way between those of their parents, while the sucrose content was closer to that of W (sucrose:hexoses ratio in F1, 0.26). In the early stage of fruit development of W2, the activities of acid invertase and neutral invertase were higher than those of sucrose synthase and sucrose phosphate synthase. After 20 DAA, the acid invertase and neutral invertase activities decreased and those of sucrose synthase and sucrose phosphate synthase increased, leading to increased sucrose content. In W1, the activities of acid invertase and neutral invertase were higher than those of sucrose synthase and sucrose phosphate synthase at the early stage. The sucrose synthase and sucrose phosphate synthase activities were lower in W1 than in W2 at the later stages of fruit development. The patterns of sugar accumulation and sugar-metabolic enzyme activities during fruit development in F1 were similar to those in W1. (author)

Developing porous carbon with dihydrogen phosphate groups as sulfur host for high performance lithium sulfur batteries

Science.gov (United States)

Cui, Yanhui; Zhang, Qi; Wu, Junwei; Liang, Xiao; Baker, Andrew P.; Qu, Deyang; Zhang, Hui; Zhang, Huayu; Zhang, Xinhe

2018-02-01

Carbon matrix (CM) derived from biomass is low cost and easily mass produced, showing great potential as sulfur host for lithium sulfur batteries. In this paper we report on a dihydrogen phosphate modified CM (PCM-650) prepared from luffa sponge (luffa acutangula) by phosphoric acid treatment. The phosphoric acid not only increases the surface area of the PCM-650, but also introduces dihydrogen phosphate onto PCM-650 (2.28 at% P). Sulfur impregnated (63.6 wt%) PCM-650/S, in comparison with samples with less dihydrogen phosphate LPCM-650/S, shows a significant performance improvement. XPS analysis is conducted for sulfur at different stages, including sulfur (undischarged), polysulfides (discharge to 2.1 V) and short chain sulfides (discharge to 1.7 V). The results consistently show chemical shifts for S2p in PCM-650, suggesting an enhanced adsorption effect. Furthermore, density functional theory (DFT) calculations is used to clarify the molecular binding: carbon/sulfur (0.86 eV), carbon/Li2S (0.3 eV), CH3-O-PO3H2/sulfur (1.24 eV), and CH3-O-PO3H2/Li2S (1.81 eV). It shows that dihydrogen phosphate group can significantly enhance the binding with sulfur and sulfide, consistent with XPS results. Consequently a CM functionalised with dihydrogen phosphate shows great potential as the sulfur host in a Li-S battery.

Structural, kinetic and proteomic characterization of acetyl phosphate-dependent bacterial protein acetylation.

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Misty L Kuhn

Full Text Available The emerging view of Nε-lysine acetylation in eukaryotes is of a relatively abundant post-translational modification (PTM that has a major impact on the function, structure, stability and/or location of thousands of proteins involved in diverse cellular processes. This PTM is typically considered to arise by the donation of the acetyl group from acetyl-coenzyme A (acCoA to the ε-amino group of a lysine residue that is reversibly catalyzed by lysine acetyltransferases and deacetylases. Here, we provide genetic, mass spectrometric, biochemical and structural evidence that Nε-lysine acetylation is an equally abundant and important PTM in bacteria. Applying a recently developed, label-free and global mass spectrometric approach to an isogenic set of mutants, we detected acetylation of thousands of lysine residues on hundreds of Escherichia coli proteins that participate in diverse and often essential cellular processes, including translation, transcription and central metabolism. Many of these acetylations were regulated in an acetyl phosphate (acP-dependent manner, providing compelling evidence for a recently reported mechanism of bacterial Nε-lysine acetylation. These mass spectrometric data, coupled with observations made by crystallography, biochemistry, and additional mass spectrometry showed that this acP-dependent acetylation is both non-enzymatic and specific, with specificity determined by the accessibility, reactivity and three-dimensional microenvironment of the target lysine. Crystallographic evidence shows acP can bind to proteins in active sites and cofactor binding sites, but also potentially anywhere molecules with a phosphate moiety could bind. Finally, we provide evidence that acP-dependent acetylation can impact the function of critical enzymes, including glyceraldehyde-3-phosphate dehydrogenase, triosephosphate isomerase, and RNA polymerase.

Effectiveness and cost-efficiency of phosphate binders in hemodialysis

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Zsifkovits, Johannes

2009-06-01

Full Text Available Health political background: In 2006, the prevalence of chronic renal insufficiency in Germany was 91,718, of which 66,508 patients were on dialysis. The tendency is clearly growing. Scientific background: Chronic renal insufficiency results in a disturbance of the mineral balance. It leads to hyperphosphataemia, which is the strongest independent risk factor for mortality in renal patients. Usually, a reduction in the phosphate intake through nutrition and the amount of phosphate filtered out during dialysis are not sufficient to reduce the serum phosphate values to the recommended value. Therefore, phosphate binders are used to bind ingested phosphate in the digestive tract in order to lower the phosphate concentration in the serum. Four different groups of phosphate binders are available: calcium- and aluminium salts are the traditional therapies. Sevelamer and Lanthanum are recent developments on the market. In varying doses, all phosphate binders are able to effectively lower phosphate concentrations. However, drug therapies have achieved recommended phosphate levels in only 50 percent of patients during the last years. Research questions: How effective and efficient are the different phosphate binders in chronic renal insufficient patients? Methods: The systematic literature search yielded 1,251 abstracts. Following a two-part selection process with predefined criteria 18 publications were included in the assessment. Results: All studies evaluated conclude that serum phosphate, serum calcium and intact parathyroid hormone can be controlled effectively with all phosphate binders. Only the number of episodes of hypercalcaemia is higher when using calcium-containing phosphatebinders compared to Sevelamer and Lanthanum. Regarding the mortality rate, the cardiovascular artery calcification and bone metabolism no definite conclusions can be drawn. In any case, the amount of calcification at study start seems to be crucial for the further

Mevalonate 5-diphosphate mediates ATP binding to the mevalonate diphosphate decarboxylase from the bacterial pathogen Enterococcus faecalis

Energy Technology Data Exchange (ETDEWEB)

Chen, Chun-Liang; Mermoud, James C.; Paul, Lake N.; Steussy, Calvin Nicklaus; Stauffacher, Cynthia V. (Purdue)

2017-10-12

The mevalonate pathway produces isopentenyl diphosphate (IPP), a building block for polyisoprenoid synthesis, and is a crucial pathway for growth of the human bacterial pathogen Enterococcus faecalis. The final enzyme in this pathway, mevalonate diphosphate decarboxylase (MDD), acts on mevalonate diphosphate (MVAPP) to produce IPP while consuming ATP. This essential enzyme has been suggested as a therapeutic target for the treatment of drug-resistant bacterial infections. Here, we report functional and structural studies on the mevalonate diphosphate decarboxylase from E. faecalis (MDDEF). The MDDEF crystal structure in complex with ATP (MDDEF–ATP) revealed that the phosphate-binding loop (amino acids 97–105) is not involved in ATP binding and that the phosphate tail of ATP in this structure is in an outward-facing position pointing away from the active site. This suggested that binding of MDDEF to MVAPP is necessary to guide ATP into a catalytically favorable position. Enzymology experiments show that the MDDEF performs a sequential ordered bi-substrate reaction with MVAPP as the first substrate, consistent with the isothermal titration calorimetry (ITC) experiments. On the basis of ITC results, we propose that this initial prerequisite binding of MVAPP enhances ATP binding. In summary, our findings reveal a substrate-induced substrate-binding event that occurs during the MDDEF-catalyzed reaction. The disengagement of the phosphate-binding loop concomitant with the alternative ATP-binding configuration may provide the structural basis for antimicrobial design against these pathogenic enterococci.

Structure of glycerol-3-phosphate dehydrogenase, an essential monotopic membrane enzyme involved in respiration and metabolism

International Nuclear Information System (INIS)

Yeh, Joanne I.; Chinte, Unmesh; Du, Shoucheng

2008-01-01

Sn-glycerol-3-phosphate dehydrogenase (GlpD) is an essential membrane enzyme, functioning at the central junction of respiration, glycolysis, and phospholipid biosynthesis. Its critical role is indicated by the multitiered regulatory mechanisms that stringently controls its expression and function. Once expressed, GlpD activity is regulated through lipid-enzyme interactions in Escherichia coli. Here, we report seven previously undescribed structures of the fully active E. coli GlpD, up to 1.75 (angstrom) resolution. In addition to elucidating the structure of the native enzyme, we have determined the structures of GlpD complexed with substrate analogues phosphoenolpyruvate, glyceric acid 2-phosphate, glyceraldehyde-3-phosphate, and product, dihydroxyacetone phosphate. These structural results reveal conformational states of the enzyme, delineating the residues involved in substrate binding and catalysis at the glycerol-3-phosphate site. Two probable mechanisms for catalyzing the dehydrogenation of glycerol-3-phosphate are envisioned, based on the conformational states of the complexes. To further correlate catalytic dehydrogenation to respiration, we have additionally determined the structures of GlpD bound with ubiquinone analogues menadione and 2-n-heptyl-4-hydroxyquinoline N-oxide, identifying a hydrophobic plateau that is likely the ubiquinone-binding site. These structures illuminate probable mechanisms of catalysis and suggest how GlpD shuttles electrons into the respiratory pathway. Glycerol metabolism has been implicated in insulin signaling and perturbations in glycerol uptake and catabolism are linked to obesity in humans. Homologs of GlpD are found in practically all organisms, from prokaryotes to humans, with >45% consensus protein sequences, signifying that these structural results on the prokaryotic enzyme may be readily applied to the eukaryotic GlpD enzymes.

Updates to a 13C metabolic flux analysis model for evaluating energy metabolism in cultured cerebellar granule neurons from neonatal rats.

Science.gov (United States)

Jekabsons, Mika B; Gebril, Hoda M; Wang, Yan-Hong; Avula, Bharathi; Khan, Ikhlas A

2017-10-01

A hexose phosphate recycling model previously developed to infer fluxes through the major glucose consuming pathways in cultured cerebellar granule neurons (CGNs) from neonatal rats metabolizing [1,2- 13 C 2 ]glucose was revised by considering reverse flux through the non-oxidative pentose phosphate pathway (PPP) and symmetrical succinate oxidation within the tricarboxylic acid (TCA) cycle. The model adjusts three flux ratios to effect 13 C distribution in the hexose, pentose, and triose phosphate pools, and in TCA cycle malate to minimize the error between predicted and measured 13 C labeling in exported lactate (i.e., unlabeled, single-, double-, and triple-labeled; M, M1, M2, and M3, respectively). Inclusion of reverse non-oxidative PPP flux substantially increased the number of calculations but ultimately had relatively minor effects on the labeling of glycolytic metabolites. From the error-minimized solution in which the predicted M-M3 lactate differed by 0.49% from that measured by liquid chromatography-triple quadrupole mass spectrometry, the neurons exhibited negligible forward non-oxidative PPP flux. Thus, no glucose was used by the pentose cycle despite explicit consideration of hexose phosphate recycling. Mitochondria consumed only 16% of glucose while 45% was exported as lactate by aerobic glycolysis. The remaining 39% of glucose was shunted to pentose phosphates presumably for de novo nucleotide synthesis, but the proportion metabolized through the oxidative PPP vs. the reverse non-oxidative PPP could not be determined. The lactate exported as M1 (2.5%) and M3 (1.2%) was attributed to malic enzyme, which was responsible for 7.8% of pyruvate production (vs. 92.2% by glycolysis). The updated model is more broadly applicable to different cell types by considering bi-directional flux through the non-oxidative PPP. Its application to cultured neurons utilizing glucose as the sole exogenous substrate has demonstrated substantial oxygen-independent glucose

Binding Characteristics of Sphingosine-1-Phosphate to ApoM hints to Assisted Release Mechanism via the ApoM Calyx-Opening

Science.gov (United States)

Zhang, Hansi; Pluhackova, Kristyna; Jiang, Zhenyan; Böckmann, Rainer A.

2016-08-01

Sphingosine-1-phosphate (S1P) is a lysophospholipid mediator carried by the HDL-associated apoM protein in blood, regulating many physiological processes by activating the G protein-coupled S1P receptor in mammals. Despite the solved crystal structure of the apoM-S1P complex, the mechanism of S1P release from apoM as a part of the S1P pathway is unknown. Here, the dynamics of the wild type apoM-S1P complex as well as of mutants were investigated by means of atomistic molecular dynamics simulations. The potential of mean force for S1P unbinding from apoM reflected a large binding strength of more than 60 kJ/mol. This high unbinding free energy for S1P underlines the observed specificity of the physiological effects of S1P as it suggests that the spontaneous release of S1P from apoM is unlikely. Instead, S1P release and thus the control of this bioactive lipid probably requires the tight interaction with other molecules, e.g. with the S1P receptor. Mutations of specific S1P anchoring residues of apoM decreased the energetic barrier by up to 20 kJ/mol. Moreover, the ligand-free apoM protein is shown to adopt a more open upper hydrophilic binding pocket and to result in complete closure of the lower hydrophobic cavity, suggesting a mechanism for adjusting the gate for ligand access.

Identification of Glyceraldehyde-3-phosphate dehydrogenase (GAPDH as a binding protein for a 68-kDa Bacillus thuringiensis parasporal protein cytotoxic against leukaemic cells

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Nadarajah Vishna

2010-11-01

Full Text Available Abstract Background Bacillus thuringiensis (Bt, an ubiquitous gram-positive spore-forming bacterium forms parasporal proteins during the stationary phase of its growth. Recent findings of selective human cancer cell-killing activity in non-insecticidal Bt isolates resulted in a new category of Bt parasporal protein called parasporin. However, little is known about the receptor molecules that bind parasporins and the mechanism of anti-cancer activity. A Malaysian Bt isolate, designated Bt18 produces parasporal protein that exhibit preferential cytotoxic activity for human leukaemic T cells (CEM-SS but is non-cytotoxic to normal T cells or other cancer cell lines such as human cervical cancer (HeLa, human breast cancer (MCF-7 and colon cancer (HT-29 suggesting properties similar to parasporin. In this study we aim to identify the binding protein for Bt18 in human leukaemic T cells. Methods Bt18 parasporal protein was separated using Mono Q anion exchange column attached to a HPLC system and antibody was raised against the purified 68-kDa parasporal protein. Receptor binding assay was used to detect the binding protein for Bt18 parasporal protein in CEM-SS cells and the identified protein was sent for N-terminal sequencing. NCBI protein BLAST was used to analyse the protein sequence. Double immunofluorescence staining techniques was applied to localise Bt18 and binding protein on CEM-SS cell. Results Anion exchange separation of Bt18 parasporal protein yielded a 68-kDa parasporal protein with specific cytotoxic activity. Polyclonal IgG (anti-Bt18 for the 68-kDa parasporal protein was successfully raised and purified. Receptor binding assay showed that Bt18 parasporal protein bound to a 36-kDa protein from the CEM-SS cells lysate. N-terminal amino acid sequence of the 36-kDa protein was GKVKVGVNGFGRIGG. NCBI protein BLAST revealed that the binding protein was Glyceraldehyde-3-phosphate dehydrogenase (GAPDH. Double immunofluorescence staining showed

Analysis of RNA binding by the dengue virus NS5 RNA capping enzyme.

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Brittney R Henderson

Full Text Available Flaviviruses are small, capped positive sense RNA viruses that replicate in the cytoplasm of infected cells. Dengue virus and other related flaviviruses have evolved RNA capping enzymes to form the viral RNA cap structure that protects the viral genome and directs efficient viral polyprotein translation. The N-terminal domain of NS5 possesses the methyltransferase and guanylyltransferase activities necessary for forming mature RNA cap structures. The mechanism for flavivirus guanylyltransferase activity is currently unknown, and how the capping enzyme binds its diphosphorylated RNA substrate is important for deciphering how the flavivirus guanylyltransferase functions. In this report we examine how flavivirus NS5 N-terminal capping enzymes bind to the 5' end of the viral RNA using a fluorescence polarization-based RNA binding assay. We observed that the K(D for RNA binding is approximately 200 nM Dengue, Yellow Fever, and West Nile virus capping enzymes. Removal of one or both of the 5' phosphates reduces binding affinity, indicating that the terminal phosphates contribute significantly to binding. RNA binding affinity is negatively affected by the presence of GTP or ATP and positively affected by S-adensyl methoninine (SAM. Structural superpositioning of the dengue virus capping enzyme with the Vaccinia virus VP39 protein bound to RNA suggests how the flavivirus capping enzyme may bind RNA, and mutagenesis analysis of residues in the putative RNA binding site demonstrate that several basic residues are critical for RNA binding. Several mutants show differential binding to 5' di-, mono-, and un-phosphorylated RNAs. The mode of RNA binding appears similar to that found with other methyltransferase enzymes, and a discussion of diphosphorylated RNA binding is presented.

Computational Design of Biomimetic Phosphate Scavengers

DEFF Research Database (Denmark)

Gruber, Mathias Felix; Wood, Elizabeth Baker; Truelsen, Sigurd Friis

2015-01-01

Phosphorus has long been the target of much research, but in recent years the focus has shifted from being limited only to reducing its detrimental environmental impact, to also looking at how it is linked to the global food security. Therefore, the interest in finding novel techniques for phosph......Phosphorus has long been the target of much research, but in recent years the focus has shifted from being limited only to reducing its detrimental environmental impact, to also looking at how it is linked to the global food security. Therefore, the interest in finding novel techniques...... for phosphorus recovery, as well as improving existing techniques, has increased. In this study we apply a hybrid simulation approach of molecular dynamics and quantum mechanics to investigate the binding modes of phosphate anions by a small intrinsically disordered peptide. Our results confirm...... phosphate could be the starting point of new novel technological approaches toward phosphorus recovery, and they represent an excellent model system for investigating the nature and dynamics of functional de novo designed intrinsically disordered proteins....

Phosphate and arsenate removal efficiency by thermostable ferritin enzyme from Pyrococcus furiosus using radioisotopes

KAUST Repository

Sevcenco, Ana-Maria

2015-03-13

Oxo-anion binding properties of the thermostable enzyme ferritin from Pyrococcus furiosus were characterized with radiography. Radioisotopes 32P and 76As present as oxoanions were used to measure the extent and the rate of their absorption by the ferritin. Thermostable ferritin proved to be an excellent system for rapid phosphate and arsenate removal from aqueous solutions down to residual concentrations at the picomolar level. These very low concentrations make thermostable ferritin a potential tool to considerably mitigate industrial biofouling by phosphate limitation or to remove arsenate from drinking water.

Turn-on fluorescent sensor for Zinc and Cadmium ions based on quinolone and its sequential response to phosphate

International Nuclear Information System (INIS)

Liu, Xiaoyan; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xue, Kun; Xu, Kuoxi

2017-01-01

Sequential fluorescence sensing of Zn 2+ /Cd 2+ ions and phosphate anion by new quinoline based sensors(L1 and L2) have been presented. Sensors exhibit highly selective fluorescence “turn-on” sensing properties to Zn 2+ /Cd 2+ ions in CH 3 OH/H 2 O(1/1, v/v, Tris, 10 mol·L −1 , pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H 2 PO 4 - and HPO 4 2- anions through fluorescence “turn-off” respond. The results of Zn 2+ /Cd 2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn 2+ / Cd 2+ ions and phosphate anion detection in aqueous media. - Graphical abstract: Sequential fluorescence sensing of Zn 2+ /Cd 2+ ions and phosphate anion by new quinoline based sensors (L1 and L2) have been presented. Sensors exhibit highly selective and sensitive fluorescence “turn-on” sensing properties to Zn 2+ /Cd 2+ ions in CH 3 OH/H 2 O(1/1, v/v, Tris, 10 mM, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H 2 PO 4 - and HPO 4 2- anions through fluorescence “turn-off” respond. Zn 2+ /Cd 2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn 2+ / Cd 2+ ions and phosphate anion detection in aqueous media.

It takes two to tango: defining an essential second active site in pyridoxal 5'-phosphate synthase.

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Cyril Moccand

Full Text Available The prevalent de novo biosynthetic pathway of vitamin B6 involves only two enzymes (Pdx1 and Pdx2 that form an ornate multisubunit complex functioning as a glutamine amidotransferase. The synthase subunit, Pdx1, utilizes ribose 5-phosphate and glyceraldehyde 3-phosphate, as well as ammonia derived from the glutaminase activity of Pdx2 to directly form the cofactor vitamer, pyridoxal 5'-phosphate. Given the fact that a single enzyme performs the majority of the chemistry behind this reaction, a complicated mechanism is anticipated. Recently, the individual steps along the reaction co-ordinate are beginning to be unraveled. In particular, the binding of the pentose substrate and the first steps of the reaction have been elucidated but it is not known if the latter part of the chemistry, involving the triose sugar, takes place in the same or a disparate site. Here, we demonstrate through the use of enzyme assays, enzyme kinetics, and mutagenesis studies that indeed a second site is involved in binding the triose sugar and moreover, is the location of the final vitamin product, pyridoxal 5'-phosphate. Furthermore, we show that product release is triggered by the presence of a PLP-dependent enzyme. Finally, we provide evidence that a single arginine residue of the C terminus of Pdx1 is responsible for coordinating co-operativity in this elaborate protein machinery.

Bioactivity tests of calcium phosphates with variant molar ratios of main components.

Science.gov (United States)

Pluta, Klaudia; Sobczak-Kupiec, Agnieszka; Półtorak, Olga; Malina, Dagmara; Tyliszczak, Bożena

2018-03-09

Calcium phosphates constitute attractive materials of biomedical applications. Among them particular attention is devoted to bioactive hydroxyapatite (HAp) and bioresorbable tricalcium phosphate (TCP) that possess ability to bind to living bones and can be used clinically as important bone substitutes. Notably, in vivo bone bioactivity can be predicted from apatite formation of bone immersed in SBF fluids. Thus, analyses of behavior of calcium phosphates immersed in various bio fluids are of great importance. Recently, stoichiometric HAp and TCP structures have been widely studied, whereas only limited number of publications have been devoted to analyses of nonstoichiometric calcium phosphates. Here, we report physicochemical analysis of natural and synthetic phosphates with variable Ca/P molar ratios. Subsequently attained structures were subjected to incubation in either artificial saliva or Ringer's fluids. Both pH and conductivity of such fluids were determined before and after incubation. Furthermore, the influence of the Ca/P values on such parameters was exemplified. Physicochemical analysis of received materials was performed by XRD and FT-IR characterization techniques. Their potential antibacterial activity and behavior in the presence of infectious microorganisms as Escherichia coli and Staphylococcus aureus was also evaluated. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2018. © 2018 Wiley Periodicals, Inc.

Metabolism of Mannose in Cultured Primary Rat Neurons.

Science.gov (United States)

Rastedt, Wiebke; Blumrich, Eva-Maria; Dringen, Ralf

2017-08-01

Glucose is the main peripheral substrate for energy production in the brain. However, as other hexoses are present in blood and cerebrospinal fluid, we have investigated whether neurons have the potential to metabolize, in addition to glucose, also the hexoses mannose, fructose or galactose. Incubation of primary cerebellar granule neurons in the absence of glucose caused severe cell toxicity within 24 h, which could not be prevented by application of galactose or fructose, while the cells remained viable during incubation in the presence of either mannose or glucose. In addition, cultured neurons produced substantial and almost identical amounts of lactate after exposure to either glucose or mannose, while lactate production was low in the presence of fructose and hardly detectable during incubations without hexoses or with galactose as carbon source. Determination of the K M values of hexokinase in lysates of cultured neurons for the hexoses revealed values in the micromolar range for mannose (32 ± 2 µM) and glucose (59 ± 10 µM) and in the millimolar range for fructose (4.4 ± 2.3 mM), demonstrating that mannose is efficiently phosphorylated by neuronal hexokinase. Finally, cultured neurons contained reasonable specific activity of the enzyme phosphomannose isomerase, which is required for isomerization of the hexokinase product mannose-6-phosphate into the glycolysis intermediate fructose-6-phosphate. These data demonstrate that cultured cerebellar granule neurons have the potential and express the required enzymes to efficiently metabolize mannose, while galactose and fructose serve at best poorly as extracellular carbon sources for neurons.

Structural Diversity Within the Mononuclear and Binuclear Active Sites of N-Acetyl-D-Glucosamine-6-Phosphate Deacetylase

Energy Technology Data Exchange (ETDEWEB)

Hall,R.; Brown, S.; Fedorov, A.; Fedorov, E.; Xu, C.; Babbitt, P.; Almo, S.; Raushel, F.

2007-01-01

NagA catalyzes the hydrolysis of N-acetyl-D-glucosamine-6-phosphate to D-glucosamine-6-phosphate and acetate. X-ray crystal structures of NagA from Escherichia coli were determined to establish the number and ligation scheme for the binding of zinc to the active site and to elucidate the molecular interactions between the protein and substrate. The three-dimensional structures of the apo-NagA, Zn-NagA, and the D273N mutant enzyme in the presence of a tight-binding N-methylhydroxyphosphinyl-D-glucosamine-6-phosphate inhibitor were determined. The structure of the Zn-NagA confirms that this enzyme binds a single divalent cation at the beta-position in the active site via ligation to Glu-131, His-195, and His-216. A water molecule completes the ligation shell, which is also in position to be hydrogen bonded to Asp-273. In the structure of NagA bound to the tight binding inhibitor that mimics the tetrahedral intermediate, the methyl phosphonate moiety has displaced the hydrolytic water molecule and is directly coordinated to the zinc within the active site. The side chain of Asp-273 is positioned to activate the hydrolytic water molecule via general base catalysis and to deliver this proton to the amino group upon cleavage of the amide bond of the substrate. His-143 is positioned to help polarize the carbonyl group of the substrate in conjunction with Lewis acid catalysis by the bound zinc. The inhibitor is bound in the {alpha}-configuration at the anomeric carbon through a hydrogen bonding interaction of the hydroxyl group at C-1 with the side chain of His-251. The phosphate group of the inhibitor attached to the hydroxyl at C-6 is ion paired with Arg-227 from the adjacent subunit. NagA from Thermotoga maritima was shown to require a single divalent cation for full catalytic activity.

Structural and Functional Insight of Sphingosine 1-Phosphate-Mediated Pathogenic Metabolic Reprogramming in Sickle Cell Disease.

Science.gov (United States)

Sun, Kaiqi; D'Alessandro, Angelo; Ahmed, Mostafa H; Zhang, Yujin; Song, Anren; Ko, Tzu-Ping; Nemkov, Travis; Reisz, Julie A; Wu, Hongyu; Adebiyi, Morayo; Peng, Zhangzhe; Gong, Jing; Liu, Hong; Huang, Aji; Wen, Yuan Edward; Wen, Alexander Q; Berka, Vladimir; Bogdanov, Mikhail V; Abdulmalik, Osheiza; Han, Leng; Tsai, Ah-Lim; Idowu, Modupe; Juneja, Harinder S; Kellems, Rodney E; Dowhan, William; Hansen, Kirk C; Safo, Martin K; Xia, Yang

2017-11-10

Elevated sphingosine 1-phosphate (S1P) is detrimental in Sickle Cell Disease (SCD), but the mechanistic basis remains obscure. Here, we report that increased erythrocyte S1P binds to deoxygenated sickle Hb (deoxyHbS), facilitates deoxyHbS anchoring to the membrane, induces release of membrane-bound glycolytic enzymes and in turn switches glucose flux towards glycolysis relative to the pentose phosphate pathway (PPP). Suppressed PPP causes compromised glutathione homeostasis and increased oxidative stress, while enhanced glycolysis induces production of 2,3-bisphosphoglycerate (2,3-BPG) and thus increases deoxyHbS polymerization, sickling, hemolysis and disease progression. Functional studies revealed that S1P and 2,3-BPG work synergistically to decrease both HbA and HbS oxygen binding affinity. The crystal structure at 1.9 Å resolution deciphered that S1P binds to the surface of 2,3-BPG-deoxyHbA and causes additional conformation changes to the T-state Hb. Phosphate moiety of the surface bound S1P engages in a highly positive region close to α1-heme while its aliphatic chain snakes along a shallow cavity making hydrophobic interactions in the "switch region", as well as with α2-heme like a molecular "sticky tape" with the last 3-4 carbon atoms sticking out into bulk solvent. Altogether, our findings provide functional and structural bases underlying S1P-mediated pathogenic metabolic reprogramming in SCD and novel therapeutic avenues.

The Stringent Response Induced by Phosphate Limitation Promotes Purine Salvage in Agrobacterium fabrum.

Science.gov (United States)

Sivapragasam, Smitha; Deochand, Dinesh K; Meariman, Jacob K; Grove, Anne

2017-10-31

Agrobacterium fabrum induces tumor growth in susceptible plant species. The upregulation of virulence genes that occurs when the bacterium senses plant-derived compounds is enhanced by acidic pH and limiting inorganic phosphate. Nutrient starvation may also trigger the stringent response, and purine salvage is among the pathways expected to be favored under such conditions. We show here that phosphate limitation induces the stringent response, as evidenced by production of (p)ppGpp, and that the xdhCSML operon encoding the purine salvage enzyme xanthine dehydrogenase is upregulated ∼15-fold. The xdhCSML operon is under control of the TetR family transcription factor XdhR; direct binding of ppGpp to XdhR attenuates DNA binding, and the enhanced xdhCSML expression correlates with increased cellular levels of (p)ppGpp. Xanthine dehydrogenase may also divert purines away from salvage pathways to form urate, the ligand for the transcription factor PecS, which in the plant pathogen Dickeya dadantii is a key regulator of virulence gene expression. However, urate levels remain low under conditions that produce increased levels of xdhCSML expression, and neither acidic pH nor limiting phosphate results in induction of genes under control of PecS. Instead, expression of such genes is induced only by externally supplemented urate. Taken together, our data indicate that purine salvage is favored during the stringent response induced by phosphate starvation, suggesting that control of this pathway may constitute a novel approach to modulating virulence. Because bacterial purine catabolism appears to be unaffected, as evidenced by the absence of urate accumulation, we further propose that the PecS regulon is induced by only host-derived urate.

Agonist-dependent effects of mutations in the sphingosine-1-phosphate type 1 receptor

NARCIS (Netherlands)

van Loenen, Pieter B.; de Graaf, Chris; Verzijl, Dennis; Leurs, Rob; Rognan, Didier; Peters, Stephan L. M.; Alewijnse, Astrid E.

2011-01-01

The sphingosine-1-phosphate type 1 (S1P(1)) receptor is a new target in the treatment of auto-immune diseases as evidenced by the recent approval of FTY720 (Fingolimod). The ligand-binding pocket of the S1P(1) receptor has been generally characterised but detailed insight into ligand-specific

Zinc-phosphate nanoparticles with reversibly attached TNF-α analogs: an interesting concept for potential use in active immunotherapy

International Nuclear Information System (INIS)

Hribar, Gorazd; Žnidaršič, Andrej; Bele, Marjan; Maver, Uroš; Caserman, Simon; Gaberšček, Miran; Gaberc-Porekar, Vladka

2011-01-01

The authors’ intention was to prepare nanometer-sized zinc-phosphate nanoparticles that would be capable of binding histidine-rich TNF-α analogs onto their surface via a coordinative bond. Zinc-phosphate nanoparticles with a size of around 60 nm were prepared by a wet precipitation method and characterized using SEM, EDX, XRD, and DLS. First, BSA was bound as a testing protein, afterward two TNF-α analogs with decreased activity were bound to the described nanoparticles. The efficiency of binding and the existence of coordinative bond were confirmed with SDS-PAGE analysis. During binding, particle storage, and release experiments, the prepared TNF-α analogs retained their biological activity—hence the epitopes necessary for formation of antibodies stayed intact. The particle size did not change within a period of 2 weeks. No significant agglomeration was observed, the particles could be quickly dispersed in ultrasound. The present nanoparticles and the general approach of coordinative binding are widely applicable for natural and engineered histidine-rich proteins. The nanoparticles bearing appropriate TNF-α analogs could also be potentially used for active immunotherapy to tackle the chronic inflammatory diseases associated with pathogenically elevated levels of TNF-α.

Triiodothyronine (T3)-associated upregulation and downregulation of nuclear T3 binding in the human fibroblast cell (MRC-5)--stimulation of malic enzyme, glucose-6-phosphate-dehydrogenase, and 6-phosphogluconate-dehydrogenase by insulin, but not by T3

DEFF Research Database (Denmark)

Matzen, L E; Kristensen, S R; Kvetny, J

1991-01-01

The specific nuclear binding of triiodothyronine (T3) (NBT3) and the activity of malic enzyme (ME), glucose-6-phosphate-dehydrogenase (G6PD), and 6-phosphogluconate-dehydrogenase (6PGD) were studied in the human fibroblast cell (MRC-5). The overall apparent binding affinity (Ka) was 2.7 x 10(9) L.......mol-1 estimated from kinetic studies of nuclear T3 binding, and 2.5 x 10(9) L.mol-1 estimated from equilibrium studies. The scatchard plots were curvilinear and composed of a high-affinity binding site with Ka1 3.4 +/- 0.7 x 10(9) L.mol-1 and maximal binding capacity (MBC) MBC1 57.0 +/- 11.9 fmol/mg DNA...... and a low-affinity binding site with Ka2 2.9 +/- 1.1 x 10(8) L.mol-1 and MBC2 124.7 +/- 22.1 fmol/mg DNA (n = 6). Incubation of cells with 6 nmol/L T3 for 20 hours reduced NBT3 to 62.2% +/- 15.7% (P less than .01, n = 11). The Ka estimated from kinetic studies was reduced to 6.7 x 10(7) L.mol-1...

Role of hexose transport in control of glycolytic flux in Saccharomyces cerevisiae.

Science.gov (United States)

Elbing, Karin; Larsson, Christer; Bill, Roslyn M; Albers, Eva; Snoep, Jacky L; Boles, Eckhard; Hohmann, Stefan; Gustafsson, Lena

2004-09-01

The yeast Saccharomyces cerevisiae predominantly ferments glucose to ethanol at high external glucose concentrations, irrespective of the presence of oxygen. In contrast, at low external glucose concentrations and in the presence of oxygen, as in a glucose-limited chemostat, no ethanol is produced. The importance of the external glucose concentration suggests a central role for the affinity and maximal transport rates of yeast's glucose transporters in the control of ethanol production. Here we present a series of strains producing functional chimeras between the hexose transporters Hxt1 and Hxt7, each of which has distinct glucose transport characteristics. The strains display a range of decreasing glycolytic rates resulting in a proportional decrease in ethanol production. Using these strains, we show for the first time that at high glucose levels, the glucose uptake capacity of wild-type S. cerevisiae does not control glycolytic flux during exponential batch growth. In contrast, our chimeric Hxt transporters control the rate of glycolysis to a high degree. Strains whose glucose uptake is mediated by these chimeric transporters will undoubtedly provide a powerful tool with which to examine in detail the mechanism underlying the switch between fermentation and respiration in S. cerevisiae and will provide new tools for the control of industrial fermentations.

Involvement of glucocorticoid prereceptor metabolism and signaling in rat visceral adipose tissue lipid metabolism after chronic stress combined with high-fructose diet.

Science.gov (United States)

Bursać, Biljana; Djordjevic, Ana; Veličković, Nataša; Milutinović, Danijela Vojnović; Petrović, Snježana; Teofilović, Ana; Gligorovska, Ljupka; Preitner, Frederic; Tappy, Luc; Matić, Gordana

2018-05-03

Both fructose overconsumption and increased glucocorticoids secondary to chronic stress may contribute to overall dyslipidemia. In this study we specifically assessed the effects and interactions of dietary fructose and chronic stress on lipid metabolism in the visceral adipose tissue (VAT) of male Wistar rats. We analyzed the effects of 9-week 20% high fructose diet and 4-week chronic unpredictable stress, separately and in combination, on VAT histology, glucocorticoid prereceptor metabolism, glucocorticoid receptor subcellular redistribution and expression of major metabolic genes. Blood triglycerides and fatty acid composition were also measured to assess hepatic Δ9 desaturase activity. The results showed that fructose diet increased blood triglycerides and Δ9 desaturase activity. On the other hand, stress led to corticosterone elevation, glucocorticoid receptor activation and decrease in adipocyte size, while phosphoenolpyruvate carboxykinase, adipose tissue triglyceride lipase, FAT/CD36 and sterol regulatory element binding protein-1c (SREBP-1c) were increased, pointing to VAT lipolysis and glyceroneogenesis. The combination of stress and fructose diet was associated with marked stimulation of fatty acid synthase and acetyl-CoA carboxylase mRNA level and with increased 11β-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase protein levels, suggesting a coordinated increase in hexose monophosphate shunt and de novo lipogenesis. It however did not influence the level of peroxisome proliferator-activated receptor-gamma, SREBP-1c and carbohydrate responsive element-binding protein. In conclusion, our results showed that only combination of dietary fructose and stress increase glucocorticoid prereceptor metabolism and stimulates lipogenic enzyme expression suggesting that interaction between stress and fructose may be instrumental in promoting VAT expansion and dysfunction. Copyright © 2018 Elsevier B.V. All rights reserved.

The Production and Utilization of GDP-glucose in the Biosynthesis of Trehalose 6-Phosphate by Streptomyces venezuelae.

Science.gov (United States)

Asención Diez, Matías D; Miah, Farzana; Stevenson, Clare E M; Lawson, David M; Iglesias, Alberto A; Bornemann, Stephen

2017-01-20

Trehalose-6-phosphate synthase OtsA from streptomycetes is unusual in that it uses GDP-glucose as the donor substrate rather than the more commonly used UDP-glucose. We now confirm that OtsA from Streptomyces venezuelae has such a preference for GDP-glucose and can utilize ADP-glucose to some extent too. A crystal structure of the enzyme shows that it shares twin Rossmann-like domains with the UDP-glucose-specific OtsA from Escherichia coli However, it is structurally more similar to Streptomyces hygroscopicus VldE, a GDP-valienol-dependent pseudoglycosyltransferase enzyme. Comparison of the donor binding sites reveals that the amino acids associated with the binding of diphosphoribose are almost all identical in these three enzymes. By contrast, the amino acids associated with binding guanine in VldE (Asn, Thr, and Val) are similar in S. venezuelae OtsA (Asp, Ser, and Phe, respectively) but not conserved in E. coli OtsA (His, Leu, and Asp, respectively), providing a rationale for the purine base specificity of S. venezuelae OtsA. To establish which donor is used in vivo, we generated an otsA null mutant in S. venezuelae The mutant had a cell density-dependent growth phenotype and accumulated galactose 1-phosphate, glucose 1-phosphate, and GDP-glucose when grown on galactose. To determine how the GDP-glucose is generated, we characterized three candidate GDP-glucose pyrophosphorylases. SVEN_3027 is a UDP-glucose pyrophosphorylase, SVEN_3972 is an unusual ITP-mannose pyrophosphorylase, and SVEN_2781 is a pyrophosphorylase that is capable of generating GDP-glucose as well as GDP-mannose. We have therefore established how S. venezuelae can make and utilize GDP-glucose in the biosynthesis of trehalose 6-phosphate. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The Production and Utilization of GDP-glucose in the Biosynthesis of Trehalose 6-Phosphate by Streptomyces venezuelae*

Science.gov (United States)

Asención Diez, Matías D.; Miah, Farzana; Stevenson, Clare E. M.; Lawson, David M.; Iglesias, Alberto A.; Bornemann, Stephen

2017-01-01

Trehalose-6-phosphate synthase OtsA from streptomycetes is unusual in that it uses GDP-glucose as the donor substrate rather than the more commonly used UDP-glucose. We now confirm that OtsA from Streptomyces venezuelae has such a preference for GDP-glucose and can utilize ADP-glucose to some extent too. A crystal structure of the enzyme shows that it shares twin Rossmann-like domains with the UDP-glucose-specific OtsA from Escherichia coli. However, it is structurally more similar to Streptomyces hygroscopicus VldE, a GDP-valienol-dependent pseudoglycosyltransferase enzyme. Comparison of the donor binding sites reveals that the amino acids associated with the binding of diphosphoribose are almost all identical in these three enzymes. By contrast, the amino acids associated with binding guanine in VldE (Asn, Thr, and Val) are similar in S. venezuelae OtsA (Asp, Ser, and Phe, respectively) but not conserved in E. coli OtsA (His, Leu, and Asp, respectively), providing a rationale for the purine base specificity of S. venezuelae OtsA. To establish which donor is used in vivo, we generated an otsA null mutant in S. venezuelae. The mutant had a cell density-dependent growth phenotype and accumulated galactose 1-phosphate, glucose 1-phosphate, and GDP-glucose when grown on galactose. To determine how the GDP-glucose is generated, we characterized three candidate GDP-glucose pyrophosphorylases. SVEN_3027 is a UDP-glucose pyrophosphorylase, SVEN_3972 is an unusual ITP-mannose pyrophosphorylase, and SVEN_2781 is a pyrophosphorylase that is capable of generating GDP-glucose as well as GDP-mannose. We have therefore established how S. venezuelae can make and utilize GDP-glucose in the biosynthesis of trehalose 6-phosphate. PMID:27903647

Positively-charged semi-tunnel is a structural and surface characteristic of polyphosphate-binding proteins: an in-silico study.

Directory of Open Access Journals (Sweden)

Zheng Zachory Wei

Full Text Available Phosphate is essential for all major life processes, especially energy metabolism and signal transduction. A linear phosphate polymer, polyphosphate (polyP, linked by high-energy phosphoanhydride bonds, can interact with various proteins, playing important roles as an energy source and regulatory factor. However, polyP-binding structures are largely unknown. Here we proposed a putative polyP binding site, a positively-charged semi-tunnel (PCST, identified by surface electrostatics analyses in polyP kinases (PPKs and many other polyP-related proteins. We found that the PCSTs in varied proteins were folded in different secondary structure compositions. Molecular docking calculations revealed a significant value for binding affinity to polyP in PCST-containing proteins. Utilizing the PCST identified in the β subunit of PPK3, we predicted the potential polyP-binding domain of PPK3. The discovery of this feature facilitates future searches for polyP-binding proteins and discovery of the mechanisms for polyP-binding activities. This should greatly enhance the understanding of the many physiological functions of protein-bound polyP and the involvement of polyP and polyP-binding proteins in various human diseases.

A phosphate starvation-driven bidirectional promoter as a potential tool for crop improvement and in vitro plant biotechnology.

Science.gov (United States)

Araceli, Oropeza-Aburto; Alfredo, Cruz-Ramírez; Javier, Mora-Macías; Luis, Herrera-Estrella

2017-05-01

Phosphate (Pi)-deficient soils are a major limitant factor for crop production in many regions of the world. Despite that plants have innovated several developmental and biochemical strategies to deal with this stress, there are still massive extensions of land which combine several abiotic stresses, including phosphate starvation, that limit their use for plant growth and food production. In several plant species, a genetic programme underlies the biochemical and developmental responses of the organism to cope with low phosphate (Pi) availability. Both protein- and miRNA-coding genes involved in the adaptative response are transcriptionally activated upon Pi starvation. Several of the responsive genes have been identified as transcriptional targets of PHR1, a transcription factor that binds a conserved cis-element called PHR1-binding site (P1BS). Our group has previously described and characterized a minimal genetic arrangement that includes two P1BS elements, as a phosphate-responsive enhancer (EZ2). Here, we report the engineering and successful use of a phosphate-dependent bidirectional promoter, which has been designed and constructed based on the palindromic sequences of the two P1BS elements present in EZ2. This bidirectional promoter has a potential use in both plant in vitro approaches and in the generation of improved crops adapted to Pi starvation and other abiotic stresses. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Additional synthesis of starch from sucrose in leaves of arabidopsis in the light

International Nuclear Information System (INIS)

Keerberg, O.; Ivanova, H.; Keerberg, H.; Paernik, T.

2005-01-01

Full text: Accumulating during daytime starch is converted in the night into sucrose and consumed in respiratory, biosynthetic and transport processes. However in the light the degradation and conversion of starch are blocked. In pulse chase experiments with wild type plants and starchless mutants pgm or adg1 of arabidopsis an increase of starch radioactivity during chase in nonradioactive medium in the light was detected. These findings suggest that starch was additionally synthesized from labeled cytosolic soluble photosynthates, preferentially from sucrose. Radiogasometric studies of gas exchange have revealed that sucrose is consumed also in photorespiratory decarboxylations. To be involved in photorespiration the products of sucrose degradation must be transported from cytosol into chloroplast. We presume that derived from sucrose hexoses are transported into chloroplast by hexose transporter and phosphorylated there in hexokinase reaction. The phosphorylated hexoses may be consumed either for additional synthesis of starch or incorporated into the reductive pentose phosphate cycle and, via this cycle, into the glycolate cycle. (author)

Oxygen binding properties of hemoglobin from the white rhinoceros (beta 2-GLU) and the tapir.

Science.gov (United States)

Baumann, R; Mazur, G; Braunitzer, G

1984-04-01

The beta-chain of rhinoceros hemoglobin contains glutamic acid at position beta 2, and important site for the binding of organic phosphates. We have investigated the oxygen binding properties of this hemoglobin and its interaction with ATP, 2,3-diphosphoglycerate, CO2 and chloride. The results show that the presence of GLU at position beta 2 nearly abolishes the effect of organic phosphates and CO2, whereas the oxygen-linked binding of chloride is not affected. Thus rhinoceros hemoglobin has only protons and chloride anions as major allosteric effectors for the control of its oxygen affinity. From the results obtained with hemoglobin solutions it can be calculated that the blood oxygen affinity of the rhinoceros must be rather high with a P50 of about 20 torr at pH 7.4 and 37 degrees C, which conforms with observations obtained for other large mammals.

Thermodynamic study of dihydrogen phosphate dimerisation and complexation with novel urea- and thiourea-based receptors.

Science.gov (United States)

Bregović, Nikola; Cindro, Nikola; Frkanec, Leo; Užarević, Krunoslav; Tomišić, Vladislav

2014-11-24

Complexation of dihydrogen phosphate by novel thiourea and urea receptors in acetonitrile and dimethyl sulfoxide was studied in detail by an integrated approach by using several methods (isothermal titration calorimetry, ESI-MS, and (1)H NMR and UV spectroscopy). Thermodynamic investigations into H2PO4(-) dimerisation, which is a process that has been frequently recognised, but rarely quantitatively described, were carried out as well. The corresponding equilibrium was taken into account in the anion-binding studies, which enabled reliable determination of the complexation thermodynamic quantities. In both solvents the thiourea derivatives exhibited considerably higher binding affinities with respect to those containing the urea moiety. In acetonitrile, 1:1 and 2:1 (anion/receptor) complexes formed, whereas in dimethyl sulfoxide only the significantly less stable complexes of 1:1 stoichiometry were detected. The solvent effects on the thermodynamic parameters of dihydrogen phosphate dimerisation and complexation reactions are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Indirect coupling of phosphate release to de novo tension generation during muscle contraction.

Science.gov (United States)

Davis, J S; Rodgers, M E

1995-01-01

A key question in muscle contraction is how tension generation is coupled to the chemistry of the actomyosin ATPase. Biochemical and mechanochemical experiments link tension generation to a change in structure associated with phosphate release. Length-jump and temperature-jump experiments, on the other hand, implicate phase 2slow, a significantly faster, markedly strain-sensitive kinetic process in tension generation. We use a laser temperature jump to probe the kinetics and mechanism of tension generation in skinned rabbit psoas fibers--an appropriate method since both phosphate release and phase 2slow are readily perturbed by temperature. Kinetics characteristic of the structural change associated with phosphate release are observed only when phosphate is added to fibers. When present, it causes a reduction in fiber tension; otherwise, no force is generated when it is perturbed. We therefore exclude this step from tension generation. The kinetics of de novo tension generation by the temperature-jump equivalent of phase 2slow appear unaffected by phosphate binding. We therefore propose that phosphate release is indirectly coupled to de novo tension generation via a steady-state flux through an irreversible step. We conclude that tension generation occurs in the absence of chemical change as the result of an entropy-driven transition between strongly bound crossbridges in the actomyosin-ADP state. The mechanism resembles the operation of a clock, with phosphate release providing the energy to tension the spring, and the irreversible step functions as the escapement mechanism, which is followed in turn by tension generation as the movement of the hands. Images Fig. 6 PMID:7479824

Exposure to tri-o-cresyl phosphate detected in jet airplane passengers

International Nuclear Information System (INIS)

Liyasova, Mariya; Li, Bin; Schopfer, Lawrence M.; Nachon, Florian; Masson, Patrick; Furlong, Clement E.; Lockridge, Oksana

2011-01-01

The aircraft cabin and flight deck ventilation are supplied from partially compressed unfiltered bleed air directly from the engine. Worn or defective engine seals can result in the release of engine oil into the cabin air supply. Aircrew and passengers have complained of illness following such “fume events”. Adverse health effects are hypothesized to result from exposure to tricresyl phosphate mixed esters, a chemical added to jet engine oil and hydraulic fluid for its anti-wear properties. Our goal was to develop a laboratory test for exposure to tricresyl phosphate. The assay was based on the fact that the active-site serine of butyrylcholinesterase reacts with the active metabolite of tri-o-cresyl phosphate, cresyl saligenin phosphate, to make a stable phosphorylated adduct with an added mass of 80 Da. No other organophosphorus agent makes this adduct in vivo on butyrylcholinesterase. Blood samples from jet airplane passengers were obtained 24–48 h after completing a flight. Butyrylcholinesterase was partially purified from 25 ml serum or plasma, digested with pepsin, enriched for phosphorylated peptides by binding to titanium oxide, and analyzed by mass spectrometry. Of 12 jet airplane passengers tested, 6 were positive for exposure to tri-o-cresyl phosphate that is, they had detectable amounts of the phosphorylated peptide FGEpSAGAAS. The level of exposure was very low. No more than 0.05 to 3% of plasma butyrylcholinesterase was modified. None of the subjects had toxic symptoms. Four of the positive subjects were retested 3 to 7 months following their last airplane trip and were found to be negative for phosphorylated butyrylcholinesterase. In conclusion, this is the first report of an assay that detects exposure to tri-o-cresyl phosphate in jet airplane travelers. -- Highlights: ► Travel on jet airplanes is associated with an illness, aerotoxic syndrome. ► A possible cause is exposure to tricresyl phosphate in engine lubricating oil. ► A blood

Exposure to tri-o-cresyl phosphate detected in jet airplane passengers

Energy Technology Data Exchange (ETDEWEB)

Liyasova, Mariya, E-mail: mliyasov@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Department of Environmental, Agricultural, and Occupational Health, University of Nebraska Medical Center, Omaha, NE (United States); Li, Bin, E-mail: binli@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Schopfer, Lawrence M., E-mail: lmschopf@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Nachon, Florian, E-mail: fnachon@nachon.net [Departement de Toxicologie, Institut de Recherche Biomedicale des Armees, 24 avenue des Marquis du Gresivaudan, 38702 La Tronche (France); Masson, Patrick, E-mail: pmasson@unmc.edu [Departement de Toxicologie, Institut de Recherche Biomedicale des Armees, 24 avenue des Marquis du Gresivaudan, 38702 La Tronche (France); Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Furlong, Clement E., E-mail: clem@uw.edu [Department of Medicine (Div. Medical Genetics) and Genome Sciences, University of Washington, Seattle, WA 98195 (United States); Lockridge, Oksana, E-mail: olockrid@unmc.edu [Eppley Institute, University of Nebraska Medical Center, Omaha, NE 68198-5950 (United States); Department of Environmental, Agricultural, and Occupational Health, University of Nebraska Medical Center, Omaha, NE (United States)

2011-11-15

The aircraft cabin and flight deck ventilation are supplied from partially compressed unfiltered bleed air directly from the engine. Worn or defective engine seals can result in the release of engine oil into the cabin air supply. Aircrew and passengers have complained of illness following such 'fume events'. Adverse health effects are hypothesized to result from exposure to tricresyl phosphate mixed esters, a chemical added to jet engine oil and hydraulic fluid for its anti-wear properties. Our goal was to develop a laboratory test for exposure to tricresyl phosphate. The assay was based on the fact that the active-site serine of butyrylcholinesterase reacts with the active metabolite of tri-o-cresyl phosphate, cresyl saligenin phosphate, to make a stable phosphorylated adduct with an added mass of 80 Da. No other organophosphorus agent makes this adduct in vivo on butyrylcholinesterase. Blood samples from jet airplane passengers were obtained 24-48 h after completing a flight. Butyrylcholinesterase was partially purified from 25 ml serum or plasma, digested with pepsin, enriched for phosphorylated peptides by binding to titanium oxide, and analyzed by mass spectrometry. Of 12 jet airplane passengers tested, 6 were positive for exposure to tri-o-cresyl phosphate that is, they had detectable amounts of the phosphorylated peptide FGEpSAGAAS. The level of exposure was very low. No more than 0.05 to 3% of plasma butyrylcholinesterase was modified. None of the subjects had toxic symptoms. Four of the positive subjects were retested 3 to 7 months following their last airplane trip and were found to be negative for phosphorylated butyrylcholinesterase. In conclusion, this is the first report of an assay that detects exposure to tri-o-cresyl phosphate in jet airplane travelers. -- Highlights: Black-Right-Pointing-Pointer Travel on jet airplanes is associated with an illness, aerotoxic syndrome. Black-Right-Pointing-Pointer A possible cause is exposure to

Alpha 1A and alpha 1B-adrenoceptors enhance inositol phosphate generation in rat renal cortex

NARCIS (Netherlands)

Michel, M. C.; Büscher, R.; Philipp, T.; Brodde, O. E.

1993-01-01

We have studied the role of alpha 1A- and alpha 1B-adrenoceptors in noradrenaline- and methoxamine-stimulated inositol phosphate accumulation in rat renal cortical slices. [3H]Prazosin binding studies with and without inactivation of alpha 1B-adrenoceptors by chloroethylclonidine treatment suggested

Turn-on fluorescent sensor for Zinc and Cadmium ions based on quinolone and its sequential response to phosphate

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiaoyan; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xue, Kun [Engineering Laboratory for Flame Retardant and Functional Materials of Hennan Province, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Xu, Kuoxi, E-mail: xukx@henu.edu.cn [Engineering Laboratory for Flame Retardant and Functional Materials of Hennan Province, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

2017-06-15

Sequential fluorescence sensing of Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion by new quinoline based sensors(L1 and L2) have been presented. Sensors exhibit highly selective fluorescence “turn-on” sensing properties to Zn{sup 2+}/Cd{sup 2+} ions in CH{sub 3}OH/H{sub 2}O(1/1, v/v, Tris, 10 mol·L{sup −1}, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H{sub 2}PO{sub 4}{sup -} and HPO{sub 4}{sup 2-} anions through fluorescence “turn-off” respond. The results of Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn{sup 2+}/ Cd{sup 2+} ions and phosphate anion detection in aqueous media. - Graphical abstract: Sequential fluorescence sensing of Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion by new quinoline based sensors (L1 and L2) have been presented. Sensors exhibit highly selective and sensitive fluorescence “turn-on” sensing properties to Zn{sup 2+}/Cd{sup 2+} ions in CH{sub 3}OH/H{sub 2}O(1/1, v/v, Tris, 10 mM, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H{sub 2}PO{sub 4}{sup -} and HPO{sub 4}{sup 2-} anions through fluorescence “turn-off” respond. Zn{sup 2+}/Cd{sup 2+} ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn{sup 2+}/ Cd{sup 2+} ions and phosphate anion detection in aqueous media.

Cleanup of 7.5% tributyl phosphate/n-paraffin solvent-extraction solvent

International Nuclear Information System (INIS)

Reif, D.J.

1987-02-01

The HM process at the Savannah River Plant uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials which influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands which hold fission products in the solvent. Treatment of solvent by an alumina adsorption process removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale alumina adsorption process and the use of the process to clean HM process first cycle solvent is discussed

Structural Analysis of Substrate, Reaction Intermediate, and Product Binding in Haemophilus influenzae Biotin Carboxylase

Science.gov (United States)

Broussard, Tyler C.; Pakhomova, Svetlana; Neau, David B.; Bonnot, Ross; Waldrop, Grover L.

2015-01-01

Acetyl-CoA carboxylase catalyzes the first and regulated step in fatty acid synthesis. In most Gram-negative and Gram-positive bacteria, the enzyme is composed of three proteins: biotin carboxylase, a biotin carboxyl carrier protein (BCCP), and carboxyltransferase. The reaction mechanism involves two half-reactions with biotin carboxylase catalyzing the ATP-dependent carboxylation of biotin-BCCP in the first reaction. In the second reaction, carboxyltransferase catalyzes the transfer of the carboxyl group from biotin-BCCP to acetyl-CoA to form malonyl-CoA. In this report, high-resolution crystal structures of biotin carboxylase from Haemophilus influenzae were determined with bicarbonate, the ATP analogue AMPPCP; the carboxyphosphate intermediate analogues, phosphonoacetamide and phosphonoformate; the products ADP and phosphate; and the carboxybiotin analogue N1′-methoxycarbonyl biotin methyl ester. The structures have a common theme in that bicarbonate, phosphate, and the methyl ester of the carboxyl group of N1′-methoxycarbonyl biotin methyl ester all bound in the same pocket in the active site of biotin carboxylase and as such utilize the same set of amino acids for binding. This finding suggests a catalytic mechanism for biotin carboxylase in which the binding pocket that binds tetrahedral phosphate also accommodates and stabilizes a tetrahedral dianionic transition state resulting from direct transfer of CO2 from the carboxyphosphate intermediate to biotin. PMID:26020841

Phosphorus release from phosphate rock and iron phosphate by low-molecular-weight organic acids.

Science.gov (United States)

Xu, Ren-kou; Zhu, Yong-guan; Chittleborough, David

2004-01-01

Low-molecular-weight(LMW) organic acids widely exist in soils, particularly in the rhizosphere. A series of batch experiments were carried out to investigate the phosphorus release from rock phosphate and iron phosphate by low-molecular-weight organic acids. Results showed that citric acid had the highest capacity to solubilize P from both rock and iron phosphate. P solubilization from rock phosphate and iron phosphate resulted in net proton consumption. P release from rock phosphate was positively correlated with the pKa values. P release from iron phosphate was positively correlated with Fe-organic acid stability constants except for aromatic acids, but was notcorrelated with pKa. Increase in the concentrations of organic acids enhanced P solubilization from both rock and iron phosphate almost linearly. Addition of phenolic compounds further increased the P release from iron phosphate. Initial solution pH had much more substantial effect on P release from rock phosphate than from iron phosphate.

Sugar-binding sites of the HA1 subcomponent of Clostridium botulinum type C progenitor toxin.

Science.gov (United States)

Nakamura, Toshio; Tonozuka, Takashi; Ide, Azusa; Yuzawa, Takayuki; Oguma, Keiji; Nishikawa, Atsushi

2008-02-22

Clostridium botulinum type C 16S progenitor toxin contains a hemagglutinin (HA) subcomponent, designated HA1, which appears to play an important role in the effective internalization of the toxin in gastrointestinal epithelial cells and in creating a broad specificity for the oligosaccharide structure that corresponds to various targets. In this study, using the recombinant protein fused to glutathione S-transferase, we investigated the binding specificity of the HA1 subcomponent to sugars and estimated the binding sites of HA1 based on X-ray crystallography and soaking experiments using various sugars. N-Acetylneuraminic acid, N-acetylgalactosamine, and galactose effectively inhibited the binding that occurs between glutathione S-transferase-HA1 and mucins, whereas N-acetylglucosamine and glucose did not inhibit it. The crystal structures of HA1 complex with N-acetylneuraminic acid, N-acetylgalactosamine, and galactose were also determined. There are two sugar-binding sites, sites I and II. Site I corresponds to the electron densities noted for all sugars and is located at the C-terminal beta-trefoil domain, while site II corresponds to the electron densities noted only for galactose. An aromatic amino acid residue, Trp176, at site I has a stacking interaction with the hexose ring of the sugars. On the other hand, there is no aromatic residue at site II; thus, the interaction with galactose seems to be poor. The double mutant W176A at site I and D271F at site II has no avidity for N-acetylneuraminic acid but has avidity for galactose. In this report, the binding specificity of botulinum C16S toxin HA1 to various sugars is demonstrated based on its structural features.

Characterization of the allosteric binding pocket of human liver fructose-1,6-bisphosphatase by protein crystallography and inhibitor activity studies.

Science.gov (United States)

Iversen, L F; Brzozowski, M; Hastrup, S; Hubbard, R; Kastrup, J S; Larsen, I K; Naerum, L; Nørskov-Lauridsen, L; Rasmussen, P B; Thim, L; Wiberg, F C; Lundgren, K

1997-05-01

The structures of three complexes of human fructose-1,6-bisphosphatase (FB) with the allosteric inhibitor AMP and two AMP analogues have been determined and all fully refined. The data used for structure determination were collected at cryogenic temperature (110 K), and with the use of synchrotron radiation. The structures reveal a common mode of binding for AMP and formycine monophosphate (FMP). 5-Amino-4-carboxamido-1 beta-D-5-phosphate-ribofuranosyl-1H-imidazole (AICAR-P) shows an unexpected mode of binding to FB, different from that of the other two ligands. The imidazole ring of AICAR-P is rotated 180 degrees compared to the AMP and FMP bases. This rotation results in a slightly different hydrogen bonding pattern and minor changes in the water structure in the binding pocket. Common features of binding are seen for the ribose and phosphate moieties of all three compounds. Although binding in a different mode, AICAR-P is still capable of making all the important interactions with the residues building the allosteric binding pocket. The IC50 values of AMP, FMP, and AICAR-P were determined to be 1.7, 1.4, and 20.9 microM, respectively. Thus, the approximately 10 times lower potency of AICAR-P is difficult to explain solely from the variations observed in the binding pocket. Only one water molecule in the allosteric binding pocket was found to be conserved in all four subunits in all three structures. This water molecule coordinates to a phosphate oxygen atom and the N7 atom of the AMP molecule, and to similarly situated atoms in the FMP and AICAR-P complexes. This implies an important role of the conserved water molecule in binding of the ligand.

Modelling phosphate adsorption to the soil: Application of the non-ideal competitive adsorption model

International Nuclear Information System (INIS)

Abou Nohra, Joumana S.; Madramootoo, Chandra A.; Hendershot, William H.

2007-01-01

Phosphorus (P) transport in subsurface runoff has increased despite the limited mobility of P in soils. This study investigated the ability of the non-ideal competitive adsorption (NICA) model to describe phosphate (PO 4 ) adsorption for soils in southern Quebec (Canada). We measured the surface charge and PO 4 adsorption capacity for 11 agricultural soils. Using the experimental data and a nonlinear fitting function, we derived the NICA model parameters. We found that the NICA model described accurately the surface charge of these soils with a mean R 2 > 0.99, and described the adsorption data with a mean R 2 = 0.96. We also found that the variable surface charge was distributed over the two binding sites with the low pH sites demonstrating a stronger binding energy for hydroxyl and PO 4 ions. We established that the NICA model is able to describe P adsorption for the soils considered in this study. - The NICA model accurately described the adsorption of phosphate to some southern Quebec soils

Ternary complex formation of lanthanides and radiolanthanides with phosphate and serum proteins

International Nuclear Information System (INIS)

Neumaier, B.; Roesch, F.

1999-01-01

Radioyttrium was recently reported to form ternary complexes with phosphate and serum proteins in blood. In the present work it was investigated whether the trivalent radiolanthanides react in a chemically similar way. In systematic binding studies using gel filtration a ternary complex formation between different lanthanides, phosphate and serum proteins could be identified. The tendency to build a ternary compound of the type Ln III - phosphate - serum protein, however, is dependent on the ionic radii of the lanthanides. Whereas the light and transition lanthanides have a strong inclination to build a ternary complex, this tendency is weaker for the heavier ones. Taking into account the high content of phosphate in human blood, the corresponding ternary complexes of radiolanthanides represent an important transport form of these elements in blood. This finding may contribute to an understanding of the nuclear medical observation on the biodistribution of radiolanthanides. The heavy radiolanthanides can be classified as bone seeking metals, whereas the light and transition lanthanide elements accumulate mainly in the liver and the spleen. For the lighter radiolanthanides the corresponding ternary complexes thus represent an important transport form in blood. This physicochemical form of lanthanides mainly results in reticulo endothelial accumulation; on the other hand, the lower tendency of heavier lanthanides leads to preferential skeletal deposition. (orig.)

Brittle and ductile adjustable cement derived from calcium phosphate cement/polyacrylic acid composites.

Science.gov (United States)

Chen, Wen-Cheng; Ju, Chien-Ping; Wang, Jen-Chyan; Hung, Chun-Cheng; Chern Lin, Jiin-Huey

2008-12-01

Bone filler has been used over the years in dental and biomedical applications. The present work is to characterize a non-dispersive, fast setting, modulus adjustable, high bioresorbable composite bone cement derived from calcium phosphate-based cement combined with polymer and binding agents. This cement, we hope, will not swell in simulated body fluid and keep the osteogenetic properties of the dry bone and avoid its disadvantages of being brittle. We developed a calcium phosphate cement (CPC) of tetracalcium phosphate/dicalcium phosphate anhydrous (TTCP/DCPA)-polyacrylic acid with tartaric acid, calcium fluoride additives and phosphate hardening solution. The results show that while composite, the hard-brittle properties of 25wt% polyacrylic acid are proportional to CPC and mixing with additives is the same as those of the CPC without polyacrylic acid added. With an increase of polyacrylic acid/CPC ratio, the 67wt% samples revealed ductile-tough properties and 100wt% samples kept ductile or elastic properties after 24h of immersion. The modulus range of this development was from 200 to 2600MPa after getting immersed in simulated body fluid for 24h. The TTCP/DCPA-polyacrylic acid based CPC demonstrates adjustable brittle/ductile strength during setting and after immersion, and the final reaction products consist of high bioresorbable monetite/brushite/calcium fluoride composite with polyacrylic acid.

Interaction of bovine gallbladder mucin and calcium-binding protein: effects on calcium phosphate precipitation

NARCIS (Netherlands)

Afdhal, N. H.; Ostrow, J. D.; Koehler, R.; Niu, N.; Groen, A. K.; Veis, A.; Nunes, D. P.; Offner, G. D.

1995-01-01

Gallstones consist of calcium salts and cholesterol crystals, arrayed on a matrix of gallbladder mucin (GBM), and regulatory proteins like calcium-binding protein (CBP). To determine if interactions between CBP and GBM follow a biomineralization scheme, their mutual binding and effects on CaHPO4

Lithium-Ion Mobility in Quaternary Boro-Germano-Phosphate Glasses.

Science.gov (United States)

Moguš-Milanković, Andrea; Sklepić, Kristina; Mošner, Petr; Koudelka, Ladislav; Kalenda, Petr

2016-04-28

Effect of the structural changes, electrical conductivity, and dielectric properties on the addition of a third glass-former, GeO2, to the borophosphate glasses, 40Li2O-10B2O3-(50 - x)P2O5-xGeO2, x = 0-25 mol %, has been studied. Introduction of GeO2 causes the structural modifications in the glass network, which results in a continuous increase in electrical conductivity. Glasses with low GeO2 content, up to 10 mol %, show a rapid increase in dc conductivity as a result of the interlinkage of slightly depolymerized phosphate chains and negatively charged [GeO4](-) units, which enhances the migration of Li(+) ions. The Li(+) ions compensate these delocalized charges connecting both phosphate and germanium units, which results in reduction of both bond effectiveness and binding energy of Li(+) ions and therefore enables their hop to the next charge-compensating site. For higher GeO2 content, the dc conductivity increases slightly, tending to approach a maximum in Li(+) ion mobility caused by the incorporation of GeO2 units into phosphate network combined with conversion of GeO4 to GeO6 units. The strong cross-linkage of germanium and phosphate units creates heteroatomic P-O-Ge bonds responsible for more effectively trapped Li(+) ions. A close correspondence between dielectric and conductivity parameters at high frequencies indicates that the increase in conductivity indeed is controlled by the modification of structure as a function of GeO2 addition.

Phosphorus Binding Sites in Proteins: Structural Preorganization and Coordination

DEFF Research Database (Denmark)

Gruber, Mathias Felix; Greisen, Per Junior; Junker, Märta Caroline

2014-01-01

to individual structures that bind to phosphate groups; here, we investigate a total of 8307 structures obtained from the RCSB Protein Data Bank (PDB). An analysis of the binding site amino acid propensities reveals very characteristic first shell residue distributions, which are found to be influenced...... by the characteristics of the phosphorus compound and by the presence of cobound cations. The second shell, which supports the coordinating residues in the first shell, is found to consist mainly of protein backbone groups. Our results show how the second shell residue distribution is dictated mainly by the first shell...

Diagnosis and epidemiology of red blood cell enzyme disorders

Directory of Open Access Journals (Sweden)

Richard Van Wijk

2013-03-01

Full Text Available The red blood cell possess an active metabolic machinery that provides the cell with energy to pump ions against electrochemical gradients, to maintain its shape, to keep hemoglobin iron in the reduced (ferrous form, and to maintain enzyme and hemoglobin sulfhydryl groups. The main source of metabolic energy comes from glucose. Glucose is metabolized through the glycolytic pathway and through the hexose monophosphate shunt. Glycolysis catabolizes glucose to pyruvate and lactate, which represent the end products of glucose metabolism in the erythrocyte. Adenosine diphosphate (ADP is phosphorylated to adenosine triphosphate (ATP, and nicotinamide adenine dinucleotide (NAD+ is reduced to NADH in glycolysis. 2,3- Bisphosphoglycerate, an important regulator of the oxygen affinity of hemoglobin, is generated during glycolysis by the Rapoport-Luebering shunt. The hexose monophosphate shunt oxidizes glucose-6-phosphate, reducing NADP+ to reduced nicotinamide adenine dinucleotide phosphate (NADPH. The red cell lacks the capacity for de novo purine synthesis but has a salvage pathway that permits synthesis of purine nucleotides from purine bases...

Exposure to tri-o-cresyl phosphate detected in jet airplane passengers.

Science.gov (United States)

Liyasova, Mariya; Li, Bin; Schopfer, Lawrence M; Nachon, Florian; Masson, Patrick; Furlong, Clement E; Lockridge, Oksana

2011-11-01

The aircraft cabin and flight deck ventilation are supplied from partially compressed unfiltered bleed air directly from the engine. Worn or defective engine seals can result in the release of engine oil into the cabin air supply. Aircrew and passengers have complained of illness following such "fume events". Adverse health effects are hypothesized to result from exposure to tricresyl phosphate mixed esters, a chemical added to jet engine oil and hydraulic fluid for its anti-wear properties. Our goal was to develop a laboratory test for exposure to tricresyl phosphate. The assay was based on the fact that the active-site serine of butyrylcholinesterase reacts with the active metabolite of tri-o-cresyl phosphate, cresyl saligenin phosphate, to make a stable phosphorylated adduct with an added mass of 80 Da. No other organophosphorus agent makes this adduct in vivo on butyrylcholinesterase. Blood samples from jet airplane passengers were obtained 24-48 h after completing a flight. Butyrylcholinesterase was partially purified from 25 ml serum or plasma, digested with pepsin, enriched for phosphorylated peptides by binding to titanium oxide, and analyzed by mass spectrometry. Of 12 jet airplane passengers tested, 6 were positive for exposure to tri-o-cresyl phosphate that is, they had detectable amounts of the phosphorylated peptide FGEpSAGAAS. The level of exposure was very low. No more than 0.05 to 3% of plasma butyrylcholinesterase was modified. None of the subjects had toxic symptoms. Four of the positive subjects were retested 3 to 7 months following their last airplane trip and were found to be negative for phosphorylated butyrylcholinesterase. In conclusion, this is the first report of an assay that detects exposure to tri-o-cresyl phosphate in jet airplane travelers. Copyright © 2011 Elsevier Inc. All rights reserved.

Reevaluation of the phenol-sulfuric acid reaction for the estimation of hexoses and pentoses.

Science.gov (United States)

Rao, P; Pattabiraman, T N

1989-08-15

Evidence is provided to show that in the conventional phenol-sulfuric acid reaction procedure, phenol underwent sulfonation in situ and the phenolsulfonic acid formed decreased the color intensity for hydroxymethyl furfural (HMF), furfural, and many hexoses and pentoses tested. A modified method is described to overcome this problem in which phenol was added after the dehydration of carbohydrates by sulfuric acid and after cooling the system. The color intensity around 475-485 nm for different compounds was fairly proportional to the amount of furfural derivatives (absorption at 310-320 nm) formed from the sugars in the modified method unlike in the conventional procedure. The studies also show that for condensation of HMF derivatives with phenol, heat is not necessary. The color intensity in the modified method also increased compared to that in the conventional method. The increase in the modified method compared to that in the conventional method was 6.0-fold for furfural, 9.1-fold for hydroxymethyl furfural, 3.7-fold for fructose, 2.3-fold for xylose, and 2.0-fold for glucose and arabinose. The possible reasons for this differential increase are discussed.

Removal of phosphate from solution by adsorption and precipitation of calcium phosphate onto monohydrocalcite.

Science.gov (United States)

Yagi, Shintaro; Fukushi, Keisuke

2012-10-15

The sorption behavior and mechanism of phosphate on monohydrocalcite (CaCO(3)·H(2)O: MHC) were examined using batch sorption experiments as a function of phosphate concentrations, ionic strengths, temperatures, and reaction times. The mode of PO(4) sorption is divisible into three processes depending on the phosphate loading. At low phosphate concentrations, phosphate is removed by coprecipitation of phosphate during the transformation of MHC to calcite. The sorption mode at the low-to-moderate phosphate concentrations is most likely an adsorption process because the sorption isotherm at the conditions can be fitted reasonably with the Langmuir equation. The rapid sorption kinetics at the conditions is also consistent with the adsorption reaction. The adsorption of phosphate on MHC depends strongly on ionic strength, but slightly on temperature. The maximum adsorption capacities of MHC obtained from the regression of the experimental data to the Langmuir equation are higher than those reported for stable calcium carbonate (calcite or aragonite) in any conditions. At high phosphate concentrations, the amount of sorption deviates from the Langmuir isotherm, which can fit the low-to-moderate phosphate concentrations. Speciation-saturation analyses of the reacted solutions at the conditions indicated that the solution compositions which deviate from the Langmuir equation are supersaturated with respect to a certain calcium phosphate. The obtained calcium phosphate is most likely amorphous calcium phosphate (Ca(3)(PO(4))(2)·xH(2)O). The formation of the calcium phosphate depends strongly on ionic strength, temperature, and reaction times. The solubility of MHC is higher than calcite and aragonite because of its metastability. Therefore, the higher solubility of MHC facilitates the formation of the calcium phosphates more than with calcite and aragonite. Copyright © 2012 Elsevier Inc. All rights reserved.

Influence of fructose on the diffusion of potassium hydrogen phosphate in aqueous solutions at 25 °C

International Nuclear Information System (INIS)

Verissimo, Luis M.P.; Teigão, Joana M.M.; Ramos, M. Luísa; Burrows, Hugh D.; Esteso, Miguel A.; Ribeiro, Ana C.F.

2016-01-01

Highlights: • Diffusion coefficients of aqueous systems of fructose and potassium hydrogen phosphate measured with Lobo’s cell. • Influence of the fructose on the diffusion of potassium hydrogen phosphate. • Interactions between of hydrogen phosphate anion and fructose. - Abstract: Diffusion coefficients have been measured at 25 °C for potassium hydrogen phosphate (K_2HPO_4, 0.101 mol kg"−"1) in aqueous solutions containing various concentrations of fructose from (0.001 to 0.101) mol kg"−"1, using a conductimetric cell (the Lobo cell) coupled to an automatic data acquisition system. Significant effects of fructose were observed on the diffusion of K_2HPO_4 in these mixtures, which are attributed to the interaction between HPO_4"2"− anion (or other protonated forms) and fructose. Support for this comes from "1H and "1"3C NMR spectroscopy, which are compatible with binding between the anomeric forms of D-fructose and the HPO_4"2"− anion.

Patterns of binding of aluminum-containing adjuvants to Haemophilus influenzae type b and meningococcal group C conjugate vaccines and components

Science.gov (United States)

Otto, Robert B.D.; Burkin, Karena; Amir, Saba Erum; Crane, Dennis T.; Bolgiano, Barbara

2015-01-01

The basis of Haemophilus influenzae type b (Hib) and Neisseria meningitidis serogroup C (MenC) glycoconjugates binding to aluminum-containing adjuvants was studied. By measuring the amount of polysaccharide and protein in the non-adsorbed supernatant, the adjuvant, aluminum phosphate, AlPO4, was found to be less efficient than aluminum hydroxide, Al(OH)3 at binding to the conjugates, at concentrations relevant to licensed vaccine formulations and when equimolar. At neutral pH, binding of TT conjugates to AlPO4 was facilitated through the carrier protein, with only weak binding of AlPO4 to CRM197 being observed. There was slightly higher binding of either adjuvant to tetanus toxoid conjugates, than to CRM197 conjugates. This was verified in AlPO4 formulations containing DTwP–Hib, where the adsorption of TT-conjugated Hib was higher than CRM197-conjugated Hib. At neutral pH, the anionic Hib and MenC polysaccharides did not appreciably bind to AlPO4, but did bind to Al(OH)3, due to electrostatic interactions. Phosphate ions reduced the binding of the conjugates to the adjuvants. These patterns of adjuvant adsorption can form the basis for future formulation studies with individual and combination vaccines containing saccharide-protein conjugates. PMID:26194164

Phosphate Recovery From Sewage Sludge Containing Iron Phosphate

NARCIS (Netherlands)

Wilfert, P.K.

2018-01-01

The scope of this thesis was to lay the basis for a phosphate recovery technology that can be applied on sewage sludge containing iron phosphate. Such a technology should come with minimal changes to the existing sludge treatment configuration while keeping the use of chemicals or energy as small as

Ophthalmic acid accumulation in an Escherichia coli mutant lacking the conserved pyridoxal 5'-phosphate-binding protein YggS.

Science.gov (United States)

Ito, Tomokazu; Yamauchi, Ayako; Hemmi, Hisashi; Yoshimura, Tohru

2016-12-01

Escherichia coli YggS is a highly conserved pyridoxal 5'-phosphate (PLP)-binding protein whose biochemical function is currently unknown. A previous study with a yggS-deficient E. coli strain (ΔyggS) demonstrated that YggS controls l-Ile- and l-Val-metabolism by modulating 2-ketobutyrate (2-KB), l-2-aminobutyrate (l-2-AB), and/or coenzyme A (CoA) availability in a PLP-dependent fashion. In this study, we found that ΔyggS accumulates an unknown metabolite as judged by amino acid analyses. LC/MS and MS/MS analyses of the compound with propyl chloroformate derivatization, and co-chromatography analysis identified this compound as γ-l-glutamyl-l-2-aminobutyryl-glycine (ophthalmic acid), a glutathione (GSH) analogue in which the l-Cys moiety is replaced by l-2-AB. We also determine the metabolic consequence of the yggS mutation. Absence of YggS initially increases l-2-AB availability, and then causes ophthalmic acid accumulation and CoA limitation in the cell. The expression of a γ-glutamylcysteine synthetase and a glutathione synthetase in a ΔyggS background causes high-level accumulation of ophthalmic acid in the cells (∼1.2 nmol/mg cells) in a minimal synthetic medium. This opens the possibility of a first fermentative production of ophthalmic acid. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

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

1987-01-01

The binding of inorganic vanadate (V/sub i/) to rabbit muscle phosphoglycerate mutase (PGM), studied by using 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 -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 μM V/sub i/ has little effect on the phosphatase activity. However, in the presence of 25 μM 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

ATP-binding Cassette (ABC) Transport System Solute-binding Protein-guided Identification of Novel d-Altritol and Galactitol Catabolic Pathways in Agrobacterium tumefaciens C58*

Science.gov (United States)

Wichelecki, Daniel J.; Vetting, Matthew W.; Chou, Liyushang; Al-Obaidi, Nawar; Bouvier, Jason T.; Almo, Steven C.; Gerlt, John A.

2015-01-01

Innovations in the discovery of the functions of uncharacterized proteins/enzymes have become increasingly important as advances in sequencing technology flood protein databases with an exponentially growing number of open reading frames. This study documents one such innovation developed by the Enzyme Function Initiative (EFI; U54GM093342), the use of solute-binding proteins for transport systems to identify novel metabolic pathways. In a previous study, this strategy was applied to the tripartite ATP-independent periplasmic transporters. Here, we apply this strategy to the ATP-binding cassette transporters and report the discovery of novel catabolic pathways for d-altritol and galactitol in Agrobacterium tumefaciens C58. These efforts resulted in the description of three novel enzymatic reactions as follows: 1) oxidation of d-altritol to d-tagatose via a dehydrogenase in Pfam family PF00107, a previously unknown reaction; 2) phosphorylation of d-tagatose to d-tagatose 6-phosphate via a kinase in Pfam family PF00294, a previously orphan EC number; and 3) epimerization of d-tagatose 6-phosphate C-4 to d-fructose 6-phosphate via a member of Pfam family PF08013, another previously unknown reaction. The epimerization reaction catalyzed by a member of PF08013 is especially noteworthy, because the functions of members of PF08013 have been unknown. These discoveries were assisted by the following two synergistic bioinformatics web tools made available by the Enzyme Function Initiative: the EFI-Enzyme Similarity Tool and the EFI-Genome Neighborhood Tool. PMID:26472925

Donor assists acceptor binding and catalysis of human α1,6-fucosyltransferase.

Science.gov (United States)

Kötzler, Miriam P; Blank, Simon; Bantleon, Frank I; Wienke, Martin; Spillner, Edzard; Meyer, Bernd

2013-08-16

α1,6-Core-fucosyltransferase (FUT8) is a vital enzyme in mammalian physiological and pathophysiological processes such as tumorigenesis and progress of, among others, non-small cell lung cancer and colon carcinoma. It was also shown that therapeutic antibodies have a dramatically higher efficacy if the α1,6-fucosyl residue is absent. However, specific and potent inhibitors for FUT8 and related enzymes are lacking. Hence, it is crucial to elucidate the structural basis of acceptor binding and the catalytic mechanism. We present here the first structural model of FUT8 in complex with its acceptor and donor molecules. An unusually large acceptor, i.e., a hexasaccharide from the core of N-glycans, is required as minimal structure. Acceptor substrate binding of FUT8 is being dissected experimentally by STD NMR and SPR and theoretically by molecular dynamics simulations. The acceptor binding site forms an unusually large and shallow binding site. Binding of the acceptor to the enzyme is much faster and stronger if the donor is present. This is due to strong hydrogen bonding between O6 of the proximal N-acetylglucosamine and an oxygen atom of the β-phosphate of GDP-fucose. Therefore, we propose an ordered Bi Bi mechanism for FUT8 where the donor molecule binds first. No specific amino acid is present that could act as base during catalysis. Our results indicate a donor-assisted mechanism, where an oxygen of the β-phosphate deprotonates the acceptor. Knowledge of the mechanism of FUT8 is now being used for rational design of targeted inhibitors to address metastasis and prognosis of carcinomas.

Incorporation of phosphate into glycogen by glycogen synthase.

Science.gov (United States)

Contreras, Christopher J; Segvich, Dyann M; Mahalingan, Krishna; Chikwana, Vimbai M; Kirley, Terence L; Hurley, Thomas D; DePaoli-Roach, Anna A; Roach, Peter J

2016-05-01

The storage polymer glycogen normally contains small amounts of covalently attached phosphate as phosphomonoesters at C2, C3 and C6 atoms of glucose residues. In the absence of the laforin phosphatase, as in the rare childhood epilepsy Lafora disease, the phosphorylation level is elevated and is associated with abnormal glycogen structure that contributes to the pathology. Laforin therefore likely functions in vivo as a glycogen phosphatase. The mechanism of glycogen phosphorylation is less well-understood. We have reported that glycogen synthase incorporates phosphate into glycogen via a rare side reaction in which glucose-phosphate rather than glucose is transferred to a growing polyglucose chain (Tagliabracci et al. (2011) Cell Metab13, 274-282). We proposed a mechanism to account for phosphorylation at C2 and possibly at C3. Our results have since been challenged (Nitschke et al. (2013) Cell Metab17, 756-767). Here we extend the evidence supporting our conclusion, validating the assay used for the detection of glycogen phosphorylation, measurement of the transfer of (32)P from [β-(32)P]UDP-glucose to glycogen by glycogen synthase. The (32)P associated with the glycogen fraction was stable to ethanol precipitation, SDS-PAGE and gel filtration on Sephadex G50. The (32)P-signal was not affected by inclusion of excess unlabeled UDP before analysis or by treatment with a UDPase, arguing against the signal being due to contaminating [β-(32)P]UDP generated in the reaction. Furthermore, [(32)P]UDP did not bind non-covalently to glycogen. The (32)P associated with glycogen was released by laforin treatment, suggesting that it was present as a phosphomonoester. The conclusion is that glycogen synthase can mediate the introduction of phosphate into glycogen, thereby providing a possible mechanism for C2, and perhaps C3, phosphorylation. Copyright © 2016 Elsevier Inc. All rights reserved.

Phosphate-a poison for humans?

Science.gov (United States)

Komaba, Hirotaka; Fukagawa, Masafumi

2016-10-01

Maintenance of phosphate balance is essential for life, and mammals have developed a sophisticated system to regulate phosphate homeostasis over the course of evolution. However, due to the dependence of phosphate elimination on the kidney, humans with decreased kidney function are likely to be in a positive phosphate balance. Phosphate excess has been well recognized as a critical factor in the pathogenesis of mineral and bone disorders associated with chronic kidney disease, but recent investigations have also uncovered toxic effects of phosphate on the cardiovascular system and the aging process. Compelling evidence also suggests that increased fibroblastic growth factor 23 and parathyroid hormone levels in response to a positive phosphate balance contribute to adverse clinical outcomes. These insights support the current practice of managing serum phosphate in patients with advanced chronic kidney disease, although definitive evidence of these effects is lacking. Given the potential toxicity of excess phosphate, the general population may also be viewed as a target for phosphate management. However, the widespread implementation of dietary phosphate intervention in the general population may not be warranted due to the limited impact of increased phosphate intake on mineral metabolism and clinical outcomes. Nonetheless, the increasing incidence of kidney disease or injury in our aging society emphasizes the potential importance of this issue. Further work is needed to more completely characterize phosphate toxicity and to establish the optimal therapeutic strategy for managing phosphate in patients with chronic kidney disease and in the general population. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Transcription of lncRNA prt, clustered prt RNA sites for Mmi1 binding, and RNA polymerase II CTD phospho-sites govern the repression of pho1 gene expression under phosphate-replete conditions in fission yeast.

Science.gov (United States)

Chatterjee, Debashree; Sanchez, Ana M; Goldgur, Yehuda; Shuman, Stewart; Schwer, Beate

2016-07-01

Expression of fission yeast Pho1 acid phosphatase is repressed during growth in phosphate-rich medium. Repression is mediated by transcription of the prt locus upstream of pho1 to produce a long noncoding (lnc) prt RNA. Repression is also governed by RNA polymerase II CTD phosphorylation status, whereby inability to place a Ser7-PO4 mark (as in S7A) derepresses Pho1 expression, and inability to place a Thr4-PO4 mark (as in T4A) hyper-represses Pho1 in phosphate replete cells. Here we find that basal pho1 expression from the prt-pho1 locus is inversely correlated with the activity of the prt promoter, which resides in a 110-nucleotide DNA segment preceding the prt transcription start site. CTD mutations S7A and T4A had no effect on the activity of the prt promoter or the pho1 promoter, suggesting that S7A and T4A affect post-initiation events in prt lncRNA synthesis that make it less and more repressive of pho1, respectively. prt lncRNA contains clusters of DSR (determinant of selective removal) sequences recognized by the YTH-domain-containing protein Mmi1. Altering the nucleobase sequence of two DSR clusters in the prt lncRNA caused hyper-repression of pho1 in phosphate replete cells, concomitant with increased levels of the prt transcript. The isolated Mmi1 YTH domain binds to RNAs with single or tandem DSR elements, to the latter in a noncooperative fashion. We report the 1.75 Å crystal structure of the Mmi1 YTH domain and provide evidence that Mmi1 recognizes DSR RNA via a binding mode distinct from that of structurally homologous YTH proteins that recognize m(6)A-modified RNA. © 2016 Chatterjee et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Triphenyl phosphate allergy from spectacle frames

DEFF Research Database (Denmark)

Carlsen, L; Andersen, K E; Egsgaard, Helge

1986-01-01

A case of triphenyl phosphate allergy from spectacle frames is reported. Patch tests with analytical grade triphenyl phosphate, tri-m-cresyl phosphate, and tri-p-cresyl phosphate in the concentrations 5%, 0.5% and 0.05% pet. showed positive reactions to 0.05% triphenyl phosphate and 0.5% tri......-m-cresyl phosphate, but no reaction to tri-p-cresyl phosphate. Gas chromatography of the tricresyl phosphate 5% pet. patch test material supplied from Trolab showed that it contained a mixture of a wide range of triaryl phosphates, including 0.08% triphenyl phosphate which is above the threshold for detecting...

Effect of medium acidity on the thermodynamics and kinetics of the reaction of pyridoxal 5'-phosphate with isoniazid in an aqueous solution

Science.gov (United States)

Gamov, G. A.; Zavalishin, M. N.; Usacheva, T. R.; Sharnin, V. A.

2017-05-01

Thermodynamic characteristics of the formation of the Schiff base between isoniazid and pyridoxal 5'-phosphate in an aqueous solution at different pH values of a medium are determined by means of spectrophotometry and calorimetric titration. The process kinetics is studied spectrophotometrically, and the reaction rate constants for the formation of the imine at different acidities of a medium are determined. Biochemical aspects of the binding of pyridoxal 5'-phosphate into stable compounds are discussed.

Formation and characterization of iron-binding phosphorylated human-like collagen as a potential iron supplement

International Nuclear Information System (INIS)

Deng, Jianjun; Chen, Fei; Fan, Daidi; Zhu, Chenhui; Ma, Xiaoxuan; Xue, Wenjiao

2013-01-01

Iron incorporated into food can induce precipitation and unwanted interaction with other components in food. Iron-binding proteins represent a possibility to avoid these problems and other side effects, as the iron is protected. However, there are several technical problems associated with protein–iron complex formation. In this paper, the iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared under physiological conditions through phosphorylated modification. One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. Spectroscopy analysis, differential scanning calorimetry (DSC) and equilibrium dialysis techniques were employed to investigate the characteristics of the Fe-G6P-HLC. The binding sites (n b ) and apparent association constant (K app ) between iron and phosphorylated HLC were measured at n b = 23.7 and log K app = 4.57, respectively. The amount of iron (Fe 2+ sulfate) binding to phosphorylated HLC was found to be a function of pH and phosphate content. In addition, the solubility and thermal stability of HLC were not significantly affected. The results should facilitate the utilization of HLC as a bioactive iron supplement in the food and medical industry and provide an important theoretical evidence for the application of HLC chelates. - Highlights: • The iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared. • One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. • The binding properties could be modulated through alterations in pH and phosphate content presented in HLC. • A novel strategy for preparing iron-binding proteins was provided

A Pyranose-2-Phosphate Motif Is Responsible for Both Antibiotic Import and Quorum-Sensing Regulation in Agrobacterium tumefaciens.

Directory of Open Access Journals (Sweden)

Abbas El Sahili

2015-08-01

Full Text Available Periplasmic binding proteins (PBPs in association with ABC transporters select and import a wide variety of ligands into bacterial cytoplasm. They can also take up toxic molecules, as observed in the case of the phytopathogen Agrobacterium tumefaciens strain C58. This organism contains a PBP called AccA that mediates the import of the antibiotic agrocin 84, as well as the opine agrocinopine A that acts as both a nutrient and a signalling molecule for the dissemination of virulence genes through quorum-sensing. Here, we characterized the binding mode of AccA using purified agrocin 84 and synthetic agrocinopine A by X-ray crystallography at very high resolution and performed affinity measurements. Structural and affinity analyses revealed that AccA recognizes an uncommon and specific motif, a pyranose-2-phosphate moiety which is present in both imported molecules via the L-arabinopyranose moiety in agrocinopine A and the D-glucopyranose moiety in agrocin 84. We hypothesized that AccA is a gateway allowing the import of any compound possessing a pyranose-2-phosphate motif at one end. This was structurally and functionally confirmed by experiments using four synthetic compounds: agrocinopine 3'-O-benzoate, L-arabinose-2-isopropylphosphate, L-arabinose-2-phosphate and D-glucose-2-phosphate. By combining affinity measurements and in vivo assays, we demonstrated that both L-arabinose-2-phosphate and D-glucose-2-phosphate, which are the AccF mediated degradation products of agrocinopine A and agrocin 84 respectively, interact with the master transcriptional regulator AccR and activate the quorum-sensing signal synthesis and Ti plasmid transfer in A. tumefaciens C58. Our findings shed light on the role of agrocinopine and antibiotic agrocin 84 on quorum-sensing regulation in A. tumefaciens and reveal how the PBP AccA acts as vehicle for the importation of both molecules by means of a key-recognition motif. It also opens future possibilities for the

A Pyranose-2-Phosphate Motif Is Responsible for Both Antibiotic Import and Quorum-Sensing Regulation in Agrobacterium tumefaciens.

Science.gov (United States)

El Sahili, Abbas; Li, Si-Zhe; Lang, Julien; Virus, Cornelia; Planamente, Sara; Ahmar, Mohammed; Guimaraes, Beatriz G; Aumont-Nicaise, Magali; Vigouroux, Armelle; Soulère, Laurent; Reader, John; Queneau, Yves; Faure, Denis; Moréra, Solange

2015-08-01

Periplasmic binding proteins (PBPs) in association with ABC transporters select and import a wide variety of ligands into bacterial cytoplasm. They can also take up toxic molecules, as observed in the case of the phytopathogen Agrobacterium tumefaciens strain C58. This organism contains a PBP called AccA that mediates the import of the antibiotic agrocin 84, as well as the opine agrocinopine A that acts as both a nutrient and a signalling molecule for the dissemination of virulence genes through quorum-sensing. Here, we characterized the binding mode of AccA using purified agrocin 84 and synthetic agrocinopine A by X-ray crystallography at very high resolution and performed affinity measurements. Structural and affinity analyses revealed that AccA recognizes an uncommon and specific motif, a pyranose-2-phosphate moiety which is present in both imported molecules via the L-arabinopyranose moiety in agrocinopine A and the D-glucopyranose moiety in agrocin 84. We hypothesized that AccA is a gateway allowing the import of any compound possessing a pyranose-2-phosphate motif at one end. This was structurally and functionally confirmed by experiments using four synthetic compounds: agrocinopine 3'-O-benzoate, L-arabinose-2-isopropylphosphate, L-arabinose-2-phosphate and D-glucose-2-phosphate. By combining affinity measurements and in vivo assays, we demonstrated that both L-arabinose-2-phosphate and D-glucose-2-phosphate, which are the AccF mediated degradation products of agrocinopine A and agrocin 84 respectively, interact with the master transcriptional regulator AccR and activate the quorum-sensing signal synthesis and Ti plasmid transfer in A. tumefaciens C58. Our findings shed light on the role of agrocinopine and antibiotic agrocin 84 on quorum-sensing regulation in A. tumefaciens and reveal how the PBP AccA acts as vehicle for the importation of both molecules by means of a key-recognition motif. It also opens future possibilities for the rational design of

Preferable removal of phosphate from water using hydrous zirconium oxide-based nanocomposite of high stability.

Science.gov (United States)

Chen, Liang; Zhao, Xin; Pan, Bingcai; Zhang, Weixian; Hua, Ming; Lv, Lu; Zhang, Weiming

2015-03-02

In this study, we employed a new nanocomposite adsorbent HZO-201, which featured high stability under varying solution chemistry, for preferable removal of phosphate from synthetic solution and a real effluent. An anion exchange resin (D-201) was employed as the host of HZO-201, where nano-hydrous zirconium oxide (HZO) was encapsulated as the active species. D-201 binds phosphate through nonspecific electrostatic affinity, whereas the loaded HZO nanoparticles capture phosphate through formation of the inner-sphere complexes. Quantitative contribution of both species to phosphate adsorption was predicted based on the double-Langmuir model. Preferable removal of phosphate by HZO-201 was observed in the presence of the competing anions at higher levels (Cl(-), NO3(-), SO4(2-), HCO3(-)). Fixed-bed adsorption indicated that the effective volume capacity of a synthetic water (2.0 mg P-PO4(3-)/L) by using HZO-201 was ∼1600 BV in the first run (<0.5mg P-PO4(3-)/L), comparable to Fe(III)-based nanocomposite HFO-201 (∼1500 BV) and much larger than D-201 (<250 BV). The exhausted HZO-201 can be in situ regenerated by using a binary NaOH-NaCl solution for cyclic runs, whether fed with the synthetic solution or real effluent. In general, HZO-201 is a promising alternative to Fe(III)-based adsorbents for trace phosphate removal from effluent particularly at acidic pH. Copyright © 2014 Elsevier B.V. All rights reserved.

Feasibility of a tetracycline-binding method for detecting synovial fluid basic calcium phosphate crystals.

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Rosenthal, Ann K; Fahey, Mark; Gohr, Claudia; Burner, Todd; Konon, Irina; Daft, Laureen; Mattson, Eric; Hirschmugl, Carol; Ryan, Lawrence M; Simkin, Peter

2008-10-01

Basic calcium phosphate (BCP) crystals are common components of osteoarthritis (OA) synovial fluid. Progress in understanding the role of these bioactive particles in clinical OA has been hampered by difficulties in their identification. Tetracyclines stain calcium phosphate mineral in bone. The aim of this study was to investigate whether tetracycline staining might be an additional or alternative method for identifying BCP crystals in synovial fluid. A drop of oxytetracycline was mixed with a drop of fluid containing synthetic or native BCP, calcium pyrophosphate dihydrate (CPPD), or monosodium urate (MSU) crystals and placed on a microscope slide. Stained and unstained crystals were examined by light microscopy, with and without a portable broad-spectrum ultraviolet (UV) pen light. A small set of characterized synovial fluid samples were compared by staining with alizarin red S and oxytetracycline. Synthetic BCP crystals in synovial fluid were quantified fluorimetrically using oxytetracycline. After oxytetracycline staining, synthetic and native BCP crystals appeared as fluorescent amorphous aggregates under UV light. Oxytetracycline did not stain CPPD or MSU crystals or other particulates. Oxytetracycline staining had fewer false-positive test results than did alizarin red S staining and could provide estimates of the quantities of synthetic BCP crystals in synovial fluid. With further validation, oxytetracycline staining may prove to be a useful adjunct or alternative to currently available methods for identifying BCP crystals in synovial fluid.

The binding of glucose and nucleotides to hexokinase from Saccharomyces cerevisiae.

Science.gov (United States)

Woolfitt, A R; Kellett, G L; Hoggett, J G

1988-01-29

The binding of glucose, ADP and AdoPP[NH]P, to the native PII dimer and PII monomer and the proteolytically-modified SII monomer of hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) from Saccharomyces cerevisiae was monitored at pH 6.7 by the concomitant quenching of protein fluorescence. The data were analysed in terms of Qmax, the maximal quenching of fluorescence at saturating concentrations of ligand, and [L]0.5, the concentration of ligand at half-maximal quenching. No changes in fluorescence were observed with free enzyme and nucleotide alone. In the presence of saturating levels of glucose, Qmax induced by nucleotide was between 2 and 7%, and [L]0.5 was between 0.12 and 0.56 mM, depending on the nucleotide and enzyme species. Qmax induced by glucose alone was between 22 and 25%, while [L]0.5 was approx. 0.4 mM for either of the monomeric hexokinase forms and 3.4 for PII dimer. In the presence of 6 mM ADP or 2 mM AdoPP[NH]P, Qmax for glucose was increased by up to 4% and [L]0.5 was diminished 3-fold for hexokinase PII monomer, 6-fold for SII monomer, and 15-fold for PII dimer. The results are interpreted in terms of nucleotide-induced conformational change of hexokinase in the presence of glucose and synergistic binding interactions between glucose and nucleotide.

[Glucose-6-phosphatase from nuclear envelope in rat liver].

Science.gov (United States)

González-Mujica, Freddy

2008-06-01

Nuclear envelope (NE) and microsomal glucosa-6-phosphatase (G-6-Pase) activities were compared. Intact microsomes were unable to hydrolyze mannose-6-phosphate (M-6-P), on the other hand, intact NE hydrolyzes this substrate. Galactose-6-phosphate showed to be a good substrate for both NE and microsomal enzymes, with similar latency to that obtained with M-6-P using microsomes. In consequence, this substrate was used to measure the NE integrity. The kinetic parameters (Kii and Kis) of the intact NE G-6-Pase for the phlorizin inhibition using glucose-6-phosphate (G-6-P) and M-6-P as substrates, were very similar. The NE T1 transporter was more sensitive to amiloride than the microsomal T1. The microsomal system was more sensitive to N-ethylmalemide (NEM) than the NE and the latter was insensitive to anion transport inhibitors DIDS and SITS, which strongly affect the microsomal enzyme. The above results allowed to postulate the presence of a hexose-6-phosphate transporter in the NE which is able to carry G-6-P and M-6-P, and perhaps other hexose-6-phosphate which could be different from that present in microsomes or, if it is the same, its activity could by modified by the membrane system where it is included. The higher PPi hydrolysis activity of the intact NE G-6-Pase in comparison to the intact microsomal, suggests differences between the Pi/PPi transport (T2) of both systems. The lower sensitivity of the NE G-6-Pase to NEM suggests that the catalytic subunit of this system has some differences with the microsomal isoform.

Performance of pineapple slips inoculated with diazotrophic phosphate-solubilizing bacteria and rock phosphate

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Lílian Estrela Borges Baldotto

2014-06-01

Full Text Available Besides fixing N2, some diazotrophic bacteria or diazotrophs, also synthesize organic acids and are able to solubilize rock phosphates, increasing the availability of P for plants. The application of these bacteria to pineapple leaf axils in combination with rock phosphate could increase N and P availability for the crop, due to the bacterial activity of biological nitrogen fixation and phosphate solubilization. The objectives of this study were: (i to select and characterize diazotrophs able to solubilize phosphates in vitro and (ii evaluate the initial performance of the pineapple cultivars Imperial and Pérola in response to inoculation with selected bacteria in combination with rock phosphate. The experiments were conducted at Universidade Estadual do Norte Fluminense Darcy Ribeiro, in 2009. In the treatments with bacteria the leaf contents of N, P and K were higher than those of the controls, followed by an increase in plant growth. These results indicate that the combined application of diazotrophic phosphate-solubilizing bacteria Burkholderia together with Araxá rock phosphate can be used to improve the initial performance of pineapple slips.

Experimental and in silico investigations of organic phosphates and phosphonates sorption on polymer-ceramic monolithic materials and hydroxyapatite.

Science.gov (United States)

Pietrzyńska, Monika; Zembrzuska, Joanna; Tomczak, Rafał; Mikołajczyk, Jakub; Rusińska-Roszak, Danuta; Voelkel, Adam; Buchwald, Tomasz; Jampílek, Josef; Lukáč, Miloš; Devínsky, Ferdinand

2016-10-10

A method based on experimental and in silico evaluations for investigating interactions of organic phosphates and phosphonates with hydroxyapatite was developed. This quick and easy method is used for determination of differences among organophosphorus compounds of various structures in their mineral binding affinities. Empirical sorption evaluation was carried out using liquid chromatography with tandem mass spectrometry or UV-VIS spectroscopy. Raman spectroscopy was used to confirm sorption of organic phosphates and phosphonates on hydroxyapatite. Polymer-ceramic monolithic material and bulk hydroxyapatite were applied as sorbent materials. Furthermore, a Polymer-ceramic Monolithic In-Needle Extraction device was used to investigate both sorption and desorption steps. Binding energies were computed from the fully optimised structures utilising Density Functional Theory (DFT) at B3LYP/6-31+G(d,p) level. Potential pharmacologic and toxic effects of the tested compounds were estimated by the Prediction of the Activity Spectra of Substances using GeneXplain software. Copyright © 2016 Elsevier B.V. All rights reserved.

How do arbuscular mycorrhizal fungi handle phosphate? New insight into fine-tuning of phosphate metabolism.

Science.gov (United States)

Ezawa, Tatsuhiro; Saito, Katsuharu

2018-04-27

Contents Summary I. Introduction II. Foraging for phosphate III. Fine-tuning of phosphate homeostasis IV. The frontiers: phosphate translocation and export V. Conclusions and outlook Acknowledgements References SUMMARY: Arbuscular mycorrhizal fungi form symbiotic associations with most land plants and deliver mineral nutrients, in particular phosphate, to the host. Therefore, understanding the mechanisms of phosphate acquisition and delivery in the fungi is critical for full appreciation of the mutualism in this association. Here, we provide updates on physical, chemical, and biological strategies of the fungi for phosphate acquisition, including interactions with phosphate-solubilizing bacteria, and those on the regulatory mechanisms of phosphate homeostasis based on resurveys of published genome sequences and a transcriptome with reference to the latest findings in a model fungus. For the mechanisms underlying phosphate translocation and export to the host, which are major research frontiers in this field, not only recent advances but also testable hypotheses are proposed. Lastly, we briefly discuss applicability of the latest tools to gene silencing in the fungi, which will be breakthrough techniques for comprehensive understanding of the molecular basis of fungal phosphate metabolism. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

The Path of Carbon in Photosynthesis. XXI. The Cyclic Regenerationof Carbon Dioxide Acceptor

Energy Technology Data Exchange (ETDEWEB)

Bassham, J.A.; Benson, A.A.; Kay, Lorel D.; Harris, Anne Z.; Wilson, A.T.; Calvin, M.

1953-10-01

Photosynthesizing plants have been exposed to C{sup 14}O{sub 2} for short periods of time (0.4 to 15 sec.) and the products of carbon dioxide reduction analyzed by paper chromatography and radio autography. Methods have been developed for the degradation of ribulose and sedoheptulose. These sugars, obtained as their phosphate esters from the above C{sup 14}O{sub 2} exposures and from other experiments, have been degraded and their distribution of radiocarbon determined. The distribution of radiocarbon in these sugars, and other data, indicate that sedoheptulose phosphate and ribulose diphosphates are formed during photosynthesis from triose and hexose phosphates, the latter being synthesized, in turn, by the reduction of 3-phosphoglyceric acid.

Patterns of binding of aluminum-containing adjuvants to Haemophilus influenzae type b and meningococcal group C conjugate vaccines and components.

Science.gov (United States)

Otto, Robert B D; Burkin, Karena; Amir, Saba Erum; Crane, Dennis T; Bolgiano, Barbara

2015-09-01

The basis of Haemophilus influenzae type b (Hib) and Neisseria meningitidis serogroup C (MenC) glycoconjugates binding to aluminum-containing adjuvants was studied. By measuring the amount of polysaccharide and protein in the non-adsorbed supernatant, the adjuvant, aluminum phosphate, AlPO4, was found to be less efficient than aluminum hydroxide, Al(OH)3 at binding to the conjugates, at concentrations relevant to licensed vaccine formulations and when equimolar. At neutral pH, binding of TT conjugates to AlPO4 was facilitated through the carrier protein, with only weak binding of AlPO4 to CRM197 being observed. There was slightly higher binding of either adjuvant to tetanus toxoid conjugates, than to CRM197 conjugates. This was verified in AlPO4 formulations containing DTwP-Hib, where the adsorption of TT-conjugated Hib was higher than CRM197-conjugated Hib. At neutral pH, the anionic Hib and MenC polysaccharides did not appreciably bind to AlPO4, but did bind to Al(OH)3, due to electrostatic interactions. Phosphate ions reduced the binding of the conjugates to the adjuvants. These patterns of adjuvant adsorption can form the basis for future formulation studies with individual and combination vaccines containing saccharide-protein conjugates. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Formulation of single super phosphate fertilizer from rock phosphate of Hazara, Pakistan

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Matiullah Khan

2012-05-01

Full Text Available Phosphorus deficiency is wide spread in soils of Pakistan. It is imperative to explore the potential and economics of indigenous Hazara rock phosphate for preparation of single super phosphate fertilizer. For the subject study rock phosphate was collected from Hazara area ground at 160 mesh level with 26% total P2O5 content for manual preparation of single super phosphate fertilizer. The rock phosphate was treated with various concentrations of sulfuric acid (98.9%, diluted or pure in the field. The treatments comprised of 20 and 35% pure acid and diluted with acid-water ratios of 1:5, 1:2, 1:1 and 2:1 v/v for acidulation at the rate of 60 liters 100 kg-1 rock phosphate. The amount was prior calculated in the laboratory for complete wetting of rock phosphate. A quantity of 150 kg rock phosphate was taken as treatment. The respective amount of acid was applied with the spray pump of stainless steel or poured with bucket. After proper processing, chemical analysis of the products showed a range of available P2O5 content from 9.56 to 19.24% depending upon the amount of acid and its dilution. The results reveal at that 1:1 dilutions gave the highest P2O5 content (19.24%, lowest free acid (6 % and 32% weight increase. The application of acid beyond or below this combination either pure or diluted gave hygroscopic product and higher free acids. The cost incurred upon the manual processing was almost half the prevailing rates in the market. These results lead to conclude that application of sulfuric acid at the rate of 60 liters 100 kg-1 with the dilution of 50% (v/v can yield better kind of SSP from Hazara rock phosphate at lower prices.

Integrated assessment of the phosphate industry

International Nuclear Information System (INIS)

Ryan, M.T.; Cotter, S.J.

1980-05-01

The phosphate industry in the United States includes three major activities, namely, mining and milling of phosphate rock, phosphate product manufacture, and phosphate product use. Phosphatic materials contain uranium, thorium, and their decay products in greater than background amounts. This assessment of the radiological impacts associated with the redistribution of radioactive components of phosphate materials may provide insight into the effects of uranium extraction from phosphate materials for use in the nuclear fuel cycle

Role of Phosphate Transport System Component PstB1 in Phosphate Internalization by Nostoc punctiforme.

Science.gov (United States)

Hudek, L; Premachandra, D; Webster, W A J; Bräu, L

2016-11-01

In bacteria, limited phosphate availability promotes the synthesis of active uptake systems, such as the Pst phosphate transport system. To understand the mechanisms that facilitate phosphate accumulation in the cyanobacterium Nostoc punctiforme, phosphate transport systems were identified, revealing a redundancy of Pst phosphate uptake systems that exists across three distinct operons. Four separate PstB system components were identified. pstB1 was determined to be a suitable target for creating phenotypic mutations that could result in the accumulation of excessive levels of phosphate through its overexpression or in a reduction of the capacity to accumulate phosphate through its deletion. Using quantitative real-time PCR (qPCR), it was determined that pstB1 mRNA levels increased significantly over 64 h in cells cultured in 0 mM added phosphate and decreased significantly in cells exposed to high (12.8 mM) phosphate concentrations compared to the level in cells cultured under normal (0.8 mM) conditions. Possible compensation for the loss of PstB1 was observed when pstB2, pstB3, and pstB4 mRNA levels increased, particularly in cells starved of phosphate. The overexpression of pstB1 increased phosphate uptake by N. punctiforme and was shown to functionally complement the loss of PstB in E. coli PstB knockout (PstB - ) mutants. The knockout of pstB1 in N. punctiforme did not have a significant effect on cellular phosphate accumulation or growth for the most part, which is attributed to the compensation for the loss of PstB1 by alterations in the pstB2, pstB3, and pstB4 mRNA levels. This study provides novel in vivo evidence that PstB1 plays a functional role in phosphate uptake in N. punctiforme IMPORTANCE: Cyanobacteria have been evolving over 3.5 billion years and have become highly adept at growing under limiting nutrient levels. Phosphate is crucial for the survival and prosperity of all organisms. In bacteria, limited phosphate availability promotes the

A Conserved Two-Component Signal Transduction System Controls the Response to Phosphate Starvation in Bifidobacterium breve UCC2003.

NARCIS (Netherlands)

Alvarez-Martin, P.; Fernandez, M.; O'Connell-Motherway, M.; O'Connell, K.J.; Sauvageot, N.; Fitzgerald, G.F.; Macsharry, J.; Zomer, A.L.; Sinderen, D. van

2012-01-01

This work reports on the identification and molecular characterization of the two-component regulatory system (2CRS) PhoRP, which controls the response to inorganic phosphate (P(i)) starvation in Bifidobacterium breve UCC2003. The response regulator PhoP was shown to bind to the promoter region of

Effects of education on low-phosphate diet and phosphate binder intake to control serum phosphate among maintenance hemodialysis patients: A randomized controlled trial

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Eunsoo Lim

2018-03-01

Full Text Available Background : For phosphate control, patient education is essential due to the limited clearance of phosphate by dialysis. However, well-designed randomized controlled trials about dietary and phosphate binder education have been scarce. Methods : We enrolled maintenance hemodialysis patients and randomized them into an education group (n = 48 or a control group (n = 22. We assessed the patients' drug compliance and their knowledge about the phosphate binder using a questionnaire. Results : The primary goal was to increase the number of patients who reached a calcium-phosphorus product of lower than 55. In the education group, 36 (75.0% patients achieved the primary goal, as compared with 16 (72.7% in the control group (P = 0.430. The education increased the proportion of patients who properly took the phosphate binder (22.9% vs. 3.5%, P = 0.087, but not to statistical significance. Education did not affect the amount of dietary phosphate intake per body weight (education vs. control: -1.18 ± 3.54 vs. -0.88 ± 2.04 mg/kg, P = 0.851. However, the dietary phosphate-to-protein ratio tended to be lower in the education group (-0.64 ± 2.04 vs. 0.65 ± 3.55, P = 0.193. The education on phosphate restriction affected neither the Patient-Generated Subjective Global Assessment score (0.17 ± 4.58 vs. -0.86 ± 3.86, P = 0.363 nor the level of dietary protein intake (-0.03 ± 0.33 vs. -0.09 ± 0.18, P = 0.569. Conclusion : Education did not affect the calcium-phosphate product. Education on the proper timing of phosphate binder intake and the dietary phosphate-to-protein ratio showed marginal efficacy.

Zinc phosphate conversion coatings

Science.gov (United States)

Sugama, Toshifumi

1997-01-01

Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate .alpha.-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal.

Calcium Carbonate Phosphate Binding Ion Exchange Filtration and Accelerated Denitrification Improve Public Health Standards and Combat Eutrophication in Aquatic Ecosystems

OpenAIRE

Yanamadala, Vijay

2005-01-01

Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the gre...

A generalized allosteric mechanism for cis-regulated cyclic nucleotide binding domains.

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Alexandr P Kornev

2008-04-01

Full Text Available Cyclic nucleotides (cAMP and cGMP regulate multiple intracellular processes and are thus of a great general interest for molecular and structural biologists. To study the allosteric mechanism of different cyclic nucleotide binding (CNB domains, we compared cAMP-bound and cAMP-free structures (PKA, Epac, and two ionic channels using a new bioinformatics method: local spatial pattern alignment. Our analysis highlights four major conserved structural motifs: 1 the phosphate binding cassette (PBC, which binds the cAMP ribose-phosphate, 2 the "hinge," a flexible helix, which contacts the PBC, 3 the beta(2,3 loop, which provides precise positioning of an invariant arginine from the PBC, and 4 a conserved structural element consisting of an N-terminal helix, an eight residue loop and the A-helix (N3A-motif. The PBC and the hinge were included in the previously reported allosteric model, whereas the definition of the beta(2,3 loop and the N3A-motif as conserved elements is novel. The N3A-motif is found in all cis-regulated CNB domains, and we present a model for an allosteric mechanism in these domains. Catabolite gene activator protein (CAP represents a trans-regulated CNB domain family: it does not contain the N3A-motif, and its long range allosteric interactions are substantially different from the cis-regulated CNB domains.

Modeling cell membrane transport: interaction of guanidinylated poly(propylene imine) dendrimers with a liposomal membrane consisting of phosphate-based lipids.

Science.gov (United States)

Tsogas, Ioannis; Tsiourvas, Dimitris; Nounesis, George; Paleos, Constantinos M

2006-12-19

Mixed anionic liposomes consisting of dihexadecyl phosphate, phosphatidylcholine, and cholesterol were employed as model systems for assessing the ability of a series of functionalized dendrimers, bearing a varying number of guanidinium groups at their surface, to translocate across the liposomal bilayers. At low guanidinium/phosphate molar ratios or when weakly guanidinylated dendrimeric derivatives were employed, the dendrimeric derivative acted as a kind of "molecular glue" leading to a simple adhesion of the liposomes. Liposomal fusion occurred to a certain extent at high guanidinium/phosphate molar ratios or when highly guanidinylated dendrimeric derivatives were employed. Furthermore, translocation of these dendrimeric derivatives to the liposomal core was observed for low to medium guanidinylation and at low guanidinium/phosphate molar ratios which was, however, enhanced when the lipid bilayer was in its fluid liquid-crystalline phase. Thus, an optimum balance is required between the binding strength of guanidinium with the phosphate groups and the degree of hydrophilicity of the guanidinylated dendrimers for the transport of the latter to the liposomal core to occur.

Study of the nature of the binding of phosphate residues in the phosphorylated form of succinyl-CoA synthetase from pigeon breast muscle

International Nuclear Information System (INIS)

Valiulina, D.S.; Skalbe, T.A.; Matveeva, L.N.

1987-01-01

The hydrolytic stability of the phosphorylated protein was investigated within a wide pH range. It was shown that the bond of the phosphate residue to protein in complex I is hydrolyzed at alkaline pH values (11.0 and 13.0). At acid pH values this bond is 50% hydrolyzed. The bond of the phosphate residue to protein in complex II is hydrolyzed at acid pH values and is stable at alkaline pH values of the medium. The phosphorylation reaction of the enzyme I, both with hydroxylamine and with diisopropyl fluorophosphate, led to 50% dephosphorylation of the protein. An analysis of an alkaline hydrolysate (3 N NaOH, 3 h, 100 0 C) of the radioactive phosphorylated enzyme II by ion exchange chromatography showed that the radioactive label of the protein is distributed in the fractions of 1-N- and 3-N-phosphohistidine, as well as 1,3-N-diphosphohistidine. The data obtained suggested that phosphate in the phosphorylated enzyme I is bound to protein, with the formation of acyl phosphate and phosphoester bonds. Phosphate in the phosphorylated enzyme II is bound to protein with the formation of a phosphoamide bond

Study of the nature of the binding of phosphate residues in the phosphorylated form of succinyl-CoA synthetase from pigeon breast muscle

Energy Technology Data Exchange (ETDEWEB)

Valiulina, D.S.; Skalbe, T.A.; Matveeva, L.N.

1987-01-10

The hydrolytic stability of the phosphorylated protein was investigated within a wide pH range. It was shown that the bond of the phosphate residue to protein in complex I is hydrolyzed at alkaline pH values (11.0 and 13.0). At acid pH values this bond is 50% hydrolyzed. The bond of the phosphate residue to protein in complex II is hydrolyzed at acid pH values and is stable at alkaline pH values of the medium. The phosphorylation reaction of the enzyme I, both with hydroxylamine and with diisopropyl fluorophosphate, led to 50% dephosphorylation of the protein. An analysis of an alkaline hydrolysate (3 N NaOH, 3 h, 100/sup 0/C) of the radioactive phosphorylated enzyme II by ion exchange chromatography showed that the radioactive label of the protein is distributed in the fractions of 1-N- and 3-N-phosphohistidine, as well as 1,3-N-diphosphohistidine. The data obtained suggested that phosphate in the phosphorylated enzyme I is bound to protein, with the formation of acyl phosphate and phosphoester bonds. Phosphate in the phosphorylated enzyme II is bound to protein with the formation of a phosphoamide bond.

Hemodialysis for near-fatal sodium phosphate toxicity in a child receiving sodium phosphate enemas.

Science.gov (United States)

Becknell, Brian; Smoyer, William E; O'Brien, Nicole F

2014-11-01

This study aimed to demonstrate the importance of considering hemodialysis as a treatment option in the management of sodium phosphate toxicity. This is a case report of a 4-year-old who presented to the emergency department with shock, decreased mental status, seizures, and tetany due to sodium phosphate toxicity from sodium phosphate enemas. Traditional management of hyperphosphatemia with aggressive hydration and diuretics was insufficient to reverse the hemodynamic and neurological abnormalities in this child. This is the first report of the use of hemodialysis in a child without preexisting renal failure for the successful management of near-fatal sodium phosphate toxicity. Hemodialysis can safely be used as an adjunctive therapy in sodium phosphate toxicity to rapidly reduce serum phosphate levels and increase serum calcium levels in children not responding to conventional management.

Formation and characterization of iron-binding phosphorylated human-like collagen as a potential iron supplement

Energy Technology Data Exchange (ETDEWEB)

Deng, Jianjun; Chen, Fei; Fan, Daidi, E-mail: fandaidi@nwu.edu.cn; Zhu, Chenhui; Ma, Xiaoxuan; Xue, Wenjiao

2013-10-01

Iron incorporated into food can induce precipitation and unwanted interaction with other components in food. Iron-binding proteins represent a possibility to avoid these problems and other side effects, as the iron is protected. However, there are several technical problems associated with protein–iron complex formation. In this paper, the iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared under physiological conditions through phosphorylated modification. One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. Spectroscopy analysis, differential scanning calorimetry (DSC) and equilibrium dialysis techniques were employed to investigate the characteristics of the Fe-G6P-HLC. The binding sites (n{sub b}) and apparent association constant (K{sub app}) between iron and phosphorylated HLC were measured at n{sub b} = 23.7 and log K{sub app} = 4.57, respectively. The amount of iron (Fe{sup 2+} sulfate) binding to phosphorylated HLC was found to be a function of pH and phosphate content. In addition, the solubility and thermal stability of HLC were not significantly affected. The results should facilitate the utilization of HLC as a bioactive iron supplement in the food and medical industry and provide an important theoretical evidence for the application of HLC chelates. - Highlights: • The iron-binding phosphorylated human-like collagen (Fe-G6P-HLC) was prepared. • One molecule of Fe-G6P-HLC possesses about 24 atoms of Fe. • The binding properties could be modulated through alterations in pH and phosphate content presented in HLC. • A novel strategy for preparing iron-binding proteins was provided.

Phosphate transporter mediated lipid accumulation in Saccharomyces cerevisiae under phosphate starvation conditions.

Science.gov (United States)

James, Antoni W; Nachiappan, Vasanthi

2014-01-01

In the current study, when phosphate transporters pho88 and pho86 were knocked out they resulted in significant accumulation (84% and 43%) of triacylglycerol (TAG) during phosphate starvation. However in the presence of phosphate, TAG accumulation was only around 45% in both pho88 and pho86 mutant cells. These observations were confirmed by radio-labeling, fluorescent microscope and RT-PCR studies. The TAG synthesizing genes encoding for acyltransferases namely LRO1 and DGA1 were up regulated. This is the first report for accumulation of TAG in pho88Δ and pho86Δ cells under phosphate starvation conditions. Copyright © 2013. Published by Elsevier Ltd.

Kinetics of beta2-microglobulin and phosphate during hemodialysis: effects of treatment frequency and duration.

Science.gov (United States)

Leypoldt, John K

2005-01-01

whose removal during hemodialysis is governed predominantly by clearance at the dialyzer. In contrast, phosphate removal is limited primarily by its sequestration in the intracellular compartment (and possibly other compartments), not by its clearance at the dialyzer. The kinetics of phosphate may therefore be representative of uremic toxins whose removal is limited by sequestration into compartments or by protein binding. Enhanced removal of both of these uremic toxins using a given therapy will require treatments of increased frequency and longer duration.

A lipid binding domain in sphingosine kinase 2

International Nuclear Information System (INIS)

Don, Anthony S.; Rosen, Hugh

2009-01-01

The lipid second messenger sphingosine 1-phosphate (S1P) is a critical mediator of cellular proliferation and survival signals, and is essential for vasculogenesis and neurogenesis. S1P formation is catalysed by sphingosine kinases 1 and 2 (Sphk1 and Sphk2). We have found that the endogenous glycolipid sulfatide (3-O-sulfogalactosylceramide) binds to and inhibits the activity of Sphk2 and the closely related ceramide kinase (Cerk), but not Sphk1. Using sulfatide as a probe, we mapped the lipid binding domain to the N-terminus of Sphk2 (residues 1-175), a region of sequence that is absent in Sphk1, but aligns with a pleckstrin homology domain in Cerk. Accordingly, Sphk2 bound to phosphatidylinositol monophosphates but not to abundant cellular phospholipids. Deleting the N-terminal domain reduced Sphk2 membrane localisation in cells. We have therefore identified a lipid binding domain in Sphk2 that is important for the enzyme's sub-cellular localisation.

21 CFR 137.175 - Phosphated flour.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Phosphated flour. 137.175 Section 137.175 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Related Products § 137.175 Phosphated flour. Phosphated flour, phosphated white flour, and phosphated...

What is the role of the second "structural" NADP+-binding site in human glucose 6-phosphate dehydrogenase?

Science.gov (United States)

Wang, Xiao-Tao; Chan, Ting Fai; Lam, Veronica M S; Engel, Paul C

2008-08-01

Human glucose 6-phosphate dehydrogenase, purified after overexpression in E. coli, was shown to contain one molecule/subunit of acid-extractable "structural" NADP+ and no NADPH. This tightly bound NADP+ was reduced by G6P, presumably following migration to the catalytic site. Gel-filtration yielded apoenzyme, devoid of bound NADP+ but, surprisingly, still fully active. Mr of the main component of "stripped" enzyme by gel filtration was approximately 100,000, suggesting a dimeric apoenzyme (subunit Mr = 59,000). Holoenzyme also contained tetramer molecules and, at high protein concentration, a dynamic equilibrium gave an apparent intermediate Mr of 150 kDa. Fluorescence titration of the stripped enzyme gave the K d for structural NADP+ as 37 nM, 200-fold lower than for "catalytic" NADP+. Structural NADP+ quenches 91% of protein fluorescence. At 37 degrees C, stripped enzyme, much less stable than holoenzyme, inactivated irreversibly within 2 d. Inactivation at 4 degrees C was partially reversed at room temperature, especially with added NADP+. Apoenzyme was immediately active, without any visible lag, in rapid-reaction studies. Human G6PD thus forms active dimer without structural NADP+. Apparently, the true role of the second, tightly bound NADP+ is to secure long-term stability. This fits the clinical pattern, G6PD deficiency affecting the long-lived non-nucleate erythrocyte. The Kd values for two class I mutants, G488S and G488V, were 273 nM and 480 nM, respectively (seven- and 13-fold elevated), matching the structural prediction of weakened structural NADP+ binding, which would explain decreased stability and consequent disease. Preparation of native apoenzyme and measurement of Kd constant for structural NADP+ will now allow quantitative assessment of this defect in clinical G6PD mutations.

Mutual effects of copper and phosphate on their interaction with γ-Al2O3: combined batch macroscopic experiments with DFT calculations.

Science.gov (United States)

Ren, Xuemei; Yang, Shitong; Tan, Xiaoli; Chen, Changlun; Sheng, Guodong; Wang, Xiangke

2012-10-30

The mutual effects of Cu(II) and phosphate on their interaction with γ-Al(2)O(3) are investigated by using batch experiments combined with density functional theory (DFT) calculations. The results of batch experiments show that coexisting phosphate promotes the retention of Cu(II) on γ-Al(2)O(3), whereas phosphate retention is not affected by coexisting Cu(II) at low initial phosphate concentrations (≤ 3.6 mg P/L). Cu-phosphate aqueous complexes control Cu(II) retention through the formation of type B ternary surface complexes (where phosphate bridges γ-Al(2)O(3) and Cu(II)) at pH 5.5. This deduction is further supported by the results of DFT calculations. More specifically, the DFT calculation results indicate that the type B ternary surface complexes prefer to form outer-sphere or monodentate inner-sphere binding mode under our experimental conditions. The enhancement of phosphate retention on γ-Al(2)O(3) in the presence of Cu(II) at high initial phosphate concentrations (>3.6 mg P/L) may be attributed to the formation of 1:2 Cu(II)-phosphate species and/or surface precipitates. Understanding the mutual effects of phosphate and Cu(II) on their mobility and transport in mineral/water environments is more realistic to design effective remediation strategies for reducing their negative impacts on aquatic/terrestrial environments. Copyright © 2012 Elsevier B.V. All rights reserved.

Preferable removal of phosphate from water using hydrous zirconium oxide-based nanocomposite of high stability

International Nuclear Information System (INIS)

Chen, Liang; Zhao, Xin; Pan, Bingcai; Zhang, Weixian; Hua, Ming; Lv, Lu; Zhang, Weiming

2015-01-01

Highlights: • The nanocomposite HZO-201 was stable under varying solution chemistry. • HZO-201 exhibited preferable phosphate removal over other ubiquitous anions. • Selective sorption mechanism was probed and discussed. • HZO-201 could be regenerated for cyclic use with constant efficiency. - Abstract: In this study, we employed a new nanocomposite adsorbent HZO-201, which featured high stability under varying solution chemistry, for preferable removal of phosphate from synthetic solution and a real effluent. An anion exchange resin (D-201) was employed as the host of HZO-201, where nano-hydrous zirconium oxide (HZO) was encapsulated as the active species. D-201 binds phosphate through nonspecific electrostatic affinity, whereas the loaded HZO nanoparticles capture phosphate through formation of the inner-sphere complexes. Quantitative contribution of both species to phosphate adsorption was predicted based on the double-Langmuir model. Preferable removal of phosphate by HZO-201 was observed in the presence of the competing anions at higher levels (Cl − , NO 3 − , SO 4 2− , HCO 3 − ). Fixed-bed adsorption indicated that the effective volume capacity of a synthetic water (2.0 mg P-PO 4 3− /L) by using HZO-201 was ∼1600 BV in the first run (<0.5 mg P-PO 4 3− /L), comparable to Fe(III)-based nanocomposite HFO-201 (∼1500 BV) and much larger than D-201 (<250 BV). The exhausted HZO-201 can be in situ regenerated by using a binary NaOH–NaCl solution for cyclic runs, whether fed with the synthetic solution or real effluent. In general, HZO-201 is a promising alternative to Fe(III)-based adsorbents for trace phosphate removal from effluent particularly at acidic pH

MTH1 and RGT1 demonstrate combined haploinsufficiency in regulation of the hexose transporter genes in Saccharomyces cerevisiae

Directory of Open Access Journals (Sweden)

Dietzel Kevin L

2012-12-01

Full Text Available Abstract Background The SNF3 gene in the yeast Saccharomyces cerevisiae encodes a low glucose sensor that regulates expression of an important subset of the hexose transporter (HXT superfamily. Null mutations of snf3 result in a defect in growth on low glucose concentrations due to the inability to relieve repression of a subset of the HXT genes. The snf3 null mutation phenotype is suppressed by the loss of either one of the downstream co-repressor proteins Rgt1p or Mth1p. The relief of repression allows expression of HXT transporter proteins, the resumption of glucose uptake and therefore of growth in the absence of a functional Snf3 sensor. Results Strains heterozygous for both the RGT1 and MTH1 genes (RGT1/rgt1Δ MTH1/mth1Δ snf3Δ/snf3Δ but homozygous for the snf3∆ were found to grow on low glucose. Since null alleles in the heterozygous state lead to suppression, MTH1 and RGT1 display the phenomenon of combined haploinsufficiency. This observed haploinsufficiency is consistent with the finding of repressor titration as a mechanism of suppression of snf3. Mutants of the STD1 homolog of MTH1 did not display haploinsufficiency singly or in combination with mutations in RGT1. HXT gene reporter fusion assays indicated that the presence of heterozygosity at the MTH1 and RGT1 alleles leads to increased expression of the HXT2 gene. Deletion of the HXT2 gene in a heterozygous diploid, RGT1/rgt1Δ MTH1/mth1Δ snf3Δ/snf3Δ hxt2Δ/hxt2Δ, prevented the suppression of snf3Δ. Conclusions These findings support the model of relief of repression as the mechanism of restoration of growth on low glucose concentrations in the absence of functional Snf3p. Further, the observation that HXT2 is the gene responsible for restoration of growth under these conditions suggests that the numbers of repressor binding domains found in the regulatory regions of members of the HXT family may have biological relevance and enable differential regulation.

Remote Sensing and Geographic Information Systems as Decision Support Tools for Malaria Control in the Republic of Korea

Science.gov (United States)

2001-05-30

remote sensing and GIS techniques to monitor vectors and vector-borne disease in Mexico, Belize and, more recently, Peru (Roberts et al. 1999...parasite is severe hemolytic anemia in persons who are deficient in glucose-6- phosphate dehydrogenase (G-6-PD). Primaquine is the only drug currently...the denaturation of hemoglobin, resulting in hemoglobinuria, kidney damage and anemia . Erythrocytes are protected from oxidation by the hexose

Effects of Microbial and Phosphate Amendments on the Bioavailability of Lead (Pb) in Shooting Range Soil

Energy Technology Data Exchange (ETDEWEB)

Brigmon, Robin; Wilson, Christina; Knox, Anna; Seaman, John; Smith, Garriet

2005-06-16

Heavy metals including lead (Pb) are released continually into the environment as a result of industrial, recreational, and military activities. Lead ranked number two on the CERCLA Priority List of Hazardous Substances and was identified as a major hazardous chemical found on 47% of USEPA's National Priorities List sites (Hettiarachchi and Pierzynski 2004). In-situ remediation of lead (Pb) contaminated soils may be accomplished by changing the soil chemistry and structure with the application of microbial and phosphate amendments. Soil contaminated with lead bullets was collected from the surface of the berm at Savannah River Site (SRS) Small Arms Training Academy (SATA) in Aiken, SC. While uncontaminated soils typically have Pb levels ranging from 2 to 200 mg/kg (Berti et al. 1998), previous analysis show Pb levels of the SATA berm to reach 8,673 mg/kg. Biosurfactants are surface-active compounds naturally produced by soil bacteria that can bind metals. Biosurfactants have a wide variety of chemical structures that reduce interfacial surface tensions (Jennings and Tanner 2000) and have demonstrated efficient metal complexion (Lin 1996). Biosurfactants also have the potential to change the availability of natural organic matter (Strong-Gunderson 1995). Two types of bacteria, Alcaligenes piechaudii and Pseudomonas putida, were employed as amendments based on their ability to produce biosurfactants and survive in metal-contaminated soils. Apatites (calcium phosphate compounds) are important in the formation of Pb phosphates. Pb phosphates form rapidly when phosphate is available and are the most stable environmental form of lead in soil (Ruby et al.1998). Pyromorphites in particular remain insoluble under a wide range of environmental conditions (Zhang et al. 1998). The three apatites evaluated in the current study were North Carolina apatite (NCA), Florida apatite (FA), and biological apatite (BA). BA is ground fish bone that has few impurities such as As, Cr

The treatment of Plasmodium falciparum-infected erythrocytes with chloroquine leads to accumulation of ferriprotoporphyrin IX bound to particular parasite proteins and to the inhibition of the parasite's 6-phosphogluconate dehydrogenase

Directory of Open Access Journals (Sweden)

Famin O.

2003-03-01

Full Text Available Ferriprotoporphyrin IX (FPIX is a potentially toxic product of hemoglobin digestion by intra-erythrocytic malaria parasites. It is detoxified by biomineralization or through degradation by glutathione. Both processes are inhibited by the antimalarial drug chloroquine, leading to the accumulation of FPIX in the membranes of the infected cell and their consequent permeabilization. It is shown here that treatment of Plasmodium falciparum-infected erythrocytes with chloroquine also leads to the binding of FPIX to a subset of parasite proteins. Parasite enzymes such as aldolase, pyrimidine nucleoside monophosphate kinase and pyrimidine 5'- nucleotidase were inhibited by FPIX in vitro, but only the activity of 6-phosphogluconate dehydrogenase was reduced significantly in cells after drug treatment. Additional proteins were extracted from parasite cytosol by their ability to bind FPIX. Sequencing of these proteins identified heat shock proteins 90 and 70, enolase, elongation factor 1-α, phoshoglycerate kinase, glyceraldehyde 3- phosphate dehydrogenase, L-lactate dehydrogenase and gametocytogenesis onset-specific protein. The possible involvement of these proteins in the antimalarial mode of action of chloroquine is discussed. It is concluded that drug-induced binding of FPIX to parasite glycolytic enzymes could underlie the demonstrable inhibition of glycolysis by chloroquine. The inhibition of 6- phosphogluconate dehydrogenase could explain the reduction of the activity of the hexose monophosphate shunt by the drug. Inhibition of both processes is deleterious to parasite survival. Binding of FPIX to other proteins is probably inconsequential to the rapid killing of the parasite by chloroquine.

Genomes of rumen bacteria encode atypical pathways for fermenting hexoses to short-chain fatty acids

KAUST Repository

Hackmann, Timothy J.

2017-09-11

Bacteria have been thought to follow only a few well-recognized biochemical pathways when fermenting glucose or other hexoses. These pathways have been chiseled in the stone of textbooks for decades, with most sources rendering them as they appear in the classic 1986 text by Gottschalk. Still, it is unclear how broadly these pathways apply, given that they were established and delineated biochemically with only a few model organisms. Here we show that well-recognized pathways often cannot explain fermentation products formed by bacteria. In the most extensive analysis of its kind, we reconstructed pathways for glucose fermentation from genomes of 48 species and subspecies of bacteria from one environment (the rumen). In total, 44% of these bacteria had atypical pathways, including several that are completely unprecedented for bacteria or any organism. In detail, 8% of bacteria had an atypical pathway for acetate formation; 21% for propionate or succinate formation; 6% for butyrate formation; and 33% had an atypical or incomplete Embden-Meyerhof-Parnas pathway. This study shows that reconstruction of metabolic pathways-a common goal of omics studies-could be incorrect if well-recognized pathways are used for reference. Further, it calls for renewed efforts to delineate fermentation pathways biochemically. This article is protected by copyright. All rights reserved.

Different effects of copper (II), cadmium (II) and phosphate on the sorption of phenanthrene on the biomass of cyanobacteria.

Science.gov (United States)

Tao, Yuqiang; Li, Wei; Xue, Bin; Zhong, Jicheng; Yao, Shuchun; Wu, Qinglong

2013-10-15

Due to the large surface area and high organic carbon content of cyanobacteria, organic contaminants can be readily sorbed on cyanobacteria during algal blooms, and then be transferred to the food web. This process is likely to be affected by the coexisting metals and nutrients, however, the possible impacts remain unclear. Effects of Cu(2+), Cd(2+), and phosphate on the sorption of phenanthrene on cyanobacterial biomass collected from an algal bloom were therefore studied. Continuous decrease in phenanthrene sorption was observed in the presence of low concentrations of Cu(2+), and Cd(2+) (phosphate concentration. Phosphate blocked the binding sites, modified the cell morphology, and increased the negative charge as well as the hydrophilicity of the cyanobacterial surface, thereby suppressing phenanthrene sorption. This study indicates that sorption of aromatic organic compounds by cyanobacteria could be significantly alerted by concentrations and properties of the coexisting transition metals and phosphates, which may subsequently affect their transfer to the food web in eutrophic waters. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Radioactivity of phosphate ores from Karatas-Mazidag phosphate deposit of Turkey

International Nuclear Information System (INIS)

Akyuez, T.; Varinlioglu, A.; Kose, A.; Akyuez, S.

2000-01-01

The specific activities of 238 U, 226 Ra, 232 Th and 40 K in the composite samples of phosphate ores of type I (grey-coloured ore, with high P 2 O 5 (21-35%) and low calcite content) and of type II (grey coloured calcite ore, with low P 2 O 5 content (5-17%)) of Karatas-Mazidag phosphate deposit, Turkey, have been determined by gamma spectrometry together with phosphatic animal feed ingredients. The concentrations of 238 U, 226 Ra, 232 Th and 40 K were found to be up to 557, 625, 26 and 297 Bq x kg -1 , respectively. Radium equivalent activities of samples were calculated and compared with those given in the literature. Uranium concentration of the individual phosphate samples, from which composite samples of ores of type I and II have been prepared, were found to show and increasing trend with increasing P 2 O 5 and F concentrations. (author)

Phosphate application to firing range soils for Pb immobilization: The unclear role of phosphate

International Nuclear Information System (INIS)

Chrysochoou, Maria; Dermatas, Dimitris; Grubb, Dennis G.

2007-01-01

Phosphate treatment has emerged as a widely accepted approach to immobilize Pb in contaminated soils and waste media, relying on the formation of the highly insoluble mineral pyromorphite as solubility-controlling phase for Pb. As such, phosphate treatment has been proposed as a Best Management Practice (BMP) for firing ranges where Pb occurs in its metallic forms and several other phases (carbonates, oxides). While pyromorphite thermodynamically has the potential to control Pb solubility at low levels, its formation is kinetically controlled by pH, the solubility of the phosphate source, and the solubility of Pb species. Treatability studies have shown that excess quantities of soluble and acidic phosphate sources, such as phosphoric acid, are necessary for successful in situ treatment. Even under these conditions, Extended X-ray Absorption Fine Structure (EXAFS), the only reliable method to identify and quantify Pb speciation, showed that Pb conversion to pyromorphite in in situ treated soils was less than 45% after 32 months. Furthermore, the use of lime (CaO) to restore soil pH in acidified soil treatments inhibited further conversion. Additionally, phosphate treatment is known to reduce bioavailability through pyromorphite formation in the intestinal tract, and the phytoaccumulation of Pb; both desirable effects for Pb-impacted areas. Given the costs of phosphate treatment, the use of biogenic phosphate sources, such as bone meal, may be a more environmentally sustainable approach toward this end. In the many studies focusing on phosphate treatment, the attendant P leaching and eutrophication have been largely overlooked, along with other issues such as the enhanced leaching of oxyanionic contaminants, such as Se, As and W. The success and sustainability of applying phosphate as a BMP in firing range soils therefore remain questionable

Plasma levels of sphingosine-1-phosphate and apolipoprotein M in patients with monogenic disorders of HDL metabolism

NARCIS (Netherlands)

Karuna, Ratna; Park, Rebekka; Othman, Alaa; Holleboom, Adriaan G.; Motazacker, Mohammad Mahdi; Sutter, Iryna; Kuivenhoven, Jan Albert; Rohrer, Lucia; Matile, Hugues; Hornemann, Thorsten; Stoffel, Markus; Rentsch, Katharina M.; von Eckardstein, Arnold

2011-01-01

Apolipoprotein M (apoM) has been identified as a specific sphingosine-1-phosphate (S1P) binding protein of HDL. To investigate the in vivo effects of disturbed apoM or HDL metabolism we quantified S1P and apoM in plasmas of wild-type, apoM-knock-out, and apoM transgenic mice as well as 50 patients

Method of stripping plutonium from tributyl phosphate solution which contains dibutyl phosphate-plutonium stable complexes

International Nuclear Information System (INIS)

Ochsenfeld, W.; Schmieder, H.

1976-01-01

Fast breeder fuel elements which have been highly burnt-up are reprocessed by extracting uranium and plutonium into an organic solution containing tributyl phosphate. The tributyl phosphate degenerates at least partially into dibutyl phosphate and monobutyl phosphate, which form stable complexes with tetravalent plutonium in the organic solution. This tetravalent plutonium is released from its complexed state and stripped into aqueous phase by contacting the organic solution with an aqueous phase containing tetravalent uranium. 6 claims, 1 drawing figure

Dithieno[3,2-a:2',3'-c]phenazine-based Chemical Probe for Anions: A Spectroscopic Study of Binding

KAUST Repository

El-Assaad, Tarek H.; Shiring, Stephen B.; Getmanenko, Yulia A.; Hallal, Kassem M.; Bredas, Jean-Luc; Marder, Seth R; Al-Sayah, Mohammad H.; Kaafarani, Bilal R

2015-01-01

of various anions were examined using UV-vis absorption spectroscopy, fluorescence and 1H NMR titration experiments. Strong binding of 1 to carboxylate, cyanide, fluoride and dihydrogen phosphate anions results in an increase in quantum yield for emission

Performance of pineapple slips inoculated with diazotrophic phosphate-solubilizing bacteria and rock phosphate

OpenAIRE

Lílian Estrela Borges Baldotto; Marihus Altoé Baldotto; Fábio Lopes Olivares; Adriane Nunes de Souza

2014-01-01

Besides fixing N2, some diazotrophic bacteria or diazotrophs, also synthesize organic acids and are able to solubilize rock phosphates, increasing the availability of P for plants. The application of these bacteria to pineapple leaf axils in combination with rock phosphate could increase N and P availability for the crop, due to the bacterial activity of biological nitrogen fixation and phosphate solubilization. The objectives of this study were: (i) to select and characterize diazotrophs abl...

Uranium-phosphate relationship in phosphated chalks of the Mons and Picardie Bassins

Energy Technology Data Exchange (ETDEWEB)

Quinif, Y; Charlet, J M; Dupuis, C; Robaszynski, F [Faculte Polytechnique de Mons (Belgium)

1981-11-30

The lithological and geochemical conditions relative to the ''Senonian'' phosphatic chalks are relatively simple in the Basins of Mons (Belgium) and of Picardy (France). Their characteristics permit us to study chiefly the uranium-phosphate relation. It appears a very good linear correlation between the phosphate and the uranium. The coefficient U/P/sub 2/O/sub 5/ remains a constant from the bottom to the top of the same section, but changes in space for synchronic formations (lateral variation of geochemical facies) and in time for two separated basins.

Uranium abundance in some sudanese phosphate ores

International Nuclear Information System (INIS)

Adam, A.A.; Eltayeb, M.A.H.

2009-01-01

This work was carried out mainly to analysis of some Sudanese phosphate ores, for their uranium abundance and total phosphorus content measured as P 2 O 5 %. For this purpose, 30 samples of two types of phosphate ore from Eastern Nuba Mountains, in Sudan namely, Kurun and Uro areas were examined. In addition, the relationship between uranium and major, and trace elements were obtained, also, the natural radioactivity of the phosphate samples was measured, in order to characterize and differentiate between the two types of phosphate ores. The uranium abundance in Uro phosphate with 20.3% P 2 O 5 is five time higher than in Kurun phosphate with 26.7% P 2 O 5 . The average of uranium content was found to be 56.6 and 310 mg/kg for Kurun and Uro phosphate ore, respectively. The main elements in Kurun and Uro phosphate ore are silicon, aluminum, and phosphorus, while the most abundant trace elements in these two ores are titanium, strontium and barium. Pearson correlation coefficient revealed that uranium in Kurun phosphate shows strong positive correlation with P 2 O 5 , and its distribution is essentially controlled by the variations of P2O5 concentration, whereas uranium in Uro phosphate shows strong positive correlation with strontium, and its distribution is controlled by the variations of Sr concentration. Uranium behaves in different ways in Kurun phosphate and in Uro phosphate. Uro phosphate shows higher concentrations of all the estimated radionuclides than Kurun phosphate. According to the obtained results, it can be concluded that Uro phosphate is consider as secondary uranium source, and is more suitable for uranium recovery, because it has high uranium abundance and low P 2 O 5 %, than Kurun phosphate. (authors) [es

Uranium from phosphate ores

International Nuclear Information System (INIS)

Hurst, F.J.

1983-01-01

The following topics are described briefly: the way phosphate fertilizers are made; how uranium is recovered in the phosphate industry; and how to detect covert uranium recovery operations in a phsophate plant

Electrochemical Reduction of Zinc Phosphate

International Nuclear Information System (INIS)

Kim, Chang Hwan; Lee, Jung Hyun; Shin, Woon Sup

2010-01-01

We demonstrated first that the electrochemical reduction of zinc phosphate in neutral phosphate buffer is possible and potentially applicable to bio-compatible rechargeable battery. The actual redox component is Zn(s)/Zn phosphate(s) and the future research about the control of crystal formation for the better cyclability is required. In lead-acid battery, the electrochemical redox reaction of Pb (s) /PbSO 4(s) is used by reducing Pb(II) and oxidizing Pb(0) in sulfate rich solution. Since both reduced form and oxidized form are insoluble, they cannot diffuse to the opposite electrodes and react. It is a very common strategy to make a stable battery electrode that a metal element is reduced and oxidized in solution containing an abundance of anion readily precipitating with the metal ion. For the application of this strategy to construction of rechargeable battery using bio-compatible electrode materials and electrolytes, the use of phosphate ion can be considered as anion readily precipitating with metal ions. If phosphate buffer with neutral pH is used as electrolyte, the better bio-compatibility will be achieved than most of rechargeable battery using strong acid, strong base or organic solvent as electrolyte solution. There are many metal ions readily precipitating with phos-phate ion, and zinc is one of them

A novel-type phosphatidylinositol phosphate-interactive, Ca-binding protein PCaP1 in Arabidopsis thaliana: stable association with plasma membrane and partial involvement in stomata closure.

Science.gov (United States)

Nagata, Chisako; Miwa, Chika; Tanaka, Natsuki; Kato, Mariko; Suito, Momoe; Tsuchihira, Ayako; Sato, Yori; Segami, Shoji; Maeshima, Masayoshi

2016-05-01

The Ca(2+)-binding protein-1 (PCaP1) of Arabidopsis thaliana is a new type protein that binds to phosphatidylinositol phosphates and Ca(2+)-calmodulin complex as well as free Ca(2+). Although biochemical properties, such as binding to ligands and N-myristoylation, have been revealed, the intracellular localization, tissue and cell specificity, integrity of membrane association and physiological roles of PCaP1 are unknown. We investigated the tissue and intracellular distribution of PCaP1 by using transgenic lines expressing PCaP1 linked with a green fluorescence protein (GFP) at the carboxyl terminus of PCaP1. GFP fluorescence was obviously detected in most tissues including root, stem, leaf and flower. In these tissues, PCaP1-GFP signal was observed predominantly in the plasma membrane even under physiological stress conditions but not in other organelles. The fluorescence was detected in the cytosol when the 25-residue N-terminal sequence was deleted from PCaP1 indicating essential contribution of N-myristoylation to the plasma membrane anchoring. Fluorescence intensity of PCaP1-GFP in roots was slightly decreased in seedlings grown in medium supplemented with high concentrations of iron for 1 week and increased in those grown with copper. In stomatal guard cells, PCaP1-GFP was strictly, specifically localized to the plasma membrane at the epidermal-cell side but not at the pore side. A T-DNA insertion mutant line of PCaP1 did not show marked phenotype in a life cycle except for well growth under high CO2 conditions. However, stomata of the mutant line did not close entirely even in high osmolarity, which usually induces stomata closure. These results suggest that PCaP1 is involved in the stomatal movement, especially closure process, in leaves and response to excessive copper in root and leaf as a mineral nutrient as a physiological role.

Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

Energy Technology Data Exchange (ETDEWEB)

Trofimov, A. A.; Polyakov, K. M., E-mail: kostya@eimb.relarn.ru [Russian Academy of Sciences, Engelhardt Institute of Molecular Biology (Russian Federation); Boiko, K. M.; Filimonenkov, A. A. [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Dorovatovskii, P. V. [Kurchatov Center for Synchrotron Radiation and Nanotechnology (Russian Federation); Tikhonova, T. V.; Popov, V. O. [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Koval' chuk, M. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2010-01-15

Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine{sub c}oordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

Structure of octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens in a complex with phosphate

International Nuclear Information System (INIS)

Trofimov, A. A.; Polyakov, K. M.; Boiko, K. M.; Filimonenkov, A. A.; Dorovatovskii, P. V.; Tikhonova, T. V.; Popov, V. O.; Koval'chuk, M. V.

2010-01-01

Octaheme cytochrome c nitrite reductase from Thioalkalivibrio nitratireducens (TvNiR) catalyzes the reduction of nitrite and hydroxylamine to ammonia. The structures of the free enzyme and of the enzyme in complexes with the substrate (nitrite ion) and the inhibitor (azide ion) have been solved previously. In this study we report the structures of the oxidized complex of TvNiR with phosphate and of this complex reduced by europium(II) chloride (1.8- and 2.0-A resolution, the R factors are 15.9 and 16.7%, respectively) and the structure of the enzyme in the complex with cyanide (1.76-A resolution, the R factor is 16.5%), which was prepared by soaking a crystal of the oxidized phosphate complex of TvNiR. In the active site of the enzyme, the phosphate ion binds to the iron ion of the catalytic heme and to the side chains of the catalytic residues Arg131, Tyr303, and His361. The cyanide ion is coordinated to the heme-iron ion and is hydrogen bonded to the residue His361. In the structure of reduced TvNiR, the phosphate ion is bound in the same manner as in the structure of oxidized TvNiR, and the nine c oordinated europium ion is located on the surface of one of the crystallographically independent monomers of the enzyme.

Fermentation of hexoses and pentoses from hydrolyzed soybean hull into ethanol and xylitol by Candida guilliermondii BL 13

Directory of Open Access Journals (Sweden)

F. da Cunha-Pereira

Full Text Available Abstract This work investigated the ability of a recently isolated strain of Candida guilliermondii to convert hexoses and pentoses obtained from acid-enzymatic soybean hull hydrolysates into ethanol and, in smaller amounts, into xylitol. Operational conditions and media formulation were optimized concerning ethanol production using experimental designs (Plackett-Burman and Central Composite Design. Results showed that C. guilliermondii BL 13 was capable of growing in non-supplemented, non-detoxified biomass hydrolysates, and the best culture conditions were determined to be 28 °C, pH 5.0, and 109 CFU mL-1 of inoculum size. Ethanol productivity reached 1.4 g L-1 h-1, and maximal yields of 0.41 g g-1 were obtained, representing 80.4 % of the expected theoretical yields, whereas small amounts of xylitol were also produced. These results suggest that C. guilliermondii BL13 is a potentially useful yeast strain to be applied in second-generation ethanol production from lignocellulosic biomass based on its natural capacity to metabolize C-5 and C-6 sugars.

Radiological impact of natural radioactivity in Egyptian phosphate rocks, phosphogypsum and phosphate fertilizers

International Nuclear Information System (INIS)

El-Bahi, S.M.; Sroor, A.; Mohamed, Gehan Y.; El-Gendy, N.S.

2017-01-01

In this study, the activity concentrations of the natural radionuclides in phosphate rocks and its products were measured using a high- purity germanium detector (HPGe). The obtained activity results show remarkable wide variation in the radioactive contents for the different phosphate samples. The average activity concentration of "2"3"5U, "2"3"8U, "2"2"6Ra, "2"3"2Th and "4"0K was found as (45, 1031, 786, 85 and 765 Bq/kg) for phosphate rocks, (28, 1234, 457, 123 and 819 Bq/kg) for phosphate fertilizers, (47, 663, 550, 79 and 870 Bq/kg) for phosphogypsum and (25, 543, 409, 54 and 897 Bq/kg) for single super phosphate respectively. Based on the measured activities, the radiological parameters (activity concentration index, absorbed gamma dose rate in outdoor and indoor and the corresponding annual effective dose rates and total excess lifetime cancer risk) were estimated to assess the radiological hazards. The total excess lifetime cancer risk (ELCR) has been calculated and found to be high in all samples, which related to high radioactivity, representing radiological risk for the health of the population. - Highlights: • Level of radioactivity of phosphate rocks and by-products samples. • The radiological health hazard parameters. • Radiological risk to the health of the population. • The excess lifetime cancer risk factor.

Active site of Zn2+-dependent sn-glycerol-1-phosphate dehydrogenase from Aeropyrum pernix K1

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Jin-Suk Han

2005-01-01

Full Text Available The enzyme sn-glycerol-1-phosphate dehydrogenase (Gro1PDH, EC 1.1.1.261 is key to the formation of the enantiomeric configuration of the glycerophosphate backbone (sn-glycerol-1-phosphate of archaeal ether lipids. This enzyme catalyzes the reversible conversion between dihydroxyacetone phosphate and glycerol-1-phosphate. To date, no information about the active site and catalytic mechanism of this enzyme has been reported. Using the sequence and structural information for glycerol dehydrogenase, we constructed six mutants (D144N, D144A, D191N, H271A, H287A and D191N/H271A of Gro1PDH from Aeropyrum pernix K1 and examined their characteristics to clarify the active site of this enzyme. The enzyme was found to be a zinc-dependent metalloenzyme, containing one zinc ion for every monomer protein that was essential for activity. Site-directed mutagenesis of D144 increased the activity of the enzyme. Mutants D144N and D144A exhibited low affinity for the substrates and higher activity than the wild type, but their affinity for the zinc ion was the same as that of the wild type. Mutants D191N, H271A and H287A had a low affinity for the zinc ion and a low activity compared with the wild type. The double mutation, D191N/ H271A, had no enzyme activity and bound no zinc. From these results, it was clarified that residues D191, H271 and H287 participate in the catalytic activity of the enzyme by binding the zinc ion, and that D144 has an effect on substrate binding. The structure of the active site of Gro1PDH from A. pernix K1 seems to be similar to that of glycerol dehydrogenase, despite the differences in substrate specificity and biological role.

High-resolution crystal structures of the photoreceptor glyceraldehyde 3-phosphate dehydrogenase (GAPDH) with three and four-bound NAD molecules

Science.gov (United States)

Baker, Bo Y; Shi, Wuxian; Wang, Benlian; Palczewski, Krzysztof

2014-01-01

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes the oxidative phosphorylation of d-glyceraldehyde 3-phosphate (G3P) into 1,3-diphosphoglycerate (BGP) in the presence of the NAD cofactor. GAPDH is an important drug target because of its central role in glycolysis, and nonglycolytic processes such as nuclear RNA transport, DNA replication/repair, membrane fusion and cellular apoptosis. Recent studies found that GAPDH participates in the development of diabetic retinopathy and its progression after the cessation of hyperglycemia. Here, we report two structures for native bovine photoreceptor GAPDH as a homotetramer with differing occupancy by NAD, bGAPDH(NAD)4, and bGAPDH(NAD)3. The bGAPDH(NAD)4 was solved at 1.52 Å, the highest resolution for GAPDH. Structural comparison of the bGAPDH(NAD)4 and bGAPDH(NAD)3 models revealed novel details of conformational changes induced by cofactor binding, including a loop region (residues 54–56). Structure analysis of bGAPDH confirmed the importance of Phe34 in NAD binding, and demonstrated that Phe34 was stabilized in the presence of NAD but displayed greater mobility in its absence. The oxidative state of the active site Cys149 residue is regulated by NAD binding, because this residue was found oxidized in the absence of dinucleotide. The distance between Cys149 and His176 decreased upon NAD binding and Cys149 remained in a reduced state when NAD was bound. These findings provide an important structural step for understanding the mechanism of GAPDH activity in vision and its pathological role in retinopathies. PMID:25176140

Calcium phosphates: what is the evidence?

Science.gov (United States)

Larsson, Sune

2010-03-01

A number of different calcium phosphate compounds such as calcium phosphate cements and solid beta-tricalcium phosphate products have been introduced during the last decade. The chemical composition mimics the mineral phase of bone and as a result of this likeness, the materials seem to be remodeled as for normal bone through a cell-mediated process that involves osteoclastic activity. This is a major difference when compared with, for instance, calcium sulphate compounds that after implantation dissolve irrespective of the new bone formation rate. Calcium phosphates are highly biocompatible and in addition, they act as synthetic osteoconductive scaffolds after implantation in bone. When placed adjacent to bone, osteoid is formed directly on the surface of the calcium phosphate with no soft tissue interposed. Remodeling is slow and incomplete, but by adding more and larger pores, like in ultraporous beta-tricalcium phosphate, complete or nearly complete resorption can be achieved. The indications explored so far include filling of metaphyseal fracture voids or bone cysts, a volume expander in conjunction with inductive products, and as a carrier for various growth factors and antibiotics. Calcium phosphate compounds such as calcium phosphate cement and beta-tricalcium phosphate will most certainly be part of the future armamentarium when dealing with fracture treatment. It is reasonable to believe that we have so far only seen the beginning when it comes to clinical applications.

Structure of conjugated polyketone reductase from Candida parapsilosis IFO 0708 reveals conformational changes for substrate recognition upon NADPH binding.

Science.gov (United States)

Qin, Hui-Min; Yamamura, Akihiro; Miyakawa, Takuya; Kataoka, Michihiko; Nagai, Takahiro; Kitamura, Nahoko; Urano, Nobuyuki; Maruoka, Shintaro; Ohtsuka, Jun; Nagata, Koji; Shimizu, Sakayu; Tanokura, Masaru

2014-01-01

Conjugated polyketone reductase C2 (CPR-C2) from Candida parapsilosis IFO 0708, identified as a nicotinamide adenine dinucleotide phosphate (NADPH)-dependent ketopantoyl lactone reductase, belongs to the aldo-keto reductase superfamily. This enzyme reduces ketopantoyl lactone to D-pantoyl lactone in a strictly stereospecific manner. To elucidate the structural basis of the substrate specificity, we determined the crystal structures of the apo CPR-C2 and CPR-C2/NADPH complex at 1.70 and 1.80 Å resolutions, respectively. CPR-C2 adopted a triose-phosphate isomerase barrel fold at the core of the structure. Binding with the cofactor NADPH induced conformational changes in which Thr27 and Lys28 moved 15 and 5.0 Å, respectively, in the close vicinity of the adenosine 2'-phosphate group of NADPH to form hydrogen bonds. Based on the comparison of the CPR-C2/NADPH structure with 3-α-hydroxysteroid dehydrogenase and mutation analyses, we constructed substrate binding models with ketopantoyl lactone, which provided insight into the substrate specificity by the cofactor-induced structure. The results will be useful for the rational design of CPR-C2 mutants targeted for use in the industrial manufacture of ketopantoyl lactone.

Effects of Jerusalem Artichoke Powder and Sodium Carbonate as Phosphate Replacers on the Quality Characteristics of Emulsified Chicken Meatballs.

Science.gov (United States)

Öztürk, Burcu; Serdaroğlu, Meltem

2018-02-01

Today incorporation of natural ingredients as inorganic phosphate replacers has come into prominence as a novel research topic due to health concerns about phosphates. In this study, we aimed to investigate the quality of emulsified chicken meatballs produced with Jerusalem artichoke powder (JAP), either alone or in combination with sodium carbonate (SC) as sodium tripolyphosphate (STPP) replacers. The results showed that naturally dried JAP showed favorable technological properties in terms of water-oil binding and gelling. Emulsion batters formulated with JAP-SC mixture showed lower jelly and fat separation, higher water-holding capacity and higher emulsion stability than control samples with STPP. In final product, incorporation of JAP-SC mixture increased moisture and reduced lipid and energy values, and kept the pH value similar to control. Added JAP lead to increments in b* values whereas decreases L* values. Cook yield was similar to control in phosphate-free samples formulated with JAP-SC mix. Either low or medium ratios of JAP in combination with SC managed to protect most of the sensory parameters, while sensory scores tend to decrease in samples containing high levels of JAP. Addition of JAP to formulations presented samples that have equivalent behavior to phosphates in terms of lipid oxidation. In conclusion, our study confirms that utilization of JAP in combination with SC had promising effects as phosphate replacers by presenting natural solutions and providing equivalent quality to standard phosphate containing products.

Roles of phosphorylation and nucleotide binding domains in calcium transport by sarcoplasmic reticulum adenosinetriphosphatase

International Nuclear Information System (INIS)

Teruel, J.A.; Inesi, G.

1988-01-01

The roles of the phosphorylation (phosphorylated enzyme intermediate) and nucleotide binding domains in calcium transport were studied by comparing acetyl phosphate and ATP as substrates for the Ca 2+ -ATPase of sarcoplasmic reticulum vesicles. The authors found that the maximal level of phosphoenzyme obtained with either substrate is approximately 4 nmol/mg of protein, corresponding to the stoichiometry of catalytic sites in their preparation. The initial burst of phosphoenzyme formation observed in the transient state, following addition of either substrate, is accompanied by internalization of 2 mol of calcium per mole of phosphoenzyme. The internalized calcium is then translocated with a sequential pattern, independent of the substrate used. Following a rate-limiting step, the phosphoenzyme undergoes hydrolytic cleavage and proceeds to the steady-state activity which is soon back inhibited by the rise of Ca 2+ concentration in the lumen of the vesicles. When the back inhibition is released by the addition of oxalate, substrate utilization and calcium transport occur with a ratio of 1:2, independent of the substrate and its concentration. When the nucleotide binding site is derivatized with FITP, the enzyme can still utilize acetyl phosphate (but not ATP) for calcium transport. These observations demonstrate that the basic coupling mechanism of catalysis and calcium transport involves the phosphorylation and calcium binding domains, and not the nucleotide binding domain. On the other hand, occupancy of the FITC-sensitive nucleotide site is involved in kinetic regulation not only with respect to utilization of substrate for the phosphoryl transfer reaction but also for subsequent steps related to calcium translocation and phosphoenzyme turnover

Genomes of rumen bacteria encode atypical pathways for fermenting hexoses to short-chain fatty acids.

Science.gov (United States)

Hackmann, Timothy J; Ngugi, David Kamanda; Firkins, Jeffrey L; Tao, Junyi

2017-11-01

Bacteria have been thought to follow only a few well-recognized biochemical pathways when fermenting glucose or other hexoses. These pathways have been chiseled in the stone of textbooks for decades, with most sources rendering them as they appear in the classic 1986 text by Gottschalk. Still, it is unclear how broadly these pathways apply, given that they were established and delineated biochemically with only a few model organisms. Here, we show that well-recognized pathways often cannot explain fermentation products formed by bacteria. In the most extensive analysis of its kind, we reconstructed pathways for glucose fermentation from genomes of 48 species and subspecies of bacteria from one environment (the rumen). In total, 44% of these bacteria had atypical pathways, including several that are completely unprecedented for bacteria or any organism. In detail, 8% of bacteria had an atypical pathway for acetate formation; 21% of bacteria had an atypical pathway for propionate or succinate formation; 6% of bacteria had an atypical pathway for butyrate formation and 33% of bacteria had an atypical or incomplete Embden-Meyerhof-Parnas pathway. This study shows that reconstruction of metabolic pathways - a common goal of omics studies - could be incorrect if well-recognized pathways are used for reference. Furthermore, it calls for renewed efforts to delineate fermentation pathways biochemically. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Phosphate additives in food--a health risk.

Science.gov (United States)

Ritz, Eberhard; Hahn, Kai; Ketteler, Markus; Kuhlmann, Martin K; Mann, Johannes

2012-01-01

Hyperphosphatemia has been identified in the past decade as a strong predictor of mortality in advanced chronic kidney disease (CKD). For example, a study of patients in stage CKD 5 (with an annual mortality of about 20%) revealed that 12% of all deaths in this group were attributable to an elevated serum phosphate concentration. Recently, a high-normal serum phosphate concentration has also been found to be an independent predictor of cardiovascular events and mortality in the general population. Therefore, phosphate additives in food are a matter of concern, and their potential impact on health may well have been underappreciated. We reviewed pertinent literature retrieved by a selective search of the PubMed and EU databases (www.zusatzstoffe-online.de, www.codexalimentarius.de), with the search terms "phosphate additives" and "hyperphosphatemia." There is no need to lower the content of natural phosphate, i.e. organic esters, in food, because this type of phosphate is incompletely absorbed; restricting its intake might even lead to protein malnutrition. On the other hand, inorganic phosphate in food additives is effectively absorbed and can measurably elevate the serum phosphate concentration in patients with advanced CKD. Foods with added phosphate tend to be eaten by persons at the lower end of the socioeconomic scale, who consume more processed and "fast" food. The main pathophysiological effect of phosphate is vascular damage, e.g. endothelial dysfunction and vascular calcification. Aside from the quality of phosphate in the diet (which also requires attention), the quantity of phosphate consumed by patients with advanced renal failure should not exceed 1000 mg per day, according to the guidelines. Prospective controlled trials are currently unavailable. In view of the high prevalence of CKD and the potential harm caused by phosphate additives to food, the public should be informed that added phosphate is damaging to health. Furthermore, calls for labeling

Clostridium Perfringens Epsilon Toxin Binds to Membrane Lipids and Its Cytotoxic Action Depends on Sulfatide.

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Carles Gil

Full Text Available Epsilon toxin (Etx is one of the major lethal toxins produced by Clostridium perfringens types B and D, being the causal agent of fatal enterotoxemia in animals, mainly sheep and goats. Etx is synthesized as a non-active prototoxin form (proEtx that becomes active upon proteolytic activation. Etx exhibits a cytotoxic effect through the formation of a pore in the plasma membrane of selected cell targets where Etx specifically binds due to the presence of specific receptors. However, the identity and nature of host receptors of Etx remain a matter of controversy. In the present study, the interactions between Etx and membrane lipids from the synaptosome-enriched fraction from rat brain (P2 fraction and MDCK cell plasma membrane preparations were analyzed. Our findings show that both Etx and proEtx bind to lipids extracted from lipid rafts from the two different models as assessed by protein-lipid overlay assay. Lipid rafts are membrane microdomains enriched in cholesterol and sphingolipids. Binding of proEtx to sulfatide, phosphatidylserine, phosphatidylinositol (3-phosphate and phosphatidylinositol (5-phosphate was detected. Removal of the sulphate groups via sulfatase treatment led to a dramatic decrease in Etx-induced cytotoxicity, but not in proEtx-GFP binding to MDCK cells or a significant shift in oligomer formation, pointing to a role of sulfatide in pore formation in rafts but not in toxin binding to the target cell membrane. These results show for the first time the interaction between Etx and membrane lipids from host tissue and point to a major role for sulfatides in C. perfringens epsilon toxin pathophysiology.

Phosphate analysis of natural sausage casings preserved in brines with phosphate additives as inactivating agent - Method validation.

Science.gov (United States)

Wijnker, J J; Tjeerdsma-van Bokhoven, J L M; Veldhuizen, E J A

2009-01-01

Certain phosphates have been identified as suitable additives for the improvement of the microbial and mechanical properties of processed natural sausage casings. When mixed with NaCl (sodium chloride) and used under specific treatment and storage conditions, these phosphates are found to prevent the spread of foot-and-mouth disease and classical swine fever via treated casings. The commercially available Quantichrom™ phosphate assay kit has been evaluated as to whether it can serve as a reliable and low-tech method for routine analysis of casings treated with phosphate. The outcome of this study indicates that this particular assay kit has sufficient sensitivity to qualitatively determine the presence of phosphate in treated casings without interference of naturally occurring phosphate in salt used for brines in which casings are preserved.

Characterization of a calcium phosphate cement based on alpha-tricalcium phosphate obtained by wet precipitation process

International Nuclear Information System (INIS)

Thurmer, M.B.; Diehl, C.E.; Vieira, R.S.; Coelho, W.T.G.; Santos, L.A.

2012-01-01

There are several systems of calcium phosphate cements being studied. Those based on alpha-tricalcium phosphate are of particular interest. After setting they produce calcium deficient hydroxyapatite similar to bone like hydroxyapatite. This work aims to obtain alpha-tricalcium phosphate powders by the wet precipitation process, using calcium nitrate and phosphoric acid as reagents. This powder was characterized by infrared spectroscopy, X-ray diffraction and particle size distribution. In order to prepare the calcium phosphate cement, the powder was mixed with an accelerator in an aqueous solution. The mechanical properties of the cement were assessed and it was evaluated by means of apparent density, X-ray diffraction and scanning electron microscopy. The described method produced crystalline alpha-tricalcium phosphate as the major phase. The calcium phosphate cement showed high values of compression strength (50 MPa). The soaking of the cement in a simulated body fluid (SBF) formed a layer of hydroxyapatite like crystals in the surface of the samples. (author)

Calcium phosphate-gold nanoparticles nanocomposite for protein adsorption and mediator-free H{sub 2}O{sub 2} biosensor construction

Energy Technology Data Exchange (ETDEWEB)

Xu Qin [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Jiangsu Key Laboratory of Environmental Engineering and Monitoring, Yangzhou 225002 (China); Lu Guiju; Bian XiaoJun; Jin Gendi [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Wang Wei [School of Chemical and Biological Engineering, Yancheng Institute of Technology, Yancheng, 224051 (China); Hu Xiaoya, E-mail: xyhu@yzu.edu.cn [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Jiangsu Key Laboratory of Environmental Engineering and Monitoring, Yangzhou 225002 (China); Wang Yang; Yang Zhanjun [College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

2012-04-01

This work reports a new method for the preparation and application of a kind of biocompatible calcium phosphate-gold nanoparticles (Ca{sub 3}(PO{sub 4}){sub 2}-AuNPs) nanocomposite. UV-vis spectroscopy and transmittance electron microscopy (TEM) have been used to monitor the formation process of the nanocomposite and to examine the interaction between calcium phosphate and gold nanoparticles (AuNPs). The nanocomposite has multiple sites and improved conductivity which make it suitable for the binding of proteins to construct electrochemical sensors. Myoglobin (Mb) adsorbed on the nanocomposite retained its native structure which was proved by Fourier transform infrared spectroscopy (FTIR). Direct electron transfer between the adsorbed Mb and the electrode was observed. Further results demonstrated that the adsorbed Mb has good electrocatalytic activity towards the reduction of H{sub 2}O{sub 2} in the absence of any mediator. Highlights: Black-Right-Pointing-Pointer Using gelatin modified gold nanoparticles to prepare needle-like calcium phosphate. Black-Right-Pointing-Pointer Calcium phosphate provides multiple sites for protein adsorption. Black-Right-Pointing-Pointer Gold nanoparticles act as electron tunneling. Black-Right-Pointing-Pointer Myoglobin adsorbed on the material showed direct electrochemistry and good catalysis.

Classification of a Haemophilus influenzae ABC Transporter HI1470/71 through Its Cognate Molybdate Periplasmic Binding Protein, MolA

Energy Technology Data Exchange (ETDEWEB)

Tirado-Lee, Leidamarie; Lee, Allen; Rees, Douglas C.; Pinkett, Heather W. (CIT); (NWU)

2014-10-02

molA (HI1472) from H. influenzae encodes a periplasmic binding protein (PBP) that delivers substrate to the ABC transporter MolB{sub 2}C{sub 2} (formerly HI1470/71). The structures of MolA with molybdate and tungstate in the binding pocket were solved to 1.6 and 1.7 {angstrom} resolution, respectively. The MolA-binding protein binds molybdate and tungstate, but not other oxyanions such as sulfate and phosphate, making it the first class III molybdate-binding protein structurally solved. The {approx}100 {mu}M binding affinity for tungstate and molybdate is significantly lower than observed for the class II ModA molybdate-binding proteins that have nanomolar to low micromolar affinity for molybdate. The presence of two molybdate loci in H. influenzae suggests multiple transport systems for one substrate, with molABC constituting a low-affinity molybdate locus.

Phosphate solubilization and multiple plant growth promoting ...

African Journals Online (AJOL)

Phosphate solubilizing efficiencies of the strains were analyzed using different insoluble phosphorus sources and the results show that most isolates released a substantial amount of soluble phosphate from tricalcium phosphate, rock phosphate and bone meal. Screening for multiple plant growth promoting attributes ...

Phosphate steering by Flap Endonuclease 1 promotes 5′-flap specificity and incision to prevent genome instability

KAUST Repository

Tsutakawa, Susan E.

2017-06-27

DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5\\'-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5\\'-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5\\'polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via phosphate steering\\', basic residues energetically steer an inverted ss 5\\'-flap through a gateway over FEN1\\'s active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (GAA) repeat expansions in vivo, implying failed phosphate-steering promotes an unanticipated lagging-strand template-switch mechanism during replication. Thus, phosphate steering is an unappreciated FEN1 function that enforces 5\\'-flap specificity and catalysis, preventing genomic instability.

A new human NHERF1 mutation decreases renal phosphate transporter NPT2a expression by a PTH-independent mechanism.

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Marie Courbebaisse

Full Text Available BACKGROUND: The sodium-hydrogen exchanger regulatory factor 1 (NHERF1 binds to the main renal phosphate transporter NPT2a and to the parathyroid hormone (PTH receptor. We have recently identified mutations in NHERF1 that decrease renal phosphate reabsorption by increasing PTH-induced cAMP production in the renal proximal tubule. METHODS: We compared relevant parameters of phosphate homeostasis in a patient with a previously undescribed mutation in NHERF1 and in control subjects. We expressed the mutant NHERF1 protein in Xenopus Oocytes and in cultured cells to study its effects on phosphate transport and PTH-induced cAMP production. RESULTS: We identified in a patient with inappropriate renal phosphate reabsorption a previously unidentified mutation (E68A located in the PDZ1 domain of NHERF1.We report the consequences of this mutation on NHERF1 function. E68A mutation did not modify cAMP production in the patient. PTH-induced cAMP synthesis and PKC activity were not altered by E68A mutation in renal cells in culture. In contrast to wild-type NHERF1, expression of the E68A mutant in Xenopus oocytes and in human cells failed to increase phosphate transport. Pull down experiments showed that E68A mutant did not interact with NPT2a, which robustly interacted with wild type NHERF1 and previously identified mutants. Biotinylation studies revealed that E68A mutant was unable to increase cell surface expression of NPT2a. CONCLUSIONS: Our results indicate that the PDZ1 domain is critical for NHERF1-NPT2a interaction in humans and for the control of NPT2a expression at the plasma membrane. Thus we have identified a new mechanism of renal phosphate loss and shown that different mutations in NHERF1 can alter renal phosphate reabsorption via distinct mechanisms.

Deciphering common recognition principles of nucleoside mono/di and tri-phosphates binding in diverse proteins via structural matching of their binding sites.

Science.gov (United States)

Bhagavat, Raghu; Srinivasan, Narayanaswamy; Chandra, Nagasuma

2017-09-01

Nucleoside triphosphate (NTP) ligands are of high biological importance and are essential for all life forms. A pre-requisite for them to participate in diverse biochemical processes is their recognition by diverse proteins. It is thus of great interest to understand the basis for such recognition in different proteins. Towards this, we have used a structural bioinformatics approach and analyze structures of 4677 NTP complexes available in Protein Data Bank (PDB). Binding sites were extracted and compared exhaustively using PocketMatch, a sensitive in-house site comparison algorithm, which resulted in grouping the entire dataset into 27 site-types. Each of these site-types represent a structural motif comprised of two or more residue conservations, derived using another in-house tool for superposing binding sites, PocketAlign. The 27 site-types could be grouped further into 9 super-types by considering partial similarities in the sites, which indicated that the individual site-types comprise different combinations of one or more site features. A scan across PDB using the 27 structural motifs determined the motifs to be specific to NTP binding sites, and a computational alanine mutagenesis indicated that residues identified to be highly conserved in the motifs are also most contributing to binding. Alternate orientations of the ligand in several site-types were observed and rationalized, indicating the possibility of some residues serving as anchors for NTP recognition. The presence of multiple site-types and the grouping of multiple folds into each site-type is strongly suggestive of convergent evolution. Knowledge of determinants obtained from this study will be useful for detecting function in unknown proteins. Proteins 2017; 85:1699-1712. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Phosphate and phosphate fertilizer sector: structure and future prospects. [Uranium recovery

Energy Technology Data Exchange (ETDEWEB)

Zenaidi, B

1981-12-01

A statement of the past evolution of this sector's structure is given. Various prospective studies which have been made are reviewed and lead to the precision of the phosphate requirement in the year 2000 which is between 200 and 250 Mt. Only a small section p. 696-697 is devoted to recovery of uranium contained in phosphate and prospects in this field are given.

Better prospects for phosphate production

Energy Technology Data Exchange (ETDEWEB)

1980-06-01

The extraction of uranium as a by product of phosphate production is discussed. Techniques being commercially developed are described. The trend towards the wet process, in which sulphuric acid is used to dissolve the phosphate, producing phosphoric acid, is also the preferred method for uranium recovery. Recovery from a wet process phosphoric acid stream, integrated with phosphate fertilizer manufacture, is becoming increasingly commercially viable for the production of yellow-cake.

RNA binding specificity of Ebola virus transcription factor VP30.

Science.gov (United States)

Schlereth, Julia; Grünweller, Arnold; Biedenkopf, Nadine; Becker, Stephan; Hartmann, Roland K

2016-09-01

The transcription factor VP30 of the non-segmented RNA negative strand Ebola virus balances viral transcription and replication. Here, we comprehensively studied RNA binding by VP30. Using a novel VP30:RNA electrophoretic mobility shift assay, we tested truncated variants of 2 potential natural RNA substrates of VP30 - the genomic Ebola viral 3'-leader region and its complementary antigenomic counterpart (each ∼155 nt in length) - and a series of other non-viral RNAs. Based on oligonucleotide interference, the major VP30 binding region on the genomic 3'-leader substrate was assigned to the internal expanded single-stranded region (∼ nt 125-80). Best binding to VP30 was obtained with ssRNAs of optimally ∼ 40 nt and mixed base composition; underrepresentation of purines or pyrimidines was tolerated, but homopolymeric sequences impaired binding. A stem-loop structure, particularly at the 3'-end or positioned internally, supports stable binding to VP30. In contrast, dsRNA or RNAs exposing large internal loops flanked by entirely helical arms on both sides are not bound. Introduction of a 5´-Cap(0) structure impaired VP30 binding. Also, ssDNAs bind substantially weaker than isosequential ssRNAs and heparin competes with RNA for binding to VP30, indicating that ribose 2'-hydroxyls and electrostatic contacts of the phosphate groups contribute to the formation of VP30:RNA complexes. Our results indicate a rather relaxed RNA binding specificity of filoviral VP30, which largely differs from that of the functionally related transcription factor of the Paramyxoviridae which binds to ssRNAs as short as 13 nt with a preference for oligo(A) sequences.

The Oxygen Isotopic Composition of Phosphate: A Tracer for Phosphate Sources and Cycling

Energy Technology Data Exchange (ETDEWEB)

Mclaughlin, K. [Southern California Coastal Water Research Project, Costa Mesa, University of California, CA (United States); Young, M. B.; Paytan, A.; Kendall, C. [U.S. Geological Survey, University of California, CA (United States)

2013-05-15

Phosphorus (P) is a limiting macro-nutrient for primary productivity and anthropogenic P-loading to aquatic ecosystems is one of the leading causes of eutrophication in many ecosystems throughout the world. Because P has only one stable isotope, traditional isotope techniques are not possible for tracing sources and cycling of P in aquatic systems. However, much of the P in nature is bonded to four oxygen (O) atoms as orthophosphate (PO{sub 4}{sup 3-}). The P-O bonds in orthophosphate are strongly resistant to inorganic hydrolysis and do not exchange oxygen with water without biological mediation (enzyme-mediated recycling). Thus, the oxygen isotopic composition of dissolved inorganic phosphate ({delta}{sup 18}O{sub p}) may be used as a tracer for phosphate sources and cycling in aquatic ecosystems. Recently, several studies have been conducted utilizing {delta}{sup 18}O{sub p} as a tracer for phosphate sources and cycling in various aquatic environments. Specifically, work to date indicates that {delta}{sup 18}O{sub p} is useful for determining sources of phosphate to aquatic systems if these sources have unique isotopic signatures and phosphate cycling within the system is limited compared to input fluxes. In addition, because various processes imprint specific fractionation effects, the {delta}{sup 18}O{sub p} tracer can be utilized to determine the degree of phosphorous cycling and processing through the biomass. This chapter reviews several of these studies and discusses the potential to utilize the {delta}{sup 18}O{sub p} of phosphate in rivers and streams. (author)

High-Dose Mannose-Binding Lectin Therapy for Ebola Virus Infection

Science.gov (United States)

2010-06-01

host defense against a wide range of viral and other pathogens. MBL is a C-type lectin that recognizes hexose sugars including man- nose, glucose...should be evaluatedmore broadly as an immunotherapeutic agent for a wide spectrum of glycosylated pathogens. MATERIALS AND METHODS Production and... coagulation mod- ulators, antisense technologies, therapeutic antibodies and Table 1. Pharmacokinetic Parameters of Low- vs High-Dose Recombinant Human

Occurrence and functioning of phosphate solubilizing ...

African Journals Online (AJOL)

Occurrence and functioning of phosphate solubilizing microorganisms from oil palm tree ( Elaeis guineensis ) rhizosphere in Cameroon. ... While the use of soluble mineral phosphate fertilizers is the obvious best means to combat phosphate ... in order to improve agricultural production, using low inputs technology. Isolates ...

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

Energy Technology Data Exchange (ETDEWEB)

Park, Jaeok [McGill University, 3655 Promenade Sir William Osler, Montreal, QC H3G 1Y6 (Canada); Lin, Yih-Shyan [McGill University, 801 Rue Sherbrooke Ouest, Montreal, QC H3A 0B8 (Canada); Tsantrizos, Youla S. [McGill University, 3655 Promenade Sir William Osler, Montreal, QC H3G 1Y6 (Canada); McGill University, 801 Rue Sherbrooke Ouest, Montreal, QC H3A 0B8 (Canada); McGill University, 3649 Promenade Sir William Osler, Montreal, QC H3G 0B1 (Canada); Berghuis, Albert M., E-mail: albert.berghuis@mcgill.ca [McGill University, 3655 Promenade Sir William Osler, Montreal, QC H3G 1Y6 (Canada); McGill University, 3649 Promenade Sir William Osler, Montreal, QC H3G 0B1 (Canada); McGill University, 3775 Rue University, Montreal, QC H3A 2B4 (Canada)

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.

A radioisotope dilution assay for unlabelled vitamin B12-intrinsic factor complex employing the binding intrinsic factor antibody: probable evidence for two types of binding antibody

International Nuclear Information System (INIS)

Jacob, E.; O'Brien, H.A.W.; Mollin, D.L.

1977-01-01

A new radioisotope dilution assay for vitamin B 12 -intrinsic factor complex is described. The method is based on the use of the binding type intrinsic antibody (the binding reagent), which when combined with the intrinsic factor-vitamin B 12 complex (labelled ligand), is quantitatively adsorbed onto zirconium phosphate gel pH 6.25. The new assay has been shown to provide a measure of intrinsic factor comparable with other intrinsic factor assays, but it has the important advantage of being able to measure the unlabelled vitamin B 12 -intrinsic factor complex (unlabelled ligand), and will, therefore, be valuable in the study of physiological events in the gastrointestinal tract. During the study, it was found that there is some evidence for at least two types of binding intrinsic factor antibody: One which combines preferentially with the intrinsic factor-vitamin B 12 complex and one which combines equally well with this complex or with free intrinsic factor. (author)

PHOSPHATE CRYSTALLURIA IN VARIOUS FORMS OF UROLITHIASIS AND POSSIBILITIES OF ITS PROGNOSTICATION IN PATIENTS WITH PHOSPHATE STONES

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O. V. Konstantinova

2017-01-01

Full Text Available Purpose. Definition of types of crystalluria in various forms of urolithiasis and biochemical signs of phosphate crystals in the urine, while phosphate urolithiasis (infectious origin.Patients and methods. The study involved 144 patients with recurrent urolithiasis — 75 women and 69 men. Of these, 46 — diagnosed calculi with uric acid, 44 — calcium oxalate or mixed with a prevalence of calcium oxalate, in 54 — phosphate rocks (carbonate-apatite and/or struvite. The age of patients ranged from 21 to 74 years. 93 people have been under long-term, within 2–15 years, outpatient observation. The examination included the collection of anamnesis, general and microbiological analysis of urine, biochemical blood serum and urine on 10 indicators, reflecting renal function, state of the protein, water and electrolyte metabolism, uric acid metabolism, the chemical composition of the stone analysis.Results. It was found that in patients with calcium oxalate stones phosphaturia has been diagnosed in 2% of cases. And, along with calcium phosphate crystals they had oxalate crystals. In patients with phosphate urolithiasis phosphaturia observed in 96% of patients, in two patients (4% they determined except phosphates also oxalate salt in urine sediment. Patients with phosphate urolithiasis at occurrence of phosphate crystalluria have metabolic state changes: increased serum uric acid concentration from 0.322 ± 0.009 to 0.367 ± 0.018 mmol/l daily renal excretion of inorganic phosphate 23.94 ± 2.93 mmol/day to 32.12 ± 4.39 mmol/day, and reduced total calcium content in urine 6.61 ± 0.94 mmol/day to 3.37 ± 0.89 mmol/day. The results led to the following conclusion.Conclusion. Biochemical signs of occurrence of phosphate crystalluria in patients with stones of infectious origin can be: the approaching level of excretion in the urine of inorganic phosphates to 32,12 ± 4,39 mmol/day, serum uric acid concentration to 0,367 ± 0,018 mmol/l, and the

on association of trialkyl phosphates

International Nuclear Information System (INIS)

Petkovic, D.M.; Maksimovic, Z.B.

1976-01-01

The association constants of tri-n-butyl (TBP), tri-n-propyl (TPP) and triethyl phosphate (TEP) with chloroform, carbon tetrachloride and benzene were determined by dielectric constant, proton magnetic resonance and vapor pressure measurements. Correlation of the trialkyl phosphate-chloroform association constants, using the Hammett equation, showed their increase with the number of carbon atoms in the aliphatic radicals. The change of trialkyl phosphate reactivity with temperature was used to determine the thermodynamic quantities. (author)

Bio-treatment of phosphate from synthetic wastewater using ...

African Journals Online (AJOL)

In this study, the efficient phosphate utilizing isolates were used to remove phosphate from synthetic phosphate wastewater was tested using batch scale process. Hence the objective of the present study was to examine the efficiency of bacterial species individually for the removal of phosphate from synthetic phosphate ...

Infrared-spectroscopy analysis of zinc phosphate and nickel and manganese modified zinc phosphate coatings on electrogalvanized steel

International Nuclear Information System (INIS)

Fernandes, Kirlene Salgado; Alvarenga, Evandro de Azevedo; Lins, Vanessa de Freitas Cunha

2011-01-01

Hopeite-type phosphate coatings in which zinc is partially replaced by other metals like manganese and nickel are of great interest for the automotive and home appliance industries. Such industries use phosphate conversion coatings on galvanized steels in association with cataphoretic electro painting. Zinc phosphates modified with manganese and nickel are isomorphic with the hopeite, and the phase identification using X-ray diffraction is difficult. In this paper, the phosphate coatings are identified using the Fourier transform infrared spectroscopy (FTIR). (author)

Lysine 356 is a critical residue for binding the C-6 phospho group of fructose 2,6-bisphosphate to the fructose-2,6-bisphosphatase domain of rat liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

Science.gov (United States)

Li, L; Lin, K; Correia, J J; Pilkis, S J

1992-08-15

Lysine 356 has been implicated by protein modification studies as a fructose-2,6-bisphosphate binding site residue in the 6-phosphofructo-2-kinase domain of rat liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (Kitajima, S., Thomas, H., and Uyeda, K. (1985) J. Biol. Chem. 260, 13995-14002). However, Lys-356 is found in the fructose-2,6-bisphosphatase domain (Bazan, F., Fletterick, R., and Pilkis, S. J. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 9642-9646). In order to ascertain whether Lys-356 is involved in fructose-2,6-bisphosphatase catalysis and/or domain/domain interactions of the bifunctional enzyme, Lys-356 was mutated to Ala, expressed in Escherichia coli, and then purified to homogeneity. Circular dichroism experiments indicated that the secondary structure of the Lys-356-Ala mutant was not significantly different from that of the wild-type enzyme. The Km for fructose 2,6-bisphosphate and the Ki for the noncompetitive inhibitor, fructose 6-phosphate, for the fructose-2,6-bisphosphatase of the Lys-356-Ala mutant were 2700- and 2200-fold higher, respectively, than those of the wild-type enzyme. However, the maximal velocity and the Ki for the competitive product inhibitor, inorganic phosphate, were unchanged compared to the corresponding values of the wild-type enzyme. Furthermore, in contrast to the wild-type enzyme, which exhibits substrate inhibition, there was no inhibition by substrate of the Lys-356-Ala mutant. In the presence of saturating substrate, inorganic phosphate, which acts by relieving fructose-6-phosphate and substrate inhibition, is an activator of the bisphosphatase. The Ka for inorganic phosphate of the Lys-356-Ala mutant was 1300-fold higher than that of the wild-type enzyme. The kinetic properties of the 6-phosphofructo-2-kinase of the Lys-356-Ala mutant were essentially identical with that of the wild-type enzyme. The results demonstrate that: 1) Lys-356 is a critical residue in fructose-2,6-bisphosphatase for binding the 6

Isolation, identification, and synthesis of 2-carboxyarabinitol 1-phosphate, a diurnal regulator of ribulase-bisphosphate carboxylase activity

International Nuclear Information System (INIS)

Berry, J.A.; Lorimer, G.H.; Pierce, J.; Seemann, J.R.; Meek, J.; Freas, S.

1987-01-01

The diurnal change in activity of ribulose 1,5-bisphosphate (Rbu-1,5-P 2 ) carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing); EC 4.1.1.39] of leaves of Phaseolus vulgaris is regulated (in part) by mechanisms that control the level of an endogenous inhibitor that binds tightly to the activated (carbamoylated) form of Rbu-1,5-P 2 carboxylase. This inhibitor was extracted from leaves and copurified with the Rbu-1,5-P 2 carboxylase of the leaves. Further purification by ion-exchange chromatography, adsorption to purified Rbu-1,5-P 2 carboxylase, barium precipitation, and HPLC separation yielded a phosphorylated compound that was a strong inhibitor of Rbu-1,5-P 2 carboxylase. The compound was analyzed by GC/MS, 13 C NMR, and 1 H NMR and shown to be 2-carboxyarabinitol 1-phosphate [(2-C-phosphohydroxymethyl)-D-ribonic acid]. The structure of the isolated compound differs from the Rbu-1,5-P 2 carboxylase transition-state analogue 2-carboxyarabinitol 1,5-bisphosphate only by the lack of the C-5 phosphate group. This difference results in a higher binding constant for the monophosphate compared with the bisphosphate. The less tightly bound compound acts in a light-dependent, reversible regulation of Rbu-1,5-P 2 carboxylase activity in vivo

Application of Calcium Phosphate Materials in Dentistry

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Jabr S. Al-Sanabani

2013-01-01

Full Text Available Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1 application of calcium phosphate into various fields in dentistry; (2 improving mechanical properties of calcium phosphate; (3 biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields.

The interaction of 2,3-diphosphoglycerate with various human hemoglobins

Science.gov (United States)

Bunn, H. Franklin; Briehl, Robin W.

1970-01-01

Oxygen equilibria were measured on a number of human hemoglobins, which had been “stripped” of organic phosphates and isolated by column chromatography. In the presence of 2 × 10-4 M 2,3-diphosphoglycerate (2,3-DPG), the P50 of hemoglobins A, A2, S, and C increased about twofold, signifying a substantial and equal decrease in oxygen affinity. Furthermore, hemoglobins Chesapeake and MMilwaukee-1 which have intrinsically high and low oxygen affinities, respectively, also showed a twofold increase in P50 in the presence of 2 × 10-4 M 2,3-DPG. In comparison to these, hemoglobins AIC and F were less reactive with 2,3-DPG while hemoglobin FI showed virtually no reactivity. The N-terminal amino of each β-chain of hemoglobin AIC is linked to a hexose. In hemoglobin FI the N-terminal amino of each γ-chain is acetylated. These results suggest that the N-terminal amino groups of the non-α-chains are involved in the binding of 2,3-DPG to hemoglobin. PMID:5422014

Phosphate acquisition efficiency and phosphate starvation tolerance ...

Indian Academy of Sciences (India)

3Department of Genetics and Plant Breeding, College of Agriculture, Lembucherra, Tripura 799 ... vated in soil like red and lateritic or acid, with low soluble phosphate content. ..... activation of genes involved in the adaptation of Arabidopsis to.

SINTESIS PATI SAGU IKATAN SILANG FOSFAT BERDERAJAT SUBSTITUSI FOSFAT TINGGI DALAM SUASANA ASAM [Synthesis of Cross-Linked Sago Starch Phosphate with the Highest Degree of Substitution of Phosphate Under Acidic Condition

Directory of Open Access Journals (Sweden)

Jorion Romengga*

2011-12-01

Full Text Available Cross-linked sago starch phosphate (SgP with high phosphorus contents was successfully synthesized by reacting sago with a mixture of primary and secondary sodium phosphates under acidic condition. The experimental variables investigated include pH, temperature, reaction time, and mixture rate. The physicochemical properties evaluated were moisture, swelling power, water binding capacity, transmittance (%T and percent amylose (%Am, while the pasting properties examined were pasting time, pasting temperature, viscosity at peak, final, and setback. The granule structure was observed by scanning electron microscope and X-ray diffraction. The results showed that the maximum degree of phosphate substitution was obtained at pH of 6.50, 40°C, 20 minutes of reaction time and 300 rpm of mixing rate. The physicochemical (%T and %Am and pasting (viscosity at peak, final, and setback properties of SgP were significantly different (P<0.01 from Sg. Structure of SgP was characterized by FT-IR and the results indicated a new absorption peak at 2362.87 cm-1 which was characterized as the phospho-diester (RO-PO3-R’ stretching vibration. In the fingerprint area, there were two new absorption peaks at 1242.05 and 989.79 cm-1 which were characterized as the P=O and C-O-P vibration, respectively. Sago granules were substantially altered after cross-linking.

Most consumed processed foods by patients on hemodialysis: Alert for phosphate-containing additives and the phosphate-to-protein ratio.

Science.gov (United States)

Watanabe, Marcela T; Araujo, Raphael M; Vogt, Barbara P; Barretti, Pasqual; Caramori, Jacqueline C T

2016-08-01

Hyperphosphatemia is common in patients with chronic kidney disease (CKD) stages IV and V because of decreased phosphorus excretion. Phosphatemia is closely related to dietary intake. Thus, a better understanding of sources of dietary phosphate consumption, absorption and restriction, particularly inorganic phosphate found in food additives, is key to prevent consequences of this complication. Our aims were to investigate the most commonly consumed processed foods by patients with CKD on hemodialysis, to analyze phosphate and protein content of these foods using chemical analysis and to compare these processed foods with fresh foods. We performed a cross-sectional descriptive analytical study using food frequency questionnaires to rank the most consumed industrialized foods and beverages. Total phosphate content was determined by metavanadate colorimetry, and nitrogen content was determined by the Kjeldahl method. Protein amounts were estimated from nitrogen content. The phosphate-to-protein ratio (mg/g) was then calculated. Processed meat protein and phosphate content were compared with the nutritional composition of fresh foods using the Brazilian Food Composition Table. Phosphate measurement results were compared with data from the Food Composition Table - Support for Nutritional Decisions. An α level of 5% was considered significant. Food frequency questionnaires were performed on 100 patients (mean age, 59 ± 14 years; 57% male). Phosphate additives were mentioned on 70% of the product labels analyzed. Proteins with phosphate-containing additives provided approximately twice as much phosphate per gram of protein compared with that of fresh foods (p processed foods are higher than those of fresh foods, as well as phosphate-to-protein ratio. A better understanding of phosphate content in foods, particularly processed foods, may contribute to better control of phosphatemia in patients with CKD. Copyright © 2016 European Society for Clinical Nutrition and

Antioxidant mechanism of milk mineral-high-affinity iron binding.

Science.gov (United States)

Allen, K; Cornforth, D

2007-01-01

Milk mineral (MM), a by-product of whey processing, is an effective antioxidant in meat systems, but the antioxidant mechanism has not been established. MM has been postulated to chelate iron and prevent iron-catalysis of lipid oxidation. The objective of this research was to examine this putative mechanism. MM was compared to sodium tripolyphosphate (STPP), calcium phosphate monobasic (CPM), and calcium pyrophosphate (CPP) to determine iron-binding capacity, sample solubility, and eluate soluble phosphorus after treating samples with a ferrous chloride standard. Scanning electron microscopy with energy-dispersive X-ray analysis was used to localize minerals on iron-treated MM particle surfaces. Histochemical staining for calcium was performed on raw and cooked ground beef samples with added MM. MM bound more iron per gram (P compounds, and was much less soluble (P iron across the MM particle surface, directly demonstrating iron binding to MM particles. Unlike other common chelating agents, such as STPP and citrate, histochemical staining demonstrated that MM remained insoluble in ground beef, even after cooking. The ability of MM to bind iron and remain insoluble may enhance its antioxidant effect by removing iron ions from solution. However, MM particles must be small and well distributed in order to adequately bind iron throughout the food system.

Pentose phosphates in nucleoside interconversion and catabolism.

Science.gov (United States)

Tozzi, Maria G; Camici, Marcella; Mascia, Laura; Sgarrella, Francesco; Ipata, Piero L

2006-03-01

Ribose phosphates are either synthesized through the oxidative branch of the pentose phosphate pathway, or are supplied by nucleoside phosphorylases. The two main pentose phosphates, ribose-5-phosphate and ribose-1-phosphate, are readily interconverted by the action of phosphopentomutase. Ribose-5-phosphate is the direct precursor of 5-phosphoribosyl-1-pyrophosphate, for both de novo and 'salvage' synthesis of nucleotides. Phosphorolysis of deoxyribonucleosides is the main source of deoxyribose phosphates, which are interconvertible, through the action of phosphopentomutase. The pentose moiety of all nucleosides can serve as a carbon and energy source. During the past decade, extensive advances have been made in elucidating the pathways by which the pentose phosphates, arising from nucleoside phosphorolysis, are either recycled, without opening of their furanosidic ring, or catabolized as a carbon and energy source. We review herein the experimental knowledge on the molecular mechanisms by which (a) ribose-1-phosphate, produced by purine nucleoside phosphorylase acting catabolically, is either anabolized for pyrimidine salvage and 5-fluorouracil activation, with uridine phosphorylase acting anabolically, or recycled for nucleoside and base interconversion; (b) the nucleosides can be regarded, both in bacteria and in eukaryotic cells, as carriers of sugars, that are made available though the action of nucleoside phosphorylases. In bacteria, catabolism of nucleosides, when suitable carbon and energy sources are not available, is accomplished by a battery of nucleoside transporters and of inducible catabolic enzymes for purine and pyrimidine nucleosides and for pentose phosphates. In eukaryotic cells, the modulation of pentose phosphate production by nucleoside catabolism seems to be affected by developmental and physiological factors on enzyme levels.

The crystal structure of galactitol-1-phosphate 5-dehydrogenase from Escherichia coli K12 provides insights into its anomalous behavior on IMAC processes.

Science.gov (United States)

Esteban-Torres, María; Alvarez, Yanaisis; Acebrón, Iván; de las Rivas, Blanca; Muñoz, Rosario; Kohring, Gert-Wieland; Roa, Ana María; Sobrino, Mónica; Mancheño, José M

2012-09-21

Endogenous galactitol-1-phosphate 5-dehydrogenase (GPDH) (EC 1.1.1.251) from Escherichia coli spontaneously interacts with Ni(2+)-NTA matrices becoming a potential contaminant for recombinant, target His-tagged proteins. Purified recombinant, untagged GPDH (rGPDH) converted galactitol into tagatose, and d-tagatose-6-phosphate into galactitol-1-phosphate, in a Zn(2+)- and NAD(H)-dependent manner and readily crystallized what has permitted to solve its crystal structure. In contrast, N-terminally His-tagged GPDH was marginally stable and readily aggregated. The structure of rGPDH revealed metal-binding sites characteristic from the medium-chain dehydrogenase/reductase protein superfamily which may explain its ability to interact with immobilized metals. The structure also provides clues on the harmful effects of the N-terminal His-tag. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Meal phosphate variability does not support fixed dose phosphate binder schedules for patients treated with peritoneal dialysis: a prospective cohort study.

Science.gov (United States)

Leung, Simon; McCormick, Brendan; Wagner, Jessica; Biyani, Mohan; Lavoie, Susan; Imtiaz, Rameez; Zimmerman, Deborah

2015-12-09

Removal of phosphate by peritoneal dialysis is insufficient to maintain normal serum phosphate levels such that most patients must take phosphate binders with their meals. However, phosphate 'counting' is complicated and many patients are simply prescribed a specific dose of phosphate binders with each meal. Therefore, our primary objective was to assess the variability in meal phosphate content to determine the appropriateness of this approach. In this prospective cohort study, adult patients with ESRD treated with peritoneal dialysis and prescribed phosphate binder therapy were eligible to participate. Participants were excluded from the study if they were unable to give consent, had hypercalcemia, were visually or hearing impaired or were expected to receive a renal transplant during the time of the study. After providing informed consent, patients kept a 3-day diet diary that included all foods and beverages consumed in addition to portion sizes. At the same time, patients documented the amount of phosphate binders taken with each meal. The phosphate content of the each meal was estimated using ESHA Food Processor SQL Software by a registered dietitian. Meal phosphate and binder variability were estimated by the Intra Class Correlation Coefficient (ICC) where 0 indicates maximal variability and 1 indicates no variability. Seventy-eight patients consented to participate in the study; 18 did not complete the study protocol. The patients were 60 (± 17) years, predominately male (38/60) and Caucasian (51/60). Diabetic nephropathy was the most common cause of end stage kidney disease. The daily phosphate intake including snacks ranged from 959 ± 249 to 1144 ± 362 mg. The phosphate ICC by meal: breakfast 0.63, lunch 0.16; supper 0.27. The phosphate binder ICC by meal: breakfast 0.68, lunch 0.73, supper 0.67. The standard prescription of a set number of phosphate binders with each meal is not supported by the data; patients do not appear to be adjusting their

Comparative study on in vitro biocompatibility of synthetic octacalcium phosphate and calcium phosphate ceramics used clinically.

Science.gov (United States)

Morimoto, Shinji; Anada, Takahisa; Honda, Yoshitomo; Suzuki, Osamu

2012-08-01

The present study was designed to investigate the extent to which calcium phosphate bone substitute materials, including osteoconductive octacalcium phosphate (OCP), display cytotoxic and inflammatory responses based on their dissolution in vitro. Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ceramics, which are clinically used, as well as dicalcium phosphate dihydrate (DCPD) and synthesized OCP were compared. The materials were well characterized by chemical analysis, x-ray diffraction and Fourier transform infrared spectroscopy. Calcium and phosphate ion concentrations and the pH of culture media after immersion of the materials were determined. The colony forming rate of Chinese hamster lung fibroblasts was estimated with extraction of the materials. Proliferation of bone marrow stromal ST-2 cells and inflammatory cytokine TNF-α production by THP-1 cells grown on the material-coated plates were examined. The materials had characteristics that corresponded to those reported. DCPD was shown to dissolve the most in the culture media, with a marked increase in phosphate ion concentration and a reduction in pH. ST-2 cells proliferated well on the materials, with the exception of DCPD, which markedly inhibited cellular growth. The colony forming capacity was the lowest on DCPD, while that of the other calcium phosphates was not altered. In contrast, TNF-α was not detected even in cells grown on DCPD, suggesting that calcium phosphate materials are essentially non-inflammatory, while the solubility of the materials can affect osteoblastic and fibroblastic cellular attachment. These results indicate that OCP is biocompatible, which is similar to the materials used clinically, such as HA. Therefore, OCP could be clinically used as a biocompatible bone substitute material.

Functional identification of an Arabidopsis snf4 ortholog by screening for heterologous multicopy suppressors of snf4 deficiency in yeast

DEFF Research Database (Denmark)

Kleinow, T.; Bhalerao, R.; Breuer, F.

2000-01-01

Yeast Snf4 is a prototype of activating gamma-subunits of conserved Snf1/AMPK-related protein kinases (SnRKs) controlling glucose and stress signaling in eukaryotes. The catalytic subunits of Arabidopsis SnRKs, AKIN10 and AKIN11, interact with Snf4 and suppress the snf1 and snf4 mutations in yeast....... By expression of an Arabidopsis cDNA library in yeast, heterologous multicopy snf4 suppressors were isolated. In addition to AKIN10 and AKIN11, the deficiency of yeast snf4 mutant to grown on non-fermentable carbon source was suppressed by Arabidopsis Myb30, CAAT-binding factor Hap3b, casein kinase I, zinc......-finger factors AZF2 and ZAT10, as well as orthologs of hexose/UDP-hexose transporters, calmodulin, SMC1-cohesin and Snf4. Here we describe the characterization of AtSNF4, a functional Arabidopsis Snf4 ortholog, that interacts with yeast Snf1 and specifically binds to the C-terminal regulatory domain...

Molecular binding thermodynamics of spherical guests by β-cyclodextrins bearing aromatic substituents

Energy Technology Data Exchange (ETDEWEB)

Li, Nan; Chen, Yong; Zhang, Ying-Ming; Wang, Li-Hua; Mao, Wen-Zhao; Liu, Yu, E-mail: yuliu@nankai.edu.cn

2014-01-20

Graphical abstract: - Highlights: • Different conformation of β-CD derivatives. • Enthalpy gain. • High binding ability. - Abstract: The molecular binding behaviors of two β-cyclodextrin (β-CD) derivatives bearing 1,2,3-triazole moieties, i.e. mono-6-deoxy-6-{4-(8-oxymethylquinolino)[1,2,3]triazolyl}-β-CD (1) and mono-6-deoxy-6-{4-(8-oxymethylnaphthol)[1,2,3]triazolyl}-β-CD (3), and their analogs without 1,2,3-triazole moieties, i.e. mono-6-deoxy-6-(8-oxymethylquinolino)-β-CD (2) and mono-6-deoxy-6-(8-oxymethylnaphthol)-β-CD (4) toward spherical guests (±)-borneol and (±)-camphor were investigated to elucidate how substituent moiety of host affects the binding abilities by 2D NMR as well as microcalorimetric titrations in aqueous phosphate buffer solution (pH 7.20) at 298.15 K. The binding modes of host–guest interactions obtained from 2D NMR displayed that host CDs without triazole moieties gave better induce-fit efficiency between hosts and guests, leading to stronger binding abilities. Thermodynamically, the inclusion complexation was driven by enthalpy with the stoichiometry of 1:1. Another factor contributed to the enhanced binding abilities was the enthalpy gain with the smaller entropy loss.

Quantification of specific bindings of biomolecules by magnetorelaxometry

Directory of Open Access Journals (Sweden)

Steinhoff Uwe

2008-03-01

Full Text Available Abstract The binding reaction of the biomolecules streptavidin and anti-biotin antibody, both labelled by magnetic nanoparticles (MNP, to biotin coated on agarose beads, was quantified by magnetorelaxometry (MRX. Highly sensitive SQUID-based MRX revealed the immobilization of the MNP caused by the biotin-streptavidin coupling. We found that about 85% of streptavidin-functionalised MNP bound specifically to biotin-agarose beads. On the other hand only 20% of antibiotin-antibody functionalised MNP were specifically bound. Variation of the suspension medium revealed in comparison to phosphate buffer with 0.1% bovine serum albumin a slight change of the binding behaviour in human serum, probably due to the presence of functioning (non heated serum proteins. Furthermore, in human serum an additional non-specific binding occurs, being independent from the serum protein functionality. The presented homogeneous bead based assay is applicable in simple, uncoated vials and it enables the assessment of the binding kinetics in a volume without liquid flow. The estimated association rate constant for the MNP-labelled streptavidin is by about two orders of magnitude smaller than the value reported for free streptavidin. This is probably due to the relatively large size of the magnetic markers which reduces the diffusion of streptavidin. Furthermore, long time non-exponential kinetics were observed and interpreted as agglutination of the agarose beads.

Analyses of uranium in some phosphate commercial products

International Nuclear Information System (INIS)

Kamel, N.H.M.; Sohsah, M.; Mohammad, H.M.; Sadek, M.

2005-01-01

The raw materials used in manufacturing of phosphate fertilizer products were derived from rocks. Rocks contain a remarkable of natural radioactivity. Uranium and phosphorous were originally initiated at the same time of the initiated rocks. The purpose of this research is to investigate solubility of uranium phosphate species at the phosphate fertilizer samples, samples including; raw phosphate material, single super phosphates (SSP) granules and powdered, triple super phosphates (TSP) and phosphogypsum samples were obtained from Abu-Zabal factory in Egypt. Solubility of uranium phosphate species was estimated. It was found that, less than half of the uranium phosphate species are soluble in water. The soluble uranium may be enter into the food chains by plant. Therefore, restriction should be done in order to limit contamination of land and the public

A phosphate-dependent shift in redox state of cerium oxide nanoparticles and its effects on catalytic properties

Energy Technology Data Exchange (ETDEWEB)

Singh, Sanjay; Dosani, Talib; Karakoti, Ajay S.; Kumar, Amit; Seal, Sudipta; Self, William

2011-10-01

Cerium oxide nanoparticles (CeNPs) have shown promise as catalytic antioxidants in cell culture and animal models as both superoxide dismutase and catalase mimetics. The reactivity of the cerium (Ce) atoms at the surface of its oxide particle is critical to such therapeutic properties, yet little is known about the potential for a protein or small molecule corona to form on these materials in vivo. Moreover Ce atoms in these active sites have the potential to interact with small molecule anions, peptides, or sugars when administered in culture or animal models. Several nanomaterials have been shown to alter or aggregate under these conditions, rendering them less useful for biomedical applications. In this work we have studied the change in catalytic properties of CeNPs when exposed to various biologically relevant conditions in vitro. We have found that CeNPs are resistant to broad changes in pH and also not altered by incubation in cell culture medium. However to our surprise phosphate anions significantly altered the characteristics of these nanomaterials and shifted the catalytic behavior due to the binding of phosphate anions to cerium. Given the abundance of phosphate in biological systems in an inorganic form, it is likely that the action of CeNPs as a catalyst may be strongly influenced by the local concentration of phosphate in the cells and/or tissues in which it has been introduced.

[3H]Ouabain binding and Na+, K+-ATPase in resealed human red cell ghosts

International Nuclear Information System (INIS)

Shoemaker, D.G.; Lauf, P.K.

1983-01-01

The interaction of the cardiac glycoside [ 3 H]ouabain with the Na+, K+ pump of resealed human erythrocyte ghosts was investigated. Binding of [ 3 H]ouabain to high intracellular Na+ ghosts was studied in high extracellular Na+ media, a condition determined to produce maximal ouabain binding rates. Simultaneous examination of both the number of ouabain molecules bound per ghost and the corresponding inhibition of the Na+, K+-ATPase revealed that one molecule of [ 3 H]ouabain inhibited one Na+, K+-ATPase complex. Intracellular magnesium or magnesium plus inorganic phosphate produced the lowest ouabain binding rate. Support of ouabain binding by adenosine diphosphate (ADP) was negligible, provided synthesis of adenosine triphosphate (ATP) through the residual adenylate kinase activity was prevented by the adenylate kinase inhibitor Ap5A. Uridine 5'-triphosphate (UTP) alone did not support ouabain binding after inhibition of the endogenous nucleoside diphosphokinase by trypan blue and depletion of residual ATP by the incorporation of hexokinase and glucose. ATP acting solely at the high-affinity binding site of the Na+, K+ pump (Km approximately 1 microM) promoted maximal [ 3 H]ouabain binding rates. Failure of 5'-adenylyl-beta-gamma-imidophosphate (AMP-PNP) to stimulate significantly the rate of ouabain binding suggests that phosphorylation of the pump was required to expose the ouabain receptor

Phosphate Reduction in Emulsified Meat Products: Impact of Phosphate Type and Dosage on Quality Characteristics.

Science.gov (United States)

Glorieux, Seline; Goemaere, Olivier; Steen, Liselot; Fraeye, Ilse

2017-09-01

Phosphate reduction is of important industrial relevance in the manufacturing of emulsified meat products because it may give rise to a healthier product. The effect of seven different phosphate types was tested on the physicochemical and quality characteristics to select the most promising phosphate type for further cooked sausage manufacturing. Next, phosphate mass fraction was gradually reduced. Tetrasodium di- or pyrophosphate (TSPP) and sodium tripolyphosphate (STPP) increased pH, reduced structural properties, resulted in the highest emulsion stability, lowest cooking loss and had little effect on hardness. Based on the viscoelastic properties, a minimum mass fraction of 0.06% TSPP was sufficient to obtain an acceptable quality product. Rheology proved to be a very useful tool to evaluate the quality of meat products, as it gives insight in the structure of the meat product and especially the functional properties of meat proteins. Based on the obtained results, it can be concluded that the current amount of phosphate added to emulsified meat products can be significantly reduced with minimal loss of product quality.

Just-in-time vaccines: Biomineralized calcium phosphate core-immunogen shell nanoparticles induce long-lasting CD8(+) T cell responses in mice.

Science.gov (United States)

Zhou, Weibin; Moguche, Albanus O; Chiu, David; Murali-Krishna, Kaja; Baneyx, François

2014-04-01

Distributed and on-demand vaccine production could be game-changing for infectious disease treatment in the developing world by providing new therapeutic opportunities and breaking the refrigeration "cold chain". Here, we show that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize a biocompatible adjuvant in a single step. The resulting 50 nm calcium phosphate core-immunogen shell particles are comparable to soluble protein in inducing ovalbumin-specific antibody response and class switch recombination in mice. However, single dose vaccination with nanoparticles leads to higher expansion of ovalbumin-specific CD8(+) T cells upon challenge with an influenza virus bearing the ovalbumin-derived SIINFEKL peptide, and these cells produce high levels of IFN-γ. Furthermore, mice exhibit a robust antigen-specific CD8(+) T cell recall response when challenged with virus 8 months post-immunization. These results underscore the promise of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines. This paper reports that a fusion protein between a calcium phosphate binding domain and the model antigen ovalbumin can mineralize into a biocompatible adjuvant in a single step, enabling distributed and on-demand vaccine production and eliminating the need for refrigeration of vaccines. The findings highlight the possibility of immunogen-controlled adjuvant mineralization for just-in-time manufacturing of effective T cell vaccines. Copyright © 2014 Elsevier Inc. All rights reserved.

Competitive binding assay for fructose 2,6-bisphosphate

International Nuclear Information System (INIS)

Thomas, H.; Uyeda, K.

1986-01-01

A new direct assay method for fructose 2,6-bisphosphate has been developed based on competitive binding of labeled and unlabeled fructose 2,6-P 2 to phosphofructokinase. Phosphofructokinase (0.5-1.3 pmol promoter) is incubated with saturating concentrations (5.0-5.5 pmol) of fructose 2,6[2- 32 P]P 2 and samples containing varying concentrations of fructose 2,6-P 2 . The resulting stable binary complex is retained on nitrocellulose filters with a binding efficiency of up to 70%. Standard curves obtained with this assay show strict linearity with varying fructose 2,6-P 2 in the range of 0.5 to 45 pmol, which exceeds the sensitivity of most of the previously described assay methods. Fructose 2,6-P 2 , ATP, and high concentrations of phosphate interfere with this assay. However, the extent of this inhibition is negligible since their tissue contents are one-half to one-tenth that examined. The new assay is simple, direct, rapid, and does not require pretreatment

[Phosphate-solubilizing activity of aerobic methylobacteria].

Science.gov (United States)

Agafonova, N V; Kaparullina, E N; Doronina, N V; Trotsenko, Iu A

2014-01-01

Phosphate-solubilizing activity was found in 14 strains of plant-associated aerobic methylobacteria belonging to the genera Methylophilus, Methylobacillus, Methylovorus, Methylopila, Methylobacterium, Delftia, and Ancyclobacter. The growth of methylobacteria on medium with methanol as the carbon and energy source and insoluble tricalcium phosphate as the phosphorus source was accompanied by a decrease in pH due to the accumulation of up to 7 mM formic acid as a methanol oxidation intermediate and by release of 120-280 μM phosphate ions, which can be used by both bacteria and plants. Phosphate-solubilizing activity is a newly revealed role of methylobacteria in phytosymbiosis.

Isolation and identification of a phosphate solubilising fungus from soil of a phosphate mine in Chaluse, Iran

Directory of Open Access Journals (Sweden)

Raheleh Jamshidi

2016-07-01

Full Text Available Microbial solubilisation of phosphorus from insoluble phosphates is an environmental friendly and cost effective approach in sustainable soil management. Introducing the indigenous microorganisms to soil requires shorter adaptation period and causes fewer ecological distortions than exogenous microorganisms. This study was conducted to isolate and identify the indigenous fungi for phosphate solubilisation in Mazandaran, Iran. A potent phosphate solubilising fungus was isolated from an Iranian phosphate mine and selected for solubilisation of rock phosphate (RP. The identified fungus was characterised by calmodulin-based polymerase chain reaction method as Aspergillus tubingensis SANRU (Sari Agricultural Sciences and Natural Resources University. The phosphate solubilisation ability of the fungal strain was carried out in shake-flask leaching experiments containing various concentrations of RP (1%, 2%, 4%, or 8% w/v. The maximum P solubilisation rate of 347 mg/l was achieved at 1% of RP concentration on day 9. The regression analysis indicated that the P solubilised mainly through acidification. This study shows the possibility of using A. tubingensis SANRU for application in the management of P fertilisation.

Translocation of metal phosphate via the phosphate inorganic transport system of Escherichia coli

NARCIS (Netherlands)

van Veen, H.W; Abee, T.; Kortstee, G.J J; Konings, W.N; Zehnder, A.J B

1994-01-01

P-i transport via the phosphate inorganic transport system (Pit) of Escherichia coil was studied in natural and artificial membranes. P-i uptake via Pit is dependent on the presence of divalent cations, like Mg2+, Ca2+, Co2+, or Mn2+, which form a soluble, neutral metal phosphate (MeHPO(4)) complex.

Co-precipitation of phosphate and iron limits mitochondrial phosphate availability in Saccharomyces cerevisiae lacking the yeast frataxin homologue (YFH1).

Science.gov (United States)

Seguin, Alexandra; Santos, Renata; Pain, Debkumar; Dancis, Andrew; Camadro, Jean-Michel; Lesuisse, Emmanuel

2011-02-25

Saccharomyces cerevisiae cells lacking the yeast frataxin homologue (Δyfh1) accumulate iron in the mitochondria in the form of nanoparticles of ferric phosphate. The phosphate content of Δyfh1 mitochondria was higher than that of wild-type mitochondria, but the proportion of mitochondrial phosphate that was soluble was much lower in Δyfh1 cells. The rates of phosphate and iron uptake in vitro by isolated mitochondria were higher for Δyfh1 than wild-type mitochondria, and a significant proportion of the phosphate and iron rapidly became insoluble in the mitochondrial matrix, suggesting co-precipitation of these species after oxidation of iron by oxygen. Increasing the amount of phosphate in the medium decreased the amount of iron accumulated by Δyfh1 cells and improved their growth in an iron-dependent manner, and this effect was mostly transcriptional. Overexpressing the major mitochondrial phosphate carrier, MIR1, slightly increased the concentration of soluble mitochondrial phosphate and significantly improved various mitochondrial functions (cytochromes, [Fe-S] clusters, and respiration) in Δyfh1 cells. We conclude that in Δyfh1 cells, soluble phosphate is limiting, due to its co-precipitation with iron.

Uranium production from phosphates

International Nuclear Information System (INIS)

Ketzinel, Z.; Folkman, Y.

1979-05-01

According to estimates of the world's uranium consumption, exploitation of most rich sources is expected by the 1980's. Forecasts show that the rate of uranium consumption will increase towards the end of the century. It is therefore desirable to exploit poor sources not yet in use. In the near future, the most reasonable source for developing uranium is phosphate rock. Uranium reserves in phosphates are estimated at a few million tons. Production of uranium from phosphates is as a by-product of phosphate rock processing and phosphoric acid production; it will then be possible to save the costs incurred in crushing and dissolving the rock when calculating uranium production costs. Estimates show that the U.S. wastes about 3,000 tons of uranium per annum in phosphoric acid based fertilisers. Studies have also been carried out in France, Yugoslavia and India. In Israel, during the 1950's, a small plant was operated in Haifa by 'Chemical and Phosphates'. Uranium processes have also been developed by linking with the extraction processes at Arad. Currently there is almost no activity on this subject because there are no large phosphoric acid plants which would enable production to take place on a reasonable scale. Discussions are taking place about the installation of a plant for phosphoric acid production utilising the 'wet process', producing 200 to 250,000 tons P 2 O 5 per annum. It is necessary to combine these facilities with uranium production plant. (author)

Electrical properties of phosphate glasses

International Nuclear Information System (INIS)

Mogus-Milankovic, A; Santic, A; Reis, S T; Day, D E

2009-01-01

Investigation of the electrical properties of phosphate glasses where transition metal oxide such as iron oxide is the network former and network modifier is presented. Phosphate glasses containing iron are electronically conducting glasses where the polaronic conduction is due to the electron hopping from low to high iron valence state. The identification of structural defects caused by ion/polaron migration, the analysis of dipolar states and electrical conductivity in iron phosphate glasses containing various alkali and mixed alkali ions was performed on the basis of the impedance spectroscopy (IS). The changes in electrical conductivity from as-quenched phosphate glass to fully crystallized glass (glass-ceramics) by IS are analyzed. A change in the characteristic features of IS follows the changes in glass and crystallized glass network. Using IS, the contribution of glass matrix, crystallized grains and grain boundary to the total electrical conductivity for iron phosphate glasses was analyzed. It was shown that decrease in conductivity is caused by discontinuities in the conduction pathways as a result of the disruption of crystalline network where two or more crystalline phases are formed. Also, phosphate-based glasses offer a unique range of biomaterials, as they form direct chemical bonding with hard/soft tissue. The surface charges of bioactive glasses are recognized to be the most important factors in determining biological responses. The improved bioactivity of the bioactive glasses as a result of the effects of the surface charges generated by electrical polarization is discussed.

A conserved two-component signal transduction system controls the response to phosphate starvation in Bifidobacterium breve UCC2003.

Science.gov (United States)

Alvarez-Martin, Pablo; Fernández, Matilde; O'Connell-Motherway, Mary; O'Connell, Kerry Joan; Sauvageot, Nicolas; Fitzgerald, Gerald F; MacSharry, John; Zomer, Aldert; van Sinderen, Douwe

2012-08-01

This work reports on the identification and molecular characterization of the two-component regulatory system (2CRS) PhoRP, which controls the response to inorganic phosphate (P(i)) starvation in Bifidobacterium breve UCC2003. The response regulator PhoP was shown to bind to the promoter region of pstSCAB, specifying a predicted P(i) transporter system, as well as that of phoU, which encodes a putative P(i)-responsive regulatory protein. This interaction is assumed to cause transcriptional modulation under conditions of P(i) limitation. Our data suggest that the phoRP genes are subject to positive autoregulation and, together with pstSCAB and presumably phoU, represent the complete regulon controlled by the phoRP-encoded 2CRS in B. breve UCC2003. Determination of the minimal PhoP binding region combined with bioinformatic analysis revealed the probable recognition sequence of PhoP, designated here as the PHO box, which together with phoRP is conserved among many high-GC-content Gram-positive bacteria. The importance of the phoRP 2CRS in the response of B. breve to P(i) starvation conditions was confirmed by analysis of a B. breve phoP insertion mutant which exhibited decreased growth under phosphate-limiting conditions compared to its parent strain UCC2003.

Influence of freezing and thawing on the hydration characteristics, quality, and consumer acceptance of whole muscle beef injected with solutions of salt and phosphate.

Science.gov (United States)

Pietrasik, Z; Janz, J A M

2009-03-01

Effects of salt/phosphate injection level (112% or 125% pump), salt level (0.5% or 1.5% salt), and freezing/thawing on hydration characteristics, quality, and consumer acceptance of beef semitendinosus were investigated. All enhancement treatments decreased shear force by 25-35%, but negatively affected colour. Increased salt concentration yielded lower purge and cooking losses, and higher water holding capacity. The higher injection level reduced water binding properties, however, the loss in functionality with higher water addition was overcome with increased salt content. Freezing and subsequent thawing was generally detrimental to colour and water binding properties and tended to increase shear force. Freezing and subsequent thawing did not affect fluid release in steaks held for 1 day before analysis, but resulted in decreased water retention in samples held for 7 days. Holding vacuum packaged steaks for 7 days generally increased package purge and negatively affected colour parameters, although water binding characteristics were improved. Consumer panel results demonstrated a negative effect on juiciness and tenderness where meat subject to low salt/high injection was frozen then thawed - the low salt level was insufficient to maintain any positive effect of injection treatment. In general, salt/phosphate injection improved product acceptability and increased willingness to purchase.

Hydrogen permeation resistant phosphate coatings

International Nuclear Information System (INIS)

McGuire, J.C.

1979-01-01

A method for reducing hydrogen diffusion through metal wherein the metal is coated with a phosphate-radical-containing, phosphate-glass-forming material on at least one surface thereof. The coating is then heated to at least 350 0 C to form a phosphate glass. This method is especially applicable to nuclear reactors to minimize tritium diffusion. The coating is preferably formed with a solution of phosphoric acid which may also contain compounds such as MnSO 4 , SiO 2 and Na 2 Cr 2 0 7 . (author)

Hydrogen permeation resistant phosphate coatings

International Nuclear Information System (INIS)

McGuire, J.C.

1979-01-01

A method for reducing hydrogen diffusion through metal is described. The metal is coated with a phosphate-radical-containing, phosphate-glass-forming material on at least one surface. The coating is then heated to at least 350 0 C to form a phosphate glass. This method is especially applicable to nuclear reactors to minimize tritium diffusion. The coating is preferably formed with a solution of phosphoric acid which may also contain compounds such as MnSO 4 , SiO 2 and Na 2 Cr 2 O 7 . (author)

Transfer of Some Major and Trace Elements From Phosphate Rock to Super-Phosphate Fertilizers

International Nuclear Information System (INIS)

El-Reefya, H.I.; Bin-Jaz, A.A.; Zaied, M.E.; Badran, H.M.; Badran, H.M.

2014-01-01

This study assesses the transfer of some major and trace elements from phosphate rock (PR) to single (SSP) and triple (TSP) superphosphate fertilizers. Samples from a fertilizer plant and local market were collected and analyzed using inductively coupled plasma spectrometer. Cluster analysis indicated that the inner-relationship among the concentration of the elements in PR, SSP, and TSP are different. Only one element (Mo) has concentration in SSP higher than phosphate rock. The production process of these two types of superphosphate leads to transfer higher portion of Mn, B, Cu, Mo, Sr, and V present in the phosphate rock to SSP than TSP. The potentially hazardous element Cd is also transmitted more to SSP than TSP, and Cr is equally transferred to both types. The mean elemental concentrations normalized to the percentage of P 2 O 5 demonstrate that for most elements they are the higher concentrations in SSP are linked to the phosphate contents

Phosphate vibrations as reporters of DNA hydration

Science.gov (United States)

Corcelli, Steven

The asymmetric phosphate stretch vibrational frequency is extraordinarily sensitive to its local solvent environment. Using density functional theory calculations on the model compound dimethyl phosphate, the asymmetric phosphate stretch vibrational frequency was found to shift linearly with the magnitude of an electric field along the symmetry axis of the PO2 moiety (i.e. the asymmetric phosphate stretch is an excellent linear vibrational Stark effect probe). With this linear relationship established, asymmetric phosphate stretch vibrational frequencies were computed during the course of a molecular dynamics simulation of fully hydrated DNA. Moreover, contributions to shifts in the frequencies from subpopulations of water molecules (e.g. backbone, minor groove, major groove, etc.) were calculated to reveal how phosphate vibrations report the onset of DNA hydration in experiments that vary the relative humidity of non-condensing (dry) DNA samples.

A regenerable potassium and phosphate sorbent system to enhance dialysis efficacy and device portability: an in vitro study.

Science.gov (United States)

Wester, Maarten; Simonis, Frank; Gerritsen, Karin G; Boer, Walther H; Wodzig, Will K; Kooman, Jeroen P; Joles, Jaap A

2013-09-01

Continuous dialysis could provide benefit by constant removal of potassium and phosphate. This study investigates the suitability of specific potassium and phosphate sorbents for incorporation in an extracorporeal device by capacity and regenerability testing. Capacity testing was performed in uraemic plasma. Regenerability was tested for potassium sorbents, with adsorption based on cationic exchange for sodium, with 0.1 M and 1.0 M NaCl. To regenerate phosphate sorbents, with adsorption based on anionic exchange, 0.1 M and 1.0 M NaHCO3 and NaOH were used. Subsequently, sodium polystyrene divinylbenzene sulphonate (RES-A) and iron oxide hydroxide (FeOOH) beads were incorporated in a cartridge for testing in bovine blood using a recirculating blood circuit and a dialysis circuit separated by a high-flux dialyzer (dynamic setup). Preloading was tested to assess whether this could limit calcium and magnesium adsorption. In the batch-binding assays, zirconium phosphate most potently adsorbed potassium (0.44 ± 0.05 mmol/g) and RES-A was the best regenerable potassium sorbent (92.9 ± 5.7% with 0.1 M NaCl). Zirconium oxide hydroxide (ZIR-hydr) most potently adsorbed phosphate (0.23 ± 0.05 mmol/g) and the polymeric amine sevelamer carbonate was the best regenerable sorbent (85.7 ± 5.2% with 0.1 M NaHCO3). In the dynamic setup, a potassium adsorption of 10.72 ± 2.06 mmol in 3 h was achieved using 111 g of RES-A and a phosphate adsorption of 4.73 ± 0.53 mmol in 3 h using 55 g of FeOOH. Calcium and magnesium preloading was shown to reduce the net adsorption in 3 h from 3.57 ± 0.91 to -0.29 ± 1.85 and 1.02 ± 0.05 to -0.31 ± 0.18 mmol, respectively. RES-A and FeOOH are suitable, regenerizable sorbents for potassium and phosphate removal in dialysate regeneration. Use of zirconium carbonate and ZIR-hydr may further increase phosphate adsorption, but may compromise sorbent regenerability. Use of polymeric amines for phosphate adsorption may enhance sorbent

Sonochemical precipitation of amorphous uranium phosphates from trialkyl phosphate solutions and their thermal conversion to UP2O7

Czech Academy of Sciences Publication Activity Database

Doroshenko, I.; Žurková, J.; Moravec, Z.; Bezdička, Petr; Pinkas, J.

2015-01-01

Roč. 26, SEP (2015), s. 157-162 ISSN 1350-4177 Institutional support: RVO:61388980 Keywords : Uranium * Phosphates * Sonochemistry * Nuclear waste * Trimethyl phosphate * Triethyl phosphate Subject RIV: CA - Inorganic Chemistry Impact factor: 4.556, year: 2015

A thermodynamic investigation on the binding of lysozme with sodium dodecyl sulfate

International Nuclear Information System (INIS)

Behbeheni, G.R.; Ramazani, S.; Gonbadi, K.

2013-01-01

The interaction of Sodium Dodecyl Sulfate (SDS) with hen egg lysozyme have been investigated at 298, 303 and 308 K in phosphate buffer at two different pH values (5 and 7), by isothermal titration calorimetry. The calorimetric data analysis allows the measurement of the complete set of thermodynamic parameters. The negative SDS ion binds to positive residues, neutralizes the protein surface charges and leads to precipitation and turbidity of the solution. At low concentrations of SDS, the binding is mainly electrostatic, with some simultaneous interaction of the hydrophobic tail with nearby hydrophobic patches on the lysozyme. The enthalpies of denaturation at pH 7 are 180.47, 198.51 and 216.56 for 298, 303 and 308 K respectively. (author)

Cooperative phosphoinositide and peptide binding by PSD-95/discs large/ZO-1 (PDZ) domain of polychaetoid, Drosophila zonulin.

Science.gov (United States)

Ivarsson, Ylva; Wawrzyniak, Anna Maria; Wuytens, Gunther; Kosloff, Mickey; Vermeiren, Elke; Raport, Marie; Zimmermann, Pascale

2011-12-30

PDZ domains are well known protein-protein interaction modules that, as part of multidomain proteins, assemble molecular complexes. Some PDZ domains have been reported to interact with membrane lipids, in particular phosphatidylinositol phosphates, but few studies have been aimed at elucidating the prevalence or the molecular details of such interactions. We screened 46 Drosophila PDZ domains for phosphoinositide-dependent cellular localization and discovered that the second PDZ domain of polychaetoid (Pyd PDZ2) interacts with phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) at the plasma membrane. Surface plasmon resonance binding experiments with recombinant protein established that Pyd PDZ2 interacts with phosphatidylinositol phosphates with apparent affinities in the micromolar range. Electrostatic interactions involving an extended positively charged surface of Pyd PDZ2 are crucial for the PtdIns(4,5)P(2)-dependent membrane interactions as shown by a combination of three-dimensional modeling, mutagenesis, binding, and localization studies. In vivo localization studies further suggested that both lipid and peptide binding contribute to membrane localization. We identified the transmembrane protein Crumbs as a Pyd PDZ2 ligand and probed the relation between peptide and PtdIns(4,5)P(2) binding. Contrary to the prevalent view on PDZ/peptide/lipid binding, we did not find competition between peptide and lipid ligands. Instead, preloading the protein with the 10-mer Crb3 peptide increased the apparent affinity of Pyd PDZ2 for PtdIns(4,5)P(2) 6-fold. Our results suggest that membrane localization of Pyd PDZ2 may be driven by a combination of peptide and PtdIns(4,5)P(2) binding, which raises the intriguing possibility that the domain may coordinate protein- and phospholipid-mediated signals.

Understanding the Effect of Carbonate Ion on Cisplatin Binding to DNA

Science.gov (United States)

Todd, Ryan C.; Lovejoy, Katherine S.; Lippard, Stephen J.

2008-01-01

The role of carbonate in the binding of cis-diamminedichloroplatinum(II) to DNA was investigated in order to understand the potential involvement of carbonato-cisplatin species in the mechanism of action of platinum anticancer agents. Cisplatin was allowed to react with both double- and single-stranded DNA in carbonate, phosphate, and HEPES buffers, and the products were analyzed by agarose gel electrophoresis and enzymatic digestion/mass spectrometry, respectively. The data from these experiments demonstrate (1) that carbonate, like other biological nucleophiles, forms relatively inert complexes with platinum that inactivate cisplatin, and (2) that the major cisplatin-DNA adduct formed is a bifunctional cross-link. These results are in accord with previous studies of cisplatin-DNA binding and reveal that the presence of carbonate has no consequence on the nature of the resulting adducts. PMID:17465550

Cerebrospinal Fluid Phosphate in Delirium after Hip Fracture

Directory of Open Access Journals (Sweden)

Ane-Victoria Idland

2017-09-01

Full Text Available Aims: Phosphate is essential for neuronal activity. We aimed to investigate whether delirium is associated with altered phosphate concentrations in cerebrospinal fluid (CSF and serum. Methods: Seventy-seven patients with hip fracture were assessed for delirium before and after acute surgery. Prefracture dementia was diagnosed by an expert panel. Phosphate was measured in CSF obtained immediately before spinal anesthesia (n = 77 and in serum (n = 47. CSF from 23 cognitively healthy elderly patients undergoing spinal anesthesia was also analyzed. Results: Hip fracture patients with prevalent delirium had higher CSF phosphate concentrations than those without delirium (median 0.63 vs. 0.55 mmol/L, p = 0.001. In analyses stratified on dementia status, this difference was only significant in patients with dementia. Serum phosphate was ∼1 mmol/L; there was no association between serum phosphate concentration and delirium status. CSF phosphate did not correlate with serum levels. Conclusion: Patients with delirium superimposed on dementia have elevated phosphate levels.

Chloride secretagogues stimulate inositol phosphate formation in shark rectal gland tubules cultured in suspension

International Nuclear Information System (INIS)

Ecay, T.W.; Valentich, J.D.

1991-01-01

Neuroendocrine activation of transepithelial chloride secretion by shark rectal gland cells is associated with increases in cellular cAMP, cGMP, and free calcium concentrations. We report here on the effects of several chloride secretagogues on inositol phosphate formation in cultured rectal gland tubules. Vasoactive intestinal peptide (VIP), atriopeptin (AP), and ionomycin increase the total inositol phosphate levels of cultured tubules, as measured by ion exchange chromatography. Forskolin, a potent chloride secretagogue, has no effect on inositol phosphate formation. The uptake of 3 H-myo-inositol into phospholipids is very slow, preventing the detection of increased levels of inositol trisphosphate. However, significant increases in inositol monophosphate (IP1) and inositol biphosphate (IP2) were measured. The time course of VIP- and AP-stimulated IP1 and IP2 formation is similar to the effects of these agents on the short-circuit current responses of rectal gland monolayer cultures. In addition, aluminum fluoride, an artificial activator of guanine nucleotide-binding proteins, stimulates IP1 and IP2 formation. We conclude that rectal gland cells contain VIP and AP receptors coupled to the activation of phospholipase C. Coupling may be mediated by G-proteins. Receptor-stimulated increases in inositol phospholipid metabolism is one mechanism leading to increased intracellular free calcium concentrations, an important regulatory event in the activation of transepithelial chloride secretion by shark rectal gland epithelial cells

Synthesis, characterization and biodistribution of technetium complexes (99Tc/99mTc) with 2-amino-2-deoxy-D-hexose oximes

International Nuclear Information System (INIS)

Steinmetz, H.J.

1993-05-01

In the present work, the synthesis and isolation of isomeric complexes of technetium ( 99 Tc/ 99m Tc) with the 2-amino-2-deoxy-D-hexoses D-glucose aminoxime, D-galactose aminoxime and D-mannose aminoxime, the characterization of the complexes as 99 Tc compounds, and bio-distribution studies on the analogous 99m Tc complexes have been untertaken. As a first step, the free ligands were synthesized and identified using elemental analysis, infra-red and nuclear magnetic resonance spectroscopy and FAB mass spectroscopy. In the bio-distribution studies on the 99m Tc complexes of D-glucose aminoxime and of D-galactose aminoxime in NMRI mice, significant short-term accumulation of 99m Tc activity in heart muscle could be detected, which may be attributed to a biochemical transport mechanism. Uptake in the lungs and the liver was found, but a more significant uptake was observed in the kidneys, where the complexes were rapidly secreted in proportion to their concentration in the blood plasma. (orig./BBR) [de

Radical-induced dephosphorylation of fructose phosphates in aqueous solution

International Nuclear Information System (INIS)

Zegota, H.; Sonntag, C. von

1981-01-01

Oxygen free N 2 O-saturated aqueous solutions of D-fructose-1-phosphate and D-fructose-6-phosphate were γ-irradiated. Inorganic phosphate and phosphate free sugars (containing four to six carbon atoms) were identified and their G-values measured. D-Fructose-1-phosphate yields (G-values in parentheses) inorganic phosphate (1.6), hexos-2-ulose (0.12), 6-deoxy-2,5-hexodiulose (0.16), tetrulose (0.05) and 3-deoxytetrulose (0.15). D-Fructose-6-phosphate yields inorganic phosphate (1.7), hexos-5-ulose (0.1), 6-deoxy-2,5-hexodiulose (0.36), 3-deoxy-2,5-hexodiulose and 2-deoxyhexos-5-ulose (together 0.18). On treatment with alkaline phosphatase further deoxy sugars were recognized and in fructose-1-phosphate G(6-deoxy-2,5-hexodiulose) was increased to a G-value of 0.4. Dephosphorylation is considered to occur mainly after OH attack at C-5 and C-1 in fructose-1-phosphate and at C-5 and C-6 in fructose-6-phosphate. Reaction mechanisms are discussed. (orig.)

Iron phosphate glass containing simulated fast reactor waste: Characterization and comparison with pristine iron phosphate glass

International Nuclear Information System (INIS)

Joseph, Kitheri; Asuvathraman, R.; Venkata Krishnan, R.; Ravindran, T.R.; Govindaraj, R.; Govindan Kutty, K.V.; Vasudeva Rao, P.R.

2014-01-01

Detailed characterization was carried out on an iron phosphate glass waste form containing 20 wt.% of a simulated nuclear waste. High temperature viscosity measurement was carried out by the rotating spindle method. The Fe 3+ /Fe ratio and structure of this waste loaded iron phosphate glass was investigated using Mössbauer and Raman spectroscopy respectively. Specific heat measurement was carried out in the temperature range of 300–700 K using differential scanning calorimeter. Isoconversional kinetic analysis was employed to understand the crystallization behavior of the waste loaded iron phosphate glass. The glass forming ability and glass stability of the waste loaded glass were also evaluated. All the measured properties of the waste loaded glass were compared with the characteristics of pristine iron phosphate glass

2,2'-Bis(monoacylglycero) PO4 (BMP), but Not 3,1'-BMP, increases membrane curvature stress to enhance α-tocopherol transfer protein binding to membranes.

Science.gov (United States)

Baptist, Matilda; Panagabko, Candace; Nickels, Jonathan D; Katsaras, John; Atkinson, Jeffrey

2015-03-01

Previous work revealed that α-tocopherol transfer protein (α-TTP) co-localizes with bis(monoacylglycero)phosphate (BMP) in late endosomes. BMP is a lipid unique to late endosomes and is believed to induce membrane curvature and support the multivesicular nature of this organelle. We examined the effect of BMP on α-TTP binding to membranes using dual polarization interferometry and vesicle-binding assay. α-TTP binding to membranes is increased by the curvature-inducing lipid BMP. α-TTP binds to membranes with greater affinity when they contain the 2,2'-BMP versus 3,1'-BMP isomers.

Calcium phosphates for biomedical applications

Directory of Open Access Journals (Sweden)

Maria Canillas

2017-05-01

Full Text Available The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies.

Preparation of calcium phosphate paste

International Nuclear Information System (INIS)

Mohd Reusmaazran Yusof; Norzita Yaacob; Idris Besar; Che Seman Mahmood; Rusnah Mustafa

2010-01-01

Calcium phosphate paste were prepared by mixing between calcium sodium potassium phosphate, Ca 2 NaK (PO 4 ) 2 (CSPP) and monocalcium phosphate monohydrate, Ca(H 2 PO 4 ) 2 .H 2 O (MCPM). CSPP were obtained by reaction between calcium hydrogen phosphate (CaHPO 4 ), potassium carbonate (K 2 CO 3 ) and sodium carbonate (Na 2 CO 3 ) in solid state sintering process followed by quenching in air at 1000 degree Celsius. The paste was aging in simulated body fluid (SBF) for 0.5, 1, 3, 6, 12, 24, 48 hrs, 3, 7 and 14 days. The morphological investigation indicated the formation of apatite crystal were first growth after 24 hours. The obvious growth of apatite crystal was shown at 3 days. The obvious growth of apatite crystal was shown in 7 and 14 days indicated the prediction of paste would have rapid reaction with bone after implantation. (author)

Calcium phosphates for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

2017-07-01

The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

Conditions promoting and restraining agronomic effectiveness of water-insoluble phosphate sources, in particular phosphate rock (PR): I. Indices of phosphate rock use opportunity (PRUOIS) and of phosphate rock suitability for direct use (PRSIDU)

International Nuclear Information System (INIS)

Borlan, Z.; Gavriluta, I.; Soare, M.; Stefanescu, D.; Alexandrescu, A.

2002-01-01

Several issues of phosphate rock (PR) use are discussed in this paper. Maize for green fodder (Zea mays L) and ryegrass (Lolium multiflorum Lam.) were grown in 7 kg of dry soil and in small pots of 1.25 kg dry soil capacity, respectively, on several base unsaturated soils belonging to Hapludoll and Hapludalf soil groups. The amount of phosphate rock (PR) to apply was based on experimental data considering soil adsorbed acidity (Ah), humus content (H 2 ), cation exchange capacity (T), sum of exchangeable bases (SEB) and mobile (easily soluble) phosphate content (P A L) in the soil. The factors were combined in a rock phosphate use, opportunity index of the soil (PRUOIS): PRUOIS=(A h *H 2 *100)/SEB*10 0.0245*P AL Rock phosphate suitability for direct use was evaluated by means of the rate of PR-P dissolution (PRPRS) in a 0.6% ammonium heptamolybdate in 0.01M calcium chloride solution (ppm P) and by carbonate content (%CaCO 3 ) in PR. Both of these parameters combined provided a phosphate rock suitability index for direct use (PRSIDU): PRSIDU [ppmP/min]=PRPRS*(1-0.03*CaCO 3 ) Water insoluble P sources studied were PR from Kola-Russia, Morocco, Kneifiss-Siria, El Hassa-Jordan, Gafsa- Tunisia, North-Carolina (USA), and Arad-Israel. All PRs were compared with TSP applied at the same rate of P. Neither PRUOIS or PRSIDU considered separately could satisfactorily explain the variance of PR efficiency. An index obtained by multiplicative combination of PRUOIS x PRSIDU did correlate significantly with indices on the agronomic efficiency of PR. (author)

Impaired Phosphate Tolerance Revealed With an Acute Oral Challenge.

Science.gov (United States)

Turner, Mandy E; White, Christine A; Hopman, Wilma M; Ward, Emilie C; Jeronimo, Paul S; Adams, Michael A; Holden, Rachel M

2018-01-01

Elevated serum phosphate is consistently linked with cardiovascular disease (CVD) events and mortality in the setting of normal and impaired kidney function. However, serum phosphate does not often exceed the upper limit of normal until glomerular filtration rate (GFR) falls below 30 mL/min/m 2 . It was hypothesized that the response to an oral, bioavailable phosphate load will unmask impaired phosphate tolerance, a maladaptation not revealed by baseline serum phosphate concentrations. In this study, rats with varying kidney function as well as normo-phosphatemic human subjects, with inulin-measured GFR (13.2 to 128.3mL/min), received an oral phosphate load. Hormonal and urinary responses were evaluated over 2 hours. Results revealed that the more rapid elevation of serum phosphate was associated with subjects and rats with higher levels of kidney function, greater responsiveness to acute changes in parathyroid hormone (PTH), and significantly more urinary phosphate at 2 hours. In humans, increases in urinary phosphate to creatinine ratio did not correlate with baseline serum phosphate concentrations but did correlate strongly to early increase of serum phosphate. The blunted rise in serum phosphate in rats with CKD was not the result of altered absorption. This result suggests acute tissue deposition may be altered in the setting of kidney function impairment. Early recognition of impaired phosphate tolerance could translate to important interventions, such as dietary phosphate restriction or phosphate binders, being initiated at much higher levels of kidney function than is current practice. © 2017 American Society for Bone and Mineral Research. © 2017 American Society for Bone and Mineral Research.

Phosphate Reduction in Emulsifi ed Meat Products: Impact of Phosphate Type and Dosage on Quality Characteristics

Directory of Open Access Journals (Sweden)

Seline Glorieux

2017-01-01

Full Text Available Phosphate reduction is of important industrial relevance in the manufacturing of emulsifi ed meat products because it may give rise to a healthier product. The eff ect of seven diff erent phosphate types was tested on the physicochemical and quality characteristics to select the most promising phosphate type for further cooked sausage manufacturing. Next, phosphate mass fraction was gradually reduced. Tetrasodium di- or pyrophosphate (TSPP and sodium tripolyphosphate (STPP increased pH, reduced structural properties, resulted in the highest emulsion stability, lowest cooking loss and had litt le eff ect on hardness. Based on the viscoelastic properties, a minimum mass fraction of 0.06 % TSPP was suffi cient to obtain an acceptable quality product. Rheology proved to be a very useful tool to evaluate the quality of meat products, as it gives insight in the structure of the meat product and especially the functional properties of meat proteins. Based on the obtained results, it can be concluded that the current amount of phosphate added to emulsifi ed meat products can be signifi cantly reduced with minimal loss of product quality.

Transport of the Glucosamine-Derived Browning Product Fructosazine (Polyhydroxyalkylpyrazine) Across the Human Intestinal Caco-2 Cell Monolayer: Role of the Hexose Transporters.

Science.gov (United States)

Bhattacherjee, Abhishek; Hrynets, Yuliya; Betti, Mirko

2017-06-14

The transport mechanism of fructosazine, a glucosamine self-condensation product, was investigated using a Caco-2 cell model. Fructosazine transport was assessed by measuring the bidirectional permeability coefficient across Caco-2 cells. The mechanism of transport was evaluated using phlorizin, an inhibitor of sodium-dependent glucose cotransporters (SGLT) 1 and 2, phloretin and quercetin, inhibitors of glucose transporters (GLUT) 1 and 2, transcytosis inhibitor wortmannin, and gap junction disruptor cytochalasin D. The role of hexose transporters was further studied using downregulated or overexpressed cell lines. The apparent permeability (P a,b ) of fructosazine was 1.30 ± 0.02 × 10 -6 cm/s. No significant (p > 0.05) effect was observed in fructosazine transport by adding wortmannin and cytochalasin D. The presence of phlorizin, phloretin, and quercetin decreased fructosazine transport. The downregulated GLUT cells line was unable to transport fructosazine. In human intestinal epithelial Caco-2 cells, GLUT1 or GLUT2 and SGLT are mainly responsible for fructosazine transport.

Exploring the potential of lactic acid production from lignocellulosic hydrolysates with various ratios of hexose versus pentose by Bacillus coagulans IPE22.

Science.gov (United States)

Wang, Yujue; Cao, Weifeng; Luo, Jianquan; Wan, Yinhua

2018-08-01

The aim of this study was to investigate the feasibility of utilizing different lignocellulosic hydrolysates with various hexose versus pentose (H:P) ratios to produce lactic acid (LA) from Bacillus coagulans IPE22 by fermentations with single and mixed sugar. In single sugar utilization, glucose tended to promote LA production, and xylose preferred to enhance cell growth. In mixed sugar utilization, glucose and pentose were consumed simultaneously when glucose concentration was lower than 20 g/L, and almost the same concentration of LA (50 g/L) was obtained regardless of the differences of H:P values. Finally, LA production from corn cob hydrolysates (CCH) contained 60 g/L mixed sugar verified the mechanisms found in the fermentations with simulated sugar mixture. Comparing with single glucose utilization, CCH utilization was faster and the yield of LA was not significantly affected. Therefore, the great potential of producing LA with lignocellulosic materials by B. coagulans was proved. Copyright © 2018. Published by Elsevier Ltd.

Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

International Nuclear Information System (INIS)

Cao Feng; Li Dongxu

2010-01-01

Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe 3+ , which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

Energy Technology Data Exchange (ETDEWEB)

Cao Feng; Li Dongxu, E-mail: dongxuli@njut.edu.c [College of Materials Science and Engineering, Nanjing University of Technology, Jiangsu Nanjing 210009 (China)

2010-03-15

Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe{sup 3+}, which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

The Effect of Moderate Dietary Protein and Phosphate Restriction on Calcium-Phosphate Homeostasis in Healthy Older Cats.

Science.gov (United States)

Geddes, R F; Biourge, V; Chang, Y; Syme, H M; Elliott, J

2016-09-01

Dietary phosphate and protein restriction decreases plasma PTH and FGF-23 concentrations and improves survival time in azotemic cats, but has not been examined in cats that are not azotemic. Feeding a moderately protein- and phosphate-restricted diet decreases PTH and FGF-23 in healthy older cats and thereby slows progression to azotemic CKD. A total of 54 healthy, client-owned cats (≥ 9 years). Prospective double-blinded randomized placebo-controlled trial. Cats were assigned to test diet (protein 76 g/Mcal and phosphate 1.6 g/Mcal) or control diet (protein 86 g/Mcal and phosphate 2.6 g/Mcal) and monitored for 18 months. Changes in variables over time and effect of diet were assessed by linear mixed models. A total of 26 cats ate test diet and 28 cats ate control diet. There was a significant effect of diet on urinary fractional excretion of phosphate (P = 0.045), plasma PTH (P = 0.005), and ionized calcium concentrations (P = 0.018), but not plasma phosphate, FGF-23, or creatinine concentrations. Plasma PTH concentrations did not significantly change in cats fed the test diet (P = 0.62) but increased over time in cats fed the control diet (P = 0.001). There was no significant treatment effect of the test diet on development of azotemic CKD (3 of 26 (12%) test versus 3 of 28 (11%) control, odds ratio 1.09 (95% CI 0.13-8.94), P = 0.92). Feeding a moderately protein- and phosphate-restricted diet has effects on calcium-phosphate homeostasis in healthy older cats and is well tolerated. This might have an impact on renal function and could be useful in early chronic kidney disease. Copyright © 2016 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Isolation of phosphatase-producing phosphate solubilizing bacteria from Loriya hot spring: Investigation of phosphate solubilizing in the presence of different parameters

Directory of Open Access Journals (Sweden)

Maryam Parhamfar

2014-04-01

Full Text Available Introduction: Biofertilizers are the microorganisms that can convert useless nutrient to usable compounds. Unlike fertilizer, cost of biofertilizer production is low and doesn’t produce ecosystem pollution. Phosphate fertilizers can be replaced by phosphate biofertilizer to produce improvement. So, it is necessary to screen the climate-compatible phosphate solubilizing bacteria. Materials and methods: In this project samples were picked up from Loriya hot spring, which are located in Jiroft. Samples were incubated in PKV medium for 3 days. Screening of phosphate solubilizing bacteria was performed on the specific media, based on clear area diameter. The best bacterium was identified based on 16s rDNA gene. Phosphate solubilizing activity of this strain was considered in different carbon, nitrogen, phosphate and pH sources. Results: Sequence alignment and phylogenetic tree results show that B. sp. LOR033 is closely related to Bacillus licheniformis, with 97% homology. In addition, results show that maximum enzyme production was performed after 2 days that incubation pH was decreased simultaneously when the time was increased. Carbon sources investigation show that glucose is the most appropriate in enzyme production and phosphate releasing. Furthermore, results show that the optimum initial pH for phytase production was pH5.0. Different phosphate sources show that tricalcium phosphate has the suitable effect on enzyme activity in three days of incubation. Discussion and conclusion: Phosphatase enzyme production capacity, growth in acidic pH and phosphate solubilizing potential in different salt and phosphate sources show that this strain has considerable importance as biofertilizers.

Aqueous phosphate removal using nanoscale zero-valent iron

International Nuclear Information System (INIS)

Almeelbi, Talal; Bezbaruah, Achintya

2012-01-01

Nanoscale zero-valent iron (NZVI) particles have been used for the remediation of a wide variety of contaminants. NZVI particles have high reactivity because of high reactive surface area. In this study, NZVI slurry was successfully used for phosphate removal and recovery. Batch studies conducted using different concentrations of phosphate (1, 5, and 10 mg PO 4 3− -P/L with 400 mg NZVI/L) removed ∼96 to 100 % phosphate in 30 min. Efficacy of the NZVI in phosphate removal was found to 13.9 times higher than micro-ZVI (MZVI) particles with same NZVI and MZVI surface area concentrations used in batch reactors. Ionic strength, sulfate, nitrate, and humic substances present in the water affected in phosphate removal by NZVI but they may not have any practical significance in phosphate removal in the field. Phosphate recovery batch study indicated that better recovery is achieved at higher pH and it decreased with lowering of the pH of the aqueous solution. Maximum phosphate recovery of ∼78 % was achieved in 30 min at pH 12. The successful rapid removal of phosphate by NZVI from aqueous solution is expected to have great ramification for cleaning up nutrient rich waters.

Research and engineering assessment of biological solubilization of phosphate

Energy Technology Data Exchange (ETDEWEB)

Rogers, R.D.; McIlwain, M.E.; Losinski, S.J.; Taylor, D.D.

1993-03-01

This research and engineering assessment examined a microbial phosphate solubilization process as a method of recovering phosphate from phosphorus containing ore compared to the existing wet acid and electric arc methods. A total of 860 microbial isolates, collected from a range of natural environments were tested for their ability to solubilize phosphate from rock phosphate. A bacterium (Pseudomonas cepacia) was selected for extensive characterization and evaluation of the mechanism of phosphate solubilization and of process engineering parameters necessary to recover phosphate from rock phosphate. These studies found that concentration of hydrogen ion and production of organic acids arising from oxidation of the carbon source facilitated microbial solubilization of both pure chemical insoluble phosphate compounds and phosphate rock. Genetic studies found that phosphate solubilization was linked to an enzyme system (glucose dehydrogenase). Process-related studies found that a critical solids density of 1% by weight (ore to liquid) was necessary for optimal solubilization. An engineering analysis evaluated the cost and energy requirements for a 2 million ton per year sized plant, whose size was selected to be comparable to existing wet acid plants.

21 CFR 582.1781 - Sodium aluminum phosphate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium aluminum phosphate. 582.1781 Section 582.1781 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Additives § 582.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b) Conditions of...

21 CFR 182.1781 - Sodium aluminum phosphate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium aluminum phosphate. 182.1781 Section 182.1781 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b...

Creatine-creatine phosphate shuttle modeled as two-compartment system at different levels of creatine kinase activity

DEFF Research Database (Denmark)

Fedosov, Sergey

1994-01-01

In order to characterize ADP-ATP and creatine-creatine phosphate (Cr-CrP) shuttles a minimal mathematical model with two compartments and cyclic turnover of matter was designed. The 'mitochondrial' compartment contained 'ATP-synthase' and 'mitochondrial ereatine kinase' (mitCK). The 'cytoplasmic......' compartment consisted of 'ATPase', 'cytoplasmic creatine kinase' (cytCK) and an 'ADP-binding structure'. The exchange of metabolites between these compartments was limited. Different levels of cytCK and mitCK expression as welt as different exchange rate constants between the compartments were assigned...

Removal mechanism of phosphate from aqueous solution by fly ash.

Science.gov (United States)

Lu, S G; Bai, S Q; Zhu, L; Shan, H D

2009-01-15

This work studied the effectiveness of fly ash in removing phosphate from aqueous solution and its related removal mechanism. The adsorption and precipitation of phosphate by fly ash were investigated separately in order to evaluate their role in the removal of phosphate. Results showed that the removal of phosphate by fly ash was rapid. The removal percentage of phosphate in the first 5min reached 68-96% of the maximum removal of phosphate by fly ash. The removal processes of phosphate by fly ash included a fast and large removal representing precipitation, then a slower and longer removal due to adsorption. The adsorption of phosphate on fly ash could be described well by Freundlich isotherm equation. The pH and Ca2+ concentration of fly ash suspension were decreased with the addition of phosphate, which suggests that calcium phosphate precipitation is a major mechanism of the phosphate removal. Comparison of the relative contribution of the adsorption and precipitation to the total removal of phosphate by fly ash showed that the adsorption accounted for 30-34% of the total removal of phosphate, depending on the content of CaO in fly ash. XRD patterns of the fly ash before and after phosphate adsorption revealed that phosphate salt (CaHPO4 x 2H2O) was formed in the adsorption process. Therefore, the removal of phosphate by fly ash can be attributed to the formation of phosphate precipitation as a brushite and the adsorption on hydroxylated oxides. The results suggested that the use of fly ash could be a promising solution to the removal of phosphate in the wastewater treatment and pollution control.

Isolation and screening phosphate solubilizers from composts as biofertilizer

International Nuclear Information System (INIS)

Phua Choo Kwai Hoe; Khairuddin Abdul Rahim; Latiffah Norddin; Abdul Razak Ruslan

2006-01-01

Phosphate solubilizers are miroorganisms that able to solubilize insoluble inorganic phosphate compounds or hydrolyze organic phosphate to inorganic P. Therefore make the P to be available for plant and consequently enhance plant growth and yield. Recently, phosphate solubilizing microorganisms has been shown to play an important role in the biofertilizer industry. Fifty-one bacterial were isolated from eleven composts. Most of the phosphate solubilizers were isolated from natural farming composted compost and normal composting compost. This shows that both of these composts are more suitable to use for phosphate solubilizer isolation compare commercial composts. Fourteen of the isolates were found to be phosphate solubilizers. These isolates produced a clear zone on the phosphate agar plates, showing their potential as biofertilizer. AP3 was significantly produced the largest clear zone compared with other isolates. This indicates that isolate AP 3 could be a good phosphate solubilizer. Thus, their effectiveness in the greenhouse and field should be evaluated. (Author)

Uranium endowments in phosphate rock

Energy Technology Data Exchange (ETDEWEB)

Ulrich, Andrea E., E-mail: andrea.ulrich@env.ethz.ch [Institute for Environmental Decisions (IED), Natural and Social Science Interface, ETH Zurich Universitässtrasse 22, 8092 Zurich (Switzerland); Institute for Agricultural Sciences, Plant Nutrition, ETH Zurich, Eschikon 33, 8315 Lindau (Switzerland); Schnug, Ewald, E-mail: e.schnug@tu-braunschweig.de [Department of Life Sciences, Technical University of Braunschweig, Pockelsstraße 14, D-38106 Braunschweig (Germany); Prasser, Horst-Michael, E-mail: prasser@lke.mavt.ethz.ch [Institute of Energy Technology, Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8092 Zurich (Switzerland); Frossard, Emmanuel, E-mail: emmanuel.frossard@usys.ethz.ch [Institute for Agricultural Sciences, Plant Nutrition, ETH Zurich, Eschikon 33, 8315 Lindau (Switzerland)

2014-04-01

This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers. - Highlights: • We identify components that underlie the recovery of uranium from phosphate rock. • We estimate that 11,000 tU may have been recoverable from phosphoric acid in 2010. • Recovery is a resource conservation and environmental pollution control strategy. • To ensure investment in recovery technology, profitability needs to be secured.

Uranium endowments in phosphate rock

International Nuclear Information System (INIS)

Ulrich, Andrea E.; Schnug, Ewald; Prasser, Horst-Michael; Frossard, Emmanuel

2014-01-01

This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers. - Highlights: • We identify components that underlie the recovery of uranium from phosphate rock. • We estimate that 11,000 tU may have been recoverable from phosphoric acid in 2010. • Recovery is a resource conservation and environmental pollution control strategy. • To ensure investment in recovery technology, profitability needs to be secured

Phosphate Salts

Science.gov (United States)

... body. They are involved in cell structure, energy transport and storage, vitamin function, and numerous other processes ... Phosphate-containing foods and beverages include cola, wine, beer, whole grain cereals, nuts, dairy products and some ...

Synthesis of amorphous acid iron phosphate nanoparticles

International Nuclear Information System (INIS)

Palacios, E.; Leret, P.; Fernández, J. F.; Aza, A. H. De; Rodríguez, M. A.

2012-01-01

A simple method to precipitate nanoparticles of iron phosphate with acid character has been developed in which the control of pH allows to obtain amorphous nanoparticles. The acid aging of the precipitated amorphous nanoparticles favored the P–O bond strength that contributes to the surface reordering, the surface roughness and the increase of the phosphate acid character. The thermal behavior of the acid iron phosphate nanoparticles has been also studied and the phosphate polymerization at 400 °C produces strong compacts of amorphous nanoparticles with interconnected porosity.

Control of plant phosphate homeostasis by inositol pyrophosphates and the SPX domain.

Science.gov (United States)

Jung, Ji-Yul; Ried, Martina K; Hothorn, Michael; Poirier, Yves

2018-02-01

Proteins containing a SPX domain are involved in phosphate (Pi) homeostasis, including Pi transport and adaptation to Pi deficiency. The SPX domain harbors a basic surface binding Pi at low affinity and inositol pyrophosphates (PP-InsPs) at high affinity. Genetic and biochemical studies revealed that PP-InsPs serve as ligands for the SPX domain. Residues in the PHO1 SPX domain involved in PP-InsPs binding are critical for its Pi export activity, and the interaction between SPX proteins and the PHR1 transcription factor, which results in PHR1 inactivation, is promoted by PP-InsPs. Changes in PP-InsPs levels in response to Pi deficiency may thus contribute to the adaptation of plants to stress via the modulation of the activity of SPX-containing proteins and their interactors. Modulating PP-InsP levels or the affinity/specificity of the SPX domain for PP-InsP could potentially be used to engineer crops to maintain high yield under reduced Pi fertilizer input. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of tricyclic antidepressants on transmitter-stimulated inositol phosphate production in rat brain cortex in vitro

International Nuclear Information System (INIS)

Nomura, S.; Enna, S.J.

1986-01-01

Tricyclic antidepressants (TCAs) have anticholinergic and α-adrenergic blocking properties. The present study was undertaken to examine the effects of amitriptyline, imipramine, and desipramine on inositol phosphate accumulation, a brain second messenger system associated with cholinergic and adrenergic receptors. Whereas the TCAs were 28 to 400-fold weaker than atropine as inhibitors of 3 H-QNB binding to brain cholinergic receptors, they were 600 to 2000-fold less active than atropine as inhibitors of carbachol-stimulated IP accumulation in brain. In contrast, the relative potencies of the TCAs and prazosin to inhibit norepinephrine-stimulated IP accumulation and 3 H-prazosin binding appeared to be similar in the two assays. The results suggest pharmacological differences between the cholinergic receptors labeled in the ONB binding assay and those mediating the IP response, whereas the α 1 -adrenergic receptors appear to be similar in the two systems. Since atropine is considered a nonselective muscarinic antagonist, it is possible that the TCAs may differentiate between cholinergic receptor subtypes, which may be an important component of their clinical response

Enzymes in biogenesis of plant cell wall polysaccharides. Enzyme characterization using tracer techniques

International Nuclear Information System (INIS)

Dickinson, D.B.

1975-01-01

Enzymes and metabolic pathways, by which starch and cell wall polysaccharides are formed, were investigated in order to learn how these processes are regulated and to identify the enzymatic regulatory mechanisms involved. Germinating lily pollen was used for studies of cell wall formation, and pollen and maize endosperm for studies of starch biosynthesis. Hexokinase being the first step in conversion of hexoses to starch, wall polysaccharides and respiratory substrates, maize endosperm enzyme was assayed by its conversion of 14 C-hexose to 14 C-hexose-6-P, and rapid separation of the two labelled compounds on anion-exchange paper. This enzyme did not appear to be under tight regulation by feed-back inhibition or activation, nor to be severely inhibited by glucose-6-P or activated by citrate. ADP-glucose pyrophosphorylase and other pyrophosphorylases were assayed radiochemically with 14 C-glucose-1-P (forward direction) or 32-PPsub(i) (reverse direction). They showed that the maize endosperm enzyme was activated by the glycolytic intermediates fructose-6-P and 3-phosphoglycerate, and that low levels of the enzyme were present in the high sucrose-low starch mutant named shrunken-2. Under optimal in-vitro assay conditions, the pollen enzyme reacted four times faster than the observed in-vivo rate of starch accumulation. Biogenesis of plant cell wall polysaccharides requires the conversion of hexose phosphates to various sugar nucleotides and utilization of the latter by the appropriate polysaccharide synthetases. Lily pollen possesses a β-1,3-glucan synthetase which is activated up to six-fold by β-linked oligosaccharides. Hence, the in-vivo activity of this enzyme may be modulated by such effector molecules

Are Polyphosphates or Phosphate Esters Prebiotic Reagents?

Science.gov (United States)

Keefe, Anthony D.; Miller, Stanley L.

1995-01-01

It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in nature, the efficiency of the volcanic synthesis of P4O10, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources.

21 CFR 582.5697 - Riboflavin-5-phosphate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Riboflavin-5-phosphate. 582.5697 Section 582.5697 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5697 Riboflavin-5-phosphate. (a) Product. Riboflavin-5-phosphate. (b) Conditions of use...

Resonance energy transfer study on the proximity relationship between the GTP binding site and the rifampicin binding site of Escherichia coli RNA polymerase

International Nuclear Information System (INIS)

Kumar, K.P.; Chatterji, D.

1990-01-01

Terbium(III) upon complexation with guanosine 5'-triphosphate showed remarkable enhancement of fluorescence emission at 488 and 545 nm when excited at 295 nm. Analysis of the binding data yielded a value for the mean K d between Tb(III) and GTP of 0.2 μM, with three binding sites for TB(III) on GTP. 31 P and 1 H NMR measurements revealed that Tb(III) mainly binds the phosphate moiety of GTP. Fluorescence titration of the emission signals of the TbGTP complex with varying concentrations of Escherichia coli RNA polymerase resulted in a K d values of 4 μM between the TbGTP and the enzyme. It was observed that TbGTP can be incorporated in the place of GTP during E. coli RNA polymerase catalyzed abortive synthesis of dinucleotide tetraphosphate at T7A2 promoter. Both the substrate TbGTP and the inhibitor of the initiation of transcription rifampicin bind to the β-subunit of E. coli RNA polymerase. This allows the measurement of the fluorescence excited-state energy transfer from the donor TbGTP-RNA polymerase to the acceptor rifampicin. Both emission bands of Tb(III) overlap with the rifampicin absorption, and the distances at 50% efficiency of energy transfer were calculated to be 28 and 24 angstrom for the 488- and 545-nm emission bands, respectively. The distance between the substrate binding site and the rifampicin binding site on the β-subunit of E. coli RNA polymerase was measured to be around 30 angstrom. This suggest that the nature of inhibition of transcription by rifampicin is essentially noncompetitive with the substrate

Mineral phosphate solubilizing bacterial community in agro-ecosystem

African Journals Online (AJOL)

STORAGESEVER

2009-12-15

Dec 15, 2009 ... patterns. Four insoluble phosphate sources; purulia rock phosphate (PRP), mussourie rock phosphate. (MRP) ... community composition analysis (Garland, 1996a) and ..... the threshold level that enabled only a few species to.

Structure of 1-deoxy-d-xylulose 5-phosphate reductoisomerase in a quaternary complex with a magnesium ion, NADPH and the antimalarial drug fosmidomycin

International Nuclear Information System (INIS)

Yajima, Shunsuke; Hara, Kodai; Iino, Daisuke; Sasaki, Yasuyuki; Kuzuyama, Tomohisa; Ohsawa, Kanju; Seto, Haruo

2007-01-01

The crystal structure of 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) from Escherichia coli complexed with Mg 2+ , NADPH and fosmidomycin was determined at 2.2 Å resolution. The structure showed a well defined loop conformation at the active site of DXR. The crystal structure of 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) from Escherichia coli complexed with Mg 2+ , NADPH and fosmidomycin was solved at 2.2 Å resolution. DXR is the key enzyme in the 2-C-methyl-d-erythritol 4-phosphate pathway and is an effective target of antimalarial drugs such as fosmidomycin. In the crystal structure, electron density for the flexible loop covering the active site was clearly observed, indicating the well ordered conformation of DXR upon substrate binding. On the other hand, no electron density was observed for the nicotinamide-ribose portion of NADPH and the position of Asp149 anchoring Mg 2+ was shifted by NADPH in the active site

Hydroformylation of propene and 1-hexene catalysed by a alpha-zirconium phosphate supported rhodium-phosphine complex

DEFF Research Database (Denmark)

Karlsson, Magnus; Andersson, C; Hjortkjær, Jes

2001-01-01

The reaction of the amphiphilic ligand {4-[bis(diethylaminoethyl)aminomethyl]diphenyl}phosphine with alpha -zirconium phosphate, of intermediate surface area (24m(2) g(-1)), provided a phosphine functionalised support in which electrostatic interaction between ammonium groups on the ligand and de......-protonated surface hydroxyl groups on the support provided the binding force. The X-ray powder diffractogram of the material showed that the binding lowers the crystallinity of the carrier and that the ligand is not intercalated but bound at the outer surface and at the entrances to the interlamellar space. Reaction...... of the phosphine functionalised support with Rh(CO)(2)(acac) led to CO-phosphine exchange and formation of an immobilised complex of the composition LRh(CO)(acac) (L = surface bound phosphine). When applied as catalyst in continuous gas-phase hydroformylation of propene and in liquid phase hydroformylation of 1...

The role of water in the thermodynamics of drug binding to cyclodextrin

Energy Technology Data Exchange (ETDEWEB)

Todorova, Niya A. [Center for Advanced Research in Biotechnology, National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, MD 20850 (United States); Schwarz, Frederick P. [Center for Advanced Research in Biotechnology, National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, MD 20850 (United States)]. E-mail: fred@carb.nist.gov

2007-07-15

The thermodynamic parameters, {delta}{sub B} G {sup 0}, {delta}{sub B} H {sup 0}, {delta}{sub B} S {sup 0}, and {delta}{sub B} C {sub p}, of the drugs flurbiprofen (FLP), nabumetone (NAB), and naproxen (NPX) binding to {beta}-cyclodextrin ({beta}CD) and to {gamma}-cyclodextrin ({gamma}CD) in 0.10 M sodium phosphate buffer were determined from isothermal titration calorimetry (ITC) measurements over the temperature range from 293.15 K to 313.15 K. The heat capacity changes for the binding reactions ranged from -(362 {+-} 48) J . mol{sup -1} . K{sup -1} for FLP and -(238 {+-} 90) J . mol{sup -1} . K{sup -1} for NAB binding in the {beta}CD cavity to 0 for FLP and -(25.1 {+-} 9.2) J . mol{sup -1} . K{sup -1} for NPX binding in the larger {gamma}CD cavity, implying that the structure of water is reorganized in the {beta}CD binding reactions but not reorganized in the {gamma}CD binding reactions. Comparison of the fluorescence enhancements of FLP and NAB upon transferring from the aqueous buffer to isopropanol with the maximum fluorescence enhancements observed for their {beta}CD binding reactions indicated that some localized water was retained in the FLP-{beta}CD complex and almost none in the NAB-{beta}CD complex. No fluorescence change occurs with drug binding in the larger {gamma}CD cavity, indicating the retention of the bulk water environment in the drug-{gamma}CD complex. Since the specific drug binding interactions are essentially the same for {beta}CD and {gamma}CD, these differences in the retention of bulk water may account for the enthalpically driven nature of the {beta}CD binding reactions and the entropically driven nature of the {gamma}CD binding reactions.

[Phosphate solubilization of Aureobasidium pullulan F4 and its mechanism].

Science.gov (United States)

Wang, Dan; Zhan, Jing; Sun, Qing-Ye

2014-07-01

The Aureobasidium pullulans F4 was isolated from the rhizosphere of Hippochaete ramosissimum in Tongguanshan mine wasteland in Tongling City, Anhui Province. Liquid culture was conducted with four kinds of phosphorus sources, calcium phosphate, aluminum phosphate, ferric phosphate and rock phosphate to determine the pH, dissolved phosphorus, phosphorus in the bacteria and organic acid in the solution. The results showed that the phosphate solubilization by A. pullulans F4 varied with phosphorus sources, which decreased in order of aluminum phosphate > ferric phosphate, calcium phosphate > rock phosphate. The amounts of dissolved phosphorus in the different treatments were all higher than 200 mg x L(-1). The pH of the medium dropped immediately in 48 h, and the aluminum phosphate and ferric phosphate treatments showed a greater decrease in pH than the calcium phosphate and rock phosphate treatments. The organic acid synthesized by A. pullulans F4 included oxalic acid, citric acid and tartaric acid, and oxalic acid, among which oxalic acid was the dominated component. The phosphate dissolving capacity of A. pullulans F4 showed no significant correlation with organic acid, but significantly correlated with the pH. The available phosphorus was significantly improved with the combined application of A. pullulans F4 and glucose, suggesting A. pullulans F4 was a potent candidate for remediation of copper mine wastelands.

Effect of lysine to alanine mutations on the phosphate activation and BPTES inhibition of glutaminase.

Science.gov (United States)

McDonald, Charles J; Acheff, Eric; Kennedy, Ryan; Taylor, Lynn; Curthoys, Norman P

2015-09-01

The GLS1 gene encodes a mitochondrial glutaminase that is highly expressed in brain, kidney, small intestine and many transformed cells. Recent studies have identified multiple lysine residues in glutaminase that are sites of N-acetylation. Interestingly, these sites are located within either a loop segment that regulates access of glutamine to the active site or the dimer:dimer interface that participates in the phosphate-dependent oligomerization and activation of the enzyme. These two segments also contain the binding sites for bis-2[5-phenylacetamido-1,2,4-thiadiazol-2-yl]ethylsulfide (BPTES), a highly specific and potent uncompetitive inhibitor of this glutaminase. BPTES is also the lead compound for development of novel cancer chemotherapeutic agents. To provide a preliminary assessment of the potential effects of N-acetylation, the corresponding lysine to alanine mutations were constructed in the hGACΔ1 plasmid. The wild type and mutated proteins were purified by Ni(+)-affinity chromatography and their phosphate activation and BPTES inhibition profiles were analyzed. Two of the alanine substitutions in the loop segment (K311A and K328A) and the one in the dimer:dimer interface (K396A) form enzymes that require greater concentrations of phosphate to produce half-maximal activation and exhibit greater sensitivity to BPTES inhibition. By contrast, the K320A mutation results in a glutaminase that exhibits near maximal activity in the absence of phosphate and is not inhibited by BPTES. Thus, lysine N-acetylation may contribute to the acute regulation of glutaminase activity in various tissues and alter the efficacy of BPTES-type inhibitors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Calcium phosphate glass-ceramics for bioactive coating on a β-titanium alloy

International Nuclear Information System (INIS)

Kasuga, T.; Nogami, M.; Niinomi, M.

2003-01-01

The formation of a porous coating is the decisive feature for the bio-compatibility of silica-free calcium phosphate glass ceramics on alloy surfaces like the β-Ti structured Ti-29Nb-13Ta-4.6Zr used in this work. The ceramic composition is highly important: 50CaO-40P 2 O 5 -7Na 2 O-3TiO 2 glass powder produces a pore-free coating unable to bind hydroxyapatite, whereas 60CaO-30P 2 O 5 -7Na 2 O-3TiO 2 glass incorporates pores from which a crystalline hydroxyapatite phase can grow over the surface from simulated body fluid (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Hanford phosphate precipitation filtration process evaluation

International Nuclear Information System (INIS)

Walker, B.W.; McCabe, D.J.

1997-01-01

The purpose of this filter study was to evaluate cross-flow filtration as effective solid-liquid separation technology for treating Hanford wastes, outline operating conditions for equipment, examine the expected filter flow rates, and determine proper cleaning. A proposed Hanford waste pre-treatment process uses sodium hydroxide at high temperature to remove aluminum from sludge. This process also dissolves phosphates. Upon cooling to 40 degrees centigrade the phosphates form a Na7(PO4)2F9H2O precipitate which must be removed prior to further treatment. Filter studies were conducted with a phosphate slurry simulant to evaluate whether 0.5 micron cross-flow sintered metal Mott filters can separate the phosphate precipitate from the wash solutions. The simulant was recirculated through the filters at room temperature and filtration performance data was collected

Biosynthesis and characterization of layered iron phosphate

International Nuclear Information System (INIS)

Zhou Weijia; He Wen; Wang Meiting; Zhang Xudong; Yan Shunpu; Tian Xiuying; Sun Xianan; Han Xiuxiu; Li Peng

2008-01-01

Layered iron phosphate with uniform morphology has been synthesized by a precipitation method with yeast cells as a biosurfactant. The yeast cells are used to regulate the nucleation and growth of layered iron phosphate. The uniform layered structure is characterized by small-angle x-ray diffraction (SAXD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. Fourier transform infrared spectroscopy (FT-IR) is used to analyze the chemical bond linkages in organic–inorganic hybrid iron phosphate. The likely synthetic mechanism of nucleation and oriented growth is discussed. The electrical conductivity of hybrid iron phosphate heat-treated at different temperatures is presented

Sorption of cesium on titanium and zirconium phosphates

International Nuclear Information System (INIS)

Lebedev, V.N.; Mel'nik, N.A.; Rudenko, A.V.

2003-01-01

Titanium and zirconium phosphates were prepared from mineral raw materials of the Kola Peninsula. Their capability to recover cesium cations from the model solutions and liquid radioactive waste (LRW) was studied. Titanium phosphate prepared from solutions formed by titanite breakdown demonstrates greater distribution coefficients of cesium as compared to zirconium phosphate. Titanium phosphate as a cheaper agent featuring greater sorption capacity was recommended for treatment of LRW to remove cesium [ru

Evaluation of in situ capping with clean soils to control phosphate release from sediments

Energy Technology Data Exchange (ETDEWEB)

Xu, Di [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Ding, Shiming, E-mail: smding@niglas.ac.cn [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Sun, Qin [College of Environmental Science and Engineering, Hohai University, Nanjing (China); Zhong, Jicheng [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Wu, Wei; Jia, Fei [College of Environmental Science and Engineering, Hohai University, Nanjing (China)

2012-11-01

Evaluation of in situ capping with clean soils to control phosphate release from the sediments of a eutrophic bay in Lake Taihu was performed after 18 months of capping. The concentrations of dissolved reactive phosphate (DRP) in pore waters and DRP resupply from native sediments and capped sediments were determined using high-resolution dialysis (HR-Peeper) and a Zr-oxide diffusive gradients in thin films (Zr-oxide DGT) technique. The adsorption isotherm of these sediments was further investigated using a modified Langmuir model. The results showed low concentrations of DRP in pore waters with a low resupply from the sediments for sustaining pore water DRP concentration after capping. The calculated flux to the overlying water following the capping treatment was approximately half of that for the native sediments, implying that the capping reduced the release of phosphate from the sediments. The low resupply of the sediments after capping was further demonstrated by larger partitioning coefficient (K{sub p}) values and greater adsorption capacity (Q{sub max}) values, while zero equilibrium concentrations (EPC{sub 0}s) were similar to those in native sediments. The larger K{sub p} and Q{sub max} were attributed to higher active Fe and Al introduced by the capping, indicating that the binding of phosphate onto the active Fe and Al played a critical role in reducing the internal loading of phosphorous. Highlights: Black-Right-Pointing-Pointer Evaluation of capping with soils was performed through high-resolution sampling. Black-Right-Pointing-Pointer Capping decreased the concentrations of DRP in pore waters and its release to waters. Black-Right-Pointing-Pointer Capping decreased the resupply of pore water DRP from the sediments. Black-Right-Pointing-Pointer Capped sediments had stronger abilities to adsorb and retain P. Black-Right-Pointing-Pointer Active Fe and Al introduced by capping played a critical role.

Evaluation of in situ capping with clean soils to control phosphate release from sediments

International Nuclear Information System (INIS)

Xu, Di; Ding, Shiming; Sun, Qin; Zhong, Jicheng; Wu, Wei; Jia, Fei

2012-01-01

Evaluation of in situ capping with clean soils to control phosphate release from the sediments of a eutrophic bay in Lake Taihu was performed after 18 months of capping. The concentrations of dissolved reactive phosphate (DRP) in pore waters and DRP resupply from native sediments and capped sediments were determined using high-resolution dialysis (HR-Peeper) and a Zr-oxide diffusive gradients in thin films (Zr-oxide DGT) technique. The adsorption isotherm of these sediments was further investigated using a modified Langmuir model. The results showed low concentrations of DRP in pore waters with a low resupply from the sediments for sustaining pore water DRP concentration after capping. The calculated flux to the overlying water following the capping treatment was approximately half of that for the native sediments, implying that the capping reduced the release of phosphate from the sediments. The low resupply of the sediments after capping was further demonstrated by larger partitioning coefficient (K p ) values and greater adsorption capacity (Q max ) values, while zero equilibrium concentrations (EPC 0 s) were similar to those in native sediments. The larger K p and Q max were attributed to higher active Fe and Al introduced by the capping, indicating that the binding of phosphate onto the active Fe and Al played a critical role in reducing the internal loading of phosphorous. Highlights: ► Evaluation of capping with soils was performed through high-resolution sampling. ► Capping decreased the concentrations of DRP in pore waters and its release to waters. ► Capping decreased the resupply of pore water DRP from the sediments. ► Capped sediments had stronger abilities to adsorb and retain P. ► Active Fe and Al introduced by capping played a critical role.

Method of decomposing treatment for radioactive organic phosphate wastes

International Nuclear Information System (INIS)

Uki, Kazuo; Ichihashi, Toshio; Hasegawa, Akira; Sato, Tatsuaki

1985-01-01

Purpose: To decompose the organic phosphoric-acid ester wastes containing radioactive material, which is produced from spent fuel reprocessing facilities, into inorganic materials using a simple device, under moderate conditions and at high decomposing ratio. Method: Radioactive organic phosphate wates are oxidatively decomposed by H 2 O 2 in an aqueous phosphoric-acid solution of metal phosphate salts. Copper phosphates are used as the metal phosphate salts and the decomposed solution of the radioactive organic phosphate wastes is used as the aqueous solution of the copper phosphate. The temperature used for the oxidizing decomposition ranges from 80 to 100 0 C. (Ikeda, J.)

Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses

Energy Technology Data Exchange (ETDEWEB)

ALAM,TODD M.

1999-12-21

Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.

A novel twist on molecular interactions between thioredoxin and nicotinamide adenine dinucleotide phosphate-dependent thioredoxin reductase

DEFF Research Database (Denmark)

Kirkensgaard, Kristine Groth; Hägglund, Per; Shahpiri, Azar

2013-01-01

The ubiquitous disulfide reductase thioredoxin (Trx) regulates several important biological processes such as seed germination in plants. Oxidized cytosolic Trx is regenerated by nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase (NTR) in a multistep transfer...... dinucleotide (FAD)-binding domain of HvNTR2 to strongly affect the interaction with Trx. In particular, Trp42 and Met43 play key roles for recognition of the endogenous HvTrxh2. Trx from Arabidopsis thaliana is also efficiently recycled by HvNTR2 but turnover in this case appears to be less dependent...

Nucleos: a web server for the identification of nucleotide-binding sites in protein structures.

Science.gov (United States)

Parca, Luca; Ferré, Fabrizio; Ausiello, Gabriele; Helmer-Citterich, Manuela

2013-07-01

Nucleos is a web server for the identification of nucleotide-binding sites in protein structures. Nucleos compares the structure of a query protein against a set of known template 3D binding sites representing nucleotide modules, namely the nucleobase, carbohydrate and phosphate. Structural features, clustering and conservation are used to filter and score the predictions. The predicted nucleotide modules are then joined to build whole nucleotide-binding sites, which are ranked by their score. The server takes as input either the PDB code of the query protein structure or a user-submitted structure in PDB format. The output of Nucleos is composed of ranked lists of predicted nucleotide-binding sites divided by nucleotide type (e.g. ATP-like). For each ranked prediction, Nucleos provides detailed information about the score, the template structure and the structural match for each nucleotide module composing the nucleotide-binding site. The predictions on the query structure and the template-binding sites can be viewed directly on the web through a graphical applet. In 98% of the cases, the modules composing correct predictions belong to proteins with no homology relationship between each other, meaning that the identification of brand-new nucleotide-binding sites is possible using information from non-homologous proteins. Nucleos is available at http://nucleos.bio.uniroma2.it/nucleos/.

The effect of different phosphate ion concentrations and ph of the phosphate buffer on lipase bioproduction by rhizopus oligosporus

International Nuclear Information System (INIS)

Haq, I.; Ali, S.; Awan, U.F.; Javed, W.; Mirza, S.

2005-01-01

In the present investigation, we report the effect of phosphate ion concentration and different ph of the phosphate buffer (as diluent) on lipase bioproduction by Rhizopus oligosporus. For this purpose, solid state fermentation was employed. Different agricultural by-products such as wheat bran, rice husk, almond meal, soybean meal and sunflower meal were used as substrate. The maximum lipase activity (72.60 U/g) was observed with the almond meal. Addition of phosphate ions (K/sub 2/HPO/sub 4/) influenced the lipase production. The ph of the phosphate buffer (7.0) was found to be effective for higher yield of lipase. (author)

The calcium phosphate coating of soy lecithin nanoemulsion with performance in stability and as an oxygen carrier

Science.gov (United States)

Han, Kyu B.

This work studied the relationship between surfactant, oil, and water, by building ternary phase diagrams, the goal of which was to identify the oil-in-water phase composition. The resulting nano-sized emulsion was coated with dicalcium phosphate by utilizing the ionic affinity between calcium ions and the emulsion surface. Since the desired function of the particle is as an oxygen carrier, the particle stability, oxygen capacity, and oxygen release rate were investigated. The first step in the process was to construct ternary phase diagrams with 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) and soy derived lecithin. The results showed that the lecithin surfactant formed an oil-in-water phase region that was 36 times greater than that of DOPA. With the desired phase composition set, the lecithin emulsion was extruded, resulting in a well-dispersed nanosized particle. A pH titration study of the emulsion found an optimized calcium phosphate coating condition at pH 8.8, at which, the calcium ion had a greater affinity for the emulsion surface than phosphate. A Hill plot was used to show calcium cooperativeness on the emulsion surface which suggested one calcium ion binds to one lecithin molecule. The lecithin emulsion particles were then coated with calcium phosphate using a layering technique that allowed for careful control of the coating thickness. The overall particle hydrodynamic radius was consistent with the growth of the calcium phosphate coating, from 8 nm to 28 nm. This observation was further supported with cryo-TEM measurements. The stability of the coated emulsion was tested in conditions that simulate practical thermal, physical, and time-dependent conditions. Throughout the tests, the coated emulsion exhibited a constant mono-dispersed particle size, while the uncoated emulsion size fluctuated greatly and exhibited increased polydispersion. The fast mixing method with the stopped-flow apparatus was employed to test the product as an oxygen carrier, and it

Intracellular and extracellular phosphatidylinositol 3-phosphate produced by Phytophthora species is important for infection.

Science.gov (United States)

Lu, Shan; Chen, Linlin; Tao, Kai; Sun, Nannan; Wu, Yuren; Lu, Xiaoxue; Wang, Yuanchao; Dou, Daolong

2013-09-01

RxLR effectors produced by Phytophthora pathogens have been proposed to bind to phosphatidylinositol 3-phosphate (PtdIns(3)P) to mediate their translocation into host cells and/or to increase their stability in planta. Since the levels of PtdIns(3)P in plants are low, we examined whether Phytophthora species may produce PtdIns(3)P to promote infection. We observed that PtdIns(3)P-specific GFP biosensors could bind to P. parasitica and P. sojae hyphae during infection of Nicotiana benthamiana leaves transiently secreting the biosensors, suggesting that the hyphae exposed PtdIns(3)P on their plasma membrane and/or secreted PtdIns(3)P. Silencing of the phosphatidylinositol 3-kinases (PI3K) genes, treatment with LY294002, or expression of PtdIns(3)P-binding proteins by P. sojae reduced the virulence of the pathogen on soybean, indicating that pathogen-synthesized PtdIns(3)P was required for full virulence. Secretion of PtdIns(3)P-binding proteins or of a PI3P-5-kinase by N. benthamiana leaves significantly increased the level of resistance to infection by P. parasitica and P. capsici. Together, our results support the hypothesis that Phytophthora species produce external PtdIns(3)P to aid in infection, such as to promote entry of RxLR effectors into host cells. Our results derived from P. sojae RxLR effector Avr1b confirm that both the N-terminus and the C-terminus of this effector can bind PtdIns(3)P.

The EIS investigation of powder polyester coatings on phosphated low carbon steel: The effect of NaNO2 in the phosphating bath

International Nuclear Information System (INIS)

Jegdic, B.V.; Bajat, J.B.; Popic, J.P.; Stevanovic, S.I.; Miskovic-Stankovic, V.B.

2011-01-01

Highlights: → The effect of NaNO 2 on surface morphology of iron-phosphate coatings were determined. → Better corrosion stability of polyester coating on phosphated steel without NaNO 2 . → EIS results and microscopic examinations correlate well with adhesion measurements. - Abstract: The effect of different type of iron-phosphate coatings on corrosion stability and adhesion characteristic of top powder polyester coating on steel was investigated. Iron-phosphate coatings were deposited on steel in the novel phosphating bath with or without NaNO 2 as an accelerator. The corrosion stability of the powder polyester coating was evaluated by electrochemical impedance spectroscopy (EIS), adhesion by pull-off and NMP test, while surface morphology of phosphate coatings were investigated by atomic force microscopy (AFM). The adhesion and corrosion stability of powder polyester coatings were improved with pretreatment based on iron-phosphate coating deposited from NaNO 2 -free bath.

Electrochemical Sensing of Casein Based on the Interaction between Its Phosphate Groups and a Ruthenium(III) Complex.

Science.gov (United States)

Inaba, Iku; Kuramitz, Hideki; Sugawara, Kazuharu

2016-01-01

A reaction to casein, along with β-lactoglobulin, is a main cause of milk allergies, and also is a useful indicator of protein in allergic analyses. In the present study, a simple casein sensor was developed based on the interaction between a phosphate group of casein and electroactive [Ru(NH3)6](3+). We evaluated the voltammetric behavior of a casein-[Ru(NH3)6](3+) complex using a glassy carbon electrode. When the ruthenium(III) complex was combined with the phosphate groups of casein, the structure of the casein was changed. Since the hydrophobicity of casein was increased due to the binding, the casein was adsorbed onto the electrode. Furthermore, we modified an electrode with a ruthenium(III) ions/collagen film. When the sensor was applied to the detection of the casein contained in milk, the values coincided with those indicated by the manufacturer. Accordingly, this electrode could be a powerful sensor for the determination of casein in several foods.

Multilayer Choline Phosphate Molecule Modified Surface with Enhanced Cell Adhesion but Resistance to Protein Adsorption.

Science.gov (United States)

Chen, Xingyu; Yang, Ming; Liu, Botao; Li, Zhiqiang; Tan, Hong; Li, Jianshu

2017-08-22

Choline phosphate (CP), which is a new zwitterionic molecule, and has the reverse order of phosphate choline (PC) and could bind to the cell membrane though the unique CP-PC interaction. Here we modified a glass surface with multilayer CP molecules using surface-initiated atom-transfer radical polymerization (SI-ATRP) and the ring-opening method. Polymeric brushes of (dimethylamino)ethyl methacrylate (DMAEMA) were synthesized by SI-ATRP from the glass surface. Then the grafted PDMAEMA brushes were used to introduce CP groups to fabricate the multilayer CP molecule modified surface. The protein adsorption experiment and cell culture test were used to evaluate the biocompatibility of the modified surfaces by using human umbilical veinendothelial cells (HUVECs). The protein adsorption results demonstrated that the multilayer CP molecule decorated surface could prevent the adsorption of fibrinogen and serum protein. The adhesion and proliferation of cells were improved significantly on the multilayer CP molecule modified surface. Therefore, the biocompatibility of the material surface could be improved by the modified multilayer CP molecule, which exhibits great potential for biomedical applications, e.g., scaffolds in tissue engineering.

Radiological impact of use of phosphate fertilizers

International Nuclear Information System (INIS)

Shukla, V.K.; Chinnaesakki, S.; Sartandel, S.J.; Shanbhag, A.A.; Puranik, V.D.

2003-01-01

The paper describes the results of gamma spectrometric measurements of 238 U, 233 Th, 226 Ra and 40 K in rock phosphates and various types of phosphate fertilizers and by-products. The increase in soil natural radioactivity has been assessed for major Indian crops. No significant increase in soil natural radioactivity is expected due to the application of phosphate fertilizers for agricultural productions. (author)

Fructose 1-phosphate is the one and only physiological effector of the Cra (FruR) regulator of Pseudomonas putida.

Science.gov (United States)

Chavarría, Max; Durante-Rodríguez, Gonzalo; Krell, Tino; Santiago, César; Brezovsky, Jan; Damborsky, Jiri; de Lorenzo, Víctor

2014-01-01

Fructose-1-phosphate (F1P) is the preferred effector of the catabolite repressor/activator (Cra) protein of the soil bacterium Pseudomonas putida but its ability to bind other metabolic intermediates in vivo is unclear. The Cra protein of this microorganism (Cra(PP)) was submitted to mobility shift assays with target DNA sequences (the PfruB promoter) and candidate effectors fructose-1,6-bisphosphate (FBP), glucose 6-phosphate (G6P), and fructose-6-phosphate (F6P). 1 mM F1P was sufficient to release most of the Cra protein from its operators but more than 10 mM of FBP or G6P was required to free the same complex. However, isothermal titration microcalorimetry failed to expose any specific interaction between Cra(PP) and FBP or G6P. To solve this paradox, transcriptional activity of a PfruB-lacZ fusion was measured in wild-type and ΔfruB cells growing on substrates that change the intracellular concentrations of F1P and FBP. The data indicated that PfruB activity was stimulated by fructose but not by glucose or succinate. This suggested that Cra(PP) represses expression in vivo of the cognate fruBKA operon in a fashion dependent just on F1P, ruling out any other physiological effector. Molecular docking and dynamic simulations of the Cra-agonist interaction indicated that both metabolites can bind the repressor, but the breach in the relative affinity of Cra(PP) for F1P vs FBP is three orders of magnitude larger than the equivalent distance in the Escherichia coli protein. This assigns the Cra protein of P. putida the sole role of transducing the presence of fructose in the medium into a variety of direct and indirect physiological responses.

Exploring substrate binding and discrimination in fructose1, 6-bisphosphate and tagatose 1,6-bisphosphate aldolases.

Science.gov (United States)

Zgiby, S M; Thomson, G J; Qamar, S; Berry, A

2000-03-01

Fructose 1,6-bisphosphate aldolase catalyses the reversible condensation of glycerone-P and glyceraldehyde 3-phosphate into fructose 1,6-bisphosphate. A recent structure of the Escherichia coli Class II fructose 1,6-bisphosphate aldolase [Hall, D.R., Leonard, G.A., Reed, C.D., Watt, C.I., Berry, A. & Hunter, W.N. (1999) J. Mol. Biol. 287, 383-394] in the presence of the transition state analogue phosphoglycolohydroxamate delineated the roles of individual amino acids in binding glycerone-P and in the initial proton abstraction steps of the mechanism. The X-ray structure has now been used, together with sequence alignments, site-directed mutagenesis and steady-state enzyme kinetics to extend these studies to map important residues in the binding of glyceraldehyde 3-phosphate. From these studies three residues (Asn35, Ser61 and Lys325) have been identified as important in catalysis. We show that mutation of Ser61 to alanine increases the Km value for fructose 1, 6-bisphosphate 16-fold and product inhibition studies indicate that this effect is manifested most strongly in the glyceraldehyde 3-phosphate binding pocket of the active site, demonstrating that Ser61 is involved in binding glyceraldehyde 3-phosphate. In contrast a S61T mutant had no effect on catalysis emphasizing the importance of an hydroxyl group for this role. Mutation of Asn35 (N35A) resulted in an enzyme with only 1.5% of the activity of the wild-type enzyme and different partial reactions indicate that this residue effects the binding of both triose substrates. Finally, mutation of Lys325 has a greater effect on catalysis than on binding, however, given the magnitude of the effects it is likely that it plays an indirect role in maintaining other critical residues in a catalytically competent conformation. Interestingly, despite its proximity to the active site and high sequence conservation, replacement of a fourth residue, Gln59 (Q59A) had no significant effect on the function of the enzyme. In a

Exploring plant factors for increasing phosphorus utilization from rock phosphates and native soil phosphates in acidic soils

International Nuclear Information System (INIS)

Feng Guanglin; Xiong Liming

2002-01-01

Six plant species with contrasting capacity in utilizing rock phosphates were compared with regard to their responses to phosphorus starvation in hydroponic cultures. Radish, buckwheat and oil rapeseed are known to have strong ability to use rock phosphates while ryegrass, wheat and sesbania are less efficient. Whereas other plants acidified their culture solution under P starvation (-P), radish plants make alkaline the solution. When neutralizing the pH of the solutions cultured with plants under either -P or + P conditions, solutions with P starved buckwheat, rapeseed, and radish had a higher ability to solubilize Al and Fe phosphates than did those cultured with sesbania, ryegrass and wheat. Characterization of organic ligands in the solutions identified that citrate and malate were the major organic anions exuded by rapeseed and radish. Besides citrate and malate, buckwheat exuded a large amount of tartrate under P starvation. In contrast, ryegrass, wheat and sesbania secreted only a limited amount of oxalic acid, regardless of P status. Changes in activities of phosphoenolpyruvate carboxylase, acid phosphatase, and nitrate reductase in these plants were also compared under P- sufficient or -deficient conditions. The results indicated that plant ability to use rock phosphates or soil phosphates is closely related to their responses toward P starvation. The diversity of P starvation responses was discussed in the context of co-evolution between plants and their environment. Approaches to use plant factors to enhance the effectiveness of rock phosphates were also discussed. (author)

The phosphate balance : current developments and future outlook

NARCIS (Netherlands)

Enk, van R.J.; Vee, van der G.; Acera, L.K.; Schuiling, R.; Ehlert, P.A.I.

2011-01-01

Phosphate is essential for agricultural production and therefore plays a key role in the global production of food and biofuels. There are no agricultural alternatives for phosphate, and a substantial fraction of our annual phosphate consumption is dispersed into the environment where it is largely

The phosphate balance : Current developments and future outlook

NARCIS (Netherlands)

Enk, R.J. van; Acera, L.K.; Schuiling, R.D.; Ehlert, P.; de Wilt, J.G.; van Haren, R.J.F.

2011-01-01

Phosphate is essential for agricultural production and therefore plays a key role in the global production of food and biofuels. There are no agricultural alternatives for phosphate, and a substantial fraction of our annual phosphate consumption is dispersed into the environment where it is largely

Radiological impacts of uranium recovery in the phosphate industry

International Nuclear Information System (INIS)

Ryan, M.T.

1981-01-01

This article characterizes the occupational and public radiological health impacts associated with phosphate mining and milling. These impacts are related to the phosphate industry's uranium production potential and are compared with those associated with conventional uranium mining and milling. The radiological impacts resulting from occupational and nonoccupational exposures are assessed. Occupational exposures in phosphate facilities are compared to background exposures and radiological population dose assessments, which characterize important radionuclides and exposure pathways. The following conclusions were reached: (1) public consequences of phosphate mining will occur whether or not uranium is recovered as a by-product, (2) radiological consequences of phosphate mining may be comparable to those associated with uranium mining and milling per unit uranium production, (3) radiological impacts via surface waterways and crops fertilized with uranium-bearing phosphates are of minor consequence, and (4) major radiological public health problems associated with phosphate mining are related to radon and radon progeny exposures in structures built on reclaimed lands or with phosphate mining residues, although the magnitudes of these impacts are difficult to evaluate with current data

2,3-DPG-Hb complex: a hypothesis for an asymmetric binding.

Science.gov (United States)

Pomponi, M; Bertonati, C; Fuglei, E; Wiig, O; Derocher, A E

2000-05-15

This study was undertaken to test the symmetry of 2,3-diphosphoglycerate (2,3-DPG) binding site in hemoglobin (Hb). From Arnone's study [A. Arnone, Nature (London) 237 (1972) 146] the 2,3-DPG binding site is located at the top of the cavity, that runs through the center of the deoxy-Hb molecule. However, it is possible that this symmetry reported by Arnone, for crystals of 2,3-DPG-Hb complex, might not be conserved in solution. In this paper, we report the 31P nuclear magnetic resonances of the 2,3-DPG interaction with Hb. The 2,3-DPG chemical shifts of the P2 and P3 resonance are both pH- and hemoglobin-dependent [protein from man, polar bear (Ursus maritimus), Arctic fox (Alopex lagopus) and bovine]. 2,3-DPG binds tightly to deoxyhemoglobin and weakly, nevertheless significantly, to oxyhemoglobin. In particular, our results suggest similar spatial position of the binding site of 2,3-DPG in both forms of Hb in solutions. However, the most unexpected result was the apparent loss of symmetry in the binding site, which might correlate with the ability of the hemoglobin to modulate its functional behavior. The different interactions of the phosphate groups indicate small differences in the quaternary structure of the different deoxy forms of hemoglobin. Given the above structural perturbation an asymmetric binding in the complex could justify, at least in part, different physiological properties of Hb. Regardless, functionally relevant effects of 2,3-DPG seem to be measured and best elucidated through solution studies.

Physico-chemical characterization of Ogun and Sokoto phosphate ...

African Journals Online (AJOL)

Gypsum, calcite and lime were associated with both rock phosphates indicating their liming potential in the soil. ORP was more soluble in water, probably because it ... fertilizers and direct application in crop production. Keywords: Phosphorus, apatite, crop production, fertilizer, Ogun rock phosphate, Sokoto rock phosphate ...

Fourier transform Raman spectroscopy of synthetic and biological calcium phosphates.

Science.gov (United States)

Sauer, G R; Zunic, W B; Durig, J R; Wuthier, R E

1994-05-01

Fourier-transform (FT) Raman spectroscopy was used to characterize the organic and mineral components of biological and synthetic calcium phosphate minerals. Raman spectroscopy provides information on biological minerals that is complimentary to more widely used infrared methodologies as some infrared-inactive vibrational modes are Raman-active. The application of FT-Raman technology has, for the first time, enabled the problems of high sample fluorescence and low signal-to-noise that are inherent in calcified tissues to be overcome. Raman spectra of calcium phosphates are dominated by a very strong band near 960 cm-1 that arises from the symmetric stretching mode (v1) of the phosphate group. Other Raman-active phosphate vibrational bands are seen at approximately 1075 (v3), 590 (v4), and 435 cm-1 (v2). Minerals containing acidic phosphate groups show additional vibrational modes. The different calcium phosphate mineral phases can be distinguished from one another by the relative positions and shapes of these bands in the Raman spectra. FT-Raman spectra of nascent, nonmineralized matrix vesicles (MV) show a distinct absence of the phosphate v1 band even though these structures are rich in calcium and phosphate. Similar results were seen with milk casein and synthetic Ca-phosphatidyl-serine-PO4 complexes. Hence, the phosphate and/or acidic phosphate ions in these noncrystalline biological calcium phosphates is in a molecular environment that differs from that in synthetic amorphous calcium phosphate. In MV, the first distinct mineral phase to form contained acidic phosphate bands similar to those seen in octacalcium phosphate. The mineral phase present in fully mineralized MV was much more apatitic, resembling that found in bones and teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper tolerance in Frankia sp. strain EuI1c involves surface binding and copper transport.

Science.gov (United States)

Rehan, Medhat; Furnholm, Teal; Finethy, Ryan H; Chu, Feixia; El-Fadly, Gomaah; Tisa, Louis S

2014-09-01

Several Frankia strains have been shown to be copper-tolerant. The mechanism of their copper tolerance was investigated for Frankia sp. strain EuI1c. Copper binding was shown by binding studies. Unusual globular structures were observed on the surface of the bacterium. These globular structures were composed of aggregates containing many relatively smaller "leaf-like" structures. Scanning electron microscopy with energy-dispersive X-ray (SEM-EDAX) analysis of these structures indicated elevated copper and phosphate levels compared to the control cells. Fourier transform infrared spectroscopy (FTIR) analysis indicated an increase in extracellular phosphate on the cell surface of copper-stressed cells. Bioinformatics' analysis of the Frankia sp. strain EuI1c genome revealed five potential cop genes: copA, copZ, copC, copCD, and copD. Experiments with Frankia sp. strain EuI1c using qRT-PCR indicated an increase in messenger RNA (mRNA) levels of the five cop genes upon Cu(2+) stress. After 5 days of Cu(2+) stress, the copA, copZ, copC, copCD, and copD mRNA levels increased 25-, 8-, 18-, 18-, and 25-fold, respectively. The protein profile of Cu(2+)-stressed Frankia sp. strain EuI1c cells revealed the upregulation of a 36.7 kDa protein that was identified as FraEuI1c_1092 (sulfate-binding periplasmic transport protein). Homologues of this gene were only present in the genomes of the Cu(2+)-resistant Frankia strains (EuI1c, DC12, and CN3). These data indicate that copper tolerance by Frankia sp. strain EuI1c involved the binding of copper to the cell surface and transport proteins.

Phosphate recycling in the phosphorus industry

NARCIS (Netherlands)

Schipper, W.J.; Klapwijk, A.; Potjer, B.; Rulkens, W.H.; Temmink, B.G.; Kiestra, F.D.G.; Lijmbach, A.C.M.

2004-01-01

The article describes the potential and limitations for recovery of phosphate from secondary materials in the production process for white phosphorus. This thermal process involves the feeding of phosphate rock, cokes and pebbles to a furnace. The reducing conditions in the furnace promote the

Standard characterization of phosphate rock samples from the FAO/IAEA phosphate project

International Nuclear Information System (INIS)

Binh, Truong; Zapata, F.

2002-01-01

Phosphate rocks (PR) are phosphate-bearing minerals that vary widely in their inherent characteristics and consequently their agronomic potential. In the framework of a FAO/IAEA networked research project, the evaluation of the agronomic effectiveness of natural and modified PR products under a variety of soil climate and crop management conditions was carried out. The characterization of phosphate rocks is the first and essential step in evaluating their suitability for direct application. If several PR sources are utilized, standardized methods should be used for comparison purposes to determine their agronomic potential. This paper describes the standard characterization of phosphate rock products utilized in the project, in particular the mineralogical and crystallographic analyses, physical analyses, chemical composition and solubility in conventional reagents. A total of 28 phosphate rock samples from 15 countries were collected and analyzed in specialized laboratories. The data on mineralogy, chemical composition and solubility in conventional reagents are closely interrelated. An arbitrary classification of the reactivity of the PR samples was made based on the solubility indices in conventional reagents. On another hand, the results of the crystallographic parameters, calculated indices of absolute solubility, specific surface and porosity reflect the variability of the physical state and the sample pre-conditioning treatment of the analyzed products. A proper characterization of phosphate rock samples should provide the maximum of basic information that can be obtained in a cost-effective manner in normal chemical laboratories. Based on the results of this characterization, the following determinations are recommended: a description of the sample, major elemental (total P, Ca, Mg) composition, solubility in conventional reagents (neutral ammonium citrate, citric and formic acid) and particle size analysis. The classification of PR samples for direct

Radio phosphorus kinetics in the blood of sheep supplemented with dicalcium phosphate, mono ammonium phosphate, triple superphosphate and Tapira rock phosphate

International Nuclear Information System (INIS)

Abdalla, A.L.

1992-01-01

With the aim to study the kinetics of radio phosphorus ( 32 P) in the blood of animals supplemented with dicalcium phosphate (BIC), mono ammonium phosphate (MAP), triple superphosphate (SPT) and Tapira rock phosphate (TAP), 32 male sheep were kept in metabolic cages at the Animal Science Section / CENA - USP. Plasma was obtained by centrifugation and the specific activity, rate of disappearance and half life of 32 P in plasma were determined. In the red blood cells were determined the uptake rate of the radioisotope, the rate of disappearance and half life of 32 P up taken. It was observed a statistical significant difference (p 32 P in the plasma and erythrocytes. The specific activity and half life of 32 P in the plasma were statistically different (p<0,10) among sheep receiving the different phosphorus sources; the same was observed in respect to the red blood cells. It was concluded that the supplemented phosphorus source given in the diet of sheep may affect the kinetics of the radio phosphorus in the blood after been intravenously injected. (author)

Overexpression, crystallization and preliminary X-ray analysis of xylulose-5-phosphate/fructose-6-phosphate phosphoketolase from Bifidobacterium breve

International Nuclear Information System (INIS)

Suzuki, Ryuichiro; Kim, Byung-Jun; Shibata, Tsuyoshi; Iwamoto, Yuki; Katayama, Takane; Ashida, Hisashi; Wakagi, Takayoshi; Shoun, Hirofumi; Fushinobu, Shinya; Yamamoto, Kenji

2010-01-01

Xylulose-5-phosphate/fructose-6-phosphate phosphoketolase from B. breve was overexpressed and crystallized. The crystals belonged to the tetragonal space group I422 and diffracted to beyond 1.7 Å resolution. The xylulose-5-phosphate/fructose-6-phosphate phosphoketolase gene from Bifidobacterium breve was cloned and overexpressed in Escherichia coli. The enzyme was purified to homogeneity and crystallized by the sitting-drop vapour-diffusion method. Crystals were obtained at 293 K using 0.05 mM thiamine diphosphate, 0.25 mM MgCl 2 , 24%(w/v) PEG 6000 and 0.1 M Bicine pH 9.0. The crystals belonged to the tetragonal space group I422, with unit-cell parameters a = b = 174.8, c = 163.8 Å, and diffracted to beyond 1.7 Å resolution

Structure of alanine racemase from Oenococcus oeni with bound pyridoxal 5′-phosphate

International Nuclear Information System (INIS)

Palani, Kandavelu; Burley, Stephen K.; Swaminathan, Subramanyam

2012-01-01

Alanine racemase from O. oeni exists as a dimer in the crystal structure. Both monomers contribute to the two active sites present, one for each monomer. The crystal structure of alanine racemase from Oenococcus oeni has been determined at 1.7 Å resolution using the single-wavelength anomalous dispersion (SAD) method and selenium-labelled protein. The protein exists as a symmetric dimer in the crystal, with both protomers contributing to the two active sites. Pyridoxal 5′-phosphate, a cofactor, is bound to each monomer and forms a Schiff base with Lys39. Structural comparison of alanine racemase from O. oeni (Alr) with homologous family members revealed similar domain organization and cofactor binding

Vanadate influence on metabolism of sugar phosphates in fungus Phycomyces blakesleeanus.

Directory of Open Access Journals (Sweden)

Milan Žižić

Full Text Available The biological and chemical basis of vanadium action in fungi is relatively poorly understood. In the present study, we investigate the influence of vanadate (V5+ on phosphate metabolism of Phycomyces blakesleeanus. Addition of V5+ caused increase of sugar phosphates signal intensities in 31P NMR spectra in vivo. HPLC analysis of mycelial phosphate extracts demonstrated increased concentrations of glucose 6 phosphate, fructose 6 phosphate, fructose 1, 6 phosphate and glucose 1 phosphate after V5+ treatment. Influence of V5+ on the levels of fructose 2, 6 phosphate, glucosamine 6 phosphate and glucose 1, 6 phosphate (HPLC, and polyphosphates, UDPG and ATP (31P NMR was also established. Increase of sugar phosphates content was not observed after addition of vanadyl (V4+, indicating that only vanadate influences its metabolism. Obtained results from in vivo experiments indicate catalytic/inhibitory vanadate action on enzymes involved in reactions of glycolysis and glycogenesis i.e., phosphoglucomutase, phosphofructokinase and glycogen phosphorylase in filamentous fungi.

Issues of natural radioactivity in phosphates

International Nuclear Information System (INIS)

Schnug, E.; Haneklaus, S.; Schnier, C.; Scholten, L.C.

1996-01-01

The fertilization of phosphorus (P) fertilizers is essential in agricultural production, but phosphates contain in dependence on their origin different amounts of trace elements. The problem of cadmium (Cd) loads and other heavy metals is well known. However, only a limited number of investigations examined the contamination of phosphates with the two heaviest metals, uranium (U) and thorium (Th), which are radioactive. Also potassium (K) is lightly radioactive. Measurements are done n the radioactivity content of phosphates, P fertilizers and soils. The radiation doses to workers and public as well as possible contamination of soils from phosphate rock or fertilizer caused by these elements or their daughter products is of interest with regard to radiation protection. The use of P fertilizers is necessary for a sustainable agriculture, but it involves radioactive contamination of soils. The consequences of the use of P fertilizers is discussed, also with regard to existing and proposed legislation. 11 refs., 2 figs., 7 tabs

Supplementation of inorganic phosphate enhancing the removal efficiency of tannery sludge-borne Cr through bioleaching.

Science.gov (United States)

Zheng, Guanyu; Zhou, Lixiang

2011-10-15

Four inorganic mineral nutrients including NH4+, K+, Mg2+ and soluble inorganic phosphate (Pi) were investigated to reveal the potential limiting nutrients for tannery sludge bioleaching process driven by Acidithiobacillus species, and the feasibility of supplementing the limiting nutrients to accelerate tannery sludge bioleaching was studied in the present study. It was found that the concentration of Pi was lower than 3.5 mg/L throughout the whole bioleaching process, which is the most probable restricting nutrient for tannery sludge bioleaching. Further experiments revealed that the deficiency of Pi could seriously influence the growth of Acidithiobacillus thiooxidans and lower its oxidization capacity for S0, and the limiting concentration of Pi for the growth of A. thiooxidans was 6 mg/L. The low concentration of soluble Pi in sludge matrix was resulted from the extremely strong sorbing/binding capacity of tannery sludge for phosphate. The supplementation of more than 1.6 g/L KH2PO4 into tannery sludge bioleaching system could effectively stimulate the growth of Acidithiobacillus species, enhance Cr removal rate and further shorten tannery sludge bioleaching period from 10 days to 7 days. Therefore, inorganic phosphate supplementation is an effective and feasible method to accelerate tannery sludge bioleaching process, and the optimum dosage of KH2PO4 was 1.6 g/L for tannery sludge with 5.1% of total solids. Copyright © 2011 Elsevier Ltd. All rights reserved.

A phosphate-starvation-inducible outermembrane protein of Pseudomonas fluorescens Ag1 as an immunological phosphate-starvation marker

DEFF Research Database (Denmark)

Leopold, Kristine; Jacobsen, Susanne; Nybroe, Ole

1997-01-01

A phosphate-starvation-inducible outer-membrane protein of Pseudomonas fluorescens Ag1, expressed at phosphate concentrations below0.08-0.13 mM, was purified and characterized. The purification method involved separation of outer-membrane proteins by SDS-PAGE andextraction of the protein from...... nitrocellulose or PVDF membranes after electrotransfer of proteins to the membranes. The N-terminal amino acidsequence of the purified protein, called Psi1, did not show homology to any known proteins, and in contrast to the phosphate-specific porin OprP ofP. aeruginosa its mobility in SDS-PAGE was not affected...

Calcium phosphate glass-ceramics for bioactive coating on a {beta}-titanium alloy

Energy Technology Data Exchange (ETDEWEB)

Kasuga, T.; Nogami, M. [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Niinomi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, Tenpaku-cho, Toyohashi 441-8580 (Japan)

2003-07-01

The formation of a porous coating is the decisive feature for the bio-compatibility of silica-free calcium phosphate glass ceramics on alloy surfaces like the {beta}-Ti structured Ti-29Nb-13Ta-4.6Zr used in this work. The ceramic composition is highly important: 50CaO-40P{sub 2}O{sub 5}-7Na{sub 2}O-3TiO{sub 2} glass powder produces a pore-free coating unable to bind hydroxyapatite, whereas 60CaO-30P{sub 2}O{sub 5}-7Na{sub 2}O-3TiO{sub 2} glass incorporates pores from which a crystalline hydroxyapatite phase can grow over the surface from simulated body fluid (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Isolation of phosphate solubiliser fungi from Araza rhizosphere

International Nuclear Information System (INIS)

Vera, Diana Fernanda; Perez, Hernando; Valencia Hernando

2002-01-01

Araza is an eatable plant, original from the Amazon region, which has been described as a promising species for commercialization (Quevedo 1995). This plant has high productivity even in low content phosphate soil but the presence of phosphate solubilizing microorganisms may contribute to increase this element availability. In this study we report the isolation and characterization of solubilizing fungi processed using the soil washing method, from soil samples were araza is cultivated at two regions in Guaviare, Colombia. Eighteen isolates of fungi capable of solubilizing phosphate were obtained from 2 different sources. The most important species that solubilized phosphate from calcium were Trichoderma aureoviride, Aspergillus aculeatus, Trichoderma strain 1 y Trichoderma strain 2 and for phosphate from iron: Aspergillus oryzae, Paecilomyces strain 3, Gongronella butleri and Fusarium oxysporum

Dielectric aluminium phosphate thin films. Couches minces dielectriques de phosphate d'aluminium

Energy Technology Data Exchange (ETDEWEB)

Daviero, S. (Lab. Physicochimie des Materiaux Solides, 34 - Montpellier (France)); Avinens, C. (Lab. Physicochimie des Materiaux Solides, 34 - Montpellier (France)); Ibanez, A. (Lab. Physicochimie des Materiaux Solides, 34 - Montpellier (France)); Giuntini, J.C. (Lab. Physicochimie des Materiaux Solides, 34 -Montpellier (France)); Philippot, E. (Lab. Physicochimie des Materiaux Solides, 34 - Montpellier (France))

1993-04-01

Aluminium phosphate thin films on silicium substrate have been carried out from tributylphosphate and aluminium acetylacetonate precursors in solution through the ''pyrosol'' process. It can be observed a large range of chemical analysis in terms of experimental conditions. These thin films have been characterized by X-ray diffraction and infrared spectrometry. Their electrical characteristics, defined from direct current and alternative current measurements, are quite different to those of the crystallized phosphate and can be explained by P-O and Al-O ''dangling bond'' existence. (orig.).

Phosphate recycling in the phosphorus industry

NARCIS (Netherlands)

Schipper, W.J.; Klapwijk, A.; Potjer, A.; Rulkens, W.H.; Temmink, B.G.; Kiestra, F.D.G.; Lijmbach, A.C.M.

2001-01-01

The feasibility of phosphate recycling in the white phosphorus production process is discussed. Several types of materials may be recycled, provided they are dry inorganic materials, low in iron, copper and zinc. Sewage sludge ash may be used if no iron is used for phosphate precipitation in the

Application of Potential Phosphate-Solubilizing Bacteria and Organic Acids on Phosphate Solubilization from Phosphate Rock in Aerobic Rice

Directory of Open Access Journals (Sweden)

Qurban Ali Panhwar

2013-01-01

Full Text Available A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubilizing bacteria (PSB and organic acids (oxalic & malic on phosphate (P solubilization from phosphate rock (PR and growth of aerobic rice. Four rates of each organic acid (0, 10, 20, and 30 mM, and PSB strain (Bacillus sp. were applied to aerobic rice. Total bacterial populations, amount of P solubilization, P uptake, soil pH, and root morphology were determined. The results of the study showed significantly high P solubilization in PSB with organic acid treatments. Among the two organic acids, oxalic acid was found more effective compared to malic acid. Application of oxalic acid at 20 mM along with PSB16 significantly increased soluble soil P (28.39 mg kg−1, plant P uptake (0.78 P pot−1, and plant biomass (33.26 mg. Addition of organic acids with PSB and PR had no influence on soil pH during the planting period. A higher bacterial population was found in rhizosphere (8.78 log10 cfu g−1 compared to the nonrhizosphere and endosphere regions. The application of organic acids along with PSB enhanced soluble P in the soil solution, improved root growth, and increased plant biomass of aerobic rice seedlings without affecting soil pH.

Isolation and characterization of gelatin-binding proteins from goat seminal plasma

Directory of Open Access Journals (Sweden)

Lazure Claude

2003-04-01

Full Text Available Abstract A family of proteins designated BSP-A1, BSP-A2, BSP-A3 and BSP-30 kDa (collectively called BSP proteins for Bovine Seminal Plasma proteins constitute the major protein fraction in the bull seminal plasma. These proteins interact with choline phospholipids on the sperm surface and play a role in the membrane stabilization (decapacitation and destabilization (capacitation process. Homologous proteins have been isolated from boar and stallion seminal plasma. In the current study we report the isolation and preliminary characterization of homologous proteins from goat seminal plasma. Frozen semen (-80°C was thawed and centrifuged to remove sperm. The proteins in the supernatant were precipitated by the addition of cold ethanol. The precipitates were dissolved in ammonium bicarbonate and lyophilised. The lyophilised proteins were dissolved in phosphate buffer and loaded onto a gelatin-agarose column, which was previously equilibrated with the same buffer. The column was successively washed with phosphate buffer, with phosphate buffer saline and with 0.5 M urea in phosphate buffer saline to remove unadsorbed proteins, and the adsorbed proteins were eluted with 5 M urea in phosphate buffer saline. Analysis of pooled, dialysed and lyophilised gelatin-agarose adsorbed protein fraction by SDS-PAGE indicated the presence of four protein bands that were designated GSP-14 kDa, GSP-15 kDa, GSP-20 kDa and GSP-22 kDa (GSP, Goat Seminal Plasma proteins. Heparin-affinity chromatography was then used for the separation of GSP-20 and -22 kDa from GSP-14 and -15 kDa. Finally, HPLC separation permitted further isolation of each one from the other. Amino acid sequence analysis of these proteins indicated that they are homologous to BSP proteins. In addition, these BSP homologs bind to hen's egg-yolk low-density lipoproteins. These results together with our previous data indicate that BSP family proteins are ubiquitous in mammalian seminal plasma, exist in

Phosphate Framework Electrode Materials for Sodium Ion Batteries.

Science.gov (United States)

Fang, Yongjin; Zhang, Jiexin; Xiao, Lifen; Ai, Xinping; Cao, Yuliang; Yang, Hanxi

2017-05-01

Sodium ion batteries (SIBs) have been considered as a promising alternative for the next generation of electric storage systems due to their similar electrochemistry to Li-ion batteries and the low cost of sodium resources. Exploring appropriate electrode materials with decent electrochemical performance is the key issue for development of sodium ion batteries. Due to the high structural stability, facile reaction mechanism and rich structural diversity, phosphate framework materials have attracted increasing attention as promising electrode materials for sodium ion batteries. Herein, we review the latest advances and progresses in the exploration of phosphate framework materials especially related to single-phosphates, pyrophosphates and mixed-phosphates. We provide the detailed and comprehensive understanding of structure-composition-performance relationship of materials and try to show the advantages and disadvantages of the materials for use in SIBs. In addition, some new perspectives about phosphate framework materials for SIBs are also discussed. Phosphate framework materials will be a competitive and attractive choice for use as electrodes in the next-generation of energy storage devices.

Structural insights of the ssDNA binding site in the multifunctional endonuclease AtBFN2 from Arabidopsis thaliana.

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Tsung-Fu Yu

Full Text Available The multi S1/P1 nuclease AtBFN2 (EC 3.1.30.1 encoded by the Arabidopsis thaliana At1g68290 gene is a glycoprotein that digests RNA, ssDNA, and dsDNA. AtBFN2 depends on three zinc ions for cleaving DNA and RNA at 3'-OH to yield 5'-nucleotides. In addition, AtBFN2's enzymatic activity is strongly glycan dependent. Plant Zn(2+-dependent endonucleases present a unique fold, and belong to the Phospholipase C (PLC/P1 nuclease superfamily. In this work, we present the first complete, ligand-free, AtBFN2 crystal structure, along with sulfate, phosphate and ssDNA co-crystal structures. With these, we were able to provide better insight into the glycan structure and possible enzymatic mechanism. In comparison with other nucleases, the AtBFN2/ligand-free and AtBFN2/PO4 models suggest a similar, previously proposed, catalytic mechanism. Our data also confirm that the phosphate and vanadate can inhibit the enzyme activity by occupying the active site. More importantly, the AtBFN2/A5T structure reveals a novel and conserved secondary binding site, which seems to be important for plant Zn(2+-dependent endonucleases. Based on these findings, we propose a rational ssDNA binding model, in which the ssDNA wraps itself around the protein and the attached surface glycan, in turn, reinforces the binding complex.

Label-Free and Real-Time Monitor of Binding and Dissociation Processes between Protein A and Swine IgG by Oblique-Incidence Reflectivity Difference Method

International Nuclear Information System (INIS)

He Li-Ping; Liu Shuang; Dai Jun; Lu Hui-Bin; Jin Kui-Juan; Yang Guo-Zhen; Wu Lin; Liu Guo-Zhen; Wei Han-Fu

2015-01-01

Life science has a need for detection methods that are label-free and real-time. In this paper, we have selected staphylococcal protein A (SPA) and swine immunoglobulin G (IgG), and monitor the bindings between SPA and swine IgG with different concentrations, as well as the dissociations of SPA-swine IgG complex in different pH values of phosphate buffer by oblique-incidence reflectivity difference (OIRD) in a label-free and real-time fashion. We obtain the ON and OFF reaction dynamic curves corresponding to the bindings and dissociations of SPA and swine IgG. Through our analysis of the experimental results, we have been able to obtain the damping coefficients and the dissociation time of SPA and swine IgG for different pH values of the phosphate buffer. The results prove that the OIRD technique is a competing method for monitoring the dynamic processes of biomolecule interaction and achieving the quantitative information of reaction kinetics. (general)

Photoelectron spectroscopy of phosphites and phosphates

Energy Technology Data Exchange (ETDEWEB)

Chattopadhyay, S.; Findley, G.L.; McGlynn, S.P.

1981-01-01

The ultraviolet photoelectron spectra (UPS) of trimethyl and triethyl phosphite, trimethyl and triethyl phosphate and four substituted phosphates are presented. Assignments are based on analogies to the UPS of phosphorus trichloride and phosphoryl trichloride and are substantiated by CNDO/2 computations. The mechanisms of P-O (axial) bond formation is discussed.

Phosphate uptake kinetics for four species of submerged freshwater macrophytes measured by a 33P phosphate radioisotope technique

DEFF Research Database (Denmark)

Christiansen, Nina Høj; Andersen, Frede Østergaard; Jensen, Henning S.

2016-01-01

Phosphate (Pi) uptake kinetics were determined in shoot and root tissues for four freshwater macrophyte species, Littorella uniflora, Potamogeton perfoliatus, Myriophyllum alterniflorum and Elodea canadensis, using a radioactive 33P phosphate technique. Collection of plant material in the oligotr...

The variable charge of andisols as affected by nanoparticles of rock phosphate and phosphate solubilizing bacteria

Science.gov (United States)

Arifin, M.; Nurlaeny, N.; Devnita, R.; Fitriatin, B. N.; Sandrawati, A.; Supriatna, Y.

2018-02-01

Andisols has a great potential as agriculture land, however, it has a high phosphorus retention, variable charge characteristics and high value of zero net charge or pH0. The research is aimed to study the effects of nanoparticles of rock phosphate (NPRP) and biofertilizer (phosphate solubilizing bacteria/PSB) on soil pH, pHo (zero point of charge, ZPC) and organic-C in one subgroup of Andisols, namely Acrudoxic Durudands, Ciater Region West Java. The research was conducted from October 2016 to February 2017 in Soil Physics Laboratory and Laboratory of Soil Chemistry and Fertility, Soil Science Department, Faculty of Agriculture, Universitas Padjadjaran. This experiment used a completely randomized factorial design, consisting of two factors and three replications. The first factor was nanoparticles of rock phosphate consist of 4 doses 0; 25; 50 and 75 g/1 kg soil and the second factor was biofertilizer dose consist of g/1 kg soil and without biofertilizer. Total treatment combinations were 8 with 3 replications, so there were 24 experimental plots. The results showed that in general NPRR and biofertilizer will decrease the value of soil pH throughout the incubation periods. There is an interaction between nanoparticles of rock phosphate and biofertilizer in decreasing pHo in the first month of incubation, but after 4-month incubation period, NPRP increased. Interaction between 75 g nanoparticles of rock phosphate with 1 g biofertilizer/1 kg soil in fourth months of incubation decreased soil organic-C to 3.35%.

Study of the binding of {sup 114m}In radiotracer to human serum components by ultrafiltration and chromatography

Energy Technology Data Exchange (ETDEWEB)

Hulle, M. van; De Cremer, K.; Cornelis, R. [Ghent Rijksuniversiteit (Belgium). Lab. for Analytical Chemistry

2000-10-01

The chemical speciation of indium in serum was studied. Ultrafiltration was used to investigate the influence of several buffer systems on the binding characteristics of indium in serum and to study the association of indium with transferrin and albumin. This was performed by means of batch incubation experiments with a {sup 114m}In tracer. Different buffer systems were investigated. A series of bicarbonate, Tris:HCl and HEPES buffers were found to fit for this purpose. Phosphate buffer was not suitable, as it is capable of disrupting the binding between indium and transferrin. Batch ultrafiltration experiments with {sup 114m}In incubated solutions of transferrin and albumin showed that both proteins are capable of binding indium to a high degree. Three chromatographic techniques (SEC, AEC, AC) were used to study the different chemically active species of indium in serum. It is concluded that next to transferrin, albumin is also responsible for the binding and transport of indium in serum. (orig.)

Systematic search for the Cra-binding promoters using genomic SELEX system.

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Shimada, Tomohiro; Fujita, Nobuyuki; Maeda, Michihisa; Ishihama, Akira

2005-09-01

Cra (or FruR), a global transcription factor with both repression and activation activities, controls a large number of the genes for glycolysis and gluconeogenesis. To get insights into the entire network of transcription regulation of the E. coli genome by Cra, we isolated a set of Cra-binding sequences using an improved method of genomic SELEX. From the DNA sequences of 97 independently isolated DNA fragments by SELEX, the Cra-binding sequences were identified in a total of ten regions on the E. coli genome, including promoters of six known genes and four hitherto-unidentified genes. All six known promoters are repressed by Cra, but none of the activation-type promoters were cloned after two cyles of SELEX, because the Cra-binding affinity to the repression-type promoters is higher than the activation-type promoters, as determined by the quantitative gel shift assay. Of a total of four newly identified Cra-binding sequences, two are associated with promoter regions of the gapA (glyceraldehyde 3-phosphate dehydrogenase) and eno (enolase) genes, both involved in sugar metabolism. The regulation of newly identified genes by Cra was confirmed by the in vivo promoter strength assay using a newly developed TFP (two-fluorescent protein) vector for promoter assay or by in vitro transcription assay in the presence of Cra protein.

Uranium and heavy metals in phosphate fertilizers

International Nuclear Information System (INIS)

Khater, A.E.M.

2008-01-01

Agricultural applications of chemical fertilizers are a worldwide practice. The specific activity of uranium-238 and heavy metals in phosphate fertilizers depends on the phosphate ore from which the fertilizer produced and on the chemical processing of the ore. Composite phosphate fertilizers samples where collected and the uranium-238 specific activity, in Bq/kg, and As, Cd, Cu, Pb, Se concentration, in ppm, were measured. The annual addition of these elements in soil due to fertilization were calculated and discussed. (author)(tk)

Uranium and heavy metals in phosphate fertilizers

International Nuclear Information System (INIS)

Khater, Ashraf E.M.; King Saud University, Riyadh

2008-01-01

Full text: Agricultural applications of chemical fertilizers are a worldwide practice. The specific activity of uranium-238 and heavy metals in phosphate fertilizers depends on the phosphate ore from which the fertilizer produced and on the chemical processing of the ore. Composite phosphate fertilizers samples were collected and the uranium-238 specific activity, in Bq/kg, and As, Cd, Cu, Pb, Se concentration were measured. The annual addition of these elements in soil due to soil fertilization were calculated and discussed. (author)

Availability of native and added phosphates for the soil

International Nuclear Information System (INIS)

Scivittaro, W.B.; Boaretto, A.E.; Muraoka, T.

1995-01-01

In superficial composite samples of two Red-Yellow Latosols with different physical and chemical properties, analyses were carried out on inorganic form of phosphorus as well as the availability of native and added phosphates. The method applied was soil phosphorus fractionation associated with isotopic dilution technique ( 32 P). The samples were taken from pots containing soils incubated for a month with fluid phosphatic fertilizers (phosphoric acid and 10-30-00 suspension) and solid phosphatic fertilizers (mono ammonium phosphate and triple superphosphate), at the rate of 210 mg P 2 O 5 /kg of soil. A control treatment was included. In both soils the availability of inorganic phosphorus fractions decreased at the following order: H 2 O-P > Al-P > Fe-P > CA-P > occluded-P. The water soluble and aluminium phosphates represented the main source of available P for the newly fertilizer, the iron phosphates were also an important source of available phosphorus. The soil phosphorus fixing capacity influenced the availability of native and added phosphates. (author). 17 refs, 3 tabs

From dirt to industrial applications: Pseudomonas putida as a Synthetic Biology chassis for hosting harsh biochemical reactions.

Science.gov (United States)

Nikel, Pablo I; Chavarría, Max; Danchin, Antoine; de Lorenzo, Víctor

2016-10-01

The soil bacterium Pseudomonas putida is endowed with a central carbon metabolic network capable of fulfilling high demands of reducing power. This situation arises from a unique metabolic architecture that encompasses the partial recycling of triose phosphates to hexose phosphates-the so-called EDEMP cycle. In this article, the value of P. putida as a bacterial chassis of choice for contemporary, industrially-oriented metabolic engineering is addressed. The biochemical properties that make this bacterium adequate for hosting biotransformations involving redox reactions as well as toxic compounds and intermediates are discussed. Finally, novel developments and open questions in the continuous quest for an optimal microbial cell factory are presented at the light of current and future needs in the area of biocatalysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adaptation of red cell enzymes and intermediates in metabolic disorders.

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Goebel, K M; Goebel, F D; Neitzert, A; Hausmann, L; Schneider, J

1975-01-01

The metabolic activity of the red cell glycolytic pathway hexose monophosphate shunt (HMP) with dependent glutathione system was studied in patients with hyperthyroidism (n = 10), hyperlipoproteinemia (n = 16), hypoglycemia (n = 25) and hyperglycemia (n = 23). In uncontrolled diabetics and patients with hyperthyroidism the mean value of glucose phosphate isomerase (GPI), glucose-6-phosphate dehydrogenase (G-6-PD), glutathione reductase (GR) was increased, whereas these enzyme activities were reduced in patients with hypoglycemia. Apart from a few values of hexokinase (HK) which were lower than normal the results in hyperlipoproteinemia patients remained essentially unchanged, including the intermediates such as 2,3-diphosphoglycerate (2,3-DPG), adenosine triphosphate (ATP) and reduced glutathione (GSH). While increased rates of 2,3-DPG and ATP in hypoglycemia patients were obtained, these substrates were markedly reduced in diabetics.

Regularities in Low-Temperature Phosphatization of Silicates

Science.gov (United States)

Savenko, A. V.

2018-01-01

The regularities in low-temperature phosphatization of silicates are defined from long-term experiments on the interaction between different silicate minerals and phosphate-bearing solutions in a wide range of medium acidity. It is shown that the parameters of the reaction of phosphatization of hornblende, orthoclase, and labradorite have the same values as for clayey minerals (kaolinite and montmorillonite). This effect may appear, if phosphotization proceeds, not after silicate minerals with a different structure and composition, but after a secondary silicate phase formed upon interaction between silicates and water and stable in a certain pH range. Variation in the parameters of the reaction of phosphatization at pH ≈ 1.8 is due to the stability of the silicate phase different from that at higher pH values.

Alpha-tocopheryl phosphate: a novel, natural form of vitamin E.

Science.gov (United States)

Gianello, Robert; Libinaki, Roksan; Azzi, Angelo; Gavin, Paul D; Negis, Yesim; Zingg, Jean-Marc; Holt, Phillip; Keah, Hooi-Hong; Griffey, Annike; Smallridge, Andrew; West, Simon M; Ogru, Esra

2005-10-01

We have detected alpha-tocopheryl phosphate in biological tissues including liver and adipose tissue, as well as in a variety of foods, suggesting a ubiquitous presence in animal and plant tissue. Alpha-tocopheryl phosphate is a water-soluble molecule that is resistant to both acid and alkaline hydrolysis, making it undetectable using standard assays for vitamin E. A new method was therefore developed to allow the extraction of both alpha-tocopheryl phosphate and alpha-tocopherol from a single specimen. We used ESMS to detect endogenous alpha-tocopheryl phosphate in biological samples that also contained alpha-tocopherol. Due to the significance of these findings, further proof was required to unequivocally demonstrate the presence of endogenous alpha-tocopheryl phosphate in biological samples. Four independent methods of analysis were examined: HPLC, LCMS, LCMS/MS, and GCMS. Alpha-tocopherol phosphate was identified in all instances by comparison between standard alpha-tocopheryl phosphate and extracts of biological tissues. The results show that alpha-tocopheryl phosphate is a natural form of vitamin E. The discovery of endogenous alpha-tocopheryl phosphate has implications for the expanding knowledge of the roles of alpha-tocopherol in biological systems.