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Sample records for monodentate sulfate ligand

  1. Riding the Wave of Monodentate Ligand Revival: From the A/B Concept to Noncovalent Interactions.

    Science.gov (United States)

    Pignataro, Luca; Gennari, Cesare

    2016-12-01

    The rediscovery of chiral monodentate ligands made in the period 1999-2003 had important consequences in enantioselective transition-metal catalysis, such as the introduction of the A/B concept (i.e., use of monodentate ligand mixtures) and, later, a renewed interest in supramolecular ligands capable of ligand-ligand and ligand-substrate interactions. This Personal Account summarizes the contributions made by our research group in this area in the period 2004-2015, which reflect the abovementioned developments. Within this area, we introduced some original concepts, such as 1) the use of chiral tropos ligand mixtures; 2) the development of new strategies to maximize heterocomplex formation from combinations of simple monodentate ligands; 3) the investigation of new ligand-ligand interactions to achieve selective heterocomplex formation; and 4) the development of highly efficient and synthetically accessible supramolecular ligands. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Recent advances in catalytic asymmetric hydrogenation:Renaissance of the monodentate phosphorus ligands

    Institute of Scientific and Technical Information of China (English)

    GUO Hongchao; DING Kuiling; DAI Lixin

    2004-01-01

    The history for the development of chiral phosphorus ligands in catalytic asymmetric hydrogenation is briefly highlighted. This review focuses on the recent advances in the synthesis of the monodentate phosphorus ligands and their applications in catalytic asymmetric hydrogenation. The examples highlighted in this article clearly demonstrated the importance and advantages of monodentate phosphorus ligands, which had been ignored for 30 a and experienced a renaissance at the very beginning of this millennium, particularly in the area of asymmetric hydrogenation.

  3. Design, testing and kinetic analysis of bulky monodentate phosphorus ligands in the Mizoroki-Heck reaction

    NARCIS (Netherlands)

    Dodds, D.L.; Boele, M.D.K.; van Strijdonck, G.P.F.; de Vries, J.G.; van Leeuwen, P.W.N.M.; Kamer, P.C.J.

    2012-01-01

    A series of new monodentate phosphane ligands 2 have been evaluated in the Mizoroki-Heck arylation reaction of iodobenzene and styrene and compared with our previously reported ligands, 1, 3 and 4. The concept of rational ligand design is discussed, and we describe how the performance of this new li

  4. Design, Testing and Kinetic Analysis of Bulky Monodentate Phosphorus Ligands in the Mizoroki-Heck Reaction

    NARCIS (Netherlands)

    Dodds, Deborah L.; Boele, Maarten D. K.; van Strijdonck, Gino P. F.; de Vries, Johannes G.; van Leeuwen, Piet W. N. M.; Kamer, Paul C. J.

    2012-01-01

    A series of new monodentate phosphane ligands 2 have been evaluated in the MizorokiHeck arylation reaction of iodobenzene and styrene and compared with our previously reported ligands, 1, 3 and 4. The concept of rational ligand design is discussed, and we describe how the performance of this new lig

  5. Design, Testing and Kinetic Analysis of Bulky Monodentate Phosphorus Ligands in the Mizoroki-Heck Reaction

    NARCIS (Netherlands)

    Dodds, Deborah L.; Boele, Maarten D. K.; van Strijdonck, Gino P. F.; de Vries, Johannes G.; van Leeuwen, Piet W. N. M.; Kamer, Paul C. J.

    A series of new monodentate phosphane ligands 2 have been evaluated in the MizorokiHeck arylation reaction of iodobenzene and styrene and compared with our previously reported ligands, 1, 3 and 4. The concept of rational ligand design is discussed, and we describe how the performance of this new

  6. Design, testing and kinetic analysis of bulky monodentate phosphorus ligands in the Mizoroki-Heck reaction

    NARCIS (Netherlands)

    Dodds, D.L.; Boele, M.D.K.; van Strijdonck, G.P.F.; de Vries, J.G.; van Leeuwen, P.W.N.M.; Kamer, P.C.J.

    2012-01-01

    A series of new monodentate phosphane ligands 2 have been evaluated in the Mizoroki-Heck arylation reaction of iodobenzene and styrene and compared with our previously reported ligands, 1, 3 and 4. The concept of rational ligand design is discussed, and we describe how the performance of this new

  7. Rhodium-Catalyzed Asymmetric Conjugate Additions of Boronic Acids Using Monodentate Phosphoramidite Ligands

    NARCIS (Netherlands)

    -G Boiteau, J.; Imbos, R.; J. Minnaard, A.; Feringa, B.L.

    2003-01-01

    Monodentate phosphoramidites have been used for the first time as chiral ligands in the Rh-catalyzed enantioselective conjugate addition of arylboronic acids to enones, unsaturated esters, lactones, and nitro alkenes. High reaction rates and ee’s up to 89% have been obtained.

  8. First Examples of Improved Catalytic Asymmetric C-C Bond Formation Using the Monodentate Ligand Combination Approach

    NARCIS (Netherlands)

    Duursma, Ate; Hoen, Rob; Schuppan, Julia; Hulst, Ron; Minnaard, Adriaan J.; Feringa, Bernard

    2003-01-01

    Using a combination of chiral monodentate phosphoramidite ligands in the rhodium-catalyzed conjugate addition of boronic acids to three different substrates, we have shown for the first time that the ligand combination approach is applicable for C-C bond formation. Chiral catalysts based on hetero-c

  9. Application of monodentate secondary phosphine oxides, a new class of chiral ligands, in Ir(I)-catalyzed asymmetric imine hydrogenation

    NARCIS (Netherlands)

    Jiang, X.B.; Minnaard, A.J.; Hessen, B.; Feringa, B.L.; Duchateau, A.L.L.; Andrien, J.G.O.; Boogers, J.A.F.; de Vries, J.G.; L. L. Duschateau, A.

    2003-01-01

    Secondary phosphine oxides were prepared from R1PCl2 and R2MgBr, followed by hydrolysis. They were obtained in an enantiopure form by preparative chiral HPLC. These new monodentate ligands were tested in the iridium-catalyzed hydrogenation of imines at 25 bar. Enantioselectivities up to 76% were obt

  10. Pd-catalyzed amidation of aryl chlorides using monodentate biaryl phosphine ligands: a kinetic, computational, and synthetic investigation.

    Science.gov (United States)

    Ikawa, Takashi; Barder, Timothy E; Biscoe, Mark R; Buchwald, Stephen L

    2007-10-31

    We present results on the amidation of aryl halides and sulfonates utilizing a monodentate biaryl phosphine-Pd catalyst. Our results are in accord with a previous report that suggests that the formation of kappa(2)-amidate complexes is deleterious to the effectiveness of a catalyst for this transformation and that their formation can be prevented by the use of appropriate bidentate ligands. We now provide data that suggest that the use of certain monodentate ligands can also prevent the formation of the kappa(2)-amidate complexes and thereby generate more stable catalysts for the amination of aryl chlorides. Furthermore, computational studies shed light on the importance of the key feature(s) of the biaryl phosphines (a methyl group ortho to the phosphorus center) that enable the coupling to occur. The use of ligands that possess a methyl group ortho to the phosphorus center allows a variety of aryl and heteroaryl chlorides with various amides to be coupled in high yield.

  11. Enthalpy of ligand substitution in cis organopalladium complexes with monodentate ligands.

    Science.gov (United States)

    Salas, Gorka; Casares, Juan A; Espinet, Pablo

    2009-10-21

    The enthalpy for the substitution reaction cis-[PdRf(2)(THF)(2)] + 2 L -->cis-[PdRf(2)L(2)] + 2THF (THF = tetrahydrofuran) has been measured in THF by calorimetric methods for Rf = 3,5-dichloro-2,4,6-trifluorophenyl, L = PPh(3), AsPh(3), SbPh(3), PMePh(2), PCyPh(2), PMe(3), AsMePh(2), or L(2) = dppe (1,2-bis(diphenylphosphino)ethane), dppf (1,1'-bis(diphenylphosphino)ferrocene). The values determined show that the substitution enthalpy has a strong dependence on the electronic and steric properties of the ligand. The study of the consecutive substitution reactions cis-[PdRf(2)(THF)(2)] + L -->cis-[PdRf(2)L(THF)] + THF, and cis-[PdRf(2)L(THF)] + L -->cis-[PdRf(2)L(2)] + THF has been carried our for L = PPh(3) and L = PCyPh(2). The first substitution is clearly more favorable for the bulkier leaving ligand, but the second gives practically the same DeltaH value for both cases, indicating that the differences in steric hindrance happen to compensate the electronic differences for both ligands. The X-ray structures of cis-[PdRf(2)(PMePh(2))(2)], cis-[PdRf(2)(dppe)] and cis-[PdRf(2)(dppf)] are reported.

  12. Preparation and photoluminescence enhancement in terbium(III ternary complexes with β-diketone and monodentate auxiliary ligands

    Directory of Open Access Journals (Sweden)

    Devender Singh

    2016-12-01

    Full Text Available A series of new solid ternary complexes of terbium(III ion based on β-diketone ligand acetylacetone (acac and monodentate auxiliary ligands (aqua/urea/triphenylphosphineoxide/pyridine-N-oxide had been prepared. The structural characterizations of synthesized ternary compounds were studied by means of elemental analysis, infrared (IR, and proton nuclear magnetic resonance (NMR spectral techniques. The optical characteristics were investigated with absorption as well as photoluminescence spectroscopy. Thermal behavior of compounds was examined by TGA/DTA analysis and all metal complexes were found to have good thermal stability. The luminescence decay time of complexes were also calculated by monitoring at emission wavelength corresponding to 5D4 → 7F5 transition. A comparative inspection of the luminescent behavior of prepared ternary compounds was performed in order to determine the function of auxiliary ligands in the enhancement of luminescence intensity produced by central terbium(III ion. The color coordinates values suggested that compounds showed bright green emission in visible region in electromagnetic spectrum. Complexes producing green light could play a significant role in the fabrication of efficient light conversion molecular devices for display purposes and lightning systems.

  13. Synthesis of meta-substituted monodentate phosphinite ligands and implication in hydroformylation

    Indian Academy of Sciences (India)

    SATEJ S DESHMUKH; SHAHAJI R GAIKWAD; SWECHCHHA PANDEY; PRAMOD S MALI; SAMIR H CHIKKALI

    2017-08-01

    Synthesis of meta-substituted phosphinite ligands 3,3' (methoxyphosphanediyl) bis (N,Ndiethylaniline) (4a) and methoxybis(3-methoxyphenyl)phosphane (4b), in high yields, has been demonstrated. Typical phosphorus chemical shift between 110–120 ppm, appearance of methoxy protons and corresponding carbon, as well as ESI-MS spectra unambiguously confirmed the existence of phosphinite ligands 4a and 4b. To demonstrate the synthetic usefulness of 4a and 4b, these ligands were tested in the rhodium catalyzed hydroformylation of 1-octene. The diethylamine substituted ligand 4a was found to be highly active, whereas4bwas less reactive but revealed slightly better regioselectivity of 62% under optimized conditions.Additionally, 4a and 4b were found to catalyze the hydroformylation of styrene, 1-undecenol and 1,1-disubstituted functionalolefin, methyl methacrylate. Both the ligands displayed excellent conversion of styrene, and 4b revealed an excellent branch selectivity of 75%. Although 1-undecenol proved to be amenable to hydroformylation (85–90% conversion to aldehyde), both the ligands failed to discriminate between the linear and branched products. Substrate methyl methacrylate proved to be highly challenging and reduced conversion (between 33–42%) was observed under optimized conditions. Ligand 4a was found to be highly selective towards linear aldehyde (81% linear selectivity).

  14. Instant Ligand Libraries. Parallel Synthesis of Monodentate Phosphoramidites and in Situ Screening in Asymmetric Hydrogenation

    NARCIS (Netherlands)

    Lefort, Laurent; Boogers, Jeroen A.F.; Vries, André H.M. de; Vries, Johannes G. de

    2004-01-01

    Chiral phosphoramidites have been identified as excellent ligands for various metal-catalyzed enantioselective transformations. Taking advantage of their easy preparation and modular nature, we designed a fully automated protocol for the parallel preparation of a library of 32 phosphoramidites and i

  15. Enantioselective Rh-catalyzed hydrogenation of N-formyl dehydroamino esters with monodentate phosphoramidite ligands

    NARCIS (Netherlands)

    Panella, L; Aleixandre, AM; Kruidhof, GJ; Robertus, J; Feringa, BL; de Vries, JG; Minnaard, AJ; Aleixandre, Alicia Marco; Kruidhof, Gerlof J.; Feringa, Bernard

    2006-01-01

    Enantioselectivities up to > 99% ee were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using morrodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with

  16. Luminescent single-ion magnets from Lanthanoid(III) complexes with monodentate ketone ligands

    Energy Technology Data Exchange (ETDEWEB)

    Kanetomo, Takuya; Ishida, Takayuki, E-mail: takayuki.ishida@uec.ac.jp [Department of Engineering Science, The University of Electro-Communications, Tokyo (Japan)

    2016-02-01

    We synthesized [Ln{sup III}(hfac){sub 3}(H{sub 2}O)(L)] (abbreviated as Ln-L; Ln = Gd, Tb, Eu; L = DTBK (di-t-butyl ketone), BP (benzophenone)), in which the carbonyl oxygen atom was coordinated to the Ln ion center, despite of such bulky substituents. Their crystal structures were determined by means of X-ray diffraction study. Gd-DTBK is completely isomorphous to the di-t-butyl nitroxide derivative and accordingly can be regarded as a model with the ligand spin masked. The ac magnetic susceptibility measurements on Tb-DTBK and -BP showed frequency dependence, characteristic of single-ion magnets. They also displayed photoluminescence in the solid state at room temperature. The quantum yields of the luminescence of Tb-DTBK and -BP (λ{sub ex} = 360 nm) were improved to 57 and 35%, respectively, from that of the starting material [TbI{sup III}(hfac){sub 3}(H{sub 2}O){sub 2}] (28% at λ{sub ex} = 370 nm). Similarly, the quantum yields for Eu-DTBK and -BP were 8 and 15%, respectively, with λ{sub ex} = 400 nm, while that of the starting material [EuI{sup III}(hfac){sub 3}(H{sub 2}O){sub 2}] was 4% at λ{sub ex}=400 nm.

  17. Conversion of a monodentate amidinate-germylene ligand into chelating imine-germanate ligands (on mononuclear manganese complexes).

    Science.gov (United States)

    Cabeza, Javier A; García-Álvarez, Pablo; Pérez-Carreño, Enrique; Polo, Diego

    2014-08-18

    The unprecedented transformation of a terminal two-electron-donor amidinate-germylene ligand into a chelating three-electron-donor κ(2)-N,Ge-imine-germanate ligand has been achieved by treating the manganese amidinate-germylene complex [MnBr{Ge((i)Pr2bzam)(t)Bu}(CO)4] (1; (i)Pr2bzam = N,N'-bis(isopropyl)benzamidinate) with LiMe or Ag[BF4]. In these reactions, which afford [Mn{κ(2)Ge,N-GeMe((i)Pr2bzam)(t)Bu}(CO)4] (2) and [Mn{κ(2)Ge,N-GeF((i)Pr2bzam)(t)Bu}(CO)4] (3), respectively, the anionic nucleophile, Me(-) or F(-), ends on the Ge atom while an arm of the amidinate fragment migrates from the Ge atom to the Mn atom. In contrast, the reaction of 1 with AgOTf (OTf = triflate) leads to [Mn(OTf){Ge((i)Pr2bzam)(t)Bu}(CO)4] (4), which maintains intact the amidinate-germylene ligand. Complex 4 is very moisture-sensitive, leading to [Mn2{μ-κ(4)Ge2,O2-Ge2(t)Bu2(OH)2O}(CO)8] (5) and [(i)Pr2bzamH2]OTf (6) in wet solvents. In 5, a novel digermanate(II) ligand, [(t)Bu(OH)GeOGe(OH)(t)Bu](2-), doubly bridges two Mn(CO)4 units. The structures of 1-6 have been characterized by spectroscopic (IR, NMR) and single-crystal X-ray diffraction methods.

  18. Synthesis, characterization, DFT calculation and biological activity of square-planar Ni(II) complexes with tridentate PNO ligands and monodentate pseudohalides. Part II.

    Science.gov (United States)

    Milenković, Milica; Pevec, Andrej; Turel, Iztok; Vujčić, Miroslava; Milenković, Marina; Jovanović, Katarina; Gligorijević, Nevenka; Radulović, Siniša; Swart, Marcel; Gruden-Pavlović, Maja; Adaila, Kawther; Cobeljić, Božidar; Anđelković, Katarina

    2014-11-24

    Three square-planar complexes of Ni(II) with condensation derivative of 2-(diphenylphosphino)benzaldehyde and 4-phenylsemicarbazide and monodentate pseudohalides have been synthesized and characterized on the basis of the results of X-ray, NMR and IR spectroscopy and elemental analysis. Investigated complexes exhibited moderate antibacterial and cytotoxic activity. The most pronounced cytotoxic activity (in the range of cisplatin) to HeLa cell line was observed for ligand and all the complexes. Azido complex and ligand induced concentration dependent cell cycle arrest in the S phase, as well as decrease of percentage of cells in G1 phase, without significant increase of apoptotic fraction of cells. The interaction of the azido complex and ligand with CT-DNA results in changes in UV-Vis spectra typical for non-covalent bonding. The observed intrinsic binding constant of azido complex-CT-DNA and ligand-CT-DNA were 3.22 × 10(5) M(-1) and 2.79 × 10(5) M(-1). The results of DNA cleavage experiments showed that azido complex nicked supercoiled plasmid DNA.

  19. Rhenium(V) and technetium(V) nitrido complexes with mixed tridentate π-donor and monodentate π-acceptor ligands.

    Science.gov (United States)

    Boschi, Alessandra; Cazzola, Emiliano; Uccelli, Licia; Pasquali, Micol; Ferretti, Valeria; Bertolasi, Valerio; Duatti, Adriano

    2012-03-01

    Mixed-ligand [M(N)(SNS)(PPh(3))] complexes (M = Tc, Re) (1, 2) were prepared by reaction of the precursor [M(N)Cl(2)(PPh(3))(2)] with ligand 2,2'-dimercaptodiethylamine [H(2)SNS = NH(CH(2)CH(2)SH)(2)] in refluxing dichloromethane/ethanol mixtures. In these compounds, 2,2'-dimercaptodiethylamine acts as a dianionic tridentate chelating ligand bound to the [M≡N](2+) group through the two π-donor deprotonated sulfur atoms and the protonated amine nitrogen atom. Triphenylphosphine completes the coordination sphere, acting as a monodentate ligand. [M(N)(NS(2))(PPh(3))] complexes can assume two different isomeric forms depending on the syn and anti orientations of the hydrogen atom bound to the central nitrogen atom of the SNS ligand with respect to the M≡N moiety. X-ray crystallography of the syn isomer of complex 2 demonstrated that it has a distorted trigonal bipyramidal geometry with the nitrido group and the two sulfur atoms defining the equatorial plane, the phosphorus atom of the monophosphine and the protonated amine nitrogen of the tridentate ligand spanning the two reciprocal trans positions along the axis perpendicular to the trigonal plane. Synthesis of the analogous Tc derivatives with tris(2-cyanoethyl)phosphine, [Tc(N)(SNS)(PCN)] [(PCN = P(CH(2)CH(2)CN)(3)], required the preliminary preparation of the new precursor [Tc(N)(PCN)(2)Cl(2)](2) (3), which was prepared by reacting [n-NBu(4)][Tc(N)Cl(4)] with a high excess of PCN. The crystal structure of compound 3 consists of a noncrystallographic centrosymmetric dimer of Tc(V) nitrido complexes having an octahedral geometry. In this arrangement, the apical positions are occupied by two tris(2-cyanoethyl)phosphine groups and the equatorial positions by the nitrido group whereas the two Cl(-) anions and one cyano ligand belong to the other octahedral component of the dimer. By reacting the new precursor [Tc(N)(PCN)(2)Cl(2)](2) with the ligand H(2)SNS the complex [Tc(N)(SNS)(PCN)] (5) was finally obtained in

  20. Pregnenolone Sulfate: From Steroid Metabolite to TRP Channel Ligand

    Directory of Open Access Journals (Sweden)

    Christian Harteneck

    2013-09-01

    Full Text Available Pregnenolone sulfate is a steroid metabolite with a plethora of actions and functions. As a neurosteroid, pregnenolone sulfate modulates a variety of ion channels, transporters, and enzymes. Interestingly, as a sulfated steroid, pregnenolone sulfate is not the final- or waste-product of pregnenolone being sulfated via a phase II metabolism reaction and renally excreted, as one would presume from the pharmacology textbook knowledge. Pregnenolone sulfate is also the source and thereby the starting point for subsequent steroid synthesis pathways. Most recently, pregnenolone sulfate has been functionally “upgraded” from modulator of ion channels to an activating ion channel ligand. This review will focus on molecular aspects of the neurosteroid, pregnenolone sulfate, its metabolism, concentrations in serum and tissues and last not least will summarize the functional data.

  1. A Novel Copper(Ⅱ) Coordination Polymer with Figure-of-eight-shaped Channels Occupied by Flexible Monodentate and Bidentate N,N'-bipyrdyl Ligands%A Novel Copper(Ⅱ) Coordination Polymer with Figure-of-eight-shaped Channels Occupied by Flexible Monodentate and Bidentate N,N'-bipyrdyl Ligands

    Institute of Scientific and Technical Information of China (English)

    PAN Peng-Bin; ZHANG Xin; YANG Jin-Xia; YIN Pei-Xiu; YAO Yuan-Gen

    2011-01-01

    A copper(Ⅱ) coordination polymer, [Cu3(HOA)2(bpp)4]n (1, HnOA = 3,3',4,4'- oxidiphthalic acid, bpp = 1,3-bis(4-pyridyl) propane), has been hydrothermally synthesized. The crystal structure is of monoclinic, space group P21/c with a = 11.544(3), b = 16.129(4), c = 21.181 (6) A, β = 98.848(5), V= 3897.0(2) A3, C84018N8H70Cu3, Mr = 1670.13, Z = 2, De = 1.423 g/cm^3, F(000) = 1722, μ = 0.887 mm^-1, R = 0.0878 and wR = 0.2583 for 8496 observed reflections (I 〉 2σ(I)). Single-crystal X-ray structural analysis reveals that 1 is a three-dimensional (3D) framework based on a two-dimensional (2D) mesomeric layer of alternating left- and fight-handed helical chains. The monodentate terminal and bidentate bridging bpp ligands in the same conformation are all encapsulated in the figure-of-eight-shaped channels, thus further stabilizing the whole three-dimensional framework.

  2. Polycations XX: New Monodentate Cationic Ligands and Their Coordination with Ruthenium for the Construction of Complexes Expressing Enhanced Interaction with DNA

    Directory of Open Access Journals (Sweden)

    Leslie Babukutty

    2012-01-01

    Full Text Available Prior investigations from this laboratory concerned with the preparation of new types of organic cations for a variety of biological and nonbiological applications have been extended to the preparation of cation-bearing ligands with nitrogen coordinating sites for use in complexation reactions with ruthenium cores. The syntheses of new cationic ligands as well as ruthenium complexes bearing them are reported here. The introduction of these new types of ligands is intended to provide to the complexes an enhanced ability to interact with DNA, and thereby to have the potential to be enhanced antitumor agents. Preliminary observations of their interactions with DNA are presented.

  3. Potentiometric and spectrometric study: Copper(II), nickel(II) and zinc(II) complexes with potentially tridentate and monodentate ligands

    Indian Academy of Sciences (India)

    R N Patel; Nripendra Singh; R P Shrivastava; K K Shukla; P K Singh

    2002-04-01

    Equilibrium and solution structural study of mixed-metal-mixed-ligand complexes of Cu(II), Ni(II) and Zn(II) with L-cysteine, L-threonine and imidazole are conducted in aqueous solution by potentiometry and spectrophotometry. Stability constants of the binary, ternary and quaternary complexes are determined at 25 ± 1 ° C and in = 0.1 M NaClO4. The results of these two methods are made selfconsistent, then rationalized assuming an equilibrium model including the species H3A, H2A, A, BH, B, M(OH), M(OH)2, M(A), MA(OH), M(B), M(A)(B), M2(A)2(B), M2(A)2(B-H), M1M2(A)2(B) and M1M2(A)2(B-H) (where the charges of the species have been ignored for the sake of simplicity) (A = L-cysteine, L-threonine, salicylglycine, salicylvaline and BH = imidazole). Evidence of the deprotonation of BH ligand is available at alkaline H. N1H deprotonation of the bidentate coordinated imidazole ligand in the binuclear species at H > 7.0 is evident from spectral measurements. Stability constants of binary M(A), M(B) and ternary M(A)(B), complexes follow the Irving-Williams order.

  4. Preparation and Investigation of Monodentate and Bridging Pyrazole Complexes

    Science.gov (United States)

    Evans, Wynne

    2004-01-01

    Complexes of pyrazole-derived ligands are very popular due to the ability of the pyrazolato anion to form bridged polymetallic compounds in which the metals are held close enough to react with small molecules or facilitate magnetic exchange. The preparation of monodentate pyrazole and 3,5-dimethylpyrazole (DMHpz) nickel species and the…

  5. Structure of a dinuclear cadmium complex with 2,2′-bipyridine, monodentate nitrate and 3-carboxy-6-methylpyridine-2-carboxylate ligands: intramolecular carbonyl(lone pair...π(ring and nitrate(π...π(ring interactions

    Directory of Open Access Journals (Sweden)

    Juan Granifo

    2015-08-01

    Full Text Available The centrosymmetric dinuclear complex bis(μ-3-carboxy-6-methylpyridine-2-carboxylato-κ3N,O2:O2;κ3O2:N,O2-bis[(2,2′-bipyridine-κ2N,N′(nitrato-κOcadmium] methanol monosolvate, [Cd2(C8H6NO42(NO32(C10H8N22]·CH3OH, was isolated as colourless crystals from the reaction of Cd(NO32·4H2O, 6-methylpyridine-2,3-dicarboxylic acid (mepydcH2 and 2,2′-bipyridine in methanol. The asymmetric unit consists of a CdII cation bound to a μ-κ3N,O2:O2-mepydcH− anion, an N,N′-bidentate 2,2′-bipyridine group and an O-monodentate nitrate anion, and is completed with a methanol solvent molecule at half-occupancy. The Cd complex unit is linked to its centrosymmetric image through a bridging mepydcH− carboxylate O atom to complete the dinuclear complex molecule. Despite a significant variation in the coordination angles, indicating a considerable departure from octahedral coordination geometry about the CdII atom, the Cd—O and Cd—N distances in this complex are surprisingly similar. The crystal structure consists of O—H...O hydrogen-bonded chains parallel to a, further bound by C—H...O contacts along b to form planar two-dimensional arrays parallel to (001. The juxtaposed planes form interstitial columnar voids that are filled by the methanol solvent molecules. These in turn interact with the complex molecules to further stabilize the structure. A search in the literature showed that complexes with the mepydcH− ligand are rare and complexes reported previously with this ligand do not adopt the μ-κ3 coordination mode found in the title compound.

  6. Synthesis, Spectroscopic, and Electrochemical Studies on Some New Copper(II Complexes Containing 2-{[(Z-Phenyl (Pyridine-2-yl Methylidene] Amino}Benzenethiol and Monodentate Ligands

    Directory of Open Access Journals (Sweden)

    S. P. Rawat

    2014-01-01

    Full Text Available Five new mononuclear copper(II complexes, namely, [Cu(L(ImH]·ClO41; [Cu(L(Me-ImH]·ClO42; [Cu(L(Et-ImH]·ClO43; [Cu(L(2-benz-ImH]·ClO44; [Cu(L(benz-ImH]·ClO45, where HL = 2-{[(Z-phenyl (pyridine-2-yl methylidene] amino} benzenethiol; ImH = Imidazole; Me-ImH = Methy-limidazole; Et-ImH = Ethyl-imidazole; 2-benz-ImH = 2-methyl-benzimidazole; benz-ImH = benz-imidazole, have been synthesized and characterized by various physicochemical and spectroscopic techniques. Magnetic moments, electronic spectra, and EPR spectra of the complexes suggested a square planar geometry around Cu(II ion. The synthesized HL ligand behaves as monobasic tridentate Schiff base bound with the metal ion in a tridentate manner, with N2S donor sites of the pyridine-N, azomethine-N, and benzenethiol-S atoms. The redox behaviour of the copper complexes has been studied by cyclic voltammetry. Superoxide dismutase activity of these complexes has been revealed to catalyse the dismutation of superoxide (O2- and IC50 values were evaluated and discussed.

  7. Monodentate phosphoramidites : A breakthrough in rhodium-catalysed asymmetric hydrogenation of olefins

    NARCIS (Netherlands)

    Berg, Michel van den; Minnaard, Adriaan J.; Haak, Robert M.; Leeman, Michel; Schudde, Ebe P.; Meetsma, Auke; de Vries, Andre H.M.; Maljaars, C. Elizabeth P.; Willans, Charlotte E.; Hyett, David; Boogers, Jeroen A.F.; Henderickx, Hubertus; Feringa, Ben L.

    2003-01-01

    Monodentate phosphoramidites based on BINOL or substituted BINOL are excellent ligands for the rhodium-catalysed asymmetric hydrogenation of olefins. Very high enantioselectivities were obtained with MonoPhos (7a) the simplest member of this class, a ligand that is prepared in a single step from BIN

  8. Podocyte injury caused by indoxyl sulfate, a uremic toxin and aryl-hydrocarbon receptor ligand.

    Directory of Open Access Journals (Sweden)

    Osamu Ichii

    Full Text Available Indoxyl sulfate is a uremic toxin and a ligand of the aryl-hydrocarbon receptor (AhR, a transcriptional regulator. Elevated serum indoxyl sulfate levels may contribute to progressive kidney disease and associated vascular disease. We asked whether indoxyl sulfate injures podocytes in vivo and in vitro. Mice exposed to indoxyl sulfate for 8 w exhibited prominent tubulointerstitial lesions with vascular damage. Indoxyl sulfate-exposed mice with microalbuminuria showed ischemic changes, while more severely affected mice showed increased mesangial matrix, segmental solidification, and mesangiolysis. In normal mouse kidneys, AhR was predominantly localized to the podocyte nuclei. In mice exposed to indoxyl sulfate for 2 h, isolated glomeruli manifested increased Cyp1a1 expression, indicating AhR activation. After 8 w of indoxyl sulfate, podocytes showed foot process effacement, cytoplasmic vacuoles, and a focal granular and wrinkled pattern of podocin and synaptopodin expression. Furthermore, vimentin and AhR expression in the glomerulus was increased in the indoxyl sulfate-exposed glomeruli compared to controls. Glomerular expression of characteristic podocyte mRNAs was decreased, including Actn4, Cd2ap, Myh9, Nphs1, Nphs2, Podxl, Synpo, and Wt1. In vitro, immortalized-mouse podocytes exhibited AhR nuclear translocation beginning 30 min after 1 mM indoxyl sulfate exposure, and there was increased phospho-Rac1/Cdc42 at 2 h. After exposure to indoxyl sulfate for 24 h, mouse podocytes exhibited a pro-inflammatory phenotype, perturbed actin cytoskeleton, decreased expression of podocyte-specific genes, and decreased cell viability. In immortalized human podocytes, indoxyl sulfate treatment caused cell injury, decreased mRNA expression of podocyte-specific proteins, as well as integrins, collagens, cytoskeletal proteins, and bone morphogenetic proteins, and increased cytokine and chemokine expression. We propose that basal levels of AhR activity regulate

  9. Sulfated ligands for the copper(I)-catalyzed azide-alkyne cycloaddition.

    Science.gov (United States)

    Wang, Wei; Hong, Senglian; Tran, Andrew; Jiang, Hao; Triano, Rebecca; Liu, Yi; Chen, Xing; Wu, Peng

    2011-10-04

    The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), the prototypical reaction of click chemistry, is accelerated by tris(triazolylmethyl)amine-based ligands. Herein, we compare two new ligands in this family--3-[4-({bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methyl]amino}methyl)-1H-1,2,3-triazol-1-yl]propanol (BTTP) and the corresponding sulfated ligand 3-[4-({bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methyl]amino}methyl)-1H-1,2,3-triazol-1-yl]propyl hydrogen sulfate (BTTPS)--for three bioconjugation applications: 1) labeling of alkyne-tagged glycoproteins in crude cell lysates, 2) labeling of alkyne- or azide-tagged glycoproteins on the surface of live mammalian cells, and 3) labeling of azides in surface proteins of live Escherichia coli. Although BTTPS exhibits faster kinetics than BTTP in accelerating the CuAAC reaction in in vitro kinetic measurements, its labeling efficiency is slightly lower than BTTP in modifying biomolecules with a significant amount of negative charges due to electrostatic repulsion. Nevertheless, the negative charge conferred by the sulfate at physiological conditions significantly reduced the cellular internalization of the coordinated copper(I), thus making BTTPS-Cu(I) a better choice for live-cell labeling. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Asymmetric hydrogenation of quinolines catalyzed by iridium complexes of monodentate BINOL-derived phosphoramidites

    NARCIS (Netherlands)

    Mrsic, Natasa; Lefort, Laurent; Boogers, Jeroen A. F.; Minnaard, Adriaan J.; Feringa, Ben L.; de Vries, Johannes G.; Mršić, Nataša

    The monodentate BINOL-derived phosphoramidite PipPhos is used as ligand for the iridium-catalyzed asymmetric hydrogenation of 2- and 2,6-substituted quinolines. If tri-ortho-tolylphosphine and/or chloride salts are used as additives enantioselectivities are strongly enhanced up to 89%. NMR indicates

  11. Sulfate-bridged dimeric trinuclear copper(II–pyrazolate complex with three different terminal ligands

    Directory of Open Access Journals (Sweden)

    Gellert Mezei

    2016-08-01

    Full Text Available The reaction of CuSO4·5H2O, 4-chloropyrazole (4-Cl-pzH and triethylamine (Et3N in dimethylformamide (DMF produced crystals of diaquahexakis(μ-4-chloropyrazolato-κ2N:N′bis(N,N-dimethylformamidedi-μ3-hydroxido-bis(μ4-sulfato-κ4O:O′:O′′:O′′hexacopper(II N,N-dimethylformamide tetrasolvate dihydrate, [Cu3(OH(SO4(C3H2ClN23(C3H7NO(H2O]2·4C3H7NO·2H2O. The centrosymmetric dimeric molecule consists of two trinuclear copper–pyrazolate units bridged by two sulfate ions. The title compound provides the first example of a trinuclear copper–pyrazolate complex with three different terminal ligands on the Cu atoms, and also the first example of such complex with a strongly binding basal sulfate ion. Within each trinuclear unit, the CuII atoms are bridged by μ-pyrazolate groups and a central μ3-OH group, and are coordinated by terminal sulfate, H2O and DMF ligands, respectively. Moreover, the sulfate O atoms coordinate at the apical position to the Cu atoms of the symmetry-related unit, providing square–pyramidal coordination geometry around each copper cation. The metal complex and solvent molecules are involved in O—H...O hydrogen bonds, leading to a two-dimensional network parallel to (10-1.

  12. Sulfate-bridged dimeric trinuclear copper(II)-pyrazolate complex with three different terminal ligands.

    Science.gov (United States)

    Mezei, Gellert

    2016-08-01

    The reaction of CuSO4·5H2O, 4-chloro-pyrazole (4-Cl-pzH) and tri-ethyl-amine (Et3N) in di-methyl-formamide (DMF) produced crystals of di-aqua-hexa-kis-(μ-4-chloro-pyrazolato-κ(2) N:N')bis-(N,N-di-methyl-formamide)di-μ3-hydroxido-bis-(μ4-sulfato-κ(4) O:O':O'':O'')hexa-copper(II) N,N-di-methyl-formamide tetra-solvate dihydrate, [Cu3(OH)(SO4)(C3H2ClN2)3(C3H7NO)(H2O)]2·4C3H7NO·2H2O. The centrosymmetric dimeric molecule consists of two trinuclear copper-pyrazolate units bridged by two sulfate ions. The title compound provides the first example of a trinuclear copper-pyrazolate complex with three different terminal ligands on the Cu atoms, and also the first example of such complex with a strongly binding basal sulfate ion. Within each trinuclear unit, the Cu(II) atoms are bridged by μ-pyrazolate groups and a central μ3-OH group, and are coordinated by terminal sulfate, H2O and DMF ligands, respectively. Moreover, the sulfate O atoms coordinate at the apical position to the Cu atoms of the symmetry-related unit, providing square-pyramidal coordination geometry around each copper cation. The metal complex and solvent mol-ecules are involved in O-H⋯O hydrogen bonds, leading to a two-dimensional network parallel to (10-1).

  13. Chelate effects in sulfate binding by amide/urea-based ligands.

    Science.gov (United States)

    Jia, Chuandong; Wang, Qi-Qiang; Begum, Rowshan Ara; Day, Victor W; Bowman-James, Kristin

    2015-07-01

    The influence of chelate and mini-chelate effects on sulfate binding was explored for six amide-, amide/amine-, urea-, and urea/amine-based ligands. Two of the urea-based hosts were selective for SO4(2-) in water-mixed DMSO-d6 systems. Results indicated that the mini-chelate effect provided by a single urea group with two NH binding sites appears to provide enhanced binding over two amide groups. Furthermore, additional urea binding sites incorporated into the host framework appeared to overcome to some extent competing hydration effects with increasing water content.

  14. Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel 'cubane' and 'step' tetramer forms of AgSCN : PR3 (1:1)4.

    Science.gov (United States)

    Bowmaker, Graham A; Di Nicola, Corrado; Effendy; Hanna, John V; Healy, Peter C; King, Scott P; Marchetti, Fabio; Pettinari, Claudio; Robinson, Ward T; Skelton, Brian W; Sobolev, Alexandre N; Tăbăcaru, Aurel; White, Allan H

    2013-01-07

    Adducts of a number of tertiary pnicogen ligands ER(3) (triphenyl-phosphine and -arsine (PPh(3),AsPh(3)), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl)phosphine (P(C(6)H(4)-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl)phosphine (PCy(3))), with silver(I) thiocyanate, AgSCN are structurally and spectroscopically characterized. The 1:3 AgSCN : ER(3) complexes structurally defined (for PPh(3),AsPh(3) (diversely solvated)) take the form [(R(3)E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph(3)E)Ag(NCS)]. A 1:2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag()Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1:1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy(3); binuclear forms [(R(3)P)Ag()Ag(PR(3))] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy(3); these latter may be considered as extensions of the 'cubane' and 'step' forms previously described for [(R(3)E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the ν(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh(3) with PPh(2)py apparently causes a significant decrease in ν(CN) to well below the range expected for bridging SCN in these structures. (31)P CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra.

  15. Mechanism for the formation of substituted manganese(V) cyanidonitrido complexes: crystallographic and kinetic study of the substitution reactions of trans-[MnN(H2O)(CN)4]2- with monodentate pyridine and bidentate pyridine-carboxylate ligands.

    Science.gov (United States)

    van der Westhuizen, Hendrik J; Meijboom, Reinout; Schutte, Marietjie; Roodt, Andreas

    2010-10-18

    Dissolution of [(CH(3))N](2)Na[MnN(CN)(5)]·H(2)O in water results in the rapid dissociation of the trans-CN(-) ligand to form trans-[MnN(H(2)O)(CN)(4)](2-)(aq), which reacts with monodentate pyridine ligands such as 3-methyl and 4-methyl pyridine to form the corresponding mono-substituted complexes, of which the molecular structures obtained from X-ray crystallography, trans-[MnN(3-pic)(CN)(4)](2-) and trans-[MnN(4-pic)(CN)(4)](2-), are reported. [MnN(H(2)O)(CN)(4)](2-)(aq) also reacts with bidentate nucleophiles such as pyridine-2-carboxylate (pico) and quinoline-2-carboxylate (quino), yielding the corresponding [MnN(η(2)-pico)(CN)(3)](2-) and [MnN(η(2)-quino)(CN)(3)](2-) complexes as determined by X-ray crystallography. The formation kinetics of pyridine-2-carboxylate and three different pyridine-2,x-dicarboxylate ligands (x = 3, 4, 5) are reported, and two consecutive reaction steps are proposed, defined as the formation of the [MnN(η(1)-pico)(CN)(4)](3-) and [MnN(η(2)-pico)(CN)(3)](3-) complexes, respectively. Only the second steps could be spectrophotometrically observed and kinetically investigated. The first reaction is attributed to the rapid aqua substitution of [MnN(H(2)O)(CN)(4)](2-), thermodynamically unfavored and too fast to observe by conventional rapid third generation stopped-flow techniques. The second, slower reaction is attributed to cyanido substitution, with overall formation rate constants (25 °C; k(1)'; M(-1) s(-1)) and corresponding activation parameters (ΔH(k1')(double dagger), kJ mol(-1), ΔS(k1')(double dagger), J K(-1) mol(-1)) for the following entering bidentate nucleophiles: pyridine-2-carboxylate: (1.15 ± 0.04) × 10(-3), 102 ± 1, and 48 ± 3; pyridine-2,3-dicarboxylate: (1.1 ± 0.1) × 10(-3), 93 ± 2, and 20 ± 4; pyridine-2,4-dicarboxylate (8.5 ± 0.5) × 10(-4), 123 ± 5, and 115 ± 14; pyridine-2,5-dicarboxylate: (1.08 ± 0.04) × 10(-3), 106 ± 1, and 60 ± 2. A dissociative activation for the cyanido substitution

  16. Structural and biochemical characterization of ligand recognition by CysB, the master regulator of sulfate metabolism.

    Science.gov (United States)

    Mittal, Monica; Singh, Appu Kumar; Kumaran, S

    2017-08-21

    CysB, a member of LysR-type transcriptional regulators, up-regulates the expression of genes associated with sulfate metabolism and cysteine biosynthesis. CysB is activated under sulfur limiting conditions by O-acetylserine (OAS) and N-acetylserine (NAS), but the activation mechanism of CysB remain unknown. Here, we report four crystal structures of ligand binding domains of CysB (CysB-LBD) in apo form and in complex with sulfate, OAS, and NAS. Our results show that CysB has two distinct allosteric ligand binding sites; a sulfate and NAS specific site-1 and a second, NAS and OAS specific site-2. All three ligands bind through the induced-fit mechanism. Surprisingly, OAS remodels the site-1 by binding to site-2, suggesting that site-1 and site-2 are coupled allosterically. Using DNA binding and site-directed mutagenesis approach, we show that OAS enhances NAS mediated activation and mutation at site-1 has no effect on site-2 mediated OAS activation. Results indicate that inducer binding triggered signals from OAS-Specific site-2 are relayed to DBD through site-1. Together, results presented here suggest that induced-fit binding and allosteric coupling between two ligand binding sites and DBD underlie the key feature of CysB activation. Further, this study provides first structural glimpse into recognition of inducer ligands by CysB and provides a general framework to understand how LTTR family regulators respond to dual activators. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  17. Significance of Ligand Exchange Relating to Sulfate in Retarding Acidification of Variable Charge Soils Caused by Acid Rain

    Institute of Scientific and Technical Information of China (English)

    WANGJINGHUA; YUTIANREN

    1996-01-01

    For the purpose of evaluating the role of ligand exchange of sulfate ions in retarding the rate of acidification of variable charge soils,the changes in pH after the addition of different amounts of HNO3 or H2SO4 to representative soils of China were measured .A difference between pH changes caused by the two kinds of acids was observed only for variable charge soils and kaolinite,but not for constant charge soils and bentonite,The larger the proportion of H2SO4 in the HNO3-H2SO4 mixture,the lower the calculated H+ ion activities remained in the suspension.The difference in H+ ion activities between H2SO4 systems and HNO3 systems was larger for soils with a low base-saturation(BS) percentage than those with a high BS percentage.The removal of free iron oxides from the soil led to a decrease in the difference,while the coating of Fe2O3 on a bentonite resulted in a remarkable appearance of the difference.The effect of ligand exchange on the acidity status of the soil varied with the soil type.Surface soils with a high organic matter content showed a less pronounced effect of ligand exchange than subsoils did.It was estimated that when acid rain chiefly containing H2SO4 was deposited on variable charge soils the acidification rate might be slower by 20%-40% than that when the acid rain chiefly contained HNO3 for soils with a high organic matter content,and that the rate might be half of that caused by HNO3 for soils with a low organic matter content,especially for latosols.

  18. Tetracarboxylatoplatinum(IV) complexes featuring monodentate leaving groups - A rational approach toward exploiting the platinum(IV) prodrug strategy.

    Science.gov (United States)

    Höfer, Doris; Varbanov, Hristo P; Legin, Anton; Jakupec, Michael A; Roller, Alexander; Galanski, Markus; Keppler, Bernhard K

    2015-12-01

    A series of novel symmetrically and unsymmetrically coordinated platinum(IV) complexes with monodentate carboxylato ligands was synthesized. The compounds exhibit a general coordination sphere of [Pt(en)(OCOR)2(OCOR')(OCOR″)], where the carboxylato ligands are represented by acetato and succinic acid monoester ligands. Dicarboxylatoplatinum(II) complexes were synthesized and oxidized symmetrically or unsymmetrically to obtain platinum(IV) complexes, which were subsequently carboxylated with noncyclic anhydrides. The compounds were investigated in detail by elemental analysis, mass spectrometry, infrared and multinuclear ((1)H, (13)C, (15)N, (195)Pt) NMR spectroscopy as well as by X-ray diffraction in some cases. The reduction behavior was followed by NMR spectroscopy, while stability and lipophilicity were examined by analytical reversed phase HPLC measurements. Cytotoxic properties were studied in three human cancer cell lines derived from cisplatin sensitive ovarian teratocarcinoma (CH1/PA-1), cisplatin insensitive colon carcinoma (SW480) and non-small cell lung cancer (A549). Thereby, the most lipophilic (yet water soluble) platinum(IV) complexes showed promising IC50 values in the low micromolar and even nanomolar range, demonstrating the significant advantage of using equatorially coordinated monodentate carboxylato ligands. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Heparan sulfate acts as a bone morphogenetic protein coreceptor by facilitating ligand-induced receptor hetero-oligomerization.

    Science.gov (United States)

    Kuo, Wan-Jong; Digman, Michelle A; Lander, Arthur D

    2010-11-15

    Cell surface heparan sulfate (HS) not only binds several major classes of growth factors but also sometimes potentiates their activities--an effect usually termed "coreception." A view that coreception is due to the stabilization of growth factor-receptor interactions has emerged primarily from studies of the fibroblast growth factors (FGFs). Recent in vivo studies have strongly suggested that HS also plays an important role in regulating signaling by the bone morphogenetic proteins (BMPs). Here, we provide evidence that the mechanism of coreception for BMPs is markedly different from that established for FGFs. First, we demonstrate a direct, stimulatory role for cell surface HS in the immediate signaling activities of BMP2 and BMP4, and we provide evidence that HS-BMP interactions are required for this effect. Next, using several independent assays of ligand binding and receptor assembly, including coimmunoprecipitation, cross-linking, and fluorescence fluctuation microscopy, we show that HS does not affect BMP binding to type I receptor subunits but instead enhances the subsequent recruitment of type II receptor subunits to BMP-type I receptor complexes. This suggests a view of HS as a catalyst of the formation of signaling complexes, rather than as a stabilizer of growth factor binding.

  20.  Dehydroepiandrosterone sulfate, osteoprotegerin and its soluble ligand sRANKL and bone metabolism in girls with anorexia nervosa

    Directory of Open Access Journals (Sweden)

    Zofia Ostrowska

    2012-09-01

    Full Text Available  Background:Only scarce data exist concerning the relationship between dehydroepiandrosterone (DHEA and/or its sulfate form DHEAS and bone status in adolescents with anorexia nervosa (AN.Aim:We investigated whether a relationship existed between DHEAS and bone metabolism (as assessed based on serum osteocalcin [OC], and collagen type I cross-linked carboxy-terminal telopeptide [CTx]. We also aimed to establish whether the above mentioned relationship might be affected by osteoprotegerin (OPG and its soluble ligand sRANKL.Material/Methods:Fifty-six female patients with AN and 21 healthy female subjects aged 13 to 16 years participated in the study. Serum DHEAS, OC, CTx, OPG and sRANKL were measured by ELISA.Results:Our female patients with AN demonstrated significant suppression of DHEAS and bone markers, an increase in OPG and sRANKL levels, and a reduction of the OPG/sRANKL ratio. DHEAS, CTx and the OPG/sRANKL ratio correlated positively with BMI. A significant positive correlation was also observed between DHEAS and the OPG/sRANKL ratio, OC and the OPG/sRANKL ratio, and CTx and sRANKL. The correlation was negative in the case of DHEAS and CTx, DHEAS and sRANKL, CTx and the OPG/sRANKL ratio, and sRANKL and the OPG/sRANKL ratio.Discussion/DHEAS suppression in girls with anorexia nervosa was associated with a decrease in the levels of bone markers, an increase in OPG and sRANKL concentrations and a significant decrease in the OPG/sRANKL ratio. DHEAS suppression in girls with anorexia nervosa might have a harmful effect on their bone tissue, probably via a shift in the OPG/RANKL ratio toward a functional excess of sRANKL.

  1. Bidentates versus monodentates in asymmetric hydrogenation catalysis: synergic effects on rate and allosteric effects on enantioselectivity.

    Science.gov (United States)

    Norman, David W; Carraz, Charles A; Hyett, David J; Pringle, Paul G; Sweeney, Joseph B; Orpen, A Guy; Phetmung, Hirrahataya; Wingad, Richard L

    2008-05-28

    C 1-Symmetric phosphino/phosphonite ligands are prepared by the reactions of Ph 2P(CH 2) 2P(NMe 2) 2 with ( S)-1,1'-bi-2-naphthol (to give L A ) or ( S)-10,10'-bi-9-phenanthrol (to give L B ). Racemic 10,10'-bi-9-phenanthrol is synthesized in three steps from phenanthrene in 44% overall yield. The complexes [PdCl 2( L A,B )] ( 1a, b), [PtCl 2( L A,B )] ( 2a, b), [Rh(cod)( L A,B )]BF 4 ( 3a, b) and [Rh( L A,B ) 2]BF 4 ( 4a, b) are reported and the crystal structure of 1a has been determined. A (31)P NMR study shows that M, a 1:1 mixture of the monodentates, PMePh 2 and methyl monophosphonite L 1a (based on ( S)-1,1 '-bi-2-naphthol), reacts with 1 equiv of [Rh(cod) 2]BF 4 to give the heteroligand complex [Rh(cod)(PMePh 2)( L 1a )]BF 4 ( 5) and homoligand complexes [Rh(cod)(PMePh 2) 2]BF 4 ( 6) and [Rh(cod)( L 1a ) 2]BF 4 ( 7) in the ratio 2:1:1. The same mixture of 5- 7 is obtained upon mixing the isolated homoligand complexes 6 and 7 although the equilibrium is only established rapidly in the presence of an excess of PMePh 2. The predominant species 5 is a monodentate ligand complex analogue of the chelate 3a. When the mixture of 5- 7 is exposed to 5 atm H 2 for 1 h (the conditions used for catalyst preactivation in the asymmetric hydrogenation studies), the products are identified as the solvento species [Rh(PMePh 2)( L 1a )(S) 2]BF 4 ( 5'), [Rh(S) 2(PMePh 2) 2]BF 4 ( 6') and [Rh(S) 2( L 1a ) 2]BF 4 ( 7') and are formed in the same 2:1:1 ratio. The reaction of M with 0.5 equiv of [Rh(cod) 2]BF 4 gives exclusively the heteroligand complex cis-[Rh(PMePh 2) 2( L 1a ) 2]BF 4 ( 8), an analogue of 4a. The asymmetric hydrogenation of dehydroamino acid derivatives catalyzed by 3a, b is reported, and the enantioselectivities are compared with those obtained with (a) chelate catalysts derived from analogous diphosphonite ligands L 2a and L 2b , (b) catalysts based on methyl monophosphonites L 1a and L 1b , and (c) catalysts derived from mixture M. For the cinnamate and

  2. Structure of a dinuclear cadmium complex with 2,2'-bi-pyridine, monodentate nitrate and 3-carb-oxy-6-methyl-pyridine-2-carboxyl-ate ligands: intra-molecular carbon-yl(lone pair)⋯π(ring) and nitrate(π)⋯π(ring) inter-actions.

    Science.gov (United States)

    Granifo, Juan; Suarez, Sebastián; Baggio, Ricardo

    2015-08-01

    The centrosymmetric dinuclear complex bis-(μ-3-carb-oxy-6-methyl-pyridine-2-carboxyl-ato)-κ(3) N,O (2):O (2);κ(3) O (2):N,O (2)-bis-[(2,2'-bi-pyridine-κ(2) N,N')(nitrato-κO)cadmium] methanol monosolvate, [Cd2(C8H6NO4)2(NO3)2(C10H8N2)2]·CH3OH, was isolated as colourless crystals from the reaction of Cd(NO3)2·4H2O, 6-methyl-pyridine-2,3-di-carb-oxy-lic acid (mepydcH2) and 2,2'-bi-pyridine in methanol. The asymmetric unit consists of a Cd(II) cation bound to a μ-κ(3) N,O (2):O (2)-mepydcH(-) anion, an N,N'-bidentate 2,2'-bi-pyridine group and an O-mono-dentate nitrate anion, and is completed with a methanol solvent mol-ecule at half-occupancy. The Cd complex unit is linked to its centrosymmetric image through a bridging mepydcH(-) carboxyl-ate O atom to complete the dinuclear complex mol-ecule. Despite a significant variation in the coordination angles, indicating a considerable departure from octa-hedral coordination geometry about the Cd(II) atom, the Cd-O and Cd-N distances in this complex are surprisingly similar. The crystal structure consists of O-H⋯O hydrogen-bonded chains parallel to a, further bound by C-H⋯O contacts along b to form planar two-dimensional arrays parallel to (001). The juxtaposed planes form inter-stitial columnar voids that are filled by the methanol solvent mol-ecules. These in turn inter-act with the complex mol-ecules to further stabilize the structure. A search in the literature showed that complexes with the mepydcH(-) ligand are rare and complexes reported previously with this ligand do not adopt the μ-κ(3) coordination mode found in the title compound.

  3. DMBT1 functions as pattern-recognition molecule for poly-sulfated and poly-phosphorylated ligands

    DEFF Research Database (Denmark)

    End, Caroline; Bikker, Floris; Renner, Marcus

    2009-01-01

    Deleted in malignant brain tumors 1 (DMBT1) is a secreted glycoprotein displaying a broad bacterial-binding spectrum. Recent functional and genetic studies linked DMBT1 to the suppression of LPS-induced TLR4-mediated NF-kappaB activation and to the pathogenesis of Crohn's disease. Here, we aimed...... at unraveling the molecular basis of its function in mucosal protection and of its broad pathogen-binding specificity. We report that DMBT1 directly interacts with dextran sulfate sodium (DSS) and carrageenan, a structurally similar sulfated polysaccharide, which is used as a texturizer and thickener in human...... dietary products. However, binding of DMBT1 does not reduce the cytotoxic effects of these agents to intestinal epithelial cells in vitro. DSS and carrageenan compete for DMBT1-mediated bacterial aggregation via interaction with its bacterial-recognition motif. Competition and ELISA studies identify poly...

  4. Catalytic enantioselective addition of organometallic reagents to N-formylimines using monodentate phosphoramidite ligands

    NARCIS (Netherlands)

    Pizzuti, Maria Gabriella; Minnaard, Adriaan J.; Feringa, Ben L.

    2008-01-01

    [GRAPHICS] The asymmetric synthesis of protected amines via the copper/phosphoramidite-catalyzed addition of organozine and organoaluminum reagents to N-acylimines, generated in situ from aromatic and aliphatic alpha-amidosulfones, is reported. High yields of optically active N-formyl-protected amin

  5. Catalytic Enantioselective Addition of Organometallic Reagents to N-Formylimines Using Monodentate Phosphoramidite Ligands

    NARCIS (Netherlands)

    Pizzuti, Maria Gabriella; Minnaard, Adriaan J.; Feringa, Bernard

    2008-01-01

    The asymmetric synthesis of protected amines via the copper/phosphoramidite-catalyzed addition of organozinc and organoaluminum reagents to N-acylimines, generated in situ from aromatic and aliphatic α-amidosulfones, is reported. High yields of optically active N-formyl-protected amines and enantios

  6. Fast Palladium Catalyzed Arylation of Alkenes Using Bulky Monodentate Phosphorus Ligands

    NARCIS (Netherlands)

    Strijdonck, Gino P.F. van; Boele, Maarten D.K.; Kamer, Paul C.J.; Vries, Johannes G. de; Leeuwen, Piet W.N.M. van

    1999-01-01

    Complex 1b shows an unprecedented high activity in the Heck reaction. Kinetic studies show that in this system not the oxidative addition but the alkene coordination/migratory insertion is the rate determining step.

  7. Mg(II)-induced second-harmonic generation based on bis-monodentate coordination mode of thiobarbiturate.

    Science.gov (United States)

    Gong, Yun; Hao, Zhi; Li, JingHua; Wu, Tao; Lin, JianHua

    2013-05-14

    Utilizing a SHG inactive ligand, 2-thiobarbituric acid (H3L), three metal complexes formulated as M(H2L)2(H2O)2·2DMF (M = Mg 1 and Ni 2) and Co(H2L)2(H2O)2 (3) were synthesized and structurally characterized by single-crystal X-ray diffractions. Complexes 1 and 2 exhibit a similar uninodal 3D acentric diamondoid framework. Complex 1 displays SHG response using 1064 nm radiation, whereas complex 2 is SHG inactive under the same condition. Complex 3 is also SHG inactive, which exhibits a centro-symmetrical chain-like structure built from Co(II) ions and double strands of H2L(-)-bridge with the inversion center occupied by the metal(II) ion. In the three complexes, the negative charge of H2L(-) ligand is delocalized over the O=C-CH-C=O group and H2L(-) can be considered as a β-diketo derivative. H2L(-) shows a bis-monodentate coordination fashion and acts as a u2-bridge in the three complexes, which is different from the classical chelating fashion of β-diketo ligand. In complexes 1 and 2, the two β-diketo oxygen atoms of H2L(-) are coordinated to two metal centers. Whereas in complex 3, H2L(-) ligand links two Co(II) centers via one oxygen and one sulphur atoms. The three complexes exhibit different UV-vis absorption, photoluminescence properties and thermal stabilities.

  8. Bis(ortho)-Chelated Bis(phosphanyl)aryl Ruthenium(II).Complexes Containing an h1 -P-Monodentate or m -BridgingP,h1-P' Bonded R—PCHP Arene Ligand, 1-R-3,5(CH2PPh2)2C2H2 [R= H, Br, or, Si(n-CH2CH2C2F17)3]—Cyclometalation Reaction Intermediates and Potential Catalysts for Use in Fluorinated Biphasic Systems

    NARCIS (Netherlands)

    Koten, G. van; Dani, P.; Richter, B.; Klink, G.P.M. van

    2001-01-01

    Mono- and binuclear ruthenium(II) complexes containing ligands derived from the meta-bis(phosphanyl)arene ligand 1-R-3,5-(CH2PPh2)2C6H3 [R-PCHP: R = H (5), Br (3), or Si(n-CH2CH2C8F17)3 (4)] have been synthesized and fully characterized. On reaction of equimolar amounts of the ruthenium starting mat

  9. Construction of metal-organic frameworks through coordination and hydrogen bonding interactions: Syntheses, structures and photoluminescent properties of metal complexes with macrocyclic ligand

    Science.gov (United States)

    Ouyang, Xing-Mei; Li, Zhen-Wu; Okamura, Taka-aki; Li, Yi-Zhi; Sun, Wei-Yin; Tang, Wen-Xia; Ueyama, Norikazu

    2004-01-01

    A macrocyclic ligand L with two diethylenetriamine units linked by two rigid biphenylene spacers was used as building block for construction of metal-organic frameworks. A silver(I) complex with macrocyclic and open-chain mix-type ligands [Ag 2( L)( L')](ClO 4) 2 ( 1) [ L'=1,6-bis(4-imidazol-1'-ylmethylphenyl)-2,5-diazahexane] was obtained by reaction of L and L' together with AgClO 4·H 2O. It is interesting that the open-chain tetradentate ligand L' only served as a bidentate ligand to bridge the Ag 2L units into an infinite one-dimensional (1D) cationic chain. Neutral 1D chain coordination polymer [Cu 2( L)( μ-SO 4) 2]·3H 2O·3MeOH ( 2) is formed by sulfate bridges between the neighboring Cu 2L units. When L reacted with nickel(II) sulfate instead of copper(II) sulfate, a monomacrocycle molecular complex [Ni 2( L)(H 2O) 4(SO 4) 2] ( 3) was obtained in which the sulfate anion acts as monodentate ligands rather than as bridges. When Cd(II) salts were used for the reactions with L, another two neutral 1D coordination polymers, [Cd 2( L)( μ-Cl) 2Cl 2]·2H 2O ( 4) and [Cd 2( L)( μ-Br) 2Br 2] ( 5), with the same structure were isolated. All the synthesized complexes exhibit three-dimensional framework structures linked by various hydrogen bonds. The photoluminescent properties of the synthesized complexes were studied in the solid state at room temperature, and the Ag(I) and Cd(II) complexes were found to show strong blue luminescence.

  10. Cyclopentadienyl Rhenium (Technetium) Tricarbonyl Complexes Integrated in Estrogen Receptor Ligands for ER+ Tumor Imaging

    Science.gov (United States)

    2006-10-01

    Oxidation to the N-oxide 38 with peroxy acid, with subsequent rearrangement provides the alcohol 39. Treatment of 39 with triflic anhydride in...anionic monodentate ligand is bromide for the pyridyl-imine rhenium tricarbonyl bromide (PIRB VI) system. A nomenclature of PIRB ligands is based

  11. Solid-Phase Parallel Synthesis of Phosphite Ligands

    NARCIS (Netherlands)

    Swennenhuis, Bert H.G.; Chen, Ruifang; Leeuwen, Piet W.N.M. van; Vries, Johannes G. de; Kamer, Paul C.J.

    2008-01-01

    Various routes for the synthesis of polymer-bound phosphites and phosphoramidites have been investigated. In the presence of a suitable activator the supported phosphoramidites react cleanly with alcohols to give the corresponding monodentate phosphite ligands in solution. We have applied this novel

  12. Syndecan heparan sulfate proteoglycans

    DEFF Research Database (Denmark)

    Gomes, Angélica Maciel; Sinkeviciute, Dovile; Multhaupt, Hinke A.B.

    2016-01-01

    Virtually all animal cells express heparan sulfate proteoglycans on the cell surface and in the extracellular matrix. Syndecans are a major group of transmembrane proteoglycans functioning as receptors that mediate signal transmission from the extracellular microenvironment to the cell. Their hep......Virtually all animal cells express heparan sulfate proteoglycans on the cell surface and in the extracellular matrix. Syndecans are a major group of transmembrane proteoglycans functioning as receptors that mediate signal transmission from the extracellular microenvironment to the cell....... Their heparan sulfate chains, due to their vast structural diversity, interact with a wide array of ligands including potent regulators of adhesion, migration, growth and survival. Frequently, ligands interact with cell surface heparan sulfate in conjunction with high affinity receptors. The consequent...... signaling can therefore be complex, but it is now known that syndecans are capable of independent signaling. This review is divided in two sections, and will first discuss how the assembly of heparan sulfate, the anabolic process, encodes information related to ligand binding and signaling. Second, we...

  13. A one-dimensional copper(II) coordination polymer incorporating succinate and N,N-diethylethylenediamine ligands: crystallographic analysis, vibrational and surface features, and DFT analysis.

    Science.gov (United States)

    Şen, Fatih; Kansiz, Sevgi; Uçar, İbrahim

    2017-07-01

    Transition metal atoms can be bridged by aliphatic dicarboxylate ligands to produce chains, layers and frameworks. The reaction of copper sulfate with succinic acid (H2succ) and N,N-diethylethylenediamine (deed) in basic solution produces the complex catena-poly[[[(N,N-diethylethylenediamine-κ(2)N,N')copper(II)]-μ-succinato-κ(2)O(1):O(4)] tetrahydrate], {[Cu(C4H4O4)(C6H16N2)]·4H2O}n or {[Cu(succ)(deed)]·4H2O}n. Each carboxylate group of the succinate ligand coordinates to a Cu(II) atom in a monodentate fashion, giving rise to a square-planar coordination environment. The succinate ligands bridge the Cu(II) centres to form one-dimensional polymeric chains. Hydrogen bonds between the ligands and water molecules link these chains into sheets that lie in the ab plane. Density functional theory (DFT) calculations were used to support the experimental data. From these calculations, a good linear correlation was observed between the experimental and theoretically predicted structural and spectroscopic parameters (R(2) ∼ 0.97).

  14. Roles of heparan sulfate sulfation in dentinogenesis.

    Science.gov (United States)

    Hayano, Satoru; Kurosaka, Hiroshi; Yanagita, Takeshi; Kalus, Ina; Milz, Fabian; Ishihara, Yoshihito; Islam, Md Nurul; Kawanabe, Noriaki; Saito, Masahiro; Kamioka, Hiroshi; Adachi, Taiji; Dierks, Thomas; Yamashiro, Takashi

    2012-04-06

    Cell surface heparan sulfate (HS) is an essential regulator of cell signaling and development. HS traps signaling molecules, like Wnt in the glycosaminoglycan side chains of HS proteoglycans (HSPGs), and regulates their functions. Endosulfatases Sulf1 and Sulf2 are secreted at the cell surface to selectively remove 6-O-sulfate groups from HSPGs, thereby modifying the affinity of cell surface HSPGs for its ligands. This study provides molecular evidence for the functional roles of HSPG sulfation and desulfation in dentinogenesis. We show that odontogenic cells are highly sulfated on the cell surface and become desulfated during their differentiation to odontoblasts, which produce tooth dentin. Sulf1/Sulf2 double null mutant mice exhibit a thin dentin matrix and short roots combined with reduced expression of dentin sialophosphoprotein (Dspp) mRNA, encoding a dentin-specific extracellular matrix precursor protein, whereas single Sulf mutants do not show such defective phenotypes. In odontoblast cell lines, Dspp mRNA expression is potentiated by the activation of the Wnt canonical signaling pathway. In addition, pharmacological interference with HS sulfation promotes Dspp mRNA expression through activation of Wnt signaling. On the contrary, the silencing of Sulf suppresses the Wnt signaling pathway and subsequently Dspp mRNA expression. We also show that Wnt10a protein binds to cell surface HSPGs in odontoblasts, and interference with HS sulfation decreases the binding affinity of Wnt10a for HSPGs, which facilitates the binding of Wnt10a to its receptor and potentiates the Wnt signaling pathway, thereby up-regulating Dspp mRNA expression. These results demonstrate that Sulf-mediated desulfation of cellular HSPGs is an important modification that is critical for the activation of the Wnt signaling in odontoblasts and for production of the dentin matrix.

  15. Influence of Axial and Peripheral Ligands on the Electronic Structure of Titanium Phthalocyanines

    NARCIS (Netherlands)

    Pickup, David F.; Zegkinoglou, Ioannis; Ballesteros, Beatriz; Ganivet, Carolina R.; Garcia-Lastra, J. M.; Cook, Peter L.; Johnson, Phillip S.; Rogero, Celia; de Groot, Frank; Rubio, Angel; de la Torre, Gema; Enrique Ortega, J.; Himpsel, F. J.

    2013-01-01

    To discover how molecular changes affect the electronic structure of dye molecules for solar cells, we have investigated four titanium phthalocyanines customized by axial and peripheral ligands (monodentate oxo versus bidentate catechol and tert-butyl versus tert-butylphenoxy, respectively). X-ray a

  16. Ligand-guided pathway selection in nickel-catalyzed couplings of enals and alkynes.

    Science.gov (United States)

    Li, Wei; Montgomery, John

    2012-01-28

    Nickel-catalyzed couplings of enals and alkynes utilizing triethylborane as the reducing agent illustrate a significant dependence on ligand structure. Simple variation of monodentate phosphines allows selective access to alkylative couplings or reductive cycloadditions, while further variation of reaction conditions provides clean access to reductive couplings and redox-neutral couplings.

  17. Influence of axial and peripheral ligands on the electronic structure of titanium phthalocyanines

    DEFF Research Database (Denmark)

    Pickup, David F.; García Lastra, Juan Maria; Rogero, Celia

    2013-01-01

    To discover how molecular changes affect the electronic structure of dye molecules for solar cells, we have investigated four titanium phthalocyanines customized by axial and peripheral ligands (monodentate oxo versus bidentate catechol and tert-butyl versus tert-butylphenoxy, respectively). X-ra...

  18. Tuning of gate adsorption: modification of a flexible metal-organic framework by secondary organic ligands.

    Science.gov (United States)

    Kondo, Atsushi; Fujii, Takuro; Maeda, Kazuyuki

    2014-06-14

    For realizing selective adsorption of targeted molecules, a flexible metal-organic framework (MOF) was modified with monodentate secondary ligands. Although the modified MOF retains CO2 adsorptivities with a vertical adsorption uptake, the material also shows gate adsorptivities of a specific gas molecule that the pristine MOF does not adsorb.

  19. Anion-induced structural transformation of a sulfate-incorporated 2D Cd(II)–organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Li-Wei [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China); Institute of Materials Science and Engineering, National Central University, Taoyuan 320, Taiwan (China); Luo, Tzuoo-Tsair [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China); Wang, Chih-Min [Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 202, Taiwan (China); Lee, Gene-Hsiang; Peng, Shie-Ming [Department of Chemistry, National Taiwan University, Taipei 107, Taiwan (China); Liu, Yen-Hsiang [Department of Chemistry, Fu Jen Catholic University, New Taipei City 242, Taiwan (China); Lee, Sheng-Long [Institute of Materials Science and Engineering, National Central University, Taoyuan 320, Taiwan (China); Lu, Kuang-Lieh [Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan (China)

    2016-07-15

    A Cd(II)–organic framework {[Cd_2(tpim)_4(SO_4)(H_2O)_2]·(SO_4)·21H_2O}{sub n} (1) was synthesized by reacting CdSO{sub 4}·8/3H{sub 2}O and 2,4,5-tri(4-pyridyl)imidazole (tpim) under hydrothermal conditions. A structural analysis showed that compound 1 adopts a layered structure in which the [Cd(tpim){sub 2}]{sub n} chains are linked by sulfate anions. These 2D layers are further packed into a 3D supramolecular framework via π–π interactions. The structure contains two types of SO{sub 4}{sup 2−} anions, i.e., bridging SO{sub 4}{sup 2−} and free SO{sub 4}{sup 2−} anions, the latter of which are included in the large channels of the framework. Compound 1 exhibits interesting anion exchange behavior. In the presence of SCN{sup −} anions, both the bridging and free SO{sub 4}{sup 2−} anions in 1 were completely exchanged by SCN{sup −} ligands to form a 1D species [Cd(tpim){sub 2}(SCN){sub 2}] (1A), in which the SCN{sup –} moieties function as a monodentate ligand. On the other hand, when compound 1 was ion exchanged with N{sub 3}{sup −} anions in aqueous solution, the bridging SO{sub 4}{sup 2−} moieties remained intact, and only the free guest SO{sub 4}{sup 2−} were replaced by N{sub 3}{sup −} anions. The gas adsorption behavior of the activated compound 1 was also investigated. - Highlights: • An interesting anion-induced structural transformation of a sulfate-incorporated 2D Cd(II)–organic framework is reported. • The sulfate-incorporated 2D layer compound exhibits very different anion exchange behavior with respect to SCN{sup −} and N{sub 3}{sup −}. • Both the bridging and free SO{sub 4}{sup 2−} anions in the 2D structure were completely exchanged by SCN{sup −} ligands, resulting in the formation of a 1D species. However, in the case of N{sub 3}{sup −} anions, only the free guest SO{sub 4}{sup 2−} in the structure was replaced.

  20. Atmospheric Hydrogenation of Esters Catalyzed by PNP-Ruthenium Complexes with an N-Heterocyclic Carbene Ligand.

    Science.gov (United States)

    Ogata, Osamu; Nakayama, Yuji; Nara, Hideki; Fujiwhara, Mitsuhiko; Kayaki, Yoshihito

    2016-08-01

    New pincer ruthenium complexes bearing a monodentate N-heterocyclic carbene ligand were synthesized and demonstrated as powerful hydrogenation catalysts. With an atmospheric pressure of hydrogen gas, aromatic, heteroaromatic, and aliphatic esters as well as lactones were converted into the corresponding alcohols at 50 °C. This reaction protocol offers reliable access to alcohols using an easy operational setup.

  1. Study of the spectroscopic characteristics of methyl (ligand) cobaloximes and their antibacterial activity

    Indian Academy of Sciences (India)

    N Navaneetha; P A Nagarjun; S Satyanarayana

    2007-01-01

    Spectroscopic characterization (IR, NMR and electronic spectra) of methyl (ligand) cobaloxime was done, where ligand = pyrazole, dimethyl pyrazole, alanine and alanine methyl ester. The frequency changes in the IR spectra and shifts in the NMR were explained on the basis of basicity of the ligand, steric hindrance, HSAB principle and - back-bonding from metal to ligand. Alanine and alanine methyl ester form more stable complexes than pyrazole and dimethyl pyrazole. Based on their IR and 1H NMR spectra it is inferred that pyrazole and dimethylpyrazole bind to Co (III) via N-2 ring nitrogen, i.e. monodentate coordination.

  2. Investigating silver coordination to mixed chalcogen ligands.

    Science.gov (United States)

    Knight, Fergus R; Randall, Rebecca A M; Wakefield, Lucy; Slawin, Alexandra M Z; Woollins, J Derek

    2012-11-08

    Six silver(I) coordination complexes have been prepared and structurally characterised. Mixed chalcogen-donor acenaphthene ligands L1-L3 [Acenap(EPh)(E'Ph)] (Acenap = acenaphthene-5,6-diyl; E/E' = S, Se, Te) were independently treated with silver(I) salts (AgBF₄/AgOTf). In order to keep the number of variables to a minimum, all reactions were carried out using a 1:1 ratio of Ag/L and run in dichloromethane. The nature of the donor atoms, the coordinating ability of the respective counter-anion and the type of solvent used in recrystallisation, all affect the structural architecture of the final silver(I) complex, generating monomeric, silver(I) complexes {[AgBF₄(L)₂] (1 L = L1; 2 L = L2; 3 L = L3), [AgOTf(L)₃] (4 L = L1; 5 L = L3), [AgBF₄(L)₃] (2a L = L1; 3a L = L3)} and a 1D polymeric chain {[AgOTf(L3)](n) 6}. The organic acenaphthene ligands L1-L3 adopt a number of ligation modes (bis-monodentate μ₂-η²-bridging, quasi-chelating combining monodentate and η⁶-E(phenyl)-Ag(I) and classical monodentate coordination) with the central silver atom at the centre of a tetrahedral or trigonal planar coordination geometry in each case. The importance of weak interactions in the formation of metal-organic structures is also highlighted by the number of short non-covalent contacts present within each complex.

  3. Investigating Silver Coordination to Mixed Chalcogen Ligands

    Directory of Open Access Journals (Sweden)

    J. Derek Woollins

    2012-11-01

    Full Text Available Six silver(I coordination complexes have been prepared and structurally characterised. Mixed chalcogen-donor acenaphthene ligands L1–L3 [Acenap(EPh(E'Ph] (Acenap = acenaphthene-5,6-diyl; E/E' = S, Se, Te were independently treated with silver(I salts (AgBF4/AgOTf. In order to keep the number of variables to a minimum, all reactions were carried out using a 1:1 ratio of Ag/L and run in dichloromethane. The nature of the donor atoms, the coordinating ability of the respective counter-anion and the type of solvent used in recrystallisation, all affect the structural architecture of the final silver(I complex, generating monomeric, silver(I complexes {[AgBF4(L2] (1 L = L1; 2 L = L2; 3 L = L3, [AgOTf(L3] (4 L = L1; 5 L = L3, [AgBF4(L3] (2a L = L1; 3a L = L3} and a 1D polymeric chain {[AgOTf(L3]n 6}. The organic acenaphthene ligands L1-L3 adopt a number of ligation modes (bis-monodentate μ2-η2-bridging, quasi-chelating combining monodentate and η6-E(phenyl-Ag(I and classical monodentate coordination with the central silver atom at the centre of a tetrahedral or trigonal planar coordination geometry in each case. The importance of weak interactions in the formation of metal-organic structures is also highlighted by the number of short non-covalent contacts present within each complex.

  4. Copper-Catalyzed Enantioselective Synthesis of α-Hydroxyamine Using Monodentate Phosphoramidites

    Institute of Scientific and Technical Information of China (English)

    DONG,Lin; CUN,Lin-Feng; GONG,Liu-Zhu; MI,Ai-Qiao; JIANG,Yao-Zhong

    2004-01-01

    @@ Development of new methods for the introduction of a nitrogen atom to a carbonyl group is still the most important synthetic target. Cu-catalyzed addition of organozinc reagents to α,β-unsaturated carbonyl compounds has been the subject of intensive investigation.[1] Moreover, trapping of the intermediate Zn-enolates has been achieved using nitrosobenzene. To demonstrate the feasibility of developing enantioselective variants of these tandem C-C bond formations,α,β-unsaturated substrates a~d was subjected to standard reaction conditions using Feringa's (L1*, L2*) and our own phosphoramidite ligands (L3*, L4*). In this reaction, medium to high levels of enantioselectivities were observed.

  5. Synthesis and transition metal coordination chemistry of a novel hexadentate bispidine ligand.

    Science.gov (United States)

    Comba, Peter; Rudolf, Henning; Wadepohl, Hubert

    2015-02-14

    Reported is the new bispidine-derived hexadentate ligand (L = 3-(2-methylpyridyl)-7-(bis-2-methylpyridyl)-3,7-diazabicyclo[3.3.1]nonane) with two tertiary amine and four pyridine donor groups. This ligand can form heterodinuclear and mononuclear complexes and, in the mononuclear compounds discussed here, the ligand may coordinate as a pentadentate ligand, with one of the bispyridinemethane-based pyridine groups un- or semi-coordinated, or as a hexadentate ligand, leading to a pentagonal pyramidal coordination geometry or, with an additional monodentate ligand, to a heptacoordinate pentagonal bipyramidal structure. The solution and solid state data presented here indicate that, with the relatively small Cu(II) and high-spin Fe(II) ions the fourth pyridine group is only semi-coordinated for steric reasons and, with the larger high-spin Mn(II) ion genuine heptacoordination is observed but with a relatively large distortion in the pentagonal equatorial plane.

  6. Sulfate inhibition effect on sulfate reducing bacteria

    Directory of Open Access Journals (Sweden)

    Sulaiman Al Zuhair

    2008-12-01

    Full Text Available There is an increasing interest in the potential of bacterial sulfate reduction as an alternative method for sulfate removal from wastewater. Under anaerobic conditions, sulfate-reducing bacteria (SRB utilize sulfate to oxidize organic compounds and generate sulfide (S2-. SRB were successfully isolated from sludge samples obtained from a local petroleum refinery, and used for sulfate removal. The effects of initial sulfate concentration, temperature and pH on the rate of bacterial growth and anaerobic sulfate removal were investigated and the optimum conditions were identified. The experimental data were used to determine the parameters of two proposed kinetic model, which take into consideration substrate inhibition effect. Keywords: Sulfate Reducing Bacteria, Sulfate, Kinetic Model, Biotreatement, Inhibition Received: 31 August 2008 / Received in revised form: 18 September 2008, Accepted: 18 September 2008 Published online: 28 September 2008

  7. Synthesis and structural studies of half-sandwich Cp* rhodium and Cp* iridium complexes featuring mono, bi and tetradentate nitrogen and oxygen donor ligands

    Indian Academy of Sciences (India)

    NARASINGA RAO PALEPU; WERNER KAMINSKY; MOHAN RAO KOLLIPARA

    2017-05-01

    A series of Cp*Rh and Cp*Ir complexes of various nitrogen and oxygen donor ligands were synthesized and characterized. Mono, bi and tetradentate ligands were used to synthesize mononuclear and dinuclear complexes. Schiff base derivatives of picolinic hydrazine and 5-aminoquinoline were used in thesynthesis of complexes 1–8. Among the ligands used for complexation, L1 and L2 act as bidentate, L3 as monodentate and L4 as tetradentate in forming the corresponding complexes. All the complexes were characterized by spectroscopic techniques and the structures of complexes 2, 3, 5 and 7 were unambiguouslycharacterized by single crystal X-ray crystallography. Complexes 2 and 7 were found to have π-π stacking interactions and solvent to complex interactions, respectively. Metal-mediated deprotonation of N-H and monodentate binding of nitrogen are attributed to the formation of neutral complexes whereas ionic complexes are formed by (N,O) bonding.

  8. Preparation, characterization, and antitumor activity of new ethylenediamine platinum(IV) complexes containing mixed carboxylate ligands.

    Science.gov (United States)

    Khokhar, A R; Deng, Y; Kido, Y; Siddik, Z H

    1993-05-01

    A series of ethylenediamine platinum(IV) complexes of the type PtIV(en)XA2 and PtIV(en)X'2A2, where X = 1,1-cyclobutanedicarboxylato or malonato, X' = chloro, cyclobutanecarboxylato, cyclopentanecarboxylato, or cyclohexanecarboxylato, and A = acetato or trifluoroacetato were synthesized and characterized by elemental analysis, infrared, and NMR (13C and 195Pt) spectroscopic techniques. These compounds had good to excellent antitumor activity against murine leukemia L1210 cells. Complexes with axial trifluoroacetate groups were superior to those with acetate ligands. Those possessing both axial trifluoroacetate groups and monodentate bis-carboxylate ligands in the equatorial positions were the most active in the series investigated.

  9. Cationic Gold Clusters Ligated with Differently Substituted Phosphines: Effect of Substitution on Ligand Reactivity and Binding

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Olivares, Astrid M.; Hill, David E.; Laskin, Julia

    2015-01-01

    We present a systematic study of the effect of the number of methyl (Me) and cyclohexyl (Cy) functional groups in monodentate phosphine ligands on the solution-phase synthesis of ligated sub-nanometer gold clusters and their gas-phase fragmentation pathways. Small mixed ligand cationic gold clusters were synthesized using ligand exchange reactions between pre-formed triphenylphosphine ligated (PPh3) gold clusters and monodentate Me- and Cy-substituted ligands in solution and characterized using electrospray ionization mass spectrometry (ESI-MS) and collision-induced dissociation (CID) experiments. Under the same experimental conditions, larger gold-PPh3 clusters undergo efficient exchange of unsubstituted PPh3 ligands for singly Me- and Cy-substituted PPh2Me and PPh2Cy ligands. The efficiency of ligand exchange decreases with an increasing number of Me or Cy groups in the substituted phosphine ligands. CID experiments performed for a series of ligand-exchanged gold clusters indicate that loss of a neutral Me-substituted ligand is preferred over loss of a neutral PPh¬3 ligand while the opposite trend is observed for Cy-substituted ligands. The branching ratio of the competing ligand loss channels is strongly correlated with the electron donating ability of the phosphorous lone pair as determined by the relative proton affinity of the ligand. The results indicate that the relative ligand binding energies increase in the order PMe3 < PPhMe2 < PPh2Me < PPh3< PPh2Cy < PPhCy2< PCy3. Furthermore, the difference in relative ligand binding energies increases with the number of substituted PPh3-mMem or PPh3-mCym ligands (L) exchanged onto each cluster. This study provides the first experimental determination of the relative binding energies of ligated gold clusters containing differently substituted monophosphine ligands, which are important to controlling their synthesis and reactivity in solution. The results also indicate that ligand substitution is an important

  10. Curcumin as the OO bidentate ligand in "2 + 1" complexes with the [M(CO)3]+ (M = Re, 99mTc) tricarbonyl core for radiodiagnostic applications.

    Science.gov (United States)

    Sagnou, Marina; Benaki, Dimitra; Triantis, Charalampos; Tsotakos, Theodoros; Psycharis, Vassilis; Raptopoulou, Catherine P; Pirmettis, Ioannis; Papadopoulos, Minas; Pelecanou, Maria

    2011-02-21

    The synthesis and characterization of "2 + 1" complexes of the [M(CO)(3)](+) (M = Re, (99m)Tc) core with the β-diketones acetylacetone (complexes 2, 8) and curcumin (complexes 5, 10 and 6, 11) as bidentate OO ligands, and imidazole or isocyanocyclohexane as monodentate ligands is reported. The complexes were synthesized by reacting the [NEt(4)](2)[Re(CO)(3)Br(3)] precursor with the β-diketone to generate the intermediate aqua complex fac-Re(CO)(3)(OO)(H(2)O) that was isolated and characterized, followed by replacement of the labile water by the monodentate ligand. All complexes were characterized by mass spectrometry, NMR and IR spectroscopies, and elemental analysis. In the case of complex 2, bearing imidazole as the monodentate ligand, X-ray analysis was possible. The chemistry was successfully transferred at (99m)Tc tracer level. The curcumin complexes 5 and 6, as well as their intermediate aqua complex 4, that bear potential for radiopharmaceutical applications due to the wide spectrum of pharmacological activity of curcumin, were successfully tested for selective staining of β-amyloid plaques of Alzheimer's disease. The fact that the complexes maintain the affinity of the mother compound curcumin for β-amyloid plaques prompts for further exploration of their chemistry and biological properties as radioimaging probes.

  11. Ion-pair triple helicates and mesocates self-assembled from ditopic 2,2 -bipyridine-bis(urea) ligands and Ni(II) and Fe(II) sulfate salts

    Energy Technology Data Exchange (ETDEWEB)

    Custelcean, Radu [ORNL; Bonnesen, Peter V [ORNL; Roach, Benjamin D [ORNL; Duncan, Nathan C [ORNL

    2012-01-01

    NiSO{sub 4} and FeSO{sub 4} self-assemble with heteroditopic ligands (L) comprising 2,2{prime}-bipyridine and o-phenylene-(bis)urea cation- and anion-binding sites, respectively, into [ML{sub 3}SO{sub 4}] (M = Ni{sup 2+}, Fe{sup 2+}) triple-stranded ion-pair helicates and mesocates.

  12. Ferrous Sulfate (Iron)

    Science.gov (United States)

    Ferrous sulfate provides the iron needed by the body to produce red blood cells. It is used ... Ferrous sulfate comes as regular, coated, and extended-release (long-acting) tablets; regular and extended-release capsules; ...

  13. The "in and out" of glucosamine 6-O-sulfation: the 6th sense of heparan sulfate.

    Science.gov (United States)

    El Masri, Rana; Seffouh, Amal; Lortat-Jacob, Hugues; Vivès, Romain R

    2016-11-03

    The biological properties of Heparan sulfate (HS) polysaccharides essentially rely on their ability to bind and modulate a multitude of protein ligands. These interactions involve internal oligosaccharide sequences defined by their sulfation patterns. Amongst these, the 6-O-sulfation of HS contributes significantly to the polysaccharide structural diversity and is critically involved in the binding of many proteins. HS 6-O-sulfation is catalyzed by 6-O-sulfotransferases (6OSTs) during biosynthesis, and it is further modified by the post-synthetic action of 6-O-endosulfatases (Sulfs), two enzyme families that remain poorly characterized. The aim of the present review is to summarize the contribution of 6-O-sulfates in HS structure/function relationships and to discuss the present knowledge on the complex mechanisms regulating HS 6-O-sulfation.

  14. Synthesis and characterization of mixed ligand complexes of bio-metals with pyrimidine nucleoside (uridine) and amino acids

    Indian Academy of Sciences (India)

    P Rabindra Reddy; A Mohan Reddy

    2000-12-01

    The mixed ligand complexes of Cu(II), Ni(II) and Co(II) with uridine and amino acids, L-alanine, L-phenylalanine and L-tryptophan were synthesized and characterized by elemental analysis, conductivity data, infrared spectra, electronic spectra and magnetic susceptibility data. In these complexes, the nucleoside (uridine) acts as a monodentate ligand coordinating through O(4) under the conditions of investigation, whereas the amino acids coordinate through the carboxylate oxygen and the amino nitrogen. Distorted octahedral geometry for Cu(II) and octahedral geometries for both Ni(II) and Co(II) are proposed.

  15. Sequestering uranium from UO2(CO3)3(4-) in seawater with amine ligands: density functional theory calculations.

    Science.gov (United States)

    Guo, Xiaojing; Huang, Liangliang; Li, Cheng; Hu, Jiangtao; Wu, Guozhong; Huai, Ping

    2015-06-14

    The polystyrene-supported primary amine -CH2NH2 has shown an at least 3-fold increase in uranyl capacity compared to a diamidoxime ligand on a polystyrene support. This study aims to understand the coordination of substitution complexes from UO2(CO3)3(4-) and amines using density functional theory calculations. Four kinds of amines (diethylamine (DEA), ethylenediamine (EDA), diethylenetriamine (DETA) and triethylenetetramine (TETA)) were selected because they belong to different classes and have different chain lengths. The geometrical structures, electronic structures and the thermodynamic stabilities of various substitution complexes, as well as the trends in their calculated properties were investigated at equilibrium. In these optimized complexes, DEA groups bind to uranyl as monodentate ligands; EDA groups serve as monodentate and bidentate ligands; DETA groups act as monodentate and tridentate ligands; while TETA groups serve as monodentate, bidentate and tridentate ligands. The thermodynamic analysis confirmed that the primary amines coordinate to uranyl more strongly than does the secondary amine. The stabilities of substitution complexes with primary amines were calculated to decrease with increasing chain length of the amine, except for UO2(L2)(2+). Of the complexes analyzed, only UO2L(CO3)2(2-) (L = EDA and DETA) and UO2L2CO3 (L = EDA) were predicted to form from the substitution reactions with UO2(CO3)3(4-) and protonated amines as reactants in aqueous solution. Amines were calculated to be comparable to, or sometimes weaker than, amidoximate in replacing CO3(2-) in UO2(CO3)3(4-) to coordinate to uranium. Therefore, the coordination mechanism, in which amines replace carbonates to bind to uranyl, is not primarily responsible for the experimentally observed 3-fold or greater increase in uranyl capacity of primary amines compared to a diamidoxime ligand. Based on the results of our calculations, we believe that the cation exchange mechanism, in which the

  16. Tyrosine Sulfation of Statherin

    Directory of Open Access Journals (Sweden)

    C. Kasinathan, N. Gandhi, P. Ramaprasad, P. Sundaram, N. Ramasubbu

    2007-01-01

    Full Text Available Tyrosylprotein sulfotransferase (TPST, responsible for the sulfation of a variety of secretory and membrane proteins, has been identified and characterized in submandibular salivary glands (William et al. Arch Biochem Biophys 1997; 338: 90-96. In the present study we demonstrate the sulfation of a salivary secretory protein, statherin, by the tyrosylprotein sulfotransferase present in human saliva. Optimum statherin sulfation was observed at pH 6.5 and at 20 mm MnCl2. Increase in the level of total sulfation was observed with increasing statherin concentration. The Km value of tyrosylprotein sulfotransferase for statherin was 40 μM. Analysis of the sulfated statherin product on SDS-polyacrylamide gel electrophoresis followed by autoradiography revealed 35S-labelling of a 5 kDa statherin. Further analysis of the sulfated statherin revealed the sulfation on tyrosyl residue. This study is the first report demonstrating tyrosine sulfation of a salivary secretory protein. The implications of this sulfation of statherin in hydroxyapatite binding and Actinomyces viscosus interactions are discussed.

  17. Transition Metal Complexes Coordinated by Water Soluble Phosphane Ligands: How Cyclodextrins Can Alter the Coordination Sphere?

    Directory of Open Access Journals (Sweden)

    Michel Ferreira

    2017-01-01

    Full Text Available The behaviour of platinum(II and palladium(0 complexes coordinated by various hydrosoluble monodentate phosphane ligands has been investigated by 31P{1H} NMR spectroscopy in the presence of randomly methylated β-cyclodextrin (RAME-β-CD. This molecular receptor can have no impact on the organometallic complexes, induce the formation of phosphane low-coordinated complexes or form coordination second sphere species. These three behaviours are under thermodynamic control and are governed not only by the affinity of RAME-β-CD for the phosphane but also by the phosphane stereoelectronic properties. When observed, the low-coordinated complexes may be formed either via a preliminary decoordination of the phosphane followed by a complexation of the free ligand by the CD or via the generation of organometallic species complexed by CD which then lead to expulsion of ligands to decrease their internal steric hindrance.

  18. Sensitization of visible and NIR emitting lanthanide(III) ions in noncentrosymmetric complexes of hexafluoroacetylacetone and unsubstituted monodentate pyrazole.

    Science.gov (United States)

    Ahmed, Zubair; Iftikhar, K

    2013-11-07

    A series of highly volatile eight-coordinate air and moisture stable lanthanide complexes of the type [Ln(hfaa)3(L)2] (Ln = Pr (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Ho (7), Er (8), Tm (9), and Yb (10); hfaa = anion of hexafluoroacetylacetone and L = pyrazole) have been synthesized and characterized by elemental analysis, IR, ESI-MS(+), and NMR studies. Single-crystal X-ray structures have been determined for the Eu(III) and Dy(III) complexes. These complexes crystallize in the monoclinic space group P2(1)/c. The lanthanide ion in each of these complexes is eight-coordinate with six oxygen atoms from three hfaa and two N-atoms from two pyrazole units, forming a coordination polyhedron best describable as a distorted square antiprism. The NMR spectra reveal that both the pyrazole units remain attached to the metal in solution and the β-diketonate and pyrazole protons are shifted in opposite directions in the case of paramagnetic complexes. The lanthanide-induced chemical shifts are dipolar in nature. The hypersensitive transitions of Nd(III), Ho(III), and Er(III) are sensitive to the environment (solvent), which is reflected by the oscillator strength and band shape of these transitions. The band shape due to the hypersensitive transition of Nd(III) in noncoordinating chloroform and dichloromethane is similar to those of the typical eight-coordinate Nd(III) β-diketonate complexes. The quantum yield and lifetime of Pr(III), Eu(III), Tb(III), Dy(III), and Tm(III) in visible and Pr(III), Nd(III), Dy(III), Ho(III), Er(III) Tm(III), and Yb(III) in the NIR region are sizable. The environment around these metal ions is asymmetric, which leads to increased radiative rates and luminescence efficiencies. The quantum yield of the complexes reveal that ligand-to-metal energy transfer follows the order Eu(III) > Tb(III) ≫ Pr(III) > Dy(III) > Tm(III). Both ligands (hfaa and pyrazole) are good sensitizers for all the visible and NIR emitters effectively, except for Tb

  19. The ceric sulfate dosimeter

    DEFF Research Database (Denmark)

    Bjergbakke, Erling

    1970-01-01

    The process employed for the determination of absorbed dose is the reduction of ceric ions to cerous ions in a solution of ceric sulfate and cerous sulfate in 0.8N sulfuric acid: Ce4+→Ce 3+ The absorbed dose is derived from the difference in ceric ion concentration before and after irradiation...

  20. Heparan sulfate biosynthesis

    DEFF Research Database (Denmark)

    Multhaupt, Hinke A B; Couchman, John R

    2012-01-01

    Heparan sulfate is perhaps the most complex polysaccharide known from animals. The basic repeating disaccharide is extensively modified by sulfation and uronic acid epimerization. Despite this, the fine structure of heparan sulfate is remarkably consistent with a particular cell type. This suggests...... that the synthesis of heparan sulfate is tightly controlled. Although genomics has identified the enzymes involved in glycosaminoglycan synthesis in a number of vertebrates and invertebrates, the regulation of the process is not understood. Moreover, the localization of the various enzymes in the Golgi apparatus has......-quality resolution of the distribution of enzymes. The EXT2 protein, which when combined as heterodimers with EXT1 comprises the major polymerase in heparan sulfate synthesis, has been studied in depth. All the data are consistent with a cis-Golgi distribution and provide a starting point to establish whether all...

  1. Utilization of mixed ligands to construct diverse Ni(II)-coordination polymers based on terphenyl-2,2‧,4,4‧-tetracarboxylic acid and varied N-donor co-ligands

    Science.gov (United States)

    Wang, Chao; Zhao, Jun; Xia, Liang; Wu, Xue-Qian; Wang, Jian-Fang; Dong, Wen-Wen; Wu, Ya-Pan

    2016-06-01

    Three new coordination polymers, namely, {[Ni(H2L)(bix)(H2O)2]·2h2O}n (1), {[Ni(HL)(Hdpa)(H2O)2]·H2O}n (2), {[Ni(L)0.5(bpp)(H2O)]·H2O}n (3) (H4L=terphenyl-2,2‧,4,4‧-tetracarboxylic acid; bix=1,4-bis(imidazol-1-ylmethyl)benzene; dpa =4,4‧-dipyridylamine; bpp=1,3-bis(4-pyridyl)propane), based on rigid H4L ligand and different N-donor co-ligands, have been synthesized under hydrothermal conditions. Compound 1 features a 3D 4-connected 66-dia-type framework with H4L ligand adopts a μ2-bridging mode with two symmetry-related carboxylate groups in μ1-η1:η0 monodentate mode. Compound 2 displays a 1D [Ni(HL)(Hdpa)]n ribbon chains motif, in which the H4L ligand adopts a μ2-bridging mode with two carboxylate groups in μ1-η1:η1 and μ1-η1:η0 monodentate modes, while 3 possesses a (4,4)-connected 3D frameworks with bbf topology, with H4L ligand displays a μ4-bridging coordination mode. The H4L ligand displays not only different deprotonated forms but also diverse coordination modes and conformations. The structural diversities among 1-3 have been carefully discussed, and the roles of N-donor co-ligands in the self-assembly of coordination polymers have been well documented.

  2. Direct Sulfation of Limestone

    DEFF Research Database (Denmark)

    Hu, Guilin; Dam-Johansen, Kim; Wedel, Stig

    2007-01-01

    The direct sulfation of limestone was studied in a laboratory fixed-bed reactor. It is found that the direct sulfation of limestone involves nucleation and crystal grain growth of the solid product (anhydrite). At 823 K and at low-conversions (less than about 0.5 %), the influences of SO2, O-2...... and CO2 on the direct sulfation of limestone corresponds to apparent reaction orders of about 0.2, 0.2 and -0.5, respectively. Water is observed to promote the sulfation reaction and increase the apparent reaction orders of SO2 and O-2. The influence of O-2 at high O-2 concentrations (> about 15...... %) becomes negligible. In the temperature interval from 723 K to 973 K, an apparent activation energy of about 104 kJ/mol is observed for the direct sulfation of limestone. At low temperatures and low conversions, the sulfation process is most likely under mixed control by chemical reaction and solid...

  3. Chelate vs monodentate amine effects. Direct comparison of bis(acetato)amminedichloro(cyclohexylamine)platinum(IV) (JM216) with its N-cyclohexyl-1,3-propanediamine analogue

    Science.gov (United States)

    Lee, Young-A.; Kang, Shin Won; Park, Jong Yul; Jung, Ok-Sang

    2003-10-01

    In order to investigate the chelate effects on physicochemical properties including antitumor activity, new cis, trans, cis,-[Pt IVCl 2L 2(chpda)] complexes (L=OH, OCOCH 3; chpda= N-cyclohexyl-1,3-propanediamine) have been synthesized and characterized. The crystal structure of cis, trans, cis-[Pt IVCl 2(OCOCH 3) 2(chpda)] (monoclinic P2 1/ a, a=7.947(1), b=22.753(11), and c=10.581(3) Å, β=110.70(2)°, V=1790(1) Å 3, Z=4, R=0.0534) shows that the platinum(IV) center adopts a typical octahedral arrangement with two acetate groups in a trans position. The pattern and strength of the intramolecular hydrogen bonds are delicately different from those of JM216. Both in vitro and in vivo (oral) cytotoxicities on mouse leukemia L1210 cell line indicate that the activity of chpda chelate analogue is not better than that of the corresponding compound with two monodentate amines (JM216).

  4. Half-sandwich pentamethylcyclopentadienyl group 9 metal complexes of 2-aminopyridyl ligands: Synthesis, spectral and molecular study

    Indian Academy of Sciences (India)

    Mahesh Kalidasan; Scott Forbes; Yurij Mozharivskyj; Mohan Rao Kollipara

    2015-06-01

    Thereaction of [Cp*M(-Cl)Cl]2 (M = Rh, Ir) with 2-aminopyridyl based ligands lead to the formation of mononuclear neutral complexes of general formula [Cp*MCl2(L)] {where L1= 2-aminopyridine, L2= 2-amino-3-picoline, L3= 2-amino-3-nirtopyridine, and L4= 2-amino-3-pyridine carboxyaldehyde}. The complexes have been characterized by FT-IR, UV-Vis, 1H-13C NMR and mass spectroscopic methods. X-ray crystallographic studies of the complexes have shown typical piano-stool geometry around the metal centre in which 2-aminopyridyl ligand acts as an N-monodentate ligand and the amino functionality is not involved in metal coordination. The intra/intermolecular arrangement is due to hydrogen bonding.

  5. Selective oxoanion separation using a tripodal ligand

    Energy Technology Data Exchange (ETDEWEB)

    Custelcean, Radu; Moyer, Bruce A.; Rajbanshi, Arbin

    2016-02-16

    The present invention relates to urea-functionalized crystalline capsules self-assembled by sodium or potassium cation coordination and by hydrogen-bonding water bridges to selectively encapsulate tetrahedral divalent oxoanions from highly competitive aqueous alkaline solutions and methods using this system for selective anion separations from industrial solutions. The method involves competitive crystallizations using a tripodal tris(urea) functionalized ligand and, in particular, provides a viable approach to sulfate separation from nuclear wastes.

  6. Template synthesis, characterization and antimicrobial activity of some new complexes with isonicotinoyl hydrazone ligands

    Directory of Open Access Journals (Sweden)

    LIVIU MITU

    2009-09-01

    Full Text Available Complexes of Cu(II, Ni(II, Co(II with the 9-anthraldehyde iso-nicotinoyl hydrazone ligand (HL1 and the 3,5-di-tert-butyl-4-hydroxy-benzaldehyde isonicotinoyl hydrazone ligand (H2L2 were synthesized by the template method. The complexes were characterized by analytical analysis, IR, UV-Vis and ESR spectroscopy, magnetic measurements, conductometry and thermal analysis and the two ligands by 1H-NMR spectroscopy. From the elemental analysis, 1:2 (metal:ligand stoichiometry for the complexes of Cu(II, Ni(II with the ligands HL1 and H2L2 and 1:1 (metal:ligand stoichiometry for the complex of Co(II with the ligand HL1 are proposed. The molar conductance data showed that the complexes are non-electrolytes. The magnetic susceptibility results coupled with the electronic and ESR spectra suggested a distorted octahedral geometry for the complexes Ni(II/HL1, Ni(II/H2L2 and Cu(II/H2L2, a tetrahedral stereochemistry for the complex Cu/HL1 and a square-planar geometry for the complex Co/HL1. The IR spectra demonstrated the bidentate coordination of the ligands HL1 and H2L2 by the O=C amide oxygen and the azomethine nitrogen, as well as monodentate coordination of the ligand HL1 by the azomethine nitrogen in the Cu(IIcomplex. The antibacterial activity of the ligands and their metallic complexes were tested against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae.

  7. Secondary interactions or ligand scrambling? Subtle steric effects govern the iridium(I) coordination chemistry of phosphoramidite ligands.

    Science.gov (United States)

    Osswald, Tina; Rüegger, Heinz; Mezzetti, Antonio

    2010-01-25

    The like and unlike isomers of phosphoramidite (P*) ligands are found to react differently with iridium(I), which is a key to explaining the apparently inconsistent results obtained by us and other research groups in a variety of catalytic reactions. Thus, the unlike diastereoisomer (aR,S,S)-[IrCl(cod)(1 a)] (2 a; cod=1,5-cyclooctadiene, 1 a=(aR,S,S)-(1,1'-binaphthalene)-2,2'-diyl bis(1-phenylethyl)phosphoramidite) forms, upon chloride abstraction, the monosubstituted complex (aR,S,S)-[Ir(cod)(1,2-eta-1 a,kappaP)](+) (3 a), which contains a chelating P* ligand that features an eta(2) interaction between a dangling phenyl group and iridium. Under analogous conditions, the like analogue (aR,R,R)-1 a' gives the disubstituted species (aR,R,R)-[Ir(cod)(1 a',kappaP)(2)](+) (4 a') with monodentate P* ligands. The structure of 3 a was assessed by a combination of X-ray and NMR spectroscopic studies, which indicate that it is the configuration of the binaphthol moiety (and not that of the dangling benzyl N groups) that determines the configuration of the complex. The effect of the relative configuration of the P* ligand on its iridium(I) coordination chemistry is discussed in the context of our preliminary catalytic results and of apparently random results obtained by other groups in the iridium(I)-catalyzed asymmetric allylic alkylation of allylic acetates and in rhodium(I)-catalyzed asymmetric cycloaddition reactions. Further studies with the unlike ligand (aS,R,R)-(1,1'-binaphthalene)-2,2'-diyl bis{[1-(1-naphthalene-1-yl)ethyl]phosphoramidite} (1 b) showed a yet different coordination mode, that is, the eta(4)-arene-metal interaction in (aS,R,R)-[Ir(cod)(1,2,3,4-eta-1 b,kappaP)](+) (3 b).

  8. Rationally designed fluorescently labeled sulfate-binding protein mutants: evaluation in the development of a sensing system for sulfate

    Science.gov (United States)

    Shrestha, Suresh; Salins, Lyndon L E.; Mark Ensor, C.; Daunert, Sylvia

    2002-01-01

    Periplasmic binding proteins from E. coli undergo large conformational changes upon binding their respective ligands. By attaching a fluorescent probe at rationally selected unique sites on the protein, these conformational changes in the protein can be monitored by measuring the changes in fluorescence intensity of the probe which allow the development of reagentless sensing systems for their corresponding ligands. In this work, we evaluated several sites on bacterial periplasmic sulfate-binding protein (SBP) for attachment of a fluorescent probe and rationally designed a reagentless sensing system for sulfate. Eight different mutants of SBP were prepared by employing the polymerase chain reaction (PCR) to introduce a unique cysteine residue at a specific location on the protein. The sites Gly55, Ser90, Ser129, Ala140, Leu145, Ser171, Val181, and Gly186 were chosen for mutagenesis by studying the three-dimensional X-ray crystal structure of SBP. An environment-sensitive fluorescent probe (MDCC) was then attached site-specifically to the protein through the sulfhydryl group of the unique cysteine residue introduced. Each fluorescent probe-conjugated SBP mutant was characterized in terms of its fluorescence properties and Ser171 was determined to be the best site for the attachment of the fluorescent probe that would allow for the development of a reagentless sensing system for sulfate. Three different environment-sensitive fluorescent probes (1,5-IAEDANS, MDCC, and acylodan) were studied with the SBP171 mutant protein. A calibration curve for sulfate was constructed using the labeled protein and relating the change in the fluorescence intensity with the amount of sulfate present in the sample. The detection limit for sulfate was found to be in the submicromolar range using this system. The selectivity of the sensing system was demonstrated by evaluating its response to other anions. A fast and selective sensing system with detection limits for sulfate in the

  9. Controlling barium sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Greenley, R.

    Even though for several years success has been realized in controlling barium sulfate scale deposition in relatively shallow, low pressure oil wells--by squeezing an organic phosphonate scale inhibitor into the producing zone--barium sulfate scale depositon in deep, high pressure/high temperature wells usually meant an expensive workover operation. A case history of a deep (16,000 ft) well in St. Mary Parish, Louisiana, and the scale inhibitor squeeze operation are described. Based on the successful results obtained in treating this well, a generalized treating procedure for combating downhole scale deposition in high pressure/high temperature gas wells is presented. Formation squeezing with such an inhibitor represents a significant breakthrough for the oil and gas industry.

  10. Sulfation of chondroitin. Specificity, degree of sulfation, and detergent effects with 4-sulfating and 6-sulfating microsomal systems

    Energy Technology Data Exchange (ETDEWEB)

    Sugumaran, G.; Silbert, J.E.

    1988-04-05

    Microsomal preparations from chondroitin 6-sulfate-producing chick embryo epiphyseal cartilage, and from chondroitin 4-sulfate-producing mouse mastocytoma cells, were incubated with UDP-(14C)glucuronic acid and UDP-N-acetylgalactosamine to form non-sulfated proteo(14C)chondroitin. Aliquots of the incubations were then incubated with 3'-phosphoadenylylphosphosulfate (PAPS) in the presence or absence of various detergents. In the absence of detergents, there was good sulfation of this endogenous proteo(14C)chondroitin by the original microsomes from both sources. Detergents, with the exception of Triton X-100, markedly inhibited sulfation in the mast cell system but not in the chick cartilage system. These results indicate that sulfation and polymerization are closely linked on cell membranes and that in some cases this organization can be disrupted by detergents. When aliquots of the original incubation were heat inactivated, and then reincubated with new microsomes from chick cartilage and/or mouse mastocytoma cells plus PAPS, there was no significant sulfation of this exogenous proteo(14C) chondroitin with either system unless Triton X-100 was added. Sulfation of exogenous chondroitin and chondroitin hexasaccharide was compared with sulfation of endogenous and exogenous proteo(14C)chondroitin. Sulfate incorporation into hexasaccharide and chondroitin decreased as their concentrations (based on uronic acid) approached that of the proteo(14C)chondroitin. At the same time, the degree of sulfation in percent of substituted hexosamine increased. However, the degree of sulfation did not reach that of the endogenous proteo(14C)chondroitin. Hexasaccharide and chondroitin sulfation were stimulated by the presence of Triton X-100. However, in contrast to the exogenous proteo(14C)chondroitin, there was some sulfation of hexasaccharide and chondroitin in the absence of this detergent.

  11. Off limits: sulfate below the sulfate-methane transition

    Science.gov (United States)

    Brunner, Benjamin; Arnold, Gail; Røy, Hans; Müller, Inigo; Jørgensen, Bo

    2016-07-01

    One of the most intriguing recent discoveries in biogeochemistry is the ubiquity of cryptic sulfur cycling. From subglacial lakes to marine oxygen minimum zones, and in marine sediments, cryptic sulfur cycling - the simultaneous sulfate consumption and production - has been observed. Though this process does not leave an imprint in the sulfur budget of the ambient environment - thus the term cryptic - it may have a massive impact on other element cycles and fundamentally change our understanding of biogeochemical processes in the subsurface. Classically, the sulfate-methane transition (SMT) in marine sediments is considered to be the boundary that delimits sulfate reduction from methanogenesis as the predominant terminal pathway of organic matter mineralization. Two sediment cores from Aarhus Bay, Denmark reveal the constant presence of sulfate (generally 0.1 to 0.2 mM) below the SMT. The sulfur and oxygen isotope signature of this deep sulfate (34S = 18.9‰, 18O = 7.7‰) was close to the isotope signature of bottom-seawater collected from the sampling site (34S = 19.8‰, 18O = 7.3‰). In one of the cores, oxygen isotope values of sulfate at the transition from the base of the SMT to the deep sulfate pool (18O = 4.5‰ to 6.8‰) were distinctly lighter than the deep sulfate pool. Our findings are consistent with a scenario where sulfate enriched in 34S and 18O is removed at the base of the SMT and replaced with isotopically light sulfate below. Here, we explore scenarios that explain this observation, ranging from sampling artifacts, such as contamination with seawater or auto-oxidation of sulfide - to the potential of sulfate generation in a section of the sediment column where sulfate is expected to be absent which enables reductive sulfur cycling, creating the conditions under which sulfate respiration can persist in the methanic zone.

  12. Heparan sulfate chains from glypican and syndecans bind the Hep II domain of fibronectin similarly despite minor structural differences

    DEFF Research Database (Denmark)

    Tumova, S; Woods, A; Couchman, J R

    2000-01-01

    of syndecan-4 correlates with a distinct heparan sulfate structure, we have analyzed heparan sulfate chains from the different surface proteoglycans of a single fibroblast strain and compared their ability to bind the Hep II domain of fibronectin, a ligand known to promote focal adhesion formation through...... syndecan-4. Despite distinct molecular masses of glypican and syndecan glycosaminoglycans and minor differences in disaccharide composition and sulfation pattern, the overall proportion and distribution of sulfated regions and the affinity for the Hep II domain were similar. Therefore, adhesion regulation...

  13. Mechanisms and origins of switchable chemoselectivity of Ni-catalyzed C(aryl)-O and C(acyl)-O activation of aryl esters with phosphine ligands.

    Science.gov (United States)

    Hong, Xin; Liang, Yong; Houk, K N

    2014-02-05

    Many experiments have shown that nickel with monodentate phosphine ligands favors the C(aryl)-O activation over the C(acyl)-O activation for aryl esters. However, Itami and co-workers recently discovered that nickel with bidentate phosphine ligands can selectively activate the C(acyl)-O bond of aryl esters of aromatic carboxylic acids. The chemoselectivity with bidentate phosphine ligands can be switched back to C(aryl)-O activation when aryl pivalates are employed. To understand the mechanisms and origins of this switchable chemoselectivity, density functional theory (DFT) calculations have been conducted. For aryl esters, nickel with bidentate phosphine ligands cleaves C(acyl)-O and C(aryl)-O bonds via three-centered transition states. The C(acyl)-O activation is more favorable due to the lower bond dissociation energy (BDE) of C(acyl)-O bond, which translates into a lower transition-state distortion energy. However, when monodentate phosphine ligands are used, a vacant coordination site on nickel creates an extra Ni-O bond in the five-centered C(aryl)-O cleavage transition state. The additional interaction energy between the catalyst and substrate makes C(aryl)-O activation favorable. In the case of aryl pivalates, nickel with bidentate phosphine ligands still favors the C(acyl)-O activation over the C(aryl)-O activation at the cleavage step. However, the subsequent decarbonylation generates a very unstable tBu-Ni(II) intermediate, and this unfavorable step greatly increases the overall barrier for generating the C(acyl)-O activation products. Instead, the subsequent C-H activation of azoles and C-C coupling in the C(aryl)-O activation pathway are much easier, leading to the observed C(aryl)-O activation products.

  14. Assembly of tetra, di and mononuclear molecular cadmium phosphonates using 2,4,6-triisopropylphenylphosponic acid and ancillary ligands.

    Science.gov (United States)

    Chandrasekhar, Vadapalli; Sasikumar, Palani; Boomishankar, Ramamoorthy

    2008-10-14

    The reaction of ArPO(3)H(2) (Ar = 2,4,6-iPr(3)-C(6)H(2)) with Cd(CH(3)COO)(2).2H(2)O using various co-ligands such as methanol, dimethylformamide (DMF) and 3,5-dimethylpyrazole (DMPZH) resulted in the formation of tetranuclear assemblies [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(CH(3)OH)(4)].3(CH(3)OH) (1), [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(DMF)(4)].3(DMF) (2) and [Cd(4)(ArPO(3))(2)(ArPO(3)H)(4)(DMF)(2)(DMPZH)(2)].2(DMF).2(H(2)O) (3). In all of these compounds the tetranuclear cadmium array, containing two five-coordinate and two six-coordinate cadmium atoms, is held together by two mu(4) capping [ArPO(3)](2-) and four anisobidentate mu(2) [ArPO(2)(OH)](-) ligands. Each cadmium atom is bound to an additional ancillary ligand. The reaction of ArPO(3)H(2) with Cd(CH(3)COO)(2).2H(2)O in the presence of the chelating ligand 2,2'-bipyridine (bipy) leads to the exclusive formation of the dinuclear assembly [Cd(2)(ArPO(3)H)(4)(bipy)(2)].(CH(3)OH)(H(2)O) (4). The latter contains an eight-membered Cd(2)P(2)O(4) inorganic ring formed as a result of the bridging coordination action of two anisobidentate mu(2) [ArPO(2)(OH)](-) ligands. Each cadmium atom is bound by one chelating bipy and one monodentate [ArPO(2)(OH)](-) ligands. Use of four equivalents of 3,5-dimethylpyrazole leads to the formation of the mononuclear derivative [Cd(ArPO(3)H)(2)(DMPZH)(4)] (5). The molecular structure of the latter comprises of a central cadmium atom surrounded by six monodentate ligands. Four of these are neutral pyrazole ligands that occupy the equatorial plane; the remaining two are anionic phosphinate ligands which are present trans to each other. The thermal analysis of 1 and 4 reveals that the char residue obtained at 600 degrees C consists predominantly of Cd(2)P(2)O(7).

  15. 2-Amino-4-hydroxyethylaminoanisole sulfate

    DEFF Research Database (Denmark)

    Madsen, Jakob T; Andersen, Klaus E

    2016-01-01

    positive patch test reactions to the coupler 2-amino-4-hydroxyethylaminoanisole sulfate 2% pet. from 2005 to 2014. METHODS: Patch test results from the Allergen Bank database for eczema patients patch tested with 2-amino-4-hydroxyethylaminoanisole sulfate 2% pet. from 2005 to 2014 were reviewed. RESULTS......: A total of 902 dermatitis patients (154 from the dermatology department and 748 from 65 practices) were patch tested with amino-4-hydroxyethylaminoanisole sulfate 2% pet. from 2005 to 2014. Thirteen (1.4%) patients had a positive patch test reaction. Our results do not indicate irritant reactions....... CONCLUSIONS: 2-Amino-4-hydroxyethylaminoanisole sulfate is a new but rare contact allergen....

  16. Tandem Mass Spectrometry of Heparan Sulfate Negative Ions: Sulfate Loss Patterns and Chemical Modification Methods for Improvement of Product Ion Profiles

    Science.gov (United States)

    Shi, Xiaofeng; Huang, Yu; Mao, Yang; Naimy, Hicham; Zaia, Joseph

    2012-09-01

    Heparan sulfate (HS) is a polysaccharide modified with sulfation, acetylation, and epimerization that enable its binding with protein ligands and regulation of important biological processes. Tandem mass spectrometry has been employed to sequence linear biomolecules e.g., proteins and peptides. However, its application in structural characterization of HS is limited due to the neutral loss of sulfate (SO3) during collisional induced dissociation (CID). In this report, we studied the dissociation patterns of HS disaccharides and demonstrate that the N-sulfate (N-S) bond is especially facile during CID. We identified factors that influence the propensities of such losses from precursor ions and proposed a Free Proton Index (FPI) to help select ions that are able to produce meaningful backbone dissociations. We then investigated the thermodynamics and kinetics of SO3 loss from sulfates that are protonated, deprotonated, and metal-adducted using density functional theory computations. The calculations showed that sulfate loss from a protonated site was much more facile than that from a deprotonated or metal-adducted site. Further, the loss of SO3 from N-sulfate was energetically favored by 3-8 kcal/mol in transition states relative to O-sulfates, making it more prone to this process by a substantial factor. In order to reduce the FPI, representing the number of labile sulfates in HS native chains and oligosaccharides, we developed a series of chemical modifications to selectively replace the N-sulfates of the glucosamine with deuterated acetyl group. These modifications effectively reduced the sulfate density on the HS oligosaccharides and generated considerably more backbone dissociation using on-line LC/tandem MS.

  17. 21 CFR 184.1315 - Ferrous sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ferrous sulfate. 184.1315 Section 184.1315 Food and... Substances Affirmed as GRAS § 184.1315 Ferrous sulfate. (a) Ferrous sulfate heptahydrate (iron (II) sulfate... as pale, bluish-green crystals or granules. Progressive heating of ferrous sulfate heptahydrate...

  18. Mixed Ligand Complexes of N-Methyl-N-phenyl Dithiocarbamate: Synthesis, Characterisation, Antifungal Activity, and Solvent Extraction Studies of the Ligand.

    Science.gov (United States)

    Ekennia, Anthony C; Onwudiwe, Damian C; Ume, Cyril; Ebenso, Eno E

    2015-01-01

    A series of mixed ligand dithiocarbamate complexes with a general formula [ML2(py)2], where M = Mn(II), Co(II), Ni(II), and Cu(II), py = pyridine, and L = N-methyl-N-phenyl dithiocarbamate have been prepared and characterised by elemental analysis, FTIR and Uv spectroscopy, magnetic moment, and thermogravimetric and conductance analysis. The infrared spectra showed that symmetrical bidentate coordination occurred with the dithiocarbamate moiety through the sulfur atoms, while neutral monodentate coordination occurred through the nitrogen atom for the pyridine molecule in the complexes. The electronic spectra, elemental analysis, and magnetic moment results proved that the complexes adopted octahedral geometry. The conductance measurement showed that the complexes are nonelectrolytes proving their nonionic nature. The compounds were screened for three human pathogenic fungi: Aspergillus flavus, Aspergillus niger, and Candida albicans. The cobalt complex showed the best antifungal activity among the test compounds. Liquid-liquid extractive abilities of the ligand towards copper and nickel ions in different solvent media were investigated. The ligand showed a strong binding affinity towards the metals ions with an extractive efficiency of about 99%.

  19. Sulfate transport in toad skin

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Simonsen, K

    1988-01-01

    1. In short-circuited toad skin preparations exposed bilaterally to NaCl-Ringer's containing 1 mM SO2(-4), influx of sulfate was larger than efflux showing that the skin is capable of transporting sulfate actively in an inward direction. 2. This active transport was not abolished by substituting ...

  20. Interaction of PACls with sulfate

    Institute of Scientific and Technical Information of China (English)

    XU Yi; WANG Dong-Sheng; TANG Hong-Xiao

    2004-01-01

    This article discusses the influential factors on Al13 separation considering the interaction of sulfate with various polyaluminum chloride(PACl). The experimental results showed that the basicity(B=[OH]/[Al]), the concentration of PACl and Al/SO4 ratio exhibited significant roles in the PACl-sulfate reaction. It indicated that different species in various PACl underwent different reaction pathway with sulfate. The Alc, colloidal species, formed precipitation quickly with sulfate, while Alb, oligomers and polymers, undergoes slow crystallization. And Ala, monomers, reacts with sulfate to form soluble complexes. The kinetic difference of reaction made it possible to realize the separation of Alb and further purification. The decrease of Ala resulted in the limit of ferron method was also mentioned.

  1. Understanding the complexation of Eu3 + with potential ligands used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle: A luminescence investigation

    Science.gov (United States)

    Sengupta, Arijit; Kadam, R. M.

    2017-02-01

    A systematic photoluminescence based investigation was carried out to understand the complexation of Eu3 + with different ligands (TBP: tri-n-butyl phosphate, DHOA: di-n-hexyl octanamide, Cyanex 923: tri-n-alkyl phosphine oxide and Cyanex 272: Bis (2,4,4 trimethyl) pentyl phosphinic acid) used for preferential separation of lanthanides and actinides in various stages of nuclear fuel cycle. In case of TBP and DHOA complexes, 3 ligand molecules coordinated in monodentate fashion and 3 nitrate ion in bidentate fashion to Eu3 + to satisfy the 9 coordination of Eu. In case of Cyanex 923 and Cyanex 272 complexes, 3 ligand molecules, 3 nitrate ion and 3 water molecules coordinated to Eu3 + in monodentate fashion. The Eu complexes of TBP and DHOA were found to have D3h local symmetry while that for Cyanex 923 and Cyanex 272 were C3h. Judd-Ofelt analysis of these systems revealed that the covalency of Eusbnd O bond followed the trend DHOA > TBP > Cyanex 272 > Cyanex 923. Different photophysical properties like radiative and non-radiative life time, branching ratio for different transitions, magnetic and electric dipole moment transition probabilities and quantum efficiency were also evaluated and compared for these systems. The magnetic dipole transition probability was found to be almost independent of ligand field perturbation while electric dipole transition probability for 5D0-7F2 transition was found to be hypersensitive with ligand field with a trend DHOA > TBP > Cyanex 272 > Cyanex 923. Supplementary Table 2: Determination of inner sphere water molecules from the different empirical formulae reported in the literature.

  2. Mobilization of stem/progenitor cells by sulfated polysaccharides does not require selectin presence.

    Science.gov (United States)

    Sweeney, E A; Priestley, G V; Nakamoto, B; Collins, R G; Beaudet, A L; Papayannopoulou, T

    2000-06-06

    Employing carbohydrate ligands, which have been extensively used to block selectin function in vitro and in vivo, we have examined the involvement of such ligands in stem/progenitor cell mobilization in mice and monkeys. We found that sulfated fucans, branched and linear, are capable of increasing mature white cells in the periphery and mobilizing stem/progenitor cells of all classes (up to 32-fold) within a few hours posttreatment in a dose-dependent manner. To elicit the effect, the presence of sulfate groups was necessary, yet not sufficient, as certain sulfated hexosamines tested (chondroitin sulfates A or B) were ineffective. Significant mobilization of stem/progenitor cells and leukocytosis was elicited in selectin-deficient mice (L(-/-), PE(-/-), or LPE(-/-)) similar to that of wild-type controls, suggesting that the mode of action of sulfated fucans is not through blockade of known selectins. Other mechanisms have been entertained, in particular, the release of chemokines/cytokines, including some previously implicated in mobilization. Significant increases were documented in the levels of seven circulating chemokines/cytokines within a few hours after fucan sulfate treatment and support such a proposition. Additionally, an increase was noted in plasma metalloproteinase (MMP) 9, which might independently contribute to the mobilization process by enzymatically facilitating chemokine/cytokine release. Mobilization by sulfated polysaccharides provides a distinct paradigm in the mobilization process and uncovers an additional novel in vivo biological role for sulfated glycans. As similarly sulfated compounds were ineffective in vivo, the data also underscore the fact that polysaccharides with similar structures may elicit diverse in vivo effects.

  3. Combinatorial expression patterns of heparan sulfate sulfotransferases in zebrafish: II. The 6-O-sulfotransferase family.

    Science.gov (United States)

    Cadwallader, Adam B; Yost, H Joseph

    2006-12-01

    Heparan sulfate (HS) is an unbranched chain of repetitive disaccharides, which specifically binds ligands when attached to the cell surface or secreted extracellularly. HS chains contain sulfated domains termed the HS fine structure, which gives HS specific binding affinities for extracellular ligands. HS 6-O-sulfotransferases (6-OST) catalyze the transfer of sulfate groups to the 6-O position of glucosamine residues of HS. We report here the characterization and developmental expression analysis of the 6-OST gene family in the zebrafish. The zebrafish 6-OST gene family consists of four conserved vertebrate orthologues, including a gene duplication specific to zebrafish. We examined the mRNA expression patterns in several tissues/organs throughout early zebrafish development, including early cleavage stages, eyes, somites, brain, internal organ primordial, and pectoral fin development. Members of the 6-OST gene family have spatially and temporally distinct restricted expression, suggesting in vivo functional differences exist between members of this family.

  4. Antitumor and antiparasitic activity of novel ruthenium compounds with polycyclic aromatic ligands.

    Science.gov (United States)

    Miserachs, Helena Guiset; Cipriani, Micaella; Grau, Jordi; Vilaseca, Marta; Lorenzo, Julia; Medeiros, Andrea; Comini, Marcelo A; Gambino, Dinorah; Otero, Lucía; Moreno, Virtudes

    2015-09-01

    Five novel ruthenium(II)-arene complexes with polycyclic aromatic ligands were synthesized, comprising three compounds of the formula [RuCl(η(6)-p-cym)(L)][PF6], where p-cym = 1-isopropyl-4-methylbenzene and L are the bidentate aromatic ligands 1,10-phenanthroline-5,6-dione, 1, 5-amine-1,10-phenanthroline, 4, or 5,6-epoxy-5,6-dihydro-phenanthroline, 5. In the other two complexes [RuCl2(η(6)-p-cym)(L')], the metal is coordinated to a monodentate ligand L', where L' is phenanthridine, 2, or 9-carbonylanthracene, 3. All compounds were fully characterized by mass spectrometry and elemental analysis, as well as NMR and IR spectroscopic techniques. Obtained ruthenium compounds as well as their respective ligands were tested for their antiparasitic and antitumoral activities. Even though all compounds showed lower Trypanosoma brucei activity than the free ligands, they also resulted less toxic on mammalian cells. Cytotoxicity assays on HL60 cells showed a moderate antitumoral activity for all ruthenium compounds. Compound 1 was the most potent antitumoral (IC50 = 1.26±0.78 μM) and antiparasitic (IC50 = 0.19 ± 0.05 μM) agent, showing high selectivity towards the parasites (selectivity index >100). As complex 1 was the most promising antitumoral compound, its interaction with ubiquitin as potential target was also studied. In addition, obtained ruthenium compounds were found to bind DNA, and they are thought to interact with this macromolecule mainly through intercalation of the aromatic ligand.

  5. Heparan sulfate and cell division

    Directory of Open Access Journals (Sweden)

    Porcionatto M.A.

    1999-01-01

    Full Text Available Heparan sulfate is a component of vertebrate and invertebrate tissues which appears during the cytodifferentiation stage of embryonic development. Its structure varies according to the tissue and species of origin and is modified during neoplastic transformation. Several lines of experimental evidence suggest that heparan sulfate plays a role in cellular recognition, cellular adhesion and growth control. Heparan sulfate can participate in the process of cell division in two distinct ways, either as a positive or negative modulator of cellular proliferation, or as a response to a mitogenic stimulus.

  6. p-Cresyl Sulfate

    Directory of Open Access Journals (Sweden)

    Tessa Gryp

    2017-01-01

    Full Text Available If chronic kidney disease (CKD is associated with an impairment of kidney function, several uremic solutes are retained. Some of these exert toxic effects, which are called uremic toxins. p-Cresyl sulfate (pCS is a prototype protein-bound uremic toxin to which many biological and biochemical (toxic effects have been attributed. In addition, increased levels of pCS have been associated with worsening outcomes in CKD patients. pCS finds its origin in the intestine where gut bacteria metabolize aromatic amino acids, such as tyrosine and phenylalanine, leading to phenolic end products, of which pCS is one of the components. In this review we summarize the biological effects of pCS and its metabolic origin in the intestine. It appears that, according to in vitro studies, the intestinal bacteria generating phenolic compounds mainly belong to the families Bacteroidaceae, Bifidobacteriaceae, Clostridiaceae, Enterobacteriaceae, Enterococcaceae, Eubacteriaceae, Fusobacteriaceae, Lachnospiraceae, Lactobacillaceae, Porphyromonadaceae, Staphylococcaceae, Ruminococcaceae, and Veillonellaceae. Since pCS remains difficult to remove by dialysis, the gut microbiota could be a future target to decrease pCS levels and its toxicity, even at earlier stages of CKD, aiming at slowing down the progression of the disease and decreasing the cardiovascular burden.

  7. p-Cresyl Sulfate

    Science.gov (United States)

    Gryp, Tessa; Vanholder, Raymond; Vaneechoutte, Mario; Glorieux, Griet

    2017-01-01

    If chronic kidney disease (CKD) is associated with an impairment of kidney function, several uremic solutes are retained. Some of these exert toxic effects, which are called uremic toxins. p-Cresyl sulfate (pCS) is a prototype protein-bound uremic toxin to which many biological and biochemical (toxic) effects have been attributed. In addition, increased levels of pCS have been associated with worsening outcomes in CKD patients. pCS finds its origin in the intestine where gut bacteria metabolize aromatic amino acids, such as tyrosine and phenylalanine, leading to phenolic end products, of which pCS is one of the components. In this review we summarize the biological effects of pCS and its metabolic origin in the intestine. It appears that, according to in vitro studies, the intestinal bacteria generating phenolic compounds mainly belong to the families Bacteroidaceae, Bifidobacteriaceae, Clostridiaceae, Enterobacteriaceae, Enterococcaceae, Eubacteriaceae, Fusobacteriaceae, Lachnospiraceae, Lactobacillaceae, Porphyromonadaceae, Staphylococcaceae, Ruminococcaceae, and Veillonellaceae. Since pCS remains difficult to remove by dialysis, the gut microbiota could be a future target to decrease pCS levels and its toxicity, even at earlier stages of CKD, aiming at slowing down the progression of the disease and decreasing the cardiovascular burden. PMID:28146081

  8. Synthesis and structural characterization of PHP[(C(5)Me(4))(2)], a monodentate chiral phosphine derived from intramolecular C-C coupling of tetramethylcyclopentadienyl groups: an evaluation of steric and electronic properties.

    Science.gov (United States)

    Shin, J H; Bridgewater, B M; Churchill, D G; Parkin, G

    2001-10-22

    The chiral monodentate phosphine PhP[(C(5)Me(4))(2)] is readily obtained by oxidation of the lithium complex Li(2)[PhP(C(5)Me(4))(2)] with I(2), which couples the two cyclopentadienyl groups to form a five-membered heterocyclic ring. The steric and electronic properties of PhP[(C(5)Me(4))(2)] have been evaluated by X-ray diffraction and IR spectroscopic studies on a variety of derivatives, including Ph[(C(5)Me(4))(2)]PE (E = S, Se), Cp*MCl(4)[P[(C(5)Me(4))(2)]Ph] (M = Mo, Ta), Ir[P[(C(5)Me(4))(2)]Ph](2)(CO)Cl, and CpFe(CO)[PhP[(C(5)Me(4))(2)

  9. Sulfated tyrosines 27 and 29 in the N-terminus of human CXCR3 participate in binding native IP-10

    Institute of Scientific and Technical Information of China (English)

    Jinming GAO; Ruolan XIANG; Lei JIANG; Wenhui LI; Qiping FENG; Zijiang GUO; Qi SUN; Zhengpei ZENG; Fude FANG

    2009-01-01

    Aim:Human CXCR3,a seven-transmembrane segment (7TMS),is predominantly expressed in Th1-mediated responses.Interferon-γ-inducible protein 10 (IP-10) is an important ligand for CXCR3.Their interaction is pivotal for leukocyte migra-tion and activation.Tyrosine sulfation in 7TMS is a posttranslational modification that contributes substantially to ligand binding.We aimed to study the role of tyrosine sulfation of CXCR3 in the protein's binding to IP-10.Methods: Plasmids encoding CXCR3 and its mutants were prepared by PCR and site-directed mutagenesis.HEK 293T cells were transfected with plasmids encoding CXCR3 or its variants using calcium phosphate.Transfected cells were labeled with [35S]-cysteine and methionine or [35S]-Na2SO3 and then analyzed by immunoprecipitation to measure sulfation.Experi-ments with 125I-labeled IP-10 were carried out to evaluate the affinity of CXCR3 for its ligand.Calcium influx assays were used to measure intercellular signal transduction.Results: Our data show that sulfate moieties are added to tyrosines 27 and 29 of CXCR3.Mutation of these two tyrosines to phenylalanines substantially decreases binding of CXCR3 to IP-10 and appears to eliminate the associated signal transduc-tion.Tyrosine sulfation of CXCR3 is enhanced by tyrosyl protein sulfotransferases (TPSTs),and it is weakened by shRNA constructs.The binding ability of CXCR3 to IP-10 is increased by TPSTs and decreased by shRNAs.Conclusion: This study identifies two sulfated tyrosines in the N-terminus of CXCR3 as part of the binding site for IP-10,and it underscores the fact that tyrosine sulfation in the N-termini of 7TMS receptors is functionally important for ligand interactions.Our study suggests a molecular target for inhibiting this ligand-receptor interaction.

  10. 21 CFR 184.1307 - Ferric sulfate.

    Science.gov (United States)

    2010-04-01

    ... Substances Affirmed as GRAS § 184.1307 Ferric sulfate. (a) Ferric sulfate (iron (III) sulfate, Fe2(SO4)3 CAS Reg. No. 10028-22-5) is a yellow substance that may be prepared by oxidizing iron (II) sulfate or by treating ferric oxide or ferric hydroxide with sulfuric acid. (b) The ingredient must be of a...

  11. 21 CFR 558.364 - Neomycin sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate. 558.364 Section 558.364 Food and... in Animal Feeds § 558.364 Neomycin sulfate. (a) Approvals. Type A medicated article: 325 grams per.... (c) (d) Conditions of use. Neomycin sulfate is used as follows: Neomycin Sulfate...

  12. A density functional theory investigation of the interaction of the tetraaqua calcium cation with bidentate carbonyl ligands.

    Science.gov (United States)

    Quattrociocchi, Daniel Garcez S; Meuser, Marcos Vinicius Monsores; Ferreira, Glaucio Braga; de M Carneiro, José Walkimar; Stoyanov, Stanislav R; da Costa, Leonardo Moreira

    2017-02-01

    Calcium complexes with bidentate carbonyl ligands are important in biological systems, medicine and industry, where the concentration of Ca(2+) is controlled using chelating ligands. The exchange of two water molecules of [Ca(H2O)6](2+) for one bidentate monosubstituted and homo disubstituted dicarbonyl ligand was investigated using the B3LYP/6-311++G(d,p) method. The ligand substituents NH2, OCH3, OH, CH3, H, F, Cl, CN and NO2 are functional groups with distinct electron-donating and -withdrawing effects that bond directly to the sp(2) C atom of the carbonyl group. The geometry, charge and energy characteristics of the complexes were analyzed to help understand the effects of substituents, spacer length and chelation. Coordination strength was quantified in terms of the enthalpy and free energy of the exchange reaction. The most negative enthalpies were calculated for the coordination of bidentate ligands containing three to five methylene group spacers between carbonyls. The chelate effect contribution was analyzed based on the thermochemistry. The electronic character of the substituent modulates the strength of binding to the metal cation, as ligands containing electron-donor substituents coordinate stronger than those with electron-acceptor substituents. This is reflected in the geometric (bond length and chelating angle), electronic (atomic charges) and energetic (components of the total interacting energy) characteristics of the complexes. Energy decomposition analysis (EDA)-an approach for partitioning of the energy into its chemical origins-shows that the electrostatic component of the coordination is predominant, and yields relevant contribution of the covalent term, especially for the electron-withdrawing substituted ligands. The chelate effect of the bidentate ligands was noticeable when compared with substitution by two monodentate ligands. Graphical abstract The affinity of 18 bidentate carbonyl ligands toward the [Ca(H2O)4](2+) cation is evaluated in

  13. Glycine zinc sulfate pentahydrate: redetermination at 10 K from time-of-flight neutron Laue diffraction

    Directory of Open Access Journals (Sweden)

    A. Dominic Fortes

    2016-10-01

    Full Text Available Single crystals of glycine zinc sulfate pentahydrate [systematic name: hexaaquazinc tetraaquadiglycinezinc bis(sulfate], [Zn(H2O6][Zn(C2H5NO22(H2O4](SO42, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octahedra on sites of symmetry -1 and two SO4 tetrahedra with site symmetry 1; the octahedra comprise one [tetraaqua-diglycine zinc]2+ ion (centred on one Zn atom and one [hexaaquazinc]2+ ion (centred on the other Zn atom; the glycine zwitterion, NH3+CH2COO−, adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N—H...O hydrogen bonds between the amine and carboxylate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and Uij parameters, which provide accurate internuclear X—H (X = N, O bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework.

  14. Mechanisms of Chromate, Selenate, and Sulfate Adsorption on Al-Substituted Ferrihydrite: Implications for Ferrihydrite Surface Structure and Reactivity.

    Science.gov (United States)

    Johnston, Chad P; Chrysochoou, Maria

    2016-04-05

    Ferrihydrite is a nanocrystalline Fe (hydr)oxide and important sink for environmental contaminants. Although Fe (hydr)oxides are rarely pure in natural systems, little is known about the effects of structural impurities such as Al on the surface properties and reactivity of ferrihydrite. In this study, we characterized the adsorption mechanisms of chromate, selenate, and sulfate on Al-substituted ferrihydrite (0, 6, 12, 18, and 24 mol % Al) using in situ attenuated total reflection Fourier transform infrared spectroscopy. Spectral data sets recorded as a function of pH were processed using a multivariate curve resolution technique to identify which types of surface species form and to generate their concentration profiles as a function of pH and Al content. Results show a significant increase in relative fraction of outer-sphere complexes for all three oxyanions with increasing Al substitution. In addition, the effect of Al substitution is found to be mechanism-specific in the case of chromate, with bidentate complexes disproportionately suppressed over monodentate complexes at higher Al contents. Overall, our findings have important implications for the fate of chromate, selenate, and sulfate in subsurface environments and offer new insight into the surface reactivity of Al-ferrihydrite.

  15. Ligand modeling and design

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B.P. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    The purpose of this work is to develop and implement a molecular design basis for selecting organic ligands that would be used in the cost-effective removal of specific radionuclides from nuclear waste streams. Organic ligands with metal ion specificity are critical components in the development of solvent extraction and ion exchange processes that are highly selective for targeted radionuclides. The traditional approach to the development of such ligands involves lengthy programs of organic synthesis and testing, which in the absence of reliable methods for screening compounds before synthesis, results in wasted research effort. The author`s approach breaks down and simplifies this costly process with the aid of computer-based molecular modeling techniques. Commercial software for organic molecular modeling is being configured to examine the interactions between organic ligands and metal ions, yielding an inexpensive, commercially or readily available computational tool that can be used to predict the structures and energies of ligand-metal complexes. Users will be able to correlate the large body of existing experimental data on structure, solution binding affinity, and metal ion selectivity to develop structural design criteria. These criteria will provide a basis for selecting ligands that can be implemented in separations technologies through collaboration with other DOE national laboratories and private industry. The initial focus will be to select ether-based ligands that can be applied to the recovery and concentration of the alkali and alkaline earth metal ions including cesium, strontium, and radium.

  16. Investigation of antitumor potential of Ni(II) complexes with tridentate PNO acylhydrazones of 2-(diphenylphosphino)benzaldehyde and monodentate pseudohalides.

    Science.gov (United States)

    Čobeljić, Božidar; Milenković, Milica; Pevec, Andrej; Turel, Iztok; Vujčić, Miroslava; Janović, Barbara; Gligorijević, Nevenka; Sladić, Dušan; Radulović, Siniša; Jovanović, Katarina; Anđelković, Katarina

    2016-04-01

    Square-planar azido Ni(II) complex with condensation product of 2-(diphenylphosphino)benzaldehyde and Girard's T reagent was synthesized and its crystal structure was determined. Cytotoxic activity of the azido complex and previously synthesized isothiocyanato, cyanato and chlorido Ni(II) complexes with this ligand was examined on six tumor cell lines (HeLa, A549, K562, MDA-MB-453, MDA-MB-361 and LS-174) and two normal cell line (MRC-5 and BEAS-2B). All the investigated nickel(II) complexes were cytotoxic against all tumor cell lines. The newly synthesized azido complex showed selectivity to HeLa and A549 tumor cell lines compared to the normal cells (for A549 IC50 was similar to that of cisplatin). Azido complex interferes with cell cycle phase distribution of A549 and HeLa cells and possesses nuclease activity towards supercoiled DNA. The observed selectivity of the azido complex for some tumor cell lines can be connected with its strong DNA damaging activity.

  17. Ligand modeling and design

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B. [Pacific Northwest Lab., Richland, WA (United States)

    1996-10-01

    The purpose of this work is to develop and implement a molecular design basis for selecting organic ligands that would be used tin applications for the cost-effective removal of specific radionuclides from nuclear waste streams.

  18. Bioengineered heparins and heparan sulfates.

    Science.gov (United States)

    Fu, Li; Suflita, Matthew; Linhardt, Robert J

    2016-02-01

    Heparin and heparan sulfates are closely related linear anionic polysaccharides, called glycosaminoglycans, which exhibit a number of important biological and pharmacological activities. These polysaccharides, having complex structures and polydispersity, are biosynthesized in the Golgi of animal cells. While heparan sulfate is a widely distributed membrane and extracellular glycosaminoglycan, heparin is found primarily intracellularly in the granules of mast cells. While heparin has historically received most of the scientific attention for its anticoagulant activity, interest has steadily grown in the multi-faceted role heparan sulfate plays in normal and pathophysiology. The chemical synthesis of these glycosaminoglycans is largely precluded by their structural complexity. Today, we depend on livestock animal tissues for the isolation and the annual commercial production of hundred ton quantities of heparin used in the manufacture of anticoagulant drugs and medical device coatings. The variability of animal-sourced heparin and heparan sulfates, their inherent impurities, the limited availability of source tissues, the poor control of these source materials and their manufacturing processes, suggest a need for new approaches for their production. Over the past decade there have been major efforts in the biotechnological production of these glycosaminoglycans, driven by both therapeutic applications and as probes to study their natural functions. This review focuses on the complex biology of these glycosaminoglycans in human health and disease, and the use of recombinant technology in the chemoenzymatic synthesis and metabolic engineering of heparin and heparan sulfates. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. SOME SULFATO ADDUCTS AND DERIVATIVE: SYNTHESIS AND SPECTROSCOPIC STUDY

    Directory of Open Access Journals (Sweden)

    MOUHAMADOU BIRAME DIOP

    2014-11-01

    Full Text Available Three new adducts and derivative have been synthesized and studied by infrared and NMR spectroscopies. The suggested structures are discrete with a sulfate behaving as a monochelating, bichelating or monodentate ligand, the environments around the tin centre being octahedral or pentagonal bipyramidal. In all the studied compounds, proposed supramolecular architectures may be obtained when intermolecular hydrogen bonds are considered.

  20. Heparan sulfate structure: methods to study N-sulfation and NDST action.

    Science.gov (United States)

    Dagälv, Anders; Lundequist, Anders; Filipek-Górniok, Beata; Dierker, Tabea; Eriksson, Inger; Kjellén, Lena

    2015-01-01

    Heparan sulfate proteoglycans are important modulators of cellular processes where the negatively charged polysaccharide chains interact with target proteins. The sulfation pattern of the heparan sulfate chains will determine the proteins that will bind and the affinity of the interactions. The N-deacetylase/N-sulfotransferase (NDST) enzymes are of key importance during heparan sulfate biosynthesis when the sulfation pattern is determined. In this chapter, metabolic labeling of heparan sulfate with [(35)S]sulfate or [(3)H]glucosamine in cell cultures is described, in addition to characterization of polysaccharide chain length and degree of N-sulfation. Methods to measure NDST enzyme activity are also presented.

  1. Hexacoordinate Silicon Compounds with a Dianionic Tetradentate (N,N′,N′,N-Chelating Ligand

    Directory of Open Access Journals (Sweden)

    Daniela Gerlach

    2016-04-01

    Full Text Available In the context of our systematic investigations of penta- and hexacoordinate silicon compounds, which included dianionic tri- (O,N,O′; O,N,N′ and tetradentate (O,N,N,O; O,N,N′,O′ chelators, we have now explored silicon coordination chemistry with a dianionic tetradentate (N,N′,N′,N chelator. The ligand [o-phenylene-bis(pyrrole-2-carbaldimine, H2L] was obtained by condensation of o-phenylenediamine and pyrrole-2-carbaldehyde and subsequently silylated with chlorotrimethylsilane/triethylamine. Transsilylation of this ligand precursor (Me3Si2L with chlorosilanes SiCl4, PhSiCl3, Ph2SiCl2, (Anis2SiCl2 and (4-Me2N-C6H4PhSiCl2 afforded the hexacoordinate Si complexes LSiCl2, LSiPhCl, LSiPh2, LSi(Anis2 and LSiPh(4-Me2N-C6H4, respectively (Anis = anisyl = 4-methoxyphenyl. 29Si NMR spectroscopy and, for LSiPh2, LSi(Anis2 and LSiPh(4-Me2N-C6H4, single-crystal X-ray diffraction confirm hexacoordination of the Si atoms. The molecular structures of LSiCl2 and LSiPhCl were elucidated by computational methods. Despite the two different N donor sites (pyrrole N, X-type donor; imine N, L-type donor, charge delocalization within the ligand backbone results in compounds with four similar Si–N bonds. Charge distribution within the whole molecules was analyzed by calculating the Natural Charges (NCs. Although these five compounds carry electronically different monodentate substituents, their constituents reveal rather narrow ranges of their charges (Si atoms: +2.10–+2.22; monodentate substituents: −0.54–−0.56; L2−: −1.02–−1.11.

  2. Studies on Sulfation of Lycium barbarum Polysaccharides

    Institute of Scientific and Technical Information of China (English)

    YI,Jian-Ping; YAN,Hong; ZHONG,Ru-Gang

    2004-01-01

    @@ Polysaccharides can anti-virus, such as human immunodeficiency virus (HIV-1),[1] herpes simplex virus (HSV-1,HSV-2) and cytomegalovirus. Some of them are sulfates, e.g. dextran sulfate, heparin, sulfonation of chitosan and sulfated derivatives of Lentinan. Our results showed that sulfated derivatives of Lycium barbarum polysaccharides (LBP)have anti-HIV activity. Because the anti-HIV activity of LBP was deeply dependent on the molecular weight, the sulfation pattern and glycosidic branches besides degree of sulfation (DS), so we emphasized our work on the factors of DS.

  3. Sulfate reduction in freshwater peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Oequist, M.

    1996-12-31

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO{sub 4}{sup 2-} concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 {mu}M. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 {mu}M h{sup -1} while in B and C they were 1 and 0.05 {mu}M h{sup -1}, respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 {mu}g d{sup -1} g{sup -1}) were found 10 cm below the water table, in B (ca. 1.0 {mu}g d{sup -1} g{sup -1}) in the vicinity of the water table, and in C (0.75 {mu}g d{sup -1} g{sup -1}) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m{sup -2} d{sup -1}, while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m{sup -2} d{sup -1}, respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination

  4. Computational analysis of human N-acetylgalactosamine-6-sulfate sulfatase enzyme: an update in genotype-phenotype correlation for Morquio A.

    Science.gov (United States)

    Olarte-Avellaneda, Sergio; Rodríguez-López, Alexander; Alméciga-Díaz, Carlos Javier; Barrera, Luis Alejandro

    2014-11-01

    Mucopolysaccharidosis IV A (MPS IV A) is a lysosomal storage disease produced by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme. Although genotype-phenotype correlations have been reported, these approaches have not enabled to establish a complete genotype-phenotype correlation, and they have not considered a ligand-enzyme interaction. In this study, we expanded the in silico evaluation of GALNS mutations by using several bioinformatics tools. Tertiary GALNS structure was modeled and used for molecular docking against galactose-6-sulfate, N-acetylgalactosamine-6-sulfate, keratan sulfate, chondroitin-6-sulfate, and the artificial substrate 4-methylumbelliferyl-β-D-galactopyranoside-6-sulfate. Furthermore, we considered the evolutionary residue conservation, change conservativeness, position within GALNS structure, and the impact of amino acid substitution on the structure and function of GALNS. Molecular docking showed that amino acids involved in ligand interaction correlated with those observed in other human sulfatases, and mutations within the active cavity reduced affinity of all evaluated ligands. Combination of several bioinformatics approaches allowed to explaine 90% of the missense mutations affecting GALNS, and the prediction of the phenotype for another 21 missense mutations. In summary, we have shown for the first time a docking evaluation of natural and artificial ligands for human GALNS, and proposed an update in genotype-phenotype correlation for Morquio A, based on the use of multiple parameters to predict the disease severity.

  5. Influence of functionalized pyridine ligands on the radio/chemical behavior of [M(I)(CO)3](+) (M = Re and (99m)Tc) 2 + 1 complexes.

    Science.gov (United States)

    Hayes, Thomas R; Lyon, Patrice A; Barnes, Charles L; Trabue, Steven; Benny, Paul D

    2015-02-16

    While a number of chelate strategies have been developed for the organometallic precursor fac-[M(I)(OH2)3(CO)3](+) (M = Re, (99m)Tc), a unique challenge has been to improve the overall function and performance of these complexes for in vivo and in vitro applications. Since its discovery, fac-[M(I)(OH2)3(CO)3](+) has served as an essential scaffold for the development of new targeted (99m)Tc based radiopharmaceuticals due to its labile aquo ligands. However, the lipophilic nature of the fac-[M(I)(CO)3](+) core can influence the in vivo pharmacokinetics and biodistribution of the complexes. In an effort to understand and improve this behavior, monosubstituted pyridine ligands were used to assess the impact of donor nitrogen basicity on binding strength and stability of fac-[M(I)(CO)3](+) in a 2 + 1 labeling strategy. A series of Re and (99m)Tc complexes were synthesized with picolinic acid as a bidentate ligand and 4-substituted pyridine ligands. These complexes were designed to probe the effect of pKa from the monodentate pyridine ligand both at the macro scale and radiochemical concentrations. Comparison of X-ray structural data and radiochemical solution experiments clearly indicate an increase in overall yield and stability as pyridine basicity increased.

  6. A sulfate conundrum: Dissolved sulfates of deep-saline brines and carbonate-associated sulfates

    Science.gov (United States)

    Labotka, Dana M.; Panno, Samuel V.; Locke, Randall A.

    2016-10-01

    Sulfates in deeply circulating brines and carbonate-associated sulfates (CAS) within sedimentary units of the Cambrian strata in the Illinois Basin record a complex history. Dissolved sulfate within the Mt. Simon Sandstone brines exhibits average δ34SSO4 values of 35.4‰ and δ18OSO4 values of 14.6‰ and appears to be related to Cambrian seawater sulfate, either original seawater or sourced from evaporite deposits such as those in the Michigan Basin. Theoretical and empirical relationships based on stable oxygen isotope fractionation suggest that sulfate within the lower depths of the Mt. Simon brines has experienced a long period of isolation, possibly several tens of millions of years. Comparison with brines from other stratigraphic units shows the Mt. Simon brines are geochemically unique. Dissolved sulfate from brines within the Ironton-Galesville Sandstone averages 22.7‰ for δ34SSO4 values and 13.0‰ for δ18OSO4 values. The Ironton-Galesville brine has mixed with younger groundwater, possibly of Ordovician to Devonian age and younger. The Eau Claire Formation lies between the Mt. Simon and Ironton-Galesville Sandstones. The carbonate units of the Eau Claire and stratigraphically equivalent Bonneterre Formation contain CAS that appears isotopically related to the Late Pennsylvanian-Early Permian Mississippi Valley-type ore pulses that deposited large sulfide minerals in the Viburnum Trend/Old Lead Belt ore districts. The δ34SCAS values range from 21.3‰ to 9.3‰, and δ18OCAS values range from +1.4‰ to -2.6‰ and show a strong covariance (R2 = 0.94). The largely wholesale replacement of Cambrian seawater sulfate signatures in these dolomites does not appear to have affected the sulfate signatures in the Mt. Simon brines even though these sulfide deposits are found in the stratigraphically equivalent Lamotte Sandstone to the southwest. On the basis of this and previous studies, greater fluid densities of the Mt. Simon brines may have prevented the

  7. Sulfate transport in toad skin

    DEFF Research Database (Denmark)

    Larsen, Erik Hviid; Simonsen, K

    1988-01-01

    1. In short-circuited toad skin preparations exposed bilaterally to NaCl-Ringer's containing 1 mM SO2(-4), influx of sulfate was larger than efflux showing that the skin is capable of transporting sulfate actively in an inward direction. 2. This active transport was not abolished by substituting...... apical Na+ for K+. 3. Following voltage activation of the passive Cl- permeability of the mitochondria-rich (m.r.) cells sulfate flux-ratio increased to a value predicted from the Ussing flux-ratio equation for a monovalent anion. 4. In such skins, which were shown to exhibit vanishingly small leakage...... conductances, the variation of the rate coefficient for sulfate influx (y) was positively correlated with the rate coefficient for Cl- influx (x), y = 0.035 x - 0.0077 cm/sec (r = 0.9935, n = 15). 5. Addition of the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine to the serosal bath of short...

  8. Sulfation of thyroid hormone by estrogen sulfotransferase

    NARCIS (Netherlands)

    M.H.A. Kester (Monique); T.J. Visser (Theo); C.H. van Dijk (Caren); D. Tibboel (Dick); A.M. Hood (Margaret); N.J. Rose; W. Meinl; U. Pabel; H. Glatt; C.N. Falany; M.W. Coughtrie

    1999-01-01

    textabstractSulfation is one of the pathways by which thyroid hormone is inactivated. Iodothyronine sulfate concentrations are very high in human fetal blood and amniotic fluid, suggesting important production of these conjugates in utero. Human estrogen sulfotransferas

  9. Sulfation of thyroid hormone by estrogen sulfotransferase

    NARCIS (Netherlands)

    M.H.A. Kester (Monique); T.J. Visser (Theo); C.H. van Dijk (Caren); D. Tibboel (Dick); A.M. Hood (Margaret); N.J. Rose; W. Meinl; U. Pabel; H. Glatt; C.N. Falany; M.W. Coughtrie

    1999-01-01

    textabstractSulfation is one of the pathways by which thyroid hormone is inactivated. Iodothyronine sulfate concentrations are very high in human fetal blood and amniotic fluid, suggesting important production of these conjugates in utero. Human estrogen sulfotransferas

  10. Sulfation of thyroid hormone by estrogen sulfotransferase

    NARCIS (Netherlands)

    M.H.A. Kester (Monique); T.J. Visser (Theo); C.H. van Dijk (Caren); D. Tibboel (Dick); A.M. Hood (Margaret); N.J. Rose; W. Meinl; U. Pabel; H. Glatt; C.N. Falany; M.W. Coughtrie

    1999-01-01

    textabstractSulfation is one of the pathways by which thyroid hormone is inactivated. Iodothyronine sulfate concentrations are very high in human fetal blood and amniotic fluid, suggesting important production of these conjugates in utero. Human estrogen

  11. Photochemistry of RuII 4,4′-Bi-1,2,3-triazolyl (btz) Complexes: Crystallographic Characterization of the Photoreactive Ligand-Loss Intermediate trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+

    Science.gov (United States)

    Welby, Christine E; Armitage, Georgina K; Bartley, Harry; Wilkinson, Aaron; Sinopoli, Alessandro; Uppal, Baljinder S; Rice, Craig R; Elliott, Paul I P

    2014-01-01

    We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+ (1 a) that contains a monodentate chelate ligand. This and analogous complexes can be observed during the photolysis reactions of a family of complexes of the form [Ru()(btz)2]2+ (1 a–d: btz=1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl; =a) 2,2′-bipyridyl (bpy), b) 4,4′-dimethyl-2,2′-bipyridyl (dmbpy), c) 4,4′-dimethoxy-2,2′-bipyridyl (dmeobpy), d) 1,10-phenanthroline (phen)). In acetonitrile solutions, 1 a–d eventually convert to the bis-solvento complexes trans-[Ru()(btz)(NCMe)2]2+ (3 a–d) along with one equivalent of free btz, in a process in which the remaining coordinated bidentate ligands undergo a new rearrangement such that they become coplanar. X-ray crystal structure of 3 a and 3 d confirmed the co-planar arrangement of the and btz ligands and the trans coordination of two solvent molecules. These conversions proceed via the observed intermediate complexes 2 a–d, which are formed quantitatively from 1 a–d in a matter of minutes and to which they slowly revert back on being left to stand in the dark over several days. The remarkably long lifetime of the intermediate complexes (>12 h at 40 °C) allowed the isolation of 2 a in the solid state, and the complex to be crystallographically characterized. Similarly to the structures adopted by complexes 3 a and d, the bpy and κ2-btz ligands in 2 a coordinate in a square-planar fashion with the second monodentate btz ligand coordinated trans to an acetonitrile ligand. PMID:24889966

  12. Sulfate-rich Archean Oceans

    Science.gov (United States)

    Brainard, J. L.; Choney, A. P.; Ohmoto, H.

    2012-12-01

    There is a widely held belief that prior to 2.4 Ga, the Archean oceans and atmosphere were reducing, and therefore sulfate poor (concentrations 100 m), widely distributed (> km2), and contain only minor amounts of sulfides. These barite beds may have developed from reactions between Ba-rich hydrothermal fluids and evaporate bodies. Simple mass balance calculations suggest that the sulfate contents of the pre-evaporitic seawater must have been greater than ~1 mM. Some researchers have suggested that the SO4 for these beds was derived from the hydrolysis of SO2-rich magmatic fluids. However, this was unlikely as the reaction, 4SO2 + 4H2O → 3H2SO4 + H2S would have produced large amounts of sulfide, as well as sulfate minerals. Many Archean-aged volcanogenic massive sulfide (VMS) deposits, much like those of the younger ages, record evidence for abundant seawater sulfate. As VMS deposits are most likely formed by submarine hydrothermal fluids that developed from seawater circulating through the seafloor rock, much of the seawater sulfate is reduced to from sulfides at depths. However, some residual sulfate in the hydrothermal fluids, with or without the addition of sulfate from the local seawater, can form sulfate minerals such as barite at near the seafloor. The d34S relationships between barites and pyrites in the Archean VMS deposits are similar to those of the younger VMS deposits, except for the lower d34S values for the seawater SO4. The abundance of pyrite in Archean black shales is also evidence of sulfate rich seawater. Pyrites in Archean-aged black shales were most likely the products of either bacterial or thermochemical sulfate reduction during diagenesis of the sediments. Their abundance in sedimentary rocks is determined by: (a) the availability of reactive carbon; (b) the availability of reactive Fe (Fe3+ hydroxides and Fe2+-rich pore fluid); (c) the sedimentation rate; and (d) the flux of SO42- in the sediments, which depends on the seawater SO42

  13. 2-Acylpyrroles as mono-anionic O,N-chelating ligands in silicon coordination chemistry.

    Science.gov (United States)

    Kämpfe, Alexander; Brendler, Erica; Kroke, Edwin; Wagler, Jörg

    2014-07-21

    Kryptopyrrole (2,4-dimethyl-3-ethylpyrrole) was acylated with, for example, benzoyl chloride to afford 2-benzoyl-3,5-dimethyl-4-ethylpyrrole (L(1)H). With SiCl4 this ligand reacts under liberation of HCl and formation of the complex L(1)2SiCl2. In related reactions with HSiCl3 or H2SiCl2, the same chlorosilicon complex is formed under liberation of HCl and H2 or liberation of H2, respectively. The chlorine atoms of L(1)2SiCl2 can be replaced by fluoride and triflate using ZnF2 and Me3Si-OTf, respectively. The use of a supporting base (triethylamine) is required for the complexation of phenyltrichlorosilane and diphenyldichlorosilane. The complexes L(1)2SiCl2, L(1)2SiF2, L(1)2Si(OTf)2, L(1)2SiPhCl, and L(1)2SiPh2 exhibit various configurations of the octahedral silicon coordination spheres (i.e. cis or trans configuration of the monodentate substituents, different orientations of the bidentate chelating ligands relative to each other). Furthermore, cationic silicon complexes L(1)3Si(+) and L(1) SiPh(+) were synthesized by chloride abstraction with GaCl3. In contrast, reaction of L(1)2SiCl2 with a third equivalent of L(1)H in the presence of excess triethylamine produced a charge-neutral hexacoordinate Si complex with a new tetradentate chelating ligand which formed by Si-templated C-C coupling of two ligands L(1).

  14. Syntheses and Structures of Two Mixed Ligands Lanthanide Complexes with N,N'-Substituted Adipamide

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Crystal structures of neodymium (Ⅲ) and dysprosium (Ⅲ) nitrate complexes with the new ligand N, N'-dimethyl-N, N'-diphenyladipamide (mpaa) has been determined. Both complexes are triclinic with space group Pi ,formula [C22H30N5NdO12S]2 1 [C42H54N7DyO14S 2]Mr = 1465.62[1075.48], a = 8.541(1)[9.711(2)], b = 11.915(1)[16.017(3)], c = 15.906(1)[16.686(3)] A,α =107.22(1)[109.600(1)],β = 98.12(1)[92.50(1)], γ = 99.78(1) [96.22(1)]° ,μ=0.71073cn-1; R=0.0261 [0.0364], wR=0.0611 [0.0857] reflections with I>2 σ (Ⅰ). Complex (1)is dinuclear, in which two Nd(Ⅲ) ions are double-bridged by two mpaa ligands. And Dy(mpaa)2(dmso)(NO3)3 (2) (dmso= dimethylsulfoxide) is a mononuclear complex, in which one of the two C=O groups in MPAA is uncoordinated. In the two above complexes, each Ln(Ⅲ)ion is nine-coordinated including three bidenate nitrates, one dmso molecule and two carbonyl oxygens from two different mpaa ligands. Neutral monodentate dmso enters the coordination in diamides of the type (R1R2NCO)2(CH2)n was increased, the ligand prefers to act as a bridging reagent rather than a chelate.

  15. Berberine Sulfate Attenuates Osteoclast Differentiation through RANKL Induced NF-κB and NFAT Pathways.

    Science.gov (United States)

    Zhou, Lin; Song, Fangming; Liu, Qian; Yang, Mingli; Zhao, Jinmin; Tan, Renxiang; Xu, Jun; Zhang, Ge; Quinn, Julian M W; Tickner, Jennifer; Xu, Jiake

    2015-11-13

    Osteoporosis, a metabolic bone disease, is characterized by an excessive formation and activation of osteoclasts. Anti-catabolic treatment using natural compounds has been proposed as a potential therapeutic strategy against the osteoclast related osteolytic diseases. In this study, the activity of berberine sulfate (an orally available form of berberine) on osteoclast differentiation and its underlying molecular mechanisms of action were investigated. Using bone marrow macrophages (BMMs) derived osteoclast culture system, we showed that berberine sulfate at the dose of 0.25, 0.5 and 1 μM significantly inhibited the formation of osteoclasts. Notably, berberine sulfate at these doses did not affect the BMM viability. In addition, we observed that berberine sulfate inhibited the expression of osteoclast marker genes, including cathepsin K (Ctsk), nuclear factor of activated T cells cytoplasmic 1 (NFATc1), tartrate resistant acid phosphatase (TRAcP, Acp5) and Vacuolar-type H+-ATPase V0 subunit D2 (V-ATPase d2). Luciferase reporter gene assay and Western blot analysis further revealed that berberine sulfate inhibits receptor for activation of nuclear factor ligand (RANKL)-induced NF-κB and NFAT activity. Taken together, our results suggest that berberine sulfate is a natural compound potentially useful for the treatment of osteoporosis.

  16. 21 CFR 524.1484e - Neomycin sulfate and polymyxin B sulfate ophthalmic solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate and polymyxin B sulfate ophthalmic solution. 524.1484e Section 524.1484e Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... DOSAGE FORM NEW ANIMAL DRUGS § 524.1484e Neomycin sulfate and polymyxin B sulfate ophthalmic solution....

  17. 21 CFR 582.1643 - Potassium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium sulfate. 582.1643 Section 582.1643 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1643 Potassium sulfate. (a) Product. Potassium sulfate. (b) Conditions of use....

  18. 21 CFR 184.1643 - Potassium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium sulfate. 184.1643 Section 184.1643 Food... Specific Substances Affirmed as GRAS § 184.1643 Potassium sulfate. (a) Potassium sulfate (K2SO4, CAS Reg... having a bitter, saline taste. It is prepared by the neutralization of sulfuric acid with...

  19. 21 CFR 582.5443 - Magnesium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium sulfate. 582.5443 Section 582.5443 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5443 Magnesium sulfate. (a) Product. Magnesium sulfate. (b) Conditions of use....

  20. 21 CFR 184.1443 - Magnesium sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium sulfate. 184.1443 Section 184.1443 Food... Specific Substances Affirmed as GRAS § 184.1443 Magnesium sulfate. (a) Magnesium sulfate (MgSO4·7H2O, CAS... magnesium oxide, hydroxide, or carbonate with sulfuric acid and evaporating the solution to...

  1. Sulfate transport in Penicillium chrysogenum plasma membranes.

    OpenAIRE

    Hillenga, Dirk J.; Versantvoort, Hanneke J.M.; Driessen, Arnold J. M.; Konings, Wil N.

    1996-01-01

    Transport studies with Penicillium chrysogenum plasma membranes fused with cytochrome c oxidase liposomes demonstrate that sulfate uptake is driven by the transmembrane pH gradient and not by the transmembrane electrical potential. Ca2+ and other divalent cations are not required. It is concluded that the sulfate transport system catalyzes the symport of two protons with one sulfate anion.

  2. Sulfate-reducing prokaryotes in river floodplains

    NARCIS (Netherlands)

    Miletto, M.

    2007-01-01

    This thesis constitutes a pioneer attempt at elucidating the ecology of sulfate-reducing prokaryotes in river floodplains. These are non-typical sulfate-reducing environmental settings, given the generally low sulfate concentration that characterize freshwater habitats, and river flow regulation

  3. 21 CFR 582.5315 - Ferrous sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ferrous sulfate. 582.5315 Section 582.5315 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5315 Ferrous sulfate. (a) Product. Ferrous sulfate. (b) Conditions of use. This substance...

  4. 21 CFR 582.5461 - Manganese sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Manganese sulfate. 582.5461 Section 582.5461 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Supplements 1 § 582.5461 Manganese sulfate. (a) Product. Manganese sulfate. (b) Conditions of use....

  5. 21 CFR 184.1461 - Manganese sulfate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Manganese sulfate. 184.1461 Section 184.1461 Food... Specific Substances Affirmed as GRAS § 184.1461 Manganese sulfate. (a) Manganese sulfate (MnSO4·H2O, CAS... manganese compounds with sulfuric acid. It is also obtained as a byproduct in the manufacture...

  6. Combinatorial expression patterns of heparan sulfate sulfotransferases in zebrafish: III. 2-O-sulfotransferase and C5-epimerases.

    Science.gov (United States)

    Cadwallader, Adam B; Yost, H Joseph

    2007-02-01

    Heparan sulfate (HS) is an unbranched chain of repetitive disaccharides, which specifically binds ligands when attached to the cell surface or secreted extracellularly. HS chains contain sulfated domains, termed the HS fine structure, which give HS specific binding affinities for extracellular ligands. HS 2-O-sulfotransferase (2-OST) catalyzes the transfer of sulfate groups to the 2-O position of uronic acid residues of HS. We report here the characterization and developmental expression patterns of 2-OST in several tissues/organs throughout early zebrafish development, including early cleavage stages, eyes, somites, brain, internal organ primordial, and pectoral fin. The 2-OST gene has spatially and temporally distinct expression, which is a surprise given the essential role of 2-OST in HS fine structure formation. Furthermore, although 2-OST and C5-epimerase are predicted to be interdependent for protein translocation from the endoplasmic reticulum to the Golgi, their expression is not coordinately regulated during zebrafish development.

  7. Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

    Directory of Open Access Journals (Sweden)

    Juliana L. Dreyfuss

    2009-09-01

    Full Text Available Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.Proteoglicanos de heparam sulfato são encontrados tanto superfície celular quanto na matriz extracelular em todas as espécies animais. Esta revisão tem enfoque nas características estruturais dos proteoglicanos de heparam sulfato e nas interações destes proteoglicanos com proteínas que levam à sinalização celular. As cadeias de heparam sulfato, devido a sua variedade estrutural, são capazes de se ligar e interagir com ampla gama de proteínas, como fatores de crescimento, quimiocinas, morfógenos, componentes da matriz extracelular, enzimas, entreoutros. Existe uma especificidade estrutural que direciona as interações dos heparam sulfatos e proteínas alvo. Esta especificidade está relacionada com a estrutura da cadeia do polissacarídeo e os motivos conservados da cadeia polipeptídica das proteínas envolvidas nesta interação. Os heparam

  8. Ligand fitting with CCP4

    Science.gov (United States)

    2017-01-01

    Crystal structures of protein–ligand complexes are often used to infer biology and inform structure-based drug discovery. Hence, it is important to build accurate, reliable models of ligands that give confidence in the interpretation of the respective protein–ligand complex. This paper discusses key stages in the ligand-fitting process, including ligand binding-site identification, ligand description and conformer generation, ligand fitting, refinement and subsequent validation. The CCP4 suite contains a number of software tools that facilitate this task: AceDRG for the creation of ligand descriptions and conformers, Lidia and JLigand for two-dimensional and three-dimensional ligand editing and visual analysis, Coot for density interpretation, ligand fitting, analysis and validation, and REFMAC5 for macromolecular refinement. In addition to recent advancements in automatic carbohydrate building in Coot (LO/Carb) and ligand-validation tools (FLEV), the release of the CCP4i2 GUI provides an integrated solution that streamlines the ligand-fitting workflow, seamlessly passing results from one program to the next. The ligand-fitting process is illustrated using instructive practical examples, including problematic cases such as post-translational modifications, highlighting the need for careful analysis and rigorous validation. PMID:28177312

  9. Extracellular modulation of Fibroblast Growth Factor signaling through heparan sulfate proteoglycans in mammalian development.

    Science.gov (United States)

    Matsuo, Isao; Kimura-Yoshida, Chiharu

    2013-08-01

    Fibroblast Growth Factor (FGF) signaling plays crucial roles in multiple cellular processes including cell proliferation, differentiation, survival, and migration during mammalian embryogenesis. In the extracellular matrix, as well as at the cell surface, the movement of FGF ligands to target cells and the subsequent complex formations with their receptors are positively and negatively controlled extracellularly by heparan sulfate proteoglycans (HSPGs) such as syndecans, glypicans, and perlecan. Additionally, spreading of HSPGs by cleavage with sheddases such as proteinases and heparanases, and the overall length and sulfation level of specific heparan sulfate structures further generate a great diversity of FGF signaling outcomes. This review presents our current understanding of the regulatory mechanisms of FGF signaling in extracellular spaces through HSPGs in mammalian development.

  10. Heparan sulfate proteoglycans on the cell surface: versatile coordinators of cellular functions

    DEFF Research Database (Denmark)

    Tumova, S; Woods, A; Couchman, J R

    2000-01-01

    Heparan sulfate proteoglycans are complex molecules composed of a core protein with covalently attached glycosaminoglycan chains. While the protein part determines localization of the proteoglycan on the cell surfaces or in the extracellular matrix, the glycosaminoglycan component, heparan sulfate......, mediates interactions with a variety of extracellular ligands such as growth factors and adhesion molecules. Through these interactions, heparan sulfate proteoglycans participate in many events during cell adhesion, migration, proliferation and differentiation. We are determining the multitude...... of proteoglycan functions, as their intricate roles in many pathways are revealed. They act as coreceptors for growth factors, participate in signalling during cell adhesion, modulate the activity of a broad range of molecules, and partake in many developmental and pathological processes, including tumorigenesis...

  11. Tris(ethylenediaminecobalt(II sulfate

    Directory of Open Access Journals (Sweden)

    Bunlawee Yotnoi

    2010-06-01

    Full Text Available The structure of the title compound, [CoII(C2H8N23]SO4, the cobalt example of [M(C2H8N23]SO4, is reported. The Co and S atoms are located at the 2d and 2c Wyckoff sites (point symmetry 32, respectively. The Co atom is coordinated by six N atoms of three chelating ethylenediamine molecules generated from half of the ethylenediamine molecule in the asymmetric unit. The O atoms of the sulfate anion are disordered mostly over two crystallographic sites. The third disorder site of O (site symmetry 3 has a site occupancy approaching zero. The H atoms of the ethylenediamine molecules interact with the sulfate anions via intermolecular N—H...O hydrogen-bonding interactions.

  12. Sulfates on Mars: Indicators of Aqueous Processes

    Science.gov (United States)

    Bishop, Janice L.; Lane, Melissa D.; Dyar, M. Darby; Brown, Adrian J.

    2006-01-01

    Recent analyses by MER instruments at Meridiani Planum and Gusev crater and the OMEGA instrument on Mars Express have provided detailed information about the presence of sulfates on Mars [1,2,3]. We are evaluating these recent data in an integrated multi-disciplinary study of visible-near-infrared, mid-IR and Mossbauer spectra of several sulfate minerals and sulfate-rich analog sites. Our analyses suggest that hydrated iron sulfates may account for features observed in Mossbauer and mid-IR spectra of Martian soils [4]. The sulfate minerals kieserite, gypsum and other hydrated sulfates have been identified in OMEGA spectra in the layered terrains in Valles Marineris and Terra Meridiani [2]. These recent discoveries emphasize the importance of studying sulfate minerals as tracers of aqueous processes. The sulfate-rich rock outcrops observed in Meridiani Planum may have formed in an acidic environment similar to acid rock drainage environments on Earth [5]. Because microorganisms typically are involved in the oxidation of sulfides to sulfates in terrestrial sites, sulfate-rich rock outcrops on Mars may be a good location to search for evidence of past life on that planet. Whether or not life evolved on Mars, following the trail of sulfate minerals will lead to a better understanding of aqueous processes and chemical weathering.

  13. Chondroitin Sulfate Perlecan Enhances Collagen Fibril Formation

    DEFF Research Database (Denmark)

    Kvist, A. J.; Johnson, A. E.; Mörgelin, M.

    2006-01-01

    produced in the presence of perlecan. Interestingly, the enhancement of collagen fibril formation is independent on the core protein and is mimicked by chondroitin sulfate E but neither by chondroitin sulfate D nor dextran sulfate. Furthermore, perlecan chondroitin sulfate contains the 4,6-disulfated......Inactivation of the perlecan gene leads to perinatal lethal chondrodysplasia. The similarity to the phenotypes of the Col2A1 knock-out and the disproportionate micromelia mutation suggests perlecan involvement in cartilage collagen matrix assembly. We now present a mechanism for the defect...... in collagen type II fibril assembly by perlecan-null chondrocytes. Cartilage perlecan is a heparin sulfate or a mixed heparan sulfate/chondroitin sulfate proteoglycan. The latter form binds collagen and accelerates fibril formation in vitro, with more defined fibril morphology and increased fibril diameters...

  14. Sulfation and biological activities of konjac glucomannan.

    Science.gov (United States)

    Bo, Surina; Muschin, Tegshi; Kanamoto, Taisei; Nakashima, Hideki; Yoshida, Takashi

    2013-05-15

    The sulfation of konjac glucomannan and its anti-HIV and blood anticoagulant activities were investigated. Konjac glucomannan is a polysaccharide occurring naturally in konjac plant tubers and has high molecular weights. Solubility in water is very low, and the aqueous solutions at low concentrations have high viscosity. Before sulfation, hydrolysis by diluted sulfuric acid was carried out to decrease the molecular weights of M¯n=19.2 × 10(4)-0.2 × 10(4). Sulfation with piperidine-N-sulfonic acid or SO3-pyridine complex gave sulfated konjac glucomannans with molecular weights of M¯n=1.0 × 10(4)-0.4 × 10(4) and degrees of sulfation (DS) of 1.3-1.4. It was found that the sulfated konjac glucomannans had potent anti-HIV activity at a 50% effective concentration, (EC50) of 1.2-1.3 μg/ml, which was almost as high as that of an AIDS drug, ddC, whose EC50=3.2 μg/ml, and moderate blood anticoagulant activity, AA=0.8-22.7 units/mg, compared to those of standard sulfated polysaccharides, curdlan (10 units/mg) and dextran (22.7 units/mg) sulfates. Structural analysis of sulfated konjac glucomannans with negatively charged sulfated groups was performed by high resolution NMR, and the interaction between poly-l-lysine with positively charged amino groups as a model compound of proteins and peptides was measured by surface plasmon resonance measurement, suggesting that the sulfated konjac glucomannans had a high binding stability on immobilized poly-l-lysine. The binding of sulfated konjac glucomannan was concentration-dependent, and the biological activity of the sulfated konjac glucomannans may be due to electrostatic interaction between the sulfate and amino groups.

  15. Adsorption of Sulfate and Fluoride in Relation to Some Surface Chemical Properties of Oxisols

    Institute of Scientific and Technical Information of China (English)

    ZHANGGANG-YA; ZHANGXIAO-NIAN; 等

    1991-01-01

    In the present work,the adsorption of sulfate and fluoride by two oxisols was studied,and during the adsorption OH- released from soils were measured and the change in surface charge carried by one of the soils after the adsorption of fluoride was examined.The results show that the adsorption of sulfate by oxisols and the release of OH- from oxisols both increased with the increase of sulfate added at a constant pH,but decreased when pH became higher gradually.The adsorption and release both decreased markedly after removal of iron oxide.The ratio of OH- to SO42- for Fe-removed soils decreased to 15-34% of the original soils.These results suggest that iron oxide was the chief carrier of hydroxyl proups capable of ligand exchange with sulfate in oxisols. Compared with sulfate,however,the amount of fluoride adsorbed,OH- released during the adsorption of fluoride and the ratio of OH- to F- were much larger.The effect of iron oxide on the adsorption of fluoride by oxisols was smaller than that on the adsorption of sulfate.The ratios of OH- to F- for an oxisol from Brazil were 0.62 and 0.48 respectively before and after removal of free iron oxides.This implied that iron oxide only provided a small amount of exchangeable hydroxyl groups capable of ligand exchange with fluoride in oxisol.The research results indicate that among the factors inducing the changes in some properties of oxisols after adsorption of fluoride,the role became less important in the sequence of the release of OH-> the increase of negative charge> the decrease of positive charge.

  16. LigandRNA: computational predictor of RNA-ligand interactions.

    Science.gov (United States)

    Philips, Anna; Milanowska, Kaja; Lach, Grzegorz; Bujnicki, Janusz M

    2013-12-01

    RNA molecules have recently become attractive as potential drug targets due to the increased awareness of their importance in key biological processes. The increase of the number of experimentally determined RNA 3D structures enabled structure-based searches for small molecules that can specifically bind to defined sites in RNA molecules, thereby blocking or otherwise modulating their function. However, as of yet, computational methods for structure-based docking of small molecule ligands to RNA molecules are not as well established as analogous methods for protein-ligand docking. This motivated us to create LigandRNA, a scoring function for the prediction of RNA-small molecule interactions. Our method employs a grid-based algorithm and a knowledge-based potential derived from ligand-binding sites in the experimentally solved RNA-ligand complexes. As an input, LigandRNA takes an RNA receptor file and a file with ligand poses. As an output, it returns a ranking of the poses according to their score. The predictive power of LigandRNA favorably compares to five other publicly available methods. We found that the combination of LigandRNA and Dock6 into a "meta-predictor" leads to further improvement in the identification of near-native ligand poses. The LigandRNA program is available free of charge as a web server at http://ligandrna.genesilico.pl.

  17. Synthesis and characterization of a cadmium(II)-organic supramolecular coordination compound based on the multifunctional 2-amino-5-sulfobenzoic acid ligand.

    Science.gov (United States)

    Yuan, Gan Yin; Zhang, Lei; Wang, Meng Jie; Zhang, Kou Lin

    2016-12-01

    Much attention has been paid by chemists to the construction of supramolecular coordination compounds based on the multifunctional ligand 5-sulfosalicylic acid (H3SSA) due to the structural and biological interest of these compounds. However, no coordination compounds have been reported for the multifunctional amino-substituted sulfobenzoate ligand 2-amino-5-sulfobenzoic acid (H2asba). We expected that H2asba could be a suitable building block for the assembly of supramolecular networks due to its interesting structural characteristics. The reaction of cadmium(II) nitrate with H2asba in the presence of the auxiliary flexible dipyridylamide ligand N,N'-bis[(pyridin-4-yl)methyl]oxamide (4bpme) under ambient conditions formed a new mixed-ligand coordination compound, namely bis(3-amino-4-carboxybenzenesulfonato-κO(1))diaquabis{N,N'-bis[(pyridin-4-yl)methyl]oxamide-κN}cadmium(II)-N,N'-bis[(pyridin-4-yl)methyl]oxamide-water (1/1/4), [Cd(C7H6NO5S)2(C14H14N4O2)2(H2O)2]·C14H14N4O2·4H2O, (1), which was characterized by single-crystal and powder X-ray diffraction analysis (PXRD), FT-IR spectroscopy, thermogravimetric analysis (TG), and UV-Vis and photoluminescence spectroscopic analyses in the solid state. The central Cd(II) atom in (1) occupies a special position on a centre of inversion and exhibits a slightly distorted octahedral geometry, being coordinated by two N atoms from two monodentate 4bpme ligands, four O atoms from two monodentate 4-amino-3-carboxybenzenesulfonate (Hasba(-)) ligands and two coordinated water molecules. Interestingly, complex (1) further extends into a threefold polycatenated 0D→2D (0D is zero-dimensional and 2D is two-dimensional) interpenetrated supramolecular two-dimensional (4,4) layer through intermolecular hydrogen bonding. The interlayer hydrogen bonding further links adjacent threefold polycatenated two-dimensional layers into a three-dimensional network. The optical properties of complex (1) indicate that it may be used as a

  18. Modeling of ferric sulfate decomposition and sulfation of potassium chloride during grate‐firing of biomass

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Jappe Frandsen, Flemming

    2013-01-01

    Ferric sulfate is used as an additive in biomass combustion to convert the released potassium chloride to the less harmful potassium sulfate. The decomposition of ferric sulfate is studied in a fast heating rate thermogravimetric analyzer and a volumetric reaction model is proposed to describe...... the process. The yields of sulfur oxides from ferric sulfate decomposition under boiler conditions are investigated experimentally, revealing a distribution of approximately 40% SO3 and 60% SO2. The ferric sulfate decomposition model is combined with a detailed kinetic model of gas‐phase KCl sulfation...... and a model of K2SO4 condensation to simulate the sulfation of KCl by ferric sulfate addition. The simulation results show good agreements with experiments conducted in a biomass grate‐firing reactor. The results indicate that the SO3 released from ferric sulfate decomposition is the main contributor to KCl...

  19. Analysis of macromolecules, ligands and macromolecule-ligand complexes

    Science.gov (United States)

    Von Dreele, Robert B [Los Alamos, NM

    2008-12-23

    A method for determining atomic level structures of macromolecule-ligand complexes through high-resolution powder diffraction analysis and a method for providing suitable microcrystalline powder for diffraction analysis are provided. In one embodiment, powder diffraction data is collected from samples of polycrystalline macromolecule and macromolecule-ligand complex and the refined structure of the macromolecule is used as an approximate model for a combined Rietveld and stereochemical restraint refinement of the macromolecule-ligand complex. A difference Fourier map is calculated and the ligand position and points of interaction between the atoms of the macromolecule and the atoms of the ligand can be deduced and visualized. A suitable polycrystalline sample of macromolecule-ligand complex can be produced by physically agitating a mixture of lyophilized macromolecule, ligand and a solvent.

  20. Ligand-Receptor Interactions

    CERN Document Server

    Bongrand, Pierre

    2008-01-01

    The formation and dissociation of specific noncovalent interactions between a variety of macromolecules play a crucial role in the function of biological systems. During the last few years, three main lines of research led to a dramatic improvement of our understanding of these important phenomena. First, combination of genetic engineering and X ray cristallography made available a simultaneous knowledg of the precise structure and affinity of series or related ligand-receptor systems differing by a few well-defined atoms. Second, improvement of computer power and simulation techniques allowed extended exploration of the interaction of realistic macromolecules. Third, simultaneous development of a variety of techniques based on atomic force microscopy, hydrodynamic flow, biomembrane probes, optical tweezers, magnetic fields or flexible transducers yielded direct experimental information of the behavior of single ligand receptor bonds. At the same time, investigation of well defined cellular models raised the ...

  1. Excited state intramolecular proton transfer (ESIPT) in six-coordinated zinc(ii)-quinoxaline complexes with ligand hydrogen bonds: their fluorescent properties sensitive to axial positions.

    Science.gov (United States)

    Sakai, Ken-Ichi; Takahashi, Sami; Kobayashi, Ataru; Akutagawa, Tomoyuki; Nakamura, Takayoshi; Dosen, Masaaki; Kato, Masako; Nagashima, Umpei

    2010-02-28

    Zinc(ii)-quinoxaline complexes, [Zn(hqxc)(2)(py)(2)] and [Zn(hqxc)(2)(DMSO)(2)] (hqxc = 3-hydroxy-2-quinoxalinecarboxylate, py = pyridine, DMSO = dimethyl sulfoxide), were prepared and characterized by X-ray crystallography and fluorescence spectroscopy. In both complexes, the zinc ion is six-coordinated by two equatorial bidentate hqxc ligands with an intramolecular hydrogen bond and two axial monodentate ligands such as pyridine or DMSO. In spite of similar coordination geometries, there is a remarkable difference between their solid-state fluorescent properties. The pyridine complex is strongly fluorescent (fluorescence quantum yield Phi = 0.22), giving rise to a significantly Stokes-shifted spectrum. From its thin film photopumped by a nitrogen gas laser, amplified spontaneous emission was observed. These results suggest that the fluorescence occurs by way of excited-state intramolecular proton-transfer (ESIPT) in the hydrogen bond of hqxc. On the other hand, the DMSO complex shows fluorescent intensity (Phi = 0.08) lower than that of the pyridine complex, and shows normal emission in addition to ESIPT emission. From IR measurements for these complexes, it is concluded that axial ligands influence the hydrogen bond strength of the equatorial hqxc ligand via zinc and thus the ESIPT efficiency.

  2. Quinoxaline-2-carboxamide as a carrier ligand in two new platinum(II) compounds: Synthesis, crystal structure, cytotoxic activity and DNA interaction.

    Science.gov (United States)

    Marqués-Gallego, Patricia; Gamiz-Gonzalez, M Amparo; Fortea-Pérez, Francisco R; Lutz, Martin; Spek, Anthony L; Pevec, Andrej; Kozlevčar, Bojan; Reedijk, Jan

    2010-06-01

    The search for platinum compounds structurally different from cisplatin has led to two new platinum(II) compounds containing quinoxaline-2-carboxamide as a carrier ligand, i.e. cis-[Pt(qnxca)(MeCN)Cl2] (1) and the [Pt(qnxca-H)(dmso)Cl] (2). Both compounds have been synthesized and characterized using different spectroscopic methods. In addition, single-crystal structures have been determined by X-Ray diffraction for both compounds. In each case a square planar Pt(II) is present; in (1) the qnxca is monodentate and neutral, whereas in (2) the ligand has lost a hydrogen, to form the anionic chelating ligand abbreviated as qnxca-H. The biological activity of both compounds has been investigated in a panel of seven human tumour cells, displaying poor cytotoxic activity, compared to cisplatin. The interaction of the new compounds with 1 or 2 equiv. of 9-ethylguanine has been studied using (1)H NMR, (195)Pt NMR and ESI-MS spectroscopy, finding poor reactivity of 1 towards the model base, forming only the monosubstituted adduct. Surprisingly, compound 2, which is more sterically crowded, interacts more efficiently with the 9-EtG, forming a bifunctional adduct with two 9-EtG with substitution of the dmso and the chloride ligand. Unwinding studies of pUC19 plasmid DNA by compound 1 show similar unwinding properties to cisplatin.

  3. Therapeutic androgen receptor ligands

    OpenAIRE

    Allan, George F.; Sui, Zhihua

    2003-01-01

    In the past several years, the concept of tissue-selective nuclear receptor ligands has emerged. This concept has come to fruition with estrogens, with the successful marketing of drugs such as raloxifene. The discovery of raloxifene and other selective estrogen receptor modulators (SERMs) has raised the possibility of generating selective compounds for other pathways, including androgens (that is, selective androgen receptor modulators, or SARMs).

  4. A Hirshfeld surface analysis, crystal structure and physicochemical studies of a new Cd(II) complex with the 2-amino-4-methylpyrimidine ligand

    Science.gov (United States)

    Klai, Kacem; Kaabi, Kamel; Kaminsky, Werner; Jelsch, Christian; Lefebvre, Frédéric; Ben Nasr, Cherif

    2017-01-01

    A new Cd(II) complex with the monodentate ligand 2-amino-4-methylpyrimidine, [Cd(NO3)2(C5N3H7)2(H2O)2], has been prepared and characterized by single crystal X-ray diffraction, elemental analysis, CP-MAS NMR and IR spectroscopy. The basic coordination patterns of the 2-amino-4-methylpyrimidine coordinated metal cations are slightly distorted octahedra in this compound. The crystal structure is characterized by CdN2O4 octahedra interconnected via O-H…O and O-H…N hydrogen bonds to form layers parallel to the (b, c) plane. The crystal structure is stabilized by sets of hydrogen bonds, one of which is trifurcated. Intermolecular interactions were investigated by Hirshfeld surfaces. The 13C and 15N CP-MAS NMR spectra are discussed and the vibrational absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were derived.

  5. The Conjugation Stress of Ligand via Metal Core as the Cause of Changes in the Reactivity of Coordinated 1-Hetero-1,3-Dienes

    Directory of Open Access Journals (Sweden)

    A.I. Kuramshin

    2016-06-01

    Full Text Available Using quantum-chemical calculations carried out for interpretation of the experimentally discovered reactivity of 1-hetero-1,3-dienes that are mono- and bidentally coordinated with the transition metal core, we have revealed that the difference in hydrophosphorylation directions of the free organic molecule and the same molecule involved in the coordination sphere of the transition metal can be explained by either weakening or complete loss of conjugation between the C=C and C=X fragments as a result of coordination. In the case of monodentate coordination of heterodiene with the transition metal according to the eta(2(C,C-type, the conjugation weakening is suggested to be maximum for the transition metal characterized by the minimum electronegativity, which predetermines the increased contribution of the metalcyclopropane resonance structure into the general bonding mode. Organometallic compounds having the heterodiene ligand bidentally coordinated demonstrate the conjugation weakening parallel to the metal radius.

  6. Synthesis and crystal structure of Cu(II and Co(II complexes with 1,3-dimethyl-pyrazole-5-carboxylic acid ligand

    Directory of Open Access Journals (Sweden)

    Jaćimović Željko K.

    2015-01-01

    Full Text Available In the reaction of 1,3-dimethyl-pyrazole-5-carboxylic acid (HL with M(OAc2•4H2O, (M = Cu, Co two novel complexes have been prepared, square-planar [CuL2(H2O2] and octahedral [CoL2(MeOH4]. The crystal structures have been determined by single-crystal X-ray diffraction. In both complexes the deprotonated acid displays monodentate coordination to the metal ions. According to the results of CSD survey this is the first structural report on the metal complexes with N1-substituted pyrazole-5-carboxylic ligand. [Projekat Ministarstva nauke Republike Srbije, br. 172014 i br. 172035

  7. Imidazoline receptors ligands

    Directory of Open Access Journals (Sweden)

    Agbaba Danica

    2012-01-01

    Full Text Available Extensive biochemical and pharmacological studies have determined three different subtypes of imidazoline receptors: I1-imidazoline receptors (I1-IR involved in central inhibition of sympathicus that produce hypotensive effect; I2-imidazoline receptors (I2-IR modulate monoamine oxidase B activity (MAO-B; I3-imidazoline receptors (I3-IR regulate insulin secretion from pancreatic β-cells. Therefore, the I1/I2/I3 imidazoline receptors are selected as new, interesting targets for drug design and discovery. Novel selective I1/I2/I3 agonists and antagonists have been recently developed. In the present review, we provide a brief update to the field of imidazoline research, highlighting some of the chemical diversity and progress made in the 2D-QSAR, 3D-QSAR and quantitative pharmacophore development studies of I1-IR and I2-IR imidazoline receptor ligands. Theoretical studies of I3-IR ligands are not yet performed because of insufficient number of synthesized I3-IR ligands.

  8. Inhibition of synthesis of heparan sulfate by selenate: Possible dependence on sulfation for chain polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, C.P.; Nader, H.B. (Paulist School of Medicine, Sao Paulo (Brazil)); Buonassisi, V.; Colburn, P. (W. Alton Jones Cell Science Center, Lake Placid, NY (USA))

    1988-01-01

    Selenate, a sulfation inhibitor, blocks the synthesis of heparan sulfate and chondroitin sulfate by cultured endothelial cells. In contrast, selenate does not affect the production of hyaluronic acid, a nonsulfated glycosaminoglycan. No differences in molecular weight, ({sup 3}H)glucosamine/({sup 35}S)sulfuric acid ratios, or disaccharide composition were observed when the heparan sulfate synthesized by selenate-treated cells was compared with that of control cells. The absence of undersulfated chains in preparations from cultures exposed to selenate supports the concept that, in the intact cell, the polymerization of heparan sulfate might be dependent on the sulfation of the saccharide units added to the growing glycosaminoglycan chain.

  9. Intrahepatic cholestasis of pregnancy levels of sulfated progesterone metabolites inhibit farnesoid X receptor resulting in a cholestatic phenotype.

    Science.gov (United States)

    Abu-Hayyeh, Shadi; Papacleovoulou, Georgia; Lövgren-Sandblom, Anita; Tahir, Mehreen; Oduwole, Olayiwola; Jamaludin, Nurul Akmal; Ravat, Sabiha; Nikolova, Vanya; Chambers, Jenny; Selden, Clare; Rees, Myrddin; Marschall, Hanns-Ulrich; Parker, Malcolm G; Williamson, Catherine

    2013-02-01

    Intrahepatic cholestasis of pregnancy (ICP) is the most prevalent pregnancy-specific liver disease and is associated with an increased risk of adverse fetal outcomes, including preterm labor and intrauterine death. The endocrine signals that cause cholestasis are not known but 3α-sulfated progesterone metabolites have been shown to be elevated in ICP, leading us to study the impact of sulfated progesterone metabolites on farnesoid X receptor (FXR)-mediated bile acid homeostasis pathways. Here we report that the 3β-sulfated progesterone metabolite epiallopregnanolone sulfate is supraphysiologically raised in the serum of ICP patients. Mice challenged with cholic acid developed hypercholanemia and a hepatic gene expression profile indicative of FXR activation. However, coadministration of epiallopregnanolone sulfate with cholic acid exacerbated the hypercholanemia and resulted in aberrant gene expression profiles for hepatic bile acid-responsive genes consistent with cholestasis. We demonstrate that levels of epiallopregnanolone sulfate found in ICP can function as a partial agonist for FXR, resulting in the aberrant expression of bile acid homeostasis genes in hepatoma cell lines and primary human hepatocytes. Furthermore, epiallopregnanolone sulfate inhibition of FXR results in reduced FXR-mediated bile acid efflux and secreted FGF19. Using cofactor recruitment assays, we show that epiallopregnanolone sulfate competitively inhibits bile acid-mediated recruitment of cofactor motifs to the FXR-ligand binding domain. Our results reveal a novel molecular interaction between ICP-associated levels of the 3β-sulfated progesterone metabolite epiallopregnanolone sulfate and FXR that couples the endocrine component of pregnancy in ICP to abnormal bile acid homeostasis. Copyright © 2012 American Association for the Study of Liver Diseases.

  10. Synthesis, characterization and crystal structure of four new asymmetric triazene ligands: An example of linear HII complex with H... secondary bonding interactions

    Indian Academy of Sciences (India)

    Mohammad Reza Melardi; Fatemeh Baber Shamsi Mogoii; Ayoob Babaii Sajirani; Jafar Attar Gharamaleki; Behrouz Notash; Mohammad Kazem Rofouei

    2015-12-01

    In this work, the asymmetric ligands [1-(phenyl)-3-(2-nitro-4-methylphenyl)]triazene (1), [1-(4-methylphenyl)-3-(2-nitro-4-methylphenyl)]triazene (2), [1-(4-ethylphenyl)-3-(2-nitro-4-methylphenyl)]triazene (3) and [1-(4-ethoxyphenyl)-3-(2-nitro-4-methylphenyl)]triazene (4), were synthesized. The reaction of the ligand (3) with HgCl2 in methanol resulted in the formation of the [HgL2] complex, (5). All compounds were characterized by means of CHN analysis, FT-IR, 1H NMR, 13C NMR spectroscopy. In addition, the crystal structures of the ligands (2) to (4) were investigated by single crystal X-ray analysis. In the solid state, all ligands exhibited trans conformation about the –N=N– double bond. The HgII complex (5) crystallized in monoclinic system with 2/ space group. The triazene ligand was found to be deprotonated prior to coordination and acts as monodentate ligand. The HgII which lies on inversion center (site symmetry $\\bar{1}$), is surrounded by two N atoms from L ligands forming a linear geometry. The other two Hg–N bonds are relatively longer and can only be regarded as weak secondary bonds. Also, Hg-3-arene -interactions are present in this compound. Hydrogen bonds, · · · and C–H· · · stacking interactions help in the stabilization of the resulted frameworks. These C–H· · · edge-to-face interactions are present with H· · · distance of 3.00 Å.

  11. Evaluating Deterioration of Concrete by Sulfate Attack

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Effects of factors such as water to cement ratio, fly ash and silica fume on the resistance of concrete to sulfate attack were investigated by dry-wet cycles and immersion method. The index of the resistance to sulfate attack was used to evaluate the deterioration degree of concrete damaged by sulfate. The relationship between the resistance of concrete to sulfate attack and its permeability/porosity were analyzed as well as its responding mechanism. Results show that the depth of sulfate crystal attack from surface to inner of concrete can be reduced by decreasing w/c and addition of combining fly ash with silica fume. The variation of relative elastic modulus ratio and relative flexural strength ratio of various specimens before and after being subjected to sulfate attack was compared.

  12. Depolymerization of sulfated polysaccharides under hydrothermal conditions.

    Science.gov (United States)

    Morimoto, Minoru; Takatori, Masaki; Hayashi, Tetsuya; Mori, Daiki; Takashima, Osamu; Yoshida, Shinichi; Sato, Kimihiko; Kawamoto, Hitoshi; Tamura, Jun-ichi; Izawa, Hironori; Ifuku, Shinsuke; Saimoto, Hiroyuki

    2014-01-30

    Fucoidan and chondroitin sulfate, which are well known sulfated polysaccharides, were depolymerized under hydrothermal conditions (120-180°C, 5-60min) as a method for the preparation of sulfated polysaccharides with controlled molecular weights. Fucoidan was easily depolymerized, and the change of the molecular weight values depended on the reaction temperature and time. The degree of sulfation and IR spectra of the depolymerized fucoidan did not change compared with those of untreated fucoidan at reaction temperatures below 140°C. However, fucoidan was partially degraded during depolymerization above 160°C. Nearly the same depolymerization was observed for chondroitin sulfate. These results indicate that hydrothermal treatment is applicable for the depolymerization of sulfated polysaccharides, and that low molecular weight products without desulfation and deformation of the initial glycan structures can be obtained under mild hydrothermal conditions.

  13. Trihydrated Complex of Tetrabenzimidazole Copper(Ⅱ) Sulfate

    Institute of Scientific and Technical Information of China (English)

    JIAN Fang-fang; WANG Huan-xiang; XIAO Hai-lian; JIAO Kui

    2005-01-01

    A Trihydrated complex of benzimidazole copper(Ⅱ) sulfate [(C7H6N2)4CuSO4]·3H2O was synthesized and structurally characterized. The crystal structure of this compound is built up of six solvated water molecules and two dissimilar copper ions identified as Cu1 and Cu2. The coordination geometry of copper(Ⅱ) is a slightly distorted square pyramid. The four equivalent tertiary nitrogen atoms of the benzimidazole ligand form an equatorial plane, while the oxygen atoms of sulfato occupy the axial site. In the solid state, the title compound forms a three dimensional network structure via hydrogen bonds. The benzimidazole, sulfato ion and H2O moieties are connected by the intermolecular hydrogen bonds. The (EPR) spectrum shows axial symmetry with g⊥=2.039 and g∥=2.285. Variable temperature magnetic susceptibility shows that there is a weak antiferromagnetic interaction between the neighboring copper(Ⅱ) ions.

  14. Sonic hedgehog processing and release are regulated by glypican heparan sulfate proteoglycans.

    Science.gov (United States)

    Ortmann, Corinna; Pickhinke, Ute; Exner, Sebastian; Ohlig, Stefanie; Lawrence, Roger; Jboor, Hamodah; Dreier, Rita; Grobe, Kay

    2015-06-15

    All Hedgehog morphogens are released from producing cells, despite being synthesized as N- and C-terminally lipidated molecules, a modification that firmly tethers them to the cell membrane. We have previously shown that proteolytic removal of both lipidated peptides, called shedding, releases bioactive Sonic hedgehog (Shh) morphogens from the surface of transfected Bosc23 cells. Using in vivo knockdown together with in vitro cell culture studies, we now show that glypican heparan sulfate proteoglycans regulate this process, through their heparan sulfate chains, in a cell autonomous manner. Heparan sulfate specifically modifies Shh processing at the cell surface, and purified glycosaminoglycans enhance the proteolytic removal of N- and C-terminal Shh peptides under cell-free conditions. The most likely explanation for these observations is direct Shh processing in the extracellular compartment, suggesting that heparan sulfate acts as a scaffold or activator for Shh ligands and the factors required for their turnover. We also show that purified heparan sulfate isolated from specific cell types and tissues mediates the release of bioactive Shh from pancreatic cancer cells, revealing a previously unknown regulatory role for these versatile molecules in a pathological context.

  15. Renal heparan sulfate proteoglycans modulate fibroblast growth factor 2 signaling in experimental chronic transplant dysfunction.

    Science.gov (United States)

    Katta, Kirankumar; Boersema, Miriam; Adepu, Saritha; Rienstra, Heleen; Celie, Johanna W A M; Mencke, Rik; Molema, Grietje; van Goor, Harry; Berden, Jo H M; Navis, Gerjan; Hillebrands, Jan-Luuk; van den Born, Jacob

    2013-11-01

    Depending on the glycan structure, proteoglycans can act as coreceptors for growth factors. We hypothesized that proteoglycans and their growth factor ligands orchestrate tissue remodeling in chronic transplant dysfunction. We have previously shown perlecan to be selectively up-regulated in the glomeruli and arteries in a rat renal transplantation model. Using the same model, here we present quantitative RT-PCR profiling data on proteoglycans and growth factors from laser-microdissected glomeruli, arterial tunicae mediae, and neointimae at 12 weeks after transplantation. In glomeruli and neointimae of allografts, selective induction of the matrix heparan sulfate proteoglycan perlecan was observed, along with massive accumulation of fibroblast growth factor 2 (FGF2). Profiling the heparan sulfate polysaccharide side chains revealed conversion from a non-FGF2-binding heparan sulfate phenotype in control and isografted kidneys toward a FGF2-binding phenotype in allografts. In vitro experiments with perlecan-positive rat mesangial cells showed that FGF2-induced proliferation is dependent on sulfation and can be inhibited by exogenously added heparan sulfate. These findings indicate that matrix proteoglycans such as perlecan serve as functional docking platforms for FGF2 in chronic transplant dysfunction. We speculate that heparin-like glycomimetics could be a promising intervention to retard development of glomerulosclerosis and neointima formation in chronic transplant dysfunction.

  16. Polymeric networks of copper(II) phenylmalonate with heteroaromatic n-donor ligands: synthesis, crystal structure, and magnetic properties.

    Science.gov (United States)

    Pasán, Jorge; Sanchiz, Joaquín; Ruiz-Pérez, Catalina; Lloret, Francesc; Julve, Miguel

    2005-10-31

    Two new phenylmalonate-bridged copper(II) complexes with the formulas [Cu(4,4'-bpy)(Phmal)](n).2nH(2)O (1) and [Cu(2,4'-bpy)(Phmal)(H(2)O)](n)() (2) (Phmal = phenylmalonate dianion, 4,4'-bpy = 4,4'-bipyridine, 2,4'-bpy = 2,4'-bipyridine) have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in monoclinic space group P2(1), Z = 4, with unit cell parameters of a = 9.0837(6) Angstroms, b = 9.3514(4) Angstroms, c = 11.0831(8) Angstroms, and beta = 107.807(6) degrees , whereas complex 2 crystallizes in orthorhombic space group C2cb, Z = 8, with unit cell parameters of a = 10.1579(7) Angstroms, b = 10.3640(8) Angstroms, and c = 33.313(4) Angstroms. The structures of 1 and 2 consist of layers of copper(II) ions with bridging bis-monodentate phenylmalonate (1 and 2) and 4,4'-bpy (1) ligands and terminal monodentate 2,4'-bpy (2) groups. Each layer in 1 contains rectangles with dimensions of 11.08 x 4.99 Angstroms(2), the edges being defined by the Phmal and 4,4'-bpy ligands. The intralayer copper-copper separations in 1 through the anti-syn equatorial-apical carboxylate-bridge and the 4,4'-bpy molecule are 4.9922(4) and 11.083(1) Angstroms, respectively. The anti-syn equatorial-equatorial carboxylate bridge links the copper(II) atoms in complex 2 within each layer with a mean copper-copper separation of 5.3709(8) Angstroms. The presence of 2,4'-bpy as a terminal ligand accounts for the large interlayer separation of 15.22 Angstroms. The copper(II) environment presents a static pseudo-Jahn-Teller disorder which has been studied by EPR and low-temperature X-ray diffraction. Magnetic susceptibility measurements of both compounds in the temperature range 2-290 K show the occurrence of weak antiferromagnetic [J = -0.59(1) cm(-1) (1)] and ferromagnetic [J = +0.77(1) cm(-1) (2)] interactions between the copper(II) ions. The conformation of the phenylmalonate-carboxylate bridge and other structural factors, such as the planarity of the exchange

  17. Bexarotene ligand pharmaceuticals.

    Science.gov (United States)

    Hurst, R E

    2000-12-01

    Bexarotene (LGD-1069), from Ligand, was the first retinoid X receptor (RXR)-selective, antitumor retinoid to enter clinical trials. The company launched the drug for the treatment of cutaneous T-cell lymphoma (CTCL), as Targretin capsules, in the US in January 2000 [359023]. The company filed an NDA for Targretin capsules in June 1999, and for topical gel in December 1999 [329011], [349982] specifically for once-daily oral administration for the treatment of patients with early-stage CTCL who have not tolerated other therapies, patients with refractory or persistent early stage CTCL and patients with refractory advanced stage CTCL. The FDA approved Targretin capsules at the end of December 1999 for once-daily oral treatment of all stages of CTCL in patients refractory to at least one prior systemic therapy, at an initial dose of 300 mg/m2/day. After an NDA was submitted in December 1999 for Targretin gel, the drug received Priority Review status for use as a treatment of cutaneous lesions in patients with stage IA, IB or IIA CTCL [354836]. The FDA issued an approvable letter in June 2000, and granted marketing clearance for CTCL in the same month [370687], [372768], [372769], [373279]. Ligand had received Orphan Drug designation for this indication [329011]. At the request of the FDA, Ligand agreed to carry out certain post-approval phase IV and pharmacokinetic studies [351604]. The company filed an MAA with the EMEA for Targretin Capsules to treat lymphoma in November 1999 [348944]. The NDA for Targretin gel is based on a multicenter phase III trial that was conducted in the US, Canada, Europe and Australia involving 50 patients and a multicenter phase I/II clinical program involving 67 patients. Targretin gel was evaluated for the treatment of patients with early stage CTCL (IA-IIA) who were refractory to, intolerant to, or reached a response plateau for at least 6 months on at least two prior therapies. Efficacy results exceeded the protocol-defined response

  18. Significant role of organic sulfur in supporting sedimentary sulfate reduction in low-sulfate environments

    Science.gov (United States)

    Fakhraee, Mojtaba; Li, Jiying; Katsev, Sergei

    2017-09-01

    Dissimilatory sulfate reduction (DSR) is a major carbon mineralization pathway in aquatic sediments, soils, and groundwater, which regulates the production of hydrogen sulfide and the mobilization rates of biologically important elements such as phosphorus and mercury. It has been widely assumed that water-column sulfate is the main sulfur source to fuel this reaction in sediments. While this assumption may be justified in high-sulfate environments such as modern seawater, we argue that in low-sulfate environments mineralization of organic sulfur compounds can be an important source of sulfate. Using a reaction-transport model, we investigate the production of sulfate from sulfur-containing organic matter for a range of environments. The results show that in low sulfate environments (50%) of sulfate reduction. In well-oxygenated systems, porewater sulfate profiles often exhibit sub-interface peaks so that sulfate fluxes are directed out of the sediment. Our measurements in Lake Superior, the world's largest lake, corroborate this conclusion: offshore sediments act as sources rather than sinks of sulfate for the water column, and sediment DSR is supported entirely by the in-sediment production of sulfate. Sulfate reduction rates are correlated to the depth of oxygen penetration and strongly regulated by the supply of reactive organic matter; rate co-regulation by sulfate availability becomes appreciable below 500 μM level. The results indicate the need to consider the mineralization of organic sulfur in the biogeochemical cycling in low-sulfate environments, including several of the world's largest freshwater bodies, deep subsurface, and possibly the sulfate-poor oceans of the Early Earth.

  19. Mixed ligand complexation of some transition metal ions in solution and solid state: Spectral characterization, antimicrobial, antioxidant, DNA cleavage activities and molecular modeling

    Science.gov (United States)

    Shobana, Sutha; Dharmaraja, Jeyaprakash; Selvaraj, Shanmugaperumal

    2013-04-01

    Equilibrium studies of Ni(II), Cu(II) and Zn(II) mixed ligand complexes involving a primary ligand 5-fluorouracil (5-FU; A) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) as co-ligands(B) were carried out pH-metrically in aqueous medium at 310 ± 0.1 K with I = 0.15 M (NaClO4). In solution state, the stoichiometry of MABH, MAB and MAB2 species have been detected. The primary ligand(A) binds the central M(II) ions in a monodentate manner whereas him, bim, hist and his co-ligands(B) bind in mono, mono, bi and tridentate modes respectively. The calculated Δ log K, log X and log X' values indicate higher stability of the mixed ligand complexes in comparison to binary species. Stability of the mixed ligand complex equilibria follows the Irving-Williams order of stability. In vitro biological evaluations of the free ligand(A) and their metal complexes by well diffusion technique show moderate activities against common bacterial and fungal strains. Oxidative cleavage interaction of ligand(A) and their copper complexes with CT DNA is also studied by gel electrophoresis method in the presence of oxidant. In vitro antioxidant evaluations of the primary ligand(A), CuA and CuAB complexes by DPPH free radical scavenging model were carried out. In solid, the MAB type of M(II)sbnd 5-FU(A)sbnd his(B) complexes were isolated and characterized by various physico-chemical and spectral techniques. Both the magnetic susceptibility and electronic spectral analysis suggest distorted octahedral geometry. Thermal studies on the synthesized mixed ligand complexes show loss of coordinated water molecule in the first step followed by decomposition of the organic residues subsequently. XRD and SEM analysis suggest that the microcrystalline nature and homogeneous morphology of MAB complexes. Further, the 3D molecular modeling and analysis for the mixed ligand MAB complexes have also been carried out.

  20. Discovery of a Heparan sulfate 3- o -sulfation specific peeling reaction

    NARCIS (Netherlands)

    Huang, Yu; Mao, Yang; Zong, Chengli; Lin, Cheng; Boons, Geert Jan; Zaia, Joseph

    2015-01-01

    Heparan sulfate (HS) 3-O-sulfation determines the binding specificity of HS/heparin for antithrombin III and plays a key role in herpes simplex virus (HSV) infection. However, the low natural abundance of HS 3-O-sulfation poses a serious challenge for functional studies other than the two cases ment

  1. Involvement of highly sulfated chondroitin sulfate in the metastasis of the Lewis lung carcinoma cells.

    NARCIS (Netherlands)

    Li, F.; Dam, G.B. ten; Murugan, S.; Yamada, S.; Hashiguchi, T.; Mizumoto, S.; Oguri, K.; Okayama, M.; Kuppevelt, A.H.M.S.M. van; Sugahara, K.

    2008-01-01

    The altered expression of cell surface chondroitin sulfate (CS) and dermatan sulfate (DS) in cancer cells has been demonstrated to play a key role in malignant transformation and tumor metastasis. However, the functional highly sulfated structures in CS/DS chains and their involvement in the process

  2. A novel three-dimensional Zn(II) coordination polymer with 1,3,5-tris(imidazol-1-ylmethyl)benzene and cyclohexane-1,3,5-tricarboxylate ligands.

    Science.gov (United States)

    Zhong, Kai-Long

    2014-02-01

    In the Zn(II) compound poly[[bis(μ3-cyclohexane-1,3,5-tricarboxylato)bis[μ3-1,3,5-tris(imidazol-1-ylmethyl)benzene]trizinc(II)] hexahydrate], {[Zn3(C18H18N6)2(C9H9O6)2]·6H2O}n, based on mixed 1,3,5-tris(imidazol-1-ylmethyl)benzene and cyclohexane-1,3,5-tricarboxylate ligands, there are two types of crystallographically independent Zn(II) centres, one in a general position and one on a crystallographic twofold axis. They have similar fourfold distorted tetrahedral coordination geometries, ligated by two monodentate carboxylate groups from two cyclohexane-1,3,5-tricarboxylate ligands and by two N atoms from two 1,3,5-tris(imidazol-1-ylmethyl)benzene ligands. The cyclohexane-1,3,5-tricarboxylate anions link the Zn(II) cations to generate a two-dimensional layered metal-organic structure running parallel to the (201) plane. Adjacent layers are further connected by tripodal 1,3,5-tris(imidazol-1-ylmethyl)benzene ligands, resulting in a three-dimensional network. The solvent water molecules are linked to the cyclohexane-1,3,5-tricarboxylate ligands via water-carboxylate O-H···O hydrogen bonds.

  3. Trivalent lanthanide compounds with fluorinated thiolate ligands: Ln-F dative interactions vary with Ln and solvent.

    Science.gov (United States)

    Melman, Jonathan H; Rohde, Christa; Emge, Thomas J; Brennan, John G

    2002-01-14

    The fluorinated tris-thiolate compounds Ln(SC(6)F(5))(3) can be isolated as THF, pyridine, or DME coordination complexes. In THF, the larger Ce forms dimeric [(THF)(3)Ce(SC(6)F(5))(3)](2) (1) with bridging thiolate ligands, while the smaller lanthanides (Ln = Ho (2), Er (3)) form monometallic (THF)(3)Ln(SC(6)F(5))(3) compounds. There is a tendency for fluoride to coordinate to Ln throughout the lanthanide series (Ce-Er). The cerium compound 1 contains a pair of bridging thiolates connecting two eight-coordinate Ce(III) ions. Of the two terminal thiolates, only one exhibits a distinct Ce-F bond. In contrast, the Ho derivative (THF)(3)Ho(SC(6)F(5))(3) is a molecular compound in the solid state, with two monodentate thiolates and one thiolate that again coordinates through both S and F atoms. Incorporation of a stronger Lewis base reduces but does not necessarily eliminate the tendency to form Ln-F bonds. Structural characterization of the eight-coordinate (pyridine)(4)Sm(SC(6)F(5))(3) (4) reveals a single, clearly defined Ln-F interaction, while in (pyridine)(4)Yb(SC(6)F(5))(3) (5) there are no Yb-F bonds. In the structure of (DME)(2)Er(SC(6)F(5))(3) (6) the DME ligands completely displace F from the Er coordination sphere.

  4. A targeted glycan-related gene screen reveals heparan sulfate proteoglycan sulfation regulates WNT and BMP trans-synaptic signaling.

    Directory of Open Access Journals (Sweden)

    Neil Dani

    Full Text Available A Drosophila transgenic RNAi screen targeting the glycan genome, including all N/O/GAG-glycan biosynthesis/modification enzymes and glycan-binding lectins, was conducted to discover novel glycan functions in synaptogenesis. As proof-of-product, we characterized functionally paired heparan sulfate (HS 6-O-sulfotransferase (hs6st and sulfatase (sulf1, which bidirectionally control HS proteoglycan (HSPG sulfation. RNAi knockdown of hs6st and sulf1 causes opposite effects on functional synapse development, with decreased (hs6st and increased (sulf1 neurotransmission strength confirmed in null mutants. HSPG co-receptors for WNT and BMP intercellular signaling, Dally-like Protein and Syndecan, are differentially misregulated in the synaptomatrix of these mutants. Consistently, hs6st and sulf1 nulls differentially elevate both WNT (Wingless; Wg and BMP (Glass Bottom Boat; Gbb ligand abundance in the synaptomatrix. Anterograde Wg signaling via Wg receptor dFrizzled2 C-terminus nuclear import and retrograde Gbb signaling via synaptic MAD phosphorylation and nuclear import are differentially activated in hs6st and sulf1 mutants. Consequently, transcriptional control of presynaptic glutamate release machinery and postsynaptic glutamate receptors is bidirectionally altered in hs6st and sulf1 mutants, explaining the bidirectional change in synaptic functional strength. Genetic correction of the altered WNT/BMP signaling restores normal synaptic development in both mutant conditions, proving that altered trans-synaptic signaling causes functional differentiation defects.

  5. Fucoidans - sulfated polysaccharides of brown algae

    Energy Technology Data Exchange (ETDEWEB)

    Usov, Anatolii I; Bilan, M I [N.D.Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation)

    2009-08-31

    The methods of isolation of fucoidans and determination of their chemical structures are reviewed. The fucoidans represent sulfated polysaccharides of brown algae, the composition of which varies from simple fucan sulfates to complex heteropolysaccharides. The currently known structures of such biopolymers are presented. A variety of the biological activities of fucoidans is briefly summarised.

  6. Fucoidans — sulfated polysaccharides of brown algae

    Science.gov (United States)

    Usov, Anatolii I.; Bilan, M. I.

    2009-08-01

    The methods of isolation of fucoidans and determination of their chemical structures are reviewed. The fucoidans represent sulfated polysaccharides of brown algae, the composition of which varies from simple fucan sulfates to complex heteropolysaccharides. The currently known structures of such biopolymers are presented. A variety of the biological activities of fucoidans is briefly summarised.

  7. Primary mesenchyme cell migration requires a chondroitin sulfate/dermatan sulfate proteoglycan.

    Science.gov (United States)

    Lane, M C; Solursh, M

    1991-02-01

    Primary mesenchyme cell migration in the sea urchin embryo is inhibited by sulfate deprivation and exposure to exogenous beta-D-xylosides, two treatments known to disrupt proteoglycan synthesis. We show that in the developing sea urchin, exogenous xyloside affects the synthesis by the primary mesenchyme cells of a very large, cell surface chondroitin sulfate/dermatan sulfate proteoglycan. This proteoglycan is present in a partially purified fraction that restores migratory ability to defective cells in vitro. The integrity of this chondroitin sulfate/dermatan sulfate proteoglycan appears essential for primary mesenchyme cell migration since treatment of actively migrating cells with chondroitinase ABC reversibly inhibited their migration in vitro.

  8. Photochemistry of RuII 4,4'-bi-1,2,3-triazolyl (btz) complexes: crystallographic characterization of the photoreactive ligand-loss intermediate trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+.

    Science.gov (United States)

    Welby, Christine E; Armitage, Georgina K; Bartley, Harry; Wilkinson, Aaron; Sinopoli, Alessandro; Uppal, Baljinder S; Rice, Craig R; Elliott, Paul I P

    2014-07-01

    We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ(2) -btz)(κ(1) -btz)(NCMe)](2+) (1 a) that contains a monodentate chelate ligand. This and analogous complexes can be observed during the photolysis reactions of a family of complexes of the form [Ru({NN})(btz)(2)](2+) (1 a-d: btz=1,1'-dibenzyl-4,4'-bi-1,2,3-triazolyl; {NN}=a) 2,2'-bipyridyl (bpy), b) 4,4'-dimethyl-2,2'-bipyridyl (dmbpy), c) 4,4'-dimethoxy-2,2'-bipyridyl (dmeobpy), d) 1,10-phenanthroline (phen)). In acetonitrile solutions, 1 a-d eventually convert to the bis-solvento complexes trans-[Ru({NN})(btz)(NCMe)(2)](2+) (3 a-d) along with one equivalent of free btz, in a process in which the remaining coordinated bidentate ligands undergo a new rearrangement such that they become coplanar. X-ray crystal structure of 3 a and 3 d confirmed the co-planar arrangement of the {NN} and btz ligands and the trans coordination of two solvent molecules. These conversions proceed via the observed intermediate complexes 2 a-d, which are formed quantitatively from 1 a-d in a matter of minutes and to which they slowly revert back on being left to stand in the dark over several days. The remarkably long lifetime of the intermediate complexes (>12 h at 40 °C) allowed the isolation of 2 a in the solid state, and the complex to be crystallographically characterized. Similarly to the structures adopted by complexes 3 a and d, the bpy and κ(2) -btz ligands in 2 a coordinate in a square-planar fashion with the second monodentate btz ligand coordinated trans to an acetonitrile ligand.

  9. Metabolic Flexibility of Sulfate Reducing Bacteria

    Directory of Open Access Journals (Sweden)

    Caroline M. Plugge

    2011-05-01

    Full Text Available Dissimilatory sulfate-reducing prokaryotes (SRB are a very diverse group of anaerobic bacteria that are omnipresent in nature and play an imperative role in the global cycling of carbon and sulfur. In anoxic marine sediments sulfate reduction accounts for up to 50% of the entire organic mineralization in coastal and shelf ecosystems where sulfate diffuses several meters deep into the sediment. As a consequence, SRB would be expected in the sulfate-containing upper sediment layers, whereas methanogenic Archaea would be expected to succeed in the deeper sulfate-depleted layers of the sediment. Where sediments are high in organic matter, sulfate is depleted at shallow sediment depths, and biogenic methane production will occur. In the absence of sulfate, many SRB ferment organic acids and alcohols, producing hydrogen, acetate, and carbon dioxide, and may even rely on hydrogen- and acetate-scavenging methanogens to convert organic compounds to methane. SRB can establish two different life styles, and these can be termed as sulfidogenic and acetogenic, hydrogenogenic metabolism. The advantage of having different metabolic capabilities is that it raises the chance of survival in environments when electron acceptors become depleted. In marine sediments, SRB and methanogens do not compete but rather complement each other in the degradation of organic matter.Also in freshwater ecosystems with sulfate concentrations of only 10-200 μM, sulfate is consumed efficiently within the top several cm of the sediments. Here, many of the δ-Proteobacteria present have the genetic machinery to perform dissimilatory sulfate reduction, yet they have an acetogenic, hydrogenogenic way of life.In this review we evaluate the physiology and metabolic mode of SRB in relation with their environment.

  10. Melatonin: functions and ligands.

    Science.gov (United States)

    Singh, Mahaveer; Jadhav, Hemant R

    2014-09-01

    Melatonin is a chronobiotic substance that acts as synchronizer by stabilizing bodily rhythms. Its synthesis occurs in various locations throughout the body, including the pineal gland, skin, lymphocytes and gastrointestinal tract (GIT). Its synthesis and secretion is controlled by light and dark conditions, whereby light decreases and darkness increases its production. Thus, melatonin is also known as the 'hormone of darkness'. Melatonin and analogs that bind to the melatonin receptors are important because of their role in the management of depression, insomnia, epilepsy, Alzheimer's disease (AD), diabetes, obesity, alopecia, migraine, cancer, and immune and cardiac disorders. In this review, we discuss the mechanism of action of melatonin in these disorders, which could aid in the design of novel melatonin receptor ligands.

  11. Combinatorial expression patterns of heparan sulfate sulfotransferases in zebrafish: I. The 3-O-sulfotransferase family.

    Science.gov (United States)

    Cadwallader, Adam B; Yost, H Joseph

    2006-12-01

    Heparan sulfate (HS) is an unbranched chain of repetitive disaccharides, which specifically binds ligands when attached to the cell surface or secreted extracellularly. HS chains contain sulfated domains termed the HS fine structure, which gives HS specific binding affinities for extracellular ligands. HS 3-O-sulfotransferases (3-OST) catalyze the transfer of sulfate groups to the 3-O position of glucosamine residues of HS, a rare, but essential HS chain modification required for HS fine structure. We report here the first characterization and developmental expression analysis of the 3-OST gene family in a vertebrate. There are eight 3-OST genes in zebrafish: seven genes with homology to known 3-OST genes in mouse and human, as well as a novel, 3-OST-7. A phylogenetic comparison of human, mouse, and zebrafish indicates the 3-OST family can be subdivided into two distinct subgroups. We examined the mRNA expression patterns in several tissues/organs throughout early zebrafish development, including early cleavage stages, somites, brain, internal body organ primordial, and pectoral fin development. The 3-OST gene family has both specifically expressed and ubiquitously expressed genes, suggesting in vivo functional differences exist between members of this family.

  12. Tropolone as anionic and neutral ligand in lead(II) and bismuth(III) complexes: Synthesis, structure, characterization and computational studies

    Science.gov (United States)

    Lyczko, Krzysztof

    2017-01-01

    Two new metal complexes, [Bi(trop)2(Htrop)(CF3SO3)] (1) and [Pb(trop)2(Htrop)] (2), have been synthesized by reaction of the respective metal triflates with an excess of tropolone (Htrop) in the concentrated methanol or dimethylsulfoxide solution. In addition, it was found that complex 1 crystallizes through the formation of unstable intermediate methanol solvated tris(tropolonato)bismuth(III) compound. The characteristic behavior of tropolone which coordinates both as the bidentate anion (trop-) and the monodentate neutral molecule (Htrop) has been revealed in 1 and 2. The crystal structures of studied compounds have been determined by single-crystal X-ray diffraction. The molecular structures of both complexes have been compared with their geometries received from DFT calculations giving a good correlation. The presented compounds show coordination number of metal ion equal to five in 2 and six in 1 and the presence of stereochemically active 6s2 lone electron pair. The complexes were characterized by FT-IR, NMR and UV-Vis techniques. IR and UV-Vis spectra of 1 and 2 were also simulated by DFT methods. TD-DFT predictions demonstrate the frontier HOMOs and LUMOs cover in the major part the tropolonate and(or) tropolone moieties which gives mainly ligand-to-ligand charge transfer (LLCT) and ligand centered (LC) character to the energy bands above 300 nm.

  13. Template Synthesis, Characterization and Biological Activity of Cu(II, Ni(II, Co(II, Zn(IIComplexes with Isonicotinoylhydrazone--2-aldehydefluorene Ligand

    Directory of Open Access Journals (Sweden)

    2010-01-01

    Full Text Available This is about synthesizing new complex combinations of Cu(II, Ni(II,Co(II, Zn(II with aroylhydrazone ligand isonicotinoylhydrazone-2-aldehydefluorene (INHAF made by condensation of isonicotinoylhydrazine with 2-aldehydefluorene. The complexes have been characterized by analytical data, IR, UV-Vis, NMR spectra, magnetic susceptibility values, thermal analysis and for the Cu(II complex the ESR spectrum has been registered. For all complexes the biological activity against the Staphylo-coccus aureus, Escherichia coli, Klebssiella pneumoniae bacteria has been investigated. The experimental data sustain stoichiometry of 1:2 (metal/ligand for the Cu(II, Ni(II, Zn(II complexes and of 1:1 for the complex with Co(II. The electronic spectra and the magnetic moments suggest octahedral stereochemistry at the complexes with Cu(II, Ni(II and the tetrahedral geometry for the Co(II complex. The INHAF ligand is coordinated bidentate by the O=C amide oxygen and the azomethine nitrogen in the complexes of Cu(II, Ni(II, Co(II and monodentate by the azomethine nitrogen in the complex of Zn(II.

  14. Further Insight into the Lability of MeCN Ligands of Cytotoxic Cycloruthenated Compounds: Evidence for the Antisymbiotic Effect Trans to the Carbon Atom at the Ru Center.

    Science.gov (United States)

    Barbosa, Ana Soraya Lima; Werlé, Christophe; Colunga, Claudia Olivia Oliva; Rodríguez, Cecilia Franco; Toscano, Ruben Alfredo; Le Lagadec, Ronan; Pfeffer, Michel

    2015-08-03

    The two MeCN ligands in [Ru(2-C6H4-2'-Py-κC,N)(Phen, trans-C)(MeCN)2]PF6 (1), both trans to a sp(2) hybridized N atom, cannot be substituted by any other ligand. In contrast, the isomerized derivative [Ru(2-C6H4-2'-Py-κC,N)(Phen, cis-C)(MeCN)2]PF6 (2), in which one MeCN ligand is now trans to the C atom of the phenyl ring orthometalated to Ru, leads to fast and quantitative substitution reactions with several monodentate ligands. With PPh3, 2 affords [Ru(2-C6H4-2'-Py-κC,N)(Phen, cis-C)(PPh3)(MeCN)]PF6 (3), in which PPh3 is trans to the C σ bound to Ru. Compound 3 is not kinetically stable, because, under thermodynamic control, it leads to 4, in which the PPh3 is trans to a N atom of the Phen ligand. Dimethylsulfoxide (DMSO) can also substitute a MeCN ligand in 2, leading to 5, in which DMSO is coordinated to Ru via its S atom trans to the N atom of the Phen ligand, the isomer under thermodynamic control being the only compound observed. We also found evidence for the fast to very fast substitution of MeCN in 2 by water or a chloride anion by studying the electronic spectra of 2 in the presence of water or NBu4Cl, respectively. An isomerization related to that observed between 3 and 4 is also found for the known monophosphine derivative [Ru(2-C6H4-2'-Py-κC,N)(PPh3, trans-C)(MeCN)3]PF6 (10), in which the PPh3 is located trans to the C of the cyclometalated 2-phenylpyridine, since, upon treatment by refluxing MeCN, it leads to its isomer 11, [Ru(2-C6H4-2'-Py-κC,N)(PPh3, cis-C)(MeCN)3]PF6. Further substitutions are also observed on 11, whereby N^N chelates (N^N = 2,2'-bipyridine and phenanthroline) substitute two MeCN ligands, affording [Ru(2-C6H4-2'-Py-κC,N)(PPh3, cis-C)(N^N)(MeCN)]PF6 (12a and 12b). Altogether, the behavior of the obtained complexes by ligand substitution reactions can be rationalized by an antisymbiotic effect on the Ru center, trans to the C atom of the cyclometalated unit, leading to compounds having the least nucleophilic ligand trans to C

  15. Macrocyclic G-quadruplex ligands

    DEFF Research Database (Denmark)

    Nielsen, M C; Ulven, Trond

    2010-01-01

    G-quadruplex stabilizing compounds have recently received increased interest due to their potential application as anticancer therapeutics. A significant number of structurally diverse G-quadruplex ligands have been developed. Some of the most potent and selective ligands currently known are macr...

  16. Molecular docking of heparin oligosaccharides with Hep-II heparin-binding domain of fibronectin reveals an interplay between the different positions of sulfate groups.

    Science.gov (United States)

    Carpentier, Mathieu; Denys, Agnès; Allain, Fabrice; Vergoten, Gérard

    2014-02-01

    Fibronectin is a major component of the extracellular matrix and serves as support for cell adhesion and migration. Heparin and heparan sulfates (HS) have been reported to be high-affinity ligands for fibronectin. The strongest heparin/HS-binding site, named Hep-II, is located in the C-terminal repeat units FN12-14 of fibronectin. Mutational studies of recombinant fibronectin fragments and elucidation of the X-ray crystallographic structure of Hep-II in complex with heparin allowed localizing the main heparin/HS-binding site in FN13 to two parallel amino acid clusters: R1697, R1698, R1700 and R1714, R1716, R1745. Heparin, which is more sulfated than HS, is a better ligand for fibronectin, indicating that the sulfate density is important for the interactions. However, other studies demonstrated that the position of sulfate groups is also critical for high-affinity binding of the polysaccharides to fibronectin. In the current work, we used molecular docking of Hep-II domain of fibronectin with a series of differently sulfated dodecasaccharides of heparin to determine the implication of each sulfate position in the interaction. By using this approach, we confirmed the implication of R1697, R1698, R1700 and R1714 and we identified other amino acids possibly involved in the interaction. We also confirmed a hierarchic involvement of sulfate position as follows: 2S > 6S > NS. Interestingly, the formation of stable complexes required a mutual adaptation between Hep-II domain and oligosaccharides, which was different according to the pattern of sulfation. Finally, we demonstrated that 3-O-sulfation of heparin stabilized even more the complex with Hep-II by creating new molecular interactions. Collectively, our models point out the complexity of the molecular interactions between heparin/HS and fibronectin.

  17. Photochemistry of RuII 4,4′-Bi-1,2,3-triazolyl (btz) Complexes: Crystallographic Characterization of the Photoreactive Ligand-Loss Intermediate trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+

    OpenAIRE

    Welby, Christine E.; Armitage, Georgina K.; Bartley, Harry; Wilkinson, Aaron; Sinopoli, Alessandro; Uppal, Baljinder S; Rice, Craig R.; Elliott, Paul I.

    2014-01-01

    We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+ (1 a) that contains a monodentate chelate ligand. This and analogous complexes can be observed during the photolysis reactions of a family of complexes of the form [Ru(equation image)(btz)2]2+ (1 a–d: btz=1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl; equation image=a) 2,2′-bipyridyl (bpy), b) 4,4′-dimethyl-2,2′-...

  18. Optimization of a biological sulfate reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Lebel, A.

    1985-01-01

    A biological sulfate reduction process is presented. It is intended to treat sulfate wastes by converting them to hydrogen sulfide which can be further oxidized to elemental sulfur. An optimization study of a completely-mixed reactor system was performed. Major operating parameters were determined at the bench-scale level. The study was conducted in batch-culture experiments, using a mixed Desulfovibrio culture from sewage. Kinetic values were extrapolated using the Michaelis-Menten model, which best fitted the experimental data. The iron loading and the sulfate loading significantly affected the growth and metabolism of sulfate reducing bacteria (SRB). A model to determine V/sub m/ from the iron and sulfate loading values was explored. The model is limited by sulfate loading greater than 4.3 g/l, where bacterial growth is inhibited. Iron loading is not anticipated to suppress the bacterial metabolism efficiency since it remained in the linear pattern even at inhibition levels. Studies of the metabolic behavior of SRB, using lactic acid as the carbon source, showed a requirement of 2.7 moles of lactate for each mole of sulfate. This technique and its application to the sulfur recovery process are discussed.

  19. Cellular adhesion responses to the heparin-binding (HepII) domain of fibronectin require heparan sulfate with specific properties

    DEFF Research Database (Denmark)

    Mahalingam, Yashithra; Gallagher, John T; Couchman, John R

    2006-01-01

    Cell surface heparan sulfate (HS) proteoglycans are required in development and postnatal repair. Important classes of ligands for HS include growth factors and extracellular matrix macromolecules. For example, the focal adhesion component syndecan-4 interacts with the III(12-14) region of fibron......Cell surface heparan sulfate (HS) proteoglycans are required in development and postnatal repair. Important classes of ligands for HS include growth factors and extracellular matrix macromolecules. For example, the focal adhesion component syndecan-4 interacts with the III(12-14) region...... trap mutation in one of the two major glucosaminoglycan polymerases (EXT1). Several separate, specific properties of cell surface HS are therefore required in cell adhesion responses to the fibronectin HepII domain....

  20. Using Terrestrial Sulfate Efflorescences as an Analogue of Hydrated Sulfate Formation in Valles Marineris on Mars

    Science.gov (United States)

    Smith, P. C.; Szynkiewicz, A.

    2015-12-01

    Hydrated sulfate minerals provide conclusive evidence that a hydrologic cycle was once active on the surface of Mars. Two classes of hydrated sulfate minerals have been detected by robotic instruments on Mars: monohydrated sulfate minerals comprised of kieserite and gypsum, and various polyhydrated sulfates with Fe-Ca-Na-Mg-rich compositions. These minerals are found in various locations on Mars, including large surface exposures in valley settings of Valles Marineris. However, the sulfate sources and formation mechanisms of these minerals are not yet well understood.Recently, it has been suggested that the sulfate minerals in Valles Marineris might have formed in a manner similar to sulfate efflorescences found in dry environments on Earth. In this study, we use sulfate effloresences from the Rio Puerco Watershed, New Mexico as a terrestrial analogue to assess major factors that might have led to deposition of sulfate minerals in Valles Marineris. In different seasons indicative of dry and wet conditions, we collected field photographs and sediment samples for chemical and stable isotopic analyses (sulfur content, δ34S) to determine major sources of sulfate ions for efflorescences and to assess how the seasonal changes in surface/groundwater activity affect their formation. Preliminary sulfur isotope results suggest that oxidation of bedrock sulfides (0.01-0.05 wt. S %) is a major source of sulfate ion for efflorescences formation because their δ34S varied in negative range (-28 to -20‰) similar to sulfides (average -32‰). Using field photographs collected in Oct 2006, Feb and Nov 2012, May 2013, Mar and Oct 2014, we infer that the highest surface accumulation of sulfate efflorescences in the studied analog site was observed after summer monsoon seasons when more water was available for surface and subsurface transport of solutes from chemical weathering. Conversely, spring snow melt led to enhanced dissolution of sulfate efflorescences.

  1. The role of sulfate in aerobic granular sludge process for emerging sulfate-laden wastewater treatment.

    Science.gov (United States)

    Xue, Weiqi; Hao, Tianwei; Mackey, Hamish R; Li, Xiling; Chan, Richard C; Chen, Guanghao

    2017-11-01

    Sulfate-rich wastewaters pose a major threat to mainstream wastewater treatment due to the unpreventable production of sulfide and associated shift in functional bacteria. Aerobic granular sludge could mitigate these challenges in view of its high tolerance and resilience against changes in various environmental conditions. This study aims to confirm the feasibility of aerobic granular sludge in the treatment of sulfate containing wastewater, investigate the impact of sulfate on nutrient removal and granulation, and reveal metabolic relationships in the above processes. Experiments were conducted using five sequencing batch reactors with different sulfate concentrations operated under alternating anoxic/aerobic condition. Results showed that effect of sulfate on chemical oxygen demand (COD) removal is negligible, while phosphate removal was enhanced from 12% to 87% with an increase in sulfate from 0 to 200 mg/L. However, a long acclimatization of the biomass (more than 70 days) is needed at a sulfate concentration of 500 mg/L and a total deterioration of phosphate removal at 1000 mg/L. Batch tests revealed that sulfide promoted volatile fatty acids (VFAs) uptake, producing more energy for phosphate uptake when sulfate concentrations were beneath 200 mg/L. However, sulfide detoxification became energy dominating, leaving insufficient energy for Polyhydroxyalkanoate (PHA) synthesis and phosphate uptake when sulfate content was further increased. Granulation accelerated with increasing sulfate levels by enhanced production of N-Acyl homoserine lactones (AHLs), a kind of quorum sensing (QS) auto-inducer, using S-Adenosyl Methionine (SAM) as primer. The current study demonstrates interactions among sulfate metabolism, nutrients removal and granulation, and confirms the feasibility of using the aerobic granular sludge process for sulfate-laden wastewaters treatment with low to medium sulfate content. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Di-sulfated Keratan Sulfate as a Novel Biomarker for Mucopolysaccharidosis II, IVA, and IVB.

    Science.gov (United States)

    Shimada, Tsutomu; Tomatsu, Shunji; Mason, Robert W; Yasuda, Eriko; Mackenzie, William G; Hossain, Jobayer; Shibata, Yuniko; Montaño, Adriana M; Kubaski, Francyne; Giugliani, Roberto; Yamaguchi, Seiji; Suzuki, Yasuyuki; Orii, Kenji E; Fukao, Toshiyuki; Orii, Tadao

    2015-01-01

    Keratan sulfate (KS) is a storage material in mucopolysaccharidosis IV (MPS IV). However, no detailed analysis has been reported on subclasses of KS: mono-sulfated KS and di-sulfated KS. We established a novel method to distinguish and quantify mono- and di-sulfated KS using liquid chromatography-tandem mass spectrometry and measured both KS levels in various specimens.Di-sulfated KS was dominant in shark cartilage and rat serum, while mono-sulfated KS was dominant in bovine cornea and human serum. Levels of both mono- and di-sulfated KS varied with age in the blood and urine from control subjects and patients with MPS II and IVA. The mean levels of both forms of KS in the plasma/serum from patients with MPS II, IVA, and IVB were elevated compared with that in age-matched controls. Di-sulfated KS provided more significant difference between MPS IVA and the age-matched controls than mono-sulfated KS. The ratio of di-sulfated KS to total KS in plasma/serum increased with age in control subjects and patients with MPS II but was age independent in MPS IVA patients. Consequently, this ratio can discriminate younger MPS IVA patients from controls. Levels of mono- and di-sulfated KS in urine of MPS IVA and IVB patients were all higher than age-matched controls for all ages studied.In conclusion, the level of di-sulfated KS and its ratio to total KS can distinguish control subjects from patients with MPS II, IVA, and IVB, indicating that di-sulfated KS may be a novel biomarker for these disorders.

  3. Analysis of tyrosine-O-sulfation

    DEFF Research Database (Denmark)

    Bundgaard, J.R.; Sen, J.W.; Johnsen, A.H.

    2008-01-01

    Tyrosine O-sulfation was first described about 50 years ago as a post-translational modification of fibrinogen. In the following 30 years it was considered to be a rare modification affecting only a few proteins and peptides. However, in the beginning of the 1980s tyrosine (Tyr) sulfation was shown...... the presence of radioactively labeled tyrosine. These techniques have been described in detail previously. The aim of this chapter is to present alternative analytical methods of Tyr sulfation than radioisotope incorporation before analysis Udgivelsesdato: 2008...

  4. Sulfated binary and trinary oxide solid superacids

    Institute of Scientific and Technical Information of China (English)

    缪长喜; 华伟明; 陈建民; 高滋

    1996-01-01

    A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides into ZrO2 may produce a positive or negative effect on the acid strength and catalytic activity of the solid superacids. Sulfated oxides of Cr-Zr, Fe-Cr-Zr and Fe-V-Zr are 2 - 3 times more active than the reported sulfated Fe-Mn-Zr oxide. The enhancement in the superacidity and catalytic activity of these new solid superacids has been discussed on account of the results of various characteriation techniques.

  5. Chlorate: a reversible inhibitor of proteoglycan sulfation

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, D.E.; Silbert, J.E.

    1988-07-15

    Bovine aorta endothelial cells were cultured in medium containing (/sup 3/H)glucosamine, (/sup 35/S)sulfate, and various concentrations of chlorate. Cell growth was not affected by 10 mM chlorate, while 30 mM chlorate had a slight inhibitory effect. Chlorate concentrations greater than 10 mM resulted in significant undersulfation of chondroitin. With 30 mM chlorate, sulfation of chondroitin was reduced to 10% and heparan to 35% of controls, but (/sup 3/H)glucosamine incorporation on a per cell basis did not appear to be inhibited. Removal of chlorate from the culture medium of cells resulted in the rapid resumption of sulfation.

  6. Mass Spectrometry Combinations for Structural Characterization of Sulfated-Steroid Metabolites

    Science.gov (United States)

    Yan, Yuetian; Rempel, Don L.; Holy, Timothy E.; Gross, Michael L.

    2014-05-01

    Steroid conjugates, which often occur as metabolites, are challenging to characterize. One application is female-mouse urine, where steroid conjugates serve as important ligands for the pheromone-sensing neurons. Although the two with the highest abundance in mouse urine were previously characterized with mass spectrometry (MS) and NMR to be sulfated steroids, many more exist but remain structurally unresolved. Given that their physical and chemical properties are similar, they are likely to have a sulfated steroid ring structure. Because these compounds occur in trace amounts in mouse urine and elsewhere, their characterization by NMR will be difficult. Thus, MS methods become the primary approach for determining structure. Here, we show that a combination of MS tools is effective for determining the structures of sulfated steroids. Using 4-pregnene analogs, we explored high-resolving power MS (HR-MS) to determine chemical formulae; HD exchange MS (HDX-MS) to determine number of active, exchangeable hydrogens (e.g., OH groups); methoxyamine hydrochloride (MOX) derivatization MS, or reactive desorption electrospray ionization with hydroxylamine to determine the number of carbonyl groups; and tandem MS (MSn), high-resolution tandem MS (HRMS/MS), and GC-MS to obtain structural details of the steroid ring. From the fragmentation studies, we deduced three major fragmentation rules for this class of sulfated steroids. We also show that a combined MS approach is effective for determining structure of steroid metabolites, with important implications for targeted metabolomics in general and for the study of mouse social communication in particular.

  7. Glutamate receptor ligands

    DEFF Research Database (Denmark)

    Guldbrandt, Mette; Johansen, Tommy N; Frydenvang, Karla Andrea;

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA......-ray crystallographic analyses, chemical correlation, and CD spectral analyses. The effects of the individual stereoisomers at ionotropic and metabotropic (S)-Glu receptors (iGluRs and mGluRs) were characterized. Compounds with S-configuration at the alpha-carbon generally showed mGluR2 agonist activity of similar...... limited effect on pharmacology. Structure-activity relationships at iGluRs in the rat cortical wedge preparation showed a complex pattern, some compounds being NMDA receptor agonists [e.g., EC(50) =110 microM for (2S,5RS)-5-methyl-AA (6a,b)] and some compounds showing NMDA receptor antagonist effects [e...

  8. Sulfated polysaccharides identified as inducers of neuropilin-1 internalization and functional inhibition of VEGF165 and semaphorin3A

    Science.gov (United States)

    Narazaki, Masashi; Segarra, Marta

    2008-01-01

    Neuropilin-1 (NRP1) and NRP2 are cell surface receptors shared by class 3 semaphorins and vascular endothelial growth factor (VEGF). Ligand interaction with NRPs selects the specific signal transducer, plexins for semaphorins or VEGF receptors for VEGF, and promotes NRP internalization, which effectively shuts down receptor-mediated signaling by a second ligand. Here, we show that the sulfated polysaccharides dextran sulfate and fucoidan, but not others, reduce endothelial cell-surface levels of NRP1, NRP2, and to a lesser extent VEGFR-1 and VEGFR-2, and block the binding and in vitro function of semaphorin3A and VEGF165. Administration of fucoidan to mice reduces VEGF165-induced angiogenesis and tumor neovascularization in vivo. We find that dextran sulfate and fucoidan can bridge the extracellular domain of NRP1 to that of the scavenger receptor expressed by endothelial cells I (SREC-I), and induce NRP1 and SREC-I coordinate internalization and trafficking to the lysosomes. Overexpression of SREC-I in SREC-I–negative cells specifically reduces cell-surface levels of NRP1, indicating that SREC-I mediates NRP1 internalization. These results demonstrate that engineered receptor internalization is an effective strategy for reducing levels and function of cell-surface receptors, and identify certain sulfated polysaccharides as “internalization inducers.” PMID:18272814

  9. Sulfated cellulose thin films with antithrombin affinity

    Directory of Open Access Journals (Sweden)

    2009-11-01

    Full Text Available Cellulose thin films were chemically modified by in situ sulfation to produce surfaces with anticoagulant characteristics. Two celluloses differing in their degree of polymerization (DP: CEL I (DP 215–240 and CEL II (DP 1300–1400 were tethered to maleic anhydride copolymer (MA layers and subsequently exposed to SO3•NMe3 solutions at elevated temperature. The impact of the resulting sulfation on the physicochemical properties of the cellulose films was investigated with respect to film thickness, atomic composition, wettability and roughness. The sulfation was optimized to gain a maximal surface concentration of sulfate groups. The scavenging of antithrombin (AT by the surfaces was determined to conclude on their potential anticoagulant properties.

  10. ROE Wet Sulfate Deposition 2009-2011

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2009 to 2011. Summary data in this indicator were provided by EPA’s...

  11. Sulfate reduction and methanogenesis at a freshwater

    DEFF Research Database (Denmark)

    Iversen, Vibeke Margrethe Nyvang; Andersen, Martin Søgaard; Jakobsen, Rasmus

    The freshwater-seawater interface was studied in a ~9-m thick anaerobic aquifer located in marine sand and gravel with thin peat lenses. Very limited amounts of iron-oxides are present. Consequently, the dominating redox processes are sulfate reduction and methanogenesis, and the groundwater...... is enriched in dissolved sulfide, methane and bicarbonate. Under normal conditions the seawater-freshwater interface is found at a depth of 4 m at the coastline and reaches the bottom of the aquifer 40 m inland. However, occasional flooding of the area occurs, introducing sulfate to the aquifer. Groundwater...... chemistry was studied in a 120 m transect perpendicular to the coast. Cores were taken for radiotracer rate measurements of sulfate reduction and methanogenesis. In the saline part of the aquifer 35 m inland, sulfate reduction was the dominant process with rates of 0.1-10 mM/year. In the freshwater part 100...

  12. Sulfate reduction and methanogenesis at a freshwater

    DEFF Research Database (Denmark)

    Iversen, Vibeke Margrethe Nyvang; Andersen, Martin Søgaard; Jakobsen, Rasmus

    The freshwater-seawater interface was studied in a ~9-m thick anaerobic aquifer located in marine sand and gravel with thin peat lenses. Very limited amounts of iron-oxides are present. Consequently, the dominating redox processes are sulfate reduction and methanogenesis, and the groundwater...... is enriched in dissolved sulfide, methane and bicarbonate. Under normal conditions the seawater-freshwater interface is found at a depth of 4 m at the coastline and reaches the bottom of the aquifer 40 m inland. However, occasional flooding of the area occurs, introducing sulfate to the aquifer. Groundwater...... chemistry was studied in a 120 m transect perpendicular to the coast. Cores were taken for radiotracer rate measurements of sulfate reduction and methanogenesis. In the saline part of the aquifer 35 m inland, sulfate reduction was the dominant process with rates of 0.1-10 mM/year. In the freshwater part 100...

  13. Sulfate Resistance of Alkali Activated Pozzolans

    OpenAIRE

    Bondar, Dali

    2015-01-01

    The consequence of sulfate attack on geopolymer concrete, made from an alkali activated natural pozzolan (AANP) has been studied in this paper. Changes in the compressive strength, expansion and capillary water absorption of specimens have been investigated combined with phases determination by means of X-ray diffraction. At the end of present investigation which was to evaluate the performance of natural alumina silica based geopolymer concrete in sodium and magnesium sulfate solution, the l...

  14. Is there a correlation between structure and anticoagulant action of sulfated galactans and sulfated fucans?

    Science.gov (United States)

    Pereira, Mariana S; Melo, Fábio R; Mourão, Paulo A S

    2002-10-01

    We attempted to identify the specific structural features in sulfated galactans and sulfated fucans that confer anticoagulant activity. For this study we employed a variety of invertebrate polysaccharides with simple structures composed of well-defined units of oligosaccharides. Our results indicate that a 2-O-sulfated, 3-linked alpha-L-galactan, but not a alpha-L-fucan with a similar molecular size, is a potent thrombin inhibitor mediated by antithrombin or heparin cofactor II. The difference between the activities of these two polysaccharides is not very pronounced when factor Xa replaced thrombin. The occurrence of 2,4-di-O-sulfated units is an amplifying motif for 3-linked alpha-fucan-enhanced thrombin inhibition by antithrombin. If we replace antithrombin by heparin cofactor II, then the major structural requirement for the activity becomes single 4-O-sulfated fucose units. The presence of 2-O-sulfated fucose residues always had a deleterious effect on anticoagulant activity. Overall, our results indicate that the structural requirements for interaction of sulfated galactans and sulfated fucans with coagulation cofactors and their target proteases are stereospecific and not merely a consequence of their charge density and sulfate content.

  15. Hormonal control of sulfate uptake and assimilation.

    Science.gov (United States)

    Koprivova, Anna; Kopriva, Stanislav

    2016-08-01

    Plant hormones have a plethora of functions in control of plant development, stress response, and primary metabolism, including nutrient homeostasis. In the plant nutrition, the interplay of hormones with responses to nitrate and phosphate deficiency is well described, but relatively little is known about the interaction between phytohormones and regulation of sulfur metabolism. As for other nutrients, sulfate deficiency results in modulation of root architecture, where hormones are expected to play an important role. Accordingly, sulfate deficiency induces genes involved in metabolism of tryptophane and auxin. Also jasmonate biosynthesis is induced, pointing to the need of increase the defense capabilities of the plants when sulfur is limiting. However, hormones affect also sulfate uptake and assimilation. The pathway is coordinately induced by jasmonate and the key enzyme, adenosine 5'-phosphosulfate reductase, is additionally regulated by ethylene, abscisic acid, nitric oxid, and other phytohormones. Perhaps the most intriguing link between hormones and sulfate assimilation is the fact that the main regulator of the response to sulfate starvation, SULFATE LIMITATION1 (SLIM1) belongs to the family of ethylene related transcription factors. We will review the current knowledge of interplay between phytohormones and control of sulfur metabolism and discuss the main open questions.

  16. Ammonium sulfate preparation from phosphogypsum waste

    Directory of Open Access Journals (Sweden)

    Abdel-Hakim T. Kandil

    2017-01-01

    Full Text Available The Egyptian phosphogypsum waste is treated using sulfuric acid prior the ammonium sulfate production. The relevant factors that would affect the removal efficiencies of some impurities are studied. The optimum conditions of the treatment are 8 M sulfuric acid solution and 1/4 solid/liquid ratio for 30 min contact time at 80 °C. Moreover, the optimum conditions of the ammonium sulfate preparation are 10 g of the suspended impure or purified phosphogypsum in 40 ml of 3% ammonium sulfate solution (as initiator, 1/4 solid/liquid ratio at pH7 at an addition of an excess ammonium carbonate, and 150 rpm stirring speed for 4.0 h contact time at 55 °C as well as the 5 mg of barium chloride is added to remove the radium in the ammonium sulfate product. Finally, the ammonium sulfate is crystallized and the chemical analysis of the product shows 20% nitrogen and 23.6% sulfur. Therefore, the purity of the obtained ammonium sulfate is 95% from the purified phosphogypsum.

  17. Preparation of Agarose Sulfate and Its Antithrombogenicity

    Institute of Scientific and Technical Information of China (English)

    JIE Youping; ZHANG Lingmin; CHEN Peng; MAO Xuan; TANG Shunqing

    2012-01-01

    As one of the seaweed polysaccharide,agarose has received much attention because of its biocompatibility.However,its application in biomedical field was limited with its biological inertia.Modification with some functional groups is needed to obtain agarose derivatives with biological activity and expand its applications.Consequently,agarose was sulfated with chlorosulfonic acid-pyridine with formamide as dispersing agent.The orthogonal test result showed that the optimal reaction condition was the reaction time being 4 h,the reaction temperature 65 ℃,and the ratio of chlorosulfonic acid to agarose 1-4(mL/g).Two kinds of the insoluble agarose sulfate (below 37 ℃) were synthesized with degree of substitution (DS) being 0.17 and 0.43 respectively.Infrared spectroscopy (IR) and 13C nuclear magnetic resonance (13C-NMR) spectroscopy results proved that C3-6 in agarose was sulfated.Their hydrophobic property and BSA adsorption capacity rose with increasing DS,while the adsorption of Hb was reduced.The anti-clotting properties of agarose sulfate were significantly improved,and agarose sulfate could protect red blood cells from deformation after adsorption of BSA.These findings demonstrate that the cold-water insoluble agarose sulfate has a promise for applications as heparin-like material in anticoagulation or endothelial regeneration scaffold.

  18. Structure of a rat hepatoma heparan sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Fedarko, N.S.; Ishihara, M.; Conrad, H.E.

    1986-05-01

    Previous studies showed that as monolayer cultures of a rat hepatocyte cell line passed from log growth to confluency there was an increase in sulfation of heparan sulfate (HS) and the accumulation of a unique species of HS with a high content of sulfated GlcA residues in the nucleus. The present study compares the HS metabolism of a rat (Morris) hepatoma line. Cells were labeled with /sup 35/SO/sub 4//sup 2 -/ and the structure and distribution of (/sup 35/SO/sub 4/)HS from the culture medium (CM), the pericellular matrix (Ma), the nucleus (NUC), the outer nuclear membrane (NM), and the remaining cytoplasmic (CP) pool was measured as nitrous acid-susceptible material. The amount of label incorporated into each pool was 1/10 that observed in the hepatocyte line. The HS proteglycan and the free HS chains from the hepatoma showed size distributions similar to those found for the hepatocytes, but a lower average charge density. In the HS from the CM, Ma, and CP pools 56% of glucosamine residues were sulfated; in that from the NM and NUC pools 46% were sulfated. HONO treatment gave mono- and disulfated disaccharides in a ratio of 1.5:1 for all five cellular pools, but showed that the HS from the NUC pool did not contain high levels of sulfated GlcA residues.

  19. Sulfated polysaccharides and cell differentiation in the sea urchin embryo.

    Science.gov (United States)

    Løvtrup-Rein, H; Løvtrup, S

    1984-01-01

    The synthesis of sulfated polysaccharides during the embryonic development of Paracentrotus lividus has been investigated by incorporation of radioactive sulfate, glucose, glucosamine and fucose. The following substances become labelled: fucan sulfate (approximately 60%), heparan sulfate (approximately 20%) and dermatan sulfate (approximately 20%), and possibly a very slight amount of chondroitin sulfate. In animalized and vegetalized embryos, the rate of incorporation is significantly reduced, and furthermore dermatan sulfate is almost absent in animalized embryos. It is concluded that this substance is associated with the differentiation of vegetative cells, possibly the mesenchyme cells.

  20. Synthesis, structure, fluorescent property, and antibacterial activity of new Cd(II) metal complex based on multidentate Schiff base ligand N,N‧-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane

    Science.gov (United States)

    Majumdar, Dhrubajyoti; Das, Sourav; Biswas, Jayanta Kumar; Mondal, Monojit

    2017-04-01

    The sequential reaction of a multisite coordinating compartmental ligand N,N‧-Bis(3-methoxysalicylidenimino)-1,3-diaminopropane (H2L1) with Cd(OAc)2 followed by the addition of NaCl in a 2:3:2 stoichiometric ratio affords homometallic trinuclear Cd(II) coordination compound [Cd3(L1)2(Cl)2] (1). The complex 1 has been thoroughly characterized by common elemental analysis (CHN), FT-IR and UV-Vis spectroscopy. Single crystal X-ray diffraction was also performed to determine the complete structure of complex 1. X-ray diffraction studies reveal that the molecular complex comprises a linear tri-nuclear ensemble of cadmium metal ions, which is further supported by the concerted coordination action of two dianionic [L1]2- ligands along with two monodentate Cl- ligands. The central Cd(II) ion is attached to the terminal Cd(II) ions through two phenoxide bridging groups of the fully deprotonated ligands [L1]2-. This arrangement leads to two neighbouring four membered Cd2O2 rings. The terminal Cd(II) ions are penta-coordinated (2 N, 2O, Cl) in a distorted square pyramidal geometry and central Cd(II) ion attained distorted trigonal prismatic geometry through six oxygen atoms coordination from ligands. Tri-nuclear Cd(II) complex 1 display intraligand (π-π∗) fluorescence in DMSO solution at room temperature. The fluorescence properties of complex 1 as well as the respective di-compartmental Schiff base ligand (H2L1) have been investigated in DMSO solvent at room temperature with a comparative approach. Result confirmed that complex 1 is highly fluorescence active mediated due to "chelation enhanced fluorescence" [CHEF] but Schiff base ligand (H2L1) is fluorescence silent. The antibacterial efficacy of complex 1 was further investigated against some important Gram-positive and Gram-negative bacteria.

  1. New Proton-Ionizable, Calixarene-Based Ligands for Selective Metal Ion Separations

    Energy Technology Data Exchange (ETDEWEB)

    Bartsch, Richard A.

    2012-06-04

    The project objective was the discovery of new ligands for performing metal ion separations. The research effort entailed the preparation of new metal ion complexing agents and polymers and their evaluation in metal ion separation processes of solvent extraction, synthetic liquid membrane transport, and sorption. Structural variations in acyclic, cyclic, and bicyclic organic ligands were used to probe their influence upon the efficiency and selectivity with which metal ion separations can be performed. A unifying feature of the ligand structures is the presence of one (or more) side arm with a pendent acidic function. When a metal ion is complexed within the central cavity of the ligand, ionization of the side arm(s) produces the requisite anion(s) for formation of an overall electroneutral complex. This markedly enhances extraction/transport efficiency for separations in which movement of aqueous phase anions of chloride, nitrate, or sulfate into an organic medium would be required. Through systematic structural variations, new ligands have been developed for efficient and selective separations of monovalent metal ions (e.g., alkali metal, silver, and thallium cations) and of divalent metal ion species (e.g., alkaline earth metal, lead, and mercury cations). Research results obtained in these fundamental investigations provide important insight for the design and development of ligands suitable for practical metal ion separation applications.

  2. Purification of papain by metal affinity partitioning in aqueous two-phase polyethylene glycol/sodium sulfate systems.

    Science.gov (United States)

    Jiang, Zhi-Guo; Zhang, Hai-De; Wang, Wei-Tao

    2015-05-01

    A simple and inexpensive aqueous two-phase affinity partitioning system using metal ligands was introduced to improve the selectivity of commercial papain extraction. Polyethylene glycol 4000 was first activated using epichlorohydrin, then it was covalently linked to iminodiacetic acid. Finally, the specific metal ligand Cu(2+) was attached to the polyethylene glycol-iminodiacetic acid. The chelated Cu(2+) content was measured by atomic absorption spectrometry as 0.88 mol/mol (polyethylene glycol). The effects on the purification at different conditions, including polyethylene glycol molecular weight (2000, 4000, and 6000), concentration of phase-forming components (polyethylene glycol 12-20% w/w and sodium sulfate 12-20%, w/w), metal ligand type, and concentration, system pH and the commercial papain loading on papain extraction, were systematically studied. Under optimum conditions of the system, i.e. 18% w/w sodium sulfate, 18% w/w polyethylene glycol 4000, 1% w/w polyethylene glycol-iminodiacetic acid-Cu(2+) and pH 7, a maximum yield of 90.3% and a degree of purification of 3.6-fold were obtained. Compared to aqueous two phase extraction without ligands, affinity partitioning was found to be an effective technique for the purification of commercial papain with higher extraction efficiency and degree of purification.

  3. Sulfated polysaccharides and immune response: promoter or inhibitor?

    Science.gov (United States)

    Chen, D; Wu, X Z; Wen, Z Y

    2008-06-01

    Sulfated polysaccharides, which frequently connect to core protein, are expressed not only on cell surface but also throughout the extracellular matrix. Besides providing structural integrity of cells, sulfated polysaccharides interact with a variety of sulfated polysaccharides-binding proteins, such as growth factors, cytokines, chemokines and proteases. Sulfated polysaccharides play two-edged roles, inhibitor and promoter, in immune response. Some sulfated polysaccharides act as the immunosuppressor by blocking inflammatory signal transduction induced by proinflammatory cytokines, suppressing the activation of complement and inhibiting the process that leukocytes adhere to and pass through endothelium. On the contrary, the interaction between immune cells and sulfated polysaccharides produced by bacteria, endothelial cells and immune cells initiate the occurrence of immune response. It promotes the processes of recognizing and arresting antigen, migrating transendothelium, moving into and out of immune organ and enhancing the proliferation of lymphocyte. The structure of sulfated polysaccharides, such as molecular weight and sulfated sites heterogeneity, especially the degree of disaccharide sulfation, position of the sulfate moiety and organization of sulfated domains, may play critical role in their controversial effects. As a consequence, the interaction between sulfated polysaccharides and sulfated polysaccharide-binding proteins may be changed by modifying the structure of sulfated polysaccharides chains. The administration of drug targeting sulfated polysaccharide-protein interaction may be useful in treating inflammatory related diseases.

  4. On the roles and regulation of chondroitin sulfate and heparan sulfate in zebrafish pharyngeal cartilage morphogenesis

    DEFF Research Database (Denmark)

    Holmborn, Katarina; Habicher, Judith; Kasza, Zsolt;

    2012-01-01

    The present study addresses the roles of heparan sulfate (HS) proteoglycans and chondroitin sulfate (CS) proteoglycans in the development of zebrafish pharyngeal cartilage structures. uxs1 and b3gat3 mutants, predicted to have impaired biosynthesis of both HS and CS because of defective formation...

  5. 21 CFR 524.960 - Flumethasone, neomycin sulfate, and polymyxin B sulfate ophthalmic solutions.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Flumethasone, neomycin sulfate, and polymyxin B sulfate ophthalmic solutions. 524.960 Section 524.960 Food and Drugs FOOD AND DRUG ADMINISTRATION... fundamental healing mechanism. Adrenocorticoid compounds have been reported to cause an increase in...

  6. Tyrosine sulfation of native mouse Psgl-1 is required for optimal leukocyte rolling on P-selectin in vivo.

    Directory of Open Access Journals (Sweden)

    Andrew D Westmuckett

    Full Text Available BACKGROUND: We recently demonstrated that tyrosine sulfation is an important contributor to monocyte recruitment and retention in a mouse model of atherosclerosis. P-selectin glycoprotein ligand-1 (Psgl-1 is tyrosine-sulfated in mouse monocyte/macrophages and its interaction with P-selectin is important in monocyte recruitment in atherosclerosis. However, whether tyrosine sulfation is required for the P-selectin binding function of mouse Psgl-1 is unknown. Here we test the function of native Psgl-1 expressed in leukocytes lacking endogenous tyrosylprotein sulfotransferase (TPST activity. METHODOLOGY/PRINCIPAL FINDINGS: Psgl-1 function was assessed by examining P-selectin dependent leukocyte rolling in post-capillary venules of C57BL6 mice transplanted with hematopoietic progenitors from wild type (WT → B6 or Tpst1;Tpst2 double knockout mice (Tpst DKO → B6 which lack TPST activity. We observed that rolling flux fractions were lower and leukocyte rolling velocities were higher in Tpst DKO → B6 venules compared to WT → B6 venules. Similar results were observed on immobilized P-selectin in vitro. Finally, Tpst DKO leukocytes bound less P-selectin than wild type leukocytes despite equivalent surface expression of Psgl-1. CONCLUSIONS/SIGNIFICANCE: These findings provide direct and convincing evidence that tyrosine sulfation is required for optimal function of mouse Psgl-1 in vivo and suggests that tyrosine sulfation of Psgl-1 contributes to the development of atherosclerosis.

  7. Modeling of sulfation of potassium chloride by ferric sulfate addition during grate-firing of biomass

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Aho, Martti

    2013-01-01

    Potassium chloride, KCl, formed from critical ash-forming elements released during combustion may lead to severe ash deposition and corrosion problems in biomass-fired boilers. Ferric sulfate, Fe2(SO4)3 is an effective additive, which produces sulfur oxides (SO2 and SO3) to convert KCl to the less...... harmful K2SO4. In the present study the decomposition of ferric sulfate is studied in a fast-heating rate thermogravimetric analyzer (TGA), and a kinetic model is proposed to describe the decomposition process. The yields of SO2 and SO3 from ferric sulfate decomposition are investigated in a laboratory......-scale tube reactor. It is revealed that approximately 40% of the sulfur is released as SO3, the remaining fraction being released as SO2. The proposed decomposition model of ferric sulfate is combined with a detailed gas phase kinetic model of KCl sulfation, and a simplified model of K2SO4 condensation...

  8. Heparin-like properties of sulfated alginates with defined sequences and sulfation degrees.

    Science.gov (United States)

    Arlov, Øystein; Aachmann, Finn Lillelund; Sundan, Anders; Espevik, Terje; Skjåk-Bræk, Gudmund

    2014-07-14

    Sulfated glycosaminoglycans have a vast range of protein interactions relevant to the development of new biomaterials and pharmaceuticals, but their characterization and application is complicated mainly due to a high structural variability and the relative difficulty to isolate large quantities of structurally homogeneous samples. Functional and versatile analogues of heparin/heparan sulfate can potentially be created from sulfated alginates, which offer structure customizability through targeted enzymatic epimerization and precise tuning of the sulfation degree. Alginates are linear polysaccharides consisting of β-D-mannuronic acid (M) and α-L-guluronic acid (G), derived from brown algae and certain bacteria. The M/G ratio and distribution of blocks are critical parameters for the physical properties of alginates and can be modified in vitro using mannuronic-C5-epimerases to introduce sequence patterns not found in nature. Alginates with homogeneous sequences (poly-M, poly-MG, and poly-G) and similar molecular weights were chemically sulfated and structurally characterized by the use of NMR and elemental analysis. These sulfated alginates were shown to bind and displace HGF from the surface of myeloma cells in a manner similar to heparin. We observed dependence on the sulfation degree (DS) as well as variation in efficacy based on the alginate monosaccharide sequence, relating to relative flexibility and charge density in the polysaccharide chains. Co-incubation with human plasma showed complement compatibility of the alginates and lowering of soluble terminal complement complex levels by sulfated alginates. The sulfated polyalternating (poly-MG) alginate proved to be the most reproducible in terms of precise sulfation degrees and showed the greatest relative degree of complement inhibition and HGF interaction, maintaining high activity at low DS values.

  9. Immunohistochemical localization of chondroitin sulfate, chondroitin sulfate proteoglycan, heparan sulfate proteoglycan, entactin, and laminin in basement membranes of postnatal developing and adult rat lungs

    DEFF Research Database (Denmark)

    Sannes, P L; Burch, K K; Khosla, J

    1993-01-01

    Histologic preparations of lungs from 1-, 5-, 10-, 18-, and 25-day-old postnatal and adult rats were examined immunohistochemically with antibodies specific against chondroitin sulfate (CS), basement membrane chondroitin sulfate proteoglycan (BM-CSPG), heparan sulfate proteoglycan (HSPG), entactin...

  10. Visualization of Metal-to-Ligand and Ligand-to-Ligand Charge Transfer in Metal-Ligand Complexes

    Institute of Scientific and Technical Information of China (English)

    Yong Ding; Jian-xiu Guo; Xiang-si Wang; Sha-sha Liu; Feng-cai Ma

    2009-01-01

    Three methods including the atomic resolved density of state, charge difference density, and the transition density matrix are used to visualize metal to ligand charge transfer (MLCT) in ruthenium(Ⅱ) ammine complex. The atomic resolved density of state shows that there is density of Ru on the HOMOs. All the density is localized on the ammine, which reveals that the excited electrons in the Ru complex are delocalized over the ammine ligand. The charge difference density shows that all the holes are localized on the Ru and the electrons on the ammine. The localization explains the MLCT on excitation. The transition density matrix shows that there is electron-hole coherence between Ru and ammine. These methods are also used to examine the MLCT in Os(bpy)(p0p)Cl ("Osp0p"; bpy=2,2'-bipyridyl; p0p=4,4'-bipyridyl) and the ligand-to-ligand charge transfer (LLCT) in Alq3. The calculated results show that these methods are powerful to examine MLCT and LLCT in the metal-ligand system.

  11. Monofunctional platinum(II) complexes with potent tumor cell growth inhibitory activity: the effect of a hydrogen-bond donor/acceptor N-heterocyclic ligand.

    Science.gov (United States)

    Margiotta, Nicola; Savino, Salvatore; Gandin, Valentina; Marzano, Christine; Natile, Giovanni

    2014-06-01

    In this paper we investigate the possibility of further increase the role of the N-donor aromatic base in antitumor Hollis-type compounds by conferring the possibility to act as a hydrogen-bond donor/acceptor. Therefore, we synthesized the Pt(II) complex cis-[PtCl(NH3 )2 (naph)]NO3 (1) containing the 1,8-naphthyridine (naph) ligand. The naphthyridine ligand is generally monodentate, and the second nitrogen atom can act as H-bond donor/acceptor depending upon its protonation state. The possibility of forming such an H-bond could be crucial in the interaction of the drug with DNA or proteins. Apart from the synthesis of the compound, in this study we evaluated its in vitro antitumor activity in a wide panel of tumor cell lines, also including cells selected for their sensitivity/resistance to oxaliplatin, which was compared with that of previously reported complex 2 ([PtI(2,9-dimethyl-1,10-phenanthroline)(1-methyl-cytosine)]I) and oxaliplatin and cisplatin as reference compounds. The cytotoxicity data were correlated with the cellular uptake and the DNA platination levels. Finally, the reactivity of 1 towards guanosine 5'-monophosphate (5'-GMP) and glutathione was investigated to provide insights into its mechanism of action.

  12. Crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand.

    Science.gov (United States)

    Kessler, Monty; Godemann, Christian; Spannenberg, Anke; Beweries, Torsten

    2016-12-01

    The crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand are reported, namely [di-methylbis-(η(5)-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κ(2)O,O')titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]·C7H8, 1, and chlorido-[di-methyl-bis-(η(5)-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κO)titanium(IV), [Ti(CF3O3S)(C20H30Si)Cl], 2. Both complexes display a bent metallocene unit, the metal atom being coordinated in a distorted tetra-hedral geometry, with the tri-fluoro-methane-sulfonate anion acting as a bidentate or monodentate ligand in 1 and 2, respectively. In 1, weak π-π stacking inter-actions involving the toluene solvent mol-ecules [centroid-to-centroid distance = 3.9491 (11) Å] are observed.

  13. Glycine zinc sulfate penta­hydrate: redetermination at 10 K from time-of-flight neutron Laue diffraction

    Science.gov (United States)

    Fortes, A. Dominic; Howard, Christopher M.; Wood, Ian G.; Gutmann, Matthias J.

    2016-01-01

    Single crystals of glycine zinc sulfate penta­hydrate [systematic name: hexa­aqua­zinc tetra­aquadiglycinezinc bis­(sulfate)], [Zn(H2O)6][Zn(C2H5NO2)2(H2O)4](SO4)2, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octa­hedra on sites of symmetry -1 and two SO4 tetra­hedra with site symmetry 1; the octa­hedra comprise one [tetra­aqua-diglycine zinc]2+ ion (centred on one Zn atom) and one [hexa­aqua­zinc]2+ ion (centred on the other Zn atom); the glycine zwitterion, NH3 +CH2COO−, adopts a monodentate coordination to the first Zn atom. All other atoms sit on general positions of site symmetry 1. Glycine forms centrosymmetric closed cyclic dimers due to N—H⋯O hydrogen bonds between the amine and carboxyl­ate groups of adjacent zwitterions and exhibits torsion angles varying from ideal planarity by no more than 1.2°, the smallest values for any known glycine zwitterion not otherwise constrained by a mirror plane. This work confirms the H-atom locations estimated in three earlier single-crystal X-ray diffraction studies with the addition of independently refined fractional coordinates and Uij parameters, which provide accurate inter­nuclear X—H (X = N, O) bond lengths and consequently a more accurate and precise depiction of the hydrogen-bond framework. PMID:27746937

  14. p-Cresyl sulfate and indoxyl sulfate in pediatric patients on chronic dialysis

    Directory of Open Access Journals (Sweden)

    Hye Sun Hyun

    2013-04-01

    Full Text Available &lt;b&gt;Purpose:&lt;/b&gt; Indoxyl sulfate and p- cresyl sulfate are important protein-bound uremic retention solutes whose levels can be partially reduced by renal replacement therapy. These solutes originate from intestinal bacterial protein fermentation and are associated with cardiovascular outcomes and chronic kidney disease progression. The aims of this study were to investigate the levels of indoxyl sulfate and p- cresyl sulfate as well as the effect of probiotics on reducing the levels of uremic toxins in pediatric patients on dialysis. &lt;b&gt;Methods:&lt;/b&gt; We enrolled 20 pediatric patients undergoing chronic dialysis; 16 patients completed the study. The patients underwent a 12-week regimen of VSL#3, a high-concentration probiotic preparation, and the serum levels of indoxyl sulfate and p- cresyl sulfate were measured before treatment and at 4, 8, and 12 weeks after the regimen by using fluorescence liquid chromatography. To assess the normal range of indoxyl sulfate and p- cresyl sulfate we enrolled the 16 children with normal glomerular filtration rate who had visited an outpatient clinic for asymptomatic microscopic hematuria that had been detected by a school screening in August 2011. &lt;b&gt;Results:&lt;/b&gt; The baseline serum levels of indoxyl sulfate and p- cresyl sulfate in the patients on chronic dialysis were significantly higher than those in the children with microscopic hematuria. The baseline serum levels of p- cresyl sulfate in the peritoneal dialysis group were significantly higher than those in the hemodialysis group. There were no significant changes in the levels of these uremic solutes after 12-week VSL#3 treatment in the patients on chronic dialysis. &lt;b&gt;Conclusion:&lt;/b&gt; The levels of the uremic toxins p- cresyl sulfate and indoxyl sulfate are highly elevated in pediatric patients on dialysis, but there was no significant effect by

  15. Sulfate-reducing bacteria: Microbiology and physiology

    Science.gov (United States)

    Peck, H. D.

    1985-01-01

    The sulfate reducing bacteria, the first nonphotosynthetic anaerobic bacteria demonstrated to contain c type cytochromes, perform electron transfer coupled to phosphorylation. A new bioenergetic scheme for the formation of a proton gradient for growth of Desulfovibrio on organic substrates and sulfate involving vectors electron transfer and consistent with the cellular localization of enzymes and electron transfer components was proposed. Hydrogen is produced in the cytoplasm from organic substrates and, as a permease molecule diffuses rapidly across the cytoplasmic membrane, it is oxidized to protons and electrons by the periplasmic hydrogenase. The electrons only are transferred across the cytoplasmic membrane to the cytoplasm where they are used to reduce sulfate to sulfide. The protons are used for transport or to drive a reversible ATPOSE. The net effect is the transfer of protons across the cytoplasmic membrane with the intervention of a proton pump. This type of H2 cycling is relevant to the bioenergetics of other types of anaerobic microorganisms.

  16. Sulfated glycopeptide nanostructures for multipotent protein activation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungsoo S.; Fyrner, Timmy; Chen, Feng; Álvarez, Zaida; Sleep, Eduard; Chun, Danielle S.; Weiner, Joseph A.; Cook, Ralph W.; Freshman, Ryan D.; Schallmo, Michael S.; Katchko, Karina M.; Schneider, Andrew D.; Smith, Justin T.; Yun, Chawon; Singh, Gurmit; Hashmi, Sohaib Z.; McClendon, Mark T.; Yu, Zhilin; Stock, Stuart R.; Hsu, Wellington K.; Hsu, Erin L.; Stupp , Samuel I. (NWU)

    2017-06-19

    Biological systems have evolved to utilize numerous proteins with capacity to bind polysaccharides for the purpose of optimizing their function. A well-known subset of these proteins with binding domains for the highly diverse sulfated polysaccharides are important growth factors involved in biological development and tissue repair. We report here on supramolecular sulfated glycopeptide nanostructures, which display a trisulfated monosaccharide on their surfaces and bind five critical proteins with different polysaccharide-binding domains. Binding does not disrupt the filamentous shape of the nanostructures or their internal β-sheet backbone, but must involve accessible adaptive configurations to interact with such different proteins. The glycopeptide nanostructures amplified signalling of bone morphogenetic protein 2 significantly more than the natural sulfated polysaccharide heparin, and promoted regeneration of bone in the spine with a protein dose that is 100-fold lower than that required in the animal model. These highly bioactive nanostructures may enable many therapies in the future involving proteins.

  17. Molecular Recognition and Ligand Association

    Science.gov (United States)

    Baron, Riccardo; McCammon, J. Andrew

    2013-04-01

    We review recent developments in our understanding of molecular recognition and ligand association, focusing on two major viewpoints: (a) studies that highlight new physical insight into the molecular recognition process and the driving forces determining thermodynamic signatures of binding and (b) recent methodological advances in applications to protein-ligand binding. In particular, we highlight the challenges posed by compensating enthalpic and entropic terms, competing solute and solvent contributions, and the relevance of complex configurational ensembles comprising multiple protein, ligand, and solvent intermediate states. As more complete physics is taken into account, computational approaches increase their ability to complement experimental measurements, by providing a microscopic, dynamic view of ensemble-averaged experimental observables. Physics-based approaches are increasingly expanding their power in pharmacology applications.

  18. Why mercury prefers soft ligands

    Energy Technology Data Exchange (ETDEWEB)

    Riccardi, Demian M [ORNL; Guo, Hao-Bo [ORNL; Gu, Baohua [ORNL; Parks, Jerry M [ORNL; Summers, Anne [University of Georgia, Athens, GA; Miller, S [University of California, San Francisco; Liang, Liyuan [ORNL; Smith, Jeremy C [ORNL

    2013-01-01

    Mercury (Hg) is a major global pollutant arising from both natural and anthropogenic sources. Defining the factors that determine the relative affinities of different ligands for the mercuric ion, Hg2+, is critical to understanding its speciation, transformation, and bioaccumulation in the environment. Here, we use quantum chemistry to dissect the relative binding free energies for a series of inorganic anion complexes of Hg2+. Comparison of Hg2+ ligand interactions in the gaseous and aqueous phases shows that differences in interactions with a few, local water molecules led to a clear periodic trend within the chalcogenide and halide groups and resulted in the well-known experimentally observed preference of Hg2+ for soft ligands such as thiols. Our approach establishes a basis for understanding Hg speciation in the biosphere.

  19. Crystal structure of a mixed-ligand dinuclear Ba-Zn complex with 2-meth-oxy-ethanol having tri-phenyl-acetate and chloride bridges.

    Science.gov (United States)

    Utko, Józef; Sobocińska, Maria; Dobrzyńska, Danuta; Lis, Tadeusz

    2015-07-01

    The dinuclear barium-zinc complex, μ-chlorido-1:2κ(2) Cl:Cl-chlorido-2κCl-bis-(2-meth-oxy-ethanol-1κO)bis-(2-meth-oxy-ethanol-1κ(2) O,O')bis-(μ-tri-phenyl-acetato-1:2κ(2) O:O')bariumzinc, [BaZn(C20H15O2)2Cl2(C3H8O2)4], has been synthesized by the reaction of barium tri-phenyl-acetate, anhydrous zinc chloride and 2-meth-oxy-ethanol in the presence of toluene. The barium and zinc metal cations in the dinuclear complex are linked via one chloride anion and carboxyl-ate O atoms of the tri-phenyl-acetate ligands, giving a Ba⋯Zn separation of 3.9335 (11) Å. The irregular nine-coordinate BaO8Cl coordination centres comprise eight O-atom donors, six of them from 2-meth-oxy-ethanol ligands (four from two bidentate O,O'-chelate inter-actions and two from monodentate inter-actions), two from bridging tri-phenyl-acetate ligands and one from a bridging Cl donor. The distorted tetra-hedral coordination sphere of zinc comprises two O-atom donors from the tri-phenyl-acetate ligands and two Cl donors (one bridging and one terminal). In the crystal, O-H⋯Cl, O-H⋯O and C-H⋯Cl inter-molecular inter-actions form a layered structure, lying parallel to (001).

  20. Formation of the natural sulfate aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Kerminen, V.M.; Hillamo, R.; Maekinen, M.; Virkkula, A.; Maekelae, T.; Pakkanen, T. [Helsinki Univ. (Finland). Dept. of Physics

    1996-12-31

    Anthropogenic sulfate aerosol, together with particles from biomass burning, may significantly reduce the climatic warming due to man-made greenhouse gases. The radiative forcing of aerosol particles is based on their ability to scatter and absorb solar radiation (direct effect), and on their influences on cloud albedos and lifetimes (indirect effect). The direct aerosol effect depends strongly on the size, number and chemical composition of particles, being greatest for particles of 0.1-1 {mu}m in diameter. The indirect aerosol effect is dictated by the number of particles being able to act as cloud condensation nuclei (CCN). For sulfate particles, the minimum CCN size in tropospheric clouds is of the order of 0.05-0.2 {mu}m. To improve aerosol parameterizations in future climate models, it is required that (1) both primary and secondary sources of various particle types will be characterized at a greater accuracy, and (2) the influences of various atmospheric processes on the spatial and temporal distribution of these particles and their physico-chemical properties are known much better than at the present. In estimating the climatic forcing due to the sulfate particles, one of the major problems is to distinguish between sulfur from anthropogenic sources and that of natural origin. Global emissions of biogenic and anthropogenic sulfate pre-cursors are comparable in magnitude, but over regional scales either of these two source types may dominate. The current presentation is devoted to discussing the natural sulfate aerosol, including the formation of sulfur-derived particles in the marine environment, and the use of particulate methanesulfonic acid (MSA) as a tracer for the natural sulfate

  1. Molybdate transport through the plant sulfate transporter SHST1.

    Science.gov (United States)

    Fitzpatrick, Kate L; Tyerman, Stephen D; Kaiser, Brent N

    2008-04-30

    Molybdenum is an essential micronutrient required by plants. The mechanism of molybdenum uptake in plants is poorly understood, however, evidence has suggested that sulfate transporters may be involved. The sulfate transporter from Stylosanthes hamata, SHST1, restored growth of the sulfate transport yeast mutant, YSD1, on media containing low amounts of molybdate. Kinetic analysis using 99MoO4(2-) demonstrated that SHST1 enhanced the uptake of molybdate into yeast cells at nM concentrations. Uptake was not inhibited by sulfate, but sulfate transport via SHST1 was reduced with molybdate. These results are the first measurement of molybdate transport by a characterised plant sulfate transport protein.

  2. On the evaporation of ammonium sulfate solution

    Energy Technology Data Exchange (ETDEWEB)

    Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

    2009-07-16

    Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 {+-} 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor-liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.

  3. New Mn(II, Ni(II, Cd(II, Pb(II complexes with 2-methylbenzimidazole and other ligands. Synthesis, spectroscopic characterization, crystal structure, magnetic susceptibility and biological activity studies

    Directory of Open Access Journals (Sweden)

    Shayma A. Shaker

    2016-11-01

    Full Text Available Synthesis and characterization of Mn(II, Ni(II, Cd(II and Pb(II mixed ligand complexes of 2-methylbenzimidazole with other ligands have been reported. The structure of the ligands and their complexes was investigated using elemental analysis, IR, UV–Vis, (1H, 13C NMR spectroscopy, molar conductivity and magnetic susceptibility measurements. In all the studies of complexes, the 2-methylbenzimidazole behaves as a neutral monodentate ligand which is coordinated with the metal ions through the N atom. While benzotriazole behaves as a neutral bidentate ligand which is coordinated with the Ni(II ion through the two N atoms. Moreover, the N-acetylglycine behaves as a bidentate ligand which is coordinated with the Mn(II, Ni(II and Pb(II ions through the N atom and the terminal carboxyl oxygen atom. The magnetic and spectral data indicate the tetrahedral geometry for Mn(II complex, irregular tetrahedral geometry for Pb(II complex and octahedral geometry for Ni(II complex. The X-ray single crystal diffraction method was used to confirm a centrosymmetric dinuclear Cd(II complex as each two metal ions are linked by a pair of thiocyanate N = S bridge. Two 2-methylbenzimidazole N-atom donors and one terminal thiocyanate N atom complete a highly distorted square pyramid geometry around the Cd atom. Besides, different cell types were used to determine the inhibitory effect of Mn(II, Ni(II, Cd(II and Pb(II complexes on cell growth using MTT assay. Cd(II complex showed cytotoxic effect on various types of cancer cell lines with different EC50 values.

  4. Selective sulfation of carrageenans and the influence of sulfate regiochemistry on anticoagulant properties.

    Science.gov (United States)

    de Araújo, Cristiano A; Noseda, Miguel D; Cipriani, Thales R; Gonçalves, Alan G; Duarte, Maria Eugênia R; Ducatti, Diogo R B

    2013-01-16

    Sulfated polysaccharides are recognized for their broad range of biological activities, including anticoagulant properties. The positions occupied by the sulfate groups are often related to the level of the inherent biological activity. Herein the naturally sulfated galactans, kappa-, iota- and theta-carrageenan, were additionally sulfated by regioselective means. The anticoagulant activity of the resulting samples was then studied using the aPTT in vitro assay. The influence of sulfate regiochemistry on the anticoagulant activity was evaluated. From kappa-carrageenan three rare polysaccharides were synthesized, one of them involved a synthetic route with an amphiphilic polysaccharide intermediate containing pivaloyl groups. Iota- and theta-carrageenan were utilized in a selective C6 sulfation at β-D-Galp units to produce different structures comprising trisulfated diads. All the samples were characterized by NMR (1D and 2D). The resulting aPPT measurements suggested that sulfation at C2 of 3,6-anhydro-α-D-Galp and C6 of β-D-Galp increased the anticoagulant activity.

  5. Ligand effects on the structures and magnetic properties of tricyanomethanide-containing copper(II) complexes.

    Science.gov (United States)

    Yuste, Consuelo; Bentama, Abdeslem; Stiriba, Salah-Eddine; Armentano, Donatella; De Munno, Giovanni; Lloret, Francesc; Julve, Miguel

    2007-11-28

    nitrogen atoms from two 2,3-dpp groups [Cu(1) and Cu(2)] either two terminally bound tcm ligands [Cu(1)] or a water molecule and a monodentate tcm ligand [Cu(2)] in cis positions. Magnetic susceptibility measurements for 1-4 in the temperature range 1.9-295 K reveal the occurrence of strong [J ca.-1000 cm(-1) (1); H = -JS(A) x S(B)] and weak [J = -0.13 (2), -0.67 (3) and -0.18 cm(-1) (4); H = -J Sigma(I)S(i) x S(i+1)] antiferromagnetic interactions in agreement with the different nature of the exchange pathways involved, diazine and single mu-hydroxo (1) and the extended 2,5-dpp (2), 2,3-dpp (3) and single mu-1,5-tcm (4) bridges with copper-copper separations of 3.363(8) (1), 7.111(1) (2), 6.823(1) and 7.056(1) (3) and 7.446(1) A (4).

  6. Activation and transfer of sulfate in biological systems (1960); Activation biologique du sulfate et son transfert (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Chapeville, F. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    It examines in this review the successive stages of active sulfate formation and its role in biological synthesis of sulfuric esters. The possible role of active sulfate as intermediary in sulfate reduction is also discussed. (author) [French] On examine dans cette etude les stades successifs de la mise en evidence du sulfate actif, son role dans la formation des esters sulfuriques de natures diverses, ainsi que sa participation eventuelle comme intermediaire au cours de la reduction du sulfate. On decrit aussi un procede de preparation du systeme biologique, generateur du sulfate actif et une methode de synthese chimique. (auteur)

  7. A race for RAGE ligands.

    Science.gov (United States)

    Schleicher, Erwin D

    2010-08-01

    In experimental animals a causal involvement of the multiligand receptor for advanced glycation end products (RAGE) in the development of diabetic vascular complications has been demonstrated. However, the nature of RAGE ligands present in patients with diabetic nephropathy has not yet been defined; this leaves open the relevance of the RAGE system to the human disease.

  8. METABOLISM OF SULFATE-REDUCING PROKARYOTES

    NARCIS (Netherlands)

    HANSEN, TA

    1994-01-01

    Dissimilatory sulfate reduction is carried out by a heterogeneous group of bacteria and archaea that occur in environments with temperatures up to 105 degrees C. As a group together they have the capacity to metabolize a wide variety of compounds ranging from hydrogen via typical organic fermentatio

  9. Sulfate-reducing bacteria in anaerobic bioreactors

    NARCIS (Netherlands)

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the

  10. Plasmin Regulation through Allosteric, Sulfated, Small Molecules

    Directory of Open Access Journals (Sweden)

    Rami A. Al-Horani

    2015-01-01

    Full Text Available Plasmin, a key serine protease, plays a major role in clot lysis and extracellular matrix remodeling. Heparin, a natural polydisperse sulfated glycosaminoglycan, is known to allosterically modulate plasmin activity. No small allosteric inhibitor of plasmin has been discovered to date. We screened an in-house library of 55 sulfated, small glycosaminoglycan mimetics based on nine distinct scaffolds and varying number and positions of sulfate groups to discover several promising hits. Of these, a pentasulfated flavonoid-quinazolinone dimer 32 was found to be the most potent sulfated small inhibitor of plasmin (IC50 = 45 μM, efficacy = 100%. Michaelis-Menten kinetic studies revealed an allosteric inhibition of plasmin by these inhibitors. Studies also indicated that the most potent inhibitors are selective for plasmin over thrombin and factor Xa, two serine proteases in coagulation cascade. Interestingly, different inhibitors exhibited different levels of efficacy (40%–100%, an observation alluding to the unique advantage offered by an allosteric process. Overall, our work presents the first small, synthetic allosteric plasmin inhibitors for further rational design.

  11. Sulfate reducing potential in an estuarine beach

    Digital Repository Service at National Institute of Oceanography (India)

    LokaBharathi, P.A.; Chandramohan, D.

    Sulfate reducing bacteria (SRB) and their activity (SRA) together with total anaerobic and aerobic bacterial flora were estimated during July 1982-April 1983 and July-August 1984 from 1, 3 and 5 cm depths using core samples. The average number (no...

  12. Sulfate-reducing bacteria in anaerobic bioreactors.

    NARCIS (Netherlands)

    Oude Elferink, S.J.W.H.

    1998-01-01

    The treatment of industrial wastewaters containing high amounts of easily degradable organic compounds in anaerobic bioreactors is a well-established process. Similarly, wastewaters which in addition to organic compounds also contain sulfate can be treated in this way. For a long time, the occurrenc

  13. Sulfate transport in Penicillium chrysogenum plasma membranes

    NARCIS (Netherlands)

    Hillenga, Dirk J.; Versantvoort, Hanneke J.M.; Driessen, Arnold J.M.; Konings, Wil N.

    1996-01-01

    Transport studies with Penicillium chrysogenum plasma membranes fused with cytochrome c oxidase liposomes demonstrate that sulfate uptake is driven by the transmembrane pH gradient and not by the transmembrane electrical potential. Ca2+ and other divalent cations are not required. It is concluded th

  14. Mechanisms and Effectivity of Sulfate Reducing Bioreactors ...

    Science.gov (United States)

    Mining-influenced water (MIW) is the main environmental challenges associated with the mining industry. Passive MIW remediation can be achieved through microbial activity in sulfate-reducing bioreactors (SRBRs), but their actual removal rates depend on different factors, one of which is the substrate composition. Chitinous materials have demonstrated high metal removal rates, particularly for the two recalcitrant MIW contaminants Zn and Mn, but their removal mechanisms need further study. We studied Cd, Fe, Zn, and Mn removal in bioactive and abiotic SRBRs to elucidate the metal removal mechanisms and the differences in metal and sulfate removal rates using a chitinous material as substrate. We found that sulfate-reducing bacteria are effective in increasing metal and sulfate removal rates and duration of operation in SRBRs, and that the main mechanism involved was metal precipitation as sulfides. The solid residues provided evidence of the presence of sulfides in the bioactive column, more specifically ZnS, according to XPS analysis. The feasibility of passive treatments with a chitinous substrate could be an important option for MIW remediation. Mining influenced water (MIW) remediation is still one of the top priorities for the agency because it addresses the most important environmental problem associated with the mining industry and that affects thousands of communities in the U.S. and worldwide. In this paper, the MIW bioremediation mechanisms are studied

  15. Lung injury in dimethyl sulfate poisoning

    Energy Technology Data Exchange (ETDEWEB)

    Ip, M.; Wong, K.L.; Wong, K.F.; So, S.Y.

    1989-02-01

    Two manual laborers were exposed to dimethyl sulfate during work and sustained mucosal injury to the eyes and respiratory tract. In one of them, noncardiogenic pulmonary edema occurred and improved with high-dose methylprednisolone. On follow-up for 10 months, this patient developed persistent productive cough with no evidence of bronchiectasis or bronchial hyperreactivity.

  16. Intravenous magnesium sulfate therapy in severe asthma

    Directory of Open Access Journals (Sweden)

    Mohd. Al-Ajmi

    2007-01-01

    Full Text Available A 22-year-old female, known asthmatic since seven years, developed severe bronchospasm in the preop-erative period. Bronchospasm remained unresponsive to the inhaled beta-agonist plus anticholinergic, IV ami-nophylline and hydrocortisone but responded quickly with magnesium sulfate® ( PSI, KSA infusion 1.25gm in 100ml normal saline over 20 minutes and another 1.25 gm over next 30 minutes as the initial infusion showed improvement in her clinical symptoms. Within half an hour of administering the 1st infusion of magnesium sulfate (1.25 gm the respiratory rate started reducing, rhonchi became less, SpO 2 came upto 92% and re-mained always above 90%. Encouraged by this result IV magnesium sulfate 2.5 gm in 500 ml normal saline was infused over next 24 hours along with alternate salbutamol and ipratropium nebulization every 6 hourly. With this treatment regimen the patient became asymptomatic within next 24 hours with normal clinical parameters and FEV 1 value. Hence it may be concluded that IV magnesium sulfate can be considered for patients with acute severe asthma who do not respond to standard therapeutic medications.

  17. Galactose 6-sulfate sulfatase activity in Morquio syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Yutaka, T.; Okada, S.; Kato, T.; Inui, K.; Yabuuhi, H. (Osaka Univ. (Japan). Faculty of Medicine)

    1982-07-01

    The authors have prepared a new substrate, o-..beta..-D-sulfo-galactosyl-(1-4)-..beta..-D-6-sulfo-2-acetamido-2-deoxyglucosyl-(1-4)-D-(1-/sup 3/H)galactitol, from shark cartilage keratan sulfate, for the assay of galactose 6-sulfate sulfatase activity. Using this substrate, they found there was a striking deficiency of galactose 6-sulfate sulfatase activity, in addition to the known deficiency of N-acetylgalactosamine 6-sulfate sulfatase, in the cultured skin fibroblasts of patients with Morquio syndrome. Their results could be explained by the hypothesis that accumulation of keratan sulfate and chondroitin 6-sulfate in Morquio syndrome is due to a deficiency of galactose 6-sulfate sulfatase and N-acetylgalactosamine 6-sulfate sulfatase activity, which are necessary for the degradation of these two mucopolysaccharides.

  18. Comparative Evaluation of Ankaferd Blood Stopper, Ferric Sulfate ...

    African Journals Online (AJOL)

    2016-07-24

    Jul 24, 2016 ... ferric sulfate (FS) as pulpotomy agent in primary teeth. Settings and Design: ... sulfate (FS), calcium hydroxide (CH), and mineral trioxide aggregate ..... internal root resorption may remain stable or may be repaired with hard ...

  19. Bacterial transport of sulfate, molybdate, and related oxyanions.

    Science.gov (United States)

    Aguilar-Barajas, Esther; Díaz-Pérez, César; Ramírez-Díaz, Martha I; Riveros-Rosas, Héctor; Cervantes, Carlos

    2011-08-01

    Sulfur is an essential element for microorganisms and it can be obtained from varied compounds, sulfate being the preferred source. The first step for sulfate assimilation, sulfate uptake, has been studied in several bacterial species. This article reviews the properties of different bacterial (and archaeal) transporters for sulfate, molybdate, and related oxyanions. Sulfate uptake is carried out by sulfate permeases that belong to the SulT (CysPTWA), SulP, CysP/(PiT), and CysZ families. The oxyanions molybdate, tungstate, selenate and chromate are structurally related to sulfate. Molybdate is transported mainly by the high-affinity ModABC system and tungstate by the TupABC and WtpABC systems. CysPTWA, ModABC, TupABC, and WtpABC are homologous ATP-binding cassette (ABC)-type transporters with similar organization and properties. Uptake of selenate and chromate oxyanions occurs mainly through sulfate permeases.

  20. Synthesis of Copper Nanoparticles Coated with Nitrogen Ligands

    Directory of Open Access Journals (Sweden)

    Rubén Sierra-Ávila

    2014-01-01

    Full Text Available The synthesis of copper nanoparticles was studied by wet chemical methods using copper sulfate pentahydrate (CuSO4·5H2O and nitrogen ligands allylamine (AAm and polyallylamine (PAAm as stabilizers. The results suggest that the use of these ligands leads to the exclusive formation of metallic copper nanoparticles (Cu-NPs. The use of partially crosslinked polyallylamine (PAAmc leads to nanoparticles (NPs with low yields and high coating content, while linear PAAm leads to NPs with high yields and low coating content. The chemical composition of the particles was determined by XRD and average particle diameters were determined by the Debye-Scherrer equation. TGA analysis provided evidence of the content and thermal stability of the coating on the nanoparticles and PAAm. The morphology, particle size distribution, and presence of PAAm coating were observed through TEM. The use of AAm in the synthesis of NPs could be a good alternative to reduce costs. By using TGA, TEM, and DSC techniques, it was determined that synthesized NPs with AAm presented a coating with similar characteristics to NPs with PAAm, suggesting that AAm underwent polymerization during the synthesis.

  1. The Importance of Sulfate Adenylyl Transferase in S and O Fractionation by Sulfate Reducing Bacteria

    Science.gov (United States)

    Smith, D. A.; Johnston, D. T.; Bradley, A. S.

    2016-12-01

    Microbial sulfate reduction (MSR) is critical to the oxidation of organic matter in modern and ancient oceans, and plays an important role in regulating the redox state of the Earth's surface. The sulfur and oxygen isotopic composition of seawater sulfate and of sulfate minerals reflect the biogeochemical processes that cycle sulfur, of which MSR is among the most important. MSR is a multi-enzymatic reaction network that partitions the isotopes of sulfur and oxygen as a consequence of both the flux of sulfate through this biochemical network and the fractionation imposed by each individual enzyme. MSR affects the δ18O of residual, extracellular sulfate mainly by the equilibration of the MSR intermediate sulfite with extracellular water (Antler et al., 2013 GCA, Wankel et al., 2013 Geobiol). A series of oxidative and exchange reactions catalyzed by APS reductase (APSr), sulfate adenylyl transferase (Sat), and sulfate transporters promote the conversion of water-equilibrated intracellular sulfite to extracellular sulfate. The flux of sulfoxy anions via these proteins will be, at least in part, dependent on the activity of these enzymes. To test this, we examined sulfur and oxygen isotope fractionation in genetically engineered mutants of the sulfate reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH). In these mutants, the activity of Sat has been artificially increased by perturbing the (i) transcriptional repressor Rex and (ii) its binding site upstream of the gene encoding Sat (Christensen et al., 2015 J. Bacteriol). It was predicted that this would minimize the back reaction of Sat, enhance the intracellular pool of APS, and minimize the equilibration between sulfite and adenosine monophosphate (AMP). Both mutants, along with the wild type DvH were grown in batch culture made with water enriched in 18O. Samples were collected throughout batch growth, and we report the evolution of the S and O isotopic composition of sulfate, and of the S isotopic

  2. Sources of sulfate supporting anaerobic metabolism in a contaminated aquifer

    Science.gov (United States)

    Ulrich, G.A.; Breit, G.N.; Cozzarelli, I.M.; Suflita, J.M.

    2003-01-01

    Field and laboratory techniques were used to identify the biogeochemical factors affecting sulfate reduction in a shallow, unconsolidated alluvial aquifer contaminated with landfill leachate. Depth profiles of 35S-sulfate reduction rates in aquifer sediments were positively correlated with the concentration of dissolved sulfate. Manipulation of the sulfate concentration in samples revealed a Michaelis-Menten-like relationship with an apparent Km and Vmax of approximately 80 and 0.83 ??M SO4-2??day-1, respectively. The concentration of sulfate in the core of the leachate plume was well below 20 ??M and coincided with very low reduction rates. Thus, the concentration and availability of this anion could limit in situ sulfate-reducing activity. Three sulfate sources were identified, including iron sulfide oxidation, barite dissolution, and advective flux of sulfate. The relative importance of these sources varied with depth in the alluvium. The relatively high concentration of dissolved sulfate at the water table is attributed to the microbial oxidation of iron sulfides in response to fluctuations of the water table. At intermediate depths, barite dissolves in undersaturated pore water containing relatively high concentrations of dissolved barium (???100 ??M) and low concentrations of sulfate. Dissolution is consistent with the surface texture of detrital barite grains in contact with leachate. Laboratory incubations of unamended and barite-amended aquifer slurries supported the field observation of increasing concentrations of barium in solution when sulfate reached low levels. At a deeper highly permeable interval just above the confining bottom layer of the aquifer, sulfate reduction rates were markedly higher than rates at intermediate depths. Sulfate is supplied to this deeper zone by advection of uncontaminated groundwater beneath the landfill. The measured rates of sulfate reduction in the aquifer also correlated with the abundance of accumulated iron sulfide

  3. 21 CFR 522.1484 - Neomycin sulfate sterile solution.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate sterile solution. 522.1484... § 522.1484 Neomycin sulfate sterile solution. (a) Specifications. Each milliliter of sterile aqueous solution contains 50 milligrams of neomycin sulfate (equivalent to 35 milligrams of neomycin base).1...

  4. 21 CFR 524.1484a - Neomycin sulfate ophthalmic ointment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Neomycin sulfate ophthalmic ointment. 524.1484a... § 524.1484a Neomycin sulfate ophthalmic ointment. (a) Specifications. Each gram of the ointment contains 5 milligrams of neomycin sulfate equivalent in activity to 3.5 milligrams of neomycin base....

  5. Nanocrystalline cellulose with various contents of sulfate groups.

    Science.gov (United States)

    Voronova, M I; Surov, O V; Zakharov, A G

    2013-10-15

    Properties of films derived from aqueous nanocrystalline cellulose dispersions by water evaporation depend on concentration of sulfate groups. Namely type of thermodestruction and surface morphology change as a function of contents of sulfate groups. Surface roughness increases and water adsorption enhances with increasing sulfate groups content particularly at high relative pressure.

  6. De Novo Sequencing of Complex Mixtures of Heparan Sulfate Oligosaccharides

    NARCIS (Netherlands)

    Huang, Rongrong; Zong, Chengli; Venot, Andre; Chiu, Yulun; Zhou, Dandan; Boons, Geert-Jan; Sharp, Joshua S

    2016-01-01

    Here, we describe the first sequencing method of a complex mixture of heparan sulfate tetrasaccharides by LC-MS/MS. Heparin and heparan sulfate (HS) are linear polysaccharides that are modified in a complex manner by N- and O-sulfation, N-acetylation, and epimerization of the uronic acid. Heparin an

  7. Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

    DEFF Research Database (Denmark)

    ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

    1994-01-01

    C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...

  8. Acid Sulfate Alteration in Gusev Crater, Mars

    Science.gov (United States)

    Morris, R. V.; Ming, D. W.; Catalano, J. G.

    2016-01-01

    The Mars Exploration Rover (MER) Spirit landed on the Gusev Crater plains west of the Columbia Hills in January, 2004, during the Martian summer (sol 0; sol = 1 Martian day = 24 hr 40 min). Spirit explored the Columbia Hills of Gusev Crater in the vicinity of Home Plate at the onset on its second winter (sol approximately 900) until the onset of its fourth winter (sol approximately 2170). At that time, Spirit became mired in a deposit of fined-grained and sulfate-rich soil with dust-covered solar panels and unfavorable pointing of the solar arrays toward the sun. Spirit has not communicated with the Earth since sol 2210 (January, 2011). Like its twin rover Opportunity, which landed on the opposite side of Mars at Meridiani Planum, Spirit has an Alpha Particle X-Ray Spectrometer (APXS) instrument for chemical analyses and a Moessbauer spectrometer (MB) for measurement of iron redox state, mineralogical speciation, and quantitative distribution among oxidation (Fe(3+)/sigma Fe) and coordination (octahedral versus tetrahedral) states and mineralogical speciation (e.g., olivine, pyroxene, ilmenite, carbonate, and sulfate). The concentration of SO3 in Gusev rocks and soils varies from approximately 1 to approximately 34 wt%. Because the APXS instrument does not detect low atomic number elements (e.g., H and C), major-element oxide concentrations are normalized to sum to 100 wt%, i.e., contributions of H2O, CO2, NO2, etc. to the bulk composition care not considered. The majority of Gusev samples have approximately 6 plus or minus 5 wt% SO3, but there is a group of samples with high SO3 concentrations (approximately 30 wt%) and high total iron concentrations (approximately 20 wt%). There is also a group with low total Fe and SO3 concentrations that is also characterized by high SiO2 concentrations (greater than 70 wt%). The trend labeled "Basaltic Soil" is interpreted as mixtures in variable proportions between unaltered igneous material and oxidized and SO3-rich basaltic

  9. Tyrosine sulfation of the amino terminus of PSGL-1 is critical for enterovirus 71 infection.

    Directory of Open Access Journals (Sweden)

    Yorihiro Nishimura

    Full Text Available Enterovirus 71 (EV71 is one of the major causative agents of hand, foot, and mouth disease, a common febrile disease in children; however, EV71 has been also associated with various neurological diseases including fatal cases in large EV71 outbreaks particularly in the Asia Pacific region. Recently we identified human P-selectin glycoprotein ligand-1 (PSGL-1 as a cellular receptor for entry and replication of EV71 in leukocytes. PSGL-1 is a sialomucin expressed on the surface of leukocytes, serves as a high affinity counterreceptor for selectins, and mediates leukocyte rolling on the endothelium. The PSGL-1-P-selectin interaction requires sulfation of at least one of three clustered tyrosines and an adjacent O-glycan expressing sialyl Lewis x in an N-terminal region of PSGL-1. To elucidate the molecular basis of the PSGL-1-EV71 interaction, we generated a series of PSGL-1 mutants and identified the post-translational modifications that are critical for binding of PSGL-1 to EV71. We expressed the PSGL-1 mutants in 293T cells and the transfected cells were assayed for their abilities to bind to EV71 by flow cytometry. We found that O-glycosylation on T57, which is critical for PSGL-1-selectin interaction, is not necessary for PSGL-1 binding to EV71. On the other hand, site-directed mutagenesis at one or more potential tyrosine sulfation sites in the N-terminal region of PSGL-1 significantly impaired PSGL-1 binding to EV71. Furthermore, an inhibitor of sulfation, sodium chlorate, blocked the PSGL-1-EV71 interaction and inhibited PSGL-1-mediated viral replication of EV71 in Jurkat T cells in a dose-dependent manner. Thus, the results presented in this study reveal that tyrosine sulfation, but not O-glycosylation, in the N-terminal region of PSGL-1 may facilitate virus entry and replication of EV71 in leukocytes.

  10. Tyrosine sulfation of the amino terminus of PSGL-1 is critical for enterovirus 71 infection.

    Directory of Open Access Journals (Sweden)

    Yorihiro Nishimura

    Full Text Available Enterovirus 71 (EV71 is one of the major causative agents of hand, foot, and mouth disease, a common febrile disease in children; however, EV71 has been also associated with various neurological diseases including fatal cases in large EV71 outbreaks particularly in the Asia Pacific region. Recently we identified human P-selectin glycoprotein ligand-1 (PSGL-1 as a cellular receptor for entry and replication of EV71 in leukocytes. PSGL-1 is a sialomucin expressed on the surface of leukocytes, serves as a high affinity counterreceptor for selectins, and mediates leukocyte rolling on the endothelium. The PSGL-1-P-selectin interaction requires sulfation of at least one of three clustered tyrosines and an adjacent O-glycan expressing sialyl Lewis x in an N-terminal region of PSGL-1. To elucidate the molecular basis of the PSGL-1-EV71 interaction, we generated a series of PSGL-1 mutants and identified the post-translational modifications that are critical for binding of PSGL-1 to EV71. We expressed the PSGL-1 mutants in 293T cells and the transfected cells were assayed for their abilities to bind to EV71 by flow cytometry. We found that O-glycosylation on T57, which is critical for PSGL-1-selectin interaction, is not necessary for PSGL-1 binding to EV71. On the other hand, site-directed mutagenesis at one or more potential tyrosine sulfation sites in the N-terminal region of PSGL-1 significantly impaired PSGL-1 binding to EV71. Furthermore, an inhibitor of sulfation, sodium chlorate, blocked the PSGL-1-EV71 interaction and inhibited PSGL-1-mediated viral replication of EV71 in Jurkat T cells in a dose-dependent manner. Thus, the results presented in this study reveal that tyrosine sulfation, but not O-glycosylation, in the N-terminal region of PSGL-1 may facilitate virus entry and replication of EV71 in leukocytes.

  11. Introduction of sulfate groups on poly(ethylene) surfaces by argon plasma immobilization of sodium alkyl sulfates

    NARCIS (Netherlands)

    Lens, J.P.; Terlingen, J.G.A.; Engbers, G.H.M.; Feijen, J.

    1998-01-01

    Sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by immobilizing a precoated layer of either sodium 10-undecene sulfate (S11(:)) or sodium dodecane sulfate (SDS) on the polymeric surface by means of an argon plasma treatment. For this purpose, S11(:

  12. ELECTRON DETACHMENT DISSOCIATION OF SYNTHETIC HEPARAN SULFATE GLYCOSAMINOGLYCAN TETRASACCHARIDES VARYING IN DEGREE OF SULFATION AND HEXURONIC ACID STEREOCHEMISTRY.

    Science.gov (United States)

    Leach, Franklin E; Arungundram, Sailaja; Al-Mafraji, Kanar; Venot, Andre; Boons, Geert-Jan; Amster, I Jonathan

    2012-12-15

    Glycosaminoglycan (GAG) carbohydrates provide a challenging analytical target for structural determination due to their polydisperse nature, non-template biosynthesis, and labile sulfate modifications. The resultant structures, although heterogeneous, contain domains which indicate a sulfation pattern or code that correlates to specific function. Mass spectrometry, in particular electron detachment dissociation Fourier transform ion cyclotron resonance (EDD FT-ICR MS), provides a highly sensitive platform for GAG structural analysis by providing cross-ring cleavages for sulfation location and product ions specific to hexuronic acid stereochemistry. To investigate the effect of sulfation pattern and variations in stereochemistry on EDD spectra, a series of synthetic heparan sulfate (HS) tetrasaccharides are examined. Whereas previous studies have focused on lowly sulfated compounds (0.5-1 sulfate groups per disaccharide), the current work extends the application of EDD to more highly sulfated tetrasaccharides (1-2 sulfate groups per disaccharide) and presents the first EDD of a tetrasaccharide containing a sulfated hexuronic acid. For these more highly sulfated HS oligomers, alternative strategies are shown to be effective for extracting full structural details. These strategies inlcude sodium cation replacement of protons, for determining the sites of sulfation, and desulfation of the oligosaccharides for the generation of product ions for assigning uronic acid stereochemistry.

  13. Prognostic significance of highly sulfated chondroitin sulfates in ovarian cancer defined by the single chain antibody GD3A11

    NARCIS (Netherlands)

    Steen, S.C.H.A. van der; Tilborg, A.G. van; Vallen, M.J.E.; Bulten, J.; Kuppevelt, T.H. van; Massuger, L.F.

    2016-01-01

    OBJECTIVE: The extracellular matrix (ECM) of ovarian cancer may provide a number of potential biomarkers. Chondroitin sulfate (CS), a class of sulfated polysaccharides, is abundantly present in the ECM of ovarian cancer. Structural alterations of CS chains (i.e. sulfation pattern) have been demonstr

  14. Manipulation of cellulose nanocrystal surface sulfate groups toward biomimetic nanostructures in aqueous media.

    Science.gov (United States)

    Zoppe, Justin O; Johansson, Leena-Sisko; Seppälä, Jukka

    2015-08-01

    We report a facile aqueous procedure to create multivalent displays of sulfonated ligands on CNCs for future applications as viral inhibitors. CNCs were decorated with model compounds containing sulfonate groups via reactions of epoxides and isothiocyanates with amines under alkaline conditions. At first, surface sulfate groups of CNCs were hydrolytically cleaved by alkaline hydrolysis to increase the number of available surface hydroxyls. Success of desulfation was confirmed via dynamic light scattering (DLS), zeta potential measurements and thermogravimetric analysis (TGA). CNC surface hydroxyl groups were then activated with epichlorohydrin before subsequent reactions. As proof of concept toward aqueous pathways for functionalizing nanoparticles with sulfonated ligands, 3-chloro-2-hydroxy-1-propanesulfonic acid sodium salt hydrate (CPSA) and 4-sulfophenyl isothiocyanate sodium salt monohydrate (4-SPITC) were chosen as model compounds to react with homobifunctional 2,2'-(ethylenedioxy)bis(ethylamine) (EBEA) molecular spacer. The approaches presented are not only applicable to polysaccharide nanocrystals, but also other classes of polymeric and inorganic substrates presenting surface hydroxyl groups, as in the case of poly(2-hydroxyethyl methacrylate) (PHEMA), silica or glass. CNCs carrying sulfonated ligands were characterized by ATR-FTIR and UV-vis spectroscopy. Surface chemical compositions of desired elements were determined via X-ray photoelectron spectroscopy (XPS). We anticipate that with these facile aqueous procedures as the proof of concept, a diverse library of target-specific functionalities can be conjugated to CNCs for applications in nanomedicine, especially related to viral inhibition.

  15. Controlled-deactivation cannabinergic ligands.

    Science.gov (United States)

    Sharma, Rishi; Nikas, Spyros P; Paronis, Carol A; Wood, Jodianne T; Halikhedkar, Aneetha; Guo, Jason Jianxin; Thakur, Ganesh A; Kulkarni, Shashank; Benchama, Othman; Raghav, Jimit Girish; Gifford, Roger S; Järbe, Torbjörn U C; Bergman, Jack; Makriyannis, Alexandros

    2013-12-27

    We report an approach for obtaining novel cannabinoid analogues with controllable deactivation and improved druggability. Our design involves the incorporation of a metabolically labile ester group at the 2'-position on a series of (-)-Δ(8)-THC analogues. We have sought to introduce benzylic substituents α to the ester group which affect the half-lives of deactivation through enzymatic activity while enhancing the affinities and efficacies of individual ligands for the CB1 and CB2 receptors. The 1'-(S)-methyl, 1'-gem-dimethyl, and 1'-cyclobutyl analogues exhibit remarkably high affinities for both CB receptors. The novel ligands are susceptible to enzymatic hydrolysis by plasma esterases in a controllable manner, while their metabolites are inactive at the CB receptors. In further in vitro and in vivo experiments key analogues were shown to be potent CB1 receptor agonists and to exhibit CB1-mediated hypothermic and analgesic effects.

  16. High rates of sulfate reduction in a low-sulfate hot spring microbial mat are driven by a low level of diversity of sulfate-respiring microorganisms

    DEFF Research Database (Denmark)

    Dillon, Jesse G; Fishbain, Susan; Miller, Scott R

    2007-01-01

    The importance of sulfate respiration in the microbial mat found in the low-sulfate thermal outflow of Mushroom Spring in Yellowstone National Park was evaluated using a combination of molecular, microelectrode, and radiotracer studies. Despite very low sulfate concentrations, this mat community...... was shown to sustain a highly active sulfur cycle. The highest rates of sulfate respiration were measured close to the surface of the mat late in the day when photosynthetic oxygen production ceased and were associated with a Thermodesulfovibrio-like population. Reduced activity at greater depths...... was correlated with novel populations of sulfate-reducing microorganisms, unrelated to characterized species, and most likely due to both sulfate and carbon limitation....

  17. Homodimerization Controls the Fibroblast Growth Factor 9 Subfamily's Receptor Binding and Heparan Sulfate-Dependent Diffusion in the Extracellular Matrix

    Energy Technology Data Exchange (ETDEWEB)

    Kalinina, J.; Byron, S; Makarenkova, H; Olsen, S; Eliseenkova, A; Larochelle, W; Dhanabal, M; Blais, S; Mohammadi, M; et. al.

    2009-01-01

    Uncontrolled fibroblast growth factor (FGF) signaling can lead to human diseases, necessitating multiple layers of self-regulatory control mechanisms to keep its activity in check. Herein, we demonstrate that FGF9 and FGF20 ligands undergo a reversible homodimerization, occluding their key receptor binding sites. To test the role of dimerization in ligand autoinhibition, we introduced structure-based mutations into the dimer interfaces of FGF9 and FGF20. The mutations weakened the ability of the ligands to dimerize, effectively increasing the concentrations of monomeric ligands capable of binding and activating their cognate FGF receptor in vitro and in living cells. Interestingly, the monomeric ligands exhibit reduced heparin binding, resulting in their increased radii of heparan sulfate-dependent diffusion and biologic action, as evidenced by the wider dilation area of ex vivo lung cultures in response to implanted mutant FGF9-loaded beads. Hence, our data demonstrate that homodimerization autoregulates FGF9 and FGF20's receptor binding and concentration gradients in the extracellular matrix. Our study is the first to implicate ligand dimerization as an autoregulatory mechanism for growth factor bioactivity and sets the stage for engineering modified FGF9 subfamily ligands, with desired activity for use in both basic and translational research.

  18. Privileged chiral ligands and catalysts

    CERN Document Server

    Zhou, Qi-Lin

    2011-01-01

    This ultimate ""must have"" and long awaited reference for every chemist working in the field of asymmetric catalysis starts with the core structure of the catalysts, explaining why a certain ligand or catalyst is so successful. It describes in detail the history, the basic structural characteristics, and the applications of these ""privileged catalysts"". A novel concept that gives readers a much deeper insight into the topic.

  19. Effect of magnetic field on the crystallization of zinc sulfate

    Directory of Open Access Journals (Sweden)

    Freitas A. M. B.

    2000-01-01

    Full Text Available The effect of magnetic field on the crystallization of diamagnetic zinc sulfate was investigated in a series of controlled batch cooling experiments. Zinc sulfate solutions were exposed to magnetic fields of different intensities, up to a maximum of 0.7T. A clear influence of magnetic field on the following zinc sulfate crystallization parameters was found: an increase in saturation temperature, a decrease in metastable zone width, and an increase in growth rate and average crystal size. These effects were observed for the diamagnetic zinc sulfate, but not in similar, previously reported experiments for paramagnetic copper sulfate.

  20. Tumor targeting via integrin ligands

    Directory of Open Access Journals (Sweden)

    Udaya Kiran eMarelli

    2013-08-01

    Full Text Available Selective and targeted delivery of drugs to tumors is a major challenge for an effective cancer therapy and also to overcome the side effects associated with current treatments. Overexpression of various receptors on tumor cells is a characteristic structural and biochemical aspect of tumors and distinguishes them from physiologically normal cells. This abnormal feature is therefore suitable for selectively directing anticancer molecules to tumors by using ligands that can preferentially recognize such receptors. Several subtypes of integrin receptors that are crucial for cell adhesion, cell signaling, cell viability and motility have been shown to have an upregulated expression on cancer cells. Thus, ligands that recognize specific integrin subtypes represent excellent candidates to be conjugated to drugs or drug carrier systems and be targeted to tumors. In this regard, integrins recognizing the RGD cell adhesive sequence have been extensively targeted for tumor specific drug delivery. Here we review key recent examples on the presentation of RGD-based integrin ligands by means of distinct drug delivery systems, and discuss the prospects of such therapies to specifically target tumor cells.

  1. Two Zn(II) coordination complexes assembled by trithiocyanuric acid and two different N-donor auxiliary ligands.

    Science.gov (United States)

    He, Xiao Xiao; Guo, Ya Mei

    2014-08-01

    The dipyridyl-type building blocks 4-amino-3,5-bis(pyridin-3-yl)-1,2,4-triazole (3-bpt) and 4,4'-bipyridine (bpy) have been used to assemble with Zn(II) in the presence of trithiocyanuric acid (ttcH3) to afford two coordination compounds, namely bis[4-amino-3,5-bis(pyridin-3-yl)-1,2,4-triazole-κN(3)]bis(trithiocyanurato-κ(2)N,S)zinc(II), [Zn(C3H2N3S3)2(C12H10N6)2]·2H2O, (1), and catena-poly[[[bis(trithiocyanurato-κ(2)N,S)zinc(II)]-μ-4,4'-bipyridine-κ(2)N:N'] 4,4'-bipyridine monosolvate], {[Zn2(C3H2N3S3)4(C10H8N2)3]·C10H8N2}n, (2). Single-crystal X-ray analysis indicates that complex (1) is a mononuclear structure, while complex (2) presents a one-dimensional chain coordination motif. In both complexes, the central Zn(II) cation adopts an octahedral geometry, coordinated by four N- and two S-donor atoms. Notably, trithiocyanurate (ttcH2(-)) adopts the same bidentate chelating coordination mode in each complex and exists in the thione tautomeric form. The 3-bpt co-ligand in (1) adopts a monodentate coordination mode and serves as a terminal pendant ligand, whereas the 4,4'-bipyridine (bpy) ligand in (2) adopts a bidentate-bridging coordination mode. The different coordination characters of the different N-donor auxiliary ligands lead to structural diversity for complexes (1) and (2). Further analysis indicates that the resultant three-dimensional supramolecular networks for (1) and (2) arise through intermolecular N-H...S and N-H...N hydrogen bonds. Both complexes have been further characterized by FT-IR spectroscopy and elemental analyses.

  2. 3'-Phosphoadenosine-5'-phosphosulfate: Photoaffinity ligand for sulfotransferase enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Otterness, D.M.; Powers, S.P.; Miller, L.J.; Weinshilboum, R.M. (Mayo Clinic/Mayo Foundation, Rochester, MN (USA))

    1991-01-01

    Sulfation is an important pathway in the biotransformation of many drugs, xenobiotic compounds, neurotransmitters, and hormones. The sulfate donor for these reactions is 3'-phosphoadenosine-5'-phosphosulfate (PAPS). We set out to determine whether PAPS might serve as a photoaffinity ligand for sulfotransferase enzymes. UV irradiation of (35S)PAPS with partially purified human liver thermostable (TS) phenol sulfotransferase (PST) radioactively labeled a protein with a molecular mass of 35 kDa, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Photoaffinity labeling of TS PST with (35S) PAPS did not require the presence of a phenolic substrate but rather was inhibited by p-nitrophenol, a sulfate acceptor substrate for TS PST. Inhibitors of TS PST enzymatic activity, including 3'-phosphoadenosine-5'-phosphate, ATP, ADP, and 2,6-dichloro-4-nitrophenol, also inhibited photoaffinity labeling of the 35-kDa protein with (35S)PAPS, in a concentration-dependent fashion, with IC50 values of 14 microM, 2.1 mM, 7.7 mM, and 91 microM, respectively. The 35-kDa protein that was radioactively labeled by (35S)PAPS in the presence of UV light coeluted with TS PST enzymatic activity during gel filtration high performance liquid chromatography. (35S)PAPS was then used to photoaffinity label another sulfotransferase enzyme, the thermolabile (TL) form of PST partially purified from human liver. Therefore, (35S)PAPS appears to be a photoaffinity ligand that could be used to study a variety of PAPS-dependent sulfotransferases. Photoaffinity labeling of TS and TL PST, as well as other PAPS-dependent sulfotransferases, should enhance our ability to purify this important group of enzymes and to determine amino acid sequences at or near their active sites.

  3. Sulfate and acid resistant concrete and mortar

    Science.gov (United States)

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

    1998-01-01

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance while maintaining acceptable compressive strength properties. The acid and sulfate hardenable mixtures of the invention containing fly ash comprise cementitious materials and a fine aggregate. The cementitous materials may comprise fly ash as well as cement. The fine aggregate may comprise fly ash as well as sand. The total amount of fly ash in the hardenable mixture ranges from about 60% to about 120% of the total amount of cement, by weight, whether the fly ash is included as a cementious material, fine aggregate, or an additive, or any combination of the foregoing. In specific examples, mortar containing 50% fly ash and 50% cement in cementitious materials demonstrated superior properties of corrosion resistance.

  4. Effects of sulfate chitosan derivatives on nonalcoholic fatty liver disease

    Science.gov (United States)

    Yu, Mingming; Wang, Yuanhong; Jiang, Tingfu; Lv, Zhihua

    2014-06-01

    Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentration emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly ameliorated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD.

  5. Effects of Sulfate Chitosan Derivatives on Nonalcoholic Fatty Liver Disease

    Institute of Scientific and Technical Information of China (English)

    YU Mingming; WANG Yuanhong; JIANG Tingfu; LV Zhihua

    2014-01-01

    Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentra-tion emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly amelio-rated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD.

  6. The Importance of Heparan Sulfate in Herpesvirus Infection

    Institute of Scientific and Technical Information of China (English)

    Christopher D.O'Donnell; Deepak Shukla

    2008-01-01

    Herpes simplex virus type-1 (HSV-1) is one of many pathogens that use the cell surface glycosaminoglycan heparan sulfate as a receptor.Heparan sulfate is highly expressed on the surface and extracellular matrix of virtually all cell types making it an ideal receptor.Heparan sulfate interacts with HSV-1 envelope glycoproteins gB and gC during the initial attachment step during HSV-1 entry.In addition,a modified form of heparan sulfate,known as 3-O-sulfated heparan sulfate,interacts with HSV-1 gD to induce fusion between the viral envelope and host cell membrane.The 3-O-sulfation of heparan sulfate is a rare modification which occurs during the biosynthesis of heparan sulfate that is carded out by a family of enzymes known as 3-O-sulfotransferases.Due to its involvement in multiple steps of the infection process,heparan sulfate has been a prime target for the development of agents to inhibit HSV entry.Understanding how heparan sulfate functions during HSV-1 infection may not only be critical for inhibiting infection by this virus,but it may also be crucial in the fight against many other pathogens as well.

  7. Cholesterol sulfate in human physiology: what's it all about?

    Science.gov (United States)

    Strott, Charles A; Higashi, Yuko

    2003-07-01

    Cholesterol sulfate is quantitatively the most important known sterol sulfate in human plasma, where it is present in a concentration that overlaps that of the other abundant circulating steroid sulfate, dehydroepiandrosterone (DHEA) sulfate. Although these sulfolipids have similar production and metabolic clearance rates, they arise from distinct sources and are metabolized by different pathways. While the function of DHEA sulfate remains an enigma, cholesterol sulfate has emerged as an important regulatory molecule. Cholesterol sulfate is a component of cell membranes where it has a stabilizing role, e.g., protecting erythrocytes from osmotic lysis and regulating sperm capacitation. It is present in platelet membranes where it supports platelet adhesion. Cholesterol sulfate can regulate the activity of serine proteases, e.g., those involved in blood clotting, fibrinolysis, and epidermal cell adhesion. As a result of its ability to regulate the activity of selective protein kinase C isoforms and modulate the specificity of phosphatidylinositol 3-kinase, cholesterol sulfate is involved in signal transduction. Cholesterol sulfate functions in keratinocyte differentiation, inducing genes that encode for key components involved in development of the barrier. The accumulating evidence demonstrating a regulatory function for cholesterol sulfate appears solid; the challenge now is to work out the molecular mechanisms whereby this interesting molecule carries out its various roles.

  8. Sulfate was a trace constituent of Archean seawater

    DEFF Research Database (Denmark)

    Crowe, Sean Andrew; Paris, Guillaume; Katsev, Sergei

    2014-01-01

    In the low-oxygen Archean world (>2400 million years ago), seawater sulfate concentrations were much lower than today, yet open questions frustrate the translation of modern measurements of sulfur isotope fractionations into estimates of Archean seawater sulfate concentrations. In the water column...... of Lake Matano, Indonesia, a low-sulfate analog for the Archean ocean, we find large (>20 per mil) sulfur isotope fractionations between sulfate and sulfide, but the underlying sediment sulfides preserve a muted range of delta S-34 values. Using models informed by sulfur cycling in Lake Matano, we infer...... Archean seawater sulfate concentrations of less than 2.5 micromolar. At these low concentrations, marine sulfate residence times were likely 10(3) to 10(4) years, and sulfate scarcity would have shaped early global biogeochemical cycles, possibly restricting biological productivity in Archean oceans....

  9. Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

    DEFF Research Database (Denmark)

    ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

    1994-01-01

    Sulfate reduction was measured with the (SO42-)-S-35-tracer technique in slurries of sediment from Aarhus Bay, Denmark, where seasonal temperatures range from 0 degrees to 15 degrees C. The incubations were made at temperatures from 0 degrees C to 80 degrees C in temperature increments of 2 degrees...... C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...

  10. Studies on the binding of amylopectin sulfate with gastric mucin.

    Science.gov (United States)

    Kim, Y S; Bella, A; Whitehead, J S; Isaacs, R; Remer, L

    1975-07-01

    Amylopectin sulfate, a sulfated polysaccharide that has an antipeptic property, was examined for its ability to bind gastric mucins. After chemically cross-linking the amylopectin sulfate into an insoluble gel, its binding with mucins isolated from antral and fundic mucosa of canine stomachs was studied with chromatography. A component present in both mucin fractions bound to the amylopectin sulfate gel below pH 4.5. This binding was reversible, and the complex dissociated above pH 5. Similar binding properties were found with soluble amylopectin sulfate. The component of the mucine which bound to amylopectin sulfate differed from the one which did not bind in its electrophoretic mobility and in its higher proportion of basic amino acids and a lower hexosamine, serine, and threonine content. This study suggests that amylopectin sulfate may bind to gastric mucins only under conditions of low pH.

  11. Contrasting coordination behavior of Group 12 perchlorate salts with an acyclic N3O2 donor ligand by X-ray crystallography and (1)H NMR.

    Science.gov (United States)

    Tice, Daniel B; Pike, Robert D; Bebout, Deborah C

    2016-08-09

    An unbranched N3O2 ligand 2,6-bis[((2-pyridinylmethyl)oxy)methyl]pyridine (L1) was used to prepare new mononuclear heteroleptic Group 12 perchlorate complexes characterized by IR, (1)H NMR and X-ray crystallography. Racemic complexes with pentadentate L1 and one to four oxygens from either water or perchlorate bound to a metal ion were structurally characterized. Octahedral [Zn(L1)(OH2)](ClO4)2 (1) and pentagonal bipyramidal [Cd(L1)(OH2)(OClO3)]ClO4 (2) structures were found with lighter congeners. The polymorphic forms of [Hg(L1)(ClO4)2] characterized (3 in P1[combining macron] and 4 in P21/c) had a mix of monodentate, anisobidentate and bidentate perchlorates, providing the first examples of a tricapped trigonal prismatic Hg(ii) coordination geometry, as well as additional examples of a rare square antiprismatic Hg(ii) coordination geometry. Solution state (1)H NMR characterization of the Group 12 complexes in CD3CN indicated intramolecular reorganization remained rapid under conditions where intermolecular M-L1 exchange was slow on the chemical shift time scale for Zn(ii) and on the J(M(1)H) time scale for Cd(ii) and Hg(ii). Solution studies with more than one equivalent of ligand also suggested that a complex with a 1 : 2 ratio of M : L1 contributed significantly to solution equilibria with Hg(ii) but not the other metal ions. The behavior of related linear pentadentate ligands with Group 12 perchlorate salts is discussed.

  12. Nickel hydroxide precipitation from aqueous sulfate media

    Science.gov (United States)

    Sist, Cinziana; Demopoulos, George P.

    2003-08-01

    Hydrometallurgical processing of laterite ores constitutes a major industrial and R&D activity in extractive metallurgy. In some of the process flowsheets, nickel hydroxide precipitation is incorporated. For these operations, the optimization of nickel hydroxide precipitation is important to assure efficiency and product quality. The main objective of this investigation was to study and improve the precipitation characteristics of Ni(OH)2 in a sulfate system using supersaturation controlled precipitation.

  13. Engineering sulfotransferases to modify heparan sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ding; Moon, Andrea F.; Song, Danyin; Pedersen, Lars C.; Liu, Jian (NIH); (UNC)

    2008-03-19

    The biosynthesis of heparan sulfate (HS) involves an array of specialized sulfotransferases. Here, we present a study aimed at engineering the substrate specificity of different HS 3-O-sulfotransferase isoforms. Based on the crystal structures, we identified a pair of amino acid residues responsible for selecting the substrates. Mutations of these residues altered the substrate specificities. Our results demonstrate the feasibility of tailoring the specificity of sulfotransferases to modify HS with desired functions.

  14. XAFS studies of metal-ligand interactions at organic surfaces and in solution

    Science.gov (United States)

    Boyanov, Maxim I.

    X-ray absorption fine structure spectroscopy (XAFS) was used as a structural probe to determine the mechanism of metal adsorption to organic surfaces. Two specific systems were investigated, Pb adsorption to heneicosanoic acid Langmuir monolayers (CH3(CH2)19COOH), and Cd adsorption to isolated cell walls of the Bacillus subtilis bacterium. Although the study of these systems is important for quite different reasons, the goal in both is metal binding site speciation and structural characterization of the surface complex. The adsorption of aqueous Cd to B. subtilis was studied as a function of pH by fluorescence mode bulk XAFS. Samples were prepared at six pH values in the range 3.4 to 7.8, and the bacterial functional groups responsible for the adsorption were identified under each condition. Under the experimental Cd and bacterial concentrations, the spectroscopy results indicate that Cd binds predominantly to protonated phosphoryl ligands below pH 4.4, while at higher pH adsorption to carboxyl groups becomes increasingly important. At pH 7.8 we observe the activation of an additional binding site, which we tentatively ascribe to deprotonated phosphoryl ligands. A quantitative Cd speciation diagram for the pH range is presented. Grazing-incidence Pb L3 edge XAFS was used in situ to determine the adsorption complex structure in the Pb-Langmuir monolayer study. The results indicate covalent binding of the Pb cations to the carboxyl headgroups, and the observed Pb-Pb coordination suggests that the metal is adsorbed as a hydrolysis polymer, rather than as individual Pb 2+ ions. The data suggest a bidentate binding mechanism and a one Pb atom to one carboxyl headgroup binding stoichiometry. We discuss how this adsorption model can explain the peculiarities observed with Pb in previous metal-Langmuir monolayer studies. A systematic study of the metal local environment in aqueous solutions was conducted and used in the above analyses. Perchlorate and acetate salt

  15. Pseudohalide copper(II) complexes derived from polypyridyl ligands: Synthesis and characterization

    Science.gov (United States)

    Mautner, Franz A.; Louka, Febee R.; LeGuet, Thibaut; Massoud, Salah S.

    2009-02-01

    A novel series of pseudohalide- ( N3- NCS -) and perchlorato-Cu(II) complexes possessing a series of ligands with pyridyl-containing donors have been investigated. These include [Cu(pmap)ClO 4)]ClO 4 ( 1), [Cu(pmap)(N 3)]ClO 4 ( 2), [Cu(pmea)(N 3)]ClO 4·H 2O ( 3), [Cu(dp-pa)(N 3)]ClO 4·½H 2O ( 4), [Cu(pzdepy)ClO 4]ClO 4 ( 5), [Cu(pzdepy)(NCS)]ClO 4 ( 6) and [Cu 2(L)(NCS) 4]·2CH 3CN ( 7) where pmap = bis[2-(2-pyridylethyl)]-(2-pyridylmethyl)amine, pmea = bis(2-pyridylmethyl)-2-(2-pyridylethyl)amine, dp-pa = N-propanamide- N, N-bis(2-pyridylmethyl)amine, pzdepy = N, N'-bis[2-(2-pyridylethyl)]piperazine and L = 3,5-bis[bis(2-pyridylmethyl)aminomethyl]-toluene. All complexes were characterized by elemental analyses, IR and UV-Visible spectroscopy. The visible spectra of all complexes reveal the square-pyramidal geometries (SP) around the central Cu 2+ ion. IR spectra confirmed the coordination of the ClO4- group in 1 and 5 and the N-donor thiocyanate group in complexes 6 and 7. The X-ray structure determination of the pseudohalide complexes 2, 6 and 7 confirmed the monodentate coordination nature of N3- and NCS - ions. The structure of 2 or 6 consists of isolated [Cu(pmap)(N 3)] + or [Cu(pzdepy)(NCS)] + cations and perchlorate counter anions. The copper centers are penta-coordinated by the four N atoms of the pmap or pzdepy and N(5) atom of the azide group in 2 and the thiocyanate group in 6. In the dinuclear unit [Cu 2(L)(NCS) 4] of 7, each copper atom forms bonds to three nitrogen atoms of the ligand L, [Cu sbnd N bonds from 2.013(2) to 2.054(2) Å], and to N(4) and N(5) atoms of the two terminal thiocyanato groups [Cu(1) sbnd N(4) = 1.954(2) Å; Cu(1) sbnd N(5) = 2.178(2) Å]. The intradimer Cu(1)...Cu(1A) distance is 5.7010(14) Å. An intramolecular π-π stacking with a ring-ring separation of 3.5991(14) Å is observed between the central benzene ring and the pyridyl rings. In the three complexes ( 2, 6 and 7), the CuN 5 chromophore may be described as an

  16. Galactose 6-O-sulfotransferases are not required for the generation of Siglec-F ligands in leukocytes or lung tissue.

    Science.gov (United States)

    Patnode, Michael L; Cheng, Chu-Wen; Chou, Chi-Chi; Singer, Mark S; Elin, Matilda S; Uchimura, Kenji; Crocker, Paul R; Khoo, Kay-Hooi; Rosen, Steven D

    2013-09-13

    Eosinophil accumulation is a characteristic feature of the immune response to parasitic worms and allergens. The cell surface carbohydrate-binding receptor Siglec-F is highly expressed on eosinophils and negatively regulates their accumulation during inflammation. Although endogenous ligands for Siglec-F have yet to be biochemically defined, binding studies using glycan arrays have implicated galactose 6-O-sulfate (Gal6S) as a partial recognition determinant for this receptor. Only two sulfotransferases are known to generate Gal6S, namely keratan sulfate galactose 6-O-sulfotransferase (KSGal6ST) and chondroitin 6-O-sulfotransferase 1 (C6ST-1). Here we use mice deficient in both KSGal6ST and C6ST-1 to determine whether these sulfotransferases are required for the generation of endogenous Siglec-F ligands. First, we characterize ligand expression on leukocyte populations and find that ligands are predominantly expressed on cell types also expressing Siglec-F, namely eosinophils, neutrophils, and alveolar macrophages. We also detect Siglec-F ligand activity in bronchoalveolar lavage fluid fractions containing polymeric secreted mucins, including MUC5B. Consistent with these observations, ligands in the lung increase dramatically during infection with the parasitic nematode, Nippostrongylus brasiliensis, which is known to induce eosinophil accumulation and mucus production. Surprisingly, Gal6S is undetectable in sialylated glycans from eosinophils and BAL fluid analyzed by mass spectrometry. Furthermore, none of the ligands we describe are diminished in mice lacking KSGal6ST and C6ST-1, indicating that neither of the known galactose 6-O-sulfotransferases is required for ligand synthesis. These results establish that ligands for Siglec-F are present on several cell types that are relevant during allergic lung inflammation and argue against the widely held view that Gal6S is critical for glycan recognition by this receptor.

  17. Sulfation and Cation Effects on the Conformational Properties of the Glycan Backbone of Chondroitin Sulfate Disaccharides

    Science.gov (United States)

    Faller, Christina E.; Guvench, Olgun

    2015-01-01

    Chondroitin sulfate (CS) is one of several glycosaminoglycans that are major components of proteoglycans. A linear polymer consisting of repeats of the disaccharide -4GlcAβ1-3GalNAcβ1-, CS undergoes differential sulfation resulting in five unique sulfation patterns. Because of the dimer repeat, the CS glycosidic “backbone” has two distinct sets of conformational degrees of freedom defined by pairs of dihedral angles: (ϕ1, ψ1) about the β1-3 glycosidic linkage and (ϕ2, ψ2) about the β1-4 glycosidic linkage. Differential sulfation and the possibility of cation binding, combined with the conformational flexibility and biological diversity of CS, complicate experimental efforts to understand CS three-dimensional structures at atomic resolution. Therefore, all-atom explicit-solvent molecular dynamics simulations with Adaptive Biasing Force sampling of the CS backbone were applied to obtain high resolution, high precision free energies of CS disaccharides as a function of all possible backbone geometries. All ten disaccharides (β1-3 vs. β1-4 linkage x five different sulfation patterns) were studied; additionally, ion effects were investigated by considering each disaccharide in the presence of either neutralizing sodium or calcium cations. GlcAβ1-3GalNAc disaccharides have a single, broad, thermodynamically important free-energy minimum whereas GalNAcβ1-4GlcA disaccharides have two such minima. Calcium cations but not sodium cations bind to the disaccharides, and binding is primarily to the GlcA –COO− moiety as opposed to sulfate groups. This binding alters the glycan backbone thermodynamics in instances where a calcium cation bound to –COO− can act to bridge and stabilize an interaction with an adjacent sulfate group, whereas, in the absence of this cation, the proximity of a sulfate group to –COO− results in two like charges being both desolvated and placed adjacent to each other and is found to be destabilizing. In addition to providing

  18. Conformation of sulfated galactan and sulfated fucan in aqueous solutions: implications to their anticoagulant activities.

    Science.gov (United States)

    Becker, Camila F; Guimarães, Jorge A; Mourão, Paulo A S; Verli, Hugo

    2007-07-01

    The discovery of sulfated galactans and sulfated fucans in marine invertebrates with simple and ordered structures opened new perspectives to investigate the biological activity of these molecules and to determine whether different structures confer high affinity for a particular protein. We undertook a conformational analysis of a 2-sulfated, 3-linked alpha-L-galactan and of a alpha-L-fucan with similar structure. Through comparison between theoretical and NMR derived coupling constants, we observed that the pyranose rings are predominantly in the (1)C(4) conformation in these polysaccharides. Additionally, the geometry of the glycosidic linkages was determined based on force field calculations, indicating that the two polysaccharides have similar conformations in solution. Since the sulfated alpha-L-galactan, but not the alpha-L-fucan potentiates antithrombin (AT) inhibition of thrombin, the solution conformations of the compounds were docked into AT and the complexes obtained were refined through molecular dynamics calculations. The obtained results indicates extremely different orientations for the two polysaccharides, which well correlates and explain their distinct anticoagulant activities. Finally, the molecular mechanism of a selective 2-desulfation reaction, observed among sulfated fucans, was explained as a consequence of an intramolecular hydrogen bond capable of assisting in the removal of the charged group.

  19. Cationic lipids and cationic ligands induce DNA helix denaturation: detection of single stranded regions by KMnO4 probing.

    Science.gov (United States)

    Prasad, T K; Gopal, Vijaya; Rao, N Madhusudhana

    2003-09-25

    Cationic lipids and cationic polymers are widely used in gene delivery. Using 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) as a cationic lipid, we have investigated the stability of the DNA in DOTAP:DNA complexes by probing with potassium permanganate (KMnO4). Interestingly, thymidines followed by a purine showed higher susceptibility to cationic ligand-mediated melting. Similar studies performed with other water-soluble cationic ligands such as polylysine, protamine sulfate and polyethyleneimine also demonstrated melting of the DNA but with variations. Small cations such as spermine and spermidine and a cationic detergent, cetyl trimethylammonium bromide, also rendered the DNA susceptible to modification by KMnO4. The data presented here provide direct proof for melting of DNA upon interaction with cationic lipids. Structural changes subsequent to binding of cationic lipids/ligands to DNA may lead to instability and formation of DNA bubbles in double-stranded DNA.

  20. Heritability and clinical determinants of serum indoxyl sulfate and p-cresyl sulfate, candidate biomarkers of the human microbiome enterotype.

    Directory of Open Access Journals (Sweden)

    Liesbeth Viaene

    Full Text Available BACKGROUND: Indoxyl sulfate and p-cresyl sulfate are unique microbial co-metabolites. Both co-metabolites have been involved in the pathogenesis of accelerated cardiovascular disease and renal disease progression. Available evidence suggests that indoxyl sulfate and p-cresyl sulfate may be considered candidate biomarkers of the human enterotype and may help to explain the link between diet and cardiovascular disease burden. OBJECTIVE AND DESIGN: Information on clinical determinants and heritability of indoxyl sulfate and p-cresyl sulfate serum is non-existing. To clarify this issue, the authors determined serum levels of indoxyl sulfate and p-cresyl sulfate in 773 individuals, recruited in the frame of the Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO study. RESULTS: Serum levels of indoxyl sulfate and p-cresyl sulfate amounted to 3.1 (2.4-4.3 and 13.0 (7.4-21.5 μM, respectively. Regression analysis identified renal function, age and sex as independent determinants of both co-metabolites. Both serum indoxyl sulfate (h2 = 0.17 and p-cresyl sulfate (h2 = 0.18 concentrations showed moderate but significant heritability after adjustment for covariables, with significant genetic and environmental correlations for both co-metabolites. LIMITATIONS: Family studies cannot provide conclusive evidence for a genetic contribution, as confounding by shared environmental effects can never be excluded. CONCLUSIONS: The heritability of indoxyl sulfate and p-cresyl sulfate is moderate. Besides genetic host factors and environmental factors, also renal function, sex and age influence the serum levels of these co-metabolites.

  1. Purity determination of amphotericin B, colistin sulfate and tobramycin sulfate in a hydrophilic suspension by HPLC.

    Science.gov (United States)

    Pfeifer, Corina; Fassauer, Georg; Gerecke, Hagen; Jira, Thomas; Remane, Yvonne; Frontini, Roberto; Byrne, Jonathan; Reinhardt, Robert

    2015-05-15

    A suspension comprising of the three antibiotic substances amphotericin B, colistin sulfate and tobramycin sulfate is often used in clinical practice for the selective decontamination of the digestive tract of patients in intensive care. Since no detailed procedures, specifications or stability data are available for manufacturing this suspension, there may be discrepancies regarding formulation and stability of suspensions prepared in different pharmacies. The aim of this work is to develop a standardized formulation and to determine its stability under defined storage conditions. This would help guarantee that all patients receive the same preparation, therefore ensuring similar efficacy and improved safety. The first step in this process is to develop the required analytical tools to measure the content and purity of the drug substances in this complex mixture. In this paper, the development and validation of these tools as well as the development of the drug suspension formulation is described. The formulation comprises of Ampho-Moronal(®)-Suspension (Dermapharm) and a buffered, preservated aqueous solution of colistin sulfate and tobramycin sulfate. Two simple, well established high-performance liquid chromatography (HPLC) methods in the European Pharmacopoeia (EP) for impurity profiling of the two active ingredients amphotericin B and colistin sulfate were combined with a newly developed sample extraction procedure for the suspension. Sufficient selectivity and stability-indicating power have been demonstrated. Additionally, a new robust routine method was developed to determine possible degradation products of tobramycin sulfate in the investigated suspension. The specificity, precision, accuracy and linearity of the analytical procedures were demonstrated. The recovery rate was in the range of 90-110%. The precision results for the calculated impurities showed variation coefficients of <10%. The calibration curves were found to be linear with correlation

  2. Sulfation pattern of fucose branches affects the anti-hyperlipidemic activities of fucosylated chondroitin sulfate.

    Science.gov (United States)

    Wu, Nian; Zhang, Yu; Ye, Xingqian; Hu, Yaqin; Ding, Tian; Chen, Shiguo

    2016-08-20

    Fucosylated chondroitin sulfates (fCSs) are glycosaminoglycans extracted from sea cucumbers, consisting of chondroitin sulfate E (CSE) backbones and sulfated fucose branches. The biological properties of fCSs could be affected by the sulfation pattern of their fucose branches. In the present study, two fCSs were isolated from sea cucumbers Isostichopus badionotus (fCS-Ib) and Pearsonothuria graeffei (fCS-Pg). Their monosaccharide compositions of glucuronic acid (GlcA), N-acetylgalactosamine (GalNAc), fucose (Fuc) and sulfate were at similar molar ratio with 1.0/0.7/0.9/3.1 for fCS-Ib and 1.0/0.8/1.5/2.6 for fCS-Pg. The two fCSs have different sulfation patterns on their fucose branches, fCS-Pg with 3,4-O-disulfation while fCS-Ib with 2,4-O-disulfation. Their antihyperlipidemic effects were compared using a high-fat high-fructose diet (HFFD)-fed C57BL/6J mice model. Both fCS-Ib and fCS-Pg had significant effects on lipid profile improvement, liver protection, blood glucose diminution and hepatic glycogen synthesis. Specifically, fCS-Pg with 3,4-O-disulfation fucose branches was more effective in reduction of blood cholesterol (TC), low density lipoprotein (LDL) and atherogenic index (AI). Our results indicate that both fCSs, especially fCS-Pg, could be used as a potential anti-hyperlipidemic drug.

  3. The preparation and antioxidant activity of glucosamine sulfate

    Institute of Scientific and Technical Information of China (English)

    XING Ronge; LIU Song; WANG Lin; CAI Shengbao; YU Huahua; FENG Jinhua; LI Pengcheng

    2009-01-01

    Glucosamine sulfate was prepared from glucosamine hydrochloride that was produced by acidic hydrolysis of chitin by ion-exchange method. Optical rotation and elemental analysis characterized the degree of its purity. In addition, the antioxidant potency of chitosan derivative-glucosamine sulfate was investigated in various established in vitro systems, such as superoxide (O(2))/hydroxyl (·OH) radicals scavenging, reducing power, iron ion chelating. The following results are obtained: first, glucosamine sulfate had pronounced scavenging effect on superoxide radical. For example the O(2) scavenging activity of glucosamine sulfate was 92.11% at 0.8 mg/mL. Second, the ·OH scavenging activity of glucosamine sulfate was also strong, and was about 50% at 3.2 mg/mL Third, the reducing power of glucosamine sulfate was more pronounced. The reducing power of glucosamine sulfate was 0.643 at 0.75 mg/mL.However, its potency for ferrous ion chelating was weak. Furthermore, except for ferrous ion chelating potency, the scavenging rate of radical and reducing power of glucosamine sulfate were concentration-dependent and increased with their increasing concentrations, but its ferrous ion chelating potency decreased with the increasing concentration. The multiple antioxidant activities of glucosamine sulfate were evidents of reducing power and superoxide/hydroxyl radicals scavenging ability. These in vitro results suggest the possibility that glucosamine sulfate could be used effectively as an ingredient in health or functional food, to alleviate oxidative stress.

  4. The preparation and antioxidant activity of glucosamine sulfate

    Science.gov (United States)

    Xing, Ronge; Liu, Song; Wang, Lin; Cai, Shengbao; Yu, Huahua; Feng, Jinhua; Li, Pengcheng

    2009-05-01

    Glucosamine sulfate was prepared from glucosamine hydrochloride that was produced by acidic hydrolysis of chitin by ion-exchange method. Optical rotation and elemental analysis characterized the degree of its purity. In addition, the antioxidant potency of chitosan derivative-glucosamine sulfate was investigated in various established in vitro systems, such as superoxide (O{2/-})/hydroxyl (·OH) radicals scavenging, reducing power, iron ion chelating. The following results are obtained: first, glucosamine sulfate had pronounced scavenging effect on superoxide radical. For example the O{2/-} scavenging activity of glucosamine sulfate was 92.11% at 0.8 mg/mL. Second, the ·OH scavenging activity of glucosamine sulfate was also strong, and was about 50% at 3.2 mg/mL. Third, the reducing power of glucosamine sulfate was more pronounced. The reducing power of glucosamine sulfate was 0.643 at 0.75 mg/mL. However, its potency for ferrous ion chelating was weak. Furthermore, except for ferrous ion chelating potency, the scavenging rate of radical and reducing power of glucosamine sulfate were concentration-dependent and increased with their increasing concentrations, but its ferrous ion chelating potency decreased with the increasing concentration. The multiple antioxidant activities of glucosamine sulfate were evidents of reducing power and superoxide/hydroxyl radicals scavenging ability. These in vitro results suggest the possibility that glucosamine sulfate could be used effectively as an ingredient in health or functional food, to alleviate oxidative stress.

  5. Ligand placement based on prior structures: the guided ligand-replacement method

    Energy Technology Data Exchange (ETDEWEB)

    Klei, Herbert E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bristol-Myers Squibb, Princeton, NJ 08543-4000 (United States); Moriarty, Nigel W., E-mail: nwmoriarty@lbl.gov; Echols, Nathaniel [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Terwilliger, Thomas C. [Los Alamos National Laboratory, Los Alamos, NM 87545-0001 (United States); Baldwin, Eric T. [Bristol-Myers Squibb, Princeton, NJ 08543-4000 (United States); Natural Discovery LLC, Princeton, NJ 08542-0096 (United States); Pokross, Matt; Posy, Shana [Bristol-Myers Squibb, Princeton, NJ 08543-4000 (United States); Adams, Paul D. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); University of California at Berkeley, Berkeley, CA 94720-1762 (United States)

    2014-01-01

    A new module, Guided Ligand Replacement (GLR), has been developed in Phenix to increase the ease and success rate of ligand placement when prior protein-ligand complexes are available. The process of iterative structure-based drug design involves the X-ray crystal structure determination of upwards of 100 ligands with the same general scaffold (i.e. chemotype) complexed with very similar, if not identical, protein targets. In conjunction with insights from computational models and assays, this collection of crystal structures is analyzed to improve potency, to achieve better selectivity and to reduce liabilities such as absorption, distribution, metabolism, excretion and toxicology. Current methods for modeling ligands into electron-density maps typically do not utilize information on how similar ligands bound in related structures. Even if the electron density is of sufficient quality and resolution to allow de novo placement, the process can take considerable time as the size, complexity and torsional degrees of freedom of the ligands increase. A new module, Guided Ligand Replacement (GLR), was developed in Phenix to increase the ease and success rate of ligand placement when prior protein–ligand complexes are available. At the heart of GLR is an algorithm based on graph theory that associates atoms in the target ligand with analogous atoms in the reference ligand. Based on this correspondence, a set of coordinates is generated for the target ligand. GLR is especially useful in two situations: (i) modeling a series of large, flexible, complicated or macrocyclic ligands in successive structures and (ii) modeling ligands as part of a refinement pipeline that can automatically select a reference structure. Even in those cases for which no reference structure is available, if there are multiple copies of the bound ligand per asymmetric unit GLR offers an efficient way to complete the model after the first ligand has been placed. In all of these applications, GLR

  6. Inactivation of thrombin by a fucosylated chondroitin sulfate from echinoderm.

    Science.gov (United States)

    Mourão, P A; Boisson-Vidal, C; Tapon-Bretaudière, J; Drouet, B; Bros, A; Fischer, A

    2001-04-15

    A polysaccharide extracted from the sea cucumber body wall has the same backbone structure as the mammalian chondroitin sulfate, but some of the glucuronic acid residues display sulfated fucose branches. These branches confer high anticoagulant activity to the polysaccharide. Since the sea cucumber chondroitin sulfate has analogy in structure with mammalian glycosaminoglycans and sulfated fucans from brown algae, we compared its anticoagulant action with that of heparin and of a homopolymeric sulfated fucan with approximately the same level of sulfation as the sulfated fucose branches found in the sea cucumber polysaccharide. These various compounds differ not only in their anticoagulant potencies but also in the mechanisms of thrombin inhibition. Fucosylated chondroitin sulfate, like heparin, requires antithrombin or heparin cofactor II for thrombin inhibition. Sulfated fucans from brown algae have an antithrombin effect mediated by antithrombin and heparin cofactor II, plus a direct antithrombin effect more pronounced for some fractions. But even in the case of these two polysaccharides, we observed some differences. In contrast with heparin, total inhibition of thrombin in the presence of antithrombin is not achieved with fucosylated chondroitin sulfate, possibly reflecting a less specific interaction. Fucosylated chondroitin sulfate is able to inhibit thrombin generation after stimulation by both contact-activated and thromboplastin-activated systems. It delayed only the contact-induced thrombin generation, as expected for an anticoagulant without direct thrombin inhibition. Overall, the specific spatial array of the sulfated fucose branches in the fucosylated chondroitin sulfate not only confer high anticoagulant activity to the polysaccharide but also determine differences in the way it inhibits thrombin.

  7. Lacrimal gland development and Fgf10-Fgfr2b signaling are controlled by 2-O- and 6-O-sulfated heparan sulfate

    NARCIS (Netherlands)

    Qu, X.; Carbe, C.; Tao, C.; Powers, A.; Lawrence, R.; Kuppevelt, A.H.M.S.M. van; Cardoso, W.V.; Grobe, K.; Esko, J.D.; Zhang, X.

    2011-01-01

    Heparan sulfate, an extensively sulfated glycosaminoglycan abundant on cell surface proteoglycans, regulates intercellular signaling through its binding to various growth factors and receptors. In the lacrimal gland, branching morphogenesis depends on the interaction of heparan sulfate with Fgf10-Fg

  8. EXAFS study of mercury(II) sorption to Fe- and Al-(hydr)oxides - II. Effects of chloride and sulfate

    Science.gov (United States)

    Kim, C.S.; Rytuba, J.J.; Brown, Gordon E.

    2004-01-01

    Common complexing ligands such as chloride and sulfate can significantly impact the sorption of Hg(II) to particle surfaces in aqueous environmental systems. To examine the effects of these ligands on Hg(II) sorption to mineral sorbents, macroscopic Hg(II) uptake measurements were conducted at pH 6 and [Hg]i=0.5 mM on goethite (??-FeOOH), ??-alumina (??-Al2O3), and bayerite (??-Al(OH)3) in the presence of chloride or sulfate, and the sorption products were characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. The presence of chloride resulted in reduced uptake of Hg(II) on all three substrates over the Cl- concentration ([Cl-]) range 10-5 to 10-2 M, lowering Hg surface coverages on goethite, ??-alumina, and bayerite from 0.42 to 0.07 ??mol/m2, 0.06 to 0.006 ??mol/m2, and 0.55 to 0.39 ??mol/m2 ([Cl -]=10-5 to 10-3 M only), respectively. This reduction in Hg(II) uptake is primarily a result of the formation of stable, nonsorbing aqueous HgCl2 complexes in solution, limiting the amount of free Hg(II) available to sorb. At higher [Cl-] beam reduction of Hg(II) to Hg(I) was observed, resulting in the possible formation of aqueous Hg2Cl2 species and the precipitation of calomel, Hg 2Cl2(s). The presence of sulfate caused enhanced Hg(II) uptake over the sulfate concentration ([SO42-]) range 10-5 to 0.9 M, increasing Hg surface coverages on goethite, ??-alumina, and bayerite from 0.39 to 0.45 ??mol/m2, 0.11 to 0.38 ??mol/m2, and 0.36 to 3.33 ??mol/m2, respectively. This effect is likely due to the direct sorption or accumulation of sulfate ions at the substrate interface, effectively reducing the positive surface charge that electrostatically inhibits Hg(II) sorption. Spectroscopic evidence for ternary surface complexation was observed in isolated cases, specifically in the Hg-goethite-sulfate system at high [SO42-] and in the Hg-goethite-chloride system. ?? 2003 Elsevier Inc. All rights reserved.

  9. Utilization of sulfate additives in biomass combustion: fundamental and modeling aspects

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Grell, Morten Nedergaard;

    2013-01-01

    Sulfates, such as ammonium sulfate, aluminum sulfate and ferric sulfate, are effective additives for converting the alkali chlorides released from biomass combustion to the less harmful alkali sulfates. Optimization of the use of these additives requires knowledge on their decomposition rate...... and product distribution under high temperature conditions. In the present work, the decomposition of ammonium sulfate, aluminum sulfate and ferric sulfate was studied respectively in a fast-heating rate thermogravimetric analyzer for deriving a kinetic model to describe the process. The yields of SO2 and SO3...... of different sulfates indicated that ammonium sulfate has clearly strongest sulfation power towards KCl at temperatures below 800oC, whereas the sulfation power of ferric and aluminum sulfates exceeds clearly that of ammonium sulfate between 900 and 1000oC. However, feeding gaseous SO3 was found to be most...

  10. Effects of sulfate deprivation on the production of chondroitin/dermatan sulfate by cultures of skin fibroblasts from normal and diabetic individuals

    Energy Technology Data Exchange (ETDEWEB)

    Silbert, C.K.; Humphries, D.E.; Palmer, M.E.; Silbert, J.E. (Veterans Administration Outpatient Clinic, Boston, MA (USA))

    1991-02-15

    Human skin fibroblast monolayer cultures from two normal men, three Type I diabetic men, and one Type I diabetic woman were incubated with (3H)glucosamine in the presence of diminished concentrations of sulfate. Although total synthesis of (3H)chondroitin/dermatan glycosaminoglycans varied somewhat between cell lines, glycosaminoglycan production was not affected within any line when sulfate levels were decreased from 0.3 mM to 0.06 mM to 0.01 mM to 0 added sulfate. Lowering of sulfate concentrations resulted in diminished sulfation of chondroitin/dermatan in a progressive manner, so that overall sulfation dropped to as low as 19% for one of the lines. Sulfation of chondroitin to form chondroitin 4-sulfate and chondroitin 6-sulfate was progressively and equally affected by decreasing the sulfate concentration in the culture medium. However, sulfation to form dermatan sulfate was preserved to a greater degree, so that the relative proportion of dermatan sulfate to chondroitin sulfate increased. Essentially all the nonsulfated residues were susceptible to chondroitin AC lyase, indicating that little epimerization of glucuronic acid residues to iduronic acid had occurred in the absence of sulfation. These results confirm the previously described dependency of glucuronic/iduronic epimerization on sulfation, and indicate that sulfation of the iduronic acid-containing disaccharide residues of dermatan can take place with sulfate concentrations lower than those needed for 6-sulfation and 4-sulfation of the glucuronic acid-containing disaccharide residues of chondroitin. There were considerable differences among the six fibroblast lines in susceptibility to low sulfate medium and in the proportion of chondroitin 6-sulfate, chondroitin 4-sulfate, and dermatan sulfate. However, there was no pattern of differences between normals and diabetics.

  11. CB receptor ligands from plants.

    Science.gov (United States)

    Woelkart, Karin; Salo-Ahen, Outi M H; Bauer, Rudolf

    2008-01-01

    Advances in understanding the physiology and pharmacology of the endogenous cannabinoid system have potentiated the interest of cannabinoid receptors as potential therapeutic targets. Cannabinoids have been shown to modulate a variety of immune cell functions and have therapeutic implications on central nervous system (CNS) inflammation, chronic inflammatory conditions such as arthritis, and may be therapeutically useful in treating autoimmune conditions such as multiple sclerosis. Many of these drug effects occur through cannabinoid receptor signalling mechanisms and the modulation of cytokines and other gene products. Further, endocannabinoids have been found to have many physiological and patho-physiological functions, including mood alteration and analgesia, control of energy balance, gut motility, motor and co-ordination activities, as well as alleviation of neurological, psychiatric and eating disorders. Plants offer a wide range of chemical diversity and have been a growing domain in the search for effective cannabinoid ligands. Cannabis sativa L. with the known plant cannabinoid, Delta(9-)tetrahydrocannabinol (THC) and Echinacea species with the cannabinoid (CB) receptor-binding lipophilic alkamides are the best known herbal cannabimimetics. This review focuses on the state of the art in CB ligands from plants, as well their possible therapeutic and immunomodulatory effects.

  12. Ligand photo-isomerization triggers conformational changes in iGluR2 ligand binding domain.

    Directory of Open Access Journals (Sweden)

    Tino Wolter

    Full Text Available Neurological glutamate receptors bind a variety of artificial ligands, both agonistic and antagonistic, in addition to glutamate. Studying their small molecule binding properties increases our understanding of the central nervous system and a variety of associated pathologies. The large, oligomeric multidomain membrane protein contains a large and flexible ligand binding domains which undergoes large conformational changes upon binding different ligands. A recent application of glutamate receptors is their activation or inhibition via photo-switchable ligands, making them key systems in the emerging field of optochemical genetics. In this work, we present a theoretical study on the binding mode and complex stability of a novel photo-switchable ligand, ATA-3, which reversibly binds to glutamate receptors ligand binding domains (LBDs. We propose two possible binding modes for this ligand based on flexible ligand docking calculations and show one of them to be analogues to the binding mode of a similar ligand, 2-BnTetAMPA. In long MD simulations, it was observed that transitions between both binding poses involve breaking and reforming the T686-E402 protein hydrogen bond. Simulating the ligand photo-isomerization process shows that the two possible configurations of the ligand azo-group have markedly different complex stabilities and equilibrium binding modes. A strong but slow protein response is observed after ligand configuration changes. This provides a microscopic foundation for the observed difference in ligand activity upon light-switching.

  13. Sulfated fucan as support for antibiotic immobilization.

    Science.gov (United States)

    Araújo, P M; Oliveira, G B; Córdula, C R; Leite, E L; Carvalho Jr, L B; Silva, M P C

    2004-03-01

    Xylofucoglucuronan from Spatoglossum schröederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml) was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide methiodide (20 mg in 2 ml), under stirring for 1 h at 25 masculine C and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml) was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C=O at 1647.9 and 1700.7 cm(-1)) and to amide (C-NH2) groups (1662.8 and 1714.0 cm(-1)). Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schröederi.

  14. Sulfated fucan as support for antibiotic immobilization

    Directory of Open Access Journals (Sweden)

    Araújo P.M.

    2004-01-01

    Full Text Available Xylofucoglucuronan from Spatoglossum schröederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propylcarbodiimide methiodide (20 mg in 2 ml, under stirring for 1 h at 25ºC and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C = O at 1647.9 and 1700.7 cm-1 and to amide (CÝ-NH2 groups (1662.8 and 1714.0 cm-1. Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schröederi.

  15. Synthesis and characterization of novel cellulose ether sulfates.

    Science.gov (United States)

    Rohowsky, Juta; Heise, Katja; Fischer, Steffen; Hettrich, Kay

    2016-05-20

    The synthesis and characterization of novel cellulose sulfate derivatives was reported. Various cellulose ethers were prepared in a homogeneous reaction with common sulfating agents. The received product possess different properties in dependence on the reaction conditions like sulfating agent, solvent, reaction time and reaction temperature. The cellulose ether sulfates are all soluble in water, they rheological behavior could be determined by viscosity measurements and the determination of the sulfur content by elemental analysis lead to a resulting degree of substitution ascribed to sulfate groups (DSSul) of the product. A wide range of products from DSSul 0.1 to DSSul 2.7 will be obtained. Furthermore the cellulose sulfate ethers could be characterized by Raman spectroscopy.

  16. Measurement of protein-ligand complex formation.

    Science.gov (United States)

    Lowe, Peter N; Vaughan, Cara K; Daviter, Tina

    2013-01-01

    Experimental approaches to detect, measure, and quantify protein-ligand binding, along with their theoretical bases, are described. A range of methods for detection of protein-ligand interactions is summarized. Specific protocols are provided for a nonequilibrium procedure pull-down assay, for an equilibrium direct binding method and its modification into a competition-based measurement and for steady-state measurements based on the effects of ligands on enzyme catalysis.

  17. Synthesis, crystal structure and characterization of new biologically active Cu(II) complexes with ligand derived from N-substituted sulfonamide

    Indian Academy of Sciences (India)

    ADRIANA CORINA HANGAN; ALEXANDRU TURZA; ROXANA LIANA STAN; BOGDAN SEVASTRE; EMÖKE PÁLL; SÎNZIANA CETEAN; LUMINI¸TA SIMONA OPREAN

    2016-05-01

    A new N-sulfonamide ligand (HL1= N-(5-(4-methoxyphenyl)-[1,3,4]–thiadiazole–2-yl)-toluenesulfonamide)and two Cu(II) complexes, $[Cu(L1)­_{2}(py)_{2}]$ (C1) and $[Cu(L2)_{2}(py)_{2}(H_{2}O)]$ (C2) (HL2 = N-(5-(4-methylphenyl)-[1,3,4]–thiadiazole–2-yl)-benzenesulfonamide) were synthesized. The X-ray crystal structuresof the complexes were determined. In the complex C1, the Cu(II) ion is four-coordinated, forming a $CuN_{4}$ chromophore and in the complex C2, the Cu(II) ion is five-coordinated, forming a $CuN_{4}O$ chromophore. Theligand acts as monodentate, coordinating the Cu(II) ion through a single $N_{thiadiazole}$ atom. The molecules fromthe reaction medium (pyridine and water) are also involved in the coordination of the Cu(II) ion. The complexesC1 and C2 are square-planar and a slightly distorted square pyramidal, respectively. The compounds werecharacterized by FT-IR, electronic, EPR spectroscopic and magnetic methods. The nuclease binding activitystudies of the synthesized complexes confirm their capacity to cleave the DNA molecule. The cytotoxicitystudies were carried out on melanoma cell line WM35 which confirm that both compounds inhibit the growthof these cells. They have a higher activity compared to a platinum drug, carboplatin.

  18. Synthesis, Crystal Structure and Luminescent Properties of a Novel Zinc(Ⅱ) Complex of N-Acetyl-L-glutamic Acid and Imidazole Ligands

    Institute of Scientific and Technical Information of China (English)

    CHENG Meng-Qi; MA Lu-Fang; WANG Li-Ya; WANG Jian-Ge

    2006-01-01

    A novel complex (Zn(Im)2(A-glu)·0.5H2O (Im = imidazole, A-glu = N-acetyl- L-glutamic acid) has been synthesized from the reaction of A-glu with Zn(CH3COO)2(2H2O in the presence of Im at 65 ℃, and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in tetragonal, space group P43212 with a = b = 8.9078(6), c = 43.458(6) (A), C26H36N10O11Zn2, Mr = 795.39, V = 3448.3(6) (A)3, Dc = 1.532 g/cm3, Z = 4, μ(MoK() = 1.461 mm(1, F(000) = 1640, the final R = 0.0453 and wR = 0.0992. X-ray analysis reveals that the crystal structure is constructed by mixed ligands. A-glu adopts the bis-monodentate coordination mode linking two adjacent metal ions to form a one-dimensional chain. Zinc(Ⅱ) ions are four-coordinated with a distorted tetrahedral geometry. Luminescent properties of the complex have been inves- tigated.

  19. 1D zigzag chain and 0D monomer Cd(II)/Zn(II) compounds based on flexible phenylenediacetic ligand: Synthesis, crystal structures and fluorescent properties

    Science.gov (United States)

    Yang, Fang; Ren, Yixia; Li, Dongsheng; Fu, Feng; Qi, Guangcai; Wang, Yaoyu

    2008-12-01

    Three novel Cd(II)/Zn(II) compounds, [Cd 2(poda) 2(phen) 3(H 2O)] n· nEtOH·3 nH 2O (1), [Zn(poda) 2(bpy)(H 2O)] n(2) and [Zn(Hpoda) 2(bpy)] (3) (H 2poda = 1,2-phenylenediacetic acid, phen = 1,10-phenanthroline, bpy = 2,2'-bipyridyl), have been synthesized and characterized by IR, TG, fluorescent spectrum and single-crystal X-ray diffraction techniques. In 1, poda 2- anions link the adjacent Cd(II) centers to generate a 1D zigzag chain. Furthermore, an unprecedented four-footed "8-shaped" mixed water-ethanol (H 2O) 6(C 2H 5OH) 2 cluster connects four double chains based on 1D zigzag chain into 3D supramolecular architecture. By bis(chelate-monodentate) fashion of poda 2- ligand, compound 2 exhibits 1D zigzag chains, which forming a dense zipper-like 2D structure via strong π-π stacking interactions. Differed from 1 and 2, compound 3 has a mononuclear motif, and displays a 3D 6-connected α-Po net hydrogen-bonded topology. The structure-related solid-state fluorescence spectra of compounds 1 and 2 have been determined.

  20. Synthesis, characterization and magnetic property of a succinate bridged 1D coordination polymer of cobalt(II) containing benzidine as end-capping ligand

    Science.gov (United States)

    Roy, Subhasis; Choubey, Somnath; Khan, Sumitava; Bhar, Kishalay; Ribas, Joan; Ghosh, Barindra Kumar

    2014-03-01

    A new bis(monodentate) succinate bridged 1D coordination polymer [Co(bnzd)2(μ-suc)(OH2)2]nṡ(H2O)n (1) (bnzd = benzidine; suc = succinate dianion) has been isolated using a one-pot reaction of the building components, and characterized structurally and magneto-structurally. Single crystal X-ray diffraction measurement reveals that each cobalt(II) center adopts an octahedral geometry with a CoN2O4 chromophore coordinated by two N atoms of two bnzd ligands, two O atoms of two water molecules and two O atoms of two suc units. In crystalline state, individual units of 1 self-assemble through cooperative N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π interactions affording a 3D network structure. Variable-temperature magnetic susceptibility measurement of 1 in the 2-300 K temperature range shows weak antiferromagnetic coupling among the adjacent cobalt(II) centers presumably due to long bridging arm of the dicarboxylate.

  1. Transition metal coordination polymers with polycarboxylic acid as bridging ligands: Synthesis and structure characterization of [Fe(μ4-bta)0.5(phen)(OH)]n

    Institute of Scientific and Technical Information of China (English)

    XU; Jiqing; CHU; Deqing; YU; Jiehui; WANG; Tiegang; TANG; A

    2004-01-01

    A new 2D (two-dimensional) coordination polymer, [Fe(μ4-bta)0.5(phen)(OH)]n (1), has been hydrothermally synthesized with FeCl3·6H2O, Na4bta (H4bta = 1,2,4,5-benzentetra- carboxylic acid), 1,10-phen (1,10-phenanthroline) and H2O as raw materials. The crystals of the compound belong to monoclinic P21/n space group, a = 1.0129(2) nm, b = 0.9265(2) nm, c = 1.5696(3) nm,β = 91.37(3) o, V = 1.4721(5) nm3, Z = 3, final R1 = 0.0292, Wr2 = 0.0798 for 2572 [I > 2σ (I )] observed reflections. The result of structure determination shows that in the compound each bta ligand is connected with four FeIII, forming a new μ4-coordination mode. Four deprotonated carboxylic groups of bta link to FeIII ions alternatively through monodentate and bidentate coordination fashion, constructing 2D layer network. The measurement of variable temperature magnetic susceptibility indicates that there exist antiferromagnetic interactions between FeIII ions in the compound. The TGA spectrum displays relatively fine thermal stability of the compound. In addition, IR and UV-Vis spectra of compound 1 have also been measured.

  2. Transition metal coordination polymers with polycarboxylic acid as bridging ligands:Synthesis and structure characterization of [Fe(μ4-bta)0.5(phen)(OH)]n

    Institute of Scientific and Technical Information of China (English)

    XU Jiqing; CHU Deqing; YU Jiehui; WANG Tiegang; TANG Aoqing

    2004-01-01

    A new 2D (two-dimensional) coordination polymer, [Fe(μ4-bta)0.5(phen)(OH)]n (1), has been hydrothermally synthesized with FeCl3·6H2O, Na4bta (H4bta = 1,2,4,5-benzentetra- carboxylic acid), 1,10-phen (1,10-phenanthroline) and H2O as raw materials. The crystals of the compound belong to monoclinic P21/n space group, a = 1.0129(2) nm, b = 0.9265(2) nm, c = 1.5696(3) nm,β = 91.37(3) o, V = 1.4721(5) nm3, Z = 3, final R1 = 0.0292, Wr2 = 0.0798 for 2572 [I > 2σ (I )] observed reflections. The result of structure determination shows that in the compound each bta ligand is connected with four FeIII, forming a new μ4-coordination mode. Four deprotonated carboxylic groups of bta link to FeIII ions alternatively through monodentate and bidentate coordination fashion, constructing 2D layer network. The measurement of variable temperature magnetic susceptibility indicates that there exist antiferromagnetic interactions between FeIII ions in the compound. The TGA spectrum displays relatively fine thermal stability of the compound. In addition, IR and UV-Vis spectra of compound 1 have also been measured.

  3. The Suramin Derivative NF449 Interacts with the 5-fold Vertex of the Enterovirus A71 Capsid to Prevent Virus Attachment to PSGL-1 and Heparan Sulfate.

    Directory of Open Access Journals (Sweden)

    Yorihiro Nishimura

    2015-10-01

    Full Text Available NF449, a sulfated compound derived from the antiparasitic drug suramin, was previously reported to inhibit infection by enterovirus A71 (EV-A71. In the current work, we found that NF449 inhibits virus attachment to target cells, and specifically blocks virus interaction with two identified receptors--the P-selectin ligand, PSGL-1, and heparan sulfate glycosaminoglycan--with no effect on virus binding to a third receptor, the scavenger receptor SCARB2. We also examined a number of commercially available suramin analogues, and newly synthesized derivatives of NF449; among these, NF110 and NM16, like NF449, inhibited virus attachment at submicromolar concentrations. PSGL-1 and heparan sulfate, but not SCARB2, are both sulfated molecules, and their interaction with EV-A71 is thought to involve positively charged capsid residues, including a conserved lysine at VP1-244, near the icosahedral 5-fold vertex. We found that mutation of VP1-244 resulted in resistance to NF449, suggesting that this residue is involved in NF449 interaction with the virus capsid. Consistent with this idea, NF449 and NF110 prevented virus interaction with monoclonal antibody MA28-7, which specifically recognizes an epitope overlapping VP1-244 at the 5-fold vertex. Based on these observations we propose that NF449 and related compounds compete with sulfated receptor molecules for a binding site at the 5-fold vertex of the EV-A71 capsid.

  4. Chemical leukoderma induced by dimethyl sulfate*

    Science.gov (United States)

    Gozali, Maya Valeska; Zhang, Jia-an; Yi, Fei; Zhou, Bing-rong; Luo, Dan

    2016-01-01

    Chemical leukoderma occurs due to the toxic effect of a variety of chemical agents. Mechanisms include either destruction or inhibition of melanocytes. We report two male patients (36 and 51 years old) who presented with multiple hypopigmented macules and patches on the neck, wrist, and legs after exposure to dimethyl sulfate in a chemical industry. Physical examination revealed irregular depigmentation macules with sharp edges and clear hyperpigmentation around the lesions. History of repeated exposure to a chemical agent can help the clinical diagnosis of chemical leukoderma. This diagnosis is very important for prognosis and therapeutic management of the disease.

  5. New Bioactive Alkyl Sulfates from Mediterranean Tunicates

    Directory of Open Access Journals (Sweden)

    Marialuisa Menna

    2012-10-01

    Full Text Available Chemical investigation of two species of marine ascidians, Aplidium elegans and Ciona edwardsii, collected in Mediterranean area, led to isolation of a series of alkyl sulfates (compounds 1–5 including three new molecules 1–3. Structures of the new metabolites have been elucidated by spectroscopic analysis. Based on previously reported cytotoxic activity of these type of molecules, compounds 1–3 have been tested for their effects on the growth of two cell lines, J774A.1 (BALB/c murine macrophages and C6 (rat glioma in vitro. Compounds 1 and 2 induced selective concentration-dependent mortality on J774A.1 cells.

  6. Sulfation patterns determine cellular internalization of heparin-like polysaccharides

    OpenAIRE

    Raman, Karthik; Mencio, Caitlin; Desai, Umesh R.; Kuberan, Balagurunathan

    2013-01-01

    Heparin is a highly sulfated polysaccharide which serves biologically relevant roles as an anticoagulant and anti-cancer agent. While it is well known that modification of heparin’s sulfation pattern can drastically influence its ability to bind growth factors and other extracellular molecules, very little is known about the cellular uptake of heparin and the role sulfation patterns serve in affecting its internalization. In this study, we chemically synthesized several fluorescently-labeled ...

  7. Glycosaminoglycan modifications in Duchenne muscular dystrophy: specific remodeling of chondroitin sulfate/dermatan sulfate.

    Science.gov (United States)

    Negroni, Elisa; Henault, Emilie; Chevalier, Fabien; Gilbert-Sirieix, Marie; Van Kuppevelt, Toin H; Papy-Garcia, Dulce; Uzan, Georges; Albanese, Patricia

    2014-08-01

    Widespread skeletal muscle degeneration and impaired regeneration lead to progressive muscle weakness and premature death in patients with Duchenne muscular dystrophy (DMD). Dystrophic muscles are progressively replaced by nonfunctional tissue because of exhaustion of muscle precursor cells and excessive accumulation of extracellular matrix (ECM). Sulfated glycosaminoglycans (GAGs) are components of the ECM and are increasingly implicated in the regulation of biologic processes, but their possible role in the progression of DMD pathology is not understood. In the present study, we performed immunohistochemical and biochemical analyses of endogenous GAGs in skeletal muscle biopsies of 10 DMD patients and 11 healthy individuals (controls). Immunostaining targeted to specific GAG species showed greater deposition of chondroitin sulfate (CS)/dermatan (DS) sulfate in DMD patient biopsies versus control biopsies. The selective accumulation of CS/DS in DMD biopsies was confirmed by biochemical quantification assay. In addition, high-performance liquid chromatography analysis demonstrated a modification of the sulfation pattern of CS/DS disaccharide units in DMD muscles. In conclusion, our data open up a new path of investigation and suggest that GAGs could represent a new and original therapeutic target for improving the success of gene or cell therapy for the treatment of muscular dystrophies.

  8. Sulfation of heparan sulfate associated with amyloid-beta plaques in patients with Alzheimer's disease.

    NARCIS (Netherlands)

    Bruinsma, I.B.; Riet, L. te; Gevers, T.; Dam, G.B. ten; Kuppevelt, A.H.M.S.M. van; David, G.; Kusters, B.; Waal, R.M.W. de; Verbeek, M.M.

    2010-01-01

    Alzheimer's disease (AD) is characterized by pathological lesions such as amyloid-beta (Abeta) plaques and cerebral amyloid angiopathy. Both these lesions consist mainly of aggregated Abeta protein and this aggregation is affected by macromolecules such as heparan sulfate (HS) proteoglycans.

  9. Inter vs. intraglycosidic acetal linkages control sulfation pattern in semi-synthetic chondroitin sulfate.

    Science.gov (United States)

    Laezza, Antonio; De Castro, Cristina; Parrilli, Michelangelo; Bedini, Emiliano

    2014-11-04

    Microbial-sourced unsulfated chondroitin could be converted into chondroitin sulfate (CS) polysaccharide by a multi-step strategy relying upon benzylidenation and acetylation reactions as key-steps for its regioselective protection. By conducting the two reactions one- or two-pots, CSs with different sulfation patterns could be obtained at the end of the semi-synthesis. In particular, a CS polysaccharide possessing sulfate groups randomly distributed between positions 4 and 6 of N-acetyl-galactosamine (GalNAc) units could be obtained through the two-pots route, whereas the one-pot pathway allowed an additional sulfation at position 3 of some glucuronic acid (GlcA) units. This difference was ascribed to the stabilization of a labile interglycosidic benzylidene acetal involving positions O-3 and O-6 of some GlcA and GalNAc, respectively, when the benzylidene-acetylation reactions were conducted in a one-pot fashion. Isolation and characterization of a polysaccharide intermediate showing interglycosidic acetal moieties was accomplished.

  10. Role of cellular heparan sulfate proteoglycans in infection of human adenovirus serotype 3 and 35.

    Directory of Open Access Journals (Sweden)

    Sebastian Tuve

    2008-10-01

    Full Text Available Species B human adenoviruses (Ads are increasingly associated with outbreaks of acute respiratory disease in U.S. military personnel and civil population. The initial interaction of Ads with cellular attachment receptors on host cells is via Ad fiber knob protein. Our previous studies showed that one species B Ad receptor is the complement receptor CD46 that is used by serotypes 11, 16, 21, 35, and 50 but not by serotypes 3, 7, and 14. In this study, we attempted to identify yet-unknown species B cellular receptors. For this purpose we used recombinant Ad3 and Ad35 fiber knobs in high-throughput receptor screening methods including mass spectrometry analysis and glycan arrays. Surprisingly, we found that the main interacting surface molecules of Ad3 fiber knob are cellular heparan sulfate proteoglycans (HSPGs. We subsequently found that HSPGs acted as low-affinity co-receptors for Ad3 but did not represent the main receptor of this serotype. Our study also revealed a new CD46-independent infection pathway of Ad35. This Ad35 infection mechanism is mediated by cellular HSPGs. The interaction of Ad35 with HSPGs is not via fiber knob, whereas Ad3 interacts with HSPGs via fiber knob. Both Ad3 and Ad35 interacted specifically with the sulfated regions within HSPGs that have also been implicated in binding physiologic ligands. In conclusion, our findings show that Ad3 and Ad35 directly utilize HSPGs as co-receptors for infection. Our data suggest that adenoviruses evolved to simulate the presence of physiologic HSPG ligands in order to increase infection.

  11. Synthesis and characterization of fac-[M(CO)3(P)(OO)] and cis-trans-[M(CO)2(P)2(OO)] complexes (M = Re, (99m)Tc) with acetylacetone and curcumin as OO donor bidentate ligands.

    Science.gov (United States)

    Triantis, Charalampos; Tsotakos, Theodoros; Tsoukalas, Charalampos; Sagnou, Marina; Raptopoulou, Catherine; Terzis, Aris; Psycharis, Vassilis; Pelecanou, Maria; Pirmettis, Ioannis; Papadopoulos, Minas

    2013-11-18

    The synthesis and characterization of neutral mixed ligand complexes fac-[M(CO)3(P)(OO)] and cis-trans-[M(CO)2(P)2(OO)] (M = Re, (99m)Tc), with deprotonated acetylacetone or curcumin as the OO donor bidentate ligands and a phosphine (triphenylphosphine or methyldiphenylphosphine) as the monodentate P ligand, is described. The complexes were synthesized through the corresponding fac-[M(CO)3(H2O)(OO)] (M = Re, (99m)Tc) intermediate aqua complex. In the presence of phosphine, replacement of the H2O molecule of the intermediate complex at room temperature generates the neutral tricarbonyl monophosphine fac-[Re(CO)3(P)(OO)] complex, while under reflux conditions further replacement of the trans to the phosphine carbonyl generates the new stable dicarbonyl bisphosphine complex cis-trans-[Re(CO)2(P)2(OO)]. The Re complexes were fully characterized by elemental analysis, spectroscopic methods, and X-ray crystallography showing a distorted octahedral geometry around Re. Both the monophosphine and the bisphosphine complexes of curcumin show selective binding to β-amyloid plaques of Alzheimer's disease. At the (99m)Tc tracer level, the same type of complexes, fac-[(99m)Tc(CO)3(P)(OO)] and cis-trans-[(99m)Tc(CO)2(P)2(OO)], are formed introducing new donor combinations for (99m)Tc(I). Overall, β-diketonate and phosphine constitute a versatile ligand combination for Re(I) and (99m)Tc(I), and the successful employment of the multipotent curcumin as β-diketone provides a solid example of the pharmacological potential of this system.

  12. 平面正方形配合物取代反应的机理和反位效应%Ligand substitution reaction mechanism and trans-effect of square-planar complexes

    Institute of Scientific and Technical Information of China (English)

    于兆文; 张武; 滕洪梅

    2013-01-01

      平面正方形配合物反位效应的起因已经困惑了人们将近一个世纪。作者根据平面正方形配合物取代反应的缔合机理,考虑了配体取代反应进行过程中配体间的排斥作用,分析了最易形成的中间体和过渡态2的空间构型;揭示了反位效应的起因,提出了一种配体排斥理论,从而比较系统和圆满地解释了平面正方形配合物取代反应的反位效应。%The cause of trans-effect for square planar complexes has puzzled people for nearly a century .Based on the fact that the ligand substitution reactions of square-planar complexes re-act by a SN2 mechanism ,the most preferable configurations for the intermediate and transition state 2 were deduced while the repulsions between the ligands in the reaction pathway were considered .Furthermore ,the causes of trans-effect were revealed ,and a new theory---ligand repulsion theory was proposed to illustrate the trans-effect . It was found that as-proposed theory can be well adopted to independently and systematically explain the trans-effect for all kinds of monodentate ligands .

  13. REFINEMENT OF THE CRYSTAL STRUCTURE OF GUANIDINIUM ALUMINUM SULFATE HEXAHYDRATE.

    Science.gov (United States)

    FERROELECTRIC CRYSTALS, * CRYSTAL STRUCTURE ), (*GUANIDINES, CRYSTAL STRUCTURE ), (*ALUMINUM COMPOUNDS, CRYSTAL STRUCTURE ), SULFATES, HYDRATES, X RAY DIFFRACTION, CHROMIUM COMPOUNDS, CRYSTAL LATTICES, CHEMICAL BONDS

  14. Cloud water chemistry and the production of sulfates in clouds

    Science.gov (United States)

    Hegg, D. A.; Hobbs, P. V.

    1981-01-01

    Measurements are presented of the pH and ionic content of water collected in clouds over western Washington and the Los Angeles Basin. Evidence for sulfate production in some of the clouds is presented. Not all of the sulfur in the cloud water was in the form of sulfate. However, the measurements indicate that the production of sulfate in clouds is of considerable significance in the atmosphere. Comparison of field measurements with model results show reasonable agreement and suggest that the production of sulfate in cloud water is a consequence of more than one conversion mechanism.

  15. Theoretical study on the reactivity of sulfate species with hydrocarbons

    Science.gov (United States)

    Ma, Q.; Ellis, G.S.; Amrani, A.; Zhang, T.; Tang, Y.

    2008-01-01

    The abiotic, thermochemically controlled reduction of sulfate to hydrogen sulfide coupled with the oxidation of hydrocarbons, is termed thermochemical sulfate reduction (TSR), and is an important alteration process that affects petroleum accumulations in nature. Although TSR is commonly observed in high-temperature carbonate reservoirs, it has proven difficult to simulate in the laboratory under conditions resembling nature. The present study was designed to evaluate the relative reactivities of various sulfate species in order to provide greater insight into the mechanism of TSR and potentially to fill the gap between laboratory experimental data and geological observations. Accordingly, quantum mechanics density functional theory (DFT) was used to determine the activation energy required to reach a potential transition state for various aqueous systems involving simple hydrocarbons and different sulfate species. The entire reaction process that results in the reduction of sulfate to sulfide is far too complex to be modeled entirely; therefore, we examined what is believed to be the rate limiting step, namely, the reduction of sulfate S(VI) to sulfite S(IV). The results of the study show that water-solvated sulfate anions SO42 - are very stable due to their symmetrical molecular structure and spherical electronic distributions. Consequently, in the absence of catalysis, the reactivity of SO42 - is expected to be extremely low. However, both the protonation of sulfate to form bisulfate anions (HSO4-) and the formation of metal-sulfate contact ion-pairs could effectively destabilize the sulfate molecular structure, thereby making it more reactive. Previous reports of experimental simulations of TSR generally have involved the use of acidic solutions that contain elevated concentrations of HSO4- relative to SO42 -. However, in formation waters typically encountered in petroleum reservoirs, the concentration of HSO4- is likely to be significantly lower than the levels

  16. An Instrument to Measure Aircraft Sulfate Particle Emissions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aerodyne is developing a sulfate detection instrument, based on the Tunable Infrared Laser Differential Absorption Spectrophotometer (TILDAS) technology and...

  17. Sulfate Reduction in Groundwater: Characterization and Applications for Remediation

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Z.; Brusseau, M. L.; Carroll, Kenneth C.; Carreon-Diazconti, C.; Johnson, B.

    2012-06-01

    Sulfate is ubiquitous in groundwater, with both natural and anthropogenic sources. Sulfate reduction reactions play a significant role in mediating redox conditions and biogeochemical processes for subsurface systems. They also serve as the basis for innovative in-situ methods for groundwater remediation. An overview of sulfate reduction in subsurface environments is provided, with a specific focus on implications for groundwater remediation. A case study presenting the results of a pilot-scale ethanol injection test illustrates the advantages and difficulties associated with the use of electron-donor amendments for sulfate remediation.

  18. Basement membrane chondroitin sulfate proteoglycans: localization in adult rat tissues

    DEFF Research Database (Denmark)

    McCarthy, K J; Couchman, J R

    1990-01-01

    Heparan sulfate proteoglycans have been described as the major proteoglycan component of basement membranes. However, previous investigators have also provided evidence for the presence of chondroitin sulfate glycosaminoglycan in these structures. Recently we described the production...... and characterization of core protein-specific monoclonal antibodies (MAb) against a chondroitin sulfate proteoglycan (CSPG) present in Reichert's membrane, a transient extra-embryonic structure of rodents. This CSPG was also demonstrated to be present in adult rat kidney. We report here the tissue distribution...... sulfate proteoglycans previously described....

  19. Controls of Soluble Al in Experimental Acid Sulfate Conditions and Acid Sulfate Soils

    Institute of Scientific and Technical Information of China (English)

    LINCHUXIA; M.D.MELVILLE

    1997-01-01

    The controls of soluble Al concentration were examined in three situations of acid sulfate conditions:1) experimental acid sulfate conditions by addition of varying amounts of Al(OH)3(gibbsite) into a sequence of H2SO4 solutions;2)experimental acid sulfate conditions by addition of the same sequence of H2SO4 solutions into two non-cid sulfacte soil samples with known amounts of acid oxalate extractable Al; and 3) actual acid sulfate soil conditions.The experiment using gibbsite as an Al-bearing mineral showed that increase in the concentration of H2SO4 solution increased the soluble Al concentration,accompanied by a decrease i the solution pH, Increasing amount of gibbsite added to the H2SO4 solutions also increased soluble Al concentration,but resulted in an increase in solution pH.Within the H2SO4 concentration range of 0.0005-0.5mol L-1 and the Al(OH)3 range of 0.01-0.5g(in 25 mL of H2SO4 solutions),the input of H2SO4 had the major control on soluble Al Concentration and pH .The availability of Al(OH)3,however,was responsible for the spread fo the various sample points,with a tendency that the samples containing more gibbsite had a higher soluble Al concentration than those containing less gibbsite at equivalent pH levels.The experimental results from treatment of soil samples with H2SO4 solutions and the analytical results of acid sulfate soils also showed the similar trend.

  20. Papillomavirus microbicidal activities of high-molecular-weight cellulose sulfate, dextran sulfate, and polystyrene sulfonate.

    Science.gov (United States)

    Christensen, N D; Reed, C A; Culp, T D; Hermonat, P L; Howett, M K; Anderson, R A; Zaneveld, L J

    2001-12-01

    The high-molecular-weight sulfated or sulfonated polysaccharides or polymers cellulose sulfate, dextran sulfate, and polystyrene sulfonate were tested for microbicidal activity against bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 11 (HPV-11) and type 40 (HPV-40). In vitro assays included the BPV-1-induced focus-forming assay and transient infection of human A431 cells with HPVs. The compounds were tested for microbicidal activity directly by preincubation with virus prior to addition to cell cultures and indirectly by addition of virus to compound-treated cells and to virus-coated cells to test inactivation of the virus after virus-cell binding. The data indicated that all three compounds showed direct microbicidal activity with 50% effective concentrations between 10 to 100 microg/ml. These concentrations were nontoxic to cell cultures for both assays. When a clone of C127 cells was tested for microbicidal activity, approximately 10-fold-less compound was required to achieve a 50% reduction in BPV-1-induced foci than for the uncloned parental C127 cells. Pretreatment of cells with compound prior to addition of virus also demonstrated strong microbicidal activity with dextran sulfate and polystyrene sulfonate, but cellulose sulfate required several orders of magnitude more compound for virus inactivation. Polystyrene sulfonate prevented subsequent infection of HPV-11 after virus-cell binding, and this inactivation was observed up to 4 h after addition of virus. These data indicate that the polysulfated and polysulfonated compounds may be useful nontoxic microbicidal compounds that are active against a variety of sexually transmitted disease agents including papillomaviruses.

  1. Synergistic Extraction of Gallium for Sulfate Solution

    Institute of Scientific and Technical Information of China (English)

    DENGTong; HUANGLijuan; 等

    2002-01-01

    A novel extractant mixture, di-2-ethylhexyl phosphate (DEHPA) plus HX, was propose and tested for recovering gallium from sulfate solution.It was found that the extraction capacity of DEPHA for gallium from sulfate solution could be enhanced significantly due to the synergistic effect of acidix extractant HX. Gallium extraction is negligible below pH 0 and highly sensitive to pH of aqueous phase in the range from 0 to 1, and satisfactory extraction can be gained at pH>1. More than 96% Ga extraction was obtained using 15% DEHPA plus 2% HX. Although Fe(Ⅲ) was found to be extracted preferentially to Ga (Ⅲ), effective extraction of Ga (Ⅲ) was possible by reducing ferric to the ferrous state prior to extraction. A loaded organic phase containing 0.48g·L-1 Ga could be produced from solution of 0.12g·L-1 Ga at A/O ratio of 4:1 via three mixer-settler operation stages. Gallium was stripped quantitatively from the loaded organic phase with 1.5mol·L-1 of sulfuric acid.

  2. Molecular Structure of Aminoguanidine Sulfate Monohydrate

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-yan; ZHANG Tong-lai; QIAO Xiao-jing; YANG Li; SHAO Feng-lei

    2006-01-01

    The single crystal of aminoguanidine sulfate monohydrate [(AG)2SO4·H2O] is obtained and its structure is determined by X-ray diffraction analysis. The compound crystallizes in orthorhombic system with space group Pnma and the empirical formula C2H16N8O5S. The unit cell parameters are as follows: a=0.6759(2)nm, b=1.4131(5)nm, c=1.1650(4)nm, V=1.1128(6)n m3, Z=4, Dc=1.578g/cm3, F(000)=560, s=1.069, μ(MoKα)=0.318mm-1. The final R and Wr are 0.0312 and 0.0833, respectively. The title compound is an ionic compound and its structure unit consists of two aminoguanidium cations, one sulfate anion and one crystal water molecule, which are interconnected by electrostatic forces and hydrogen bond s into net structure, making the title compound very stable. Under a linear heat ingrate, the thermal decomposition processes of (AG)2SO4·H2O have one en dothermal dehydration stage, one melting process and one exothermic decomposition stage at 50-400℃, and can evolve abundant gas products.

  3. Diammonium tricadmium tris(sulfate dihydroxide dihydrate

    Directory of Open Access Journals (Sweden)

    Xin Yin

    2011-05-01

    Full Text Available The title compound, (NH42Cd3(SO43(OH2(H2O2, has been obtained serendipitously. It is isotypic with the heavier alkali analogues M2Cd3(SO43(OH2(H2O2 (M = K, Rb, Cs. The structure contains two Cd2+ ions, one in a general position and one with site symmetry m. The former Cd2+ ion is coordinated by three O atoms of three SO4 groups, two hydroxide O atoms and one water O atom, the latter Cd2+ ion by four O atoms of four SO4 groups and two hydroxide O atoms, both in a distorted octahedral coordination geometry. This arrangement leads to the formation of a layered framework extending parallel to (100, with the ammonium cations situated in the voids. O—H...O hydrogen bonds involving the water molecules, hydroxide groups and sulfate O atoms, as well as N—H...O hydrogen bonds between ammonium cations and sulfate O atoms consolidate the crystal packing.

  4. Synthesis and crystal structure of the coordination compound of pyridoxine with manganese sulfate

    Science.gov (United States)

    Furmanova, N. G.; Verin, I. A.; Shyityeva, N.; Sulaimankulov, K. S.; Berdalieva, Zh.; Resnyanskii, V. F.; Duishenbaeva, A. T.

    2011-11-01

    The reaction of pyridoxine with manganese sulfate in an aqueous solution gave the coordination compound MnSO4 · 2C8H11O3N · 2H2O ( I). The structure of I was determined from single-crystal X-ray diffraction data. In the centrosymmetric complex (sp. gr. Pbar 1, Z = 1), the Mn atom is coordinated by two pyridoxine molecules and two water molecules, thus adopting an octahedral coordination. The sulfate anion is also at a center of symmetry and, consequently, is disordered. The pyridoxine molecules are coordinated to the metal atom through the oxygen atoms of the deprotonated hydroxyl group and the CH2OH group that retains the hydrogen atom. The nitrogen atom is protonated in such a way that the heterocycle assumes a pyridinium character. The crystal structure also contains six water molecules of crystallization. A thermogravimetric study showed that the decomposition of I occurs in several successive steps, such as dehydration, the combustion of organic ligands, and the formation of an inorganic residue.

  5. Site-specific identification of heparan and chondroitin sulfate glycosaminoglycans in hybrid proteoglycans

    Science.gov (United States)

    Noborn, Fredrik; Gomez Toledo, Alejandro; Green, Anders; Nasir, Waqas; Sihlbom, Carina; Nilsson, Jonas; Larson, Göran

    2016-01-01

    Heparan sulfate (HS) and chondroitin sulfate (CS) are complex polysaccharides that regulate important biological pathways in virtually all metazoan organisms. The polysaccharides often display opposite effects on cell functions with HS and CS structural motifs presenting unique binding sites for specific ligands. Still, the mechanisms by which glycan biosynthesis generates complex HS and CS polysaccharides required for the regulation of mammalian physiology remain elusive. Here we present a glycoproteomic approach that identifies and differentiates between HS and CS attachment sites and provides identity to the core proteins. Glycopeptides were prepared from perlecan, a complex proteoglycan known to be substituted with both HS and CS chains, further digested with heparinase or chondroitinase ABC to reduce the HS and CS chain lengths respectively, and thereafter analyzed by nLC-MS/MS. This protocol enabled the identification of three consensus HS sites and one hybrid site, carrying either a HS or a CS chain. Inspection of the amino acid sequence at the hybrid attachment locus indicates that certain peptide motifs may encode for the chain type selection process. This analytical approach will become useful when addressing fundamental questions in basic biology specifically in elucidating the functional roles of site-specific glycosylations of proteoglycans. PMID:27694851

  6. Effects of brief and intermediate exposures to sulfate submicron aerosols and sulfate injections on cardiopulmonary function of dogs and tracheal mucous velocity of sheep

    Energy Technology Data Exchange (ETDEWEB)

    Sackner, M.A. (Mount Sinai Medical Center, Miami Beach, FL); Dougherty, R.L.; Chapman, G.A.; Cipley, J.; Perez, D.; Kwoka, M.; Reinhart, M.; Brito, M.; Schreck, R.

    1981-06-01

    Pulmonary mechanics of anesthetized dogs were not changed or were minimally altered by breathing the following compounds as submicron aerosols in concentrations up to 17.3 mg/m/sup 3/ for 7.5 min: (1) sodium chloride (as a control), (2) sodium sulfate, (3) ammonium sulfate, (4) zinc sulfate, (5) zinc ammonium sulfate, (6) ammonium bisulfate, (7) aluminum sulfate, (8) manganese sulfate, (9) nickel sulfate, (10) copper sulfate, (11) ferrous fulfate, and (12) ferric sulfate. Submicron aerosols of these compounds in concentrations of 4.1 to 8.8 mg/m/sup 3/, administered for 4 h to anesthetized dogs, did not affect mechanics of breathing, hemodynamics, and arterial blood gases. In conscious sheep, tracheal mucous velocity was not altered by exposure to the submicron aerosols of the sulfate compounds. None of these compounds, injected iv in a dose of 1 mg, had adverse effects on mechanics of breathing, pulmonary and systemic hemodynamics, or arterial blood gases. In 100-mg injections, zinc sulfate and zinc ammonium sulfate produced a fall in cardiac output, systemic hypotension, hypoxemia, and metabolic acidosis. Copper sulfate at this dose produced pulmonary hypertension, a fall in cardiac output, hypoxemia, respiratory acidosis, and a decrease of specific total respiratory conductance. It is concluded that submicron aerosols of sulfate salts do not have adverse cardiopulmonary effects when administered in high concentrations for up to 4 h. However, prolonged exposure to high concentrations of zinc sulfate, zinc ammonium sulfate, and copper sulfate aerosols might have adverse cardiopulmonary effects.

  7. Chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1) involved in chondroitin sulfate initiation: Impact of sulfation on activity and specificity.

    Science.gov (United States)

    Gulberti, Sandrine; Jacquinet, Jean-Claude; Chabel, Matthieu; Ramalanjaona, Nick; Magdalou, Jacques; Netter, Patrick; Coughtrie, Michael W H; Ouzzine, Mohamed; Fournel-Gigleux, Sylvie

    2012-04-01

    Glycosaminoglycan (GAG) assembly initiates through the formation of a linkage tetrasaccharide region serving as a primer for both chondroitin sulfate (CS) and heparan sulfate (HS) chain polymerization. A possible role for sulfation of the linkage structure and of the constitutive disaccharide unit of CS chains in the regulation of CS-GAG chain synthesis has been suggested. To investigate this, we determined whether sulfate substitution of galactose (Gal) residues of the linkage region or of N-acetylgalactosamine (GalNAc) of the disaccharide unit influences activity and specificity of chondroitin sulfate N-acetylgalactosaminyltransferase-1 (CSGalNAcT-1), a key glycosyltransferase of CS biosynthesis. We synthesized a series of sulfated and unsulfated analogs of the linkage oligosaccharide and of the constitutive unit of CS and tested these molecules as potential acceptor substrates for the recombinant human CSGalNAcT-1. We show here that sulfation at C4 or C6 of the Gal residues markedly influences CSGalNAcT-1 initiation activity and catalytic efficiency. Kinetic analysis indicates that CSGalNAcT-1 exhibited 3.6-, 1.6-, and 2.2-fold higher enzymatic efficiency due to lower K(m) values toward monosulfated trisaccharides substituted at C4 or C6 position of Gal1, and at C6 of Gal2, respectively, compared with the unsulfated oligosaccharide. This highlights the critical influence of Gal substitution on both CSGalNAcT-1 activity and specifity. No GalNAcT activity was detected toward sulfated and unsulfated analogs of the CS constitutive disaccharide (GlcA-β1,3-GalNAc), indicating that CSGalNAcT-1 was involved in initiation but not in elongation of CS chains. Our results strongly suggest that sulfation of the linkage region acts as a regulatory signal in CS chain initiation.

  8. Utilization of sulfate additives in biomass combustion: fundamental and modeling aspects

    DEFF Research Database (Denmark)

    Wu, Hao; Jespersen, Jacob Boll; Grell, Morten Nedergaard

    2013-01-01

    Sulfates, such as ammonium sulfate, aluminum sulfate and ferric sulfate, are effective additives for converting the alkali chlorides released from biomass combustion to the less harmful alkali sulfates. Optimization of the use of these additives requires knowledge on their decomposition rate and ...

  9. Characterisation of the interaction of neuropilin-1 with heparin and a heparan sulfate mimetic library of heparin-derived sugars

    Directory of Open Access Journals (Sweden)

    Katarzyna A. Uniewicz

    2014-06-01

    Full Text Available Background. Neuropilin-1 (NRP-1 is a multidomain membrane protein with soluble isoforms interacting with a complex network of other membrane receptors, their respective ligands and heparan sulfate (HS. It is involved in the development of vasculature, neural patterning, immunological responses and pathological angiogenesis.Methods. We have characterised the binding of a Fc fusion of rat NRP-1 (Fc rNRP-1 and of a soluble isoform, corresponding to the first four extracellular domains of human NRP-1, shNRP-1, using optical biosensor-based binding assays with a library of heparin derivatives. Selective labelling of lysines protected upon heparin binding allowed their identification by mass spectrometry.Results. Fc rNRP-1 bound to heparin with high affinity (2.5 nM and fast ka (9.8 × 106 M−1s−1. Unusually, NRP-1 bound both highly sulfated and completely desulfated stretches of heparin and exhibited a complex pattern of preferences for chemically modified heparins possessing one or two sulfate groups, e.g., it bound heparin with just a 6-O sulfate group better than heparin with any two of N-sulfate, 6-O sulfate and 2-O sulfate. Mass-spectrometry based mapping identified that, in addition to the expected the b1 domain, the a1, and c domains and the L2 linker were also involved in the interaction. In contrast, shNRP-1 bound heparin far more weakly. This could only be shown by affinity chromatography and by differential scanning fluorimetry.Discussion. The results suggest that the interaction of NRP-1 with HS is more complex than anticipated and involving a far greater extent of the protein than just the b1–b2 domains. NRP-1’s preference for binding long saccharide structures suggests it has the potential to bind large segments of HS chains and so organise their local structure. In contrast, the four domain soluble isoform, shNRP-1 binds heparin weakly and so would be expected to diffuse away rapidly from the source cell.

  10. Cofactor-Controlled Chirality of Tropoisomeric Ligand

    NARCIS (Netherlands)

    Théveau, L.; Bellini, R.; Dydio, P.; Szabo, Z.; van der Werf, A.; Sander, R.A.; Reek, J.N.H.; Moberg, C.

    2016-01-01

    A new tropos ligand with an integrated anion receptor receptor site has been prepared. Chiral carboxylate and phosphate anions that bind in the anion receptor unit proved capable of stabilizing chiral conformations of the achiral flexible bidentate biaryl phosphite ligand, as shown by variable

  11. Flexible Ligand Docking Using Evolutionary Algorithms

    DEFF Research Database (Denmark)

    Thomsen, Rene

    2003-01-01

    The docking of ligands to proteins can be formulated as a computational problem where the task is to find the most favorable energetic conformation among the large space of possible protein–ligand complexes. Stochastic search methods such as evolutionary algorithms (EAs) can be used to sample large...

  12. Flexible Ligand Docking Using Differential Evolution

    DEFF Research Database (Denmark)

    Thomsen, René

    2003-01-01

    the most favorable energetic conformation among the large space of possible protein-ligand complexes. Stochastic search methods, such as evolutionary algorithms (EAs), can be used to sample large search spaces effectively and is one of the preferred methods for flexible ligand docking. The differential...

  13. Rhodium olefin complexes of diiminate type ligands

    NARCIS (Netherlands)

    Willems, Sander Theodorus Hermanus

    2003-01-01

    The mono-anionic beta-diiminate ligand (ArNC(CH3)CHC(CH3)NAr) on several previous occasions proved useful in stabilising low coordination numbers for both early and late transition metals. In this thesis the reactivity of the rhodium olefin complexes of one of these beta-diiminate ligands (Ar = 2,6-

  14. Ligand sphere conversions in terminal carbide complexes

    DEFF Research Database (Denmark)

    Morsing, Thorbjørn Juul; Reinholdt, Anders; Sauer, Stephan P. A.

    2016-01-01

    Metathesis is introduced as a preparative route to terminal carbide complexes. The chloride ligands of the terminal carbide complex [RuC(Cl)2(PCy3)2] (RuC) can be exchanged, paving the way for a systematic variation of the ligand sphere. A series of substituted complexes, including the first exam...

  15. Asymmetric catalysis based on tropos ligands.

    Science.gov (United States)

    Aikawa, Kohsuke; Mikami, Koichi

    2012-11-21

    All enantiopure atropisomeric (atropos) ligands essentially require enantiomeric resolution or synthetic transformation from a chiral pool. In sharp contrast, the use of tropos (chirally flexible) ligands, which are highly modular, versatile, and easy to synthesize without enantiomeric resolution, has recently been the topic of much interest in asymmetric catalysis. Racemic catalysts bearing tropos ligands can be applied to asymmetric catalysis through enantiomeric discrimination by the addition of a chiral source, which preferentially transforms one catalyst enantiomer into a highly activated catalyst enantiomer. Additionally, racemic catalysts bearing tropos ligands can also be utilized as atropos enantiopure catalysts obtained via the control of chirality by a chiral source followed by the memory of chirality. In this feature article, our results on the asymmetric catalysis via the combination of various central metals and tropos ligands are summarized.

  16. Upper tropospheric ice sensitivity to sulfate geoengineering

    Science.gov (United States)

    Visioni, Daniele; Pitari, Giovanni; Mancini, Eva

    2017-04-01

    In light of the Paris Agreement which aims to keep global warming under 2 °C in the next century and considering the emission scenarios produced by the IPCC for the same time span, it is likely that to remain below that threshold some kind of geoengineering technique will have to be deployed. Amongst the different methods, the injection of sulfur into the stratosphere has received much attention considering its effectiveness and affordability. Aside from the rather well established surface cooling sulfate geoengineering (SG) would produce, the investigation on possible side-effects of this method is still ongoing. For instance, some recent studies have investigated the effect SG would have on upper tropospheric cirrus clouds, expecially on the homogenous freezing mechanisms that produces the ice particles (Kuebbeler et al., 2012). The goal of the present study is to better understand the effect of thermal and dynamical anomalies caused by SG on the formation of ice crystals via homogeneous freezing by comparing a complete SG simulation with a RCP4.5 reference case and with a number of sensitivity studies where atmospheric temperature changes in the upper tropospheric region are specified in a schematic way as a function of the aerosol driven stratospheric warming and mid-lower tropospheric cooling. These changes in the temperature profile tend to increase atmospheric stabilization, thus decreasing updraft and with it the amount of water vapor available for homogeneous freezing in the upper troposphere. However, what still needs to be assessed is the interaction between this dynamical effect and the thermal effects of tropospheric cooling (which would increase ice nucleation rates) and stratospheric warming (which would probably extend to the uppermost troposphere via SG aerosol gravitational settling, thus reducing ice nucleation rates), in order to understand how they combine together. Changes in ice clouds coverage could be important for SG, because cirrus ice

  17. A radioimmunoassay for measurement of thyroxine sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, I.J.; Santini, F.; Hurd, R.E.; Chua Teco, G.N. (Univ. of California Center for the Health Sciences, Los Angeles (United States))

    1993-01-01

    A highly sensitive, specific, and reproducible RIA has been developed to measure T[sub 4] sulfate (T[sub 4]S) in ethanol extracts of serum. rT[sub 3] sulfate (rT[sub 3]S) cross-reacted 7.1%, and T[sub 3]S cross-reacted 0.59% in the RIA; T[sub 4], T[sub 3], rT[sub 3] and 3,3[prime]-diiodothyronine cross-reacted 0.004% or less. The recovery of nonradioactive T[sub 4]S added to serum averaged 95%. The detection threshold of the RIA was 18 pmol/L. The coefficient of variation averaged 6.9% within an assay and 12% between assays. T[sub 4]S was bound by T[sub 4]-binding globulin and albumin in serum. The free fraction of T[sub 4]S in four normal sera averaged 0.06% compared to a value of 0.03% for T[sub 4] (P < 0.001). The serum concentration of T[sub 4]S was (mean [+-] SE) 19 [+-] 1.2 pmol/L in normal subjects, 33 [+-] 10 in hyperthyroid patients with Graves disease, 42 [+-] 15 in hypothyroid patients, 34 [+-] 6.9 in patients with systematic nonthyroidal illnesses, 21 [+-] 4.3 in pregnant women at 15-40 weeks gestation, and 245 [+-] 26 in cord blood sera of newborns; the value in the newborn was significantly different from normal (P < 0.001). Administration of sodium ipodate (Oragrafin; 3 g, orally) to hyperthyroid patients was associated with a transient increase in serum T[sub 4]S. The T[sub 4]S content of the thyroid gland was less than 1/4000th that of T[sub 4]. We conclude that (1) T[sub 4]S is a normal component of human serum, and its levels are markedly increased in newborn serum and amniotic fluid; and (2) the sulfation pathway plays an important role in the metabolism of T[sub 4] in man. 28 refs., 4 figs., 2 tabs.

  18. Ligand binding mechanics of maltose binding protein.

    Science.gov (United States)

    Bertz, Morten; Rief, Matthias

    2009-11-13

    In the past decade, single-molecule force spectroscopy has provided new insights into the key interactions stabilizing folded proteins. A few recent studies probing the effects of ligand binding on mechanical protein stability have come to quite different conclusions. While some proteins seem to be stabilized considerably by a bound ligand, others appear to be unaffected. Since force acts as a vector in space, it is conceivable that mechanical stabilization by ligand binding is dependent on the direction of force application. In this study, we vary the direction of the force to investigate the effect of ligand binding on the stability of maltose binding protein (MBP). MBP consists of two lobes connected by a hinge region that move from an open to a closed conformation when the ligand maltose binds. Previous mechanical experiments, where load was applied to the N and C termini, have demonstrated that MBP is built up of four building blocks (unfoldons) that sequentially detach from the folded structure. In this study, we design the pulling direction so that force application moves the two MBP lobes apart along the hinge axis. Mechanical unfolding in this geometry proceeds via an intermediate state whose boundaries coincide with previously reported MBP unfoldons. We find that in contrast to N-C-terminal pulling experiments, the mechanical stability of MBP is increased by ligand binding when load is applied to the two lobes and force breaks the protein-ligand interactions directly. Contour length measurements indicate that MBP is forced into an open conformation before unfolding even if ligand is bound. Using mutagenesis experiments, we demonstrate that the mechanical stabilization effect is due to only a few key interactions of the protein with its ligand. This work illustrates how varying the direction of the applied force allows revealing important details about the ligand binding mechanics of a large protein.

  19. The differences in binding 12-carbon aliphatic ligands by bovine β-lactoglobulin isoform A and B studied by isothermal titration calorimetry and X-ray crystallography.

    Science.gov (United States)

    Loch, Joanna I; Bonarek, Piotr; Polit, Agnieszka; Swiątek, Śylwia; Dziedzicka-Wasylewska, Marta; Lewiński, Krzysztof

    2013-08-01

    Isoforms A (LGB-A) and B (LGB-B) of bovine lactoglobulin, the milk protein, differ in positions 64 (D↔G) and 118 (V↔A). Interactions of LGB-A and LGB-B with sodium dodecyl sulfate (SDS), dodecyltrimethylammonium chloride (DTAC) and lauric acid (LA), 12-carbon ligands possessing differently charged polar groups, were investigated using isothermal titration calorimetry and X-ray crystallography, to study the proton linkage phenomenon and to distinguish between effects related to different isoforms and different ligand properties. The determined values of ΔS and ΔH revealed that for all ligands, binding is entropically driven. The contribution from enthalpy change is lower and shows strong dependence on type of buffer that indicates proton release from the protein varying with protein isoform and ligand type and involvement of LA and Asp64 (in isoform A) in this process. The ligand affinities for both isoforms were arranged in the same order, DTAC enthalpy, resulting in almost identical ΔG for complexes of both isoforms. The determined crystal structures showed that substitution in positions 64 and 118 did not influence the overall structure of LGB complexes. The chemical character of the ligand polar group did not affect the position of its aliphatic chain in protein β-barrel, indicating a major role of hydrophobic interactions in ligand binding that prevailed even with the repulsion between positively charged DTAC and lysine residues located at binding site entrance.

  20. Spectroscopic study of copper(II) complexes with carboxymethyl dextran and dextran sulfate

    Science.gov (United States)

    Glišić, S.; Nikolić, G.; Cakić, M.; Trutić, N.

    2015-07-01

    The copper(II) ion complexes with carboxymethyl dextran (CMD) and dextran sulfate (DS) were studied by different methods. Content of copper was determined by atomic absorption spectroscopy. It was found that copper : ligand mole ratio (Cu : CMD) is 1 : 2, and Cu : DS is 1 : 1 by mole ratio method. Spectrophotometric parameters of synthesized compounds are characteristic for Cu(II) ion in octahedral ( O h ) coordination. Analyzing of FTIR spectra in ν(C=O) vibration region has showed that -COOH group acts as bidentate ligand, while the compounds of Cu(II) with DS copper ions are in the region of four oxygen atoms of two adjacent sulfo groups. The presence of crystalline water was determined by isotopic substitution of H2O molecules with D2O molecules. Comparison of spectra recorded at room (RT) and liquid nitrogen temperature (LNT) has enabled detection bands of water molecules libration indicating that they are coordinated complementing coordination sphere of Cu(II) ions to six. The complexes are of Cu(II) · (CMD)2 · (H2O)2 or Cu(II) · DS · (H2O)2 type. The similarities of the γ(C-H) range in a part of FTIR spectra indicate that there is no difference in the conformation of the 4 C 1 glucopyranose (Glc) unit CMD and DS synthesized Cu(II) complexes.

  1. The platelet glycoprotein thrombospondin binds specifically to sulfated glycolipids.

    Science.gov (United States)

    Roberts, D D; Haverstick, D M; Dixit, V M; Frazier, W A; Santoro, S A; Ginsburg, V

    1985-08-05

    The human platelet glycoprotein thrombospondin (TSP) binds specifically and with high affinity to sulfatides (galactosylceramide-I3-sulfate). Binding of 125I-TSP to lipids from sheep and human erythrocytes and human platelets resolved on thin layer chromatograms indicates that sulfatides are the only lipids in the membrane which bind TSP. Binding to less than 2 ng of sulfatide could be detected. TSP failed to bind to other purified lipids including cholesterol 3-sulfate, phospholipids, neutral glycolipids, and gangliosides. Binding of 125I-TSP was inhibited by unlabeled TSP, by low pH, and by reduction of intersubunit disulfide bonds with dithiothreitol. A monoclonal antibody against TSP (A2.5), which inhibits hemagglutination and agglutination of fixed activated platelets by TSP, strongly inhibited TSP binding to sulfatides. A second monoclonal antibody (C6.7), which inhibits hemagglutination and aggregation of thrombin-activated live platelets, weakly inhibited sulfatide binding. Binding was inhibited by high ionic strength and by some monosaccharide sulfates including methyl-alpha-D-GlcNAc-3-sulfate. Neutral sugars did not inhibit. Fucoidan, a sulfated fucan, strongly inhibited binding with 50% inhibition at 0.3 micrograms/ml fucoidan. Other sulfated polysaccharides including heparin and dextran sulfates were good inhibitors, whereas hyaluronic acid and keratan sulfate were very weak.

  2. Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration

    Science.gov (United States)

    Belle-Oudry, Deirdre

    2008-01-01

    The determination of sulfate concentration in water by indirect EDTA titration is an instructive experiment that is easily implemented in an analytical chemistry laboratory course. A water sample is treated with excess barium chloride to precipitate sulfate ions as BaSO[subscript 4](s). The unprecipitated barium ions are then titrated with EDTA.…

  3. Transmission spectra study of sulfate substituted potassium dihydrogen phosphate

    KAUST Repository

    LI, LIANG

    2013-04-18

    Potassium dihydrogen phosphate (KDP) crystals with different amounts of sulfate concentration were grown and the transmittance spectrum was studied. A crystal with high sulfate replacement density exhibits heavy absorption property in the ultraviolet region which confirms and agrees well with former results. © 2013 Astro Ltd.

  4. Differential Expression of Specific Dermatan Sulfate Domains in Renal Pathology

    NARCIS (Netherlands)

    Lensen, J.F.M.; Vlag, J. van der; Versteeg, E.M.M.; Wetzels, J.F.M.; Heuvel, L.P.W.J. van den; Berden, J.H.M.; Kuppevelt, T.H. van; Rops, A.

    2015-01-01

    Dermatan sulfate (DS), also known as chondroitin sulfate (CS)-B, is a member of the linear polysaccharides called glycosaminoglycans (GAGs). The expression of CS/DS and DS proteoglycans is increased in several fibrotic renal diseases, including interstitial fibrosis, diabetic nephropathy, mesangial

  5. Novel Thermally Stable Poly (vinyl chloride) Composites for Sulfate Removal

    Science.gov (United States)

    BaCO3 dispersed PVC composites were prepared through a polymer re-precipitation method. The composites were tested for sulfate removal using rapid small scale column test (RSSCT) and found to significantly reduce sulfate concentration. The method was extended to synthe...

  6. Biological processes for the production of aryl sulfates

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention generally relates to the field of biotechnology as it applies to the production of aryl sulfates using polypeptides or recombinant cells comprising said polypeptides. More particularly, the present invention pertains to polypeptides having aryl sulfotransferase activity......, recombinant host cells expressing same and processes for the production of aryl sulfates employing these polypeptides or recombinant host cells....

  7. Reductive and sorptive properties of sulfate green rust (GRSO4)

    DEFF Research Database (Denmark)

    Nedel, Sorin

    The Fe(II), Fe(III) hydroxide containing sulfate in its structure, called sulfate green rust (GRSO4), can effectively reduce and convert contaminants to less mobile and less toxic forms. However, the ability of GRSO4 to remove positively charged species from solution, via sorption, is very limited...

  8. 21 CFR 520.110 - Apramycin sulfate soluble powder.

    Science.gov (United States)

    2010-04-01

    ...) caused by strains of E. coli sensitive to apramycin. (2) It is administered for 7 days in drinking water... sulfate soluble powder. (a) Specifications. A water soluble powder used to make a medicated drinking water containing apramycin sulfate equivalent to 0.375 gram of apramycin activity per gallon of drinking water....

  9. 21 CFR 173.385 - Sodium methyl sulfate.

    Science.gov (United States)

    2010-04-01

    ... Specific Usage Additives § 173.385 Sodium methyl sulfate. Sodium methyl sulfate may be present in pectin in accordance with the following conditions. (a) It is present as the result of methylation of pectin by....1 percent by weight of the pectin....

  10. Serum Indoxyl Sulfate Associates with Postangioplasty Thrombosis of Dialysis Grafts.

    Science.gov (United States)

    Wu, Chih-Cheng; Hsieh, Mu-Yang; Hung, Szu-Chun; Kuo, Ko-Lin; Tsai, Tung-Hu; Lai, Chao-Lun; Chen, Jaw-Wen; Lin, Shing-Jong; Huang, Po-Hsun; Tarng, Der-Cherng

    2016-04-01

    Hemodialysis vascular accesses are prone to recurrent stenosis and thrombosis after endovascular interventions.In vitro data suggest that indoxyl sulfate, a protein-bound uremic toxin, may induce vascular dysfunction and thrombosis. However, there is no clinical evidence regarding the role of indoxyl sulfate in hemodialysis vascular access. From January 2010 to June 2013, we prospectively enrolled patients undergoing angioplasty for dialysis access dysfunction. Patients were stratified into tertiles by baseline serum indoxyl sulfate levels. Study participants received clinical follow-up at 6-month intervals until June 2014. Primary end points were restenosis, thrombosis, and failure of vascular access. Median follow-up duration was 32 months. Of the 306 patients enrolled, 262 (86%) had symptomatic restenosis, 153 (50%) had access thrombosis, and 25 (8%) had access failure. In patients with graft access, free indoxyl sulfate tertiles showed a negative association with thrombosis-free patency (thrombosis-free patency rates of 54%, 38%, and 26% for low, middle, and high tertiles, respectively;P=0.001). Patients with graft thrombosis had higher free and total indoxyl sulfate levels. Using multivariate Cox regression analysis, graft thrombosis was independently predicted by absolute levels of free indoxyl sulfate (hazard ratio=1.14;P=0.01) and free indoxyl sulfate tertiles (high versus low, hazard ratio=2.41;P=0.001). Results of this study provide translational evidence that serum indoxyl sulfate is a novel risk factor for dialysis graft thrombosis after endovascular interventions.

  11. Sulfation of ractopamine and salbutamol by the human cytosolic sulfotransferases.

    Science.gov (United States)

    Ko, Kyounga; Kurogi, Katsuhisa; Davidson, Garrett; Liu, Ming-Yih; Sakakibara, Yoichi; Suiko, Masahito; Liu, Ming-Cheh

    2012-09-01

    Feed additives such as ractopamine and salbutamol are pharmacologically active compounds, acting primarily as β-adrenergic agonists. This study was designed to investigate whether the sulfation of ractopamine and salbutamol may occur under the metabolic conditions and to identify the human cytosolic sulfotransferases (SULTs) that are capable of sulfating two major feed additive compounds, ractopamine and salbutamol. A metabolic labelling study showed the generation and release of [(35)S]sulfated ractopamine and salbutamol by HepG2 human hepatoma cells labelled with [(35)S]sulfate in the presence of these two compounds. A systematic analysis using 11 purified human SULTs revealed SULT1A3 as the major SULT responsible for the sulfation of ractopamine and salbutamol. The pH dependence and kinetic parameters were analyzed. Moreover, the inhibitory effects of ractopamine and salbutamol on SULT1A3-mediated dopamine sulfation were investigated. Cytosol or S9 fractions of human lung, liver, kidney and small intestine were examined to verify the presence of ractopamine-/salbutamol-sulfating activity in vivo. Of the four human organs, the small intestine displayed the highest activity towards both compounds. Collectively, these results imply that the sulfation mediated by SULT1A3 may play an important role in the metabolism and detoxification of ractopamine and salbutamol.

  12. Genesis and solution chemistry of acid sulfate soils in Thailand

    NARCIS (Netherlands)

    Breemen, van N.

    1976-01-01

    To study short-term and long-term chemical processes in periodically flooded acid sulfate soils in the Bangkok Plain and in various smaller coastal plains along the Gulf of Thailand, 16 acid sulfate soils and one non-acid marine soil were examined for distribution of iron-sulfur compounds, elemental

  13. Sulfate reduction at low pH in organic wastewaters

    NARCIS (Netherlands)

    Lopes, S.I.C.

    2007-01-01

    The objective of the research described in this thesis was to investigate the operational window of dissimilatory sulfate reduction at low pH (6, 5 and 4) during the acidification of organic wastewaters. High sulfate reduction efficiencies at low pH are desirable for a more sustainable operation of

  14. Genesis and solution chemistry of acid sulfate soils in Thailand

    NARCIS (Netherlands)

    Breemen, van N.

    1976-01-01

    To study short-term and long-term chemical processes in periodically flooded acid sulfate soils in the Bangkok Plain and in various smaller coastal plains along the Gulf of Thailand, 16 acid sulfate soils and one non-acid marine soil were examined for distribution of iron-sulfur compounds, elemental

  15. Catalytic synthesis of sulfated polysaccharides I: Characterization of chemical structure.

    Science.gov (United States)

    Wang, Junlong; Yang, Wen; Yang, Ting; Zhang, Xiaonuo; Zuo, Yuan; Tian, Jia; Yao, Jian; Zhang, Ji; Lei, Ziqiang

    2015-03-01

    In the present study, sulfated derivatives of Artemisia sphaerocephala polysaccharide (SASP) with high degree of substitution (DS) were synthesized by using 4-dimethylaminopyridine (DMAP)/dimethylcyclohexylcarbodiimide (DCC) as catalyst in homogeneous conditions. It was found that DMAP/DCC showed marked improvement in DS of sulfated samples. Compared to sulfated derivatives without catalyst, the DS of SASP increased from 0.91 to 1.28 with an increment in dosage of DMAP from 0 to 10 mg. The influence of DMAP/DCC on the DS of sulfated derivatives was depended on the content of DMAP. The effect of DMAP might be due to its strong coordination to the hydroxy group. The results of FT-IR and X-ray photoelectron spectroscopy (XPS) indicated that SO3- group (S6+, binding energy of 172.3 eV) was widely present in sulfated polysaccharide molecules. 13C NMR results indicated that C-6 substitution was predominant for sulfated polysaccharide when compared with other positions. In the sulfation reaction, a sharp decrease in MW was observed. DMAP/DCC was an effective catalyst system in sulfated modification of polysaccharide.

  16. Structural characterization and bioactivities of sulfated polysaccharide from Monostroma oxyspermum.

    Science.gov (United States)

    Seedevi, Palaniappan; Moovendhan, Meivelu; Sudharsan, Sadhasivam; Vasanthkumar, Shanmugam; Srinivasan, Alagiri; Vairamani, Shanmugam; Shanmugam, Annaian

    2015-01-01

    Sulfated polysaccharide was isolated from Monostroma oxyspermum through hot water extraction, anion-exchange and gel permeation column chromatography. The sulfated polysaccharide contained 92% of carbohydrate, 0% of protein, 7.8% of uronic acid, 22% of ash and 33% of moisture respectively. The elemental composition was analyzed using CHNS/O analyzer. The molecular weight of sulfated polysaccharide determined through PAGE was found to be as 55 kDa. Monosaccharides analysis revealed that sulfated polysaccharide was composed of rhamnose, fructose, galactose, xylose, and glucose. The structural features of sulfated polysaccharide were analyzed by NMR spectroscopy. Further the sulfated polysaccharide showed total antioxidant and DPPH free radical scavenging activity were as 66.29% at 250 μg/ml and 66.83% at 160 μg/ml respectively. The sulfated polysaccharide also showed ABTS scavenging ability and reducing power were as 83.88% at 125 μg/ml and 15.81% at 400 μg/ml respectively. The anticoagulant activity was determined for human plasma with respect to Activated Partial Thromboplastin Time (APTT) and Prothrombin Time (PT) was 20.09 IU and 1.79 IU at 25 μg/ml respectively. These results indicated that the sulfated polysaccharide from M. oxyspermum had potent antioxidant and anticoagulant activities.

  17. Ovarian carcinoma cells synthesize both chondroitin sulfate and heparan sulfate cell surface proteoglycans that mediate cell adhesion to interstitial matrix.

    Science.gov (United States)

    Kokenyesi, R

    Metastatic ovarian carcinoma metastasizes by intra-peritoneal, non-hematogenous dissemination. The adhesion of the ovarian carcinoma cells to extracellular matrix components, such as types I and III collagen and cellular fibronectin, is essential for intra-peritoneal dissemination. The purpose of this study was to determine whether cell surface proteoglycans (a class of matrix receptors) are produced by ovarian carcinoma cells, and whether these proteoglycans have a role in the adhesion of ovarian carcinoma cells to types I and III collagen and fibronectin. Proteoglycans were metabolically labeled for biochemical studies. Both phosphatidylinositol-anchored and integral membrane-type cell surface proteoglycans were found to be present on the SK-OV-3 and NIH:OVCAR-3 cell lines. Three proteoglycan populations of differing hydrodynamic size were detected in both SK-OV-3 and NIH:OVCAR-3 cells. Digestions with heparitinase and chondroitinase ABC showed that cell surface proteoglycans of SK-OV-3 cells had higher proportion of chondroitin sulfate proteoglycans (75:25 of chondroitin sulfate:heparan sulfate ratio), while NIH:OVCAR-3 cells had higher proportion of heparan sulfate proteoglycans (10:90 of chondroitin sulfate:heparan sulfate ratio). RT-PCR indicated the synthesis of a unique assortment of syndecans, glypicans, and CD44 by the two cell lines. In adhesion assays performed on matrix-coated titer plates both cell lines adhered to types I and III collagen and cellular fibronectin, and cell adhesion was inhibited by preincubation of the matrix with heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, or chondroitin glycosaminoglycans. Treatment of the cells with heparitinase, chondroitinase ABC, or methylumbelliferyl xyloside also interfered with adhesion confirming the role of both heparan sulfate and chondroitin sulfate cell surface proteoglycans as matrix receptors on ovarian carcinoma cells.

  18. Effects of chlorate on the sulfation process of Trypanosoma cruzi glycoconjugates. Implication of parasite sulfates in cellular invasion.

    Science.gov (United States)

    Ferrero, Maximiliano R; Soprano, Luciana L; Acosta, Diana M; García, Gabriela A; Esteva, Mónica I; Couto, Alicia S; Duschak, Vilma G

    2014-09-01

    Sulfation, a post-translational modification which plays a key role in various biological processes, is inhibited by competition with chlorate. In Trypanosoma cruzi, the agent of Chagas' disease, sulfated structures have been described as part of glycolipids and we have reported sulfated high-mannose type oligosaccharides in the C-T domain of the cruzipain (Cz) glycoprotein. However, sulfation pathways have not been described yet in this parasite. Herein, we studied the effect of chlorate treatment on T. cruzi with the aim to gain some knowledge about sulfation metabolism and the role of sulfated molecules in this parasite. In chlorate-treated epimastigotes, immunoblotting with anti-sulfates enriched Cz IgGs (AS-enriched IgGs) showed Cz undersulfation. Accordingly, a Cz mobility shift toward higher isoelectric points was observed in 2D-PAGE probed with anti-Cz antibodies. Ultrastructural membrane abnormalities and a significant decrease of dark lipid reservosomes were shown by electron microscopy and a significant decrease in sulfatide levels was confirmed by TLC/UV-MALDI-TOF-MS analysis. Altogether, these results suggest T. cruzi sulfation occurs via PAPS. Sulfated epitopes in trypomastigote and amastigote forms were evidenced using AS-enriched IgGs by immunoblotting. Their presence on trypomastigotes surface was demonstrated by flow cytometry and IF with Cz/dCz specific antibodies. Interestingly, the percentage of infected cardiac HL-1 cells decreased 40% when using chlorate-treated trypomastigotes, suggesting sulfates are involved in the invasion process. The same effect was observed when cells were pre-incubated with dCz, dC-T or an anti-high mannose receptor (HMR) antibody, suggesting Cz sulfates and HMR are also involved in the infection process by T. cruzi.

  19. The ligand binding domain controls glucocorticoid receptor dynamics independent of ligand release.

    Science.gov (United States)

    Meijsing, Sebastiaan H; Elbi, Cem; Luecke, Hans F; Hager, Gordon L; Yamamoto, Keith R

    2007-04-01

    Ligand binding to the glucocorticoid receptor (GR) results in receptor binding to glucocorticoid response elements (GREs) and the formation of transcriptional regulatory complexes. Equally important, these complexes are continuously disassembled, with active processes driving GR off GREs. We found that co-chaperone p23-dependent disruption of GR-driven transcription depended on the ligand binding domain (LBD). Next, we examined the importance of the LBD and of ligand dissociation in GR-GRE dissociation in living cells. We showed in fluorescence recovery after photobleaching studies that dissociation of GR from GREs is faster in the absence of the LBD. Furthermore, GR interaction with a target promoter revealed ligand-specific exchange rates. However, using covalently binding ligands, we demonstrated that ligand dissociation is not required for receptor dissociation from GREs. Overall, these studies showed that activities impinging on the LBD regulate GR exchange with GREs but that the dissociation of GR from GREs is independent from ligand dissociation.

  20. Dehydroepiandrosterone, Its Sulfate and Cognitive Functions

    Science.gov (United States)

    de Menezes, Karina Junqueira; Peixoto, Clayton; Nardi, Antonio Egidio; Carta, Mauro Giovanni; Machado, Sérgio; Veras, André Barciela

    2016-01-01

    To present a review of cross-sectional and longitudinal studies that investigate the relationship between the hormones Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone sulfate (DHEA-S) and cognition. Methods: The cognition items included in this review were global cognitive function, memory, attention, executive function, intelligence, perception and visuospatial ability. A systematic review was proceeded using three databases: PubMed, ISI Web of Science, and PsycINFO. Results: Two thousand fifty five references about cognition and hormones were found; 772 duplicated references were excluded, resulting in 1.283 references to be evaluated. According to exclusion and inclusion criteria, 25 references were selected. A positive correlation between DHEA-S blood levels and global cognition was found in women and men. Other positive correlations between DHEA-S and working memory, attention and verbal fluency were found only in women. The DHEA effect on cognition is limited to one study conducted among young men with high-doses. PMID:27346998

  1. Dehydroepiandrosterone, Its Sulfate and Cognitive Functions.

    Science.gov (United States)

    de Menezes, Karina Junqueira; Peixoto, Clayton; Nardi, Antonio Egidio; Carta, Mauro Giovanni; Machado, Sérgio; Veras, André Barciela

    2016-01-01

    To present a review of cross-sectional and longitudinal studies that investigate the relationship between the hormones Dehydroepiandrosterone (DHEA) and Dehydroepiandrosterone sulfate (DHEA-S) and cognition. The cognition items included in this review were global cognitive function, memory, attention, executive function, intelligence, perception and visuospatial ability. A systematic review was proceeded using three databases: PubMed, ISI Web of Science, and PsycINFO. Two thousand fifty five references about cognition and hormones were found; 772 duplicated references were excluded, resulting in 1.283 references to be evaluated. According to exclusion and inclusion criteria, 25 references were selected. A positive correlation between DHEA-S blood levels and global cognition was found in women and men. Other positive correlations between DHEA-S and working memory, attention and verbal fluency were found only in women. The DHEA effect on cognition is limited to one study conducted among young men with high-doses.

  2. Challenges predicting ligand-receptor interactions of promiscuous proteins: the nuclear receptor PXR.

    Directory of Open Access Journals (Sweden)

    Sean Ekins

    2009-12-01

    Full Text Available Transcriptional regulation of some genes involved in xenobiotic detoxification and apoptosis is performed via the human pregnane X receptor (PXR which in turn is activated by structurally diverse agonists including steroid hormones. Activation of PXR has the potential to initiate adverse effects, altering drug pharmacokinetics or perturbing physiological processes. Reliable computational prediction of PXR agonists would be valuable for pharmaceutical and toxicological research. There has been limited success with structure-based modeling approaches to predict human PXR activators. Slightly better success has been achieved with ligand-based modeling methods including quantitative structure-activity relationship (QSAR analysis, pharmacophore modeling and machine learning. In this study, we present a comprehensive analysis focused on prediction of 115 steroids for ligand binding activity towards human PXR. Six crystal structures were used as templates for docking and ligand-based modeling approaches (two-, three-, four- and five-dimensional analyses. The best success at external prediction was achieved with 5D-QSAR. Bayesian models with FCFP_6 descriptors were validated after leaving a large percentage of the dataset out and using an external test set. Docking of ligands to the PXR structure co-crystallized with hyperforin had the best statistics for this method. Sulfated steroids (which are activators were consistently predicted as non-activators while, poorly predicted steroids were docked in a reverse mode compared to 5alpha-androstan-3beta-ol. Modeling of human PXR represents a complex challenge by virtue of the large, flexible ligand-binding cavity. This study emphasizes this aspect, illustrating modest success using the largest quantitative data set to date and multiple modeling approaches.

  3. Preparation and characterization of a chemically sulfated cashew gum polysaccharide

    Energy Technology Data Exchange (ETDEWEB)

    Moura Neto, Erico de; Maciel, Jeanny da S.; Cunha, Pablyana L. R.; Paula, Regina Celia M. de; Feitosa, Judith P.A., E-mail: judith@dqoi.ufc.br [Departamento de Quimica Organica e Inorganica, Universidade Federal do Ceara, Fortaleza (Brazil)

    2011-09-15

    Cashew gum (CG) was sulfated in pyridine:formamide using chlorosulfonic acid as the reagent. Confirmation of sulfation was obtained by Fourier transform infrared (FTIR) spectroscopy through the presence of an asymmetrical S=O stretching vibration at 1259 cm{sup -1}. The degrees of substitution were 0.02, 0.24 and 0.88 determined from the sulfur percentage. 1D and 2D nuclear magnetic resonance (NMR) data showed that the sulfation occurred at primary carbons. An increase of at least 4% of the solution viscosity was observed due to sulfation. The thermal gravimetric curves (TGA) indicate that the derivatives are stable up to ca. 200 deg C. The sulfated CG is compared to carboxymethylated CG in order to verify the possibility of the use of the former in the preparation of polyelectrolyte complexes; the latter is already being used for this application. (author)

  4. Distribution of sulfate between phases in Portland cement clinkers

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, H.F.W.

    1999-08-01

    Sulfate can occur in Portland cement clinkers as alkali sulfates, potassium calcium sulfate (calcium langbeinite), anhydrite, and as a substituent in the major phases, especially alite and belite. Data for the contents in alit and belite are reviewed and relations to bulk clinker composition are discussed. Evidence on sulfate distribution from extraction procedures is similarly considered. A procedure for predicting sulfate distribution from bulk composition is described and tested and potential sources of error in such calculations are discussed. The evidence does not support suggests that, in concrete made with present-day cements and not subjected to an elevated temperature, damage through delayed ettringite formation can occur for reasons connected with the SO{sub 3} present in the clinker.

  5. Sulfation of tea polysaccharides: synthesis, characterization and hypoglycemic activity.

    Science.gov (United States)

    Wang, Yuanfeng; Peng, Yonghua; Wei, Xinlin; Yang, Zhiwei; Xiao, Jianbo; Jin, Zhengyu

    2010-03-01

    Neutral polysaccharides (NTPS) and acid polysaccharides (ATPS) from tea leaves were obtained on a D315 macroporous anion-exchange resin column chromatography. NTPS and ATPS were sulfated by the pyridine-sulfonic acid method to obtain NTPS-S and ATPS-S. It was found that NTPS was easier sulfated than ATPS. There are strong characteristic absorption peaks located in 1258 cm(-1), 1146 cm(-1), 832 cm(-1) and 617 cm(-1) in the FTIR spectra of sulfated polysaccharides. Sulfation of polysaccharides also affected the endothermic and exothermic peaks via the DSC scan analysis. The appearance of exothermic peaks in both NTPS-S and ATPS-S indicated that the redox reaction might happen. The comparative study of hypoglycemic effect on mice showed that the sulfation of polysaccharides significantly improved hypoglycemic activity.

  6. Pressure effect on dissimilatory sulfate reduction

    Science.gov (United States)

    Williamson, A. J.; Carlson, H. K.; Coates, J. D.

    2015-12-01

    Biosouring is the production of H2S by sulfate reducing microorganisms (SRM) in-situ or in the produced fluids of oil reservoirs. Sulfide is explosive, toxic and corrosive which can trigger equipment and transportation failure, leading to environmental catastrophe. As oil exploration and reservoir development continue, subsequent enhanced recovery is occurring in progressively deeper formations and typical oil reservoir pressures range from 10-50 MPa. Therefore, an understanding of souring control effects will require an accurate understanding of the influence of pressure on SRM metabolism and the efficacy of souring control treatments at high pressure. Considerable work to date has focussed on souring control at ambient pressure; however, the influence of pressure on biogeochemical processes and souring treatments in oil reservoirs is poorly understood. To explore the impact of pressure on SRM, wild type Desulfovibrio alaskensis G20 (isolated from a producing oil well in Ventura County, California) was grown under a range of pressures (0.1-14 MPa) at 30 °C. Complete sulfate reduction occurred in all pressures tested within 3 days, but microbial growth was inhibited with increasing pressure. Bar-seq identified several genes associated with flagella biosynthesis (including FlhB) and assembly as important for survival at elevated pressure and fitness was confirmed using individual transposon mutants. Flagellar genes have previously been implicated with biofilm formation and confocal microscopy on glass slides incubated with wild type D. alaskensis G20 showed more biomass associated with surfaces under pressure, highlighting the link between pressure, flagellar and biofilm formation. To determine the effect of pressure on the efficacy of SRM inhibitors, IC50 experiments were conducted and D. alaskensis G20 showed a greater resistance to nitrate and the antibiotic chloramphenicol, but a lower resistance to perchlorate. These results will be discussed in the context of

  7. Sulfated polysaccharide, curdlan sulfate, efficiently prevents entry/fusion and restricts antibody-dependent enhancement of dengue virus infection in vitro: a possible candidate for clinical application.

    Directory of Open Access Journals (Sweden)

    Koji Ichiyama

    Full Text Available Curdlan sulfate (CRDS, a sulfated 1→3-β-D glucan, previously shown to be a potent HIV entry inhibitor, is characterized in this study as a potent inhibitor of the Dengue virus (DENV. CRDS was identified by in silico blind docking studies to exhibit binding potential to the envelope (E protein of the DENV. CRDS was shown to inhibit the DENV replication very efficiently in different cells in vitro. Minimal effective concentration of CRDS was as low as 0.1 µg/mL in LLC-MK2 cells, and toxicity was observed only at concentrations over 10 mg/mL. CRDS can also inhibit DENV-1, 3, and 4 efficiently. CRDS did not inhibit the replication of DENV subgenomic replicon. Time of addition experiments demonstrated that the compound not only inhibited viral infection at the host cell binding step, but also at an early post-attachment step of entry (membrane fusion. The direct binding of CRDS to DENV was suggested by an evident reduction in the viral titers after interaction of the virus with CRDS following an ultrafiltration device separation, as well as after virus adsorption to an alkyl CRDS-coated membrane filter. The electron microscopic features also showed that CRDS interacted directly with the viral envelope, and caused changes to the viral surface. CRDS also potently inhibited DENV infection in DC-SIGN expressing cells as well as the antibody-dependent enhancement of DENV-2 infection. Based on these data, a probable binding model of CRDS to DENV E protein was constructed by a flexible receptor and ligand docking study. The binding site of CRDS was predicted to be at the interface between domains II and III of E protein dimer, which is unique to this compound, and is apparently different from the β-OG binding site. Since CRDS has already been tested in humans without serious side effects, its clinical application can be considered.

  8. Sulfated polysaccharide, curdlan sulfate, efficiently prevents entry/fusion and restricts antibody-dependent enhancement of dengue virus infection in vitro: a possible candidate for clinical application.

    Science.gov (United States)

    Ichiyama, Koji; Gopala Reddy, Sindhoora Bhargavi; Zhang, Li Feng; Chin, Wei Xin; Muschin, Tegshi; Heinig, Lars; Suzuki, Youichi; Nanjundappa, Haraprasad; Yoshinaka, Yoshiyuki; Ryo, Akihide; Nomura, Nobuo; Ooi, Eng Eong; Vasudevan, Subhash G; Yoshida, Takashi; Yamamoto, Naoki

    2013-01-01

    Curdlan sulfate (CRDS), a sulfated 1→3-β-D glucan, previously shown to be a potent HIV entry inhibitor, is characterized in this study as a potent inhibitor of the Dengue virus (DENV). CRDS was identified by in silico blind docking studies to exhibit binding potential to the envelope (E) protein of the DENV. CRDS was shown to inhibit the DENV replication very efficiently in different cells in vitro. Minimal effective concentration of CRDS was as low as 0.1 µg/mL in LLC-MK2 cells, and toxicity was observed only at concentrations over 10 mg/mL. CRDS can also inhibit DENV-1, 3, and 4 efficiently. CRDS did not inhibit the replication of DENV subgenomic replicon. Time of addition experiments demonstrated that the compound not only inhibited viral infection at the host cell binding step, but also at an early post-attachment step of entry (membrane fusion). The direct binding of CRDS to DENV was suggested by an evident reduction in the viral titers after interaction of the virus with CRDS following an ultrafiltration device separation, as well as after virus adsorption to an alkyl CRDS-coated membrane filter. The electron microscopic features also showed that CRDS interacted directly with the viral envelope, and caused changes to the viral surface. CRDS also potently inhibited DENV infection in DC-SIGN expressing cells as well as the antibody-dependent enhancement of DENV-2 infection. Based on these data, a probable binding model of CRDS to DENV E protein was constructed by a flexible receptor and ligand docking study. The binding site of CRDS was predicted to be at the interface between domains II and III of E protein dimer, which is unique to this compound, and is apparently different from the β-OG binding site. Since CRDS has already been tested in humans without serious side effects, its clinical application can be considered.

  9. Correcting ligands, metabolites, and pathways

    Directory of Open Access Journals (Sweden)

    Vriend Gert

    2006-11-01

    Full Text Available Abstract Background A wide range of research areas in bioinformatics, molecular biology and medicinal chemistry require precise chemical structure information about molecules and reactions, e.g. drug design, ligand docking, metabolic network reconstruction, and systems biology. Most available databases, however, treat chemical structures more as illustrations than as a datafield in its own right. Lack of chemical accuracy impedes progress in the areas mentioned above. We present a database of metabolites called BioMeta that augments the existing pathway databases by explicitly assessing the validity, correctness, and completeness of chemical structure and reaction information. Description The main bulk of the data in BioMeta were obtained from the KEGG Ligand database. We developed a tool for chemical structure validation which assesses the chemical validity and stereochemical completeness of a molecule description. The validation tool was used to examine the compounds in BioMeta, showing that a relatively small number of compounds had an incorrect constitution (connectivity only, not considering stereochemistry and that a considerable number (about one third had incomplete or even incorrect stereochemistry. We made a large effort to correct the errors and to complete the structural descriptions. A total of 1468 structures were corrected and/or completed. We also established the reaction balance of the reactions in BioMeta and corrected 55% of the unbalanced (stoichiometrically incorrect reactions in an automatic procedure. The BioMeta database was implemented in PostgreSQL and provided with a web-based interface. Conclusion We demonstrate that the validation of metabolite structures and reactions is a feasible and worthwhile undertaking, and that the validation results can be used to trigger corrections and improvements to BioMeta, our metabolite database. BioMeta provides some tools for rational drug design, reaction searches, and

  10. Role of protein sulfation in vasodilation induced by minoxidil sulfate, a K+ channel opener

    Energy Technology Data Exchange (ETDEWEB)

    Meisheri, K.D.; Oleynek, J.J.; Puddington, L. (Cardiovascular Diseases Research, Upjohn Laboratories, Upjohn Company, Kalamazoo, MI (United States))

    1991-09-01

    Evidence from contractile, radioisotope ion flux and electrophysiological studies suggest that minoxidil sulfate (MNXS) acts as a K+ channel opener in vascular smooth muscle. This study was designed to examine possible biochemical mechanisms by which MNXS exerts such an effect. Experiments performed in the isolated rabbit mesenteric artery (RMA) showed that MNXS, 5 microM, but not the parent compound minoxidil, was a potent vasodilator. Whereas the relaxant effects of an another K+ channel opener vasodilator, BRL-34915 (cromakalim), were removed by washing with physiological saline solution, the effects of MNXS persisted after repeated washout attempts. Furthermore, after an initial exposure of segments of intact RMA to (35S) MNXS, greater than 30% of the radiolabel was retained 2 hr after removal of the drug. In contrast, retention of radiolabel was not detected with either (3H)MNXS (label on the piperidine ring of MNXS) or (3H)minoxidil (each less than 3% after a 2-hr washout). These data suggested that the sulfate moiety from MNXS was closely associated with the vascular tissue. To determine if proteins were the acceptors of sulfate from MNXS, intact RMAs were incubated with (35S)MNXS, and then 35S-labeled proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analyzed by fluorography. Preferential labeling of a 116 kD protein was detected by 2 and 5 min of treatment. A 43 kD protein (resembling actin) also showed significant labeling. A similar profile of 35S-labeled proteins was observed in (35S) MNXS-treated A7r5 rat aortic smooth muscle cells, suggesting that the majority of proteins labeled by (35S)MNXS in intact RMA were components of smooth muscle cells.

  11. Chondroitin / dermatan sulfate modification enzymes in zebrafish development.

    Directory of Open Access Journals (Sweden)

    Judith Habicher

    Full Text Available Chondroitin/dermatan sulfate (CS/DS proteoglycans consist of unbranched sulfated polysaccharide chains of repeating GalNAc-GlcA/IdoA disaccharide units, attached to serine residues on specific proteins. The CS/DS proteoglycans are abundant in the extracellular matrix where they have essential functions in tissue development and homeostasis. In this report a phylogenetic analysis of vertebrate genes coding for the enzymes that modify CS/DS is presented. We identify single orthologous genes in the zebrafish genome for the sulfotransferases chst7, chst11, chst13, chst14, chst15 and ust and the epimerase dse. In contrast, two copies were found for mammalian sulfotransferases CHST3 and CHST12 and the epimerase DSEL, named chst3a and chst3b, chst12a and chst12b, dsela and dselb, respectively. Expression of CS/DS modification enzymes is spatially and temporally regulated with a large variation between different genes. We found that CS/DS 4-O-sulfotransferases and 6-O-sulfotransferases as well as CS/DS epimerases show a strong and partly overlapping expression, whereas the expression is restricted for enzymes with ability to synthesize di-sulfated disaccharides. A structural analysis further showed that CS/DS sulfation increases during embryonic development mainly due to synthesis of 4-O-sulfated GalNAc while the proportion of 6-O-sulfated GalNAc increases in later developmental stages. Di-sulfated GalNAc synthesized by Chst15 and 2-O-sulfated GlcA/IdoA synthesized by Ust are rare, in accordance with the restricted expression of these enzymes. We also compared CS/DS composition with that of heparan sulfate (HS. Notably, CS/DS biosynthesis in early zebrafish development is more dynamic than HS biosynthesis. Furthermore, HS contains disaccharides with more than one sulfate group, which are virtually absent in CS/DS.

  12. Acidity-Reactivity Relationships in Catalytic Esterification over Ammonium Sulfate-Derived Sulfated Zirconia

    Directory of Open Access Journals (Sweden)

    Abdallah I. M. Rabee

    2017-07-01

    Full Text Available New insight was gained into the acidity-reactivity relationships of sulfated zirconia (SZ catalysts prepared via (NH42SO4 impregnation of Zr(OH4 for propanoic acid esterification with methanol. A family of systematically related SZs was characterized by bulk and surface analyses including XRD, XPS, TGA-MS, N2 porosimetry, temperature-programmed propylamine decomposition, and FTIR of adsorbed pyridine, as well as methylbutynol (MBOH as a reactive probe molecule. Increasing surface sulfation induces a transition from amphoteric character for the parent zirconia and low S loadings <1.7 wt %, evidenced by MBOH conversion to 3-hydroxy-3-methyl-2-butanone, methylbutyne and acetone, with higher S loadings resulting in strong Brønsted-Lewis acid pairs upon completion of the sulfate monolayer, which favored MBOH conversion to prenal. Catalytic activity for propanoic acid esterification directly correlated with acid strength determined from propylamine decomposition, coincident with the formation of Brønsted-Lewis acid pairs identified by MBOH reactive titration. Monodispersed bisulfate species are likely responsible for superacidity at intermediate sulfur loadings.

  13. Anticoagulantly active heparan sulfate and proteoheparan sulfate from cloned bovine aortic endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Marcum, J.A.; Atha, D.H.; Fritze, L.M.S.; Rosenberg, R.D.

    1986-05-01

    Heparan sulfate chains and intact proteoheparans were isolated from cloned endothelial cells of bovine aortic intima. The cells were grown in vitro and metabolically labeled using Na/sub 2/(/sup 35/S)SO/sub 4/ and/or tritiated amino acids. The radiolabeled heparan chains (M/sub r/ approx. = 30,000) and the proteoglycans were affinity fractionated on immobilized antithrombin and assayed for anticoagulant activity by radioimmunoassay for thrombin-antithrombin complex. About 1% of the heparan chains and proteoheparan bound antithrombin and accounted for >99% and >85% of the anticoagulant activity, respectively. Comparison of the bound and unbound fractions demonstrated a 6000-fold increase in specific activity for the heparan chains and a >1000-fold increase in specific activity for the proteoglycan. The disaccharide compositions of nitrous acid-cleaved heparan sulfate chains were analyzed by ion-exchange HPLC and found to have about a 4-fold enhancement in the bound fraction of GlcA ..-->.. GlcN-3-0-SO/sub 3/. This disaccharide has been shown previously to be a marker for the antithrombin binding domain in commercial heparin. These results demonstrate that bovine aortic endothelial cells synthesize heparan sulfate and proteoheparan which exhibit anticoagulant activity indistinguishable from heparin, and that the active species contains disaccharides which constitute the unique antithrombin binding domain of heparin.

  14. Low levels of H2S may replace sulfate as sulfur source in sulfate-deprived onion

    NARCIS (Netherlands)

    Durenkamp, Mark; De Kok, LJ

    2005-01-01

    Onion (Allium cepa L.) was exposed to low levels of H2S in order to investigate to what extent H2S could be used as a sulfur source for growth under sulfate-deprived conditions. Sulfate deprivation for a two-week period resulted in a decreased biomass production of the shoot, a subsequently

  15. 21 CFR 524.154 - Bacitracin or bacitracin zinc-neomycin sulfate-polymyxin B sulfate ophthalmic ointment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Bacitracin or bacitracin zinc-neomycin sulfate... TOPICAL DOSAGE FORM NEW ANIMAL DRUGS § 524.154 Bacitracin or bacitracin zinc-neomycin sulfate-polymyxin B...: (1) To 000009; each gram contains 500 units of bacitracin, 3.5 milligrams of neomycin, and...

  16. Low levels of H2S may replace sulfate as sulfur source in sulfate-deprived onion

    NARCIS (Netherlands)

    Durenkamp, Mark; De Kok, LJ

    2005-01-01

    Onion (Allium cepa L.) was exposed to low levels of H2S in order to investigate to what extent H2S could be used as a sulfur source for growth under sulfate-deprived conditions. Sulfate deprivation for a two-week period resulted in a decreased biomass production of the shoot, a subsequently decrease

  17. Impact of sulfation pattern on the conformation and dynamics of sulfated fucan oligosaccharides as revealed by NMR and MD.

    Science.gov (United States)

    Queiroz, Ismael N L; Wang, Xiaocong; Glushka, John N; Santos, Gustavo R C; Valente, Ana P; Prestegard, James H; Woods, Robert J; Mourão, Paulo A S; Pomin, Vitor H

    2015-05-01

    Sulfated fucans from sea urchin egg jelly express well-defined chemical structures that vary with species. This species specificity regulates the sperm acrosome reaction, a critical step to assure intra-specific fertilization. In addition, these polysaccharides are involved in other biological activities such as anticoagulation. Although sulfation patterns are relevant to the levels of response in both activities, conformation and dynamics of these glycans are also contributing factors. However, data about these features of sulfated fucans are very rare. To address this, we have employed nuclear magnetic resonance experiments combined with molecular dynamics on structurally defined oligosaccharides derived from two sulfated fucans. The results have indicated that the oligosaccharides are flexible in solution. Ring conformation of their composing units displays just the (1)C4 chair configuration. In a particular octasaccharide, composed of two tetrasaccharide sequences, inter-residual hydrogen bonds play a role to decrease dynamics in these repeating units. Conversely, the linking disaccharide [-3)-α-L-Fucp-2(OSO3(-))-(1-3)-α-L-Fucp-4(OCO3(-))-(1-] located right between the two tetrasaccharide units has amplified motions suggested to be promoted by electrostatic repulsion of sulfates on opposite sides of the central glycosidic bond. This conjunction of information about conformation and dynamics of sulfated fucan oligosaccharides provides new insights to explain how these glycans behave free in solution and influenced by sulfation patterns. It may also serve for future studies concerning structure-function relationship of sulfated fucans, especially those involving sea urchin fertilization and anticoagulation.

  18. Multicomponent mixtures for cryoprotection and ligand solubilization

    Directory of Open Access Journals (Sweden)

    Lidia Ciccone

    2015-09-01

    Full Text Available Mixed cryoprotectants have been developed for the solubilization of ligands for crystallization of protein–ligand complexes and for crystal soaking. Low affinity lead compounds with poor solubility are problematic for structural studies. Complete ligand solubilization is required for co-crystallization and crystal soaking experiments to obtain interpretable electron density maps for the ligand. Mixed cryo-preserving compounds are needed prior to X-ray data collection to reduce radiation damage at synchrotron sources. Here we present dual-use mixes that act as cryoprotectants and also promote the aqueous solubility of hydrophobic ligands. Unlike glycerol that increases protein solubility and can cause crystal melting the mixed solutions of cryo-preserving compounds that include precipitants and solubilizers, allow for worry-free crystal preservation while simultaneously solubilizing relatively hydrophobic ligands, typical of ligands obtained in high-throughput screening. The effectiveness of these mixture has been confirmed on a human transthyretin crystals both during crystallization and in flash freezing of crystals.

  19. Coordinate unsaturation with fluorinated ligands

    Energy Technology Data Exchange (ETDEWEB)

    Rack, J.L.; Hurlburt, P.K.; Anderson, O.P.; Strauss, S.H. [Colorado State Univ., Ft. Collins, CO (United States)

    1993-12-31

    The preparation and characterization of Zn(OTeF{sub 5}){sub 2} has resulted in a model compound with which to explore the concept of coordinative unsaturation. The coordination of solvents of varying donicity and dielectric constant to the Zn(II) ions in Zn(OTeF{sub 5}){sub 2} was studied by vapor phase monometry, NMR and IR spectroscopy, conductimetry, and X-Ray crystallography. The structures of [Zn(C{sub 6}H{sub 5}NO{sub 2}){sub 2}(OTeF{sub 5})2]2 and Zn(C{sub 6}H{sub 5}NO{sub 2}){sub 3}(OTEF{sub 5}){sub 2} demonstrate the electronic flexibility of some weakly coordinating solvents in that nitrobenzene can function as either an {eta}{sup 1}O or {eta}{sup 2}O,O`-ligand. The dependence of the number of bound solvent molecules and the degree of OTeF{sub 5}{minus} dissociation on solvent donor number and dielectric constant will be presented.

  20. Estimating Mercury-Binding Ligand Concentrations in Freshwater Wetland Porewaters Using the “Tin-Reducible-Mercury” Titration Method

    Science.gov (United States)

    Creswell, J. E.; Babiarz, C.; Shafer, M. M.; Armstrong, D. E.

    2009-12-01

    Wetland environments are recognized as active regions of mercury methylation and may represent the primary source of methylmercury to many aquatic systems. Thus understanding the methylation process in these systems is vital to efforts at prediction of methylmercury accumulation at higher trophic levels. Strong mercury-binding ligands in porewaters can limit methylation in wetlands because large ligands and charged Hg-complexes are not bioavailable to methylating bacteria. Following the method developed by Lamborg and colleagues (2003), we used tin(II) chloride, a weak reductant, to reduce and measure labile Hg in porewater samples (i.e. the fraction not bound to strong ligands). We further titrated samples with Hg(II) to determine the Hg concentration at which the naturally occurring ligands were saturated - thus providing a measure of mercury-binding ligand concentrations. To our knowledge, this is the first extensive use of this technique on porewater samples. In an effort to differentiate between inorganic- and organic-complexed Hg, we modeled the inorganic speciation of Hg using MINEQL+, an aqueous speciation modeling program. Measurements of total mercury, methylmercury, sulfide, sulfate, chloride, carbonate, pH, dissolved organic carbon, phosphate, bromide, and major ions in sample porewaters were used as inputs to the model. Using the inorganic speciation calculated by the model, and the ligand concentrations measured in our laboratory experiment, we calculated conditional stability constants for mercury-ligand binding in this system. Although modeling predicts that mercury speciation will be dominated by sulfide at the concentrations present in this system, mercury methylation rate measurements show a stronger correlation with dissolved organic carbon concentrations than with sulfide. This correlation suggests that dissolved organic carbon plays an important role in mercury speciation, even in the presence of sulfide. Porewaters were extracted from

  1. Fibronectin- and collagen-mimetic ligands regulate bone marrow stromal cell chondrogenesis in three-dimensional hydrogels

    Directory of Open Access Journals (Sweden)

    JT Connelly

    2011-09-01

    Full Text Available Modification of tissue engineering scaffolds with bioactive molecules is a potential strategy for modulating cell behavior and guiding tissue regeneration. While adhesion to RGD peptides has been shown to inhibit in vitro chondrogenesis, the effects of extracellular matrix (ECM-mimetic ligands with complex secondary and tertiary structures are unknown. This study aimed to determine whether collagen- and fibronectin-mimetic ligands would retain biologic functionality in three-dimensional (3D hydrogels, whether different ECM-mimetic ligands differentially influence in vitro chondrogenesis, and if effects of ligands on differentiation depend on soluble biochemical stimuli. A linear RGD peptide, a recombinant fibronectin fragment containing the seven to ten Type III repeats (FnIII7-10 and a triple helical, collagen mimetic peptide with the GFOGER motif were covalently coupled to agarose gels using the sulfo-SANPAH crosslinker, and bone marrow stromal cells (BMSCs were cultured within the 3D hydrogels. The ligands retained biologic functionality within the agarose gels and promoted density-dependent BMSC spreading. Interactions with all adhesive ligands inhibited stimulation by chondrogenic factors of collagen Type II and aggrecan mRNA levels and deposition of sulfated glycosaminoglycans. In medium containing fetal bovine serum, interactions with the GFOGER peptide enhanced mRNA expression of the osteogenic gene osteocalcin whereas FnIII7-10 inhibited osteocalcin expression. In conclusion, modification of agarose hydrogels with ECM-mimetic ligands can influence the differentiation of BMSCs in a manner that depends strongly on the presence and nature of soluble biochemical stimuli.

  2. Distribution of unselectively bound ligands along DNA.

    Science.gov (United States)

    Lando, Dmitri Y; Nechipurenko, Yury D

    2008-10-01

    Unselective and reversible adsorption of ligands on DNA for a model of binding proposed by Zasedatelev, Gursky, and Volkenshtein is considered. In this model, the interaction between neighboring ligands located at the distance of i binding centers is characterized by the statistical weight ai. Each ligand covers L binding centers. For this model, expressions for binding averages are represented in a new simple form. This representation is convenient for the calculation of the fraction of inter-ligand distances of i binding centers fd(i) and the fraction of binding centers included in the distances of i binding centers fbc(i) for various types of interaction between bound ligands. It is shown that, for non-cooperative binding, contact cooperativity and long-range cooperativity, the fraction of the zero inter-ligand distance fd(0) is maximal at any relative concentration of bound ligands (r). Calculations demonstrate that, at low r, fd(0) approximately r.ao, and fd(i) approximately r at 11/r-L, then fd(i) rapidly decreases with i at any r for all types of inter-ligand interaction. At high ligand concentration (r is close to rmax=L(-1)), fd(0) is close to unity and fd(i) rapidly decreases with i for any type of inter-ligand interaction. For strong contact cooperativity, fd(0) is close to unity in a much lager r interval ((0.5-1).rmax), and fd(1) approximately ao(-1) at r approximately 0.5.rmax. In the case of long-range interaction between bound ligands, the dependence fd(i) is more complex and has a maximum at i approximately (1/r-L)1/2 for anti-cooperative binding. fbc(i) is maximal at i approximately 1/r-L for all types of binding except the contact cooperativity. A strong asymmetry in the influence of contact cooperativity and anticooperativity on the ligand distribution along DNA is demonstrated.

  3. Ulvans induce resistance against plant pathogenic fungi independently of their sulfation degree.

    Science.gov (United States)

    de Freitas, Mateus B; Ferreira, Luciana G; Hawerroth, Caroline; Duarte, Maria Eugênia R; Noseda, Miguel D; Stadnik, Marciel J

    2015-11-20

    The present work aimed to evaluate the defense responses induced by chemically sulfated ulvans in Arabidopsis thaliana plants against the phytopathogenic fungi Alternaria brassicicola and Colletotrichum higginsianum. Derivatives with growing sulfate content (from 20.9 to 36.6%) were prepared with SO3-pyridine complex in formamide. NMR and FTIR spectroscopic analyses confirmed the increase of sulfate groups after the chemical sulfation process. The native sulfated polysaccharide (18.9% of sulfate) and its chemically sulfated derivatives similarly reduced the severity of both pathogenic fungi infections. Collectively, our results suggest that ulvans induce resistance against both fungal pathogens independently of its sulfation degree.

  4. Synthesis of sulfates and sulfate derivates of selected metals under harsh conditions; Synthese von Sulfaten und Sulfatderivaten ausgewaehlter Metalle unter drastischen Bedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Neuschulz, Kai

    2015-03-24

    In the course of this work sulfates und sulfate derivates of selected metals were synthesized under harsh conditions. The obtained compounds, in which the metal ions often reveal unusual oxidation states, have been characterized. Two mixed valent vanadium(IV/V) oxide sulfates (VO){sub 4}(SO{sub 4}){sub 5}, and (VO){sub 3}(SO{sub 4}){sub 4} and a vanadium(V) oxide sulfate (VO){sub 2}(SO{sub 4}){sub 3} as well as a complex anionic vanadium(V) oxide sulfate (NO)[VO(SO{sub 4}){sub 2}] have been obtained starting from vanadium or vanadium(V) oxide and oleum. All vanadium oxide sulfates reveal a similar thermal behavior. The decomposition residues are either pure vanadium(V) oxide or vanadium(IV) oxide or a mixture of both residues in different ratios. It was possible to synthesize binary tantalum(V) sulfate Ta{sub 2}(SO{sub 4}){sub 5} for the first time by reaction of pure sulfur(VI) oxide and tantalum(V) oxide at 150 C and to characterize. The complete absence of any oxide ligands at the metal center is of special interest in this compound. The reaction of tin(II) sulfate with oleum lead to the formation of tin(IV) sulfate Sn(SO{sub 4}){sub 2}. Using IR spectroscopy, the oxidation state +IV was confirmed for tin, due to the absence of OH-band in the IR-spectra, which would have meant the oxidation state +II. Using methanesulfonic acid as solvent and reactant on different synthetic routes the anhydrous methanesulfonates Mn(CH{sub 3}SO{sub 3}){sub 2}, and Fe(CH{sub 3}SO{sub 3}){sub 2}, Ga(CH{sub 3}SO{sub 3}){sub 3}, In(CH{sub 3}SO{sub 3}){sub 3}, and Tl(CH{sub 3}SO{sub 3}){sub 3}, as well as VO(CH{sub 3}SO{sub 3}){sub 2} and SnCl{sub 2}(CH{sub 3}SO{sub 3}){sub 2} were obtained. For the element thallium it was possible to obtain two mixed anionic compounds with the composition TlX{sub 2}(CH{sub 3}SO{sub 3}) (X = Cl or Br). All methanesulfonates show a similar thermal decomposition behavior forming the metal oxide as decomposition product. The thallium compounds represent

  5. Tungsten(VI) hexahydride complexes supported by chelating triphosphine ligands: Protonation to give [eta][sup 2]-dihydrogen complexes and catalytic dehydrogenation of cyclooctane to cyclooctene

    Energy Technology Data Exchange (ETDEWEB)

    Michos, D.; Xiaoliang Luo; Faller, J.W.; Crabtree, R.H. (Yale Univ., New Haven, CT (United States))

    1993-04-14

    Reactions of WCl[sub 4](PPh[sub 3])[sub 2][center dot]CH[sub 2]Cl[sub 2] with the chelating triphosphine (triphos) ligands PPh(CH[sub 2]CH[sub 2]PPh[sub 2])[sub 2] (PP[sub 2]), PPh(C[sub 6]H[sub 4]-o-PPh[sub 2])[sub 2] (TP), and MeC(CH[sub 2]PPh[sub 2])[sub 3] (P[sub 3]) in refluxing benzene or toluene give WCl[sub 4](triphos) (triphos = PP[sub 2] (1), TP (2), (3)). Treat of 1-3 with LiAlH[sub 4] in Et[sub 2]O at room temperature followed by hydrolysis in THF at 0[degrees]C affords WH[sub 6](triphos) (triphos = PP[sub 2] (4), TP (5), P[sub 3] (6)), which are the first tungsten polyhydride complexes supported by a chelating triphosphine ligand. Variable-temperature [sup 1]H NMR spectra and T[sub 1] data of 4-6 are consistent with the formulation of them as classical hexahydride complexes containing no [eta][sup 2]-H[sub 2] ligands. Reaction of 4 with Ph[sub 3]SiH in refluxing THF gives the rare silyl polyhydride complex WH[sub 5](SiPh[sub 3])(PP[sub 2]) (7). Protonation of 4-6 with HBF[sub 4][center dot]OEt[sub 2] in CD[sub 2]Cl[sub 2] at 193 K affords the cationic nonclassical [eta][sup 2]-H[sub 2] complexes [WH[sub 7[minus]2x]([eta][sup 2]-H[sub 2])[sub x](triphos)][sup +] (triphos = PP[sub 2] (8), TP (9), P[sub 3] (10); x = 1-3). Deprotonation of 8-10 with NEt[sub 3] regenerates the parent hexahydrides 4-6 quantitatively. The variable-temperature [sup 1]H NMR T[sub 1] data for the hydride resonances of 8-10 are consistent with the nonclassical [eta][sup 2]-H[sub 2] coordination. In the presence of tert-butylethylene as a hydrogen acceptor, complexes 4 and ReH[sub 5](PP[sub 2]) (11) are active catalysts for the thermal dehydrogenation of cyclooctane to cyclooctene, whereas their analogues containing monodentate phosphine ligands are inactive under similar conditions. 42 refs., 1 fig., 1 tab.

  6. The SULFs, extracellular sulfatases for heparan sulfate, promote the migration of corneal epithelial cells during wound repair.

    Directory of Open Access Journals (Sweden)

    Inna Maltseva

    Full Text Available Corneal epithelial wound repair involves the migration of epithelial cells to cover the defect followed by the proliferation of the cells to restore thickness. Heparan sulfate proteoglycans (HSPGs are ubiquitous extracellular molecules that bind to a plethora of growth factors, cytokines, and morphogens and thereby regulate their signaling functions. Ligand binding by HS chains depends on the pattern of four sulfation modifications, one of which is 6-O-sulfation of glucosamine (6OS. SULF1 and SULF2 are highly homologous, extracellular endosulfatases, which post-synthetically edit the sulfation status of HS by removing 6OS from intact chains. The SULFs thereby modulate multiple signaling pathways including the augmentation of Wnt/ß-catenin signaling. We found that wounding of mouse corneal epithelium stimulated SULF1 expression in superficial epithelial cells proximal to the wound edge. Sulf1⁻/⁻, but not Sulf2⁻/⁻, mice, exhibited a marked delay in healing. Furthermore, corneal epithelial cells derived from Sulf1⁻/⁻ mice exhibited a reduced rate of migration in repair of a scratched monolayer compared to wild-type cells. In contrast, human primary corneal epithelial cells expressed SULF2, as did a human corneal epithelial cell line (THCE. Knockdown of SULF2 in THCE cells also slowed migration, which was restored by overexpression of either mouse SULF2 or human SULF1. The interchangeability of the two SULFs establishes their capacity for functional redundancy. Knockdown of SULF2 decreased Wnt/ß-catenin signaling in THCE cells. Extracellular antagonists of Wnt signaling reduced migration of THCE cells. However in SULF2- knockdown cells, these antagonists exerted no further effects on migration, consistent with the SULF functioning as an upstream regulator of Wnt signaling. Further understanding of the mechanistic action of the SULFs in promoting corneal repair may lead to new therapeutic approaches for the treatment of corneal injuries.

  7. General Motors sulfate dispersion experiment: experimental procedures and results

    Energy Technology Data Exchange (ETDEWEB)

    Cadle, S.H.; Chock, D.P.; Monson, P.R.; Heuss, J.M.

    1977-01-01

    A massive experiment was conducted at the General Motors Proving Ground to measure the dispersion of sulfates generated by catalyst equipped vehicles. 352 cars equipped with catalysts and air pumps were driven on a 10 kilometer test track to provide a simulated freeway situation with a traffic density of 5462 cars/hour. Experiments were conducted on 17 days in October 1975, providing sixty-six 30 min data sets. On most days, the experiment was carried out early in the morning in order to run under the most adverse meteorological conditions available. Samples of airborne sulfate and a gas tracer, sulfur hexafluoride, as well as extensive meteorological data were collected simultaneously at 20 sampling points under a wide variety of meteorological conditions. The maximum measured increase in sulfate from each 30 min data set was generally found next to the roadway at the lowest level and varied from 3 to 15 ..mu..g/m/sup 3/. This increase in sulfate over background fell off rapidly with height and distance. Sulfate increases in vehicles (2 hr averages) ranged from 0 to 20 ..mu..g/m/sup 3/, and averaged 4 ..mu..g/m/sup 3/. Within experimental uncertainty, the sulfate aerosol and the gas tracer were found to disperse in the same manner. The tracer data have also been used to calculate the sulfate emission rate of the vehicles.

  8. Reconstruction of secular variation in seawater sulfate concentrations

    Science.gov (United States)

    Algeo, T. J.; Luo, G. M.; Song, H. Y.; Lyons, T. W.; Canfield, D. E.

    2015-04-01

    Long-term secular variation in seawater sulfate concentrations ([SO42-]SW) is of interest owing to its relationship to the oxygenation history of Earth's surface environment. In this study, we develop two complementary approaches for quantification of sulfate concentrations in ancient seawater and test their application to late Neoproterozoic (635 Ma) to Recent marine units. The "rate method" is based on two measurable parameters of paleomarine systems: (1) the S-isotope fractionation associated with microbial sulfate reduction (MSR), as proxied by Δ34SCAS-PY, and (2) the maximum rate of change in seawater sulfate, as proxied by &partial; δ 34SCAS/∂ t(max). The "MSR-trend method" is based on the empirical relationship of Δ34SCAS-PY to aqueous sulfate concentrations in 81 modern depositional systems. For a given paleomarine system, the rate method yields an estimate of maximum possible [SO42-]SW (although results are dependent on assumptions regarding the pyrite burial flux, FPY), and the MSR-trend method yields an estimate of mean [SO42-]SW. An analysis of seawater sulfate concentrations since 635 Ma suggests that [SO42-]SW was low during the late Neoproterozoic (short (<~2 Myr) intervals of the Cambrian, Early Triassic, Early Jurassic, and Cretaceous as a consequence of widespread ocean anoxia, intense MSR, and pyrite burial. The procedures developed in this study offer potential for future high-resolution quantitative analyses of paleo-seawater sulfate concentrations.

  9. Biological functions of iduronic acid in chondroitin/dermatan sulfate.

    Science.gov (United States)

    Thelin, Martin A; Bartolini, Barbara; Axelsson, Jakob; Gustafsson, Renata; Tykesson, Emil; Pera, Edgar; Oldberg, Åke; Maccarana, Marco; Malmstrom, Anders

    2013-05-01

    The presence of iduronic acid in chondroitin/dermatan sulfate changes the properties of the polysaccharides because it generates a more flexible chain with increased binding potentials. Iduronic acid in chondroitin/dermatan sulfate influences multiple cellular properties, such as migration, proliferation, differentiation, angiogenesis and the regulation of cytokine/growth factor activities. Under pathological conditions such as wound healing, inflammation and cancer, iduronic acid has diverse regulatory functions. Iduronic acid is formed by two epimerases (i.e. dermatan sulfate epimerase 1 and 2) that have different tissue distribution and properties. The role of iduronic acid in chondroitin/dermatan sulfate is highlighted by the vast changes in connective tissue features in patients with a new type of Ehler-Danlos syndrome: adducted thumb-clubfoot syndrome. Future research aims to understand the roles of the two epimerases and their interplay with the sulfotransferases involved in chondroitin sulfate/dermatan sulfate biosynthesis. Furthermore, a better definition of chondroitin/dermatan sulfate functions using different knockout models is needed. In this review, we focus on the two enzymes responsible for iduronic acid formation, as well as the role of iduronic acid in health and disease.

  10. Sulfate Reduction at a Lignite Seam: Microbial Abundance and Activity.

    Science.gov (United States)

    Detmers, J.; Schulte, U.; Strauss, H.; Kuever, J.

    2001-10-01

    In a combined isotope geochemical and microbiological investigation, a setting of multiple aquifers was characterized. Biologically mediated redox processes were observed in the aquifers situated in marine sands of Tertiary age and overlying Quaternary gravel deposits. Intercalated lignite seams define the aquitards, which separate the aquifers. Bacterial oxidation of organic matter is evident from dissolved inorganic carbon characterized by average carbon isotope values between ?18.4 per thousand and ?15.7 per thousand (PDB). Strongly positive sulfur isotope values of up to +50 per thousand (CTD) for residual sulfate indicate sulfate reduction under closed system conditions with respect to sulfate availability. Both, hydrochemical and isotope data are thus consistent with the recent activity of sulfate-reducing bacteria (SRB). Microbiological investigations revealed the presence of an anaerobic food chain in the aquifers. Most-probable-number (MPN) determinations for SRB and fermenting microorganisms reached highest values at the interface between aquifer and lignite seam (1.5 x 103 cells/g sediment dry mass). Five strains of SRB were isolated from highest MPN dilutions. Spore-forming bacteria appeared to dominate the SRB population. Sulfate reduction rates were determined by the 35S-radiotracer method. A detailed assessment indicates an increase in the reduction rate in proximity to the lignite seam, with a maximum turnover of 8.4 mM sulfate/a, suggesting that lignite-drived compounds represent the substrate for sulfate reduction.

  11. ALTERED ENZYMATIC ACTIVITY OF LYSOZYMES BOUND TO VARIOUSLY SULFATED CHITOSANS

    Institute of Scientific and Technical Information of China (English)

    Hong-wei Wang; Lin Yuan; Tie-liang Zhao; He Huang; Hong Chen; Di Wu

    2012-01-01

    The purpose of this research is to investigate the effects of the variously sulfated chitosans on lysozyme activity and structure.It was shown that the specific enzymatic activity of lysozyme remained almost similar to the native protein after being bound to 6-O-sulfated chitosan (6S-chitosan) and 3,6-O-sulfated chitosan (3,6S-chitosan),but decreased greatly after being bound to 2-N-6-O-sulfated chitosan (2,6S-chitosan).Meanwhile,among these sulfated chitosans,2,6S-chitosan induced the greatest conformational change in lysozyme as indicated by the fluorescence spectra.These findings demonstrated that when sulfated chitosans of different structures bind to lysozyme,lysozyme undergoes conformational change of different magnitudes,which results in corresponding levels of lysozyme activity.Further study on the interaction of sulfated chitosans with lysozyme by surface plasmon resonance (SPR) suggested that their affinities might be determined by their molecular structures.

  12. Sulfation patterns determine cellular internalization of heparin-like polysaccharides.

    Science.gov (United States)

    Raman, Karthik; Mencio, Caitlin; Desai, Umesh R; Kuberan, Balagurunathan

    2013-04-01

    Heparin is a highly sulfated polysaccharide that serves biologically relevant roles as an anticoagulant and anticancer agent. While it is well-known that modification of heparin's sulfation pattern can drastically influence its ability to bind growth factors and other extracellular molecules, very little is known about the cellular uptake of heparin and the role sulfation patterns serve in affecting its internalization. In this study, we chemically synthesized several fluorescently labeled heparins consisting of a variety of sulfation patterns. These polysaccharides were thoroughly characterized using anion exchange chromatography and size exclusion chromatography. Subsequently, we utilized flow cytometry and confocal imaging to show that sulfation patterns differentially affect the amount of heparin uptake in multiple cell types. This study provides the first comprehensive analysis of the effect of sulfation pattern on the cellular internalization of heparin or heparan sulfate like polysaccharides. The results of this study expand current knowledge regarding heparin internalization and provide insights into developing more effective heparin-based drug conjugates for applications in intracellular drug delivery.

  13. Structure versus anticoagulant and antithrombotic actions of marine sulfated polysaccharides

    Directory of Open Access Journals (Sweden)

    Vitor Hugo Pomin

    2012-08-01

    Full Text Available Marine sulfated polysaccharides (MSP, such as sulfated fucans (SF, sulfated galactans (SG and glycosaminoglycans (GAG isolated from either algae or invertebrate animals, are highly anionic polysaccharides capable of interacting with certain cationic proteins, such as (co-factors of the coagulation cascade during clotting-inhibition processes. These molecular complexes between MSP and coagulation-related proteins might, at first glance, be assumed to be driven mostly by electrostatic interactions. However, a systematic comparison using several novel sulfated polysaccharides composed of repetitive oligosaccharides with clear sulfation patterns has shown that these molecular interactions are regulated essentially by the stereochemistry of the glycans (which depends on a conjunction of anomericity, monosaccharide, conformational preference, and glycosylation and sulfation sites, rather than just a simple consequence of their negative charge density (mainly the number of sulfate groups. Here, we present an overview of the structure-function relationships of MSP, correlating their structures with their potential anticoagulant and antithrombotic actions, since pathologies related to the cardiovascular system are one of the major causes of illness and mortality in the world.

  14. Regioselective sulfation of Artemisia sphaerocephala polysaccharide: Characterization of chemical structure.

    Science.gov (United States)

    Wang, Junlong; Yang, Wen; Wang, Jiancheng; Wang, Xia; Wu, Fang; Yao, Jian; Zhang, Ji; Lei, Ziqiang

    2015-11-20

    The biological activities of sulfated polysaccharides are related to the substitution positions of functional groups. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharides (SRSASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. FT-IR spectra and X-ray photoelectron spectroscopy (XPS) showed that SO(3-) group (S(6+), high binding energy of 168.7eV) was widely present in sulfated polysaccharides. (13)C NMR spectroscopy showed that C-2 and C-3 substitution was occurred but not fully sulfation. Meanwhile, C-6 substituted signals near 65ppm were not observed. The degree of substitution varied from 0.44 to 0.63 in SRSASP which could be attributed to the low reactivity at secondary hydroxyl. Monosaccharide composition result showed a decrease in the ratio of mannose/glucose, indicating the change of chemical composition in sulfated polysaccharides. In size-exclusion chromatograph analysis, a decrease in molecular weight and broadening of molecular weight distribution of sulfated polysaccharides was also observed. It could be attributed to the hydrolysis of polysaccharide in the sulfated reaction.

  15. The influence of cloud droplet heterogeneity on sulfate production mechanisms constrained by isotopic measurements of sulfate aerosol

    Science.gov (United States)

    Alexander, B.; Allman, D. J.; Amos, H. M.; Fairlie, T. D.; Dachs, J.; Hegg, D.; Sletten, R. S.

    2011-12-01

    Observations and modeling studies have shown that heterogeneity in fog and cloud drop size and chemical composition can significantly impact in-cloud sulfate production rates due to the strong pH dependence of the ozone oxidation pathway. Averaging cloud water pH tends to underestimate the fraction of S(IV) that is SO32- leading to underestimates of in-cloud sulfate production rates. Large scale models typically do not account for this heterogeneity due to the large computational expense associated with this calculation, and instead employ bulk calculations or assumptions of cloud water pH. Modeling studies have consistently shown that calculated sulfate production rates using bulk cloud pH treatments tend to underestimate in-cloud sulfate production rates compared to more explicit treatment of cloud drop heterogeneity by underestimating the ozone oxidation pathway. Here, we utilize a global chemical transport model (GEOS-Chem) and observations of the oxygen isotopic composition of sulfate aerosol collected during a ship cruise in the subtropical northeast Atlantic Ocean to quantify sulfate formation pathways in the marine boundary layer. The oxygen isotopic composition of sulfate aerosol is particularly sensitive to the importance of the ozone oxidation pathway due to its large isotopic signature. We employ a model parameterization by Yuen et al. (1996) that accounts for the impact of alkaline, coarse-mode sea salt aerosols on in-cloud sulfate production rates. As sulfate formation in cloud droplets formed on alkaline coarse-mode sea salt aerosols is thought to be dominated by the ozone oxidation pathway, observations of the oxygen isotopic composition of sulfate aerosol provide a robust test of this parameterization. Including the Yuen et al. (1996) parameterization of cloud droplet heterogeneity improves the model's agreement with the observed sulfate oxygen isotopes. Accounting for the impact of cloud droplet heterogeneity on in-cloud sulfate production rates

  16. Evolutionary relationships and functional diversity of plant sulfate transporters

    Directory of Open Access Journals (Sweden)

    Hideki eTakahashi

    2012-01-01

    Full Text Available Sulfate is an essential nutrient cycled in nature. Ion transporters that specifically facilitate the transport of sulfate across the membranes are found ubiquitously in living organisms. The phylogenetic analysis of known sulfate transporters and their homologous proteins from eukaryotic organisms indicate two evolutionarily distinct groups of sulfate transport systems. One major group named Tribe 1 represents yeast and fungal SUL, plant SULTR and animal SLC26 families. The evolutionary origin of SULTR family members in land plants and green algae is suggested to be common with yeast and fungal sulfate transporters (SUL and animal anion exchangers (SLC26. The lineage of plant SULTR family is expanded into four subfamilies (SULTR1 to SULTR4 in land plant species. By contrast, the putative SULTR homologues from Chlorophyte green algae are in two separate lineages; one with the subfamily of plant tonoplast-localized sulfate transporters (SULTR4, and the other diverged before the appearance of lineages for SUL, SULTR and SLC26. There also was a group of yet undefined members of putative sulfate transporters in yeast and fungi divergent from these major lineages in Tribe 1. The other distinct group is Tribe 2, primarily composed of animal sodium-dependent sulfate/carboxylate transporters (SLC13 and plant tonoplast-localized dicarboxylate transporters (TDT. The putative sulfur-sensing protein (SAC1 and SAC1-like transporters (SLT of Chlorophyte green algae, bryophyte and lycophyte show low degrees of sequence similarities with SLC13 and TDT. However, the phylogenetic relationship between SAC1/SLT and the other two families, SLC13 and TDT in Tribe 2, is not clearly supported. In addition, the SAC1/SLT family is completely absent in the angiosperm species analyzed. The present study suggests distinct evolutionary trajectories of sulfate transport systems for land plants and green algae.

  17. Localized sulfate-reducing zones in a coastal plain aquifer

    Science.gov (United States)

    Brown, C.J.; Coates, J.D.; Schoonen, M.A.A.

    1999-01-01

    High concentrations of dissolved iron in ground water of coastal plain or alluvial aquifers contribute to the biofouling of public supply wells for which treatment and remediation is costly. Many of these aquifers, however, contain zones in which microbial sulfate reduction and the associated precipitation of iron-sulfide minerals decreases iron mobility. The principal water-bearing aquifer (Magothy Aquifer of Cretaceous age) in Suffolk County, New York, contains localized sulfate-reducing zones in and near lignite deposits, which generally are associated with clay lenses. Microbial analyses of core samples amended with [14C]-acetate indicate that microbial sulfate reduction is the predominant terminal-electron-accepting process (TEAP) in poorly permeable, lignite-rich sediments at shallow depths and near the ground water divide. The sulfate-reducing zones are characterized by abundant lignite and iron-sulfide minerals, low concentrations of Fe(III) oxyhydroxides, and by proximity to clay lenses that contain pore water with relatively high concentrations of sulfate and dissolved organic carbon. The low permeability of these zones and, hence, the long residence time of ground water within them, permit the preservation and (or) allow the formation of iron-sulfide minerals, including pyrite and marcasite. Both sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) are present beneath and beyond the shallow sulfate-reducing zones. A unique Fe(III)-reducing organism, MD-612, was found in core sediments from a depth of 187 m near the southern shore of Long Island. The distribution of poorly permeable, lignite-rich, sulfate-reducing zones with decreased iron concentration is varied within the principal aquifer and accounts for the observed distribution of dissolved sulfate, iron, and iron sulfides in the aquifer. Locating such zones for the placement of production wells would be difficult, however, because these zones are of limited aerial extent.

  18. Removal of Persistent Organic Contaminants by Electrochemically Activated Sulfate.

    Science.gov (United States)

    Farhat, Ali; Keller, Jurg; Tait, Stephan; Radjenovic, Jelena

    2015-12-15

    Solutions of sulfate have often been used as background electrolytes in the electrochemical degradation of contaminants and have been generally considered inert even when high-oxidation-power anodes such as boron-doped diamond (BDD) were employed. This study examines the role of sulfate by comparing electro-oxidation rates for seven persistent organic contaminants at BDD anodes in sulfate and inert nitrate anolytes. Sulfate yielded electro-oxidation rates 10-15 times higher for all target contaminants compared to the rates of nitrate anolyte. This electrochemical activation of sulfate was also observed at concentrations as low as 1.6 mM, which is relevant for many wastewaters. Electrolysis of diatrizoate in the presence of specific radical quenchers (tert-butanol and methanol) had a similar effect on electro-oxidation rates, illustrating a possible role of the hydroxyl radical ((•)OH) in the anodic formation of sulfate radical (SO4(•-)) species. The addition of 0.55 mM persulfate increased the electro-oxidation rate of diatrizoate in nitrate from 0.94 to 9.97 h(-1), suggesting a nonradical activation of persulfate. Overall findings indicate the formation of strong sulfate-derived oxidant species at BDD anodes when polarized at high potentials. This may have positive implications in the electro-oxidation of wastewaters containing sulfate. For example, the energy required for the 10-fold removal of diatrizoate was decreased from 45.6 to 2.44 kWh m(-3) by switching from nitrate to sulfate anolyte.

  19. Synthesis, Characterization, and Crystal Structure of a Novel Copper(II) Complex with an Asymmetric Coordinated 2,2'-Bipyridine Derivative: A Model for the Associative Complex in the Ligand-Substitution Reactions of [Cu(tren)L](2+)?

    Science.gov (United States)

    Lu Zl, Zhong-lin; Duan Cy, Chun-ying; Tian Yp, Yu-peng; You Xz, Xiao-zeng; Huang Xy, Xiao-ying

    1996-04-10

    The titled compound, (tris(2-aminoethyl)amine)(4,5-diazafluoren-9-one) copper(II) perchlorate, [Cu(C(6)H(18)N(4))(C(11)H(6)N(2)O)(ClO(4))(2)], 1, has been designed, synthesized, and characterized. The electronic and ESR spectra are very different from those of [Cu(tren)L](2+) complexes where L is monodentate ligand. The X-ray analysis revealed that the complex crystallizes in the monoclinic space group P2(1)/c, with a = 10.726(6) Å, b = 14.921(7) Å, c = 14.649(4) Å, beta = 95.13(3) degrees, and Z = 4. The copper(II) ion is coordinated by four nitrogen atoms from tris(2-aminoethyl)amine (tren) and two nitrogen atoms from 4,5-diazafluoren-9-one (dzf) to form an unusual six-coordinate (4 + 1 + 1') geometry. The structure is very rare, and to our knowledge, it is the first example of an asymmetric bidentate phenanthroline derivative metal complex. The structure could be used as a model of the associative complex in the ligand-exchange and ligand-substitution reactions of [Cu(tren)L](2+) and the catalytic mechanisms of enzymes involving copper sites. From the electronic and variable-temperature ESR spectra in solution, the possible mechanism of these reactions has also been proposed. As a comparison, the complex [Cu(tren)(ImH)(ClO(4))(2)], 2, was also synthesized and characterized, where ImH is imidazole.

  20. Automated design of ligands to polypharmacological profiles

    Science.gov (United States)

    Besnard, Jérémy; Ruda, Gian Filippo; Setola, Vincent; Abecassis, Keren; Rodriguiz, Ramona M.; Huang, Xi-Ping; Norval, Suzanne; Sassano, Maria F.; Shin, Antony I.; Webster, Lauren A.; Simeons, Frederick R.C.; Stojanovski, Laste; Prat, Annik; Seidah, Nabil G.; Constam, Daniel B.; Bickerton, G. Richard; Read, Kevin D.; Wetsel, William C.; Gilbert, Ian H.; Roth, Bryan L.; Hopkins, Andrew L.

    2012-01-01

    The clinical efficacy and safety of a drug is determined by its activity profile across multiple proteins in the proteome. However, designing drugs with a specific multi-target profile is both complex and difficult. Therefore methods to rationally design drugs a priori against profiles of multiple proteins would have immense value in drug discovery. We describe a new approach for the automated design of ligands against profiles of multiple drug targets. The method is demonstrated by the evolution of an approved acetylcholinesterase inhibitor drug into brain penetrable ligands with either specific polypharmacology or exquisite selectivity profiles for G-protein coupled receptors. Overall, 800 ligand-target predictions of prospectively designed ligands were tested experimentally, of which 75% were confirmed correct. We also demonstrate target engagement in vivo. The approach can be a useful source of drug leads where multi-target profiles are required to achieve either selectivity over other drug targets or a desired polypharmacology. PMID:23235874

  1. Ligand inducible assembly of a DNA tetrahedron.

    Science.gov (United States)

    Dohno, Chikara; Atsumi, Hiroshi; Nakatani, Kazuhiko

    2011-03-28

    Here we show that a small synthetic ligand can be used as a key building component for DNA nanofabrication. Using naphthyridinecarbamate dimer (NCD) as a molecular glue for DNA hybridization, we demonstrate NCD-triggered formation of a DNA tetrahedron.

  2. Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfateβ-1→3GalNAc(4-Sulfateβ-1→] motifs in dermatan sulfate on heparin cofactor II activity

    Directory of Open Access Journals (Sweden)

    Sugahara Kazuyuki

    2011-05-01

    Full Text Available Abstract Background Previously, we have reported the presence of highly sulfated dermatans in solitary ascidians from the orders Phlebobranchia (Phallusia nigra and Stolidobranchia (Halocynthia pyriformis and Styela plicata. Despite the identical disaccharide backbone, consisting of [→4IdoA(2Sβ-1→3GalNAcβ-1→], those polymers differ in the position of sulfation on the N-Acetyl galactosamine, which can occur at carbon 4 or 6. We have shown that position rather than degree of sulfation is important for heparin cofactor II activity. As a consequence, 2,4- and 2,6-sulfated dermatans have high and low heparin cofactor II activities, respectively. In the present study we extended the disaccharide analysis of ascidian dermatan sulfates to additional species of the orders Stolidobranchia (Herdmania pallida, Halocynthia roretzi and Phlebobranchia (Ciona intestinalis, aiming to investigate how sulfation evolved within Tunicata. In addition, we analysed how heparin cofactor II activity responds to dermatan sulfates containing different proportions of 2,6- or 2,4-disulfated units. Results Disaccharide analyses indicated a high content of disulfated disaccharide units in the dermatan sulfates from both orders. However, the degree of sulfation decreased from Stolidobranchia to Phlebobranchia. While 76% of the disaccharide units in dermatan sulfates from stolidobranch ascidians are disulfated, 53% of disulfated disaccharides are found in dermatan sulfates from phlebobranch ascidians. Besides this notable difference in the sulfation degree, dermatan sulfates from phlebobranch ascidians contain mainly 2,6-sulfated disaccharides whereas dermatan sulfate from the stolidobranch ascidians contain mostly 2,4-sulfated disaccharides, suggesting that the biosynthesis of dermatan sulfates might be differently regulated during tunicates evolution. Changes in the position of sulfation on N-acetylgalactosamine in the disaccharide [→4IdoA(2-Sulfateβ-1→3GalNAcβ-1

  3. Sulfated oligosaccharide structures, as determined by NMR techniques

    Energy Technology Data Exchange (ETDEWEB)

    Noseda, M.D.; Duarte, M.E.R.; Tischer, C.A.; Gorin, P.A.J. [Parana Univ., Curitiba, PR (Brazil). Dept. De Bioquimica; Cerezo, A.S. [Buenos Aires Univ. Nacional (Argentina). Dept. de Quimica Organica

    1997-12-31

    Carrageenans are sulfated polysaccharides, produced by red seaweeds (Rhodophyta), that have important biological and physico-chemical properties. Using partial autohydrolysis, we obtained sulfated oligosaccharides from a {lambda}-carrageenan (Noseda and Cerezo, 1993). These oligosaccharides are valuable not only for the study of the structures of the parent carrageenans but also for their possible biological activities. In this work we determined the chemical structure of one of the sulfated oligosaccharides using 1D and 2D NMR techniques. (author) 4 refs., 8 figs., 1 tabs.

  4. Commercial Application of Technique for Removing Sulfates from Reforming Catalyst

    Institute of Scientific and Technical Information of China (English)

    JiChangqing

    2002-01-01

    In the course of reduction of reforming catalyst by not hydrogen a certain amount of chlorine containing compounds is added to the recycle hydrogen to facilitate the reduction of sulfates.The outcome of commercial application of this technique has revealed that the procedure of "regeneration by chlorination→reduction→sulfate removal→sulfiding and oil feed-in"aimed at sulate removal is very simple and can recover the reaction activity of reforming catalyst after having been poisoned by sulfates.This procedure can be disseminated for application in refineries.

  5. Damage modelling in concrete subject to sulfate attack

    Directory of Open Access Journals (Sweden)

    N. Cefis

    2014-07-01

    Full Text Available In this paper, we consider the mechanical effect of the sulfate attack on concrete. The durability analysis of concrete structures in contact to external sulfate solutions requires the definition of a proper diffusion-reaction model, for the computation of the varying sulfate concentration and of the consequent ettringite formation, coupled to a mechanical model for the prediction of swelling and material degradation. In this work, we make use of a two-ions formulation of the reactive-diffusion problem and we propose a bi-phase chemo-elastic damage model aimed to simulate the mechanical response of concrete and apt to be used in structural analyses.

  6. Micro-SHINE Uranyl Sulfate Irradiations at the Linac

    Energy Technology Data Exchange (ETDEWEB)

    Youker, Amanda J. [Argonne National Lab. (ANL), Argonne, IL (United States); Kalensky, Michael [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Schneider, John [Argonne National Lab. (ANL), Argonne, IL (United States); Byrnes, James [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-08-01

    Peroxide formation due to water radiolysis in a uranyl sulfate solution is a concern for the SHINE Medical Technologies process in which Mo-99 is generated from the fission of dissolved low enriched uranium. To investigate the effects of power density and fission on peroxide formation and uranyl-peroxide precipitation, uranyl sulfate solutions were irradiated using a 50-MeV electron linac as part of the micro-SHINE experimental setup. Results are given for uranyl sulfate solutions with both high and low enriched uranium irradiated at different linac powers.

  7. Chemical Structures and Bioactivities of Sulfated Polysaccharides from Marine Algae

    Directory of Open Access Journals (Sweden)

    H. Stephen Ewart

    2011-02-01

    Full Text Available Sulfated polysaccharides and their lower molecular weight oligosaccharide derivatives from marine macroalgae have been shown to possess a variety of biological activities. The present paper will review the recent progress in research on the structural chemistry and the bioactivities of these marine algal biomaterials. In particular, it will provide an update on the structural chemistry of the major sulfated polysaccharides synthesized by seaweeds including the galactans (e.g., agarans and carrageenans, ulvans, and fucans. It will then review the recent findings on the anticoagulant/antithrombotic, antiviral, immuno-inflammatory, antilipidemic and antioxidant activities of sulfated polysaccharides and their potential for therapeutic application.

  8. Incorporation of Monovalent Cations in Sulfate Green Rust

    DEFF Research Database (Denmark)

    Christiansen, B. C.; Dideriksen, K.; Katz, A.;

    2014-01-01

    Green rust is a naturally occurring layered mixed-valent ferrous-ferric hydroxide, which can react with a range of redox-active compounds. Sulfate-bearing green rust is generally thought to have interlayers composed of sulfate and water. Here, we provide evidence that the interlayers also contain...... with water showed that Na+ and K+ were structurally fixed in the interlayer, whereas Rb+ and Cs+ could be removed, resulting in a decrease in the basal layer spacing. The incorporation of cations in the interlayer opens up new possibilities for the use of sulfate green rust for exchange reactions with both...

  9. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    Energy Technology Data Exchange (ETDEWEB)

    Bizzozero, Julien, E-mail: julien.bizzozero@gmail.com; Scrivener, Karen L.

    2015-10-15

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction.

  10. Initial kinetics of the direct sulfation of limestone

    DEFF Research Database (Denmark)

    Hu, Guilin; Shang, Lei; Dam-Johansen, Kim;

    2008-01-01

    The initial kinetics of direct sulfation of Faxe Bryozo, a porous bryozoan limestone was studied in the temperature interval from 873 to 973 K in a pilot entrained flow reactor with very short reaction times (between 0.1 and 0.6 s). The initial conversion rate of the limestone - for conversions...... ions in calcite grains is established. The validity of the model is limited to the initial sulfation period, in which nucleation of the solid product calcium sulphate is not started. This theoretical reaction-diffusion model gives a good simulation of the initial kinetics of the direct sulfation...

  11. Preparation and characterization of mesoporous tetragonal sulfated zirconia

    Institute of Scientific and Technical Information of China (English)

    Chun Xia He; Bin Yue; Ji Fang Cheng; Wei Ming Hua; Ying Hong Yue; He Yong He

    2009-01-01

    Mesoporous tetragonal sulfated zirconia with high surface area and narrow pore-size distribution was prepared using Zr(O-nPr)4 as zirconium precursor, sulfuric acid as sulfur source and triblock copolymer poly(ethylene glycol)-poly(propylene glycol)poly(ethylene glycol) (P123) as the template. The samples were characterized by X-ray diffraction, N2 sorption, TEM, and NH3TPD. A phase transformation from monoclinic sulfated zirconia to tetragonal sulfated zirconia is observed. The product shows strong acidity.

  12. Nye ligander for Pt-MOF strukturer

    OpenAIRE

    Jakobsen, Søren

    2006-01-01

    Metalorganic frameworks (MOFs) are a new type of compounds which have been intensely investigated during the last few years. They have been synthesized using a wide variety of metals and ligands constructing a vast number of 1, 2 and 3 dimensional structures, some of which possess zeolite-type physics and chemistry. Our approach is to incorporate platinum metal sites into the structures making them bimetallic and potentially catalytically active. Therefore a number of N-N-type ligands (dii...

  13. SnapShot: GPCR-Ligand Interactions.

    Science.gov (United States)

    Ghosh, Eshan; Nidhi, Kumari; Shukla, Arun K

    2014-12-18

    G-protein-coupled receptors enable cells to recognize numerous external stimuli and to transmit corresponding signals across the plasma membrane to trigger appropriate cellular responses. Crystal structures of a number of these receptors have now been determined in inactive and active conformations bound to chemically and functionally distinct ligands. These crystal structures illustrate overall receptor organization and atomic details of ligand-receptor interactions. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Luminescence response of an osmium(II) complex to macromolecular polyanions for the detection of heparin and chondroitin sulfate in biomedical preparations.

    Science.gov (United States)

    Wu, Hao; Wu, Jain; Saez, Christopher; Campana, Maria; Megehee, Elise G; Wang, Enju

    2013-12-04

    Heparin, dextran sulfate (DS), chondroitin sulfate (CS), and carrageenan are found to enhance the luminescence intensity of an osmium(II) carbonyl complex with phenanthroline (phen) and 4-phenylpyridine (4-phpy) ligands in aqueous and ethanol solutions. The enhancing effect of the polyanions on the luminescence of the complex is heavily dependent on the sulfate content and other factors such as structure, solubility, and counter ions of the polyanion. The highly sulfated dextran and ι-carrageenan have the most profound effect, while the low charged κ-carrageenan and CS have the least response in aqueous solution. All polyanions exhibited enhanced luminescence intensity of the complex in ethanol solutions, and even the low charged CS and κ-carrageenan enhanced the luminescence more than 4 times. DS contamination of the sodium heparin at 5% can show a significant increase in luminescence response. The osmium complex is found to be highly successful in the fast and sensitive detection of heparin in commercial injectable samples with various backgrounds as well as the detection of CS in over the counter food supplement tablets. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. A versatile dinucleating ligand containing sulfonamide groups

    DEFF Research Database (Denmark)

    Sundberg, Jonas; Witt, Hannes; Cameron, Lisa

    2014-01-01

    Copper, iron, and gallium coordination chemistries of the new pentadentate bis-sulfonamide ligand 2,6-bis(N-2-pyridylmethylsulfonamido)-4-methylphenol (psmpH3) were investigated. PsmpH3 is capable of varying degrees of deprotonation, and notably, complexes containing the fully trideprotonated...... ligand can be prepared in aqueous solutions using only divalent metal ions. Two of the copper(II) complexes, [Cu2(psmp)(OH)] and [Cu2(psmp)(OAc)2]-, demonstrate the anticipated 1:2 ligand/metal stoichiometry and show that the dimetallic binding site created for exogenous ligands possesses high inherent...... flexibility since additional one- and three-atom bridging ligands bridge the two copper(II) ions in each complex, respectively. This gives rise to a difference of 0.4 Å in the Cu···Cu distances. Complexes with 2:3 and 2:1 ligand/metal stoichiometries for the divalent and trivalent metal ions, respectively...

  16. Designer TGFβ superfamily ligands with diversified functionality.

    Directory of Open Access Journals (Sweden)

    George P Allendorph

    Full Text Available Transforming Growth Factor--beta (TGFβ superfamily ligands, including Activins, Growth and Differentiation Factors (GDFs, and Bone Morphogenetic Proteins (BMPs, are excellent targets for protein-based therapeutics because of their pervasiveness in numerous developmental and cellular processes. We developed a strategy termed RASCH (Random Assembly of Segmental Chimera and Heteromer, to engineer chemically-refoldable TGFβ superfamily ligands with unique signaling properties. One of these engineered ligands, AB208, created from Activin-βA and BMP-2 sequences, exhibits the refolding characteristics of BMP-2 while possessing Activin-like signaling attributes. Further, we find several additional ligands, AB204, AB211, and AB215, which initiate the intracellular Smad1-mediated signaling pathways more strongly than BMP-2 but show no sensitivity to the natural BMP antagonist Noggin unlike natural BMP-2. In another design, incorporation of a short N-terminal segment from BMP-2 was sufficient to enable chemical refolding of BMP-9, without which was never produced nor refolded. Our studies show that the RASCH strategy enables us to expand the functional repertoire of TGFβ superfamily ligands through development of novel chimeric TGFβ ligands with diverse biological and clinical values.

  17. LigandRFs: random forest ensemble to identify ligand-binding residues from sequence information alone

    KAUST Repository

    Chen, Peng

    2014-12-03

    Background Protein-ligand binding is important for some proteins to perform their functions. Protein-ligand binding sites are the residues of proteins that physically bind to ligands. Despite of the recent advances in computational prediction for protein-ligand binding sites, the state-of-the-art methods search for similar, known structures of the query and predict the binding sites based on the solved structures. However, such structural information is not commonly available. Results In this paper, we propose a sequence-based approach to identify protein-ligand binding residues. We propose a combination technique to reduce the effects of different sliding residue windows in the process of encoding input feature vectors. Moreover, due to the highly imbalanced samples between the ligand-binding sites and non ligand-binding sites, we construct several balanced data sets, for each of which a random forest (RF)-based classifier is trained. The ensemble of these RF classifiers forms a sequence-based protein-ligand binding site predictor. Conclusions Experimental results on CASP9 and CASP8 data sets demonstrate that our method compares favorably with the state-of-the-art protein-ligand binding site prediction methods.

  18. Fully Flexible Docking of Medium Sized Ligand Libraries with RosettaLigand.

    Directory of Open Access Journals (Sweden)

    Samuel DeLuca

    Full Text Available RosettaLigand has been successfully used to predict binding poses in protein-small molecule complexes. However, the RosettaLigand docking protocol is comparatively slow in identifying an initial starting pose for the small molecule (ligand making it unfeasible for use in virtual High Throughput Screening (vHTS. To overcome this limitation, we developed a new sampling approach for placing the ligand in the protein binding site during the initial 'low-resolution' docking step. It combines the translational and rotational adjustments to the ligand pose in a single transformation step. The new algorithm is both more accurate and more time-efficient. The docking success rate is improved by 10-15% in a benchmark set of 43 protein/ligand complexes, reducing the number of models that typically need to be generated from 1000 to 150. The average time to generate a model is reduced from 50 seconds to 10 seconds. As a result we observe an effective 30-fold speed increase, making RosettaLigand appropriate for docking medium sized ligand libraries. We demonstrate that this improved initial placement of the ligand is critical for successful prediction of an accurate binding position in the 'high-resolution' full atom refinement step.

  19. The kinetics of sulfation of calcium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, A.F.; Longwell, J.P.

    1990-01-01

    The rate of sulfation of a CaO surface is rapid at first, limited by the intrinsic kinetics, but slows down with increasing conversion as a consequence of the increased resistance to diffusion through the product layer. The objectives of this study are to determine the intrinsic kinetics and the product layer diffusion pate by minimizing the resistances to gas-phase pore diffusion, and eliminating complications due to pore filling. This is achieved by the use of nonporous CaO. A wide range of particle sizes are used to change the relative importance of the regimes in which the intrinsic kinetics and product layer diffusion control. The assumption of constant product layer diffusivity can then be tested and the variables that determine this diffusivity independently studied. Information on product layer diffusion can also be obtained from studies of porous particles after the pore mouths are all plugged and a uniform surface coating is obtained. This information on diffusion rate and intrinsic reactivity can then be combined with a geometrical model to describe the rate of reaction over the entire range of conversions and is particularly useful in treating the effect of particle size on conversion history.

  20. Monitoring sulfide and sulfate-reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, R.S.

    1995-12-31

    Simple yet precise and accurate methods for monitoring sulfate-reducing bacteria (SRB) and sulfide remain useful for the study of bacterial souring and corrosion. Test kits are available to measure sulfide in field samples. A more precise methylene blue sulfide assay for both field and laboratory studies is described here. Improved media, compared to that in API RP-38, for enumeration of SRB have been formulated. One of these, API-RST, contained cysteine (1.1 mM) as a reducing agent, which may be a confounding source of sulfide. While cysteine was required for rapid enumeration of SRB from environmental samples, the concentration of cysteine in medium could be reduced to 0.4 mM. It was also determined that elevated levels of yeast extract (>1 g/liter) could interfere with enumeration of SRB from environmental samples. The API-RST medium was modified to a RST-11 medium. Other changes in medium composition, in addition to reduction of cysteine, included reduction of the concentration of phosphate from 3.4 mM to 2.2 mM, reduction of the concentration of ferrous iron from 0.8 mM to 0.5 mM and preparation of a stock mineral solution to ease medium preparation. SRB from environmental samples could be enumerated in a week in this medium.

  1. Extraction of beryllium sulfate by a long chain amine; Extraction du sulfate de beryllium par une amine a longue chaine

    Energy Technology Data Exchange (ETDEWEB)

    Etaix, E.S. [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

    1968-06-01

    The extraction of sulfuric acid in aqueous solution by a primary amine in benzene solution, 3-9 (diethyl) - 6-amino tri-decane (D.E.T. ) - i.e., with American nomenclature 1-3 (ethyl-pentyl) - 4-ethyl-octyl amine (E.P.O.) - has made it possible to calculate the formation constants of alkyl-ammonium sulfate and acid sulfate. The formula of the beryllium and alkyl-ammonium sulfate complex formed in benzene has next been determined, for various initial acidity of the aqueous solution. Lastly, evidence has been given of negatively charged complexes of beryllium and sulfate in aqueous solution, through the dependence of the aqueous sulfate ions concentration upon beryllium extraction. The formation constant of these anionic complexes has been evaluated. (author) [French] L'etude de l'extraction de l'acide sulfurique en solution aqueuse par une amine primaire en solution dans le benzene, le diethyl-3,9 amino-6 tridecane (D.E.T.) - autre nom americain 1-3 (ethylpentyl) - 4-ethyloctylamine (E.P.O.) a permis de calculer les constantes de formation du sulfate et de l'hydrogenosulfate d'alkyl-ammonium. La formule du complexe de sulfate de beryllium et d'alkyl-ammonium forme en solution benzenique a ete ensuite determinee pour diverses acidites initiales de la solution aqueuse. Enfin, l'influence de la concentration des ions sulfate de la phase aqueuse sur l'extraction du beryllium a mis en evidence la formation en solution aqueuse de complexes anioniques de sulfate et de beryllium dont la constante de formation a ete evaluee. (auteur)

  2. Correction: Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfateβ-1→3GalNAc(4-Sulfateβ-1→] motifs in dermatan sulfate on heparin cofactor II activity

    Directory of Open Access Journals (Sweden)

    Sugahara Kazuyuki

    2011-07-01

    Full Text Available Abstract After the publication of the work entitled "Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfateβ-1→3GalNAc(4-Sulfateβ-1→] motifs in dermatan sulfate on heparin cofactor II activity", by Kozlowski et al., BMC Biochemistry 2011, 12:29, we found that the legends to Figures 2 to 5 contain serious mistakes that compromise the comprehension of the work. This correction article contains the correct text of the legends to Figures 2 to 5.

  3. Modeling the retention mechanism for high-performance liquid chromatography with a chiral ligand mobile phase and enantioseparation of mandelic acid derivatives.

    Science.gov (United States)

    Tong, Shengqiang; Shen, Mangmang; Zhang, Hu; Cheng, Dongping; Yan, Jizhong

    2015-06-01

    The chromatographic retention mechanism describing relationship between retention factor and concentration of Cu(2+) (l-phenylalanine)2 using chiral ligand mobile phase was investigated and eight mandelic acid derivatives were enantioseparated by chiral ligand exchange chromatography. The relationship between retention factor and concentration of the Cu(2+) (l-phenylalanine)2 complex was proven to be in conformity with chromatographic retention mechanism in which chiral discrimination occurred both in mobile and stationary phase. Different copper(II) salts, chiral ligands, organic modifier, pH of aqueous phase, and conventional temperature on retention behavior were optimized. Eight racemates were successfully enantioseparated on a common reversed-phase column with an optimized mobile phase composed of 6 mmol/L of l-phenylalanine or N,N-dimethyl-l-phenylalanine and 3 mmol/Lof copper(II) acetate or copper(II) sulfate aqueous solution and methanol. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    Science.gov (United States)

    Im, A.-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

    2013-10-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

  5. Synthesis and characterization of mixed ligand chiral nanoclusters

    KAUST Repository

    Guven, Zekiye P.

    2016-06-22

    Chiral mixed ligand silver nanoclusters were synthesized in the presence of a chiral and an achiral ligand. While the chiral ligand led mostly to the formation of nanoparticles, the presence of the achiral ligand drastically increased the yield of nanoclusters with enhanced chiral properties. © 2016 The Royal Society of Chemistry.

  6. ROE Wet Sulfate Deposition Raster 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2011 to 2013. Summary data in this indicator were provided by EPA’s...

  7. ROE Wet Sulfate Deposition Raster 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 1989 to 1991. Summary data in this indicator were provided by EPA’s...

  8. Specificities of Ricinus communis agglutinin 120 interaction with sulfated galactose.

    Science.gov (United States)

    Wang, Yufeng; Yu, Guangli; Han, Zhangrun; Yang, Bo; Hu, Yannan; Zhao, Xia; Wu, Jiandong; Lv, Youjing; Chai, Wengang

    2011-12-15

    Lectins are used extensively as research tools to detect and target specific oligosaccharide sequences. Ricinus communis agglutinin I (RCA(120)) recognizes non-reducing terminal β-D-galactose (Galβ) and its specificities of interactions with neutral and sialylated oligosaccharides have been well documented. Here we use carbohydrate arrays of sulfated Galβ-containing oligosaccharide probes, prepared from marine-derived galactans, to investigate their interactions with RCA(120). Our results showed that RCA(120) binding to Galβ1-4 was enhanced by 2-O- or 6-O-sulfation but abolished by 4-O-sulfation. The results were corroborated with competition experiments. Erythrina cristagalli lectin is also a Galβ-binding protein but it cannot accommodate any sulfation on Galβ.

  9. Predictive mapping of the acidifying potential for acid sulfate soils

    DEFF Research Database (Denmark)

    Boman, A; Beucher, Amélie; Mattbäck, S

    Developing methods for the predictive mapping of the potential environmental impact from acid sulfate soils is important because recent studies (e.g. Mattbäck et al., under revision) have shown that the environmental hazards (e.g. leaching of acidity) related to acid sulfate soils vary depending...... on their texture (clay, silt, sand etc.). Moreover, acidity correlates, not only with the sulfur content, but also with the electrical conductivity (EC) measured after incubation. Electromagnetic induction (EMI) data collected from an EM38 proximal sensor also enabled the detailed mapping of acid sulfate soils...... over a field (Huang et al., 2014).This study aims at assessing the use of EMI data for the predictive mapping of the acidifying potential in an acid sulfate soil area in western Finland. Different supervised classification modelling techniques, such as Artificial Neural Networks (Beucher et al., 2015...

  10. Diversity of sulfur isotope fractionations by sulfate-reducing prokaryotes

    DEFF Research Database (Denmark)

    Detmers, Jan; Brüchert, Volker; Habicht, K S

    2001-01-01

    Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known...... sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.......0 to 42.0 per thousand. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and sulfate reduction rate. The type of dissimilatory bisulfite reductase also had no effect on fractionation...

  11. Recombinant heparan sulfate for use in tissue engineering applications

    DEFF Research Database (Denmark)

    Whitelock, J.; Ma, J.L.; Davies, N.

    2008-01-01

    Background: Heparan sulfate (HS) is an important component of many extracellular matrices that interacts with mitogens and morphogens to guide and control tissue and organ development. These interactions are controlled by its structure, which varies when produced by different cell types and diffe......Background: Heparan sulfate (HS) is an important component of many extracellular matrices that interacts with mitogens and morphogens to guide and control tissue and organ development. These interactions are controlled by its structure, which varies when produced by different cell types...... in the presence of Medium 199. It was purified as a proteoglycan with a molecular weight between 75 and 150 kDa, which was decorated with HS, chondroitin sulfate (CS) and keratan sulfate (KS) in a similar way to the full-length perlecan from the same cells. Compositional analysis of the glycosaminoglycan (GAG...

  12. Heparan sulfate proteoglycans in extravasation : assisting leukocyte guidance

    NARCIS (Netherlands)

    Celie, Johanna W. A. M.; Beelen, Robert H. J.; van den Born, Jacob

    2009-01-01

    Heparan sulfate proteoglycans (HSPGs) are glycoconjugates that are implicated in various biological processes including development, inflammation and repair, which is based on their capacity to bind and present several proteins via their carbohydrate side chains (glycosaminoglycans; GAGs). Well-know

  13. Electrochemical removal of sulfate from petroleum produced water.

    Science.gov (United States)

    Jain, Pratiksha; Sharma, Mohita; Kumar, Manoj; Dureja, Prem; Singh, M P; Lal, Banwari; Sarma, Priyangshu M

    2015-01-01

    Petroleum produced water (PPW) is a waste-stream that entails huge cost on the petroleum industry. Along with other suspended and dissolved solids, it contains sulfate, which is a major hurdle for its alternative use intended toward enhanced oil recovery. This study proposes a two-step process for sulfate removal from PPW. A synthetic PPW was designed for the study using response surface methodology. During the first step, sulfate present in PPW was reduced to sulfide by anaerobic fermentation with 80% efficiency. In the second step, more than 70% of the accumulated sulfide was electrochemically oxidized. This integrated approach successfully removed sulfate from the synthetic wastewater indicating its applicability in the treatment of PPW and its subsequent applications in other oil field operations.

  14. Biotechnological aspects of sulfate reduction with methane as electron donor

    OpenAIRE

    Meulepas, R.J.W.; Stams, A.J.M.; Lens, P. N L

    2010-01-01

    Biological sulfate reduction can be used for the removal and recovery of oxidized sulfur compounds and metals from waste streams. However, the costs of conventional electron donors, like hydrogen and ethanol, limit the application possibilities. Methane from natural gas or biogas would be a more attractive electron donor. Sulfate reduction with methane as electron donor prevails in marine sediments. Recently, several authors succeeded in cultivating the responsible microorganisms in vitro. In...

  15. A New Ursane type Sulfated Saponin from Zygophyllum fabago Linn.

    Directory of Open Access Journals (Sweden)

    Saleha Suleman Khan

    2014-07-01

    Full Text Available One new sulfated saponin 3β,23,30-trihydroxyurs-20-en-28-al-23-sulfate 3-O-β- D -xylopyranoside (Zygofaboside C; 1 was purified from the water soluble fraction of ethanolic extract of the aerial parts of Zygophyllum fabago Linn. The structure of the compound was elucidated through spectral studies, especially 1D- and 2D-NMR, HR-FAB mass spectrometry, and comparison with literature data.

  16. Dextran sulfate inhibits acute Toxoplama gondii infection in pigs

    OpenAIRE

    2016-01-01

    Background Toxoplasma gondii is a highly prevalent protozoan that can infect all warm-blooded animals, including humans. Its definitive hosts are Felidae and its intermediate hosts include various other mammals and birds, including pigs. It is found in the meat of livestock which is a major source of human infection. Hence the control of toxoplasmosis in pigs is important for public health. We previously showed that dextran sulfate (DS), especially DS10 (dextran sulfate MW 10 kDa), is effecti...

  17. Calcium sulfate in periodontics: A time tested versatile alloplast

    Directory of Open Access Journals (Sweden)

    Arnav Mukherji

    2016-01-01

    Full Text Available Calcium sulfate has multifaceted properties and has versatile use in the field of periodontal practice. Calcium sulfate can function as a resorbable space filler, a resorbable barrier (compatible with guided tissue regeneration principles, as a combination with other bone grafts in intrabony defects and in socket preservation procedures for implant placement. This review is an attempt to shed light on various applications of this bone graft in periodontal regeneration.

  18. Responses to sulfated steroids of female mouse vomeronasal sensory neurons

    OpenAIRE

    Celsi, F.; d'Errico, A.; Menini, A.

    2012-01-01

    The rodent vomeronasal organ plays an important role in many social behaviors. Using the calcium imaging technique with the dye fluo-4 we measured intracellular calcium concentration changes induced by the application of sulfated steroids to neurons isolated from the vomeronasal organ of female mice. We found that a mix of 10 sulfated steroids from the androgen, estrogen, pregnanolone, and glucocorticoid families induced a calcium response in 71% of neurons. Moreover, 31% of the neurons respo...

  19. Immunohistochemical localization of chondroitin sulfate, chondroitin sulfate proteoglycan, heparan sulfate proteoglycan, entactin, and laminin in basement membranes of postnatal developing and adult rat lungs

    DEFF Research Database (Denmark)

    Sannes, P L; Burch, K K; Khosla, J

    1993-01-01

    alveolar, airway, and vascular BMs, in addition to smooth muscle external laminae (EL), in the adult and developing rat. Immunostaining for CSPG required hyaluronidase digestion, whereas CS staining was lost with the same treatment. A polyclonal antibody to the core protein of HSPG was found...... to be similarly distributed to CSPG by immunoperoxidase staining in adult and developing rat lungs, with the notable exception that little immunoreactivity for HSPG was found in smooth muscle EL. Commercially obtained polyclonal antibodies to entactin and laminin gave immunostaining comparable to that seen......Histologic preparations of lungs from 1-, 5-, 10-, 18-, and 25-day-old postnatal and adult rats were examined immunohistochemically with antibodies specific against chondroitin sulfate (CS), basement membrane chondroitin sulfate proteoglycan (BM-CSPG), heparan sulfate proteoglycan (HSPG), entactin...

  20. Persistent sulfate formation from London Fog to Chinese haze

    Science.gov (United States)

    Wang, Gehui; Zhang, Renyi; Gomez, Mario E.; Yang, Lingxiao; Levy Zamora, Misti; Hu, Min; Lin, Yun; Peng, Jianfei; Guo, Song; Meng, Jingjing; Li, Jianjun; Cheng, Chunlei; Hu, Tafeng; Ren, Yanqin; Wang, Yuesi; Gao, Jian; Cao, Junji; An, Zhisheng; Zhou, Weijian; Li, Guohui; Wang, Jiayuan; Tian, Pengfei; Marrero-Ortiz, Wilmarie; Secrest, Jeremiah; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zeng, Limin; Shao, Min; Wang, Weigang; Huang, Yao; Wang, Yuan; Zhu, Yujiao; Li, Yixin; Hu, Jiaxi; Pan, Bowen; Cai, Li; Cheng, Yuting; Ji, Yuemeng; Zhang, Fang; Rosenfeld, Daniel; Liss, Peter S.; Duce, Robert A.; Kolb, Charles E.; Molina, Mario J.

    2016-11-01

    Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.

  1. "Maternal serum Dehydroepiandrosterone Sulfate levels and successful labor induction "

    Directory of Open Access Journals (Sweden)

    Modares Gilani M

    2003-06-01

    Full Text Available To evaluate the maternal serum dehydroepiandrosterone sulfate level as a factor associated with the outcome of labor induction. Venous blood was collected from 45 women at the initiation of labor induction. Pregnancies complicated by maternal corticosteriod use, anterpartum chorioamnionitis, or cesarean delivery for indications other than arrest disorders, were excluded from analysis. In 42 women meeting inclusion criteria, induction followed established protocol. Serum dehydroepiandrosterone sulfate levels were measured by radioimmunoassay and correlated with the outcome of each induction attempt. A successful result was defined as progression to active labor. The welch approximate t-test, Mann-Whitney test, Fisher exact test, simple regression, and multiple regression were used for statistical analysis, with P<0.05 considered to be significant. The mean (±standard error dehydroepiandrosterone sulfate level was higher in women who progressed to active labor (n=25 than in those with unsuccessful attempts (n=17, (48,63±6.53 µg/dl versus 26.86±5.17 mg/dl, respectively; p= 0.03. Compared with women with dehydroepiandrosterone sulfate levels above 60 µg/dl, women with lower levels had an unsuccessful induction odds ratio (OR of 6.92 (95% confidence interval 1.74, 32.52, p= 0.01. The OR increased as dehydroepiandrosterone sulfate levels decreased. Dehydroepiandrosterone sulfate may be an important factor in successful labor induction.

  2. Sulfated phenolic acids from Dasycladales siphonous green algae.

    Science.gov (United States)

    Kurth, Caroline; Welling, Matthew; Pohnert, Georg

    2015-09-01

    Sulfated aromatic acids play a central role as mediators of chemical interactions and physiological processes in marine algae and seagrass. Among others, Dasycladus vermicularis (Scopoli) Krasser 1898 uses a sulfated hydroxylated coumarin derivative as storage metabolite for a protein cross linker that can be activated upon mechanical disruption of the alga. We introduce a comprehensive monitoring technique for sulfated metabolites based on fragmentation patterns in liquid chromatography/mass spectrometry and applied it to Dasycladales. This allowed the identification of two new aromatic sulfate esters 4-(sulfooxy)phenylacetic acid and 4-(sulfooxy)benzoic acid. The two metabolites were synthesized to prove the mass spectrometry-based structure elucidation in co-injections. We show that both metabolites are transformed to the corresponding desulfated phenols by sulfatases of bacteria. In biofouling experiments with Escherichia coli and Vibrio natriegens the desulfated forms were more active than the sulfated ones. Sulfatation might thus represent a measure of detoxification that enables the algae to store inactive forms of metabolites that are activated by settling organisms and then act as defense. Copyright © 2015. Published by Elsevier Ltd.

  3. Stratospheric sulfate geoengineering impacts on global agriculture

    Science.gov (United States)

    Xia, L.; Robock, A.; Lawrence, P.; Lombardozzi, D.

    2015-12-01

    Stratospheric sulfate geoengineering has been proposed to reduce the impacts of anthropogenic climate change. If it is ever used, it would change agricultural production, and so is one of the future climate scenarios for the third phase of the Global Gridded Crop Model Intercomparison. As an example of those impacts, we use the Community Land Model (CLM-crop 4.5) to simulate how climate changes from the G4 geoengineering scenario from the Geoengineering Modeling Intercomparison Project. The G4 geoengineering scenario specifies, in combination with RCP4.5 forcing, starting in 2020 daily injections of a constant amount of SO2 at a rate of 5 Tg SO2 per year at one point on the Equator into the lower stratosphere. Eight climate modeling groups have completed G4 simulations. We use the crop model to simulate the impacts of climate change (temperature, precipitation, and solar radiation) on the global agriculture system for five crops - rice, maize, soybeans, cotton, and sugarcane. In general, without irrigation, compared with the reference run (RCP4.5), global production of cotton, rice and sugarcane would increase significantly due to the cooling effect. Maize and soybeans show different regional responses. In tropical regions, maize and soybean have a higher yield in G4 compared with RCP4.5, while in the temperate regions they have a lower yield under a geoengineered climate. Impacts on specific countries in terms of different crop production depend on their locations. For example, the United States and Argentina show soybean production reduction of about 15% under G4 compared to RCP4.5, while Brazil increases soybean production by about 10%.

  4. Chromatofocusing of mammalian estrone sulfate sulfohydrolase activity.

    Science.gov (United States)

    Choi, H Y; Hobkirk, R

    1986-12-01

    Estrone sulfate sulfohydrolase (estrogen sulfatase) activity was solubilized by treatment with Triton X-100 from 105,000 g pellets of guinea pig uterus, testis and brain, as well as from rat liver and human placenta. The solubilized forms were subjected to chromatofocusing in the fast protein liquid chromatography (FPLC) system and on conventional columns packed in our laboratory. The guinea pig tissue pattern was complex. Uterus showed peaks of activity with apparent pI's of 9.11 and 7.6; testis contained 3 peaks with pI's of 9.18, 8.7 and 7.5; brain possessed peaks with pI's of 9.28 and 8.6. In each case the major activity peak was that with pI greater than 9. Rat liver activity chromatofocused as a single peak of apparent pI = 6.87 and the human placental enzyme also showed a single, though broad, peak, of pI = 6.57. This suggests not only that the guinea pig enzyme(s) differs markedly from those of rat liver and human placenta, but that there may be qualitative differences between the forms in the three guinea pig tissues. Chromatofocusing behaviour was not independent of the specific exchange resins and ampholytes utilized. The recovered enzyme activity was fairly stable and it seems that chromatofocusing could be a useful step in purification of the guinea pig enzyme(s), particularly the main form possessing a pI greater than 9.

  5. New polypyridine anchoring ligands for coordination complexes and surface functionalization

    OpenAIRE

    Müller, Steffen

    2015-01-01

    This PhD thesis focuses on the synthesis of new polypyridine anchoring ligands and several dfferent applications. The ligands consist of a coordinating part, a flexible linker and an anchoring group. Due to the fact that different anchoring groups were used, the ligands can be applied for several types of surface-materials. Using these anchoring ligands, several coordination complexes were synthesized. Ruthenium-based complexes, bearing an ion-sensitive ligand, were tested towards...

  6. Thermodestruction of complex sulfates of iridium and ruthenium in sulfate solutions at 100-180 deg C

    Energy Technology Data Exchange (ETDEWEB)

    Sinitsyn, N.M.; Godzhiev, S.E.; Blagodatin, Yu.V. (Moskovskij Inst. Tonkoj Khimicheskoj Tekhnologii (USSR))

    1983-12-01

    Thermodestruction of iridium- and ruthenium complex sulfates in sulfate solutions is studied at 100-180 deg C depending on the solution acidity, hold time, element initial chemical form in the solution, salt background. The complex ruthenium sulfates are shown to be destroyed during high-temperature solution holding with the solid phase formation, the rate of platinum metal transfer into a precipitate increasing with the temperature, hold time and pH of the source solution. Depending on the initial chemical form the thermodestruction proceeds in various ways and leads to the formation of either hydroxides or solid phase ''proper'' of the platinium metal salt. A reduced tendency to high-temperature hydrolysis of complex ruthenium sulfates at the +3 oxidation level is noted.

  7. Multiple ligand simultaneous docking: orchestrated dancing of ligands in binding sites of protein.

    Science.gov (United States)

    Li, Huameng; Li, Chenglong

    2010-07-30

    Present docking methodologies simulate only one single ligand at a time during docking process. In reality, the molecular recognition process always involves multiple molecular species. Typical protein-ligand interactions are, for example, substrate and cofactor in catalytic cycle; metal ion coordination together with ligand(s); and ligand binding with water molecules. To simulate the real molecular binding processes, we propose a novel multiple ligand simultaneous docking (MLSD) strategy, which can deal with all the above processes, vastly improving docking sampling and binding free energy scoring. The work also compares two search strategies: Lamarckian genetic algorithm and particle swarm optimization, which have respective advantages depending on the specific systems. The methodology proves robust through systematic testing against several diverse model systems: E. coli purine nucleoside phosphorylase (PNP) complex with two substrates, SHP2NSH2 complex with two peptides and Bcl-xL complex with ABT-737 fragments. In all cases, the final correct docking poses and relative binding free energies were obtained. In PNP case, the simulations also capture the binding intermediates and reveal the binding dynamics during the recognition processes, which are consistent with the proposed enzymatic mechanism. In the other two cases, conventional single-ligand docking fails due to energetic and dynamic coupling among ligands, whereas MLSD results in the correct binding modes. These three cases also represent potential applications in the areas of exploring enzymatic mechanism, interpreting noisy X-ray crystallographic maps, and aiding fragment-based drug design, respectively.

  8. Immobilisation of ligands by radio-derivatized polymers; Immobilisering av ligander med radioderiverte polymerer

    Energy Technology Data Exchange (ETDEWEB)

    Varga, J.M.; Fritsch, P.

    1995-01-30

    The invention relates to radio-derivatized polymers and a method of producing them by contacting non-polymerizable conjugands with radiolysable polymers in the presence of irradiation. The resulting radio-derivatized polymers can be further linked with ligand of organic or inorganic nature to immobilize such ligands. 2 figs., 5 tabs.

  9. Highly sulfated hexasaccharide sequences isolated from chondroitin sulfate of shark fin cartilage: insights into the sugar sequences with bioactivities.

    Science.gov (United States)

    Mizumoto, Shuji; Murakoshi, Saori; Kalayanamitra, Kittiwan; Deepa, Sarama Sathyaseelan; Fukui, Shigeyuki; Kongtawelert, Prachya; Yamada, Shuhei; Sugahara, Kazuyuki

    2013-02-01

    Chondroitin sulfate (CS) chains regulate the development of the central nervous system in vertebrates and are linear polysaccharides consisting of variously sulfated repeating disaccharides, [-4GlcUAβ1-3GalNAcβ1-](n), where GlcUA and GalNAc represent D-glucuronic acid and N-acetyl-D-galactosamine, respectively. CS chains containing D-disaccharide units [GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate)] are involved in the development of cerebellar Purkinje cells and neurite outgrowth-promoting activity through interaction with a neurotrophic factor, pleiotrophin, resulting in the regulation of signaling. In this study, to obtain further structural information on the CS chains containing d-disaccharide units involved in brain development, oligosaccharides containing D-units were isolated from a shark fin cartilage. Seven novel hexasaccharide sequences, ΔO-D-D, ΔA-D-D, ΔC-D-D, ΔE-A-D, ΔD-D-C, ΔE-D-D and ΔA-B-D, in addition to three previously reported sequences, ΔC-A-D, ΔC-D-C and ΔA-D-A, were isolated from a CS preparation of shark fin cartilage after exhaustive digestion with chondroitinase AC-I, which cannot act on the galactosaminidic linkages bound to D-units. The symbol Δ stands for a 4,5-unsaturated bond of uronic acids, whereas A, B, C, D, E and O represent [GlcUA-GalNAc(4-O-sulfate)], [GlcUA(2-O-sulfate)-GalNAc(4-O-sulfate)], [GlcUA-GalNAc(6-O-sulfate)], [GlcUA(2-O-sulfate)-GalNAc(6-O-sulfate)], [GlcUA-GalNAc(4-O-, 6-O-sulfate)] and [GlcUA-GalNAc], respectively. In binding studies using an anti-CS monoclonal antibody, MO-225, the epitopes of which are involved in cerebellar development in mammals, novel epitope structures, ΔA-D-A, ΔA-D-D and ΔA-B-D, were revealed. Hexasaccharides containing two consecutive D-units or a B-unit will be useful for the structural and functional analyses of CS chains particularly in the neuroglycobiological fields.

  10. Organotellurium ligands - designing and complexation reactions

    Indian Academy of Sciences (India)

    Ajai K Singh

    2002-08-01

    A variety of tellurium ligands has been designed and studied for their complexation reactions in the last decade. Of these hybrid telluroethers, halotellurium ligands and polytellurides are the most notable ones. RTe- and polytelluride ions have also been used to design clusters. Ligation of ditelluroethers and several hybrid telluroethers is extensively studied in our laboratories. The ditelluroether ligand RTeCH2TeR (where R = 4-MeOC6H4) (1), similar to dppm [1,2-bis(diphenylphosphino) methane], has been synthesized in good yield (∼80 %) by reacting CHCl3 with RTe- (generated in situ by borohydride reduction of R2Te2). Iodine reacts with 1 to give tetra-iodo derivative, which has intermolecular Te$\\cdots$I interactions resulting in a macro structure containing rectangular Te-I$\\cdots$Te bridges. 1 readily forms four membered rings with Pd(II) and Ru(II). On the formation of this chelate ring, the signal in 125Te NMR spectra shifts significantly upfield (50-60 ppm). The bridging mode of 1 has been shown in [Ru(-cymene)Cl2](-1)[Ru(-cymene)Cl2]. The hybrid telluroether ligands explored are of the types (Te, S), (Te, N) and (Te, O). The tellurium donor site has strong trans influence, which is manifested more strongly in square planar complexes of palladium(II). The morpholine N-donor site has been found to have weaker donor characteristics in (Te, N) ligands than pyridine and alkylamine donor sites of analogous ligands. The singlet oxygen readily oxidises the coordinated Te. This oxidation follows first order kinetics. The complexation reaction of RuCl3.H2O with N-[2-(4-methoxyphenyltelluro)ethyl]phthalimide (2) results in a novel (Te, N, O)-heterocycle, Te-chloro,Te-anisyl-1a-aza-4-oxa-3-tellura-1H, 2H, 4aH-9 fluorenone. The (Te, O) ligands can be used as hemilabile ligands, the oxygen atom temporarily protects the vacant coordination site before the arrival of the substrate. The chelate shifts observed in 125Te NMR spectra of metal complexes of Te-ligands have

  11. Requirement of keratan sulfate proteoglycan phosphacan with a specific sulfation pattern for critical period plasticity in the visual cortex.

    Science.gov (United States)

    Takeda-Uchimura, Yoshiko; Uchimura, Kenji; Sugimura, Taketoshi; Yanagawa, Yuchio; Kawasaki, Toshisuke; Komatsu, Yukio; Kadomatsu, Kenji

    2015-12-01

    Proteoglycans play important roles in regulating the development and functions of the brain. They consist of a core protein and glycosaminoglycans, which are long sugar chains of repeating disaccharide units with sulfation. A recent study demonstrated that the sulfation pattern of chondroitin sulfate on proteoglycans contributes to regulation of the critical period of experience-dependent plasticity in the mouse visual cortex. In the present study, we investigated the role of keratan sulfate (KS), another glycosaminoglycan, in critical period plasticity in the mouse visual cortex. Immunohistochemical analyses demonstrated the presence of KS containing disaccharide units of N-acetylglucosamine (GlcNAc)-6-sulfate and nonsulfated galactose during the critical period, although KS containing disaccharide units of GlcNAc-6-sulfate and galactose-6-sulfate was already known to disappear before that period. The KS chains were distributed diffusely in the extracellular space and densely around the soma of a large population of excitatory and inhibitory neurons. Electron microscopic analysis revealed that the KS was localized within the perisynaptic spaces and dendrites but not in presynaptic sites. KS was mainly located on phosphacan. In mice deficient in GlcNAc-6-O-sulfotransferase 1, which is one of the enzymes necessary for the synthesis of KS chains, the expression of KS was one half that in wild-type mice. In the knockout mice, monocular deprivation during the critical period resulted in a depression of deprived-eye responses but failed to produce potentiation of nondeprived-eye responses. In addition, T-type Ca(2+) channel-dependent long-term potentiation (LTP), which occurs only during the critical period, was not observed. These results suggest that regulation by KS-phosphacan with a specific sulfation pattern is necessary for the generation of LTP and hence the potentiation of nondeprived-eye responses after monocular deprivation.

  12. Flow injection spectrophotometry coupled with a crushed barium sulfate reactor column for the determination of sulfate ion in water samples

    OpenAIRE

    Burakham,Rodjana; Higuchi, Keiro; Oshima, Mitsuko; Grudpan, Kate; Motomizu, Shoji

    2004-01-01

    A new type of a reactor column, a crushed BaSO4 reactor column used for the flow injection spectrophotometric determination of sulfate ion using the exchange reaction of sulfate ion and barium-dimethylsulfonazo III is proposed. The column is very simple and economical. It can be continuously used for 8 h before washing with water for repeated usage of at least 1 month. The procedure is sensitive. Application to various water samples was demonstrated.

  13. Dockomatic - automated ligand creation and docking

    Directory of Open Access Journals (Sweden)

    Hampikian Greg

    2010-11-01

    Full Text Available Abstract Background The application of computational modeling to rationally design drugs and characterize macro biomolecular receptors has proven increasingly useful due to the accessibility of computing clusters and clouds. AutoDock is a well-known and powerful software program used to model ligand to receptor binding interactions. In its current version, AutoDock requires significant amounts of user time to setup and run jobs, and collect results. This paper presents DockoMatic, a user friendly Graphical User Interface (GUI application that eases and automates the creation and management of AutoDock jobs for high throughput screening of ligand to receptor interactions. Results DockoMatic allows the user to invoke and manage AutoDock jobs on a single computer or cluster, including jobs for evaluating secondary ligand interactions. It also automates the process of collecting, summarizing, and viewing results. In addition, DockoMatic automates creation of peptide ligand .pdb files from strings of single-letter amino acid abbreviations. Conclusions DockoMatic significantly reduces the complexity of managing multiple AutoDock jobs by facilitating ligand and AutoDock job creation and management.

  14. Dockomatic - automated ligand creation and docking.

    Science.gov (United States)

    Bullock, Casey W; Jacob, Reed B; McDougal, Owen M; Hampikian, Greg; Andersen, Tim

    2010-11-08

    The application of computational modeling to rationally design drugs and characterize macro biomolecular receptors has proven increasingly useful due to the accessibility of computing clusters and clouds. AutoDock is a well-known and powerful software program used to model ligand to receptor binding interactions. In its current version, AutoDock requires significant amounts of user time to setup and run jobs, and collect results. This paper presents DockoMatic, a user friendly Graphical User Interface (GUI) application that eases and automates the creation and management of AutoDock jobs for high throughput screening of ligand to receptor interactions. DockoMatic allows the user to invoke and manage AutoDock jobs on a single computer or cluster, including jobs for evaluating secondary ligand interactions. It also automates the process of collecting, summarizing, and viewing results. In addition, DockoMatic automates creation of peptide ligand .pdb files from strings of single-letter amino acid abbreviations. DockoMatic significantly reduces the complexity of managing multiple AutoDock jobs by facilitating ligand and AutoDock job creation and management.

  15. Sliding tethered ligands add topological interactions to the toolbox of ligand-receptor design

    Science.gov (United States)

    Bauer, Martin; Kékicheff, Patrick; Iss, Jean; Fajolles, Christophe; Charitat, Thierry; Daillant, Jean; Marques, Carlos M.

    2015-09-01

    Adhesion in the biological realm is mediated by specific lock-and-key interactions between ligand-receptor pairs. These complementary moieties are ubiquitously anchored to substrates by tethers that control the interaction range and the mobility of the ligands and receptors, thus tuning the kinetics and strength of the binding events. Here we add sliding anchoring to the toolbox of ligand-receptor design by developing a family of tethered ligands for which the spacer can slide at the anchoring point. Our results show that this additional sliding degree of freedom changes the nature of the adhesive contact by extending the spatial range over which binding may sustain a significant force. By introducing sliding tethered ligands with self-regulating length, this work paves the way for the development of versatile and reusable bio-adhesive substrates with potential applications for drug delivery and tissue engineering.

  16. A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

    KAUST Repository

    Li, Huaifeng

    2014-12-01

    Work on a new class of PN3-pincer ligands for metal-ligand cooperative catalysis is reviewed. While the field of the pyridine-based PN3-transition metal pincer complexes is still relatively young, many important applications of these complexes have already emerged. In several cases, the PN3-pincer complexes for metal-ligand cooperative catalysis result in significantly improved or unprecedented activities. The synthesis and coordination chemistry of PN3-pincer ligands are briefly summarized first to cover the synthetic routes for their preparation, followed by a focus review on their applications in catalysis. A specific emphasis is placed on the later section about the role of PN3-pincer ligands\\' dearomatization-rearomatization steps during the catalytic cycles. The mechanistic insights from density functional theory (DFT) calculations are also discussed.

  17. Characteristics of Phosphorus in Some Eastern Australian Acid Sulfate Soils

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Forty-five acid sulfate topsoil samples (depth < 0.5 m) from 15 soil cores were collected from 11 locations along the New South Wales coast, Australia. There was an overall trend for the concentration of the HC1extractable P to increase along with increasing amounts of organic C and the HCl-extractable trivalent metals in the topsoils of some less-disturbed acid sulfate soils (pH <4.5). This suggests that inorganic P in these soils probably accumulated via biological cycling and was retained by complexation with trivalent metals or their oxides and hydroxides. While there was no clear correlation between pH and the water-extractable P, the concentration of the water-extractable P tended to increase with increasing amounts of the HCl-extractable P. This disagrees with some established models which suggest that the concentration of solution P in acid soils is independent of total P and decreases with increasing acidity. The high concentration of sulfate present in acid sulfate soils appeared to affect the chemical behavior of P in these soil systems. Comparison was made between a less disturbed wetland acid sulfate soil and a more intensively disturbed sugarcane acid sulfate soil.The results show that reclamation of wetland acid sulfate soils for sugarcane production caused a significant decrease in the HCl-extractable P in the topsoil layer as a result of the reduced bio-cycling of phosphorus following sugarcane farming. Simulation experiment shows that addition of hydrated lime had no effects on the immobilization of retained P in an acid sulfate soil sample within a pH range 3.5~4.6. When the pH was raised to above 4.6, soluble P in the soil extracts had a tendency to increase with increasing pH until the 15th extraction (pH 5.13). This, in combination with the poor pH-soluble P relationship observed from the less-disturbed acid sulfate soils, suggests that soluble P was not clearly pH-dependent in acid sulfate soils with pH < 4.5.

  18. Identification of keratan sulfate disaccharide at C-3 position of glucuronate of chondroitin sulfate from Mactra chinensis

    Science.gov (United States)

    Higashi, Kyohei; Takeda, Keita; Mukuno, Ann; Okamoto, Yusuke; Masuko, Sayaka; Linhardt, Robert J.; Toida, Toshihiko

    2016-01-01

    Glycosaminoglycans (GAGs), including chondroitin sulfate (CS), dermatan sulfate, heparin, heparan sulfate and keratan sulfate (KS) are linear sulfated repeating disaccharide sequences containing hexosamine and uronic acid [or galactose (Gal) in the case of KS]. Among the GAGs, CS shows structural variations, such as sulfation patterns and fucosylation, which are responsible for their physiological functions through CS interaction with CS-binding proteins. Here, we solved the structure of KS-branched CS-E derived from a clam, Mactra chinensis. KS disaccharide [d-GlcNAc6S-(1→3)-β-d-Gal-(1→] was attached to the C-3 position of GlcA, and consecutive KS-branched disaccharide sequences were found in a CS chain. KS-branched polysaccharides clearly exhibited resistance to degradation by chondroitinase ABC or ACII (at low concentrations) compared with typical CS structures. Furthermore, KS-branched polysaccharides stimulated neurite outgrowth of hippocampal neurons. These results strongly suggest that M. chinensis is a rich source of KS-branched CS, and it has important biological activities. PMID:27647934

  19. Synthesis and Structures of Two Lanthanide Complexes Containing a Mixed Ligand System: [Ln(Phen){sub 2}(L){sub 3}(HL)]·H{sub 2}O [Ln = La, Ce; Phen = Phenanthroline; HL = Salicylic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Iravani, Effat [UNiv. of Applied Science and Technology, Tehran (Iran, Islamic Republic of); Nami, Navabeh; Nabizadeh, Fatemeh; Bayani, Elham [Islamic Azad Univ., Mazandaran (Iran, Islamic Republic of); Neumueller, Bernhard [Philipps-Universitat Marburg, Marburg (Germany)

    2013-11-15

    The reaction of LnCl{sub 3}·7H{sub 2}O [Ln = La (1), Ce (2)] with salicylic acid (HL) and 1,10-phenanthroline (Phen) at 20 .deg. C in H{sub 2}O/ethanol gave after work-up and recrystallization two novel lanthanide complexes with general formula [Ln(Phen){sub 2}(L){sub 3}(HL)]·H{sub 2}O. Compounds 1 and 2 were characterized by IR and UV-Vis spectroscopy, TGA, CHN as well as by X-ray analysis. According to these results, compounds 1 and 2 are isostructural and contain Ln{sup 3+} ions with coordination number nine. Complexes 1 and 2 consist of two Phen, one neutral HL and three L anions (two L anions act as monodentate ligands and the third one is chelating to Ln{sup 3+}). Thermal decomposition led to primary loss of the Phen molecules. Then HL molecules and finally L moieties left the material to give Ln{sub 2}O{sub 3}.

  20. Sulfation of deoxynivalenol, its acetylated derivatives, and T2-toxin ☆

    OpenAIRE

    Fruhmann, Philipp; Skrinjar, Philipp; Weber, Julia; Mikula, Hannes; Warth, Benedikt; Sulyok, Michael; Krska, Rudolf; Adam, Gerhard; Erwin ROSENBERG; Hametner, Christian; Fröhlich, Johannes

    2014-01-01

    The synthesis of several sulfates of trichothecene mycotoxins is presented. Deoxynivalenol (DON) and its acetylated derivatives were synthesized from 3-acetyldeoxynivalenol (3ADON) and used as substrate for sulfation in order to reach a series of five different DON-based sulfates as well as T2-toxin-3-sulfate. These substances are suspected to be formed during phase-II metabolism in plants and humans. The sulfation was performed using a sulfuryl imidazolium salt, which was synthesized prior t...

  1. Olivine Weathering aud Sulfate Formation Under Cryogenic Conditions

    Science.gov (United States)

    Niles, Paul B.; Golden, D. C.; Michalski, J.

    2013-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one of the most important discoveries being wide-spread layered sedimentary deposits associated with sulfate minerals across the low to mid latitude regions of Mars. The mechanism for sulfate formation on Mars has been frequently attributed to playa-like evaporative environments under prolonged warm conditions. An alternate view of the ancient martian climate contends that prolonged warm temperatures were never present and that the atmosphere and climate has been similar to modern conditions throughout most of its history. This view has had a difficult time explaining the sedimentary history of Mars and in particular the presence of sulfate minerals which seemingly need more water. We suggest here that mixtures of atmospheric aerosols, ice, and dust have the potential for creating small films of cryo-concentrated acidic solutions that may represent an important unexamined environment for understanding weathering processes on Mars. This study seeks to test whether sulfate formation may be possible at temperatures well below 0degC in water limited environments removing the need for prolonged warm periods to form sulfates on early Mars. To test this idea we performed laboratory experiments to simulate weathering of mafic minerals under Mars-like conditions. The weathering rates measured in this study suggest that fine grained olivine on Mars would weather into sulfate minerals in short time periods if they are exposed to H2SO4 aerosols at temperatures at or above -40degC. In this system, the strength of the acidic solution is maximized through eutectic freezing in an environment where the silicate minerals are extremely fine grained and have high surface areas. This provides an ideal environment despite the very low temperatures. On Mars the presence of large deposits of mixed ice and dust is undisputed. The presence of substantial

  2. Cationic ruthenium alkylidene catalysts bearing phosphine ligands.

    Science.gov (United States)

    Endo, Koji; Grubbs, Robert H

    2016-02-28

    The discovery of highly active catalysts and the success of ionic liquid immobilized systems have accelerated attention to a new class of cationic metathesis catalysts. We herein report the facile syntheses of cationic ruthenium catalysts bearing bulky phosphine ligands. Simple ligand exchange using silver(i) salts of non-coordinating or weakly coordinating anions provided either PPh3 or chelating Ph2P(CH2)nPPh2 (n = 2 or 3) ligated cationic catalysts. The structures of these newly reported catalysts feature unique geometries caused by ligation of the bulky phosphine ligands. Their activities and selectivities in standard metathesis reactions were also investigated. These cationic ruthenium alkylidene catalysts reported here showed moderate activity and very similar stereoselectivity when compared to the second generation ruthenium dichloride catalyst in ring-closing metathesis, cross metathesis, and ring-opening metathesis polymerization assays.

  3. Flexible Ligand Docking Using Evolutionary Algorithms

    DEFF Research Database (Denmark)

    Thomsen, Rene

    2003-01-01

    The docking of ligands to proteins can be formulated as a computational problem where the task is to find the most favorable energetic conformation among the large space of possible protein–ligand complexes. Stochastic search methods such as evolutionary algorithms (EAs) can be used to sample large...... search spaces effectively and is one of the commonly used methods for flexible ligand docking. During the last decade, several EAs using different variation operators have been introduced, such as the ones provided with the AutoDock program. In this paper we evaluate the performance of different EA...... settings such as choice of variation operators, population size, and usage of local search. The comparison is performed on a suite of six docking problems previously used to evaluate the performance of search algorithms provided with the AutoDock program package. The results from our investigation confirm...

  4. A statistical experimental design to remove sulfate by crystallization in a fluidized-bed reactor

    Directory of Open Access Journals (Sweden)

    Mark Daniel G. de Luna

    2017-05-01

    Full Text Available This study used crystallization in a fluidized-bed reactor as an alternative technology to the conventional chemical precipitation to remove sulfate. The Box-Behnken Design was used to study the effects and interactions of seed dosage of synthetic gypsum, initial sulfate concentration and molar ratio of calcium to sulfate on conversion and removal of sulfate. The optimum conditions of conversion and removal of sulfate were determined and used to treat the simulated acid mine drainage (AMD wastewater. The effect of inorganic ions CO32−, NH4+ and Al3+ on sulfate conversion was also investigated. Experimental results indicated that seed dosage, initial sulfate concentration and molar ratio of calcium to sulfate are all significant parameters in the sulfate removal by fluidized-bed crystallization. The optimal conditions of 4 g seed L−1, 119.7 mM of initial sulfate concentration and [Ca2+]/[SO42−] molar ratio of 1.48 resulted in sulfate conversion of 82% and sulfate removal of 67%. Conversion and removal of sulfate in the simulated AMD wastewater were 79 and 63%, respectively. When ammonium or aluminum was added to the synthetic sulfate wastewater, significant conversion of sulfate was achieved.

  5. Revisiting Modes of energy generation in sulfate reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Joachimiak, Marcin; Chakraborty, Romy; Zhou, Aifen; Fortney, Julian; Geller, Jil; Wall, Judy; Zhou, Jizhong; Arkin, Adam; Hazen, Terry; Keasling, Jay; Chhabra, Swapnil

    2010-05-17

    Sulfate reducing bacteria (SRB) play an important role in global sulfur and carbon cycling through their ability to completely mineralize organic matter while respiring sulfate to hydrogen sulfide. They are ubiquitous in anaerobic environments and have the ability to reduce toxic metals like Cr(VI) and U(VI). While SRB have been studied for over three decades, bioenergetic modes of this group of microbes are poorly understood. Desulfovibrio vulgaris strain Hildenborough (DvH) has served as a model SRB over the last decade with the accumulation of transcriptomic, proteomic and metabolic data under a wide variety of stressors. To further investigate the three hypothesized modes of energy generation in this anaerobe we conducted a systematic study involving multiple electron donor and acceptor combinations for growth. DvH was grown at 37oC in a defined medium with (a) lactate + thiosulfate, (b) lactate + sulfite (c) lactate + sulfate, (d) pyruvate + sulfate, (e) H2 + acetate + sulfate, (f) formate + acetate + sulfate, g) formate + sulfate and (h) pyruvate fermentation. Cells were harvested at mid-log phase of growth for all conditions for transcriptomics, when the optical density at 600nm was in the range 0.42-0.5. Initial results indicate that cells grown on lactate do not appear to significantly differentiate their gene expression profiles when presented with different electron acceptors. These profiles however differ significantly from those observed during growth with other electron donors such as H2 and formate, as well as during fermentative growth. Together the gene expression changes in the presence of different electron donors provide insights into the ability of DvH to differentially reduce metals such as Cr(VI). Here we present revised modes of energy generation in DvH in light of this new transcriptomic evidence.

  6. Revisiting Modes of energy generation in sulfate reducing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Joachimiak, Marcin; Chakraborty, Romy; Zhou, Aifen; Fortney, Julian; Geller, Jil; Wall, Judy; Zhou, Jizhong; Arkin, Adam; Hazen, Terry; Keasling, Jay; Chhabra, Swapnil

    2010-05-17

    Sulfate reducing bacteria (SRB) play an important role in global sulfur and carbon cycling through their ability to completely mineralize organic matter while respiring sulfate to hydrogen sulfide. They are ubiquitous in anaerobic environments and have the ability to reduce toxic metals like Cr(VI) and U(VI). While SRB have been studied for over three decades, bioenergetic modes of this group of microbes are poorly understood. Desulfovibrio vulgaris strain Hildenborough (DvH) has served as a model SRB over the last decade with the accumulation of transcriptomic, proteomic and metabolic data under a wide variety of stressors. To further investigate the three hypothesized modes of energy generation in this anaerobe we conducted a systematic study involving multiple electron donor and acceptor combinations for growth. DvH was grown at 37oC in a defined medium with (a) lactate + thiosulfate, (b) lactate + sulfite (c) lactate + sulfate, (d) pyruvate + sulfate, (e) H2 + acetate + sulfate, (f) formate + acetate + sulfate, g) formate + sulfate and (h) pyruvate fermentation. Cells were harvested at mid-log phase of growth for all conditions for transcriptomics, when the optical density at 600nm was in the range 0.42-0.5. Initial results indicate that cells grown on lactate do not appear to significantly differentiate their gene expression profiles when presented with different electron acceptors. These profiles however differ significantly from those observed during growth with other electron donors such as H2 and formate, as well as during fermentative growth. Together the gene expression changes in the presence of different electron donors provide insights into the ability of DvH to differentially reduce metals such as Cr(VI). Here we present revised modes of energy generation in DvH in light of this new transcriptomic evidence.

  7. Anaerobic degradation of citrate under sulfate reducing and methanogenic conditions.

    Science.gov (United States)

    Gámez, Victor M; Sierra-Alvarez, Reyes; Waltz, Rebecca J; Field, James A

    2009-07-01

    Citrate is an important component of metal processing effluents such as chemical mechanical planarization wastewaters of the semiconductor industry. Citrate can serve as an electron donor for sulfate reduction applied to promote the removal of metals, and it can also potentially be used by methanogens that coexist in anaerobic biofilms. The objective of this study was to evaluate the degradation of citrate with sulfate-reducing and methanogenic biofilms. During batch bioassays, the citrate, acetate, methane and sulfide concentrations were monitored. The results indicate that independent of the biofilm or incubation conditions used, citrate was rapidly fermented with specific rates ranging from 566 to 720 mg chemical oxygen demand (COD) consumed per gram volatile suspended solids per day. Acetate was found to be the main fermentation product of citrate degradation, which was later degraded completely under either methanogenic or sulfate reducing conditions. However, if either sulfate reduction or methanogenesis was infeasible due to specific inhibitors (2-bromoethane sulfonate), absence of sulfate or lack of adequate microorganisms in the biofilm, acetate accumulated to levels accounting for 90-100% of the citrate-COD consumed. Based on carbon balances measured in phosphate buffered bioassays, acetate, CO(2) and hydrogen are the main products of citrate fermentation, with a molar ratio of 2:2:1 per mol of citrate, respectively. In bicarbonate buffered bioassays, acetogenesis of H(2) and CO(2) increased the yield of acetate. The results taken as a whole suggest that in anaerobic biofilm systems, citrate is metabolized via the formation of acetate as the main metabolic intermediate prior to methanogenesis or sulfate reduction. Sulfate reducing consortia must be enriched to utilize acetate as an electron donor in order to utilize the majority of the electron-equivalents in citrate.

  8. Annual sulfate budgets for Dutch lowland peat polders: The soil is a major sulfate source through peat and pyrite oxidation

    Science.gov (United States)

    Vermaat, Jan E.; Harmsen, Joop; Hellmann, Fritz A.; van der Geest, Harm G.; de Klein, Jeroen J. M.; Kosten, Sarian; Smolders, Alfons J. P.; Verhoeven, Jos T. A.; Mes, Ron G.; Ouboter, Maarten

    2016-02-01

    Annual sulfate mass balances have been constructed for four low-lying peat polders in the Netherlands, to resolve the origin of high sulfate concentrations in surface water, which is considered a water quality problem, as indicated amongst others by the absence of sensitive water plant species. Potential limitation of these plants to areas with low sulfate was analyzed with a spatial match-up of two large databases. The peat polders are generally used for dairy farming or nature conservation, and have considerable areas of shallow surface water (mean 16%, range 6-43%). As a consequence of continuous drainage, the peat in these polders mineralizes causing subsidence rates generally ranging between 2 and 10 mm y-1. Together with pyrite oxidation, this peat mineralization the most important internal source of sulfate, providing an estimated 96 kg SO4 ha-1 mm-1 subsidence y-1. External sources are precipitation and water supplied during summer to compensate for water shortage, but these were found to be minor compared to internal release. The most important output flux is discharge of excess surface water during autumn and winter. If only external fluxes in and out of a polder are evaluated, inputs average 37 ± 9 and exports 169 ± 17 kg S ha-1 y-1. During summer, when evapotranspiration exceeds rainfall, sulfate accumulates in the unsaturated zone, to be flushed away and drained off during the wet autumn and winter. In some polders, upward seepage from early Holocene, brackish sediments can be a source of sulfate. Peat polders export sulfate to the regional water system and the sea during winter drainage. The available sulfate probably only plays a minor role in the oxidation of peat: we estimate that this is less than 10% whereas aerobic mineralization is the most important. Most surface waters in these polders have high sulfate concentrations, which generally decline during the growing season when aquatic sediments are a sink. In the sediment, this sulfur is

  9. Ligand Intermediates in Metal-Catalyzed Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Gladysz, John A.

    1999-07-31

    The longest-running goal of this project has been the synthesis, isolation, and physical chemical characterization of homogeneous transition metal complexes containing ligand types believed to be intermediates in the metal-catalyzed conversion of CO/H{sub 2}, CO{sub 2}, CH{sub 4}, and similar raw materials to organic fuels, feedstocks, etc. In the current project period, complexes that contain unusual new types of C{sub x}(carbide) and C{sub x}O{sub y} (carbon oxide) ligands have been emphasized. A new program in homogeneous fluorous phase catalysis has been launched as described in the final report.

  10. Efficient chemoenzymatic synthesis of chiral pincer ligands.

    Science.gov (United States)

    Felluga, Fulvia; Baratta, Walter; Fanfoni, Lidia; Pitacco, Giuliana; Rigo, Pierluigi; Benedetti, Fabio

    2009-05-01

    Chiral, nonracemic pincer ligands based on the 6-phenyl-2-aminomethylpyridine and 2-aminomethylbenzo[h]quinoline scaffolds were obtained by a chemoenzymatic approach starting from 2-pyridyl and 2-benzoquinolyl ethanone. In the enantiodifferentiating step, secondary alcohols of opposite absolute configuration were obtained by a baker's yeast reduction of the ketones and by lipase-mediated dynamic kinetic resolution of the racemic alcohols. Their transformation into homochiral 1-methyl-1-heteroarylethanamines occurred without loss of optical purity, giving access to pincer ligands used in enantioselective catalysis.

  11. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent : Part I. the absorption of hydrogen sulfide in metal sulfate solutions

    NARCIS (Netherlands)

    Ter Maat, H.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    The desulfurization of gas streams using aqueous iron(II)sulfate (Fe(II)SO4), zinc sulfate (ZnSO4) and copper sulfate (CuSO4) solutions as washing liquor is studied theoretically and experimentally. The desulfurization is accomplished by a precipitation reaction that occurs when sulfide ions and met

  12. The removal of hydrogen sulfide from gas streams using an aqueous metal sulfate absorbent : Part I. the absorption of hydrogen sulfide in metal sulfate solutions

    NARCIS (Netherlands)

    Ter Maat, H.; Hogendoorn, J. A.; Versteeg, G. F.

    2005-01-01

    The desulfurization of gas streams using aqueous iron(II)sulfate (Fe(II)SO4), zinc sulfate (ZnSO4) and copper sulfate (CuSO4) solutions as washing liquor is studied theoretically and experimentally. The desulfurization is accomplished by a precipitation reaction that occurs when sulfide ions and

  13. Silver(I nitrate complexes of three tetrakis-thioether-substituted pyrazine ligands: metal–organic chain, network and framework structures

    Directory of Open Access Journals (Sweden)

    Tokouré Assoumatine

    2017-03-01

    Full Text Available The reaction of the ligand 2,3,5,6-tetrakis[(methylsulfanylmethyl]pyrazine (L1 with silver(I nitrate led to {[Ag(C12H20N2S4](NO3}n, (I, catena-poly[[silver(I-μ-2,3,5,6-tetrakis[(methylsulfanylmethyl]pyrazine] nitrate], a compound with a metal–organic chain structure. The asymmetric unit is composed of two half ligands, located about inversion centres, with one ligand coordinating to the silver atoms in a bis-tridentate manner and the other in a bis-bidentate manner. The charge on the metal atom is compensated for by a free nitrate anion. Hence, the silver atom has a fivefold S3N2 coordination sphere. The reaction of the ligand 2,3,5,6-tetrakis[(phenylsulfanylmethyl]pyrazine (L2 with silver(I nitrate, led to [Ag2(NO32(C32H28N2S4]n, (II, poly[di-μ-nitrato-bis{μ-2,3,5,6-tetrakis[(phenylsulfanylmethyl]pyrazine}disilver], a compound with a metal–organic network structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. The nitrate anion coordinates to the silver atom in a bidentate/monodentate manner, bridging the silver atoms, which therefore have a sixfold S2NO3 coordination sphere. The reaction of the ligand 2,3,5,6-tetrakis[(pyridin-2-ylsulfanylmethyl]pyrazine (L3 with silver(I nitrate led to [Ag3(NO33(C28H24N6S4]n, (III, poly[trinitrato{μ6-2,3,5,6-tetrakis[(pyridin-2-ylsulfanylmethyl]pyrazine}trisilver(I], a compound with a metal–organic framework structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. One pyridine N atom bridges the monomeric units, so forming a chain structure. Two nitrate O atoms also coordinate to this silver atom, hence it has a sixfold S2N2O2 coordination sphere. The chains are linked via a second silver atom, located on a twofold rotation axis, coordinated by the second pyridine N atom. A second nitrate anion

  14. CLiBE: a database of computed ligand binding energy for ligand-receptor complexes.

    Science.gov (United States)

    Chen, X; Ji, Z L; Zhi, D G; Chen, Y Z

    2002-11-01

    Consideration of binding competitiveness of a drug candidate against natural ligands and other drugs that bind to the same receptor site may facilitate the rational development of a candidate into a potent drug. A strategy that can be applied to computer-aided drug design is to evaluate ligand-receptor interaction energy or other scoring functions of a designed drug with that of the relevant ligands known to bind to the same binding site. As a tool to facilitate such a strategy, a database of ligand-receptor interaction energy is developed from known ligand-receptor 3D structural entries in the Protein Databank (PDB). The Energy is computed based on a molecular mechanics force field that has been used in the prediction of therapeutic and toxicity targets of drugs. This database also contains information about ligand function and other properties and it can be accessed at http://xin.cz3.nus.edu.sg/group/CLiBE.asp. The computed energy components may facilitate the probing of the mode of action and other profiles of binding. A number of computed energies of some PDB ligand-receptor complexes in this database are studied and compared to experimental binding affinity. A certain degree of correlation between the computed energy and experimental binding affinity is found, which suggests that the computed energy may be useful in facilitating a qualitative analysis of drug binding competitiveness.

  15. Combinatorial roles of heparan sulfate proteoglycans and heparan sulfates in Caenorhabditis elegans neural development.

    Directory of Open Access Journals (Sweden)

    Tarja K Kinnunen

    Full Text Available Heparan sulfate proteoglycans (HSPGs play critical roles in the development and adult physiology of all metazoan organisms. Most of the known molecular interactions of HSPGs are attributed to the structurally highly complex heparan sulfate (HS glycans. However, whether a specific HSPG (such as syndecan contains HS modifications that differ from another HSPG (such as glypican has remained largely unresolved. Here, a neural model in C. elegans is used to demonstrate for the first time the relationship between specific HSPGs and HS modifications in a defined biological process in vivo. HSPGs are critical for the migration of hermaphrodite specific neurons (HSNs as genetic elimination of multiple HSPGs leads to 80% defect of HSN migration. The effects of genetic elimination of HSPGs are additive, suggesting that multiple HSPGs, present in the migrating neuron and in the matrix, act in parallel to support neuron migration. Genetic analyses suggest that syndecan/sdn-1 and HS 6-O-sulfotransferase, hst-6, function in a linear signaling pathway and glypican/lon-2 and HS 2-O-sulfotransferase, hst-2, function together in a pathway that is parallel to sdn-1 and hst-6. These results suggest core protein specific HS modifications that are critical for HSN migration. In C. elegans, the core protein specificity of distinct HS modifications may be in part regulated at the level of tissue specific expression of genes encoding for HSPGs and HS modifying enzymes. Genetic analysis reveals that there is a delicate balance of HS modifications and eliminating one HS modifying enzyme in a compromised genetic background leads to significant changes in the overall phenotype. These findings are of importance with the view of HS as a critical regulator of cell signaling in normal development and disease.

  16. Sulfate Hydration States in Interpretation of Martian Mineral Assemblages

    Science.gov (United States)

    Vaniman, D. T.; Bish, D. L.

    2008-12-01

    Remote spectral data and surface-measured chemical associations with S indicate widespread distribution of Mg-, Ca-, and Fe-sulfate salts on Mars. These salts are identified at least in part as hydrates, but spectral data and the low temperatures and low pH2O of Mars suggest that hydration states vary with origin, latitude, and exposure history. An understanding of stability limits and dehydration/rehydration rates is vital to understanding occurrences that may be interpreted variously as lacustrine, alteration via groundwater or discharge with evaporation, surface weathering, thermal brine systems, eolian recycling, or others. Different sulfates on Mars have varied susceptibility to desiccation at relatively warm, low-RH conditions or to hydration at cold, high-RH conditions. This variability provides a potent tool for interpreting exposure history. Among Ca-sulfates, gypsum and insoluble anhydrite should be stable and remain, respectively, fully hydrated or water-free at most latitudes and through diurnal and seasonal cycles, but bassanite is more sensitive to transient hydration. Mg-sulfates may have various values of n in the formula MgSO4.nH2O, and rehydration of desiccated forms often produces metastable phases. At low pH2O, unlike Ca- sulfates, amorphous forms appear with low values of n dependent, in part, on temperature. Kieserite resists dehydration but may hydrate in conditions where ice is stable at the surface. Fe-sulfates have more complex dehydration and rehydration properties. Jarosite is very resilient because of the lack of H2O molecules and presence of OH. Other Fe-sulfates are not so durable, e.g., coquimbite (Fe2 (SO4)3.9H2O) has independent H2O and dehydration on heating to 30 °C produces an amorphous product that does not rehydrate. Copiapite is similarly susceptible to dehydration. Modest heating of many H2O-bearing ferric sulfates can be destructive, and degradation can produce both cemented solids and viscous liquids. Sulfate salt

  17. Development of cell-based bioassay with Sf9 cells expressing TcSKR1 and TcSKR2 and differential activation by sulfated and non-sulfated SK peptides.

    Science.gov (United States)

    Yu, Na; Swevers, Luc; Nachman, Ronald J; Smagghe, Guy

    2014-03-01

    Insect sulfakinin receptors (SKRs) are G-protein-coupled receptors (GPCRs) that interact with sulfakinins (SKs) to modulate diverse biological processes. One of the indispensable roles of SKs is in the regulation of food intake in insects. In this project we report on the development of a cell-based receptor assay system with insect Sf9 cells, expressing TcSKR1 and TcSKR2 from the red flour beetle Tribolium castaneum, a model and important pest insect in agriculture. In this system, a stable presence of the two TcSKRs was supported by Western blotting. The expressed TcSKRs were coupled to Gαs-protein upon activation and stimulated cAMP accumulation in Sf9 cells. Exposure of the transfected cell lines to sulfated SK (sSK) activated TcSKR1 at 1 nM; the EC50 of sSK to obtain 50% of receptor activation was similar for both receptors. In contrast, μM concentrations of non-sulfated SK were necessary to activate both TcSKRs. In conclusion, this cell-based TcSKR assay system is useful to screen SK-related peptides and mimetics and to better document ligand-receptor structure-activity relationships. Given the importance of SK signaling system in insects, the present study may provide new insights on the development of new methods to control pest insects.

  18. Nickel, manganese and copper removal by a mixed consortium of sulfate reducing bacteria at a high COD/sulfate ratio.

    Science.gov (United States)

    Barbosa, L P; Costa, P F; Bertolino, S M; Silva, J C C; Guerra-Sá, R; Leão, V A; Teixeira, M C

    2014-08-01

    The use of sulfate-reducing bacteria (SRB) in passive treatments of acidic effluents containing heavy metals has become an attractive alternative biotechnology. Treatment efficiency may be linked with the effluent conditions (pH and metal concentration) and also to the amount and nature of the organic substrate. Variations on organic substrate and sulfate ratios clearly interfere with the biological removal of this ion by mixed cultures of SRB. This study aimed to cultivate a mixed culture of SRB using different lactate concentrations at pH 7.0 in the presence of Ni, Mn and Cu. The highest sulfate removal efficiency obtained was 98 %, at a COD/sulfate ratio of 2.0. The organic acid analyses indicated an acetate accumulation as a consequence of lactate degradation. Different concentrations of metals were added to the system at neutral pH conditions. Cell proliferation and sulfate consumption in the presence of nickel (4, 20 and 50 mg l(-1)), manganese (1.5, 10 and 25 mg l(-1)) and copper (1.5, 10 and 25 mg l(-1)) were measured. The presence of metals interfered in the sulfate biological removal however the concentration of sulfide produced was high enough to remove over 90 % of the metals in the environment. The molecular characterization of the bacterial consortium based on dsrB gene sequencing indicated the presence of Desulfovibrio desulfuricans, Desulfomonas pigra and Desulfobulbus sp. The results here presented indicate that this SRB culture may be employed for mine effluent bioremediation due to its potential for removing sulfate and metals, simultaneously.

  19. Tyrosine Sulfation as a Protein Post-Translational Modification

    Directory of Open Access Journals (Sweden)

    Yuh-Shyong Yang

    2015-01-01

    Full Text Available Integration of inorganic sulfate into biological molecules plays an important role in biological systems and is directly involved in the instigation of diseases. Protein tyrosine sulfation (PTS is a common post-translational modification that was first reported in the literature fifty years ago. However, the significance of PTS under physiological conditions and its link to diseases have just begun to be appreciated in recent years. PTS is catalyzed by tyrosylprotein sulfotransferase (TPST through transfer of an activated sulfate from 3'-phosphoadenosine-5'-phosphosulfate to tyrosine in a variety of proteins and peptides. Currently, only a small fraction of sulfated proteins is known and the understanding of the biological sulfation mechanisms is still in progress. In this review, we give an introductory and selective brief review of PTS and then summarize the basic biochemical information including the activity and the preparation of TPST, methods for the determination of PTS, and kinetics and reaction mechanism of TPST. This information is fundamental for the further exploration of the function of PTS that induces protein-protein interactions and the subsequent biochemical and physiological reactions.

  20. Is Encephalopathy a Mechanism to Renew Sulfate in Autism?

    Directory of Open Access Journals (Sweden)

    Laurie Lentz-Marino

    2013-01-01

    Full Text Available This paper makes two claims: (1 autism can be characterized as a chronic low-grade encephalopathy, associated with excess exposure to nitric oxide, ammonia and glutamate in the central nervous system, which leads to hippocampal pathologies and resulting cognitive impairment, and (2, encephalitis is provoked by a systemic deficiency in sulfate, but associated seizures and fever support sulfate restoration. We argue that impaired synthesis of cholesterol sulfate in the skin and red blood cells, catalyzed by sunlight and nitric oxide synthase enzymes, creates a state of colloidal instability in the blood manifested as a low zeta potential and increased interfacial stress. Encephalitis, while life-threatening, can result in partial renewal of sulfate supply, promoting neuronal survival. Research is cited showing how taurine may not only help protect neurons from hypochlorite exposure, but also provide a source for sulfate renewal. Several environmental factors can synergistically promote the encephalopathy of autism, including the herbicide, glyphosate, aluminum, mercury, lead, nutritional deficiencies in thiamine and zinc, and yeast overgrowth due to excess dietary sugar. Given these facts, dietary and lifestyle changes, including increased sulfur ingestion, organic whole foods, increased sun exposure, and avoidance of toxins such as aluminum, mercury, and lead, may help to alleviate symptoms or, in some instances, to prevent autism altogether.