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Sample records for nitrosyl iron complexes

  1. Nitrosylation of Nitric-Oxide-Sensing Regulatory Proteins Containing [4Fe-4S] Clusters Gives Rise to Multiple Iron-Nitrosyl Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Pauline N. [Department of Chemistry, University of California, Davis CA 95616 USA; Wang, Hongxin [Department of Chemistry, University of California, Davis CA 95616 USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA; Crack, Jason C. [Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park Norwich NR4 7TJ UK; Prior, Christopher [Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park Norwich NR4 7TJ UK; Hutchings, Matthew I. [School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ UK; Thomson, Andrew J. [Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park Norwich NR4 7TJ UK; Kamali, Saeed [University of Tennessee Space Institute, Tullahome TN 37388-9700 USA; Yoda, Yoshitaka [Research and Utilization Division, SPring-8/JASRI, 1-1-1 Kouto, Sayo Hyogo 679-5198 Japan; Zhao, Jiyong [Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Hu, Michael Y. [Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Alp, Ercan E. [Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Oganesyan, Vasily S. [Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park Norwich NR4 7TJ UK; Le Brun, Nick E. [Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park Norwich NR4 7TJ UK; Cramer, Stephen P. [Department of Chemistry, University of California, Davis CA 95616 USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 USA

    2016-10-25

    The reaction of protein-bound iron–sulfur (Fe-S) clusters with nitric oxide (NO) plays key roles in NO-mediated toxicity and signaling. Elucidation of the mechanism of the reaction of NO with DNA regulatory proteins that contain Fe-S clusters has been hampered by a lack of information about the nature of the iron-nitrosyl products formed. Herein, we report nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT) calculations that identify NO reaction products in WhiD and NsrR, regulatory proteins that use a [4Fe-4S] cluster to sense NO. This work reveals that nitrosylation yields multiple products structurally related to Roussin's Red Ester (RRE, [Fe2(NO)4(Cys)2]) and Roussin's Black Salt (RBS, [Fe4(NO)7S3]. In the latter case, the absence of 32S/34S shifts in the Fe-S region of the NRVS spectra suggest that a new species, Roussin's Black Ester (RBE), may be formed, in which one or more of the sulfide ligands is replaced by Cys thiolates.

  2. Nitrosyl complexes of technetium; Nitrosylkomplexe des Technetiums

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, Janine

    2016-09-22

    The presented thesis describes syntheses and characterization of novel technetium nitrosyl compounds with various ligand systems. The main focus is the synthesis of low-valent technetium nitrosyl complexes with cyclopentadienyl ligands. [German] Gegenstand der vorliegenden Arbeit ist die Synthese und Charakterisierung neuer Technetiumnitrosylverbindungen mit unterschiedlichen Ligandensystemen. Hauptaugenmerk wurde dabei auf die Darstellung niedervalenter Tc(NO)-Verbindungen mit Cyclopentadienyl-Liganden gelegt.

  3. Synthesis and characterisation of mono-nitrosyl complexes of ruthenium: reactivity of the coordinated nitrosyl

    International Nuclear Information System (INIS)

    Sueur, Stephane

    1977-01-01

    Within the frame of physical-chemical researches on radioactive effluents, their processing and their evolution, and within the perspective of a possible application to the fixing of radioactive ruthenium, this research thesis reports the study of reactions of barbituric acid with nitro-complexes of ruthenium-nitrosyl. First, the synthesis and the complete study of ketoxime complexes of ruthenium II have been performed. A radio-crystallographic study of HRu(H 2 vi) 3 ,4H 2 O allows the crystallisation of this compound and the molecular structure of Ru(H 2 vi) 3 - to be analysed. Nuclear magnetic resonance has been used to study this ion: the 'cis' structure noticed in solid phase remains present in solution. Spectroscopic studies (IR and FIR) have also been performed to further study the structure and of these tris-chelates. Their stoichiometry and titration have also been studied. The same techniques have then been applied to nitrosyl complexes for their synthesis, characterisation and structural study, and finally to the study of reactions of K 2 RuNOCl 5 and Na 2 RuNo(NO 2 ) 4 OH with barbituric acid

  4. Ruthenium nitrosyl complexes in radioactive waste solutions in reprocessing plants. Pt. 3

    International Nuclear Information System (INIS)

    Blasius, E.; Mueller, K.

    1984-01-01

    With capillary isotachophoresis and free-flow isotachophoresis it is possible to separate and isolate preparatively the mononuclear cationic ruthenium nitrosyl nitrato complexes. The behaviour of these complexes during storage, concentration and calcination is studied: The conversion of six ruthenium nitrosyl nitrato complexes as a function of time is studied at -36 0 C, 0 0 C, +3 0 C and 100 0 C. The percentage of ruthenium nitrosyl complexes with NO 3 - as ligand increased markedly during concentration experiments. Above 250 0 C NOsub(x) is liberated and the colour of the residue changes from brown to brownish-grey. At 400 0 C ruthenium complexes are no longer detected and the inner walls of the apparatus are covered with RuO 2 . (orig.)

  5. Reactions of Co(III)–Nitrosyl Complexes with Superoxide and Their Mechanistic Insights

    Science.gov (United States)

    Kumar, Pankaj; Lee, Yong-Min; Park, Young Jun; Siegler, Maxime A.; Karlin, Kenneth D.; Nam, Wonwoo

    2015-01-01

    New CoIII-nitrosyl complexes bearing N-tetramethylated cyclam (TMC) ligands, [(12-TMC)CoIII(NO)]2+ (1) and [(13-TMC)CoIII(NO)]2+ (2), were synthesized via [(TMC)CoII(CH3CN)]2+ plus NO(g) reactions. Spectroscopic and structural characterization shows that these compounds bind the nitrosyl moiety in a bent end-on fashion. The CoIII-nitrosyl complexes, (1) and (2), reacted with KO2/2.2.2-Cryptand and produced [(12-TMC)CoII(NO2)]+ (3) and [(13-TMC)CoII(NO2)]+ (4), respectively; these possess O,O’-chelated nitrito ligands. Mechanistic studies using 18O-labeled superoxide (18O2•−) demonstrate that one oxygen atom in the nitrito ligand derives from superoxide and dioxygen produced comes from the other superoxide oxygen atom. Evidence supporting the formation of a Co-peroxynitrite intermediate is also presented. PMID:25793706

  6. 3.3.1. Synthesis, Spectroscopy and Structural Analysis of Technetium and Rhenium Nitrosyl Complexes

    Directory of Open Access Journals (Sweden)

    Terrence\tNicholson*,\tEsther\tChunb, Ashfaq\tMahmood,\tPeter\tMueller,\tAlan\tDavisona\tand\tAlun\tG.\tJones

    2015-11-01

    Full Text Available Here we report an overview of our synthetic, spectroscopic and structural studies of technetium and rhenium nitrosyl complexes. We review the results from various notes and short papers reported over the past 15 years and discuss their significance in terms of radiopharmaceutical design.A single new complex is reported, the ReI-NO complex [ReICl2(NO(py-N(Et-py], in which the tridentate ligand di-(2-picolyl(N-ethylamine, (py-N(Et-py, is coordinated in a meridional manner. This complex was synthesized from the reaction of the ReI-nitrosyl complex ReCl2(NO(NCMe3] and the neutral tri-amine ligand py-N(Et-py in methylene chloride under argon. The bright red species was isolated chromatographically and recrystallized from CH2Cl2/MeOH under diethylether.A review of literature values for nitrosyl complexes with various ligands bound to the coordination sitetrans- to the nitrosyl group shows only minor variations in the M-N-O bond angle.

  7. Distorted tetrahedral nickel-nitrosyl complexes: spectroscopic characterization and electronic structure.

    Science.gov (United States)

    Soma, Shoko; Van Stappen, Casey; Kiss, Mercedesz; Szilagyi, Robert K; Lehnert, Nicolai; Fujisawa, Kiyoshi

    2016-09-01

    The linear nickel-nitrosyl complex [Ni(NO)(L3)] supported by a highly hindered tridentate nitrogen-based ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3), was prepared by the reaction of the potassium salt of the ligand with the nickel-nitrosyl precursor [Ni(NO)(Br)(PPh 3 ) 2 ]. The obtained nitrosyl complexes as well as the corresponding chlorido complexes [Ni(NO)(Cl)(PPh 3 ) 2 ] and [Ni(Cl)(L3)] were characterized by X-ray crystallography and different spectroscopic methods including IR/far-IR, UV-Vis, NMR, and multi-edge X-ray absorption spectroscopy at the Ni K-, Ni L-, Cl K-, and P K-edges. For comparative electronic structure analysis we also performed DFT calculations to further elucidate the electronic structure of [Ni(NO)(L3)]. These results provide the nickel oxidation state and the character of the Ni-NO bond. The complex [Ni(NO)(L3)] is best described as [Ni (II) (NO (-) )(L3)], and the spectroscopic results indicate that the phosphane complexes have a similar [Ni (II) (NO (-) )(X)(PPh 3 ) 2 ] ground state.

  8. Biological properties of novel ruthenium- and osmium-nitrosyl complexes with azole heterocycles

    KAUST Repository

    Novak, Maria S.

    2016-03-09

    Since the discovery that nitric oxide (NO) is a physiologically relevant molecule, there has been great interest in the use of metal nitrosyl compounds as antitumor pharmaceuticals. Particularly interesting are those complexes which can deliver NO to biological targets. Ruthenium- and osmium-based compounds offer lower toxicity compared to other metals and show different mechanisms of action as well as different spectra of activity compared to platinum-based drugs. Novel ruthenium- and osmium-nitrosyl complexes with azole heterocycles were studied to elucidate their cytotoxicity and possible interactions with DNA. Apoptosis induction, changes of mitochondrial transmembrane potential and possible formation of reactive oxygen species were investigated as indicators of NO-mediated damage by flow cytometry. Results suggest that ruthenium- and osmium-nitrosyl complexes with the general formula (indazolium)[cis/trans-MCl4(NO)(1H-indazole)] have pronounced cytotoxic potency in cancer cell lines. Especially the more potent ruthenium complexes strongly induce apoptosis associated with depolarization of mitochondrial membranes, and elevated reactive oxygen species levels. Furthermore, a slight yet not unequivocal trend to accumulation of intracellular cyclic guanosine monophosphate attributable to NO-mediated effects was observed.

  9. Biological properties of novel ruthenium- and osmium-nitrosyl complexes with azole heterocycles.

    Science.gov (United States)

    Novak, Maria S; Büchel, Gabriel E; Keppler, Bernhard K; Jakupec, Michael A

    2016-06-01

    Since the discovery that nitric oxide (NO) is a physiologically relevant molecule, there has been great interest in the use of metal nitrosyl compounds as antitumor pharmaceuticals. Particularly interesting are those complexes which can deliver NO to biological targets. Ruthenium- and osmium-based compounds offer lower toxicity compared to other metals and show different mechanisms of action as well as different spectra of activity compared to platinum-based drugs. Novel ruthenium- and osmium-nitrosyl complexes with azole heterocycles were studied to elucidate their cytotoxicity and possible interactions with DNA. Apoptosis induction, changes of mitochondrial transmembrane potential and possible formation of reactive oxygen species were investigated as indicators of NO-mediated damage by flow cytometry. Results suggest that ruthenium- and osmium-nitrosyl complexes with the general formula (indazolium)[cis/trans-MCl4(NO)(1H-indazole)] have pronounced cytotoxic potency in cancer cell lines. Especially the more potent ruthenium complexes strongly induce apoptosis associated with depolarization of mitochondrial membranes, and elevated reactive oxygen species levels. Furthermore, a slight yet not unequivocal trend to accumulation of intracellular cyclic guanosine monophosphate attributable to NO-mediated effects was observed.

  10. Complex catalysis. 19. Synthesis of nitrosyl complexes of tungsten and their usefulness as precatalysts for olefin metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Seyferth, K.; Rosenthal, K.; Kuehn, G.; Taube, R. (Technische Hochschule fuer Chemie, Leuna-Merseburg (German Democratic Republic). Sektion Chemie)

    1984-06-01

    Nitrosylating reduction of WCl/sub 6/ with NO leads to WCl/sub 3/(NO)/sub 4/ that on addition of different donor ligands L yields complexes of the types WCl/sub 3/(NO)L/sub 2/ (L = OPPh/sub 3/, HMPT, pyridine) and WX/sub 2/(NO)/sub 2/L/sub 2/ (L = PPh/sub 3/, X = Cl; XL = acac) or mixtures of products (L = Dipy, RCN, Et/sub 4/NCl), respectively. Whereas by carbonylation of WCl/sub 3/(NO)(OPPh/sub 3/)/sub 2/ in the presence of EtAlCl/sub 2/ only chloro carbonyl tungsten complexes formed, the reaction of W(CO)/sub 6/ with NOAlCl/sub 4/ and subsequent addition of PPh/sub 3/ gives, in analogy to molybdenum, the nitrosyl carbonyl complexes W(NO)(CO)/sub 4/(AlCl/sub 4/) and WCl(NO)(CO)/sub 2/(PPh/sub 3/)/sub 2/. All the nitrosyl tungsten complexes in combination with EtAlCl/sub 2/ catalyze the metathesis of pent-2-ene, however, with a significantly lower activity than the corresponding nitrosyl molybdenum systems.

  11. Synthesis, characterization and reactivity of nitrite and nitrosyl derivates of phosphane complexes of tetraamminrethenium (II)

    International Nuclear Information System (INIS)

    Souza Santos, L. de.

    1988-01-01

    The substitution reaction: trans-[Ru(NH 3 ) 4 P(III) (H 2 O)] 2+ + NO - 2 K 1 K -1 trans-[Ru(NH 3 ) 4 P(III) (NO 2 ) + + H 2 O. The reaction product has been isolated as trans-[Ru(NH 3 ) 4 P(III) (NO 2 )] (PF 6 ) and characterized by using electronic and infrared spectroscopies and cyclic voltammetry, microanalysis and conductometry techniques. This nitrite complex can be converted into the nitrosyl complex in solution by adding H + , according to: trans-[Ru(NH 3 ) 4 P(III) (NO 2 )] + + 2H + →sup (K)1 trans-[Ru(NH 3 ) 4 P(III) (NO)] 3+ + H 2 O which can be converted back to the nitrite derivative by adding alkali: trans-[Ru(NH 3 ) 4 P(III) (NO)] 3+ + 2 OH - →sup (K)-1 trans-[Ru(NH 3 ) 4 P(III) (NO 2 )] + + H 2 O. The nitrosyl complexes have been synthesized by reaction of NO with trans-[Ru(NH 3 ) 4 P(III) ( 2 O)] 2+ or by reacting the nitrite derivative in acidic solutions, and characterized by eletronic and infrared spetroscopies, cyclic voltametry, microanalysis, eletron paramagnetic resonance (E.P.R.) and nuclear magnetic resonance (N.M.R.) techniques. E.P.R. and N.M.R. data suggest that these complexes are diamagnetic and better formulated as Ru(II)-NO + . (author) [pt

  12. Structure and Bonding in Heme-Nitrosyl Complexes and Implications for Biology

    Energy Technology Data Exchange (ETDEWEB)

    Lehnert, Nicolai; Scheidt, W. Robert; Wolf, Matthew W. [Michigan; (Notre)

    2016-09-13

    This review summarizes our current understanding of the geometric and electronic structures of ferrous and ferric heme–nitrosyls, which are of key importance for the biological functions and transformations of NO. In-depth correlations are made between these properties and the reactivities of these species. Here, a focus is put on the discoveries that have been made in the last 10 years, but previous findings are also included as necessary. Besides this, ferrous heme–nitroxyl complexes are also considered, which have become of increasing interest recently due to their roles as intermediates in NO and multiheme nitrite reductases, and because of the potential role of HNO as a signaling molecule in mammals. In recent years, computational methods have received more attention as a means of investigating enzyme reaction mechanisms, and some important findings from these theoretical studies are also highlighted in this chapter.

  13. Study of the formation of complexes of nitrosyl-rhutenium nitrates with thiourea

    International Nuclear Information System (INIS)

    Floh, B.

    1977-01-01

    A method for the treatment of spent uranium fuel is presented, based on the Purex process using thiourea to increase the ruthenium decontamination factor. Thiourea exhibits a strong tendency for the formation of coordination compounds in acidic media. This tendency serves as a basis to transform nitrosyl-ruthenium species into Ru/SC(NH)(NH 2 )/ 2+ and Ru/SC(NH)(NH 2 )/ 3 complexes which are unextractable by TBP-varsol. The best conditions for the ruthenium-thiourea complex formation were found to be: thiourea-ruthenium ratio (mass/mass) close to 42, at 75 0 C, 30 minutes reaction time and aging period of 60 minutes. The ruthenium decontamination factor for a single uranium extraction are ca. 80-100, not interfering with extraction of actinides. These values are rather high in comparison to those obtained using the conventional Purex process (e.g. F.D. sub(Ru)=10). For this reason, the method developed here is suitable for the treatment of spent uranium fuels. Thiourea (100 g/l) scrubbing experiments of ruthenium, partially co-extracted with actinides, confirmed the possibility of its removal from the extract. With this procedure a decontamination greater than 83,5% for ruthenium as fission product is obtained in two stages [pt

  14. Nitro/Nitrosyl-Ruthenium Complexes Are Potent and Selective Anti-Trypanosoma cruzi Agents Causing Autophagy and Necrotic Parasite Death

    Science.gov (United States)

    Bastos, Tanira M.; Barbosa, Marília I. F.; da Silva, Monize M.; da C. Júnior, José W.; Meira, Cássio S.; Guimaraes, Elisalva T.; Ellena, Javier; Moreira, Diogo R. M.; Batista, Alzir A.

    2014-01-01

    cis-[RuCl(NO2)(dppb)(5,5′-mebipy)] (complex 1), cis-[Ru(NO2)2(dppb)(5,5′-mebipy)] (complex 2), ct-[RuCl(NO)(dppb)(5,5′-mebipy)](PF6)2 (complex 3), and cc-[RuCl(NO)(dppb)(5,5′-mebipy)](PF6)2 (complex 4), where 5,5′-mebipy is 5,5′-dimethyl-2,2′-bipyridine and dppb is 1,4-bis(diphenylphosphino)butane, were synthesized and characterized. The structure of complex 2 was determined by X-ray crystallography. These complexes exhibited a higher anti-Trypanosoma cruzi activity than benznidazole, the current antiparasitic drug. Complex 3 was the most potent, displaying a 50% effective concentration (EC50) of 2.1 ± 0.6 μM against trypomastigotes and a 50% inhibitory concentration (IC50) of 1.3 ± 0.2 μM against amastigotes, while it displayed a 50% cytotoxic concentration (CC50) of 51.4 ± 0.2 μM in macrophages. It was observed that the nitrosyl complex 3, but not its analog lacking the nitrosyl group, releases nitric oxide into parasite cells. This release has a diminished effect on the trypanosomal protease cruzain but induces substantial parasite autophagy, which is followed by a series of irreversible morphological impairments to the parasites and finally results in cell death by necrosis. In infected mice, orally administered complex 3 (five times at a dose of 75 μmol/kg of body weight) reduced blood parasitemia and increased the survival rate of the mice. Combination index analysis of complex 3 indicated that its in vitro activity against trypomastigotes is synergic with benznidazole. In addition, drug combination enhanced efficacy in infected mice, suggesting that ruthenium-nitrosyl complexes are potential constituents for drug combinations. PMID:25092707

  15. Mono- and dinuclear non-heme iron–nitrosyl complexes: Models for key intermediates in bacterial nitric oxide reductases

    Energy Technology Data Exchange (ETDEWEB)

    Berto, Timothy C.; Speelman, Amy L.; Zheng, Sheng; Lehnert, Nicolai

    2013-01-01

    High-spin non-heme iron–nitrosyls are of direct interest to both the chemical and biological communities as these species exhibit interesting chemical properties and act as direct models for enzymatic intermediates. The electronic ground state of the ferrous NO complexes, {Fe–NO}7, is best described as high-spin FeIII antiferromagnetically coupled to NO-, generating the spectroscopically observed S = 3/2 ground state. These species have been identified as catalytically relevant to a variety of NO-reducing enzymes such as bacterial nitric oxide reductase (NorBC) and flavo(rubredoxin) nitric oxide reductase (FNOR). Recently, the corresponding one-electron reduced {Fe–NO}8 (nitroxyl) complexes have also been implicated as biologically significant species. In this review the available spectroscopic data for {Fe–NO}7 and {Fe–NO}8 mono- and dinuclear non-heme iron–nitrosyls are summarized, and the implications of these results with respect to the electronic structures and reactivities of these species, in particular towards NO reduction, are discussed.

  16. Striking Difference in Antiproliferative Activity of Ruthenium- and Osmium-Nitrosyl Complexes with Azole Heterocycles

    Science.gov (United States)

    2013-01-01

    Ruthenium nitrosyl complexes of the general formulas (cation)+[cis-RuCl4(NO)(Hazole)]−, where (cation)+ = (H2ind)+, Hazole = 1H-indazole (Hind) (1c), (cation)+ = (H2pz)+, Hazole = 1H-pyrazole (Hpz) (2c), (cation)+ = (H2bzim)+, Hazole = 1H-benzimidazole (Hbzim) (3c), (cation)+ = (H2im)+, Hazole = 1H-imidazole (Him) (4c) and (cation)+[trans-RuCl4(NO)(Hazole)]−, where (cation)+ = (H2ind)+, Hazole = 1H-indazole (1t), (cation)+ = (H2pz)+, Hazole = 1H-pyrazole (2t), as well as osmium analogues of the general formulas (cation)+[cis-OsCl4(NO)(Hazole)]−, where (cation)+ = (n-Bu4N)+, Hazole =1H-indazole (5c), 1H-pyrazole (6c), 1H-benzimidazole (7c), 1H-imidazole (8c), (cation)+ = Na+; Hazole =1H-indazole (9c), 1H-benzimidazole (10c), (cation)+ = (H2ind)+, Hazole = 1H-indazole (11c), (cation)+ = H2pz+, Hazole = 1H-pyrazole (12c), (cation)+ = (H2im)+, Hazole = 1H-imidazole (13c), and (cation)+[trans-OsCl4(NO)(Hazole)]−, where (cation)+ = n-Bu4N+, Hazole = 1H-indazole (5t), 1H-pyrazole (6t), (cation)+ = Na+, Hazole = 1H-indazole (9t), (cation)+ = (H2ind)+, Hazole = 1H-indazole (11t), (cation)+ = (H2pz)+, Hazole = 1H-pyrazole (12t), have been synthesized. The compounds have been comprehensively characterized by elemental analysis, ESI mass spectrometry, spectroscopic techniques (IR, UV–vis, 1D and 2D NMR) and X-ray crystallography (1c·CHCl3, 1t·CHCl3, 2t, 3c, 6c, 6t, 8c). The antiproliferative activity of water-soluble compounds (1c, 1t, 3c, 4c and 9c, 9t, 10c, 11c, 11t, 12c, 12t, 13c) in the human cancer cell lines A549 (nonsmall cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon adenocarcinoma) has been assayed. The effects of metal (Ru vs Os), cis/trans isomerism, and azole heterocycle identity on cytotoxic potency and cell line selectivity have been elucidated. Ruthenium complexes (1c, 1t, 3c, and 4c) yielded IC50 values in the low micromolar concentration range. In contrast to most pairs of analogous ruthenium and osmium complexes known, they turned

  17. New ruthenium nitrosyl complexes with tris(1-pyrazolyl)methane (tpm) and 2,2'-bipyridine (bpy) coligands. Structure, spectroscopy, and electrophilic and nucleophilic reactivities of bound nitrosyl.

    Science.gov (United States)

    Videla, Mariela; Jacinto, Julian S; Baggio, Ricardo; Garland, María T; Singh, Priti; Kaim, Wolfgang; Slep, Leonardo D; Olabe, José A

    2006-10-16

    The new compound [Ru(bpy)(tpm)NO](ClO4)3 [tpm = tris(1-pyrazolyl)methane; bpy = 2,2'-bipyridine] has been prepared in a stepwise procedure that involves the conversion of [Ru(bpy)(tpm)Cl]+ into the aqua and nitro intermediates, followed by acidification. The diamagnetic complex crystallizes to exhibit distorted octahedral geometry around the metal, with the Ru-N(O) bond length 1.774(12) A and the RuNO angle 179.1(12) degrees , typical for a {RuNO}6 description. The [Ru(bpy)(tpm)NO]3+ ion (I) has been characterized by 1H NMR and IR spectroscopies (nu(NO) = 1959 cm(-1)) and through density functional theory calculations. Intense electronic transitions in the 300-350-nm region are assigned through time-dependent (TD)DFT as intraligand pi --> pi for bpy and tpm. The dpi --> pi(bpy) metal-to-ligand charge-transfer transitions appear at higher energies. Aqueous cyclic voltammetric studies show a reversible wave at 0.31 V (vs Ag/AgCl, 3 M Cl-), which shifts to 0.60 V in MeCN, along with the onset of a wave of an irreversible process at -0.2 V. The waves are assigned to the one- and two-electron reductions centered at the NO ligand, leading to species with {RuNO}(7) and {RuNO}(8) configurations, respectively. Controlled potential reduction of I in MeCN led to the [Ru(bpy)(tpm)NO]2+ ion (II), revealing a significant downward shift of nu(NO) to 1660 cm(-1) as well as changes in the electronic absorption bands. II was also characterized by electron paramagnetic resonance, showing an anisotropic signal at 110 K that arises from an S = 1/2 electronic ground state; the g-matrix components and hyperfine coupling tensor resemble the behavior of related {RuNO}7 complexes. Both I and II were characterized through their main reactivity modes, electrophilic and nucleophilic, respectively. The addition of OH- into I generated the nitro complex, with k(OH) = 3.05 x 10(6) M(-1) s(-1) (25 degrees C). This value is among the highest obtained for related nitrosyl complexes and correlates

  18. Chemistry of Iron N -heterocyclic carbene complexes: Syntheses, structures, reactivities, and catalytic applications

    KAUST Repository

    Riener, Korbinian

    2014-05-28

    Iron is the most abundant transition metal in Earth\\'s crust. It is relatively inexpensive, not very toxic, and environmentally benign. Undoubtedly, due to the involvement in a multitude of biological processes, which heavily rely on the rich functionalities of iron-containing enzymes, iron is one of the most important elements in nature. Additionally, three-coordinate iron complexes have been reported during the past several years. In this review, the mentioned iron NHC complexes are categorized by their main structure and reactivity attributes. Thus, monocarbene and bis-monocarbene complexes are presented first. This class is subdivided into carbonyl, nitrosyl, and halide compounds followed by a brief section on other, more unconventional iron NHC motifs. Subsequently, donor-substituted complexes bearing bi-, tri-, tetra-, or even pentadentate ligands and further pincer as well as scorpionato motifs are described.

  19. Activation of Small Molecules at Iron Complexes in Varying Trigonal Ligand Environments

    OpenAIRE

    Hohenberger, Johannes

    2017-01-01

    Iron nitrido and nitrosyl/nitroxyl model complexes have been of great interest owing to their role as reactive intermediates and transfer reagents and their role in biochemical reactions involving nitrogen and NO. The stable iron(IV) nitrido complex [(TIMENMes)FeIV(N)]BPh4 (TIMENMes = tris-[2 (3-mesitylimidazol-2 ylidene)¬ethyl]¬amine), synthesized by Meyer and co-workers in 2008, proved to be uncreative towards electrophiles or nucleophiles and thus, the increase of its reactivity was tested...

  20. Characterization of Water Coordination to Ferrous Nitrosyl Complexes with fac-N2O, cis-N2O2, and N2O3 Donor Ligands.

    Science.gov (United States)

    McCracken, John; Cappillino, Patrick J; McNally, Joshua S; Krzyaniak, Matthew D; Howart, Michael; Tarves, Paul C; Caradonna, John P

    2015-07-06

    Electron paramagnetic resonance (EPR) experiments were done on a series of S = (3)/2 ferrous nitrosyl model complexes prepared with chelating ligands that mimic the 2-His-1-carboxylate facial triad iron binding motif of the mononuclear nonheme iron oxidases. These complexes formed a comparative family, {FeNO}(7)(N2Ox)(H2O)3-x with x = 1-3, where the labile coordination sites for the binding of NO and solvent water were fac for x = 1 and cis for x = 2. The continuous-wave EPR spectra of these three complexes were typical of high-spin S = (3)/2 transition-metal ions with resonances near g = 4 and 2. Orientation-selective hyperfine sublevel correlation (HYSCORE) spectra revealed cross peaks arising from the protons of coordinated water in a clean spectral window from g = 3.0 to 2.3. These cross peaks were absent for the {FeNO}(7)(N2O3) complex. HYSCORE spectra were analyzed using a straightforward model for defining the spin Hamiltonian parameters of bound water and showed that, for the {FeNO}(7)(N2O2)(H2O) complex, a single water conformer with an isotropic hyperfine coupling, Aiso = 0.0 ± 0.3 MHz, and a dipolar coupling of T = 4.8 ± 0.2 MHz could account for the data. For the {FeNO}(7)(N2O)(H2O)2 complex, the HYSCORE cross peaks assigned to coordinated water showed more frequency dispersion and were analyzed with discrete orientations and hyperfine couplings for the two water molecules that accounted for the observed orientation-selective contour shapes. The use of three-pulse electron spin echo envelope modulation (ESEEM) data to quantify the number of water ligands coordinated to the {FeNO}(7) centers was explored. For this aspect of the study, HYSCORE spectra were important for defining a spectral window where empirical integration of ESEEM spectra would be the most accurate.

  1. A peroxynitrite complex of copper: formation from a copper-nitrosyl complex, transformation to nitrite and exogenous phenol oxidative coupling or nitration.

    Science.gov (United States)

    Park, Ga Young; Deepalatha, Subramanian; Puiu, Simona C; Lee, Dong-Heon; Mondal, Biplab; Narducci Sarjeant, Amy A; del Rio, Diego; Pau, Monita Y M; Solomon, Edward I; Karlin, Kenneth D

    2009-11-01

    Reaction of nitrogen monoxide with a copper(I) complex possessing a tridentate alkylamine ligand gives a Cu(I)-(*NO) adduct, which when exposed to dioxygen generates a peroxynitrite (O=NOO(-))-Cu(II) species. This undergoes thermal transformation to produce a copper(II) nitrito (NO(2) (-)) complex and 0.5 mol equiv O(2). In the presence of a substituted phenol, the peroxynitrite complex effects oxidative coupling, whereas addition of chloride ion to dissociate the peroxynitrite moiety instead leads to phenol ortho nitration. Discussions include the structures (including electronic description) of the copper-nitrosyl and copper-peroxynitrite complexes and the formation of the latter, based on density functional theory calculations and accompanying spectroscopic data.

  2. A peroxynitrite complex of copper: formation from a copper–nitrosyl complex, transformation to nitrite and exogenous phenol oxidative coupling or nitration

    Science.gov (United States)

    Park, Ga Young; Deepalatha, Subramanian; Puiu, Simona C.; Lee, Dong-Heon; Mondal, Biplab; Sarjeant, Amy A. Narducci; del Rio, Diego; Pau, Monita Y. M.; Solomon, Edward I.; Karlin, Kenneth D.

    2010-01-01

    Reaction of nitrogen monoxide with a copper(I) complex possessing a tridentate alkylamine ligand gives a Cu(I)–(·NO) adduct, which when exposed to dioxygen generates a peroxynitrite (O=NOO−)–Cu(II) species. This undergoes thermal transformation to produce a copper(II) nitrito (NO2−) complex and 0.5 mol equiv O2. In the presence of a substituted phenol, the peroxynitrite complex effects oxidative coupling, whereas addition of chloride ion to dissociate the peroxynitrite moiety instead leads to phenol ortho nitration. Discussions include the structures (including electronic description) of the copper–nitrosyl and copper–peroxynitrite complexes and the formation of the latter, based on density functional theory calculations and accompanying spectroscopic data. PMID:19662443

  3. Redox Properties of Ruthenium Nitrosyl Porphyrin Complexes with Different Axial Ligation: Structural, Spectroelectrochemical (IR, UV-VIS, EPR) and Theoretical Studies

    Czech Academy of Sciences Publication Activity Database

    Singh, P.; Das, A. K.; Sarkar, B.; Niemeyer, M.; Roncaroli, F.; Olabe, J. A.; Fiedler, Jan; Záliš, Stanislav; Kaim, W.

    2008-01-01

    Roč. 47, č. 16 (2008), s. 7106-7113 ISSN 0020-1669 R&D Projects: GA AV ČR KAN100400702; GA MŠk OC 139; GA MŠk 1P05OC068 Institutional research plan: CEZ:AV0Z40400503 Keywords : ruthenium nitrosyl porphyrin complexes * tetraphenylporphyrin dianiom * EPR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.147, year: 2008

  4. Electronic and stereochemical characterizations of the photoinduced intermediates of nitrosyl complexes of metal (S = 5/2)-substituted hemoproteins trapped at low temperature.

    Science.gov (United States)

    Hori, H; Ikeda-Saito, M; Lang, G; Yonetani, T

    1990-09-05

    Low temperature photolysis of nitric oxide from the nitrosyl complexes of ferric myoglobin (NO-Fe(III)Mb) and manganese(II)-porphyrin-substituted myoglobin (NO-Mn(II)Mb) was examined by electron paramagnetic resonance (EPR) spectroscopy in order to elucidate the electronic and structural natures of the photoinduced intermediates of these hemoprotein-ligand complexes trapped at low temperature. The photoproduct of NO-Fe(III)Mb at 5 K exhibited entirely new X-band EPR absorptions in the magnetic field strength from 0 to 0.4 tesla. The widespread absorption together with distinct, sharp zero-field absorption was consistently observed in the photoproduct of the isoelectronic NO-Mn(II)Mb. These novel ERP signals indicate a spin-coupled pair with an effective spin of S = 2 between the high spin metal center (S = 5/2) and the photodissociated NO (S = 1/2) trapped adjacent to the metal center. On the other hand, the photolyzed form of nitrosyl complexes of Fe(III)- and Mn(II)-Glycera hemoglobins, in which the distal histidine of Mb is replaced by a leucyl residue, exhibited somewhat broader EPR absorptions similar to those of the corresponding native Fe(III)- or unliganded Mn(II)-Glycera hemoglobins, respectively, indicating that the photodissociated NO molecule moved farther away from the metal center in the heme pocket. These observations show the importance of the interaction of the distal residue with the ligand in determining the nature of the photolyzed states.

  5. DFT Mechanistic Study of the Selective Terminal C-H Activation of n-Pentane with a Tungsten Allyl Nitrosyl Complex

    KAUST Repository

    Lee, Richmond

    2017-01-17

    Mechanistic insights into the selective C-H terminal activation of n-pentane with tungsten allyl nitrosyl complex reported by Legzdins were gained by employing density functional theory with B3LYP hybrid functional. Using Bader’s atom in molecules (AIM) analysis on the elementary steps of the hydrogen transfer process, TS1 and TS2, it was observed that the calculated H-transfer models were closely similar to Hall’s metal-assisted σ-bond metathesis through bond critical point (BCP) comparisons. One distinguishable feature was the fact that the formal oxidation state of the W changed in the concerted H-transfer process. To better differentiate, we term these processes as ‘Formal Reductive Hydrogen Transfer’ (FRHT) for TS1 and ‘Formal Oxidative Hydrogen Transfer’ (FOHT) for TS2.

  6. DFT mechanistic study of the selective terminal C–H activation of n-pentane with a tungsten allyl nitrosyl complex

    Directory of Open Access Journals (Sweden)

    Richmond Lee

    2017-07-01

    Full Text Available Mechanistic insights into the selective C–H terminal activation of n-pentane with tungsten allyl nitrosyl complex reported by Legzdins were gained by employing density functional theory with B3LYP hybrid functional. Using Bader’s atom in molecules (AIM analysis on the elementary steps of the hydrogen transfer process, TS1 and TS2, it was observed that the calculated H-transfer models were closely similar to Hall’s metal-assisted σ-bond metathesis through bond critical point (BCP comparisons. One distinguishable feature was the fact that the formal oxidation state of the W changed in the concerted H-transfer process. To better differentiate, we term these processes as ‘Formal Reductive Hydrogen Transfer’ (FRHT for TS1 and ‘Formal Oxidative Hydrogen Transfer’ (FOHT for TS2.

  7. Moessbauer study of iron-sugar complexes

    International Nuclear Information System (INIS)

    Tonkovic, M.; Music, S.; Hadzija, O.; Nagy-Czako, I.; Vertes, A.

    1982-01-01

    Ferric-fructose complex has been prepared using FeCl 3 and Fe(NO 3 ) 3 solutions. Molecular weight determination and Moessbauer spectroscopic measurements proved that the ferric-fructose complex is polymeric in solid state and also in aqueous solution. The synthesis of a new iron-sorbose complex has been performed. Its Moessbauer spectra indicate a structure similar to that of the iron-fructose complex. (author)

  8. Development of nitrosyl ruthenium complex-loaded lipid carriers for topical administration: improvement in skin stability and in nitric oxide release by visible light irradiation.

    Science.gov (United States)

    Marquele-Oliveira, Franciane; Santana, Danielle Cristine de Almeida; Taveira, Stephânia Fleury; Vermeulen, Deise Mirella; de Oliveira, Anderson Rodrigo Moraes; da Silva, Roberto Santana; Lopez, Renata Fonseca Vianna

    2010-12-01

    The prominent nitric oxide (NO) donor [Ru(terpy)(bdqi)NO](PF(6))(3) has been synthesized and evaluated with respect to noteworthy biological effects due to its NO photorelease, including vascular relaxation and melanoma cell culture toxicity. The potential for delivering NO in therapeutic quantities is tenable since the nitrosyl ruthenium complex (NRC) must first reach the "target tissue" and then release the NO upon stimulus. In this context, NRC-loaded lipid carriers were developed and characterized to further explore its topical administration for applications such as skin cancer treatment. NRC-loaded solid lipid nanoparticles (SLN) and nanostructured lipid carriers were prepared via the microemulsification method, with average diameters of 275+/-15 nm and 211+/-31 nm and zeta potentials of -40.7+/-10.4 mV and -50.0+/-7.5 mV, respectively. In vitro kinetic studies of NRC release from nanoparticles showed sustained release of NRC from the lipid carriers and illustrated the influence of the release medium and the lyophilization process. Stability studies showed that NO is released from NRC as a function of temperature and time and due to skin contact. The encapsulation of NRC in SLN followed by its lyophilization, significantly improved the complex stability. Furthermore, of particular interest was the fact that in the NO photorelease study, the NO release from the NRC-loaded SLN was approximately twice that of just NRC in solution. NRC-loaded SLN performs well enough at releasing and protecting NO degradation in vitro that it is a promising carrier for topical delivery of NO. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  9. Analytical gradients of complete active space self-consistent field energies using Cholesky decomposition: geometry optimization and spin-state energetics of a ruthenium nitrosyl complex.

    Science.gov (United States)

    Delcey, Mickaël G; Freitag, Leon; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland; González, Leticia

    2014-05-07

    We present a formulation of analytical energy gradients at the complete active space self-consistent field (CASSCF) level of theory employing density fitting (DF) techniques to enable efficient geometry optimizations of large systems. As an example, the ground and lowest triplet state geometries of a ruthenium nitrosyl complex are computed at the DF-CASSCF level of theory and compared with structures obtained from density functional theory (DFT) using the B3LYP, BP86, and M06L functionals. The average deviation of all bond lengths compared to the crystal structure is 0.042 Å at the DF-CASSCF level of theory, which is slightly larger but still comparable with the deviations obtained by the tested DFT functionals, e.g., 0.032 Å with M06L. Specifically, the root-mean-square deviation between the DF-CASSCF and best DFT coordinates, delivered by BP86, is only 0.08 Å for S0 and 0.11 Å for T1, indicating that the geometries are very similar. While keeping the mean energy gradient errors below 0.25%, the DF technique results in a 13-fold speedup compared to the conventional CASSCF geometry optimization algorithm. Additionally, we assess the singlet-triplet energy vertical and adiabatic differences with multiconfigurational second-order perturbation theory (CASPT2) using the DF-CASSCF and DFT optimized geometries. It is found that the vertical CASPT2 energies are relatively similar regardless of the geometry employed whereas the adiabatic singlet-triplet gaps are more sensitive to the chosen triplet geometry.

  10. Iron complexes of pharmaceutical interest: Antianemics

    Directory of Open Access Journals (Sweden)

    Cakić Milorad D.

    2003-01-01

    Full Text Available Preparations based on different compounds of bi- and trivalent iron are curently used for the prevention and therapy of sideropenic anemia in human and veterinary medicine. The application of preparations based on dextran started about 1950. Up to now, synthesis and production of preparations were performed with the purpose of improving pharmacological performance by using dextran oligosaccharides with different weight - average molar masses and their oxidized and hydrogenated derivatives. Synthesis of polynuclear iron(lll complexs with other oligosaccharides (inulin and pullulan and their derivatives was developed, with potential or valid pharmacological activity for sideropenic anemia treatment.A Review of iron(lll complexes with different oligosaccharides, their physico-chemical characterization pharmaco-biological performance, global structure, further research and possible applications of then complexes, are presented in this paper.

  11. Mechanism elucidation of the cis-trans isomerization of an azole ruthenium-nitrosyl complex and its osmium counterpart.

    Science.gov (United States)

    Gavriluta, Anatolie; Büchel, Gabriel E; Freitag, Leon; Novitchi, Ghenadie; Tommasino, Jean Bernard; Jeanneau, Erwann; Kuhn, Paul-Steffen; González, Leticia; Arion, Vladimir B; Luneau, Dominique

    2013-06-03

    Synthesis and X-ray diffraction structures of cis and trans isomers of ruthenium and osmium metal complexes of general formulas (nBu4N)[cis-MCl4(NO)(Hind)], where M = Ru (1) and Os (3), and (nBu4N)[trans-MCl4(NO)(Hind)], where M = Ru (2) and Os (4) and Hind = 1H-indazole are reported. Interconversion between cis and trans isomers at high temperatures (80-130 °C) has been observed and studied by NMR spectroscopy. Kinetic data indicate that isomerizations correspond to reversible first order reactions. The rates of isomerization reactions even at 110 °C are very low with rate constants of 10(-5) s(-1) and 10(-6) s(-1) for ruthenium and osmium complexes, respectively, and the estimated rate constants of isomerization at room temperature are of ca. 10(-10) s(-1). The activation parameters, which have been obtained from fitting the reaction rates at different temperatures to the Eyring equation for ruthenium [ΔH(cis-trans)‡ = 122.8 ± 1.3; ΔH(trans-cis)‡ = 138.8 ± 1.0 kJ/mol; ΔS(cis-trans)‡ = -18.7 ± 3.6; ΔS(trans-cis)‡ = 31.8 ± 2.7 J/(mol·K)] and osmium [ΔH(cis-trans)‡ = 200.7 ± 0.7; ΔH(trans-cis)‡ = 168.2 ± 0.6 kJ/mol; ΔS(cis-trans)‡ = 142.7 ± 8.9; ΔS(trans-cis)‡ = 85.9 ± 3.9 J/(mol·K)] reflect the inertness of these systems. The entropy of activation for the osmium complexes is highly positive and suggests the dissociative mechanism of isomerization. In the case of ruthenium, the activation entropy for the cis to trans isomerization is negative [-18.6 J/(mol·K)], while being positive [31.0 J/(mol·K)] for the trans to cis conversion. The thermodynamic parameters for cis to trans isomerization of [RuCl4(NO)(Hind)]-, viz. ΔH° = 13.5 ± 1.5 kJ/mol and ΔS° = -5.2 ± 3.4 J/(mol·K) indicate the low difference between the energies of cis and trans isomers. The theoretical calculation has been carried out on isomerization of ruthenium complexes with DFT methods. The dissociative, associative, and intramolecular twist isomerization

  12. Mechanism Elucidation of the cis–trans Isomerization of an Azole Ruthenium–Nitrosyl Complex and Its Osmium Counterpart

    Science.gov (United States)

    2013-01-01

    Synthesis and X-ray diffraction structures of cis and trans isomers of ruthenium and osmium metal complexes of general formulas (nBu4N)[cis-MCl4(NO)(Hind)], where M = Ru (1) and Os (3), and (nBu4N)[trans-MCl4(NO)(Hind)], where M = Ru (2) and Os (4) and Hind = 1H-indazole are reported. Interconversion between cis and trans isomers at high temperatures (80–130 °C) has been observed and studied by NMR spectroscopy. Kinetic data indicate that isomerizations correspond to reversible first order reactions. The rates of isomerization reactions even at 110 °C are very low with rate constants of 10–5 s–1 and 10–6 s–1 for ruthenium and osmium complexes, respectively, and the estimated rate constants of isomerization at room temperature are of ca. 10–10 s–1. The activation parameters, which have been obtained from fitting the reaction rates at different temperatures to the Eyring equation for ruthenium [ΔHcis-trans‡= 122.8 ± 1.3; ΔHtrans-cis‡= 138.8 ± 1.0 kJ/mol; ΔScis-trans‡= −18.7 ± 3.6; ΔStrans-cis‡= 31.8 ± 2.7 J/(mol·K)] and osmium [ΔHcis-trans‡= 200.7 ± 0.7; ΔHtrans-cis‡= 168.2 ± 0.6 kJ/mol; ΔScis-trans‡= 142.7 ± 8.9; ΔStrans-cis‡= 85.9 ± 3.9 J/(mol·K)] reflect the inertness of these systems. The entropy of activation for the osmium complexes is highly positive and suggests the dissociative mechanism of isomerization. In the case of ruthenium, the activation entropy for the cis to trans isomerization is negative [−18.6 J/(mol·K)], while being positive [31.0 J/(mol·K)] for the trans to cis conversion. The thermodynamic parameters for cis to trans isomerization of [RuCl4(NO)(Hind)]−, viz. ΔH° = 13.5 ± 1.5 kJ/mol and ΔS° = −5.2 ± 3.4 J/(mol·K) indicate the low difference between the energies of cis and trans isomers. The theoretical calculation has been carried out on isomerization of ruthenium complexes with DFT methods. The dissociative, associative, and intramolecular twist isomerization mechanisms have

  13. 2, 4-Diamino-6- hydroxy pyrimidine inhibits NSAIDs induced nitrosyl-complex EPR signals and ulcer in rat jejunum

    Directory of Open Access Journals (Sweden)

    Bjarnason I

    2002-04-01

    Full Text Available Abstract Background It has been suggested that one aspect of non-steroidal anti-inflammatory drugs induced intestinal damage is due to either uncoupling of mitochondrial oxidative phosphorylation or inhibition of electron transport. We investigated the latter possibility using electron paramagnetic resonance spectroscopy. Results Electron paramagnetic studies of NSAIDS on sub-mitochondrial particles revealed that indomethacin, but not with nabumetone, bound to a site near to Complex I and ubiquinone to generate a radical species. Normal rats exhibited prominent [3Fe-4S]ox signals (g ~ 2.01 at 20 K. One hour after indomethacin there was a prominent, intense and broad absorption pattern at (g ~2.07 suggesting, appearance of radical species overlapping [3Fe-4S]ox and was unaffected by pretreatment with 2,4 diamino -6-hydroxy pyrimidine. At 24 hrs, when macroscopic ulcers were seen, there was a new signal due to a nitric oxide radical (NO•. In contrast, nabumetone and 2,4 diamino-6-hydroxy pyrimidine pre-treated animals receiving indomethacin exhibited electron paramagnetic resonance spectra identical to those of controls at 24 hrs and neither was associated with small intestinal ulcers. Indomethacin and 2,4 diamino hydroxy pyrimidine pre-treated rats, but not nabumetone, had increased intestinal permeability. Conclusion The results suggest that the in vivo effects of indomethacin modulate the mitochondrial respiratory chain directly at 1 h and 24 h through formation of nitric oxide. NO• appears to play an important role in the late pathogenic stages of NSAID enteropathy and may be the site for targeted treatment to reduce their toxicity.

  14. CALCIUM CARBONATE REDUCES IRON ABSORPTION FROM IRON SULFATE, BUT NOT WHEN IRON IS PRESENTED AS AN ORGANIC COMPLEX

    Directory of Open Access Journals (Sweden)

    E. C. CONCEIÇÃO

    2008-09-01

    Full Text Available

    Experimental and epidemiological evidences have demonstrated that calcium inhibits iron absorption; calcium carbonate being one of the most effective calcium sources to reduce iron absorption from dietary origin or from iron sulfate. In the present work, the short-term effect of calcium from calcium carbonate on iron absorption was studied in rats, using different iron compounds (monosodium ferric EDTA, iron-bys-glicine, iron peptide complex with iron sulfate as a control. Eighty (80 animals were divided into groups of 10 animals each with homogeneous weight. After 18h fast, the animals received by gavage 5 mL of a dispersion containing one of the iron compounds (1mg Fe/kg body weight, concomitantly or not with calcium carbonate at a molar ratio of 150:1 (Ca/Fe. Two hours after the administration, the animals were sacrificed and blood was collected for serum iron determination (iron transfer rate from intestinal lumen to blood compartment. Additionally, the intestines were collected for soluble iron determination (available iron. The results demonstrated that calcium ion from calcium carbonate inhibits the iron absorption from iron sulfate, but not from organic iron (di- or trivalent complexes.

  15. Reversible dissociation and ligand-glutathione exchange reaction in binuclear cationic tetranitrosyl iron complex with penicillamine.

    Science.gov (United States)

    Syrtsova, Lidia; Sanina, Natalia; Lyssenko, Konstantin; Kabachkov, Evgeniy; Psikha, Boris; Shkondina, Natal'ja; Pokidova, Olesia; Kotelnikov, Alexander; Aldoshin, Sergey

    2014-01-01

    This paper describes a comparative study of the decomposition of two nitrosyl iron complexes (NICs) with penicillamine thiolic ligands [Fe2(SC5H11NO2)2(NO)4]SO4 ·5H2O (I) and glutathione- (GSH-) ligands [Fe2(SC10H17N3O6)2(NO)4]SO4 ·2H2O (II), which spontaneously evolve to NO in aqueous medium. NO formation was measured by a sensor electrode and by spectrophotometric methods by measuring the formation of a hemoglobin- (Hb-) NO complex. The NO evolution reaction rate from (I)  k 1 = (4.6 ± 0.1)·10(-3) s(-1) and the elimination rate constant of the penicillamine ligand k 2 = (1.8 ± 0.2)·10(-3) s(-1) at 25°C in 0.05 M phosphate buffer,  pH 7.0, was calculated using kinetic modeling based on the experimental data. Both reactions are reversible. Spectrophotometry and mass-spectrometry methods have firmly shown that the penicillamine ligand is exchanged for GS(-) during decomposition of 1.5·10(-4) M (I) in the presence of 10(-3) M GSH, with 76% yield in 24 h. As has been established, such behaviour is caused by the resistance of (II) to decomposition due to the higher affinity of iron to GSH in the complex. The discovered reaction may impede S-glutathionylation of the essential enzyme systems in the presence of (I) and is important for metabolism of NIC, connected with its antitumor activity.

  16. Geology of the Biwabik Iron Formation and Duluth Complex.

    Science.gov (United States)

    Jirsa, Mark A; Miller, James D; Morey, G B

    2008-10-01

    The Biwabik Iron Formation is a approximately 1.9 billion year-old sequence of iron-rich sedimentary rocks that was metamorphosed at its eastern-most extent by approximately 1.1 billion year-old intrusions of the Duluth Complex. The metamorphic recrystallization of iron-formation locally produced iron-rich amphiboles and other fibrous iron-silicate minerals. The presence of these minerals in iron-formation along the eastern part of what is known as the Mesabi Iron Range, and their potential liberation by iron mining has raised environmental health concerns. We describe here the geologic setting and mineralogic composition of the Biwabik Iron Formation in and adjacent to the contact metamorphic aureole of the Duluth Complex. The effects of metamorphism are most pronounced within a few kilometers of the contact, and decrease progressively away from it. The contact aureole has been divided into four metamorphic zones-each characterized by the composition and crystal structure of the metamorphic minerals it contains. The recrystallization of iron-formation to iron-rich amphibole minerals (grunerite and cummingtonite) and iron-pyroxene minerals (hedenbergite and ferrohypersthene) is best developed in zones that are most proximal to the Duluth Complex contact.

  17. Geology of the Biwabik Iron Formation and Duluth Complex

    Science.gov (United States)

    Jirsa, M.A.; Miller, J.D.; Morey, G.B.

    2008-01-01

    The Biwabik Iron Formation is a ???1.9 billion year-old sequence of iron-rich sedimentary rocks that was metamorphosed at its eastern-most extent by ???1.1 billion year-old intrusions of the Duluth Complex. The metamorphic recrystallization of iron-formation locally produced iron-rich amphiboles and other fibrous iron-silicate minerals. The presence of these minerals in iron-formation along the eastern part of what is known as the Mesabi Iron Range, and their potential liberation by iron mining has raised environmental health concerns. We describe here the geologic setting and mineralogic composition of the Biwabik Iron Formation in and adjacent to the contact metamorphic aureole of the Duluth Complex. The effects of metamorphism are most pronounced within a few kilometers of the contact, and decrease progressively away from it. The contact aureole has been divided into four metamorphic zones-each characterized by the composition and crystal structure of the metamorphic minerals it contains. The recrystallization of iron-formation to iron-rich amphibole minerals (grunerite and cummingtonite) and iron-pyroxene minerals (hedenbergite and ferrohypersthene) is best developed in zones that are most proximal to the Duluth Complex contact. ?? 2007 Elsevier Inc. All rights reserved.

  18. Complex Formation Between Iron(III) and Isonicotinohydroxamic ...

    African Journals Online (AJOL)

    acer

    ion complexes (Fernandes et al., 1997). Hydroxamic acids and other compounds containing the hydroxamate group are ubiquitous in nature and are intimately associated with iron transport in bacteria (Nwabueze 1997). Iron(III) complexes of naturally occurring hydroxamate acids called siderophores, are involved in the.

  19. Bioavailability of iron speciations and EDTA-iron complexes for ...

    African Journals Online (AJOL)

    Selin

    2012-01-19

    . The filters were kept in a 3 M HCl-bath for two days to remove iron, and then kept in 1 M trace metal free- HCl, prepared by isothermal distillation over a week with replacement of the HCl solution every day. At the end of the ...

  20. Physiological Levels of Nitric Oxide Diminish Mitochondrial Superoxide. Potential Role of Mitochondrial Dinitrosyl Iron Complexes and Nitrosothiols

    Directory of Open Access Journals (Sweden)

    Sergey I. Dikalov

    2017-11-01

    spectra of Fe(MGD2 supplemented mitochondrial lysates showed presence of both dinitrosyl iron complexes and nitrosothiols. We suggest that nitric oxide attenuates production of mitochondrial superoxide by post-translational modifications by nitrosylation of protein cysteine residues and formation of protein dinitrosyl iron complexes with thiol-containing ligands and, therefore, nitric oxide reduction in pathological conditions associated with endothelial dysfunction may increase mitochondrial oxidative stress.

  1. A fluorogenic probe for imaging protein S-nitrosylation in live cells.

    Science.gov (United States)

    Shao, Shiyi; Chen, Bo; Cheng, Juan; Wang, Chengkun; Zhang, Yanli; Shao, Lingxiao; Hu, Yongzhou; Han, Yifeng; Han, Feng; Li, Xin

    2017-08-15

    S-nitrosylation is a posttranslational modification of protein cysteine residues leading to the formation of S-nitrosothiols and its detection is crucial to understanding of redox regulation and NO-based signaling. Prototypical detection methods for S-nitrosylation are always carried out ex situ. However, the reversible nature and the tendency of transnitrosylation highlight the necessity of its probing in intact live biological contexts. Herein we provide a fluorogenic chemical probe for the detection of S-nitrosylation in live endothelial cells. The probe is weakly emissive alone and becomes highly fluorescent only after undergoing a reaction with S-nitrosothiols in live cellular environments. This probe features high degrees of specificity and desirable sensitivity. Furthermore, it has been successfully applied to image the dynamic change of protein S-nitrosylation in live endothelial cells. The applicability of the probe in complex biological systems has been additionally verified by imaging a known target of S-nitrosylation, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), in live cells. Due to the versatility exemplified, this probe holds great promise for exploring the role of protein S-nitrosylation in the pathophysiological process of a variety of vascular diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Iron (III) complexes of certain tetradentate phenolate ligands as ...

    Indian Academy of Sciences (India)

    Catechol 1,2-dioxygenase (CTD) and protocatechuate 3,4-dioxygenase (PCD) are bacterial non-heme iron enzymes, which catalyse the oxidative cleavage of catechols to cis, cis-muconic acids with the incorporation of molecular oxygen via a mechanism involving a high-spin ferric centre. The iron(III) complexes of tripodal ...

  3. Comparative study of efficacy, tolerability and compliance of oral iron preparations (iron edetate, iron polymatose complex) and intramuscular iron sorbitol in iron deficiency anaemia in children

    International Nuclear Information System (INIS)

    Afzal, M.; Qureshi, S.M.; Lutafullah, M.

    2009-01-01

    To compare the efficacy, tolerability and compliance of oral iron preparations(iron edetate and Iron polymaltose complex) with each other and with intramuscular iron sorbitol in iron deficiency anaemia in children. A Randomized Controlled Trial (RCT) was carried out at the Paediatric Department of Combined Military Hospital (CMH) from January 2006 to December 2007. In total 146 children, up to 12 years age having haemoglobin (Hb%) less than 8 gm% were included. They were randomly distributed into three groups. Group A(64 cases) received oral sodium iron edetate (SIE), Group B (40 cases) received oral iron polymaltose complex (IPC) and group C (42 cases) received intramuscular iron sorbitol (IS) in recommended dosages. Rise in Hb%>10 gm% was kept as desired target. Maximum duration of treatment planned was 2 weeks for parenteral iron (group C) and 12 weeks for oral iron (groups A and B). Haematological parameters- Hb%, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) were measured at induction followed at 2 weeks, 4 weeks, 8 weeks and 12 weeks after start of treatment. Compliance and drop out rates were determined on each visit. Data was analyzed using SPSS version 10. ANOVA was used to analyze difference in rise in Hb% at various intervals. Statistically significant increase in mean Hb%, MCV, MCHC after 02 weeks was observed in group C (IS). Rise in these parameters became significant in group A (SIE) and B (IPC) after 04 weeks. Persistent rise was observed in oral groups at 08 and 12 weeks. Rise in Hb% was much faster in group C (IS). It took 2 weeks to achieve mean Hb% > 10 gm% and compliance rate was 40.5%, while to achieve same target, duration required was 8 weeks in group A (SIE) and 12 weeks in group B (IPC) and compliance rate was 39% and 30% respectively. Adverse effects were much more common with group A (SIE) as compared to other two groups. Intramuscular iron sorbitol is a reliable and

  4. Dinitrogen binding and cleavage by multinuclear iron complexes.

    Science.gov (United States)

    McWilliams, Sean F; Holland, Patrick L

    2015-07-21

    The iron-molybdenum cofactor of nitrogenase has unprecedented coordination chemistry, including a high-spin iron cluster called the iron-molybdenum cofactor (FeMoco). Thus, understanding the mechanism of nitrogenase challenges coordination chemists to understand the fundamental N2 chemistry of high-spin iron sites. This Account summarizes a series of studies in which we have synthesized a number of new compounds with multiple iron atoms, characterized them using crystallography and spectroscopy, and studied their reactions in detail. These studies show that formally iron(I) and iron(0) complexes with three- and four-coordinate metal atoms have the ability to weaken and break the triple bond of N2. These reactions occur at or below room temperature, indicating that they are kinetically facile. This in turn implies that iron sites in the FeMoco are chemically reasonable locations for N2 binding and reduction. The careful evaluation of these compounds and their reaction pathways has taught important lessons about what characteristics make iron more effective for N2 activation. Cooperation of two iron atoms can lengthen and weaken the N-N bond, while three working together enables iron atoms to completely cleave the N-N bond to nitrides. Alkali metals (typically introduced into the reaction as part of the reducing agent) are thermodynamically useful because the alkali metal cations stabilize highly reduced complexes, pull electron density into the N2 unit, and make reduced nitride products more stable. Alkali metals can also play a kinetic role, because cation-π interactions with the supporting ligands can hold iron atoms near enough to one another to facilitate the cooperation of multiple iron atoms. Many of these principles may also be relevant to the iron-catalyzed Haber-Bosch process, at which collections of iron atoms (often promoted by the addition of alkali metals) break the N-N bond of N2. The results of these studies teach more general lessons as well. They

  5. Anthropogenic combustion iron as a complex climate forcer.

    Science.gov (United States)

    Matsui, Hitoshi; Mahowald, Natalie M; Moteki, Nobuhiro; Hamilton, Douglas S; Ohata, Sho; Yoshida, Atsushi; Koike, Makoto; Scanza, Rachel A; Flanner, Mark G

    2018-04-23

    Atmospheric iron affects the global carbon cycle by modulating ocean biogeochemistry through the deposition of soluble iron to the ocean. Iron emitted by anthropogenic (fossil fuel) combustion is a source of soluble iron that is currently considered less important than other soluble iron sources, such as mineral dust and biomass burning. Here we show that the atmospheric burden of anthropogenic combustion iron is 8 times greater than previous estimates by incorporating recent measurements of anthropogenic magnetite into a global aerosol model. This new estimation increases the total deposition flux of soluble iron to southern oceans (30-90 °S) by 52%, with a larger contribution of anthropogenic combustion iron than dust and biomass burning sources. The direct radiative forcing of anthropogenic magnetite is estimated to be 0.021 W m -2 globally and 0.22 W m -2 over East Asia. Our results demonstrate that anthropogenic combustion iron is a larger and more complex climate forcer than previously thought, and therefore plays a key role in the Earth system.

  6. Complexity of intravenous iron nanoparticle formulations: implications for bioequivalence evaluation.

    Science.gov (United States)

    Pai, Amy Barton

    2017-11-01

    Intravenous iron formulations are a class of complex drugs that are commonly used to treat a wide variety of disease states associated with iron deficiency and anemia. Venofer® (iron-sucrose) is one of the most frequently used formulations, with more than 90% of dialysis patients in the United States receiving this formulation. Emerging data from global markets outside the United States, where many iron-sucrose similars or copies are available, have shown that these formulations may have safety and efficacy profiles that differ from the reference listed drug. This may be attributable to uncharacterized differences in physicochemical characteristics and/or differences in labile iron release. As bioequivalence evaluation guidance evolves, clinicians should be educated on these potential clinical issues before a switch to the generic formulation is made in the clinical setting. © 2017 New York Academy of Sciences.

  7. Whey Peptide-Iron Complexes Increase the Oxidative Stability of Oil-in-Water Emulsions in Comparison to Iron Salts.

    Science.gov (United States)

    Caetano-Silva, Maria Elisa; Barros Mariutti, Lilian Regina; Bragagnolo, Neura; Bertoldo-Pacheco, Maria Teresa; Netto, Flavia Maria

    2018-02-28

    Food fortification with iron may favor lipid oxidation in both food matrices and the human body. This study aimed at evaluating the effect of peptide-iron complexation on lipid oxidation catalyzed by iron, using oil-in-water (O/W) emulsions as a model system. The extent of lipid oxidation of emulsions containing iron salts (FeSO 4 or FeCl 2 ) or iron complexes (peptide-iron complexes or ferrous bisglycinate) was evaluated during 7 days, measured as primary (peroxide value) and secondary products (TBARS and volatile compounds). Both salts catalyzed lipid oxidation, leading to peroxide values 2.6- to 4.6-fold higher than the values found for the peptide-iron complexes. The addition of the peptide-iron complexes resulted in the formation of lower amounts of secondary volatiles of lipid oxidation (up to 78-fold) than those of iron salts, possibly due to the antioxidant activity of the peptides and their capacity to keep iron apart from the lipid phase, since the iron atom is coordinated and takes part in a stable structure. The peptide-iron complexes showed potential to reduce the undesirable sensory changes in food products and to decrease the side effects related to free iron and the lipid damage of cell membranes in the organism, due to the lower reactivity of iron in the complexed form.

  8. Mössbauer study of some biological iron complexes

    Indian Academy of Sciences (India)

    Abstract. Some biological complexes containing iron are investigated experimentally at room temperature using the Mössbauer resonance. The complexes show quadrupole doublet and Kramer's degeneracy is found to exist. The electric field gradient, difference in s-electron densities and quadrupole coupling constant ...

  9. Iron complexes as electrocatalysts for the water oxidation reaction

    NARCIS (Netherlands)

    Kottrup, K.G.

    2018-01-01

    In this dissertation, the synthesis and characterization of a series of iron complexes based on different ligand platforms are described. The complexes are subsequently studied for their activity in catalytic water oxidation with the help of a variety of electroanalytical techniques. The

  10. Iron(III) complexes of certain tetradentate phenolate ligands as ...

    Indian Academy of Sciences (India)

    The single crystal X-ray crystal structures of four of the complexes have been deter- mined. One of the bis-phenolato complexes ... by soil bacteria of naturally occurring aromatic mole- cules and many aromatic environmental ... As the interaction of iron(III) with phenolate moie- ties of tyrosine residues plays an important role ...

  11. Iron and Manganese complexes for investigation of superoxide relevant processes

    OpenAIRE

    Dürr, Anna Katharina

    2010-01-01

    In the course of this work, stoichiometric superoxide reactions, as well as mechanistic details on catalytic superoxide dismutation with iron heme and iron and manganese non-heme complexes, respectively, have been elucidated. For the first time, quantitative investigations on superoxide reactions with metal centers have been achieved, particularly with regard to experiments under high pressure, at low temperatures and with variable superoxide concentrations resulting in crucial kinetic, therm...

  12. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present...... and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...

  13. Research of complex briquetted modifiers influence on cast iron properties

    Directory of Open Access Journals (Sweden)

    Наталя Валеріївна Сусло

    2016-07-01

    Full Text Available Such properties of cast iron as hardness and shock resistance are relevant and have been investigated. Some possible ways to improve these properties have been studied and solutions to the assigned tasks in accordance with modern trends have been found. The use of nano-dispersed modifiers is most promising in modification. The compositions of experimental complex briquetted modifiers have been developed. The technology of cast iron processing with complex briquetted modifiers has been developed. A series of experiments on the effect of a complex briquetted modifier introduced into cast iron on its properties were carried out. The rational content of components in the briquette that makes maximum use of the modifying effect and improves such service characteristics of cast iron as hardness, impact - and wear-resistance has been defined. Ways of a briquette destruction in metal have been explored. The effect of an organic binder amount on the destruction of a briquette and its dissolution in the melt has been investigated. Rational composition of the briquetted modifier that makes it possible to increase hardness and impact resistance of cast iron has been developed

  14. The Ru-NO bonding in nitrosyl-[poly(1-pyrazolyl)borate]ruthenium complexes: a theoretical insight based on EDA

    Energy Technology Data Exchange (ETDEWEB)

    Caramori, Giovanni F.; Kunitz, Andre G.; Coimbra, Daniel F.; Garcia, Leone C.; Fonseca, David E.P., E-mail: giovanni.caramori@ufsc.br [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Centro de Ciencias Fisicas e Matematicas. Dept. de Quimica

    2013-09-15

    The lability of NO{sup +} group in [TpRuCl{sub 2}(NO)]{sup q} (Tp = BL(pyrazol-1-yl){sub 3}) complexes was evaluated at the light of energy decomposition analysis (Su-Li EDA). The electronic effects of different pseudoaxial substituents (L = H, pyrazolyl anion, pyrazole, isoxazole and isothiazole) on the nature of Ru-NO bonding were evaluated considering complexes in ground (GS) and in metastable (MS1 and MS2) states. (Ru-NO){sup 6} bond nature in [TpRuCl{sub 2}(NO)]{sup q} (Tp = BL(pyrazol-1-yl){sub 3}) complexes is in essence covalent, but with a still significant electrostatic character. The nature of pseudoaxial substituents has a direct effect on the magnitude of (Ru-NO){sup 6} bonds. (author)

  15. Biologically relevant heterodinuclear iron-manganese complexes.

    Science.gov (United States)

    Carboni, Michaël; Clémancey, Martin; Molton, Florian; Pécaut, Jacques; Lebrun, Colette; Dubois, Lionel; Blondin, Geneviève; Latour, J-M

    2012-10-01

    The heterodinuclear complexes [Fe(III)Mn(II)(L-Bn)(μ-OAc)(2)](ClO(4))(2) (1) and [Fe(II)Mn(II)(L-Bn)(μ-OAc)(2)](ClO(4)) (2) with the unsymmetrical dinucleating ligand HL-Bn {[2-bis[(2-pyridylmethyl)aminomethyl

  16. Chemical Structure and Morphology of Magnetic Ultrafine Particles Synthesized from a Ternary Gaseous Mixture Involving Cobalt Tricarbonyl Nitrosyl

    Czech Academy of Sciences Publication Activity Database

    Morita, H.; Hattori, K.; Murafa, Nataliya; Šubrt, Jan

    2015-01-01

    Roč. 28, č. 3 (2015), s. 429-434 ISSN 0914-9244 R&D Projects: GA MŠk(CZ) 7AMB14SK178 Institutional support: RVO:61388980 Keywords : gas phase photochemical reaction * magnetic ultrafine particle * cobalt tricarbonyl nitrosyl * iron pentacarbonyl Subject RIV: CA - Inorganic Chemistry Impact factor: 0.857, year: 2015

  17. An iron complex with an unsupported Fe-Fe bond.

    Science.gov (United States)

    Murillo, Carlos A

    2009-01-01

    Full metal bonding: The reduction of a six-coordinate, mononuclear Werner-type iron(II) complex (see scheme) resulted in the isolation of a compound with an extraordinarily rare, unsupported Fe-Fe bond having an experimental Fe-Fe distance of 2.6869(6) A and a calculated bond order of 0.5.

  18. Polypyridyl iron(II) complexes showing remarkable photocytotoxicity ...

    Indian Academy of Sciences (India)

    Polypyridyl iron(II) complexes showing remarkable photocytotoxicity in visible light. ADITYA GARAIa, UTTARA BASUa, ILA PANTb, PATURU KONDAIAHb,∗ and AKHIL R CHAKRAVARTYa,∗. aDepartment of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India. bDepartment of Molecular ...

  19. Polypyridyl iron(II) complexes showing remarkable photocytotoxicity ...

    Indian Academy of Sciences (India)

    aditya

    Polypyridyl iron(II) complexes showing remarkable photocytotoxicity in visible light. ADITYA GARAI a. , UTTARA BASU a. , ILA PANT b. , PATURU KONDAIAH*. ,b. AND. AKHIL R. CHAKRAVARTY*. ,a a. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore. 560012, India. E-mail: ...

  20. Hafnium implanted in iron .2.Isolated Hafnium Nitrogen Complexes

    NARCIS (Netherlands)

    de Bakker, J.M.G.J.; Pleiter, F; Smulders, P.J M

    1993-01-01

    We have used the perturbed angular correlation technique to study the interaction of interstitially diffusing nitrogen atoms with substitutional hafnium atoms implanted in iron. It was found that after post-implantation of 250 eV nitrogen ions at 450 K, isolated HfVN(x) complexes with x = 1, 2 are

  1. Reactivity of (η3-allyl)dicarbonylnitrosyl iron complexes with ...

    African Journals Online (AJOL)

    The introduction of variable substituents exhibited diverse reactivities. Generally, it was observed that the reactivity decreased by increasing the size of substituentin (η3-allyl)dicarbonylnitrosyl iron complexes (1–9). Strong impact on the reactivity was observed due to substitution pattern of the allyl moiety. A considerable ...

  2. Theoretical Study of Spin Crossover in 30 Iron Complexes

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2016-01-01

    Spin crossover was studied in 30 iron complexes using density functional theory to quantify the direction and magnitude of dispersion, relativistic effects, zero-point energies, and vibrational entropy. Remarkably consistent entropy−enthalpy compensation was identified. Zero-point energies favor...

  3. Effects of Protein-Iron Complex Concentrate Supplementation on Iron Metabolism, Oxidative and Immune Status in Preweaning Calves

    Directory of Open Access Journals (Sweden)

    Robert Kupczyński

    2017-07-01

    Full Text Available The objective of this study was to determine the effects of feeding protein-iron complex (PIC on productive performance and indicators of iron metabolism, hematology parameters, antioxidant and immune status during first 35 days of a calf’s life. Preparation of the complex involved enzymatic hydrolysis of milk casein (serine protease from Yarrowia lipolytica yeast. Iron chloride was then added to the hydrolyzate and lyophilizate. Calves were divided into treated groups: LFe (low iron dose 10 g/day calf of protein-iron complex, HFe (height iron dose 20 g/day calf, and control group. Dietary supplements containing the lower dose of concentrate had a significant positive effect on iron metabolism, while the higher dose of concentrate resulted in increase of total iron binding capacity (TIBC, saturation of transferrin and decrease of and unsaturated iron binding capacity (UIBC, which suggest iron overload. Additionally, treatment with the lower dose of iron remarkably increased the antioxidant parameters, mainly total antioxidant (TAS and glutathione peroxidase activity (GPx. Higher doses of PIC were related to lower total antioxidant status. IgG, IgM, insulin, glucose, TNFα and IGF-1 concentration did not change significantly in either group after supplementation. In practice, the use of protein-iron complex concentrate requires taking into account the iron content in milk replacers and other feedstuffs.

  4. Effects of the η(5)-C5H4(i)Pr Ligand on the Properties Exhibited by Its Tungsten Nitrosyl Complexes.

    Science.gov (United States)

    Fabulyak, Diana; Baillie, Rhett A; Patrick, Brian O; Legzdins, Peter; Rosenfeld, Devon C

    2016-02-15

    Reaction of Na[η(5)-C5H4(i)Pr] with W(CO)6 in refluxing THF for 4 days generates a solution of Na[(η(5)-C5H4(i)Pr)W(CO)3] that when treated with N-methyl-N-nitroso-p-toluenesulfonamide at ambient temperatures affords (η(5)-C5H4(i)Pr)W(NO)(CO)2 (1) that is isolable in good yield as an analytically pure orange oil. Treatment of 1 with an equimolar amount of I2 in Et2O at ambient temperatures affords (η(5)-C5H4(i)Pr)W(NO)I2 (2) as a dark brown solid in excellent yield. Sequential treatment at low temperatures of 2 with 0.5 equiv of Mg(CH2CMe3)2 and Mg(CH2CH═CMe2)2 in Et2O produces the alkyl allyl complex, (η(5)-C5H4(i)Pr)W(NO)(CH2CMe3)(η(3)-CH2CHCMe2) (3), as a thermally sensitive yellow liquid. Complex 3 may also be synthesized, albeit in low yield, in one vessel at low temperatures by reacting 1 first with 1 equiv of PCl5 and then with the binary magnesium reagents specified above. Interestingly, similar treatment of 1 in Et2O with PCl5 and only 0.5 equiv of Mg(CH2CH═CMe2)2 results in the formation of the unusual complex (η(5)-C5H4(i)Pr)W(NO)(PCl2CMe2CH═CH2)Cl2 (4), which probably is formed via a metathesis reaction of the binary magnesium reagent with (η(5)-C5H4(i)Pr)W(NO)(PCl3)Cl2. The C-D activation of C6D6 by complex 3 has been investigated and compared to that exhibited by its η(5)-C5Me5, η(5)-C5Me4H, and η(5)-C5Me4(n)Pr analogues. Kinetic analyses of the various activations have established that the presence of the η(5)-C5H4(i)Pr ligand significantly increases the rate of the reaction, an outcome that can be attributed to a combination of steric and electronic factors. In addition, mechanistic studies have established that in solution 3 loses neopentane under ambient conditions to generate exclusively the 16e η(2)-diene intermediate complex (η(5)-C5H4(i)Pr)W(NO)(η(2)-CH2═CMeCH═CH2), which then effects the subsequent C-D activations. This behavior contrasts with that exhibited by the η(5)-C5Me5 analogue of 3 which forms both η(2

  5. Spin-crossover behavior of polymeric iron(III) complexes

    International Nuclear Information System (INIS)

    Maeda, Yonezo; Miyamoto, Makoto; Takashima, Yoshimasa; Oshio, Hiroaki

    1989-01-01

    Polymeric spin-crossover iron(III) complexes possessing poly(4-vinylpyridine), poly(N-vinylimidazole) or poly(octylmethacrylate-co-4-vinylpyridine) as ligand are prepared. In this experience enriched 57 Fe was used to get strong Moessbauer absorption. The enriched behavior of the complexes were examined by magnetic susceptibilities measurement, and Moessbauer and esr spectroscopies. Some of them show spin-state behavior over a wide range of temperature. Some of them show rapid spin-state interexchange compared to the Moessbauer time scale and others not. Spin-crossover behavior of polymeric complexes is characterized of wide spin-state transition temperature range

  6. Tailoring iron complexes for ethylene oligomerization and/or polymerization.

    Science.gov (United States)

    Zhang, Wenjuan; Sun, Wen-Hua; Redshaw, Carl

    2013-07-07

    Recent progress in the use of iron-based complex pre-catalysts for ethylene reactivity is reviewed, illustrating the current state-of-the-art and the potential usefulness of such systems for delivering solely ethylene oligomerization or polymerization products. The problems associated with the industrial use of late transition metal complex pre-catalysts are generally regarded as catalyst deactivation and the formation of more products of lower molecular weight at elevated temperature. These problems have been addressed for iron-based complex pre-catalysts via the fine tuning of substituents of existing ligands and/or the design of new ligand sets. Results revealed that modified bis(imino)pyridyliron dichlorides were capable of operating at elevated temperatures, and were capable of delivering highly linear polyethylene. Other new models of iron complexes have achieved high activity for ethylene oligomerization and/or polymerization. Particularly successful has been the use of the 2-iminophenanthrolyliron pre-catalyst, which have now been utilized in a 500 tonne pilot plant.

  7. Complexation of Flavonoids with Iron: Structure and Optical Signatures

    Science.gov (United States)

    Ren, Jun; Meng, Sheng; Lekka, Ch. E.; Kaxiras, Efthimios

    2008-03-01

    Flavonoids exhibit antioxidant behavior believed to be related to their metal ion chelation ability. We investigate the complexation mechanism of several flavonoids, quercetin, luteolin, galangin, kaempferol and chrysin with iron, the most abundant type of metal ions in the body, through first- principles electronic structure calculations based on Density Functional Theory (DFT). We find that the most likely chelation site for Fe is the 3-hydroxyl-4-carbonyl group, followed by 4- carbonyl-5-hydroxyl group and the 3'-4' hydroxyl (if present) for all the flavonoid molecules studied. Three quercetin molecules are required to saturate the bonds of a single Fe ion by forming six orthogonal Fe-O bonds, though the binding energy per molecule is highest for complexes consisting of two quercetin molecules and one Fe atom, in agreement with experiment. Optical absorption spectra calculated with time- dependent DFT serve as signatures to identify various complexes. For the iron-quercetin complexes, we find a redshift of the first absorbance peak upon complexation in good agreement with experiment; this behavior is explained by the narrowing of the optical gap of quercetin due to Fe(d)--O(p) orbital hybridization.

  8. Reactions associated with arene replacement in bis-(arene) iron complexes

    Czech Academy of Sciences Publication Activity Database

    Štíbr, Bohumil

    2012-01-01

    Roč. 716, OCTOBER (2012), s. 1-5 ISSN 0022-328X R&D Projects: GA ČR(CZ) GAP207/11/0705 Institutional support: RVO:61388980 Keywords : arene replacement reactions * ferracarboranes * iron-iron arene complexes * iron cyclohexadienyl complexes * metallacarboranes Subject RIV: CA - Inorganic Chemistry Impact factor: 2.000, year: 2012

  9. In vitro studies on interactions of iron salts and complexes with food-stuffs and medicaments.

    Science.gov (United States)

    Geisser, P

    1990-07-01

    It has been shown in the present study that food components such as phytic acid, oxalic acid, tannin, sodium alginate, choline and choline salts, vitamins A, D3 and E, soy oil and soy flour, do not undergo any interactions with iron(III)-hydroxide polymaltose complex (Ferrum Hausmann). Phytic acid, oxalic acid, tannin and sodium alginate, however, react with iron(II) or iron(III)-salts at pH values of 3.0, 5.5 and 8.0, giving rise to iron complexes. Trimethylamine-N-oxide, which is present in fish meal, reacts with iron(II)-sulphate to produce iron(III) reaction products; it does not react with iron(III)-hydroxide polymaltose complex. Special soybean flours show no irreversible adsorption or precipitation with iron(III)-hydroxyide polymaltose complex over the pH range 3.0-8.0, in contrast to iron(II)-sulphate. Antacids containing aluminium hydroxide, talc, ion exchange resins or other unabsorbable, insoluble components absorb iron(III)-hydroxide polymaltose complex in the pH range 3.0-8.0 in a reversible manner, while the strong adsorption or precipitation observed with iron(II)-sulphate at pH 8.0 is irreversible. No interaction was observed between the steroid hormones studied and iron(II)-sulphate or iron(III)-hydroxide polymaltose complex. On the basis of the measured compatibilities, iron(III)-hydroxide polymaltose complex can be administered orally simultaneously with many other drugs, without prejudicing the absorption of iron or of the other drug as is often seen with iron(II) and iron(III) salts.

  10. Iron-lactoferrin complex reduces iron-catalyzed off-flavor formation in powdered milk with added fish oil.

    Science.gov (United States)

    Ueno, Hiroshi M; Shiota, Makoto; Ueda, Noriko; Isogai, Tomoyuki; Kobayashi, Toshiya

    2012-08-01

    The iron-lactoferrin complex (FeLf) is useful for dietary iron supplementation. However, the effects of FeLf on iron-catalyzed off-flavors in lipid-containing food products have not been reported. In this study, we investigated the effects of FeLf on off-flavors development during the production and storage of powdered milk with added fish oil. Powdered milk samples were formulated with FeLf or iron (II) sulfate, then stored at 37 °C for 5 mo. A sensory evaluation revealed that FeLf delayed the development of oxidized flavor and reduced metallic taste in the powdered milk compared with iron (II) sulfate. Headspace gas chromatography-mass spectrometry analysis showed that oxidized volatile compounds, such as pentanal, hexanal, heptanal, octanal, 1-penten-3-one, (Z)-4-heptenal, (E, E)-2,4-heptadienal, and (E)-2-octenal, were less developed in the powdered milk containing FeLf than in that containing iron (II) sulfate. Iron and lactoferrin (Lf) were retained in the high-molecular-weight (>10000 Da) fraction of the reconstituted FeLf-containing powdered milk after its manufacture and storage, whereas the antigenicity of Lf was lost after ultrahigh-temperature processing at 120 °C for 5 s. These results suggest that FeLf reduces the iron-catalyzed off-flavors that develop during the production and storage of powdered milk. The stable iron-holding property of FeLf contributes to the inhibition of oxidized and metallic volatile formation, although the loss of Lf antigenicity did not affect the stability of FeLf and the iron-catalyzed formation of off-flavors in the powdered milk. Consequently, FeLf is a suitable candidate for the simultaneous supplementation of a single food with iron and fish oil. The supplementation of food products with iron and fish oil is a useful approach to redressing their inadequate intake in many populations. The iron-lactoferrin complex can protect food products against the off-flavors caused by iron-catalyzed lipid oxidation. Our results

  11. Altered S-nitrosylation of p53 is responsible for impaired antioxidant response in skeletal muscle during aging.

    Science.gov (United States)

    Baldelli, Sara; Ciriolo, Maria Rosa

    2016-12-20

    p53 transcriptional activity has been proposed to regulate both homeostasis and sarcopenia of skeletal muscle during aging. However, the exact molecular function of p53 remains to be clearly defined. We demonstrated a requirement of nuclear p53 S-nitrosylation in inducing a nitric oxide/PGC-1α-mediated antioxidant pathway in skeletal muscle. Importantly, mutant form of p53-DNA binding domain (C124S) did not undergo nuclear S-nitrosylation and failed in inducing the expression of antioxidant genes (i.e. SOD2 and GCLC). Moreover, we found that during aging the nuclear S-nitrosylation of p53 significantly declines in gastrocnemius/soleus leading to an impairment of redox homeostasis of skeletal muscle. We suggested that decreased level of nuclear neuronal nitric oxide synthase (nNOS)/Syntrophin complex, which we observed during aging, could be responsible for impaired nuclear S-nitrosylation. Taken together, our data indicate that altered S-nitrosylation of p53 during aging could be a contributing factor of sarcopenia condition and of other skeletal muscle pathologies associated with oxidative/nitrosative stress.

  12. Subcellular Distribution of S-Nitrosylated H-Ras in Differentiated and Undifferentiated PC12 Cells during Hypoxia.

    Science.gov (United States)

    Barbakadze, Tamar; Goloshvili, Galina; Narmania, Nana; Zhuravliova, Elene; Mikeladze, David

    2017-10-01

    Hypoxia or exposure to excessive reactive oxygen or nitrogen species could induce S-nitrosylation of various target proteins, including GTPases of the Ras-superfamily. Under hypoxic conditions, the Ras-protein is translocated to the cytosol and interacts with the Golgi complex, endoplasmic reticulum, mitochondria. The mobility/translocation of Ras depend on the cells oxidative status. However, the importance of relocated Snitrosylated- H-Ras (NO-H-Ras) in proliferation/differentiation processes is not completely understood. We have determined the content of soluble- and membrane-bound-NO-HRas in differentiated (D) and undifferentiated (ND) rat pheochromocytoma (PC12) cells under hypoxic and normoxic conditions. In our experimental study, we analyzed NO-H-Ras levels under hypoxic/normoxic conditions in membrane and soluble fractions of ND and D PC12 cells with/without nitric oxide donor, sodium nitroprusside (SNP) treatment. Cells were analyzed by the S-nitrosylated kit, immunoprecipitation, and Western blot. We assessed the action of NO-H-Ras on oxidative metabolism of isolated mitochondria by determining mitochondrial hydrogen peroxide generation via the scopoletin oxidation method and ATPproduction as estimated by the luminometric method. Hypoxia did not influence nitrosylation of soluble H-Ras in ND PC12 cells. Under hypoxic conditions, the nitrosylation of soluble-H-Ras greatly decreased in D PC12 cells. SNP didn't change the levels of nitrosylation of soluble-H-Ras, in either hypoxic or normoxic conditions. On the other hand, hypoxia, per se, did not affect the nitrosylation of membrane-bound-H-Ras in D and ND PC12 cells. SNP-dependent nitrosylation of membrane-bound-H-Ras greatly increased in D PC12 cells. Both unmodified normal and mutated H-Ras enhanced the mitochondrial synthesis of ATP, whereas the stimulatory effects on ATP synthesis were eliminated after S-nitrosylation of H-Ras. According to the results, it may be proposed that hypoxia can decrease S-nitrosylation

  13. An isoelectronic NO dioxygenase reaction using a nonheme iron(III)-peroxo complex and nitrosonium ion†

    Science.gov (United States)

    Yokoyama, Atsutoshi; Han, Jung Eun; Karlin, Kenneth D.; Nam, Wonwoo

    2014-01-01

    Reaction of a nonheme iron(III)-peroxo complex, [FeIII(14-TMC)(O2)]+, with NO+, a transformation which is essentially isoelectronic with that for nitric oxide dioxygenases [Fe(III)(O2•−) + NO], affords an iron(IV)-oxo complex, [FeIV(14-TMC)(O)]2+, and nitrogen dioxide (NO2), followed by conversion to an iron(III)-nitrato complex, [FeIII(14-TMC)(NO3)(F)]+. PMID:24394960

  14. Iron and cobalt complexes of 4, 4, 9, 9-tetramethyl-5, 8 ...

    Indian Academy of Sciences (India)

    Complexes 1 and 2 react with dioxygen at ambient condition to form the corresponding hydroxo- or oxo-bridged dinuclear cobalt(III) or iron(III) complexes. On the other hand, the iron(III)-catecholate complex (3) activate dioxygen to undergo oxidative C-C bond cleavage of catechol. The selective formation of extradiol ...

  15. Forms of iron in soils on basement complex rocks of Kaduna state in ...

    African Journals Online (AJOL)

    The forms of iron extracted by different methods were studied in soils developed on four basement complex rocks within Northern Guinea Savanna of Nigeria namely: migmatite gneisses, older granite, quartzites and mica schists. The study shows that forms of iron generally decreased in the order of total elemental iron ...

  16. Phenoxyl radical complexes of gallium, scandium, iron and manganese.

    Science.gov (United States)

    Adam, B; Bill, E; Bothe, E; Goerdt, B; Haselhorst, G; Hildenbrand, K; Sokolowski, A; Steenken, S; Weyhermüller, T; Wieghardt, K

    1997-02-01

    The hexadentate macrocyclic ligands 1,4,7-tris(3,5-dimethyl-2-hydroxybenzyl)-1,4,7-triazacyclononane (L CH 3H3 ), 1,4,7-tris(3,5-di-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononane (L(Bu) H3 ) and 1,4,7-tris(3-tert-butyl-5-methoxy-2-hydroxybenzyl)-1,4,7-triazacyclononane (L OCH 3-H3 ) form very stable octahedral neutral complexes LM(III) with trivalent (or tetravalent) metal ions (Ga(III) , Sc(III) , Fe(III) , Mn(III) , Mn(IV) ). The following complexes have been synthesized: [L(Bu) M], where M = Ga (1), Sc (2), Fe (3); [L(Bu) Mn(IV) ]PF6 (4'); [L OCH 3M], where M = Ga (1 a), Sc (2 a), Fe (3 a); [L OCH 3Mn(IV) ]PF6 (4 a'); [L CH 3M], where M = Sc (2 b), Fe (3 b), Mn(III) (4 b); [L CH 3Mn(IV) ]2 (ClO4 )3 (H3 O)(H2 O)3 (4 b'). An electrochemical study has shown that complexes 1, 2, 3, 1 a, 2 a and 3 a each display three reversible, ligand-centred, one-electron oxidation steps. The salts [L OCH 3Fe(III) ]ClO4 and [L OCH 3Ga(III) ]ClO4 , have been isolated as stable crystalline materials. Electronic and EPR spectra prove that these oxidations produce species containing one, two or three coordinated phenoxyl radicals. The Mössbauer spectra of 3 a and [3 a](+) show conclusively that both compounds contain high-spin iron(III) central ions. Temperature-dependent magnetic susceptibility measurements reveal that 3 a has an S = 5/2 and [3a](+) an S = 2 ground state. The latter is attained through intramolecular antiferromagnetic exchange coupling between a high-spin iron(III) (S1 = 5/2) and a phenoxyl radical (S2 = 1/2) (H = - 2JS1 S2 ; J = - 80 cm(-1) ). The manganese complexes undergo metal- and ligand-centred redox processes, which were elucidated by spectroelectrochemistry; a phenoxyl radical Mn(IV) complex [Mn(IV) L OCH 3](2+) is accessible. Copyright © 1997 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Nitrosyl hemoglobins: EPR above 80 K

    Energy Technology Data Exchange (ETDEWEB)

    Wajnberg, E.; Bemski, G.; El-Jaick, L.J.; Alves, O.C.

    1995-03-01

    The EPR spectra of nitrosyl hemoglobin and myoglobin in different conditions (native, denatured and lyophilized), as well as of hematin-NO were obtained in the temperature range of 80 K-280 K. There is a substantial and reversible.decrease of the areas of the EPR spectra of all the hemoglobin samples above 150 K. The interpretation of the results implies the existence of two conformational states in thermal equilibrium only one of which is EPR detectable. Thermodynamical parameters are determined for the hexa and penta-coordinated cases. (author). 25 refs, 3 figs.

  18. Nitrosyl hemoglobins: EPR above 80 K

    International Nuclear Information System (INIS)

    Wajnberg, E.; Bemski, G.; El-Jaick, L.J.; Alves, O.C.

    1995-03-01

    The EPR spectra of nitrosyl hemoglobin and myoglobin in different conditions (native, denatured and lyophilized), as well as of hematin-NO were obtained in the temperature range of 80 K-280 K. There is a substantial and reversible.decrease of the areas of the EPR spectra of all the hemoglobin samples above 150 K. The interpretation of the results implies the existence of two conformational states in thermal equilibrium only one of which is EPR detectable. Thermodynamical parameters are determined for the hexa and penta-coordinated cases. (author). 25 refs, 3 figs

  19. N2 Reduction and Hydrogenation to Ammonia by a Molecular Iron-Potassium Complex

    Science.gov (United States)

    Rodriguez, Meghan M.; Bill, Eckhard; Brennessel, William W.; Holland, Patrick L.

    2011-01-01

    The most common catalyst in the Haber-Bosch process for the hydrogenation of dinitrogen (N2) to ammonia is an iron surface promoted with K+, but soluble iron complexes have neither reduced the N-N bond of N2 to nitride nor produced large amounts of NH3 from N2. We report a molecular iron complex that reacts with N2 and a potassium reductant to give a complex with two nitrides, which are bound to iron and potassium cations. The product has a Fe3N2 core, implying that three iron atoms cooperate to break the N-N triple bond through a six-electron reduction. The nitride complex reacts with acid and with H2 to give substantial yields of N2-derived ammonia. These reactions, though not yet catalytic, give structural and spectroscopic insight into N2 cleavage and N-H bond-forming reactions of iron. PMID:22076372

  20. N₂reduction and hydrogenation to ammonia by a molecular iron-potassium complex.

    Science.gov (United States)

    Rodriguez, Meghan M; Bill, Eckhard; Brennessel, William W; Holland, Patrick L

    2011-11-11

    The most common catalyst in the Haber-Bosch process for the hydrogenation of dinitrogen (N(2)) to ammonia (NH(3)) is an iron surface promoted with potassium cations (K(+)), but soluble iron complexes have neither reduced the N-N bond of N(2) to nitride (N(3-)) nor produced large amounts of NH(3) from N(2). We report a molecular iron complex that reacts with N(2) and a potassium reductant to give a complex with two nitrides, which are bound to iron and potassium cations. The product has a Fe(3)N(2) core, implying that three iron atoms cooperate to break the N-N triple bond through a six-electron reduction. The nitride complex reacts with acid and with H(2) to give substantial yields of N(2)-derived ammonia. These reactions, although not yet catalytic, give structural and spectroscopic insight into N(2) cleavage and N-H bond-forming reactions of iron.

  1. Preparation of Monodisperse Iron Oxide Nanoparticles via the Synthesis and Decomposition of Iron Fatty Acid Complexes

    Directory of Open Access Journals (Sweden)

    Lin Chee-Cheng

    2009-01-01

    Full Text Available Abstract Iron fatty acid complexes (IFACs are prepared via the dissolution of porous hematite powder in hot unsaturated fatty acid. The IFACs are then decomposed in five different organic solvents under reflux conditions in the presence of the respective fatty acid. The XRD analysis results indicate that the resulting NPs comprise a mixture of wustite, magnetite, and maghemite phases. The solvents with a higher boiling point prompt the formation of larger NPs containing wustite as the major component, while those with a lower boiling point produce smaller NPs with maghemite as the major component. In addition, it is shown that unstable NPs with a mixed wustite–magnetite composition can be oxidized to pure maghemite by extending the reaction time or using an oxidizing agent.

  2. Kinetic, spectroscopic and chemical modification study of iron release from transferrin; iron(III) complexation to adenosine triphosphate

    International Nuclear Information System (INIS)

    Thompson, C.P.

    1985-01-01

    Amino acids other than those that serve as ligands have been found to influence the chemical properties of transferrin iron. The catalytic ability of pyrophosphate to mediate transferrin iron release to a terminal acceptor is largely quenched by modification non-liganded histine groups on the protein. The first order rate constants of iron release for several partially histidine modified protein samples were measured. A statistical method was employed to establish that one non-liganded histidine per metal binding domain was responsible for the reduction in rate constant. These results imply that the iron mediated chelator, pyrophosphate, binds directly to a histidine residue on the protein during the iron release process. EPR spectroscopic results are consistent with this interpretation. Kinetic and amino acid sequence studies of ovotransferrin and lactoferrin, in addition to human serum transferrin, have allowed the tentative assignment of His-207 in the N-terminal domain and His-535 in the C-terminal domain as the groups responsible for the reduction in rate of iron release. The above concepts have been extended to lysine modified transferrin. Complexation of iron(II) to adenosine triphosphate (ATP) was also studied to gain insight into the nature of iron-ATP species present at physiological pH. 31 P NMR spectra are observed when ATP is presented in large excess

  3. Proteomics investigation of endogenous S-nitrosylation in Arabidopsis

    International Nuclear Information System (INIS)

    Fares, Abasse; Rossignol, Michel; Peltier, Jean-Benoît

    2011-01-01

    Highlights: ► Identification and quantification of nitrosothiols. ► A first dataset of endogenously nitrosylated cysteines in Arabidopsis cells. ► Nitrosothiols display apolar motifs not located in close vicinity of cysteines. ► Salt stress alters the endogenous nitrosylation of specific cysteines in Arabidopsis. -- Abstract: S-Nitrosylation emerges as an important protein modification in many processes. However, most data were obtained at the protein level after addition of a NO donor, particularly in plants where information about the cysteines nitrosylated in these proteins is scarce. An adapted work-flow, combining the classical biotin switch method and labeling with isotope-coded affinity tags (ICAT), is proposed. Without addition of NO donor, a total of 53 endogenous nitrosocysteines was identified in Arabidopsis cells, in proteins belonging to all cell territories, including membranes, and covering a large panel of functions. This first repertoire of nitrosothiols in plants enabled also preliminary structural description. Three apolar motifs, not located in close vicinity of cysteines and accounting for half the dataset, were detected and are proposed to complement nitrosylation prediction algorithms, poorly trained with plant data to date. Analysis of changes induced by a brief salt stress showed that NaCl modified the nitrosylation level of a small proportion of endogenously nitrosylated proteins and did not concern all nitrosothiols in these proteins. The possible role of some NO targets in the response to salt stress was discussed.

  4. Microplasma synthesis on aluminum with additions of iron and nickel soluble complexes in electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Rogov, A.B., E-mail: alex-lab@bk.ru [Nikolaev Institute of Inorganic Chemistry. 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation); Mironov, I.V.; Terleeva, O.P.; Slonova, A.I. [Nikolaev Institute of Inorganic Chemistry. 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Alkaline homogeneous electrolyte with transition metals complexes. Black-Right-Pointing-Pointer Coatings contain metallic iron, nickel and their oxides in alumina-silica matrix. Black-Right-Pointing-Pointer Effect of Fe/Ni ratio on coatings properties and process characteristics. - Abstract: The microplasma synthesis of coatings containing iron and nickel from homogeneous electrolytes has been studied. For stabilization of transition metals in solution, it is proposed to use chelation. It was found that the synthesis of coatings using alternating current leads to the formation of metallic iron and nickel particles in addition to oxide phases. The iron and nickel complexes concentrations ratio in the electrolyte correlates with the coatings composition. Obtained coatings have been studied by scanning electron microscopy with X-ray microanalyser and by X-ray diffraction with Cu and Mo radiation. The metal content in the coating was determined spectrophotometrically from the absorption of iron thiocyanate complexes and nickel dimethylglyoxime complex.

  5. Iron fortification of flour with a complex ferric orthophosphate

    International Nuclear Information System (INIS)

    Hallberg, L.; Rossander-Hulthen, L.; Gramatkovski, E.

    1989-01-01

    The unexpectedly low bioavailability in humans of elemental iron powder prompted us to search for other Fe compounds suitable for Fe fortification of flour that fulfill the two requirements of insolubility in water (due to high water content of flour) and good bioavailability in humans. Systematic studies of compatibility, solubility, and bioavailability led to this study of a microcrystalline complex ferric orthophosphate (CFOP), Fe 3 H 8 (NH 4 )-(PO 4 )6.6H 2 O, a well-defined compound. This compound was labeled with 59 Fe, and the native Fe in meals was labeled with 55 FeCl3. The ratio of absorbed 59 Fe to absorbed 55 Fe is a direct measure of the fraction of CFOP that joins the nonheme Fe pool and that is made potentially available for absorption. The relative bioavailability of CFOP varied from 30% to 60% when labeled wheat rolls were served with different meals. The CFOP meets practical requirements of an Fe fortificant for flour well, with regard to both compatibility and bioavailability in humans

  6. Biogeochemical stability and reactions of iron-organic carbon complexes

    Science.gov (United States)

    Yang, Y.; Adhikari, D.; Zhao, Q.; Dunham-Cheatham, S.; Das, K.; Mejia, J.; Huang, R.; Wang, X.; Poulson, S.; Tang, Y.; Obrist, D.; Roden, E. E.

    2017-12-01

    Our core hypothesis is that the degradation rate of soil organic carbon (OC) is governed by the amount of iron (Fe)-bound OC, and the ability of microbial communities to utilize OC as an energy source and electron shuttle for Fe reduction that in turn stimulates reductive release of Fe-bound labile dissolved OC. This hypothesis is being systematically evaluated using model Fe-OC complexes, natural soils, and microcosm system. We found that hematite-bound aliphatic C was more resistant to reduction release, although hematite preferred to sorb more aromatic C. Resistance to reductive release represents a new mechanism that aliphatic soil OC was stabilized by association with Fe oxide. In other studies, pyrogenic OC was found to facilitate the reduction of hematite, by enhancing extracellular electron transport and sorbing Fe(II). For ferrihydrite-OC co-precipitates, the reduction of Fe and release of OC was closely governed by the C/Fe ratio in the system. Based on the XPS, XANES and XAFS analysis, the transformation of Fe speciation was heterogeneous, depending on the conformation and composition of Fe-OC complexes. For natural soils, we investigated the quantity, characteristics, and reactivity of Fe-bound OC in soils collected from 14 forests in the United States. Fe-bound OC contributed up to 57.8% of total OC in the forest soils. Under the anaerobic conditions, the reduction of Fe was positively correlated to the electron accepting capacity of OC. Our findings highlight the closely coupled dynamics of Fe and OC, with broad implications on the turnover of OC and biogeochemical cycles of Fe.

  7. Impact of iron porphyrin complexes when hydroprocessing algal HTL biocrude

    Energy Technology Data Exchange (ETDEWEB)

    Jarvis, Jacqueline M.; Sudasinghe, Nilusha M.; Albrecht, Karl O.; Schmidt, Andrew J.; Hallen, Richard T.; Anderson, Daniel B.; Billing, Justin M.; Schaub, Tanner M.

    2016-10-01

    We apply Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) for direct characterization of iron-porphyrins in hydrothermal liquefaction (HTL) biocrude oils derived from two algae: Tetraselmis sp. and cyanobacteria. The ironporphyrin compounds are shown to cause catalyst bed plugging during hydroprocessing due to iron deposition. Inductively-coupled plasma optical emission spectrometry (ICPOES) was utilized for iron quantitation in the plugged catalyst beds formed through hydroprocessing of the two HTL biocrudes and identifies an enrichment of iron in the upper five centimeters of the catalyst bed for Tetraselmis sp. (Fe=100,728 ppm) and cyanobacteria (Fe=115,450 ppm). Direct infusion FT-ICR MS analysis of the two HTL biocrudes with optimized instrument conditions facilitates rapid screening and identification of iron-porphyrins without prior chromatographic separation. With FT-ICR MS we identify 138 unique iron-porphyrin compounds in the two HTL biocrudes that are structurally similar to metal-porphyrins (e.g. Ni and V) observed in petroleum. No ironporphyrins are observed in the cyanobacteria HTL biocrude after hydroprocessing, which indicates that iron-porphyrin structures in the HTL biocrude are degraded during hydroprocessing. Hydrodemetallization reactions that occur through hydroprocessing of HTL biocrudes could be responsible for the decomposition of iron-porphyrin structures leading to metal deposition in the catalyst bed that result in catalyst deactivation and bed plugging, and must be addressed for effective upgrading of algal HTL biocrudes.

  8. Core size determination and structural characterization of intravenous iron complexes by cryogenic transmission electron microscopy.

    Science.gov (United States)

    Wu, Yong; Petrochenko, Peter; Chen, Lynn; Wong, Sook Yee; Absar, Mohammad; Choi, Stephanie; Zheng, Jiwen

    2016-05-30

    Understanding physicochemical properties of intravenous (IV) iron drug products is essential to ensure the manufacturing process is consistent and streamlined. The history of physicochemical characterization of IV iron complex formulations stretches over several decades, with disparities in iron core size and particle morphology as the major source of debate. One of the main reasons for this controversy is room temperature sample preparation artifacts, which affect accurate determination of size, shape and agglomeration/aggregation of nanoscale iron particles. The present study is first to report the ultra-fine iron core structures of four IV iron complex formulations, sodium ferric gluconate, iron sucrose, low molecular weight iron dextran and ferumoxytol, using a cryogenic transmission electron microscopy (cryo-TEM) preservation technique, as opposed to the conventional room temperature (RT-TEM) technique. Our results show that room temperature preparation causes nanoparticle aggregation and deformation, while cryo-TEM preserves IV iron colloidal suspension in their native frozen-hydrated and undiluted state. In contrast to the current consensus in literature, all four IV iron colloids exhibit a similar morphology of their iron oxide cores with a spherical shape, narrow size distribution and an average size of 2nm. Moreover, out of the four tested formulations, ferumoxytol exhibits a cluster-like community of several iron carbohydrate particles which likely accounts for its large hydrodynamic size of 25nm, measured with dynamic light scattering. Our findings outline a suitable method for identifying colloidal nanoparticle core size in the native state, which is increasingly important for manufacturing and design control of complex drug formulations, such as IV iron drug products. Published by Elsevier B.V.

  9. Determination of iron in plutonium by extraction of the Fe (2): Bathophenanthroline complex

    International Nuclear Information System (INIS)

    Pichotin, B.; Chasseur, Ph.

    1966-06-01

    The present report describes the method to determine micro quantities of iron in plutonium, by extraction with hexyl alcohol of the complex that give iron (II) with bathophenanthroline (4,7 diphenyl - 1.10 phenanthroline). The reagent has been applied to the determination of amounts of iron ranging from 1 to 10 μg in 20 ml of solvent The determination is made by spectrophotometry at 530 mμ. Others cations present do not interfere. (authors) [fr

  10. Clinical and biochemical features of some intravenous iron complexes

    Directory of Open Access Journals (Sweden)

    S. Yu. Abashin

    2013-01-01

    Full Text Available Most anemia cases associated with iron deficiency. There are various therapeutic approaches to compensate iron deficiency. In some cases,a rapid restore of body iron is required, which is only possible with intravenous administration. Now a number of intravenous iron preparations are available, and each of them has not only advantages. Considering the drugs side effects, there was a need for drugs with high efficiency, low immunogenicity, and minimal toxicity. One of the decisions was to create preparations based on maltose and isomaltose. Such new intravenous iron preparations are ferric carboxymaltose and iron isomaltoside. Currently, there are no available clinical data that isomaltose and maltose preparations differ significantly with respect to adverse reactions associated with their immunogenicity. Based on study results isomaltose preparations in patients with dextran sensibilization should be used with caution. This is not completely exclude the possibility that both of these drugs can be an immune response trigger with a different specificity than the one on dextran develops. Preparations based on maltose, sucrose and gluconate were neutral in immunoprecipitation assay with dextran-reactive antibodies that determines their preference for patients with dextran sensibilisation. Other important properties of ferric carboxymaltose are: convenience of application and lack of oxidative stress that are determined by the slow iron release.

  11. Clinical and biochemical features of some intravenous iron complexes

    Directory of Open Access Journals (Sweden)

    S. Yu. Abashin

    2014-07-01

    Full Text Available Most anemia cases associated with iron deficiency. There are various therapeutic approaches to compensate iron deficiency. In some cases,a rapid restore of body iron is required, which is only possible with intravenous administration. Now a number of intravenous iron preparations are available, and each of them has not only advantages. Considering the drugs side effects, there was a need for drugs with high efficiency, low immunogenicity, and minimal toxicity. One of the decisions was to create preparations based on maltose and isomaltose. Such new intravenous iron preparations are ferric carboxymaltose and iron isomaltoside. Currently, there are no available clinical data that isomaltose and maltose preparations differ significantly with respect to adverse reactions associated with their immunogenicity. Based on study results isomaltose preparations in patients with dextran sensibilization should be used with caution. This is not completely exclude the possibility that both of these drugs can be an immune response trigger with a different specificity than the one on dextran develops. Preparations based on maltose, sucrose and gluconate were neutral in immunoprecipitation assay with dextran-reactive antibodies that determines their preference for patients with dextran sensibilisation. Other important properties of ferric carboxymaltose are: convenience of application and lack of oxidative stress that are determined by the slow iron release.

  12. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  13. Merging Iron Catalysis and Biocatalysis-Iron Carbonyl Complexes as Efficient Hydrogen Autotransfer Catalysts in Dynamic Kinetic Resolutions

    KAUST Repository

    El-Sepelgy, Osama

    2016-09-29

    A dual catalytic iron/lipase system has been developed and applied in the dynamic kinetic resolution of benzylic and aliphatic secondary alcohols. A detailed study of the Knölker-type iron complexes demonstrated the hydrogen autotransfer of alcohols to proceed under mild reaction conditions and allowed the combination with the enzymatic resolution. Different racemic alcohols were efficiently converted to chiral acetates in good yields and with excellent enantioselectivities. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

  14. Site-selective detection of vibrational modes of an iron atom in a trinuclear complex

    Energy Technology Data Exchange (ETDEWEB)

    Faus, Isabelle, E-mail: faus@rhrk.uni-kl.de; Rackwitz, Sergej; Wolny, Juliusz A. [University of Kaiserslautern, Department of Physics (Germany); Banerjee, Atanu; Kelm, Harald; Krüger, Hans-Jörg [University of Kaiserslautern, Department of Chemistry (Germany); Schlage, Kai; Wille, Hans-Christian [DESY, PETRA III, P01 (Germany); Schünemann, Volker [University of Kaiserslautern, Department of Physics (Germany)

    2016-12-15

    Nuclear inelastic scattering (NIS) experiments on the trinuclear complex [{sup 57}Fe{L-N_4(CH_2Fc)_2} (CH{sub 3}CN){sub 2}](ClO{sub 4}){sub 2} have been performed. The octahedral iron ion in the complex was labelled with {sup 57}Fe and thereby exclusively the vibrational modes of this iron ion have been detected with NIS. The analysis of nuclear forward scattering (NFS) data yields a ferrous low-spin state for the {sup 57}Fe labelled iron ion. The simulation of the partial density of states (pDOS) for the octahedral low-spin iron(II) ion of the complex by density functional theory (DFT) calculations is in excellent agreement with the experimental pDOS of the complex determined from the NIS data obtained at 80 K. Thereby it was possible to assign almost each of the experimentally observed NIS bands to the corresponding molecular vibrational modes.

  15. Indefinitely stable iron(IV) cage complexes formed in water by air oxidation

    Science.gov (United States)

    Tomyn, Stefania; Shylin, Sergii I.; Bykov, Dmytro; Ksenofontov, Vadim; Gumienna-Kontecka, Elzbieta; Bon, Volodymyr; Fritsky, Igor O.

    2017-01-01

    In nature, iron, the fourth most abundant element of the Earth's crust, occurs in its stable forms either as the native metal or in its compounds in the +2 or +3 (low-valent) oxidation states. High-valent iron (+4, +5, +6) compounds are not formed spontaneously at ambient conditions, and the ones obtained synthetically appear to be unstable in polar organic solvents, especially aqueous solutions, and this is what limits their studies and use. Here we describe unprecedented iron(IV) hexahydrazide clathrochelate complexes that are assembled in alkaline aqueous media from iron(III) salts, oxalodihydrazide and formaldehyde in the course of a metal-templated reaction accompanied by air oxidation. The complexes can exist indefinitely at ambient conditions without any sign of decomposition in water, nonaqueous solutions and in the solid state. We anticipate that our findings may open a way to aqueous solution and polynuclear high-valent iron chemistry that remains underexplored and presents an important challenge.

  16. Multinuclear non-heme iron complexes for double-strand DNA cleavage

    NARCIS (Netherlands)

    Megens, Rik P.; van den Berg, Tieme A.; de Bruijn, A. Dowine; Feringa, Ben L.; Roelfes, Gerard

    2009-01-01

    The cytotoxicity of the antitumor drug BLM is believed to be related to the ability of the corresponding iron complex (Fe-BLM) to engage in oxidative double-strand DNA cleavage. The iron complex of the ligand N4Py (Fe-N4Py; N4Py - N,N-bis(2-pyridyl)-N-bis(2-pyridyl)methylamine has proven to be a

  17. IR and UV-visible spectra of iron(II) phthalocyanine complexes with ...

    African Journals Online (AJOL)

    In the IR spectra, the position of the νFeN4 band is linked to the coordination number; in the spectra of pentacoordinated complexes, its frequency is almost the same as that in the FePc spectrum but in hexacoordinated complexes, it moves to high frequencies. KEY WORDS: Iron(II) phthalocyanine complexes, Phosphine, ...

  18. Spin crossover studies in cationic complexes of iron by using Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Vadera, S.R.; Kumar, N.

    1990-01-01

    The spin transition in two new cationic complexes of iron, i.e. iron bipyridine formate, [Fe(bipy) 3 ](HCOO) 2 .5(HCOOH) and iron bipyridine tetrafluoro borate, [Fe(bipy) 3 ](BF 4 ) 2 .2H 2 O were studied by Moessbauer spectroscopy. From quadrupole splitting values, it was established that at different temperatures both complexes show the coexistence of both high spin state and low spin state at 300 K, while complete transformation to low spin state occurs at 77 K. Both compounds were prepared by electrochemical technique. (author) 12 refs.; 1 fig.; 1 tab

  19. Irradiation effects detected by Moessbauer spectroscopy in iron complexes

    International Nuclear Information System (INIS)

    Ladriere, J.

    1998-01-01

    The nature and the extent of the 60 Co gamma radiolysis of several iron coordination compounds have been analysed by Moessbauer absorption spectroscopy. The comparison of the radiolytic yields with the after effects observed by Moessbauer emission spectroscopy in similar 57 Co-doped compounds, supports the self-radiolysis model

  20. A Multiplex Enzymatic Machinery for Cellular Protein S-nitrosylation.

    Science.gov (United States)

    Seth, Divya; Hess, Douglas T; Hausladen, Alfred; Wang, Liwen; Wang, Ya-Juan; Stamler, Jonathan S

    2018-02-01

    S-nitrosylation, the oxidative modification of Cys residues by nitric oxide (NO) to form S-nitrosothiols (SNOs), modifies all main classes of proteins and provides a fundamental redox-based cellular signaling mechanism. However, in contrast to other post-translational protein modifications, S-nitrosylation is generally considered to be non-enzymatic, involving multiple chemical routes. We report here that endogenous protein S-nitrosylation in the model organism E. coli depends principally upon the enzymatic activity of the hybrid cluster protein Hcp, employing NO produced by nitrate reductase. Anaerobiosis on nitrate induces both Hcp and nitrate reductase, thereby resulting in the S-nitrosylation-dependent assembly of a large interactome including enzymes that generate NO (NO synthase), synthesize SNO-proteins (SNO synthase), and propagate SNO-based signaling (trans-nitrosylases) to regulate cell motility and metabolism. Thus, protein S-nitrosylation by NO in E. coli is essentially enzymatic, and the potential generality of the multiplex enzymatic mechanism that we describe may support a re-conceptualization of NO-based cellular signaling. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Water oxidation catalysis with nonheme iron complexes under acidic and basic conditions: homogeneous or heterogeneous?

    Science.gov (United States)

    Hong, Dachao; Mandal, Sukanta; Yamada, Yusuke; Lee, Yong-Min; Nam, Wonwoo; Llobet, Antoni; Fukuzumi, Shunichi

    2013-08-19

    Thermal water oxidation by cerium(IV) ammonium nitrate (CAN) was catalyzed by nonheme iron complexes, such as Fe(BQEN)(OTf)2 (1) and Fe(BQCN)(OTf)2 (2) (BQEN = N,N'-dimethyl-N,N'-bis(8-quinolyl)ethane-1,2-diamine, BQCN = N,N'-dimethyl-N,N'-bis(8-quinolyl)cyclohexanediamine, OTf = CF3SO3(-)) in a nonbuffered aqueous solution; turnover numbers of 80 ± 10 and 20 ± 5 were obtained in the O2 evolution reaction by 1 and 2, respectively. The ligand dissociation of the iron complexes was observed under acidic conditions, and the dissociated ligands were oxidized by CAN to yield CO2. We also observed that 1 was converted to an iron(IV)-oxo complex during the water oxidation in competition with the ligand oxidation. In addition, oxygen exchange between the iron(IV)-oxo complex and H2(18)O was found to occur at a much faster rate than the oxygen evolution. These results indicate that the iron complexes act as the true homogeneous catalyst for water oxidation by CAN at low pHs. In contrast, light-driven water oxidation using [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine) as a photosensitizer and S2O8(2-) as a sacrificial electron acceptor was catalyzed by iron hydroxide nanoparticles derived from the iron complexes under basic conditions as the result of the ligand dissociation. In a buffer solution (initial pH 9.0) formation of the iron hydroxide nanoparticles with a size of around 100 nm at the end of the reaction was monitored by dynamic light scattering (DLS) in situ and characterized by X-ray photoelectron spectra (XPS) and transmission electron microscope (TEM) measurements. We thus conclude that the water oxidation by CAN was catalyzed by short-lived homogeneous iron complexes under acidic conditions, whereas iron hydroxide nanoparticles derived from iron complexes act as a heterogeneous catalyst in the light-driven water oxidation reaction under basic conditions.

  2. Retardation of iron-cyanide complexes in the soil of a former manufactured gas plant site.

    Science.gov (United States)

    Sut, Magdalena; Repmann, Frank; Raab, Thomas

    2015-01-01

    The soil in the vicinities of former Manufactured Gas Plant (MGP) sites is commonly contaminated with iron-cyanide complexes (ferric ferrocyanide). The phenomenon of cyanide mobility in soil, according to the literature, is mainly governed by the dissolution and precipitation of ferric ferrocyanide, which is only slightly soluble (soil and the potential vertical movement of the solid iron-cyanide complexes, co-existing with the dissolution, sorption and precipitation reactions were investigated. Preliminary research conducted on a former MGP site implied colloidal transport of ferric ferricyanide from the initial deposition in the wastes layer towards the sandy loam material (secondary accumulation), which possibly retarded the mobility of cyanide (CN). A series of batch and column experiments were applied in order to investigate the retardation of iron-cyanide complexes by the sandy loam soil. Batch experiments revealed that in circumneutral pH conditions sandy loam material decreases the potassium ferro- and ferricyanide concentration. In column experiments a minor reduction in CN concentration was observed prior to addition of iron sulfide (FeS) layer, which induced the formation of the Prussian blue colloids in circumneutral pH conditions. Precipitated solid iron-cyanide complexes were mechanically filtered by the coherent structure of the investigated soil. Additionally, the reduction of the CN concentration of the percolation solutions by the sandy loam soil was presumably induced due to the formation of potassium manganese iron-cyanide (K2Mn[Fe(CN)6]).

  3. Moessbauer spectroscopy-nuclear hyperfine technique for studying dynamic chemical states of iron complexes

    International Nuclear Information System (INIS)

    Maeda, Y.

    2005-01-01

    A brief introduction of Moessbauer spectroscopy will be presented, followed by a discussion of the Moessbauer parameters, isomer shifts, quadrupole splittings, and spectral shapes of complexes in the presence of relaxation of the electronic states of the iron atoms. The usefulness of Moessbauer spectroscopy to demonstrate the dynamic phenomena of electronic states will be discussed in this lecture. (1) The Moessbauer spectra of mixed valence dinuclear and trinuclear iron complexes will be discussed in connection with the chemical structure of the complexes: The values of the quadrupole splittings and isomer shifts of [Fe II Fe III (bpmp) (ppa) 2 ](BF 4 ) 2 increase on raising the temperature, where Hbpmp represents 2,6-bis[bis(2- pyridylmethyl)aminoethyl]-4-methylphenol and ppa is 3-n-phenylpropionic acid. The spectra can be accounted for by postulating intramolecular electron exchange between two energetically inequivalent vibronic states Fe A 2+ Fe B 3+ and Fe A 3+ Fe B 2+ : The apparent time averaged valence states of the iron atoms are 2.2 and 2.8 on the Moessbauer time scale at 293 K. (2) The Moessbauer spectra of iron(III) spin-crossover complexes will be discussed in connection with the spin-transition rate and chemical structure of the complexes. The Moessbauer spectra of spin-crossover iron(III) complexes with LIESST (Light Induced Electronic Spin-State Transition) and of metallomesogens will be discussed to illustrate the extension of this research area by the use of Moessbauer spectroscopy.

  4. Light-evoked S-nitrosylation in the retina.

    Science.gov (United States)

    Tooker, Ryan E; Vigh, Jozsef

    2015-10-01

    Nitric oxide (NO) synthesis in the retina is triggered by light stimulation. NO has been shown to modulate visual signal processing at multiple sites in the vertebrate retina, via activation of the most sensitive target of NO signaling, soluble guanylate cyclase. NO can also alter protein structure and function and exert biological effects directly by binding to free thiol groups of cysteine residues in a chemical reaction called S-nitrosylation. However, in the central nervous system, including the retina, this reaction has not been considered to be significant under physiological conditions. Here we provide immunohistochemical evidence for extensive S-nitrosylation that takes place in the goldfish and mouse retinas under physiologically relevant light intensities, in an intensity-dependent manner, with a strikingly similar pattern in both species. Pretreatment with N-ethylmaleimide (NEM), which occludes S-nitrosylation, or with 1-(2-trifluromethylphenyl)imidazole (TRIM), an inhibitor of neuronal NO synthase, eliminated the light-evoked increase in S-nitrosylated protein immunofluorescence (SNI) in the retinas of both species. Similarly, light did not increase SNI, above basal levels, in retinas of transgenic mice lacking neuronal NO synthase. Qualitative analysis of the light-adapted mouse retina with mass spectrometry revealed more than 300 proteins that were S-nitrosylated upon illumination, many of which are known to participate directly in retinal signal processing. Our data strongly suggest that in the retina light-evoked NO production leads to extensive S-nitrosylation and that this process is a significant posttranslational modification affecting a wide range of proteins under physiological conditions. © 2015 Wiley Periodicals, Inc.

  5. Light-evoked S-nitrosylation in the retina

    Science.gov (United States)

    Tooker, Ryan E; Vigh, Jozsef

    2015-01-01

    Nitric oxide (NO) synthesis in the retina is triggered by light stimulation. NO has been shown to modulate visual signal processing at multiple sites in the vertebrate retina, via activation of the most sensitive target of NO signaling, soluble guanylate cyclase. NO can also alter protein structure and function and exert biological effects directly by binding to free thiol groups of cysteine residues in a chemical reaction called S-nitrosylation. However, in the central nervous system, including the retina, this reaction has not been considered to be significant under physiological conditions. Here we provide immunohistochemical evidence for extensive S-nitrosylation that takes place in the goldfish and mouse retinas under physiologically relevant light intensities, in an intensity-dependent manner, with a strikingly similar pattern in both species. Pre-treatment with NEM, which occludes S-nitrosylation, or with TRIM, an inhibitor of neuronal NO synthase, eliminated the light-evoked increase in S-nitrosylated protein immunofluorescence (SNI) in the retinas of both species. Similarly, light did not increase SNI, above basal levels, in retinas of transgenic mice lacking neuronal NO synthase. Qualitative analysis of the light-adapted mouse retina with mass spectrometry revealed more than 300 proteins that were S-nitrosylated upon illumination, many of which are known to participate directly in retinal signal processing. Our data strongly suggest that in the retina, light-evoked NO production leads to extensive S-nitrosylation and that this process is a significant post-translational modification affecting a wide range of proteins under physiological conditions. PMID:25823749

  6. Effect of atmospheric organic complexation on iron-bearing dust solubility

    Directory of Open Access Journals (Sweden)

    R. Paris

    2013-05-01

    Full Text Available Recent studies reported that the effect of organic complexation may be a potentially important process to be considered by models estimating atmospheric iron flux to the ocean. In this study, we investigated this process effect by a series of dissolution experiments on iron-bearing dust in the presence or the absence of various organic compounds (acetate, formate, oxalate, malonate, succinate, glutarate, glycolate, lactate, tartrate and humic acid as an analogue of humic like substances, HULIS typically found in atmospheric waters. Only 4 of tested organic ligands (oxalate, malonate, tartrate and humic acid caused an enhancement of iron solubility which was associated with an increase of dissolved Fe(II concentrations. For all of these organic ligands, a positive linear dependence of iron solubility to organic concentrations was observed and showed that the extent of organic complexation on iron solubility decreased in the following order: oxalate >malonate = tartrate > humic acid. This was attributed to the ability of electron donors of organic ligands and implies a reductive ligand-promoted dissolution. This study confirms that among the known atmospheric organic binding ligands of Fe, oxalate is the most effective ligand promoting dust iron solubility and showed, for the first time, the potential effect of HULIS on iron dissolution under atmospheric conditions.

  7. Proteomic identification of S-nitrosylated proteins in Arabidopsis

    DEFF Research Database (Denmark)

    Lindermayr, C.; Saalbach, G.; Durner, J.

    2005-01-01

    Although nitric oxide (NO) has grown into a key signaling molecule in plants during the last few years, less is known about how NO regulates different events in plants. Analyses of NO-dependent processes in animal systems have demonstrated protein S-nitrosylation of cysteine (Cys) residues to be ...... to be one of the dominant regulation mechanisms for many animal proteins. For plants, the principle of S-nitrosylation remained to be elucidated. We generated S-nitrosothiols by treating extracts from Arabidopsis (Arabidopsis thaliana) cell suspension cultures with the NO-donor S...

  8. The autoxidation activity of new mixed-ligand manganese and iron complexes with tripodal ligands

    NARCIS (Netherlands)

    van Gorkum, R.; Berding, J.; Tooke, D.M.; Spek, A.L.|info:eu-repo/dai/nl/156517566; Reedijk, J.; Bouwman, E.

    2007-01-01

    The activity of new manganese and iron complexes of dianionic tripodal ligands in the autoxidation of ethyl linoleate (EL) is reported. EL consumption rates were monitored using time-resolved FTIR and the degree of oligomerisation was determined by SEC. Almost all complexes showed the same trend in

  9. The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Mark L. Wells; Mary Jane Perry; William P. Cochlan; Charles G. Trick

    2006-11-18

    The central hypothesis of this project is that natural iron-complexing organic ligands in seawater differentially regulate iron availability to large (microplankton) and small (nano and picoplankton) class of phytoplankton and thereby strongly influence the potential carbon sequestration in High Nitrate Low Chlorophyll (HNLC) regions of the ocean. The primary project goals are to: 1) determine how different natural and synthetic Fe chelators affect Fe availability to phytoplankton species that are representative of offshore HNLC waters, 2) elucidate how the changes in absolute concentrations of these chelators affect the longer-term ecosystem response to alleviation of Fe limitation, and 3) ascertain how changes in the ligand composition affect rates of cell sinking and aggregation - representative measures of the efficiency of carbon sequestration to the deep.

  10. A child with severe iron-deficiency anemia and a complex TMPRSS6 genotype.

    Science.gov (United States)

    Capra, Anna Paola; Ferro, Elisa; Cannavò, Laura; La Rosa, Maria Angela; Zirilli, Giuseppina

    2017-10-01

    We report a case of a 7-year-old girl with severe hypochromic microcytic anemia, who was unresponsive to classical iron supplements. We suspected IRIDA, iron-refractory iron-deficiency anemia, a genetic iron metabolism disorder, caused by TMPRSS6 variations. TMPRSS6 encodes matriptase-2, a negative regulator of hepcidin, and its pathological variants are related to normal to high levels of hepcidin. We analyzed the TMPRSS6 gene and we improved clinical management of the patient, selecting the appropriate supplementation therapy. Intervention & Technique: The parenteral iron therapy was started, but the patient was only partially responsive and the anemia persisted. To confirm the diagnosis, the TMPRSS6 gene sequence was analyzed by DNA sequencing and other relevant biochemical parameters were evaluated. The TMPRSS6 sequence analysis showed a complex genotype with a rare heterozygous missense variant, in addition to other common polymorphisms. The serum hepcidin value was normal. We unexpectedly observed a normalization of patient's hemoglobin (Hb) levels only after liposomal iron treatment. The proband was symptomatic for IRIDA during a critical phase of growth and development, but we did not find a clearly causative genotype. A long-term result, improving stably patient's Hb levels, was obtained only after liposomal iron supplementation. Children may be at greater risk for iron deficiency and the degree of anemia as well as the response to the iron supplements varies markedly patient to patient. Here, we show the importance of comprehensive study of these patients in order to collect useful information about genotype-phenotype association of genes involved in iron metabolism.

  11. Litterfall dynamics in a iron-rich rock outcrop complex in the southeastern portion of the Iron Quadrangle of Brazil

    Directory of Open Access Journals (Sweden)

    Eduardo André Ribeiro Valim

    2013-06-01

    Full Text Available Ecosystems on cangas (duricrust present considerable heterogeneity of habitats due to microtopographic variations, soil accumulation and a variety of plant functional groups. Therefore, spatial and temporal ecosystem processes such as litterfall are to be expected to be large, and the absence of a level of productivity represents all the facets of iron-rich landscapes. We investigated litterfall in a iron-rich rock complex in the Iron Quadrangle of Brazil, with habitats formed on different evolutionary stages of the soil, resulting in a gradient of biomass, canopy cover and community structure. The measurements were made in open field areas, dominated by herb-shrub vegetation and interspersed with islands of dense vegetation in which there were individual trees, as well as in areas of semideciduous forest. The litterfall, especially that of leaf litter, followed the gradient of woody cover and was approximately two times greater in the forest formation. However, the spatial and temporal variations in deposition were greatest in the herb-shrub areas and least in the semideciduous forest area, intermediate values being obtained for the tree island areas. The peaks in litterfall also varied among habitats, occurring in some periods of the rainy season and during the transition from rainy to dry in the herb-shrub and tree island areas, whereas they occurred at the end of the dry season in the semideciduous forest area. The results show significant differences in the patterns of litterfall among different physiognomies within the same iron-rich rock complex, indicating the need for expanded studies, focusing on the flow of matter and energy in such environments.

  12. New Discoveries in the Search for Iron-Complex Globular Clusters

    Science.gov (United States)

    Johnson, Christian; Caldwell, Nelson; Rich, R. Michael; Mateo, Mario; Bailey, Jeb; Walker, Matthew G.; M2FS Team

    2018-01-01

    A growing number of Galactic globular clusters have been discovered that possess large intrinsic [Fe/H] and heavy element abundance variations. These "iron-complex" clusters are among the most massive in the Galaxy, and frequently exhibit extended blue horizontal branches and low metallicities. Additionally, a handful of clusters with [Fe/H] > -1 may also have large metallicity spreads (e.g., Terzan 5), but are instead characterized by having bimodal red horizontal brances. We present chemical composition analyses of several potential iron-complex clusters spanning [Fe/H] = -1.8 to -0.8, and discover that horizontal branch morphology alone is insufficient to identify clusters with heavy element abundance variations. However, we find that several of these clusters contain 4-5 chemically distinct populations, and the outer halo cluster NGC 6229 is added to the growing list of iron-complex clusters that may be the remnant cores of former dwarf spheroidal galaxies.

  13. NHC Versus Pyridine: How “Teeth” Change the Redox Behavior of Iron(II) Complexes

    KAUST Repository

    Weiss, Daniel T.

    2015-10-06

    A series of octahedral iron(II) complexes with tetradentate NHC/pyridine hybrid ligands containing up to three pyridyl units was designed to study the influence of NHC and pyridine donors on the electronic structure of the metal center. Structural analysis of the iron complexes by NMR spectroscopy and single-crystal X-ray diffraction reveals different coordination modes of the ligand depending on the linkage of the different donor moieties. The oxidation potentials of all complexes correlate linearly with the number of NHC moieties coordinated to iron, as shown by cyclic voltammetry. The influence, although minor, of structural properties on the oxidation potential and (in one case) the influence of the oxidation state of the coordination geometry of the hybrid ligand are also demonstrated.

  14. Complexation equilibria and spectrophotometric determination of iron(III) with 1-amino-4-hydroxyanthraquinone.

    Science.gov (United States)

    Abu-Bakr, M S; Sedaira, H; Hashem, E Y

    1994-10-01

    The complex equilibria of iron(III) with 1-amino-4-hydroxyanthraquinone (AMHA) were studied spectrophotometrically in 40% (v/v) ethanol and an ionic strength of 0.1M (NaClO(4)). The complexation reactions were demonstrated and characterized using graphical logarithmic analysis of the absorbance-pH graphs. A simple, rapid, selective and sensitive method for the spectrophotometric determination of trace amounts of Fe(III) is developed based on the formation of Fe(AMHA) complex at pH 2.5 (lambda(max) = 640 nm, epsilon approximately = 2.1 x 10(4) L. mol(-1) . cm(-1)) in the presence of a large number of foreign ions. Interferences caused by palladium(II) was masked by the addition of cyanide ions. The method has been applied to the determination of iron in some synthetic samples and polymetallic iron ores.

  15. Reversible S-nitrosylation in an engineered azurin

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Shiliang; Liu, Jing; Cowley, Ryan E.; Hosseinzadeh, Parisa; Marshall, Nicholas M.; Yu, Yang; Robinson, Howard; Nilges, Mark J.; Blackburn, Ninian J.; Solomon, Edward I.; Lu, Yi

    2016-04-25

    S-Nitrosothiols are known as reagents for NO storage and transportation and as regulators in many physiological processes. Although the S-nitrosylation catalysed by haem proteins is well known, no direct evidence of S-nitrosylation in copper proteins has been reported. Here, we report reversible insertion of NO into a copper–thiolate bond in an engineered copper centre in Pseudomonas aeruginosa azurin by rational design of the primary coordination sphere and tuning its reduction potential by deleting a hydrogen bond in the secondary coordination sphere. The results not only provide the first direct evidence of S-nitrosylation of Cu(II)-bound cysteine in metalloproteins, but also shed light on the reaction mechanism and structural features responsible for stabilizing the elusive Cu(I)–S(Cys)NO species. The fast, efficient and reversible S-nitrosylation reaction is used to demonstrate its ability to prevent NO inhibition of cytochrome bo3 oxidase activity by competing for NO binding with the native enzyme under physiologically relevant conditions.

  16. The synthesis and structural characterization of the technetium nitrosyl complexes [TcCl(NO)(SC5H4N)(PPh3)2] and [Tc(NO)(SC5H4N)2(PPh3)

    Science.gov (United States)

    Nicholson, Terrence L.; Mahmood, Ashfaq; Muller, Peter; Davison, Alan; Storm-Blanchard, Shannon; Jones, Alun G.

    2011-01-01

    The reaction of the Tc(I) complex [Tc(NO)Cl2(HOMe)(PPh3)2] with stoichiometric amounts of 2-mercatopyridine and a proton scavenger yields [Tc(NO)Cl(Spy)(PPh3)2] or [Tc(NO)(Spy)2(PPh3)], depending upon quantities of ligands employed. These two complexes have been structurally characterized. The small bite angles of the bidentate mercaptopyridine ligands cause significant deviation from octahedral coordination geometry. PMID:23750048

  17. In vivo anti-radiation activities of the Ulva pertusa polysaccharides and polysaccharide-iron(III) complex.

    Science.gov (United States)

    Shi, Jinming; Cheng, Cuilin; Zhao, Haitian; Jing, Jing; Gong, Ning; Lu, Weihong

    2013-09-01

    Polysaccharides with different molecular weights were extracted from Ulva pertusa and fractionated by ultrafiltration. Iron(III) complex of the low molecular-weight U. pertusa polysaccharides were synthesized. Atomic absorption spectrum showed that the iron content of iron(III)-polysaccharide complex was 27.4%. The comparison between U. pertusa polysaccharides and their iron(III) complex showed that iron chelating altered the structural characteristics of the polysaccharides. The bioactivity analysis showed that polysaccharide with low molecular weight was more effective than polysaccharide with high molecular weight in protecting mice from radiation induced damages on bone marrow cells and immune system. Results also proved that the anti-radiation and anti-oxidative activity of iron(III) complex of low molecular-weight polysaccharides were not less than that of low molecular-weight polysaccharides. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Effect of Low-Dose Ferrous Sulfate vs Iron Polysaccharide Complex on Hemoglobin Concentration in Young Children With Nutritional Iron-Deficiency Anemia: A Randomized Clinical Trial.

    Science.gov (United States)

    Powers, Jacquelyn M; Buchanan, George R; Adix, Leah; Zhang, Song; Gao, Ang; McCavit, Timothy L

    2017-06-13

    Iron-deficiency anemia (IDA) affects millions of persons worldwide, and is associated with impaired neurodevelopment in infants and children. Ferrous sulfate is the most commonly prescribed oral iron despite iron polysaccharide complex possibly being better tolerated. To compare the effect of ferrous sulfate with iron polysaccharide complex on hemoglobin concentration in infants and children with nutritional IDA. Double-blind, superiority randomized clinical trial of infants and children aged 9 to 48 months with nutritional IDA (assessed by history and laboratory criteria) that was conducted in an outpatient hematology clinic at a US tertiary care hospital from September 2013 through November 2015; 12-week follow-up ended in January 2016. Three mg/kg of elemental iron once daily as either ferrous sulfate drops or iron polysaccharide complex drops for 12 weeks. Primary outcome was change in hemoglobin over 12 weeks. Secondary outcomes included complete resolution of IDA (defined as hemoglobin concentration >11 g/dL, mean corpuscular volume >70 fL, reticulocyte hemoglobin equivalent >25 pg, serum ferritin level >15 ng/mL, and total iron-binding capacity polysaccharide complex group). From baseline to 12 weeks, mean hemoglobin increased from 7.9 to 11.9 g/dL (ferrous sulfate group) vs 7.7 to 11.1 g/dL (iron complex group), a greater difference of 1.0 g/dL (95% CI, 0.4 to 1.6 g/dL; P polysaccharide complex resulted in a greater increase in hemoglobin concentration at 12 weeks. Once daily, low-dose ferrous sulfate should be considered for children with nutritional iron-deficiency anemia. clinicaltrials.gov Identifier: NCT01904864.

  19. Iron(III) and copper(II) complexes of trans-bis(ferrocenyl)porphyrin

    Indian Academy of Sciences (India)

    Iron(III) and copper(II) complexes of trans-bis(ferrocenyl)porphyrin: Effect of metal ions on long-range electronic communication. Dipankar Sahoo Sankar Prasad Rath. Volume 127 Issue ... Keywords. Ferrocenylporphyrin; electrochemistry; spectro-electrochemistry; electrochemical conjugation; X-ray structure determination.

  20. Iron(III) and copper(II) complexes of trans-bis(ferrocenyl)porphyrin ...

    Indian Academy of Sciences (India)

    Iron(III) and copper(II) complexes of trans-bis(ferrocenyl)porphyrin: Effect of metal ions on long-range electronic communication. DIPANKAR SAHOO and SANKAR PRASAD RATH∗. Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India e-mail: sprath@iitk.ac.in. MS received 12 December ...

  1. The accuracy of geometries for iron porphyrin complexes from density functional theory

    DEFF Research Database (Denmark)

    Rydberg, Patrik Åke Anders; Olsen, Lars

    2009-01-01

    Iron porphyrin complexes are cofactors in many important proteins such as cytochromes P450, hemoglobin, heme peroxidases, etc. Many computational studies on these systems have been done over the past decade. In this study, the performance of some of the most commonly used density functional theor...

  2. Mononuclear non-heme iron (III) complexes of linear and tripodal ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 2. Mononuclear non-heme iron(III) complexes of linear and tripodal tridentate ligands as functional models for catechol dioxygenases: Effect of -alkyl substitution on regioselectivity and reaction rate. Mallayan Palaniandavar Kusalendiran Visvaganesan.

  3. Visible lights induced polymerization reactions: interactions between rose bengal and iron aren complex

    International Nuclear Information System (INIS)

    Burget, D.; Grotzinger, C.; Jacques, P.; Fouassier, J.P.

    1999-01-01

    The present paper is devoted to an investigation of the interactions between Rose Bengal (RB) and an Iron aren (Irg(+)) complex that are usable in visible light induced polymerization reactions. Steady state and flash photolysis experiments were performed in order to elucidate the nature of the intermediates formed after light excitation. A complete scheme of evolution of the excited states is discussed

  4. [Influence of different iron compounds on lipid complex of vitamin fortified wheat flour under storage].

    Science.gov (United States)

    Vorob'eva, I S; Baĭkov, V G; Vorob'eva, V M; Shatniuk, L N

    2009-01-01

    Influence of different iron compounds at combined vitamin fortification on hygienic and biochemical properties of freshly grounded first-class wheat flour under storage was studied. It proved, that more intensive oxidative and hydrolytic processes take place in the lipid complex of the flour, fortified with ferrous sulfate heptahydrate.

  5. Iron(III) and aluminium(III) complexes with substituted salicyl-aldehydes and salicylic acids.

    Science.gov (United States)

    Nurchi, Valeria M; Crespo-Alonso, Miriam; Toso, Leonardo; Lachowicz, Joanna I; Crisponi, Guido; Alberti, Giancarla; Biesuz, Raffaela; Domínguez-Martín, Alicia; Niclós-Gutíerrez, Juan; González-Pérez, Josefa M; Zoroddu, M Antonietta

    2013-11-01

    The chelating properties toward iron(III) and aluminium(III) of variously substituted salicyl-aldehydes and salicylic acids have been evaluated, together with the effect of methoxy and nitro substituents in ortho and para position with respect to the phenolic group. The protonation and iron and aluminium complex formation equilibria have been studied by potentiometry, UV-visible spectrophotometry and (1)H NMR spectroscopy. The overall results highlight that salicyl-aldehydes present good chelating properties toward iron(III), with pFe ranging from 14.2 with nitro to 15.7 with methoxy substituent, being ineffective toward aluminium; the pFe values for salicylic acids are generally lower than those for salicyl-aldehydes, and about 4 units higher than the corresponding pAl values. The effect of the two substituents on the chelating properties of the ligands can be rationalized in terms of the Swain-Lupton treatment which accounts for the field and resonance effects. The structural characterization of the 1:2 iron complex with p-nitro salicylic acid shows that iron(III) ion exhibits an octahedral surrounding where two salicylate chelating ligands supply two O-phenolate and two O-carboxylate donor atoms in a roughly equatorial plane. The trans-apical sites are occupied by two aqua ligands. © 2013.

  6. Arene activation by a nonheme iron(III)-hydroperoxo complex: pathways leading to phenol and ketone products.

    Science.gov (United States)

    Faponle, Abayomi S; Banse, Frédéric; de Visser, Sam P

    2016-07-01

    Iron(III)-hydroperoxo complexes are found in various nonheme iron enzymes as catalytic cycle intermediates; however, little is known on their catalytic properties. The recent work of Banse and co-workers on a biomimetic nonheme iron(III)-hydroperoxo complex provided evidence of its involvement in reactivity with arenes. This contrasts the behavior of heme iron(III)-hydroperoxo complexes that are known to be sluggish oxidants. To gain insight into the reaction mechanism of the biomimetic iron(III)-hydroperoxo complex with arenes, we performed a computational (density functional theory) study. The calculations show that iron(III)-hydroperoxo reacts with substrates via low free energies of activation that should be accessible at room temperature. Moreover, a dominant ketone reaction product is observed as primary products rather than the thermodynamically more stable phenols. These product distributions are analyzed and the calculations show that charge interaction between the iron(III)-hydroxo group and the substrate in the intermediate state pushes the transferring proton to the meta-carbon atom of the substrate and guides the selectivity of ketone formation. These studies show that the relative ratio of ketone versus phenol as primary products can be affected by external interactions of the oxidant with the substrate. Moreover, iron(III)-hydroperoxo complexes are shown to selectively give ketone products, whereas iron(IV)-oxo complexes will react with arenes to form phenols instead.

  7. Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942.

    Science.gov (United States)

    Fraser, Jared M; Tulk, Sarah E; Jeans, Jennifer A; Campbell, Douglas A; Bibby, Thomas S; Cockshutt, Amanda M

    2013-01-01

    Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ~42 IsiA : Photosystem I in Synechococcus PCC 7942 and ~12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes.

  8. Iron

    Science.gov (United States)

    ... Share: Search the ODS website Submit Search NIH Office of Dietary Supplements Consumer Datos en español Health ... eating a variety of foods, including the following: Lean meat, seafood, and poultry. Iron-fortified breakfast cereals ...

  9. The autoxidation activity of new mixed-ligand manganese and iron complexes with tripodal ligands

    OpenAIRE

    van Gorkum, R.; Berding, J.; Tooke, D.M.; Spek, A.L.; Reedijk, J.; Bouwman, E.

    2007-01-01

    The activity of new manganese and iron complexes of dianionic tripodal ligands in the autoxidation of ethyl linoleate (EL) is reported. EL consumption rates were monitored using time-resolved FTIR and the degree of oligomerisation was determined by SEC. Almost all complexes showed the same trend in the autoxidation of EL. After a short induction time, the reaction started at a relatively high constant rate; later, this rate changes to a lower rate, which was again constant and on average was ...

  10. Iron and cobalt complexes of 4,4,9,9-tetramethyl-5,8-diazadodecane ...

    Indian Academy of Sciences (India)

    and a biomimetic iron(III)-catecholate complex [FeIII(HL)(DBC)] (3) of a dioxime ligand (H2L = 4,4,9,9- tetramethyl-5,8-diazadodecane-2,11-dione dioxime and DBCH2 = 3,5-di-tert-butylcatechol) were synthesized and characterized. X-ray single-crystal structures of both the dinuclear complexes exhibit an out-of-plane oxi-.

  11. Biphenolate Iron (II) Complexes with Intramolecularly Coordinating Nitrogen Lewis Bases

    NARCIS (Netherlands)

    Koten, G. van; Brandts, J.A.M.; Janssen, M.D.; Hogerheide, M.P.; Boersma, J.; Spek, A.L.

    1999-01-01

    The synthesis and characterisation of a novel Fe(II) bisphenolate complex [Fe(OC{6}H{4}CH{2}NMe{2}-2){2}]{2} (1) from [Na(OC{6}H{4}CH{2}NMe{2}-2)] and anhydrous FeCl{2} is reported. The solid state structure has been elucidated by single crystal X-ray analysis and shows a dimeric structure with two

  12. Major deviations of iron complexation during 22 days of a mesoscale iron enrichment in the open Southern Ocean

    NARCIS (Netherlands)

    Boye, Marie; Nishioka, Jun; Croot, Peter L.; Laan, Patrick; Timmermans, Klaas R.; Baar, Hein J.W. de

    2005-01-01

    The speciation of strongly chelated iron during the 22-day course of an iron enrichment experiment in the Atlantic sector of the Southern Ocean deviates strongly from ambient natural waters. Three iron additions (ferrous sulfate solution) were conducted, resulting in elevated dissolved iron

  13. Serum albumin forms a lactoferrin-like soluble iron-binding complex in presence of hydrogen carbonate ions.

    Science.gov (United States)

    Ueno, Hiroshi M; Urazono, Hiroshi; Kobayashi, Toshiya

    2014-02-15

    The iron-lactoferrin complex is a common food ingredient because of its iron-solubilizing capability in the presence of hydrogen carbonate ions. However, it is unclear whether the formation of a stable iron-binding complex is limited to lactoferrin. In this study, we investigated the effects of bovine serum albumin (BSA) on iron solubility and iron-catalyzed lipid oxidation in the presence of hydrogen carbonate ions. BSA could solubilize >100-fold molar equivalents of iron at neutral pH, exceeding the specific metal-binding property of BSA. This iron-solubilizing capability of BSA was impaired by thermally denaturing BSA at ≥ 70 °C for 10 min at pH 8.5. The resulting iron-BSA complex inhibited iron-catalyzed oxidation of soybean oil in a water-in-oil emulsion measured using the Rancimat test. Our study is the first to show that BSA, like lactoferrin, forms a soluble iron-binding complex in the presence of hydrogen carbonate ions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    International Nuclear Information System (INIS)

    Arya, S. P.; Mahajan, M.

    1998-01-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 μg ml -1 . Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C [it

  15. Iron Complexes of Peptide Conjugates: Theoretical and Spectroscopic Study

    Czech Academy of Sciences Publication Activity Database

    Šebestík, Jaroslav; Šafařík, Martin; Bouř, Petr

    2011-01-01

    Roč. 96, č. 4 (2011), s. 506-506 ISSN 1097-0282. [ American Peptide Symposium /22./. 25.06.2011-30.06.2011, San Diego] R&D Projects: GA ČR GA203/07/1517; GA MŠk(CZ) LH11033; GA ČR GAP208/11/0105 Grant - others:AV ČR(CZ) M200550902 Institutional research plan: CEZ:AV0Z40550506 Keywords : deferipron * ferric complexes * Raman spectra * DFT study * peptide Subject RIV: CF - Physical ; Theoretical Chemistry

  16. Menaquinone and iron are essential for complex colony development in Bacillus subtilis.

    Directory of Open Access Journals (Sweden)

    Gidi Pelchovich

    Full Text Available Cells of undomesticated species of Bacillus subtilis frequently form complex colonies during spreading on agar surfaces. Given that menaquinone is involved in another form of coordinated behavior, namely, sporulation, we looked for a possible role for menaquinone in complex colony development (CCD in the B. subtilis strain NCIB 3610. Here we show that inhibition of menaquinone biosynthesis in B. subtilis indeed abolished its ability to develop complex colonies. Additionally some mutations of B. subtilis which confer defective CCD could be suppressed by menaquinone derivatives. Several such mutants mapped to the dhb operon encoding the genes responsible for the biosynthesis of the iron siderophore, bacillibactin. Our results demonstrate that both menaquinone and iron are essential for CCD in B. subtilis.

  17. Proton and Electron Additions to Iron (II) Dinitrogen Complexes Containing Pendant Amines

    Energy Technology Data Exchange (ETDEWEB)

    Heiden, Zachariah M.; Chen, Shentan; Labios, Liezel AN; Bullock, R. Morris; Walter, Eric D.; Tyson, Elizabeth L.; Mock, Michael T.

    2014-03-10

    We describe a single site cis-(H)FeII-N2 complex, generated by the protonation of an iron-carbon bond of a "reduced" iron complex, that models key aspects of proposed protonated intermediates of the E4 state of nitrogenase. The influence on N2 binding from the addition of protons to the pendant amine sites in the second coordination sphere is described. Furthermore, the addition of electrons to the protonated complexes results in H2 loss. The mechanism of H2 loss is explored to draw a parallel to the origin of H2 loss (homolytic or heterolytic) and the nature of N2 coordination in intermediates of the E4 state of nitrogenase.

  18. Accurate Computed Enthalpies of Spin Crossover in Iron and Cobalt Complexes

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta; Cirera, J

    2009-01-01

    Despite their importance in many chemical processes, the relative energies of spin states of transition metal complexes have so far been haunted by large computational errors. By the use of six functionals, B3LYP, BP86, TPSS, TPSSh, M06L, and M06L, this work studies nine complexes (seven with iron...... effects of first-row transition metal systems. Furthermore, it is shown that given an experimental structure of an iron complex, TPSSh can predict the electronic state corresponding to that experimental structure. We recommend this functional as current state-of-the-art for studying spin crossover...... and two with cobalt) for which experimental enthalpies of spin crossover are available. It is shown that such enthalpies can be used as quantitative benchmarks of a functional's ability to balance electron correlation in both the involved states. TPSSh achieves an unprecedented mean absolute error...

  19. Synthesis, Physicochemical Properties, and Antimicrobial Studies of Iron (III Complexes of Ciprofloxacin, Cloxacillin, and Amoxicillin

    Directory of Open Access Journals (Sweden)

    Fabian I. Eze

    2014-01-01

    Full Text Available Iron (III complexes of ciprofloxacin, amoxicillin, and cloxacillin were synthesized and their aqueous solubility profiles, relative stabilities, and antimicrobial properties were evaluated. The complexes showed improved aqueous solubility when compared to the corresponding ligands. Relative thermal and acid stabilities were determined spectrophotometrically and the results showed that the complexes have enhanced thermal and acid stabilities when compared to the pure ligands. Antimicrobial studies showed that the complexes have decreased activities against most of the tested microorganisms. Ciprofloxacin complex, however, showed almost the same activity as the corresponding ligand. Job’s method of continuous variation suggested 1 : 2 metals to ligand stoichiometry for ciprofloxacin complex but 1 : 1 for cloxacillin complex.

  20. Congenital deficiency of two polypeptide subunits of the iron-protein fragment of mitochondrial complex I.

    Science.gov (United States)

    Moreadith, R W; Cleeter, M W; Ragan, C I; Batshaw, M L; Lehninger, A L

    1987-02-01

    Recently, we described a patient with severe lactic acidosis due to congenital complex I (NADH-ubiquinone oxidoreductase) deficiency. We now report further enzymatic and immunological characterizations. Both NADH and ferricyanide titrations of complex I activity (measured as NADH-ferricyanide reductase) were distinctly altered in the mitochondria from the patient's tissues. In addition, antisera against complex I immunoprecipitated NADH-ferricyanide reductase from the control but not the patient's mitochondria. However, immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of complex I polypeptides demonstrated that the majority of the 25 polypeptides comprising complex I were present in the affected mitochondria. A more detailed analysis using subunit selective antisera against the main polypeptides of the iron-protein fragments of complex I revealed a selective absence of the 75- and 13-kD polypeptides. These findings suggest that the underlying basis for this patient's disease was a congenital deficiency of at least two polypeptides comprising the iron-protein fragment of complex I, which resulted in the inability to correctly assemble a functional enzyme complex.

  1. Mössbauer effect study of iron(III) inidazolidine nitroxyl-free radical ligand complex

    Science.gov (United States)

    Mulaba, A.; Kiremire, E.; Pollak, H.; Boeyens, J.

    1999-09-01

    A new complex, [Fe(acac)L2], bearing inidazolidine nitroxyl-free radical ligand (L-) was recently synthesised for biological studies. It proved to be biologically active against African sleeping sickness, plasmodium falciparum (malaria), leishmaniasis and chaga disease causative agents. Three ESR well resolved peaks indicated the presence of a free (unpaired) and chemically active electron in the complex. The structural complex ferric iron was found at the centre of two electric gradient whose the biggest is suggested to be initiated by the unpaired charge. No distinction between different cis isomers could be made.

  2. Moessbauer effect study of iron(III)-inidazolidine nitroxyl-free radical ligand complex

    Energy Technology Data Exchange (ETDEWEB)

    Mulaba, A. [Technikon Witwatersrand, Metallurgy Department (South Africa); Kiremire, E. [University of the Witwatersrand, Chemistry Department (South Africa); Pollak, H. [University of the Witwatersrand, Physics Department (South Africa); Boeyens, J. [University of the Witwatersrand, Chemistry Department (South Africa)

    1999-09-15

    A new complex, [Fe(acac)L{sub 2}], bearing inidazolidine nitroxyl-free radical ligand (L{sup -}) was recently synthesised for biological studies. It proved to be biologically active against African sleeping sickness, plasmodium falciparum (malaria), leishmaniasis and chaga disease causative agents. Three ESR well resolved peaks indicated the presence of a free (unpaired) and chemically active electron in the complex. The structural complex ferric iron was found at the centre of two electric gradient whose the biggest is suggested to be initiated by the unpaired charge. No distinction between different cis isomers could be made.

  3. Nickel and iron pincer complexes as catalysts for the reduction of carbonyl compounds.

    Science.gov (United States)

    Chakraborty, Sumit; Bhattacharya, Papri; Dai, Huiguang; Guan, Hairong

    2015-07-21

    The reductions of aldehydes, ketones, and esters to alcohols are important processes for the synthesis of chemicals that are vital to our daily life, and the reduction of CO2 to methanol is expected to provide key technology for carbon management and energy storage in our future. Catalysts that affect the reduction of carbonyl compounds often contain ruthenium, osmium, or other precious metals. The high and fluctuating price, and the limited availability of these metals, calls for efforts to develop catalysts based on more abundant and less expensive first-row transition metals, such as nickel and iron. The challenge, however, is to identify ligand systems that can increase the thermal stability of the catalysts, enhance their reactivity, and bypass the one-electron pathways that are commonly observed for first-row transition metal complexes. Although many other strategies exist, this Account describes how we have utilized pincer ligands along with other ancillary ligands to accomplish these goals. The bis(phosphinite)-based pincer ligands (also known as POCOP-pincer ligands) create well-defined nickel hydride complexes as efficient catalysts for the hydrosilylation of aldehydes and ketones and the hydroboration of CO2 to methanol derivatives. The hydride ligands in these complexes are substantially nucleophilic, largely due to the enhancement by the strongly trans-influencing aryl groups. Under the same principle, the pincer-ligated nickel cyanomethyl complexes exhibit remarkably high activity (turnover numbers up to 82,000) for catalytically activating acetonitrile and the addition of H-CH2CN across the C═O bonds of aldehydes without requiring a base additive. Cyclometalation of bis(phosphinite)-based pincer ligands with low-valent iron species "Fe(PR3)4" results in diamagnetic Fe(II) hydride complexes, which are active catalysts for the hydrosilylation of aldehydes and ketones. Mechanistic investigation suggests that the hydride ligand is not delivered to the

  4. The F'derik-Zouerate iron district: Mesoarchean and Paleoproterozoic iron formation of the Tiris Complex, Islamic Republic of Mauritania

    Science.gov (United States)

    Taylor, Cliff D.; Finn, Carol A.; Anderson, Eric D.; Bradley, Dwight C.; Joud, Mohamed; Taleb Mohamed, Ahmed; Horton, John D.; Johnson, Craig A.; Bouabdellah, Mohammed; Slack, John F.

    2016-01-01

    High-grade hematitic iron ores (of HIF, containing 60-65 wt%Fe) have been mined in Mauritania since 1952 from Superior-type iron deposits of the F'derik-Zouerate district.  Depletion of the high-grade ores in recent years has resulted in new exploration projects focused on lower-grade magnetite ores occurring in Algoma-type banded iron formation (of BIF, containing ca. 35 wt% Fe).  Mauritania is the seventeenth largest iron producer in the world and currently has about 1.1 Gt of crude iron ore reserves. 

  5. Stability of tris-1,10-phenanthroline iron (II) complex in biomineral particles produced by Klebsiella oxytoca

    International Nuclear Information System (INIS)

    Anghel, L.V.; Balasoiu, M.; Lazar, D.M.; Ishchenko, L.A.

    2011-01-01

    The composition of composites has a huge impact on the stability of tris-1,10-phenanthroline iron (II) complex during the determination of total iron content. The subject of this work is the determination of the stability of tris-1,10-phenanthroline iron (II) complex in samples of biominerals produced by bacteria Klebsiella oxytoca. The stability of this complex was monitored in the time period of 0-60 min. The aim of this work is to determine the concentration of the biogenic ferrihydrite in the samples and the time interval in which the absorbance of the complex is highest. The UV-Vis spectrophotometric method was used for the determination. Obtained results indicate that for more exact estimations of the concentration of biogenic ferrihydrite, absorbance of tris-1,10-phenanthroline iron (II) complex should be measured within 25 min from the moment ortho-phenanthroline was added

  6. Bifunctional (cyclopentadienone)iron-tricarbonyl complexes: Synthesis, computational studies and application in reductive amination

    KAUST Repository

    Moulin, Solenne

    2013-11-15

    Reductive amination under hydrogen pressure is a valuable process in organic chemistry to access amine derivatives from aldehydes or ketones. Knölker\\'s complex has been shown to be an efficient iron catalyst in this reaction. To determine the influence of the substituents on the cyclopentadienone ancillary ligand, a series of modified Knölker\\'s complexes was synthesised and fully characterised. These complexes were also transformed into their analogous acetonitrile iron-dicarbonyl complexes. Catalytic activities of these complexes were evaluated and compared in a model reaction. The scope of this reaction is also reported. For mechanistic insights, deuterium-labelling experiments and DFT calculations were undertaken and are also presented. Festival of amination: Two series of modified Knölker\\'s complexes were synthesised and applied in the reductive amination of various carbonyl derivatives with primary or secondary amines (see scheme, TIPS = triisopropylsilyl). For a mechanistic insight, deuterium-labelling experiments and DFT calculations were undertaken and are also presented. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Depressing Iron Mineral by Metallic-Starch Complex (MSC in Reverse Flotation and Its Mechanism

    Directory of Open Access Journals (Sweden)

    Tao Yue

    2018-02-01

    Full Text Available A series of metallic-starch complex (MSC solutions, synthesized by mixing relevant metallic ionic solutions with the caustic starch solution, were used as the flotation depressants to investigate their depressing effects on hematite ore. The MSC is a nano-sized colloidal complex which is configured by hydrophilic metallic hydroxide as the colloidal nucleus on which starch and hydroxyl complex are adsorbed, resulting in a larger molecule than starch itself. The flotation tests showed that the depressing abilities of various MSC (Fe3+, Zn2+, Pb2+ and Mg2+ on the iron minerals were higher than the caustic starch, and the order of depression ability was: Zn2+-starch > Pb2+-starch > Fe3+-starch > Mg2+-starch > caustic starch. Based on the adsorption analysis, the high depressing ability of the MSC arose from increasing the adsorption density of starch on iron minerals and slightly reducing the absorption of the collector dodecylamine. Adsorption behaviour also indicated that the adsorption of the MSC on mineral surfaces was thicker than the caustic starch, and among various MSC the adsorption of Fe3+-starch exhibited the thickest adsorption layer while that of Mg2+-starch the thinnest. Zeta potential indicated that with a weaker electronegativity than the caustic starch, MSC adsorbed onto iron minerals more easily, and the strong electrostatic adsorption with the aid of the hydrogen bonding and chemisorption agreed well with the high depressing ability of the MSC.

  8. Fast analysis of transferrin-iron complexes using isoelectric focusing and in situ radioactive densitometry

    International Nuclear Information System (INIS)

    Legendre, J.M.; Moineau, M.P.; Turzo, A.; Menez, J.F.

    1985-01-01

    The analysis of the molecular forms of transferrin-iron complexes with 59 Fe, was carried out using an isoelectric focusing method on commercially available polyacrylamide plates (PAG plates pH=4-6,5, LKB). Depending upon the saturation degree of proteins with iron, apotransferrin (pI=6,1), transferrin-Fe 3+ (pI=5,8), transferrin-2 Fe 3+ (a) (pI=5,5) and transferrin-2 Fe 3+ (b) (pI=5,3) were put forward. When the protein was saturated with iron, a double band was observed which was assigned to the microheterogeneity of the protein and depends upon the sialic content. The quantitative analysis was carried out by studying 59 Fe radioactivity distribution directly on the plate. As a control, a specific staining of proteins was achieved. The interpretation of the results is difficult if such a method is used, as some bands are not attributed. Through an unspecific staining, the UV-visible densitometry is not satisfactory enough. The proposed method allows a fast analysis of transferring-metal complexes labeled with radioactive metals. Such a method would be adaptable to the study of other complexes as transferrin- 67 Ga, transferrin 111 In in order to determine the binding site of metal on the protein and its metal content [fr

  9. Synthesis, Characterization and Spectral Properties of Substituted Tetraphenylporphyrin Iron Chloride Complexes

    Directory of Open Access Journals (Sweden)

    Kai Li

    2011-04-01

    Full Text Available A series of substituted tetraphenylporphyrin iron chloride complexes [RTPPFe(IIICl, R=o/p-NO2, o/p-Cl, H, o/p-CH3, o/p-OCH3] were synthesized by a novel universal mixed-solvent method and the spectral properties of free base porphyrins and iron porphyrin compounds were compared with each other. The experimental results showed that the one-pot mixed solvent method was superior to the two-step method in the yields, reaction time and workup of reaction mixtures for the synthesis of iron porphyrin compounds. The highest yields (28.7%-40.4% of RTPPFe(IIICl were obtained in the mixed solvents propionic acid, glacial acetic acid and m-nitrotoluene under reflux for 2 h. A detailed analysis of ultraviolet-visible (UV-vis, infrared (IR and far-infrared (FIR spectra suggested the transformation from free base porphyrins to iron porphyrins. The red shift of the Soret band in ultraviolet-visible spectra due to the presence of p-nitrophenyl substituents and the blue shift of Fe-Cl bond of TPPFeCl in far-infrared spectra were further explained by the electron transfer and molecular planarity in the porphyrin ring.

  10. Dinitrosyl non-heme iron complexes at the gamma radiation treatment of animals

    International Nuclear Information System (INIS)

    Aliev, D.I.; Alieva, I.N.; Abilov, Z.G.; Gurbanov, I.S.

    2003-01-01

    Full text: At the present time there are a great number investigations dedicated to revealing of mechanism formation of 2,03 complexes at the some pathologies in an organism. These complexes are represented weakly bounded form of non-heme iron, including into beside iron two nitrogen oxide molecules (NO) and two paired RS- groups of proteins or low-molecular compounds. 2,03 complexes are characterized by an axial symmetrical tensory of the g-factor with g=2,037, g=2,012 and g=2,03. In this study the data testifying 2,03 complexes formation into liver of animal treated by the fatal dose of gamma-radiation are reported. The changing of the ESR signal form was observed. It was shown that the form and intensity of the 2,03 signal in healthy and irradiated animals are differ from each other. The analysis of the 2,03 signal parameters is confirm this fact, too. The conclusion was made that 2,03 complexes ESR signal may be considered as an indicator of integrity of intracellular membranes of the gamma-irradiated animals

  11. Alternating ring-opening copolymerization of cyclohexene oxide with phthalic anhydride catalyzed by iron(III) salen complexes

    Czech Academy of Sciences Publication Activity Database

    Mundil, R.; Hošťálek, Z.; Šeděnková, Ivana; Merna, J.

    2015-01-01

    Roč. 23, č. 2 (2015), s. 161-166 ISSN 1598-5032 Institutional support: RVO:61389013 Keywords : polyesters * iron salen complexes * catalysis Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.357, year: 2015

  12. Application of complex inoculants in improving the process-ability of grey cast iron for cylinder blocks

    Directory of Open Access Journals (Sweden)

    LIU Wei-ming

    2006-05-01

    Full Text Available Effect of several complex inoculants on mechanical properties, process-ability and sensibility of grey cast iron used in cylinder block were investigated. The experimental results showed that the grey cast iron treated with 60%FeSi75+40%RE complex inoculants has tensile strength consistently at about 295 MPa along with good hardness and improved metallurgy quality. While the grey cast iron inoculated with 20%FeSi75+80%Sr compound inoculants has the best process-ability, the lowest cross-section sensibility and the least microhardness difference. The wear amount of the drill increases correspondingly with the increase of the microhardness difference of matrix structure, indicating the great effect of homogeneousness of matrix structure in the grey cast iron on the machinability of the grey cast iron.

  13. Photodegradation of orange I in the heterogeneous iron oxide-oxalate complex system under UVA irradiation

    International Nuclear Information System (INIS)

    Lei, Jing; Liu Chengshuai; Li Fangbai; Li Xiaomin; Zhou Shungui; Liu Tongxu; Gu Minghua; Wu Qitang

    2006-01-01

    To understand the photodegradation of azo dyes in natural aquatic environment, a novel photo-Fenton-like system, the heterogeneous iron oxide-oxalate complex system was set up with the existence of iron oxides and oxalate. Five iron oxides, including γ-FeOOH, IO-250, IO-320, IO-420 and IO-520, were prepared and their adsorption capacity was investigated in the dark. The results showed that the saturated adsorption amount (Γ max ) was ranked the order of IO-250>IO-320>γ-FeOOH>IO-420>IO-520 and the adsorption equilibrium constant (K a ) followed the order of IO-250>IO-520>γ-FeOOH>IO-420>IO-320. The effect of initial pH value, the initial concentrations of oxalate and orange I on the photodegradation of orange I were also investigated in different iron oxide-oxalate systems. The results showed that the photodegradation of orange I under UVA irradiation could be enhanced greatly in the presence of oxalate. And the optimal oxalate concentrations (C ox 0 ) for γ-FeOOH, IO-250, IO-320, IO-420 and IO-520 were 1.8, 1.6, 3.5, 3.0 and 0.8mM, respectively. The photodegradation of orange I in the presence of optimal C ox 0 was ranked as the order of γ-FeOOH>IO-250>IO-320>IO-420>IO-520. The optimal range of initial pH was at about 3-4. The first-order kinetic constant for the degradation of orange I decreased with the increase in the initial concentration of orange I. Furthermore, the variation of pH, the concentrations of Fe 3+ and Fe 2+ during the photoreaction were also strongly dependent on the C ox 0 and iron oxides

  14. Effect of tris(3-hydroxy-4-pyridinonate) iron(III) complexes on iron uptake and storage in soybean (Glycine max L.).

    Science.gov (United States)

    Santos, Carla S; Carvalho, Susana M P; Leite, Andreia; Moniz, Tânia; Roriz, Mariana; Rangel, António O S S; Rangel, Maria; Vasconcelos, Marta W

    2016-09-01

    Iron deficiency chlorosis (IDC) is a serious environmental problem affecting the growth of several crops in the world. The application of synthetic Fe(III) chelates is still one of the most common measures to correct IDC and the search for more effective Fe chelates remains an important issue. Herein, we propose a tris(3-hydroxy-4-pyridinonate) iron(III) complex, Fe(mpp)3, as an IDC corrector. Different morphological, biochemical and molecular parameters were assessed as a first step towards understanding its mode of action, compared with that of the commercial fertilizer FeEDDHA. Plants treated with the pyridinone iron(III) complexes were significantly greener and had increased biomass. The total Fe content was measured using ICP-OES and plants treated with pyridinone complexes accumulated about 50% more Fe than those treated with the commercial chelate. In particular, plants supplied with compound Fe(mpp)3 were able to translocate iron from the roots to the shoots and did not elicit the expression of the Fe-stress related genes FRO2 and IRT1. These results suggest that 3,4-HPO iron(III) chelates could be a potential new class of plant fertilizing agents. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  15. Highly Efficient Hydrogenation of Levulinic Acid into γ-Valerolactone with an Iron Pincer Complex.

    Science.gov (United States)

    Yi, Yuxuan; Liu, Huiying; Xiao, Ling-Ping; Wang, Bo; Song, Guoyong

    2018-03-25

    The search for nonprecious metal catalysts for the synthesis of γ-valerolactone (GVL) through hydrogenation of levulinic acid and its derivative in an efficient fashion is of great interest and importance, as GVL is an important a sustainable liquid. We herein report a pincer iron complex can efficiently catalyze the hydrogenation of levulinic acid and methyl levulinate into GVL, achieved up to 23000 turnover numbers and 1917 h-1 turnover frequencies. This iron catalyst also enabled the formation of GVL from various biomass-derived carbohydrates in aqueous solution, thus paving a new way toward a renewable chemical industry. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Li4FeH6: Iron-containing complex hydride with high gravimetric hydrogen density

    Directory of Open Access Journals (Sweden)

    Hiroyuki Saitoh

    2014-07-01

    Full Text Available Li4FeH6, which has the highest gravimetric hydrogen density of iron-containing complex hydrides reported so far, is synthesized by hydrogenation of a powder mixture of iron and LiH above 6.1 GPa at 900 °C. In situ synchrotron radiation X-ray diffraction measurements reveal that while kinetics require high temperature and thus high pressure for the synthesis, Li4FeH6 is expected to be thermodynamically stable slightly below room temperature at ambient pressure; further synthetic studies to suppress the kinetic effects may enable us to synthesize Li4FeH6 at moderate pressures. Li4FeH6 can be recovered at ambient conditions where Li4FeH6 is metastable.

  17. Ethylene oligomerization using iron complexes: beyond the discovery of bis(imino)pyridine ligands.

    Science.gov (United States)

    Boudier, Adrien; Breuil, Pierre-Alain R; Magna, Lionel; Olivier-Bourbigou, Hélène; Braunstein, Pierre

    2014-02-11

    Since the discovery that bis(imino)pyridine ligands are able to confer high activities in ethylene oligomerization and polymerization to their iron complexes, considerable attention has been focused on catalyst design for these reactions and this research constitutes an ever-growing area in molecular catalysis. The tuning of the ligand structures and properties, and thus of catalysts, generally represents the basis for subsequent work contributing to process development and industrialization. Significant effort is therefore devoted to generate structural diversity in order to access the required catalyst stability and selectivity. This feature article outlines nitrogen-containing ligands that have been developed for the iron-catalyzed oligomerization of ethylene since the seminal discovery of the properties of bis(imino)pyridine ligands.

  18. Synthesis and characterization of an iron complex bearing a cyclic tetra-N-heterocyclic carbene ligand: An artifical heme analogue?

    KAUST Repository

    Anneser, Markus R.

    2015-04-20

    An iron(II) complex with a cyclic tetradentate ligand containing four N-heterocyclic carbenes was synthesized and characterized by means of NMR and IR spectroscopies, as well as by single-crystal X-ray structure analysis. The iron center exhibits an octahedral coordination geometry with two acetonitrile ligands in axial positions, showing structural analogies with porphyrine-ligated iron complexes. The acetonitrile ligands can readily be substituted by other ligands, for instance, dimethyl sulfoxide, carbon monoxide, and nitric oxide. Cyclic voltammetry was used to examine the electronic properties of the synthesized compounds. © 2015 American Chemical Society.

  19. Synthesis, spectroscopy, and hydrogen/deuterium exchange in high-spin iron(II) hydride complexes.

    Science.gov (United States)

    Dugan, Thomas R; Bill, Eckhard; MacLeod, K Cory; Brennessel, William W; Holland, Patrick L

    2014-03-03

    Very few hydride complexes are known in which the metals have a high-spin electronic configuration. We describe the characterization of several high-spin iron(II) hydride/deuteride isotopologues and their exchange reactions with one another and with H2/D2. Though the hydride/deuteride signal is not observable in NMR spectra, the choice of isotope has an influence on the chemical shifts of distant protons in the dimers through the paramagnetic isotope effect on chemical shift. This provides the first way to monitor the exchange of H and D in the bridging positions of these hydride complexes. The rate of exchange depends on the size of the supporting ligand, and this is consistent with the idea that H2/D2 exchange into the hydrides occurs through the dimeric complexes rather than through a transient monomer. The understanding of H/D exchange mechanisms in these high-spin iron hydride complexes may be relevant to postulated nitrogenase mechanisms.

  20. Tracking excited-state charge and spin dynamics in iron coordination complexes

    DEFF Research Database (Denmark)

    Zhang, Wenkai; Alonso-Mori, Roberto; Bergmann, Uwe

    2014-01-01

    to spin state, can elucidate the spin crossover dynamics of [Fe(2,2'-bipyridine)(3)](2+) on photoinduced metal-to-ligand charge transfer excitation. We are able to track the charge and spin dynamics, and establish the critical role of intermediate spin states in the crossover mechanism. We anticipate......Crucial to many light-driven processes in transition metal complexes is the absorption and dissipation of energy by 3d electrons(1-4). But a detailed understanding of such non-equilibrium excited-state dynamics and their interplay with structural changes is challenging: a multitude of excited...... states and possible transitions result in phenomena too complex to unravel when faced with the indirect sensitivity of optical spectroscopy to spin dynamics(5) and the flux limitations of ultrafast X-ray sources(6,7). Such a situation exists for archetypal poly-pyridyl iron complexes, such as [Fe(2...

  1. Nitric oxide synthase (NOS inhibition during porcine in vitro maturation modifies oocyte protein S-nitrosylation and in vitro fertilization.

    Directory of Open Access Journals (Sweden)

    Jon Romero-Aguirregomezcorta

    Full Text Available Nitric oxide (NO is a molecule involved in many reproductive processes. Its importance during oocyte in vitro maturation (IVM has been demonstrated in various species although sometimes with contradictory results. The objective of this study was to determine the effect of NO during IVM of cumulus oocyte complexes and its subsequent impact on gamete interaction in porcine species. For this purpose, IVM media were supplemented with three NOS inhibitors: NG-nitro-L-arginine methyl ester (L-NAME, NG-monomethyl-L-arginine (L-NMMA and aminoguanidine (AG. A NO donor, S-nitrosoglutathione (GSNO, was also used. The effects on the cumulus cell expansion, meiotic resumption, zona pellucida digestion time (ZPdt and, finally, on in vitro fertilization (IVF parameters were evaluated. The oocyte S-nitrosoproteins were also studied by in situ nitrosylation. The results showed that after 42 h of IVM, AG, L-NAME and L-NMMA had an inhibitory effect on cumulus cell expansion. Meiotic resumption was suppressed only when AG was added, with 78.7% of the oocytes arrested at the germinal vesicle state (P<0.05. Supplementation of the IVM medium with NOS inhibitors or NO donor did not enhance the efficiency of IVF, but revealed the importance of NO in maturation and subsequent fertilization. Furthermore, protein S-nitrosylation is reported for the first time as a pathway through which NO exerts its effect on porcine IVM; therefore, it would be important to determine which proteins are nitrosylated in the oocyte and their functions, in order to throw light on the mechanism of action of NO in oocyte maturation and subsequent fertilization.

  2. Prevention of Acid Mine Drainage Through Complexation of Ferric Iron by Soluble Microbial Growth Products

    Science.gov (United States)

    Pandey, S.; Yacob, T. W.; Silverstein, J.; Rajaram, H.; Minchow, K.; Basta, J.

    2011-12-01

    Acid mine drainage (AMD) is a widespread environmental problem with deleterious impacts on water quality in streams and watersheds. AMD is generated largely by the oxidation of metal sulfides (i.e. pyrite) by ferric iron. This abiotic reaction is catalyzed by conversion of ferrous to ferric iron by iron and sulfur oxidizing microorganisms. Biostimulation is currently being investigated as an attempt to inhibit the oxidation of pyrite and growth of iron oxidizing bacteria through addition of organic carbon. This may stimulate growth of indigenous communities of acidophilic heterotrophic bacteria to compete for oxygen. The goal of this research is to investigate a secondary mechanism associated with carbon addition: complexation of free Fe(III) by soluble microbial growth products (SMPs) produced by microorganisms growing in waste rock. Exploratory research at the laboratory scale examined the effect of soluble microbial products (SMPs) on the kinetics of oxidation of pure pyrite during shaker flask experiments. The results confirmed a decrease in the rate of pyrite oxidation that was dependent upon the concentration of SMPs in solution. We are using these data to verify results from a pyrite oxidation model that accounts for SMPs. This reactor model involves differential-algebraic equations incorporating total component mass balances and mass action laws for equilibrium reactions. Species concentrations determined in each time step are applied to abiotic pyrite oxidation rate expressions from the literature to determine the evolution of total component concentrations. The model was embedded in a parameter estimation algorithm to determine the reactive surface area of pyrite in an abiotic control experiment, yielding an optimized value of 0.0037 m2. The optimized model exhibited similar behavior to the experiment for this case; the root mean squared of residuals for Fe(III) was calculated to be 7.58 x 10-4 M, which is several orders of magnitude less than the actual

  3. The Rieske Iron-Sulfur Protein: Import and Assembly into the Cytochrome bc 1 Complex of Yeast Mitochondria

    Science.gov (United States)

    Conte, Laura; Zara, Vincenzo

    2011-01-01

    The Rieske iron-sulfur protein, one of the catalytic subunits of the cytochrome bc 1 complex, is involved in electron transfer at the level of the inner membrane of yeast mitochondria. The Rieske iron-sulfur protein is encoded by nuclear DNA and, after being synthesized in the cytosol, is imported into mitochondria with the help of a cleavable N-terminal presequence. The imported protein, besides incorporating the 2Fe-2S cluster, also interacts with other catalytic and non-catalytic subunits of the cytochrome bc 1 complex, thereby assembling into the mature and functional respiratory complex. In this paper, we summarize the most recent findings on the import and assembly of the Rieske iron-sulfur protein into Saccharomyces cerevisiae mitochondria, also discussing a possible role of this protein both in the dimerization of the cytochrome bc 1 complex and in the interaction of this homodimer with other complexes of the mitochondrial respiratory chain. PMID:21716720

  4. The Rieske Iron-Sulfur Protein: Import and Assembly into the Cytochrome bc(1) Complex of Yeast Mitochondria.

    Science.gov (United States)

    Conte, Laura; Zara, Vincenzo

    2011-01-01

    The Rieske iron-sulfur protein, one of the catalytic subunits of the cytochrome bc(1) complex, is involved in electron transfer at the level of the inner membrane of yeast mitochondria. The Rieske iron-sulfur protein is encoded by nuclear DNA and, after being synthesized in the cytosol, is imported into mitochondria with the help of a cleavable N-terminal presequence. The imported protein, besides incorporating the 2Fe-2S cluster, also interacts with other catalytic and non-catalytic subunits of the cytochrome bc(1) complex, thereby assembling into the mature and functional respiratory complex. In this paper, we summarize the most recent findings on the import and assembly of the Rieske iron-sulfur protein into Saccharomyces cerevisiae mitochondria, also discussing a possible role of this protein both in the dimerization of the cytochrome bc(1) complex and in the interaction of this homodimer with other complexes of the mitochondrial respiratory chain.

  5. Phenol Nitration Induced by an {Fe(NO)2}10 Dinitrosyl Iron Complex

    Energy Technology Data Exchange (ETDEWEB)

    N Tran; H Kalyvas; K Skodje; T Hayashi; P Moenne-Loccoz; P Callan; J Shearer; L Kirschenbaum; E Kim

    2011-12-31

    Cellular dinitrosyl iron complexes (DNICs) have long been considered NO carriers. Although other physiological roles of DNICs have been postulated, their chemical functionality outside of NO transfer has not been demonstrated thus far. Here we report the unprecedented dioxygen reactivity of a N-bound {l_brace}Fe(NO){sub 2}{r_brace}{sup 10} DNIC, [Fe(TMEDA)(NO){sub 2}] (1). In the presence of O{sub 2}, 1 becomes a nitrating agent that converts 2,4,-di-tert-butylphenol to 2,4-di-tert-butyl-6-nitrophenol via formation of a putative iron-peroxynitrite [Fe(TMEDA)(NO)(ONOO)] (2) that is stable below -80 C. Iron K-edge X-ray absorption spectroscopy on 2 supports a five-coordinated metal center with a bound peroxynitrite in a cyclic bidentate fashion. The peroxynitrite ligand of 2 readily decays at increased temperature or under illumination. These results suggest that DNICs could have multiple physiological or deleterious roles, including that of cellular nitrating agents.

  6. Synthesis, structures, and dearomatization by deprotonation of iron complexes featuring bipyridine-based PNN pincer ligands.

    Science.gov (United States)

    Zell, Thomas; Langer, Robert; Iron, Mark A; Konstantinovski, Leonid; Shimon, Linda J W; Diskin-Posner, Yael; Leitus, Gregory; Balaraman, Ekambaram; Ben-David, Yehoshoa; Milstein, David

    2013-08-19

    The synthesis and characterization of new iron pincer complexes bearing bipyridine-based PNN ligands is reported. Three phosphine-substituted pincer ligands, namely, the known (t)Bu-PNN (6-((di-tert-butylphosphino)methyl)-2,2'-bipyridine) and the two new (i)Pr-PNN (6-((di-iso-propylphosphino)methyl)-2,2'-bipyridine) and Ph-PNN (6-((diphenylphosphino)methyl)-2,2'-bipyridine) ligands were synthesized and studied in ligation reactions with iron(II) chloride and bromide. These reactions lead to the formation of two types of complexes: mono-chelated neutral complexes of the type [(R-PNN)Fe(X)2] and bis-chelated dicationic complexes of the type [(R-PNN)2Fe](2+). The complexes [(R-PNN)Fe(X)2] (1: R = (t)Bu, X = Cl, 2: R = (t)Bu, X = Br, 3: R = (i)Pr, X = Cl, and 4: R = (i)Pr, X = Br) are readily prepared from reactions of FeX2 with the free R-PNN ligand in a 1:1 ratio. Magnetic susceptibility measurements show that these complexes have a high-spin ground state (S = 2) at room temperature. Employing a 2-fold or higher excess of (i)Pr-PNN, diamagnetic hexacoordinated dicationic complexes of the type [((i)Pr-PNN)2Fe](X)2 (5: X = Cl, and 6: X = Br) are formed. The reactions of Ph-PNN with FeX2 in a 1:1 ratio lead to similar complexes of the type [(Ph-PNN)2Fe](FeX4) (7: X = Cl, and 8: X = Br). Single crystal X-ray studies of 1, 2, 4, 6, and 8 do not indicate electron transfer from the Fe(II) centers to the neutral bipyridine unit based on the determined bond lengths. Density functional theory (DFT) calculations were performed to compare the relative energies of the mono- and bis-chelated complexes. The doubly deprotonated complexes [(R-PNN*)2Fe] (9: R = (i)Pr, and 10: R = Ph) were synthesized by reactions of the dicationic complexes 6 and 8 with KO(t)Bu. The dearomatized nature of the central pyridine of the pincer ligand was established by X-ray diffraction analysis of single crystals of 10. Reactivity studies show that 9 and 10 have a slightly different behavior in

  7. Economic interdependence and complexity: Falaj agriculture and ceramic production in the southeast Arabian iron age

    International Nuclear Information System (INIS)

    Magee, P.

    1997-01-01

    Over the last fifteen years surveys and excavations in the United Arab Emirates and Sultanate of Oman have revealed a widespread and distinctive material culture dating to the late second and first millennium BC. In this paper the results of PIXE-PIGME analysis of ceramics from the Iron II period (1100-600 BC) are presented. In combination with ceramic distribution data, the analysis permits the identification of ceramic production areas. More importantly, however, the analysis, when combined with environmental and subsistence strategy data, provides an insight into the relationship between agricultural intensification and ceramic production and the varying degrees of economic complexity which existed at this time

  8. Manipulating charge transfer excited state relaxation and spin crossover in iron coordination complexes with ligand substitution

    DEFF Research Database (Denmark)

    Zhang, Wenkai; Kjær, Kasper Skov; Alonso-Mori, Roberto

    2017-01-01

    iron complexes with four cyanide (CN-;) ligands and one 2,2′-bipyridine (bpy) ligand. This enables MLCT excited state and metal-centered excited state energies to be manipulated with partial independence and provides a path to suppressing spin crossover. We have combined X-ray Free-Electron Laser (XFEL......) Kβ hard X-ray fluorescence spectroscopy with femtosecond time-resolved UV-visible absorption spectroscopy to characterize the electronic excited state dynamics initiated by MLCT excitation of [Fe(CN)4(bpy)]2-. The two experimental techniques are highly complementary; the time-resolved UV...

  9. Dynamin2 S-nitrosylation regulates adenovirus type 5 infection of epithelial cells.

    Science.gov (United States)

    Wang, Zhimin; Kim, Jae Il; Frilot, Nicole; Daaka, Yehia

    2012-10-01

    Dynamin2 is a large GTPase that regulates vesicle trafficking, and the GTPase activity of dynamin2 is required for the multistep process of adenovirus infection. Activity of dynamin2 may be regulated by post-translational phosphorylation and S-nitrosylation modifications. In this study, we demonstrate a role for dynamin2 S-nitrosylation in adenovirus infection of epithelial cells. We show that adenovirus serotype 5 (Ad5) infection augments production of nitric oxide (NO) in epithelial cells and causes the S-nitrosylation of dynamin2, mainly on cysteine 86 (C86) and 607 (C607) residues. Forced overexpression of dynamin2 bearing C86A and/or C607A mutations decreases Ad5 infection. Diminishing NO synthesis by RNAi-induced knockdown of endogenous endothelial NO synthase (eNOS) expression attenuates virus infection of target cells. Ad5 infection promotes the kinetically dynamic S-nitrosylation of dynamin2 and eNOS: there is a rapid decrease in eNOS S-nitrosylation and a concomitant increase in the dynamin2 S-nitrosylation. These results support the hypothesis that dynamin2 S-nitrosylation following eNOS activation facilitates adenovirus infection of host epithelial cells.

  10. First success of catalytic epoxidation of olefins by an electron-rich iron(III) porphyrin complex and H2O2: imidazole effect on the activation of H2O2 by iron porphyrin complexes in aprotic solvent.

    Science.gov (United States)

    Nam, W; Lee, H J; Oh, S Y; Kim, C; Jang, H G

    2000-07-01

    An electron-rich iron(III) porphyrin complex (meso-tetramesitylporphinato)iron(III) chloride [Fe(TMP)Cl], was found to catalyze the epoxidation of olefins by aqueous 30% H2O2 when the reaction was carried out in the presence of 5-chloro-1-methylimidazole (5-Cl-1-Melm) in aprotic solvent. Epoxides were the predominant products with trace amounts of allylic oxidation products, indicating that Fenton-type oxidation reactions were not involved in the olefin epoxidation reactions. cis-Stilbene was stereospecifically oxidized to cis-stilbene oxide without giving isomerized trans-stilbene oxide product, demonstrating that neither hydroperoxy radical (HOO*) nor oxoiron(IV) porphyrin [(TMP)FeIV=O] was responsible for the olefin epoxidations. We also found that the reactivities of other iron(III) porphyrin complexes such as (meso-tetrakis(2,6-dichlorophenyl)porphinato)iron(III) chloride [Fe(TDCPP)Cl], (meso-tetrakis(2,6-difluorophenyl)porphinato)iron(III) chloride [Fe(TDFPP)Cl], and (meso-tetrakis(pentafluorophenyl)porphinato)iron(III) chloride [Fe(TPFPP)CI] were significantly affected by the presence of the imidazole in the epoxidation of olefins by H2O2. These iron porphyrin complexes did not yield cyclohexene oxide in the epoxidation of cyclohexene by H2O2 in the absence of 5-Cl-1-MeIm in aprotic solvent; however, addition of 5-Cl-1-MeIm to the reaction solutions gave high yields of cyclohexene oxide with the formation of trace amounts of allylic oxidation products. We proposed, on the basis of the results of mechanistic studies, that the role of the imidazole is to decelerate the O-O bond cleavage of an iron(III) hydroperoxide porphyrin (or H2O2-iron(II) porphyrin adduct) and that the intermediate transfers its oxygen to olefins prior to the O-O bond cleavage.

  11. Hydrogenation of Carbon Dioxide to Methanol Catalyzed by Iron, Cobalt, and Manganese Cyclopentadienone Complexes: Mechanistic Insights and Computational Design.

    Science.gov (United States)

    Ge, Hongyu; Chen, Xiangyang; Yang, Xinzheng

    2017-07-03

    Density functional theory study of the hydrogenation of carbon dioxide to methanol catalyzed by iron, cobalt, and manganese cyclopentadienone complexes reveals a self-promoted mechanism, which features a methanol- or water-molecule-assisted proton transfer for the cleavage of H 2 . The total free energy barrier of the formation of methanol from CO 2 and H 2 catalyzed by Knölker's iron cyclopentadienone complex, [2,5-(SiMe 3 ) 2 -3,4-(CH 2 ) 4 (η 5 -C 4 COH)]Fe(CO) 2 H, is 26.0 kcal mol -1 in the methanol solvent. We also evaluated the catalytic activities of 8 other experimentally reported iron cyclopentadienone complexes and 37 iron, cobalt, and manganese cyclopentadienone complexes proposed in this study. In general, iron and manganese complexes have relatively higher catalytic activities. Among all calculated complexes, [2,5-(SiMe 3 ) 2 -3,4-CH 3 CHSCH 2 (η 5 -C 4 COH)]Fe(CO) 2 H (1 Fe-Casey-S-CH3 ) is the most active one with a total free energy barrier of 25.1 kcal mol -1 in the methanol solvent. Such a low barrier indicates that 1 Fe-Casey-S-CH3 is a very promising low-cost and high efficiency catalyst for the conversion of CO 2 and H 2 to methanol under mild conditions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Spin-State-Controlled Photodissociation of Iron(III) Azide to an Iron(V) Nitride Complex

    Czech Academy of Sciences Publication Activity Database

    Andris, E.; Navrátil, R.; Jašík, J.; Sabenya, G.; Costas, M.; Srnec, Martin; Roithová, J.

    2017-01-01

    Roč. 56, č. 45 (2017), s. 14057-14060 ISSN 1521-3773 Institutional support: RVO:61388955 Keywords : Ion spectroscopy * Iron (V) nitride * Photodissociation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  13. Spin-State-Controlled Photodissociation of Iron(III) Azide to an Iron(V) Nitride Complex

    Czech Academy of Sciences Publication Activity Database

    Andris, E.; Navrátil, R.; Jašík, J.; Sabenya, G.; Costas, M.; Srnec, Martin; Roithová, J.

    2017-01-01

    Roč. 56, č. 45 (2017), s. 14057-14060 ISSN 1521-3773 Institutional support: RVO:61388955 Keywords : Ion spectroscopy * Iron(V) nitride * Photodissociation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

  14. Proteomic analysis of S-nitrosylated proteins in Arabidopsis thaliana undergoing hypersensitive response

    DEFF Research Database (Denmark)

    Romero-Puertas, Maria C; Campostrini, Natascia; Mattè, Alessandro

    2008-01-01

    Nitric oxide (NO) has a fundamental role in the plant hypersensitive disease resistance response (HR), and S-nitrosylation is emerging as an important mechanism for the transduction of its bioactivity. A key step toward elucidating the mechanisms by which NO functions during the HR...... metabolism, signaling and antioxidant defense. The study of the effects of S-nitrosylation on the activity of the identified proteins and its role during the execution of the disease resistance response will help to understand S-nitrosylation function and significance in plants....

  15. Formation of conductive polymers using nitrosyl ion as an oxidizing agent

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung-Shin; Jung, Yongju; Singh, Nikhilendra

    2016-06-07

    A method of forming a conductive polymer deposit on a substrate is disclosed. The method may include the steps of preparing a composition comprising monomers of the conductive polymer and a nitrosyl precursor, contacting the substrate with the composition so as to allow formation of nitrosyl ion on the exterior surface of the substrate, and allowing the monomer to polymerize into the conductive polymer, wherein the polymerization is initiated by the nitrosyl ion and the conductive polymer is deposited on the exterior surface of the substrate. The conductive polymer may be polypyrrole.

  16. Characterization of Mononuclear Non-heme Iron(III)-Superoxo Complex with a Five-Azole Ligand Set.

    Science.gov (United States)

    Oddon, Frédéric; Chiba, Yosuke; Nakazawa, Jun; Ohta, Takehiro; Ogura, Takashi; Hikichi, Shiro

    2015-06-15

    Reaction of O2 with a high-spin mononuclear iron(II) complex supported by a five-azole donor set yields the corresponding mononuclear non-heme iron(III)-superoxo species, which was characterized by UV/Vis spectroscopy and resonance Raman spectroscopy. (1)H NMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low-spin iron(III) and superoxide. This superoxo species reacts with H-atom donating reagents to give a low-spin iron(III)-hydroperoxo species showing characteristic UV/Vis, resonance Raman, and EPR spectra. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Fungal Iron Availability during Deep Seated Candidiasis Is Defined by a Complex Interplay Involving Systemic and Local Events

    Science.gov (United States)

    Potrykus, Joanna; Stead, David; MacCallum, Donna M.; Urgast, Dagmar S.; Raab, Andrea; van Rooijen, Nico; Feldmann, Jörg; Brown, Alistair J. P.

    2013-01-01

    Nutritional immunity – the withholding of nutrients by the host – has long been recognised as an important factor that shapes bacterial-host interactions. However, the dynamics of nutrient availability within local host niches during fungal infection are poorly defined. We have combined laser ablation-inductively coupled plasma mass spectrometry (LA-ICP MS), MALDI imaging and immunohistochemistry with microtranscriptomics to examine iron homeostasis in the host and pathogen in the murine model of systemic candidiasis. Dramatic changes in the renal iron landscape occur during disease progression. The infection perturbs global iron homeostasis in the host leading to iron accumulation in the renal medulla. Paradoxically, this is accompanied by nutritional immunity in the renal cortex as iron exclusion zones emerge locally around fungal lesions. These exclusion zones correlate with immune infiltrates and haem oxygenase 1-expressing host cells. This local nutritional immunity decreases iron availability, leading to a switch in iron acquisition mechanisms within mature fungal lesions, as revealed by laser capture microdissection and qRT-PCR analyses. Therefore, a complex interplay of systemic and local events influences iron homeostasis and pathogen-host dynamics during disease progression. PMID:24146619

  18. Fungal iron availability during deep seated candidiasis is defined by a complex interplay involving systemic and local events.

    Directory of Open Access Journals (Sweden)

    Joanna Potrykus

    Full Text Available Nutritional immunity--the withholding of nutrients by the host--has long been recognised as an important factor that shapes bacterial-host interactions. However, the dynamics of nutrient availability within local host niches during fungal infection are poorly defined. We have combined laser ablation-inductively coupled plasma mass spectrometry (LA-ICP MS, MALDI imaging and immunohistochemistry with microtranscriptomics to examine iron homeostasis in the host and pathogen in the murine model of systemic candidiasis. Dramatic changes in the renal iron landscape occur during disease progression. The infection perturbs global iron homeostasis in the host leading to iron accumulation in the renal medulla. Paradoxically, this is accompanied by nutritional immunity in the renal cortex as iron exclusion zones emerge locally around fungal lesions. These exclusion zones correlate with immune infiltrates and haem oxygenase 1-expressing host cells. This local nutritional immunity decreases iron availability, leading to a switch in iron acquisition mechanisms within mature fungal lesions, as revealed by laser capture microdissection and qRT-PCR analyses. Therefore, a complex interplay of systemic and local events influences iron homeostasis and pathogen-host dynamics during disease progression.

  19. Complex electrical monitoring of biopolymer and iron mineral precipitation for microbial enhanced hydrocarbon recovery

    Science.gov (United States)

    Wu, Y.; Hubbard, C. G.; Dong, W.; Hubbard, S. S.

    2011-12-01

    Microbially enhanced hydrocarbon recovery (MEHR) mechanisms are expected to be impacted by processes and properties that occur over a wide range of scales, ranging from surface interactions and microbial metabolism at the submicron scale to changes in wettability and pore geometry at the pore scale to geological heterogeneities at the petroleum reservoir scale. To eventually ensure successful, production-scale implementation of laboratory-developed MEHR procedures under field conditions, it is necessary to develop approaches that can remotely monitor and accurately predict the complex microbially-facilitated transformations that are expected to occur during MEHR treatments in reservoirs (such as the evolution of redox profiles, oil viscosity or matrix porosity/permeability modifications). Our initial studies are focused on laboratory experiments to assess the geophysical signatures of MEHR-induced biogeochemical transformations, with an ultimate goal of using these approaches to monitor field treatments. Here, we explore the electrical signatures of two MEHR processes that are designed to produce end-products that will plug high permeability zones in reservoirs and thus enhance sweep efficiency. The MEHR experiments to induce biopolymers (in this case dextran) and iron mineral precipitates were conducted using flow-through columns. Leuconostoc mesenteroides, a facultative anaerobe, known to produce dextran from sucrose was used in the biopolymer experiments. Paused injection of sucrose, following inoculation and initial microbial attachment, was carried out on daily basis, allowing enough time for dextran production to occur based on batch experiment observations. Electrical data were collected on daily basis and fluid samples were extracted from the column for characterization. Changes in electrical signal were not observed during initial microbial inoculation. Increase of electrical resistivity and decrease of electrical phase response were observed during the

  20. Synthesis, crystal structure and reactivity studies of iron complexes with pybox ligands

    KAUST Repository

    Chen, Tao

    2014-11-01

    Iron(II) complexes, [Fe(2,6-bis(4,4-dimethyl-1,3-oxazolin-2-yl)pyridine)Cl2] ((Fe(Me2-pybox)Cl2), 3) and [Fe(2,6-bis(4,4-diphenyl-1,3-oxazolin-2-yl)pyridine)Cl2] ((Fe(Ph2-pybox)Cl2), 4), have been synthesized and characterized by X-ray crystallographic analysis. Upon treatment of complex 3 with silver triflate and 4 with acetonitrile, [Fe(Me2-pybox)(CH3CN)OTf2] (5) and [Fe(Ph2-pybox)(CH3CN)2Cl][FeCl3] (6) were obtained, respectively. The bulkier phenyl substitutes were found not only to cause the elongation of the N-Fe bonds but also influence the reactivity of the Fe center.

  1. The synthesis, structures and characterisation of new mixed-ligand manganese and iron complexes with tripodal, tetradentate ligands

    NARCIS (Netherlands)

    van Gorkum, R.; Berding, J.; Mills, A.M.; Kooijman, H.; Tooke, D.M.; Spek, A.L.; Mutikainen, I.; Turpeinen, U.; Reedijk, J.; Bouwman, E.

    2008-01-01

    The preparation of new manganese and iron complexes with the general formula [M(tripod)(anion)] is described, where M = FeIII or MnIII, “tripod” is a dianionic tetradentate tripodal ligand and the anion is a chelating β-diketonate, 8-oxyquinoline or acetate. The synthesis of this type of complexes

  2. Synthesis of (R)-BINOL-Derived (Cyclopentadienone)iron Complexes and Their Application in the Catalytic Asymmetric Hydrogenation of Ketones

    NARCIS (Netherlands)

    Gajewski, Piotr; Renom-Carrasco, Marc; Facchini, Sofia Vailati; Pignataro, Luca; Lefort, Laurent; de Vries, Johannes G.; Ferraccioli, Raffaella; Piarulli, Umberto; Gennari, Cesare

    A family of chiral (cyclopentadienone)iron complexes, featuring an (R)-BINOL-derived backbone, and their application in the asymmetric hydrogenation of ketones are described. The complexes differ from each other in the substituents at the 3,3-positions of the binaphthyl residue (H, OH, OR, OCOR,

  3. Chemistry of extractable nitrosyl ruthenium species in the system nitric acid-tributyl phosphate-dodecane

    International Nuclear Information System (INIS)

    Maya, L.

    1981-01-01

    Fission product ruthenium is present in solutions resulting from the dissolution of spent nuclear fuel in the form of nitro and nitrato complexes of nitrosyl ruthenium. A fraction of the ruthenium, mostly higher nitrato complexes, is extracted into the organic solvent phase in the Purex process. Stripping tests reveal a component in the solvent phase that cannot be readily transferred to the aqueous phase. Experiments were performed to determine whether the retained fraction is a highly extractable species originally present in the aqueous phase or if it is the product of a reaction between the extracted species and the solvent. A chromatographic procedure was developed to separate the species in the aqueous phase. This revealed a species more extractable than the tetranitrato complex; however, since the separation process involved TBP, the ambiguity regarding the origin of this species could not be resolved. On the other hand, in a separate series of experiments evidence was found showing that the retained species result from a reversible reaction in the solvent phase. The equilibrium concentration of this species is dependent on the temperature and the tributyl phosphate activity. This complex apparently results from the substitution of aquo ligands in the extracted species by tributyl phosphate. (author)

  4. Gas-phase complexes formed between amidoxime ligands and vanadium or iron investigated using electrospray ionization mass spectrometry.

    Science.gov (United States)

    Mustapha, Adetayo M; Pasilis, Sofie P

    2016-08-15

    Amidoxime-functionalized sorbents can be used to extract uranium from seawater. Iron(III) and vanadium(V) may compete with uranium for adsorption sites. We use 2,6-dihydroxyiminopiperidine (DHIP) and N(1) ,N(5) -dihydroxypentanediimidamide (DHPD) to model amidoxime functional groups and characterize the vanadium(V) and iron(III) complexes with these ligands. We also examine the effect of iron(III) and vanadium(V) on uranyl(VI) complexation by DHIP and DHPD. The experiments were carried out in positive ion mode using a quadrupole ion trap mass spectrometer equipped with an electrospray ionization source. The effect on the mass spectra of changes in ligand, metal:ligand mole ratio, and pH was examined. Iron(III) formed a 1:2 metal:ligand complex with DHIP at all metal:ligand mole ratios and pH values investigated; it formed both 1:2 and 1:3 metal:ligand complexes with DHPD. Vanadium(V) formed 1:1 and 1:2 metal:ligand complexes with DHIP. A 1:2 metal:ligand complex was formed with DHPD at all vanadium(V):DHPD mole ratios investigated. Changes in solution pH did not affect the ions observed. The relative binding affinities of the metal ions towards DHIP followed the order iron(III) > vanadium(V) > uranyl(VI). This study presents a first look at the gas-phase vanadium(V)- and iron(III)-DHIP and -DHPD complexes using electrospray ionization mass spectrometry. These metals form stronger complexes with amidoxime ligands than uranyl(VI), and will affect uranyl(VI) adsorption to amidoxime-based sorbents. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes.

    Science.gov (United States)

    Yan, Jinlong; Jiang, Tao; Yao, Ying; Lu, Song; Wang, Qilei; Wei, Shiqiang

    2016-04-01

    Iron oxide (FeO) coated by natural organic matter (NOM) is ubiquitous. The associations of minerals with organic matter (OM) significantly changes their surface properties and reactivity, and thus affect the environmental fate of pollutants, including nutrients (e.g., phosphorus (P)). In this study, ferrihydrite/goethite-humic acid (FH/GE-HA) complexes were prepared and their adsorption characteristics on P at various pH and ionic strength were investigated. The results indicated that the FeO-OM complexes showed a decreased P adsorption capacity in comparison with bare FeO. The maximum adsorption capacity (Qmax) decreased in the order of FH (22.17 mg/g)>FH-HA (5.43 mg/g)>GE (4.67 mg/g)>GE-HA (3.27 mg/g). After coating with HA, the amorphous FH-HA complex still showed higher P adsorption than the crystalline GE-HA complex. The decreased P adsorption observed might be attributed to changes of the FeO surface charges caused by OM association. The dependence of P adsorption on the specific surface area of adsorbents suggests that the FeO component in the complexes is still the main contributor for the adsorption surfaces. The P adsorptions on FeO-HA complexes decreased with increasing initial pH or decreasing initial ionic strength. A strong dependence of P adsorption on ionic strength and pH may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the FeO component and P. Therefore, previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils, especially in humic-rich areas. Copyright © 2015. Published by Elsevier B.V.

  6. Ruthenium nitrosyls derived from tetradentate ligands containing carboxamido-N and phenolato-o donors: syntheses, structures, photolability, and time dependent density functional theory studies.

    Science.gov (United States)

    Fry, Nicole L; Rose, Michael J; Rogow, David L; Nyitray, Crystal; Kaur, Manpreet; Mascharak, Pradip K

    2010-02-15

    In order to examine the role(s) of designed ligands on the NO photolability of {Ru-NO}(6) nitrosyls, a set of three nitrosyls with ligands containing two carboxamide groups along with a varying number of phenolates have been synthesized. The nitrosyls namely, (NEt(4))(2)[(hybeb)Ru(NO)(OEt)] (1), (PPh(4))[(hypyb)Ru(NO)(OEt)] (2), and [(bpb)Ru(NO)(OEt)] (3) have been characterized by X-ray crystallography. Complexes 1-3 are diamagnetic, exhibit nu(NO) in the range 1780-1840 cm(-1) and rapidly release NO in solution upon exposure to low power UV light (7 mW/cm(2)). Density Functional Theory (DFT) and Time Dependent DFT (TDDFT) calculations on 1-3 indicate considerable contribution of ligand orbitals in the MOs involved in transitions leading to NO photolability. The results of the theoretical studies match well with the experimental absorption spectra as well as the parameters for NO photorelease and provide insight into the transition(s) associated with loss of NO.

  7. One-electron oxidation of iron(II)-imidazole and iron-(II)-bis[imidazol-2-yl]methane complexes: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Parsons, B.J.; Navaratnam, S.; Zhao, Z.; Chen, L.

    1994-01-01

    The radical anion, Br 2 .- , a strong one-electron oxidant, has been used to oxidise iron(II)-imidazole, Fe 11 -ImH, and iron(II)-bis(imidazol-2-yl)methane, Fe 11 -2-BIM, complexes in aqueous solution, the latter being regarded as good models of the iron(II) site in non-haem iron-containing enzymes such as lipoxygenase. The rates of oxidation of Fe 11 -ImH, Fe 11 (ImH) 2 , Fe-2-BIM and Fe 11 (2-BIM) 2 were measured as 1.0 x 10 7 , 2.0 x 10 7 , 1.8 x 10 8 and 3.6 x 10 8 dm 3 mol -1 s -1 . From measurements of the rates of oxidation of the ligand, it is clear that Br 2 .- oxidises the ligand in the metal complexes in the first instance. The same studies also show that the 2-BIM ligand is easier to oxidise than the closely related imidazole ligand by a factor of 10. Measurements of the rate of oxidation of 2-methylimidazole indicate that the difference is attributable to the inductive effect of the -CH 2 -group. (author)

  8. Synthesis, characterization, and reactivity of furan- and thiophene-functionalized bis(n-heterocyclic carbene) complexes of iron(II)

    KAUST Repository

    Rieb, Julia

    2014-09-15

    The synthesis of iron(II) complexes bearing new heteroatom-functionalized methylene-bridged bis(N-heterocyclic carbene) ligands is reported. All complexes are characterized by single-crystal X-ray diffraction (SC-XRD), nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. Tetrakis(acetonitrile)-cis-[bis(o-imidazol-2-ylidenefuran)methane]iron(II) hexafluorophosphate (2a) and tetrakis(acetonitrile)-cis-[bis(o-imidazol-2-ylidenethiophene)methane]iron(II) hexafluorophosphate (2b) were obtained by aminolysis of [Fe{N(SiMe3)2}2(THF)] with furan- and thiophene-functionalized bis(imidazolium) salts 1a and 1b in acetonitrile. The SC-XRD structures of 2a and 2b show coordination of the bis(carbene) ligand in a bidentate fashion instead of a possible tetradentate coordination. The four other coordination sites of these distorted octahedral complexes are occupied by acetonitrile ligands. Crystallization of 2a in an acetone solution by the slow diffusion of Et2O led to the formation of cisdiacetonitriledi[ bis(o-imidazol-2-ylidenefuran)methane]iron(II) hexafluorophosphate (3a) with two bis(carbene) ligands coordinated in a bidentate manner and two cis-positioned acetonitrile molecules. Compounds 2a and 2b are the first reported iron(II) carbene complexes with four coordination sites occupied by solvent molecules, and it was demonstrated that those solvent ligands can undergo ligand-exchange reactions.

  9. The therapeutic value of protein (de)nitrosylation in experimental septic shock.

    Science.gov (United States)

    Benedet, Patrícia O; Menegatti, Angela C O; Gonçalves, Muryel C; Terenzi, Hernán; Assreuy, Jamil

    2018-01-01

    Cardiovascular dysfunction and organ damage are hallmarks of sepsis and septic shock. Protein S-nitrosylation by nitric oxide has been described as an important modifier of protein function. We studied whether protein nitrosylation/denitrosylation would impact positively in hemodynamic parameters of septic rats. Polymicrobial sepsis was induced by cecal ligation and puncture. Female Wistar rats were treated with increasing doses of DTNB [5,5'-dithio-bis-(2-nitrobenzoic acid)] 30min before or 4 or 12h after sepsis induction. Twenty-four hours after surgery the following data was obtained: aorta response to phenylephrine, mean arterial pressure, vascular reactivity to phenylephrine, biochemical markers of organ damage, survival and aorta protein nitrosylation profile. Sepsis substantially decreases blood pressure and the response of aorta rings and of blood pressure to phenylephrine, as well as increased plasma levels of organ damage markers, mortality of 60% and S-nitrosylation of aorta proteins increased during sepsis. Treatment with DTNB 12h after septic shock induction reversed the loss of response of aorta rings and blood pressure to vasoconstrictors, reduced organ damage and protein nitrosylation and increased survival to 80%. Increases in protein S-nitrosylation are related to cardiovascular dysfunction and multiple organ injury during sepsis. Treatment of rats with DTNB reduced the excessive protein S-nitrosylation, including that in calcium-dependent potassium channels (BK Ca ), reversed the cardiovascular dysfunction, improved markers of organ dysfunction and glycemic profile and substantially reduced mortality. Since all these beneficial consequences were attained even if DTNB was administered after septic shock onset, protein (de)nitrosylation may be a suitable target for sepsis treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

    Energy Technology Data Exchange (ETDEWEB)

    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry

    1998-05-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  11. [Asbestos-stimulated changes in nitric oxide and iron metabolism in rats].

    Science.gov (United States)

    Shandarenko, S H; Kishko, T O; Chumachenko, I M; Dmytrenko, M P

    2011-01-01

    Under intratracheal asbestos fibers installation it has been investigated NO synthesis in the lung and liver tissues of Wistar rats by EPR method. Asbestos A6-45, sifted through the sieve with size 0.1 mm, has been administrated in a dose of 5 mg/kg. To evaluate the NO synthesis EPR and NO-trap methods have been used. The amplitude of EPR signal "trap-NO" in the lung samples was 12, 16 and 14 times greater than in controls on the 3th, 6th and 10th days after asbestos installation and was corresponding to NO rate of about 2 mkmol/(g x h). In the liver samples of asbestos-stimulated animals the NO level contained in the non-heme iron nitrosyl complexes was about 2 mkmol/g. Thus, the asbestos fibers stimulate NO synthesis not only in the lung tissue, but also in other organs. The obtained data shows that under NO hyperproduction certain changes in iron metabolism take place, such as: the decrease of transferrin iron and the accumulation of ferric iron not bound with transferrin. The accumulation of ferric iron not shielded by proteins is one of the oxidative stress triggers.

  12. Assessment of serum copper, iron and immune complexes in potentially malignant disorders and oral cancer

    Directory of Open Access Journals (Sweden)

    Ritu TIWARI

    Full Text Available Abstract Potentially malignant disorders (PMDs of oral cavity and oral cancer remain a cause of serious concern despite intensive research and development. Diet and immunity have been identified to play a crucial role as modifying factors in these diseases. Our study intended to explore this relationship by estimating and comparing the serum levels of copper, iron and circulating immune complexes (CICs in patients diagnosed with PMDs and oral cancer and normal healthy individuals. In this study, 40 histopathologically diagnosed cases of PMDs and oral cancer were included along with 30 healthy controls and 5 ml of venous blood was drawn using venipuncture. Serum estimation of copper, iron and CIC then followed using the colorimetric and spectrophotometric methods. The data obtained was subjected to statistical analysis using one way ANOVA and Pearson’s Product-Moment Correlation Test. The mean serum copper level was measured as 138.98 ± 10.13µg/100ml in the PMD group and 141.99 ± 21.44 µg/100ml in the oral cancer as compared to 105.5 + 18.81µ/100ml in the controls. The mean serum CIC levels was highest in the oral cancer (9.65 ± 0.16OD470 followed by the PMD group (0.18 + 0.21 OD470 and least in the control group (0.048 ± 0.02OD470. Whereas, the serum levels of iron showed a significant decrease in the PMD group (110.9 ± 10.54 µg/100ml and the oral cancer group (114.29 ± 25.83 µg/100ml as compared with the control group (136.85 ± 14.48 µg/100ml. There was no positive correlation obtained between the three groups with respect to the chosen parameters indicating that the variables were independent of each other. It can be thus be ascertained that trace elements like copper and iron as well as humoral responses (CICs have a close relationship with PMDs and oral cancers.

  13. Respiratory Chain Supercomplexes associate with the Cysteine Desulfurase Complex of the Iron-Sulfur Cluster Assembly Machinery.

    Science.gov (United States)

    Böttinger, Lena; Mårtensson, Christoph U; Song, Jiyao; Zufall, Nicole; Wiedemann, Nils; Becker, Thomas

    2018-01-31

    Mitochondria are the powerhouses of eukaryotic cells. The activity of the respiratory chain complexes generates a proton gradient across the inner membrane, which is used by the F 1 F O -ATP synthase to produce ATP for cellular metabolism. In baker's yeast Saccharomyces cerevisiae the cytochrome bc1 complex (complex III) and cytochrome c oxidase (complex IV) associate in respiratory chain supercomplexes. Iron-sulfur clusters (ISC) form reactive centers of respiratory chain complexes. The assembly of ISC occurs in the mitochondrial matrix and is essential for cell viability. The cysteine desulfurase Nfs1 provides sulfur for ISC assembly and forms with partner proteins the ISC-biogenesis desulfurase complex (ISD complex). Here, we report an unexpected interaction of the active ISD complex with the cytochrome bc1 complex and cytochrome c oxidase. The individual deletion of complex III or complex IV blocks the association of the ISD complex with respiratory chain components. We conclude that the ISD complex binds selectively to respiratory chain supercomplexes. We propose that this molecular link contributes to coordination of iron-sulfur cluster formation with respiratory activity. © 2018 by The American Society for Cell Biology.

  14. Tracking the picosecond deactivation dynamics of a photoexcited iron carbene complex by time-resolved X-ray scattering

    DEFF Research Database (Denmark)

    Leshchev, Denis; Harlang, Tobias C. B.; Fredin, Lisa A.

    2018-01-01

    Recent years have seen the development of new iron-centered N-heterocyclic carbene (NHC) complexes for solar energy applications. Compared to typical ligand systems, the NHC ligands provide Fe complexes with longer-lived metal-to-ligand charge transfer (MLCT) states. This increased lifetime......)pyridine) is a unique complex as it exhibits a short-lived MC state with a lifetime on the scale of a few hundreds of picoseconds. Hence, this complex allows for a detailed investigation, using 100 ps X-ray pulses from a synchrotron, of strong ligand field effects on the intermediate MC state in an NHC complex. Here...

  15. Iron and nickel complexes with heterocyclic ligands: stability, synthesis, spectral characterization, antimicrobial activity, acute and subacute toxicity.

    Science.gov (United States)

    Bouchoucha, Afaf; Terbouche, Achour; Zaouani, Mohamed; Derridj, Fazia; Djebbar, Safia

    2013-07-01

    The synthesis and characterization by elemental analysis, emission atomic spectroscopy, TG measurements, magnetic measurements, FTIR, (1)H NMR, UV-visible spectra and conductivity of a series of iron (II) and nickel (II) complexes with two heterocyclic ligands (L(1)(SMX): sulfamethoxazole and L(2)(MIZ): metronidazole) used in pharmaceutical field and with a new ligand derived benzoxazole (L(3)(MPBO): 2-(5-methylpyridine-2-yl)benzoxazole), were reported. The formulae obtained for the complexes are: [M(L(1))2 Cl2]·nH2O, [M(L(2))2Cl2(H2O)2]·H2O and [M(L(3))2(OH)2]·nH2O. Stability constants of these complexes have been determined by potentiometric methods in water-ethanol (90:10, v/v) mixture at a 0.2 mol L(-1) ionic strength (NaCl) and at 25.0±0.1 °C. Sirko program was used to determine the protonation constants as well as the binding constants of three species [ML2H2](2+), [ML2] and [ML](2+). The antimicrobial activity of the ligands and complexes was evaluated in vitro against different human bacteria and fungi using agar diffusion method. Iron sulfamethoxazole complex showed a remarkable inhibition of bacteria growth especially on Staphylococcus aureus and P. aeruginosa. The iron metronidazole complex is active against yeasts especially on Candida tropicalis strain. Nickel complexes presented different antibacterial and antifungal behavior's against bacteria and fungal. The acute toxicity study revealed that the iron complexes are not toxic at 2000 mg/kg dose orally administrated. LD50 for nickel complexes was determined using graphical method. No significant differences in the body weights between the control and the treated groups of both rat sexes in subacute toxicity study using for iron complexes. Hematological and clinical blood chemistry analysis revealed no toxicity effects of the iron complexes. Pathologically, neither gross abnormalities nor histopathological changes were observed for these complexes. Copyright © 2013 Elsevier GmbH. All rights

  16. INTRAVENOUS IRON-SUCROSE COMPLEX THERAPY IN PREGNANT WOMEN WITH IRON DEFICIENCY ANAEMIA- A STUDY IN TERTIARY CENTRE

    Directory of Open Access Journals (Sweden)

    Todak Taba

    2017-11-01

    Full Text Available BACKGROUND Anaemia in pregnancy continues to be a major public health problem with 54.96% of the pregnant population suffering from it in our setup. Despite the National Anaemia Prophylaxis Programme, anaemia complicating pregnancy continues to be a widespread problem with adverse effects on maternal and foetal outcome. The aim of the study is to find out an alternate iron therapy in the form of intravenous iron-sucrose and to determine its therapeutic effectiveness, safety and compliance in the management of anaemic expectant mother and to compare it with that of conventional oral iron therapy. MATERIALS AND METHODS The study was a randomised controlled clinical trial carried out in the Department of Obstetrics and Gynaecology in collaboration with the Department of Biochemistry, Regional Institute of Medical Sciences (RIMS, Imphal. 100 pregnant women in second or third trimester with mild or moderate anaemia were selected, 50 as study group (intravenous iron and 50 as controls (oral iron. Initial evaluation included complete blood count and serum ferritin level and reevaluated on the 14th and 28th day of initiation of therapy. RESULTS Majority of patients (42% in the study as well as control group were between 26-30 years of age. The mean ± SD increase in haemoglobin and ferritin levels on 28th day were 2.66 ± 0.34 gm/dL and 27.65 ± 1.80 ng/mL in study group and 1.55 ± 0.23 gm/dL and 16.89 ± 0.76 ng/mL in control group respectively, both of which were statistically significant. CONCLUSION The mean haemoglobin and serum ferritin levels throughout the treatment were significantly higher in the intravenous ironsucrose group than in the orally administered iron group and significantly higher number of patients achieved the target haemoglobin of 11.0 gm/dL after 28 days of treatment. This reduces the blood transfusion rates in pregnant women with severe anaemia near term.

  17. The organic complexation of iron in the marine environment: A review

    Directory of Open Access Journals (Sweden)

    Martha eGledhill

    2012-02-01

    Full Text Available Iron (Fe is an essential micronutrient for marine organisms, and it is now well established that low Fe availability controls phytoplankton productivity, community structure and ecosystem functioning in vast regions of the global ocean. The biogeochemical cycle of Fe involves complex interactions between lithogenic inputs (atmospheric, continental or hydrothermal, dissolution, precipitation, scavenging, biological uptake, remineralisation and sedimentation processes. Each of these aspects of Fe biogeochemical cycling is likely influenced by organic Fe-binding ligands, which complex more than 99% of dissolved Fe. In this review we consider recent advances in our knowledge of Fe complexation in the marine environment and their implications for the biogeochemistry of Fe in the ocean. We also highlight the importance of constraining the dissolved Fe concentration value used in interpreting voltammetric titration data for the determination of Fe speciation. Within the published Fe speciation data, there appear to be important temporal and spatial variations in Fe-binding ligand concentrations and their conditional stability constants in the marine environment. Excess ligand concentrations, particularly in the truly soluble size fraction, seem to be consistently higher in the upper water column, and especially in Fe-limited, but productive, waters. Evidence is accumulating for an association of Fe with both small, well-defined ligands, such as siderophores, as well as with larger, macromolecular complexes like humic substances, exopolymeric substances and transparent exopolymers. The diverse size spectrum and chemical nature of Fe-ligand complexes corresponds to a change in kinetic inertness which will have a consequent impact on biological availability. However, much work is still to be done in coupling voltammetry, mass spectrometry techniques and process studies to better characterize the nature and cycling of Fe-binding ligands in the marine

  18. Moessbauer spectroscopic evidence for iron(III) complexation and reduction in acidic aqueous solutions of indole-3-butyric acid

    International Nuclear Information System (INIS)

    Kovacs, K.; Kuzmann, E.; Vertes, A.; Kamnev, A.A.; Shchelochkov, A.G.; Medzihradszky-Schweiger, H.; Mink, J.; Hungarian Academy of Sciences, Budapest

    2004-01-01

    Moessbauer spectroscopic studies were carried out in acidic (pH 2.3) 57 Fe III nitrate containing aqueous solutions of indole-3-butyric acid (IBA), rapidly frozen in liquid nitrogen at various periods of time after mixing the reagents. The data obtained show that in solution in the presence of IBA, iron(III) forms a complex with a dimeric structure characterised by a quadrupole doublet, whereas without IBA under similar conditions iron(III) exhibits a broad spectral feature due to a slow paramagnetic spin relaxation which, at liquid nitrogen temperature, results in a large anomalous line broadening (or, at T = 4.2 K, in a hyperfine magnetic splitting). The spectra of 57 Fe III +IBA solutions, kept at ambient temperature under aerobic conditions for increasing periods of time before freezing, contained a gradually increasing contribution of a component with a higher quadrupole splitting. The Moessbauer parameters for that component are typical for iron(II) aquo complexes, thus showing that under these conditions gradual reduction of iron(III) occurs, so that the majority (85%) of dissolved iron(III) is reduced within 2 days. The Moessbauer parameters for the iron(III)-IBA complex in aqueous solution and in the solid state (separated from the solution by filtration) were found to be similar, which may indicate that the dissolved and solid complexes have the same composition and/or iron(III) coordination environment. For the solid complex, the data of elemental analysis suggest the following composition of the dimer: [L 2 Fe-(OH) 2 -FeL 2 ] (where L is indole-3-butyrate). This structure is also in agreement with the data of infrared spectroscopic study of the complex reported earlier, with the side-chain carboxylic group in indole-3-butyrate as a bidentate ligand. The Moessbauer parameters for the solid 57 Fe III -IBA complex at T = 80 K and its acetone solution rapidly frozen in liquid nitrogen were virtually identical, which indicates that the complex retains its

  19. Influence of Ligand Architecture in Tuning Reaction Bifurcation Pathways for Chlorite Oxidation by Non-Heme Iron Complexes

    NARCIS (Netherlands)

    Barman, Prasenjit; Faponle, Abayomi S; Vardhaman, Anil Kumar; Angelone, Davide; Löhr, Anna-Maria; Browne, Wesley R; Comba, Peter; Sastri, Chivukula V; de Visser, Sam P

    2016-01-01

    Reaction bifurcation processes are often encountered in the oxidation of substrates by enzymes and generally lead to a mixture of products. One particular bifurcation process that is common in biology relates to electron transfer versus oxygen atom transfer by high-valent iron(IV)-oxo complexes,

  20. Bio-inspired iron and manganese complexes derived from mixed N,O ligands for the oxidation of olefins

    NARCIS (Netherlands)

    Moelands, M.A.H.

    2014-01-01

    This Thesis describes the synthesis and structural analysis of bio-inspired iron and manganese complexes used for the catalytic oxidation of olefin substrates. The development of catalytic systems for oxidation chemistry that are based on first row transition metals and that apply a green oxidant

  1. A functional mimic of natural peroxidases : synthesis and catalytic activity of a non-heme iron peptide hydroperoxide complex

    NARCIS (Netherlands)

    Choma, CT; Schudde, EP; Kellogg, RM; Robillard, GT; Feringa, BL

    1998-01-01

    Site-selective attachment of unprotected peptides to a non-heme iron complex is achieved by displacing two halides on the catalyst by peptide caesium thiolates, This coupling approach should be compatible with any peptide sequence provided there is only a single reduced cysteine. The oxidation

  2. After Effects of the 57Co(EC)57Fe-Reaction in some Cobalt and Iron Complexes

    DEFF Research Database (Denmark)

    Siekierska, K. F.; Fenger, Jørgen Folkvard; Olsen, J.

    1972-01-01

    Mössbauer emission spectra of iron and cobalt complexes, doped or labelled with 57Co, demonstrate that the 57Co(EC)57Fe reaction can have significant chemical effects, although the probability of displacement of the nascent57Fe is very low. Measurements on specifically 57Co-labelled [Co(bipy)3][Co...

  3. Novel iron complexes bearing N6-substituted adenosine derivatives: Synthesis, magnetic, Fe-57 Mossbauer, DFT, and in vitro cytotoxicity studies

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Mikulík, J.; Čajan, Michal; Zbořil, R.; Popa, Igor

    2008-01-01

    Roč. 16, č. 18 (2008), s. 8719-8728 ISSN 0968-0896 Institutional research plan: CEZ:AV0Z50380511 Keywords : iron complexes * adenosine derivatives * Fe-57 Mossbauer spectroscopy Subject RIV: CE - Biochemistry Impact factor: 3.075, year: 2008

  4. Iron-Targeting Antitumor Activity of Gallium Compounds and Novel Insights Into Triapine®-Metal Complexes

    Science.gov (United States)

    Antholine, William E.

    2013-01-01

    Abstract Significance: Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Recent Advances: Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise for the treatment of cancer. Recent studies show that gallium compounds and metal-thiosemicarbazone complexes inhibit tumor cell growth by targeting iron homeostasis, including iron-dependent ribonucleotide reductase. Chemical similarities of gallium(III) with iron(III) enable the former to mimic the latter and interpose itself in critical iron-dependent steps in cellular proliferation. Newer gallium compounds have emerged with additional mechanisms of action. In clinical trials, the first-generation-compound gallium nitrate has exhibited activity against bladder cancer and non-Hodgkin's lymphoma, while the thiosemicarbazone Triapine® has demonstrated activity against other tumors. Critical Issues: Novel gallium compounds with greater cytotoxicity and a broader spectrum of antineoplastic activity than gallium nitrate should continue to be developed. Future Directions: The antineoplastic activity and toxicity of the existing novel gallium compounds and thiosemicarbazone-metal complexes should be tested in animal tumor models and advanced to Phase I and II clinical trials. Future research should identify biologic markers that predict tumor sensitivity to gallium compounds. This will help direct gallium-based therapy to cancer patients who are most likely to benefit from it. Antioxid. Redox Signal. 00, 000–000. PMID:22900955

  5. S-nitrosylation/denitrosylation as a regulatory mechanism of salt stress sensing in sunflower seedlings.

    Science.gov (United States)

    Jain, Prachi; von Toerne, Christine; Lindermayr, Christian; Bhatla, Satish C

    2018-01-01

    Nitric oxide (NO) and various reactive nitrogen species produced in cells in normal growth conditions, and their enhanced production under stress conditions are responsible for a variety of biochemical aberrations. The present findings demonstrate that sunflower seedling roots exhibit high sensitivity to salt stress in terms of nitrite accumulation. A significant reduction in S-nitrosoglutathione reductase (GSNOR) activity is evident in response to salt stress. Restoration of GSNOR activity with dithioerythritol shows that the enzyme is reversibly inhibited under conditions of 120 mM NaCl. Salt stress-mediated S-nitrosylation of cytosolic proteins was analyzed in roots and cotyledons using biotin-switch assay. LC-MS/MS analysis revealed opposite patterns of S-nitrosylation in seedling cotyledons and roots. Salt stress enhances S-nitrosylation of proteins in cotyledons, whereas roots exhibit denitrosylation of proteins. Highest number of proteins having undergone S-nitrosylation belonged to the category of carbohydrate metabolism followed by other metabolic proteins. Of the total 61 proteins observed to be regulated by S-nitrosylation, 17 are unique to cotyledons, 4 are unique to roots whereas 40 are common to both. Eighteen S-nitrosylated proteins are being reported for the first time in plant systems, including pectinesterase, phospholipase d-alpha and calmodulin. Further physiological analysis of glyceraldehyde-3-phosphate dehydrogenase and monodehydroascorbate reductase showed that salt stress leads to a reversible inhibition of both these enzymes in cotyledons. However, seedling roots exhibit enhanced enzyme activity under salinity stress. These observations implicate the role of S-nitrosylation and denitrosylation in NO signaling thereby regulating various enzyme activities under salinity stress in sunflower seedlings. © 2017 Scandinavian Plant Physiology Society.

  6. Preclinical therapeutic potential of a nitrosylating agent in the treatment of ovarian cancer.

    Directory of Open Access Journals (Sweden)

    Shailendra Giri

    Full Text Available This study examines the role of s-nitrosylation in the growth of ovarian cancer using cell culture based and in vivo approaches. Using the nitrosylating agent, S-nitrosoglutathione (GSNO, a physiological nitric oxide molecule, we show that GSNO treatment inhibited proliferation of chemoresponsive and chemoresistant ovarian cancer cell lines (A2780, C200, SKVO3, ID8, OVCAR3, OVCAR4, OVCAR5, OVCAR7, OVCAR8, OVCAR10, PE01 and PE04 in a dose dependent manner. GSNO treatment abrogated growth factor (HB-EGF induced signal transduction including phosphorylation of Akt, p42/44 and STAT3, which are known to play critical roles in ovarian cancer growth and progression. To examine the therapeutic potential of GSNO in vivo, nude mice bearing intra-peritoneal xenografts of human A2780 ovarian carcinoma cell line (2 × 10(6 were orally administered GSNO at the dose of 1 mg/kg body weight. Daily oral administration of GSNO significantly attenuated tumor mass (p<0.001 in the peritoneal cavity compared to vehicle (phosphate buffered saline treated group at 4 weeks. GSNO also potentiated cisplatin mediated tumor toxicity in an A2780 ovarian carcinoma nude mouse model. GSNO's nitrosylating ability was reflected in the induced nitrosylation of various known proteins including NFκB p65, Akt and EGFR. As a novel finding, we observed that GSNO also induced nitrosylation with inverse relationship at tyrosine 705 phosphorylation of STAT3, an established player in chemoresistance and cell proliferation in ovarian cancer and in cancer in general. Overall, our study underlines the significance of S-nitrosylation of key cancer promoting proteins in modulating ovarian cancer and proposes the therapeutic potential of nitrosylating agents (like GSNO for the treatment of ovarian cancer alone or in combination with chemotherapeutic drugs.

  7. Evidence for an iron-hydrogen complex in p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, S., E-mail: simon.leonard@manchester.ac.uk; Markevich, V. P.; Peaker, A. R.; Hamilton, B. [Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Murphy, J. D. [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-07-20

    Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90–120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at E{sub v} + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10{sup −17} cm{sup 2}. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

  8. Synthesis and characterization of an iron complex bearing a hemilabile NNN-pincer for catalytic hydrosilylation of organic carbonyl compounds.

    Science.gov (United States)

    Lin, Hsiu-Jung; Lutz, Sean; O'Kane, Catherine; Zeller, Matthias; Chen, Chun-Hsing; Al Assil, Talal; Lee, Wei-Tsung

    2018-03-06

    A low-coordinate iron(ii) complex (Cz tBu (Pz tBu ) 2 )Fe[N(SiMe 3 ) 2 ], 1 bearing an NNN-pincer ligand was prepared and fully characterized. Intramolecular C-H activation on the 5-position of a pyrazole at elevated temperatures was observed. Complex 1 was found to be an efficient and chemoselective pre-catalyst for the hydrosilylation of organo carbonyl substrates.

  9. Highly active and selective photochemical reduction of CO2 to CO using molecular-defined cyclopentadienone iron complexes.

    Science.gov (United States)

    Rosas-Hernández, Alonso; Alsabeh, Pamela G; Barsch, Enrico; Junge, Hernrik; Ludwig, Ralf; Beller, Matthias

    2016-06-28

    Herein, we report highly active (cyclopentadienone)iron-tricarbonyl complexes for CO2 photoreduction using visible light with an Ir complex as photosensitizer and TEOA as electron/proton donor. Turnover numbers (TON) of ca. 600 (1 h) with initial turnover frequencies (TOF) up to 22.2 min(-1) were observed. Operando FTIR measurements allowed for the proposal of a plausible mechanism for catalyst activation.

  10. Ferrous sulfate, but not iron polymaltose complex, aggravates local and systemic inflammation and oxidative stress in dextran sodium sulfate-induced colitis in rats

    Directory of Open Access Journals (Sweden)

    Toblli JE

    2015-05-01

    Full Text Available Jorge E Toblli, Gabriel Cao, Margarita Angerosa Laboratory of Experimental Medicine, Hospital Alemán, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina Background and aims: Iron deficiency is common in inflammatory bowel disease, yet oral iron therapy may worsen the disease symptoms and increase systemic and local oxidative stress. The aim of this study was to compare the effects of oral ferrous sulfate and iron polymaltose complex on inflammatory and oxidative stress markers in colitic rats.Methods: Animals were divided into four groups with ten animals each. Rats of three groups received dextran sodium sulfate to induce colitis and animals of two of these groups received 5 mg iron/kg of body weight a day, as ferrous sulfate or iron polymaltose complex, for 7 days. Gross colon anatomy, histology of colon and liver, stainings of L-ferritin, Prussian blue, hepcidin, tumor necrosis factor-α, and interleukin-6, as well serum levels of liver enzymes, inflammatory markers, and iron markers, were assessed.Results: Body weight, gross anatomy, crypt injury and inflammation scores, inflammatory parameters in liver and colon, as well as serum and liver hepcidin levels were not significantly different between colitic animals without iron treatment and colitic animals treated with iron polymaltose complex. In contrast, ferrous sulfate treatment caused significant worsening of these parameters. As opposed to ferrous sulfate, iron polymaltose complex caused less or no additional oxidative stress in the colon and liver compared to colitic animals without iron treatment.Conclusion: Iron polymaltose complex had negligible effects on colonic tissue erosion, local or systemic oxidative stress, and local or systemic inflammation, even at high therapeutic doses, and may thus represent a valuable oral treatment of iron deficiency in inflammatory bowel disease. Keywords: preclinical, oral iron treatment, tolerability, colonic tissue erosion

  11. ToF-SIMS investigation of FIB-patterning of lactoferrin by using self-assembled monolayers of iron complexes

    International Nuclear Information System (INIS)

    Tuccitto, N.; Giamblanco, N.; Marletta, G.; Licciardello, A.

    2008-01-01

    Geometrically well-defined patterns of surface-immobilized proteins can be produced with several methods. We developed a method for patterning of proteins by means of specific, non-covalent interactions between a protein and a metal complex immobilized at the surface. In particular, reproducible patterns of lactoferrin have been obtained by exploiting the different adsorption properties of this protein on a OH-terminated self-assembled monolayer (SAM) or onto an iron-containing SAM present in certain regions of the pattern. The OH-terminated SAM was etched with a focused ion beam (FIB) in order to produce square regions of bare gold. These regions were selectively covered with a SAM of iron-terpyridine complex, formed via a stepwise procedure involving the initial formation of a mixed component SAM (containing the terpyridine ligand) and the subsequent reaction with an iron(II) salt in order to produce the complex. The patterned substrate was finally allowed to interact with a lactoferrin solution. It is shown that lactoferrin selectively and stably adsorbs on iron-containing layers, whereas it is not retained on the OH-terminated regions of the surface. The use of ToF-SIMS was crucial for obtaining this information, as well as for monitoring each sequential step necessary for the preparation of the patterns.

  12. Final Activity Report: The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Trick, Charles Gordon [Western University

    2013-07-30

    Substantial increases in the concentrations of the stronger of two Fe(III) complexing organic ligand classes measured during the mesoscale Fe enrichment studies IronEx II and SOIREE appeared to sharply curtailed Fe availability to diatoms and thus limited the efficiency of carbon sequestration to the deep. Detailed observations during IronEx II (equatorial Pacific Ocean) and SOIREE (Southern Ocean –Pacific sector) indicate that the diatoms began re-experiencing Fe stress even though dissolved Fe concentrations remained elevated in the patch. This surprising outcome likely is related to the observed increased concentrations of strong Fe(III)-complexing ligands in seawater. Preliminary findings from other studies indicate that diatoms may not readily obtain Fe from these chemical species whereas Fe bound by strong ligands appears to support growth of cyanobacteria and nanoflagellates. The difficulty in assessing the likelihood of these changes with in-situ mesoscale experiments is the extended monitoring period needed to capture the long-term trajectory of the carbon cycle. A more detailed understanding of Fe complexing ligand effects on long-term ecosystem structure and carbon cycling is essential to ascertain not only the effect of Fe enrichment on short-term carbon sequestration in the oceans, but also the potential effect of Fe enrichment in modifying ecosystem structure and trajectory.

  13. Final Technical Report: The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Cochlan, William P.

    2008-06-13

    Substantial increases in the concentrations of the stronger of two Fe(III) complexing organic ligand classes measured during the mesoscale Fe enrichment studies IronEx II and SOIREE appeared to sharply curtailed Fe availability to diatoms and thus limited the efficiency of carbon sequestration to the deep. Detailed observations during IronEx II (equatorial Pacific Ocean) and SOIREE (Southern Ocean –Pacific sector) indicate that the diatoms began re-experiencing Fe stress even though dissolved Fe concentrations remained elevated in the patch. This surprising outcome likely is related to the observed increased concentrations of strong Fe(III)-complexing ligands in seawater. Preliminary findings from other studies indicate that diatoms may not readily obtain Fe from these chemical species whereas Fe bound by strong ligands appears to support growth of cyanobacteria and nanoflagellates. The difficulty in assessing the likelihood of these changes with in-situ mesoscale experiments is the extended monitoring period needed to capture the long-term trajectory of the carbon cycle. A more detailed understanding of Fe complexing ligand effects on long-term ecosystem structure and carbon cycling is essential to ascertain not only the effect of Fe enrichment on short-term carbon sequestration in the oceans, but also the potential effect of Fe enrichment in modifying ecosystem structure and trajectory.

  14. Efficacy, Tolerability, and Acceptability of Iron Hydroxide Polymaltose Complex versus Ferrous Sulfate: A Randomized Trial in Pediatric Patients with Iron Deficiency Anemia

    Directory of Open Access Journals (Sweden)

    Beril Yasa

    2011-01-01

    Full Text Available Iron polymaltose complex (IPC offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA were randomized to IPC once daily or ferrous sulfate twice daily, (both 5 mg iron/kg/day. Mean increases in Hb to months 1 and 4 with IPC were 1.2±0.9 g/dL and 2.3±1.3 g/dL, respectively, (both P=0.001 versus baseline and 1.8±1.7 g/dL and 3.0±2.3 g/dL with ferrous sulfate (both P=0.001 versus baseline (n.s. between groups. Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P=0.012. Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63±0.56 versus 2.14±0.75, P=0.001. Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability.

  15. Complex permeability and permittivity variation of carbonyl iron rubber in the frequency range of 2 to 18 GHz

    Directory of Open Access Journals (Sweden)

    Adriana Medeiros Gama

    2010-04-01

    Full Text Available The complex dielectric permittivity (e and magnetic permeability (m of Radar Absorbing Materials (RAM based on metallic magnetic particles (carbonyl iron particles embedded in a dielectric matrix (silicon rubber have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of carbonyl iron-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the frequency is analyzed. In a general way, the results show that e´ parameter shows a more significant variation among the evaluated parameters (e”, m”, m’. The comparison of dielectric and magnetic loss tangents (e”/e” and m”/m’, respectively shows more clearly the variation of both parameters (e and m according to the frequency. It is also observed that higher carbonyl iron content fractions favor both dielectric and magnetic loss tangents.

  16. Pro-Oxidant Activity of Amine-Pyridine-Based Iron Complexes Efficiently Kills Cancer and Cancer Stem-Like Cells.

    Science.gov (United States)

    González-Bártulos, Marta; Aceves-Luquero, Clara; Qualai, Jamal; Cussó, Olaf; Martínez, M Angeles; Fernández de Mattos, Silvia; Menéndez, Javier A; Villalonga, Priam; Costas, Miquel; Ribas, Xavi; Massaguer, Anna

    2015-01-01

    Differential redox homeostasis in normal and malignant cells suggests that pro-oxidant-induced upregulation of cellular reactive oxygen species (ROS) should selectively target cancer cells without compromising the viability of untransformed cells. Consequently, a pro-oxidant deviation well-tolerated by nonmalignant cells might rapidly reach a cell-death threshold in malignant cells already at a high setpoint of constitutive oxidative stress. To test this hypothesis, we took advantage of a selected number of amine-pyridine-based Fe(II) complexes that operate as efficient and robust oxidation catalysts of organic substrates upon reaction with peroxides. Five of these Fe(II)-complexes and the corresponding aminopyridine ligands were selected to evaluate their anticancer properties. We found that the iron complexes failed to display any relevant activity, while the corresponding ligands exhibited significant antiproliferative activity. Among the ligands, none of which were hemolytic, compounds 1, 2 and 5 were cytotoxic in the low micromolar range against a panel of molecularly diverse human cancer cell lines. Importantly, the cytotoxic activity profile of some compounds remained unaltered in epithelial-to-mesenchymal (EMT)-induced stable populations of cancer stem-like cells, which acquired resistance to the well-known ROS inducer doxorubicin. Compounds 1, 2 and 5 inhibited the clonogenicity of cancer cells and induced apoptotic cell death accompanied by caspase 3/7 activation. Flow cytometry analyses indicated that ligands were strong inducers of oxidative stress, leading to a 7-fold increase in intracellular ROS levels. ROS induction was associated with their ability to bind intracellular iron and generate active coordination complexes inside of cells. In contrast, extracellular complexation of iron inhibited the activity of the ligands. Iron complexes showed a high proficiency to cleave DNA through oxidative-dependent mechanisms, suggesting a likely mechanism of

  17. Slow magnetic relaxation and electron delocalization in an S = 9/2 iron(II/III) complex with two crystallographically inequivalent iron sites

    Science.gov (United States)

    Hazra, Susanta; Sasmal, Sujit; Fleck, Michel; Grandjean, Fernande; Sougrati, Moulay T.; Ghosh, Meenakshi; Harris, T. David; Bonville, Pierre; Long, Gary J.; Mohanta, Sasankasekhar

    2011-05-01

    The magnetic, electronic, and Mössbauer spectral properties of [Fe2L(μ-OAc)2]ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St = 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300 K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm-1 for an electron transfer parameter, B, of 950 cm-1, a zero-field uniaxial D9/2 parameter of -0.9(1) cm-1, and g = 1.95(5). In agreement with the presence of uniaxial magnetic anisotropy, ac susceptibility measurements reveal that 1 is a single-molecule magnet at low temperature with a single molecule magnetic effective relaxation barrier, Ueff, of 9.8 cm-1. At 5.25 K the Mössbauer spectra of 1 exhibit two spectral components, assigned to the two crystallographically inequivalent iron sites with a static effective hyperfine field; as the temperature increases from 7 to 310 K, the spectra exhibit increasingly rapid relaxation of the hyperfine field on the iron-57 Larmor precession time of 5 × 10-8 s. A fit of the temperature dependence of the average effective hyperfine field yields |D9/2| = 0.9 cm-1. An Arrhenius plot of the logarithm of the relaxation frequency between 5 and 85 K yields a relaxation barrier of 17 cm-1.

  18. Study on spin configuration in photoresponsive iron mixed-valence complexes by Mössbauer spectroscopy

    Science.gov (United States)

    Okazawa, A.; Yoshida, J.; Kida, N.; Kashima, I.; Murata, W.; Enomoto, M.; Kojima, N.

    2014-04-01

    We have investigated magnetic properties in a series of photoresponsive dithiooxalato (dto)-bridged iron mixed-valence complexes, (SP-R)[FeIIFeIII(dto)3] (SP-R = R-substituted pyridospiropyran cation; R = Me, Et, and Pr; abbreviated as 1 Me, 1 Et, and 1 Pr, respectively). As for our previous reports, 1 Me and 1 Et show two-step succeeding ferromagnetic transitions at T C = 25 & 8 K and 22 & 5 K, respectively. However, 1 Et has no hysteresis in the magnetic susceptibility, while 1 Me undergoes the charge transfer phase transition with thermal hysteresis around 75 K. To elucidate the two-step transitions of them, we measured 57Fe Mössbauer spectra of 1 Et. The spectra of FeII ( S = 2) and FeIII ( S = 1/2) in the HTP were observed in the magnetically ordered state as well as the paramagnetic state, and revealed that only HTP exists in a temperature range up to 5 K. The result is consistent with that of 1 Pr, where one ferromagnetic phase transition occurs at T C = 10 K. 57Fe Mössbauer spectroscopy is useful to clarify the origin of the succeeding magnetic transition for these systems.

  19. Polynuclear Iron-Oxo/Hydroxy Complexes of Ketoacidoximate Ligands: Synthesis, Structures and Conversion to Ferric Oxide

    KAUST Repository

    Davaasuren, Bambar

    2017-06-13

    The polynuclear iron-oxo/hydroxy complexes containing ketoacidoximate ligands described in this report are [Fe3(μ3-O){O2C-C(C6H5)=NOCH3}6(py)3] (1) (py=pyridine), [Fe2(μ3-O){O2C-C(CH2-C6H5)=NO}2(H2O)(CH3OH)]2 (2) and [{Fe(μ2-OH)(O2C-C(CH3)=NO)}(dmso)]6 (3) (dmso=dimethyl sulfoxide). 1–3 are isolated from the reaction of Fe(NO3)3⋅9H2O and in situ generated anions of ketoacidoximate ligand [(HO2C-C(R1)=NOR2), where R1=CH3, C6H5 and CH2-C6H5; R2=H or CH3] in H2O, followed by crystallization in donor solvents. 1–3 undergo thermal decomposition above 200 °C and form crystalline α-Fe2O3 at 600 °C.

  20. Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

    Directory of Open Access Journals (Sweden)

    David Porter

    2015-12-01

    Full Text Available Iron(II complexes of the tetradentate amines tris(2-pyridylmethylamine (TPA and N,N′-bis(2-pyridylmethyl-N,N′-dimethylethane-1,2-diamine (BPMEN are established catalysts of C–O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C–N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with either FeTPA (1 mol % or FeBPMEN (10 mol % converts cyclohexene to the allylic hydroxylamine (tert-butyl cyclohex-2-en-1-yl(hydroxycarbamate in moderate yields. Spectroscopic studies and trapping experiments suggest the reaction proceeds via a nitroso–ene mechanism, with involvement of a free N-Boc-nitroso intermediate. Asymmetric induction is not observed using the chiral tetramine ligand (+-(2R,2′R-1,1′-bis(2-pyridylmethyl-2,2′-bipyrrolidine ((R,R′-PDP.

  1. A mechanistic study and computational prediction of iron, cobalt and manganese cyclopentadienone complexes for hydrogenation of carbon dioxide.

    Science.gov (United States)

    Ge, Hongyu; Chen, Xiangyang; Yang, Xinzheng

    2016-10-13

    A series of cobalt and manganese cyclopentadienone complexes are proposed and examined computationally as promising catalysts for hydrogenation of CO 2 to formic acid with total free energies as low as 20.0 kcal mol -1 in aqueous solution. Density functional theory study of the newly designed cobalt and manganese complexes and experimentally reported iron cyclopentadienone complexes reveals a stepwise hydride transfer mechanism with a water or a methanol molecule assisted proton transfer for the cleavage of H 2 as the rate-determining step.

  2. Structural and spectroscopic characterization of five coordinate iron and cobalt bis(dithiolene)-trimethylphosphine complexes

    Science.gov (United States)

    Selby-Karney, Troy; Grossie, David A.; Arumugam, Kuppuswamy; Wright, Eyglo; Chandrasekaran, P.

    2017-08-01

    Heteroleptic bis(dithiolene)-phosphine iron and cobalt complexes [Fe(adt)2(PMe3)] (1) and [Co(adt)2(PMe3)] (2) (adt = para-anisyldithiolene) have been synthesized from corresponding bis(dithiolene) dimers [M2(adt)4]2 (M = Fe, Co) by reacting with excess PMe3 in dichloromethane. Solid-state structures of 1 and 2 have been determined by single crystal X-ray crystallography, and the dithiolene ligands Csbnd S (≈1.72 Å) and Csbnd C (≈1.37 Å) bond distances reveal the coordination of π-radical monoanionic dithiolene (adt•1-) ligands to metal centers. Intense low energy ligand-to-ligand-charge transfer (LLCT) absorption band (743 nm for 1; 905 nm for 2) in UV-vis spectra and characteristic ν(Cdbnd S•) (1168 cm-1 for 1; 1170 cm-1 for 2) in IR spectra affirms coordination of π-radical monoanionic dithiolenes to divalent metal ions. The cyclic voltammogram of 1 and 2 shows reversible oxidation and reduction waves attributed to MII → MIII + e- (+0.52 V for 1; +0.29 V for 2) and adt•1- + e- → adt2- (-0.63 V for 1; -0.46 V for 2) redox process respectively. Comprehensive structural and spectroscopic investigations conclude, [M2III(adt2-)2(adt•1-)2] → 2 [MII(adt•1-)2(PMe3)] intramolecular redox interplay during phosphine coordination induced cleavage of homoleptic bis(dithiolene) dimers to produce square pyramidal complexes.

  3. Uranium exploration target selection for proterozoic iron oxide/breccia complex type deposits in India

    International Nuclear Information System (INIS)

    Dwivedy, K.K.; Sinha, K.K.

    1997-01-01

    Multimetal iron oxide/breccia complex (IOBC) type deposits exemplified by Olympic Dam in Australia, fall under low grade, large tonnage deposits. A multidisciplinary integrated exploration programme consisting of airborne surveys, ground geological surveys, geophysical and geochemical investigations and exploratory drilling, supported adequately by the state of the art analytical facilities, data processing using various software and digital image processing has shown moderate success in the identification of target areas for this type of deposits in the Proterozoic terrains of India. Intracratonic, anorogenic, continental rift to continental margin environment have been identified in a very wide spectrum of rock associations. The genesis and evolution of such associations during the Middle Proterozoic period have been reviewed and applied for target selection in the (i) Son-Narmada rift valley zone; (ii) areas covered by Dongargarh Supergroup of rocks in Madhya Pradesh; (iii) areas exposing ferruginous breccia in the western part of the Singhbhum Shear Zone (SSZ) around Lotapahar; (iv) Siang Group of rocks in Arunachal Pradesh; (v) Crystalline rocks of Garo Hills around Anek; and (vi) Chhotanagpur Gneissic complex in the Bahia-Ulatutoli tract of Ranchi Plateau. Of theses six areas, the Son-Narmada rift area appears to be the most promising area for IOBC type deposits. Considering occurrences of the uranium anomalies near Meraraich, Kundabhati, Naktu and Kudar and positive favourability criteria observed in a wide variety of rocks spatially related to the rifts and shears, certain sectors in Son-Narmada rift zone have been identified as promising for intense subsurface exploration. 20 refs, 4 figs, 1 tab

  4. Measuring marine iron(III) complexes by CLE-AdSV

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.

    2005-01-01

    Iron(iii) speciation data, as determined by competitive ligand exchange?adsorptive stripping voltammetry (CLE-AdSV), is reconsidered in the light of the kinetic features of the measurement. The very large stability constants reported for iron(iii) in marine ecosystems are shown to be possibly due to

  5. Reply to Comments on Measuring marine iron(III) complexes by CLE-AdSV

    NARCIS (Netherlands)

    Town, R.M.; Leeuwen, van H.P.

    2005-01-01

    The interpretation of CLE-AdSV based iron(iii) speciation data for marine waters has been called into question in light of the kinetic features of the measurement. The implications of the re-think may have consequences for understanding iron biogeochemistry and its impact on ecosystem functioning.

  6. Extraction chromatographic separation of iron from complex liquid samples and the determination of 55Fe

    International Nuclear Information System (INIS)

    Grahek, Z.; Rozmaric Macefat, M.

    2006-01-01

    Iron separation is described from liquid samples with a high concentration of ions that enables simple determination of 55 Fe. One of the described methods consists of iron precipitation from a large volume seawater by sodium hydroxide and/or ammonium carbonate and separation from other elements (Ca, Sr, Cu, Mg, etc.) on a TRU column with 4M HCl or 8M HNO 3 . In the other procedure iron is separated directly from a mixture of seawater samples and HCl on a TRU column. In both methods, the iron recovery is almost 100%. After separation, 55 Fe is determined by counting with a liquid scintillation counter. The binding of Fe and Zn on TEVA, U/TEVA and TRU resins from seawater solutions of HCl and HNO 3 depends on the type of the resin, concentration of acid and other ions. Iron and zinc can be separated from seawater on a U/TEVA column with 2M HCl. (author)

  7. Regulation of Protein Function and Signaling by Reversible Cysteine S-Nitrosylation*

    Science.gov (United States)

    Gould, Neal; Doulias, Paschalis-Thomas; Tenopoulou, Margarita; Raju, Karthik; Ischiropoulos, Harry

    2013-01-01

    NO is a versatile free radical that mediates numerous biological functions within every major organ system. A molecular pathway by which NO accomplishes functional diversity is the selective modification of protein cysteine residues to form S-nitrosocysteine. This post-translational modification, S-nitrosylation, impacts protein function, stability, and location. Despite considerable advances with individual proteins, the in vivo biological chemistry, the structural elements that govern the selective S-nitrosylation of cysteine residues, and the potential overlap with other redox modifications are unknown. In this minireview, we explore the functional features of S-nitrosylation at the proteome level and the structural diversity of endogenously modified residues, and we discuss the potential overlap and complementation that may exist with other cysteine modifications. PMID:23861393

  8. Regulation of protein function and signaling by reversible cysteine S-nitrosylation.

    Science.gov (United States)

    Gould, Neal; Doulias, Paschalis-Thomas; Tenopoulou, Margarita; Raju, Karthik; Ischiropoulos, Harry

    2013-09-13

    NO is a versatile free radical that mediates numerous biological functions within every major organ system. A molecular pathway by which NO accomplishes functional diversity is the selective modification of protein cysteine residues to form S-nitrosocysteine. This post-translational modification, S-nitrosylation, impacts protein function, stability, and location. Despite considerable advances with individual proteins, the in vivo biological chemistry, the structural elements that govern the selective S-nitrosylation of cysteine residues, and the potential overlap with other redox modifications are unknown. In this minireview, we explore the functional features of S-nitrosylation at the proteome level and the structural diversity of endogenously modified residues, and we discuss the potential overlap and complementation that may exist with other cysteine modifications.

  9. Evaluation of umbilical cord mesenchymal stem cells labeling with superparamagnetic iron oxide nanoparticles coated with dextran and complexed with Poly-L-Lysine

    International Nuclear Information System (INIS)

    Sibov, Tatiana Tais; Mamani, Javier Bustamante; Pavon, Lorena Favaro; Cardenas, Walter Humberto; Gamarra, Lionel Fernel; Miyaki, Liza Aya Mabuchi; Marti, Luciana Cavalheiro; Sardinha, Luiz Roberto; Oliveira, Daniela Mara de

    2012-01-01

    Objective: The objective of this study was to evaluate the effect of the labeling of umbilical cord vein derived mesenchymal stem cells with superparamagnetic iron oxide nanoparticles coated with dextran and complexed to a non-viral transfector agent transfector poly-L-lysine. Methods: The labeling of mesenchymal stem cells was performed using the superparamagnetic iron oxide nanoparticles/dextran complexed and not complexed to poly-L-lysine. Superparamagnetic iron oxide nanoparticles/dextran was incubated with poly-L-lysine in an ultrasonic sonicator at 37 deg C for 10 minutes for complex formation superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine by electrostatic interaction. Then, the mesenchymal stem cells were incubated overnight with the complex superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine and superparamagnetic iron oxide nanoparticles/dextran. After the incubation period the mesenchymal stem cells were evaluated by internalization of the complex superparamagnetic iron oxide nanoparticles/dextran/polyL-lysine and superparamagnetic iron oxide nanoparticles/dextran by Prussian Blue stain. Cellular viability of labeled mesenchymal stem cells was evaluated by cellular proliferation assay using 5,6-carboxyfluorescein-succinimidyl ester method and apoptosis detection by Annexin V- Propidium Iodide assay. Results: mesenchymal stem cells labeled with superparamagnetic iron oxide nanoparticles/ dextran without poly-L-lysine not internalized efficiently the superparamagnetic iron oxide nanoparticles due to its low presence detected within cells. Mesenchymal stem cells labeled with the complex superparamagnetic iron oxide nanoparticles/dextran/polyL-lysine efficiently internalized the superparamagnetic iron oxide nanoparticles due to greater presence in the cells interior. The viability and apoptosis assays demonstrated that the mesenchymal stem cells labeled and not labeled respectively with the superparamagnetic iron oxide

  10. Antibacterial, Prooxidative and Genotoxic Activities of Gallic Acid and its Copper and Iron Complexes against Escherichia coli

    Directory of Open Access Journals (Sweden)

    JONATHAN M. BARCELO

    2014-12-01

    Full Text Available In this study, gallic acid and its complexes with aluminum and iron were investigated for their antibacterial, pro-oxidative, and genotoxic properties at alkaline pH. At 4.0μmol/mL, gallic acid displayed bacteriostatic property while aluminum-gallic acid and iron-gallic acid complexes showed bactericidal property against Escherichia coli ATCC 25922. A higher antibacterial activity was observed in the turbidimetric assay compared to the well-diffusion assay. The metal complexes of gallic acid also generated a higher concentration of malondialdehyde and hydrogen peroxide compared to gallic acid alone at > 0.50µmol/mL. Using the SOS response of the DNA repair-deficient Escherichia coli PQ37, the metal complexes of gallic acid resulted to a significantly higher SOS Induction Factors (ρ<0.01 at ≥0.25μmol/mL. In addition, gallic acid and its metal complexes decrease the cell surface hydrophobicity of E. coli ATCC 25922 in a dose-dependent manner. The present study suggests that the antibacterial property of gallic acid and its metal complexes against Escherichia coli was caused by its pro-oxidative and genotoxic properties. Since metals are involved in the synthesis of the metal complexes of gallic acid, further tests should be conducted to determine their stability and effects to human health.

  11. SNOSite: exploiting maximal dependence decomposition to identify cysteine S-nitrosylation with substrate site specificity.

    Directory of Open Access Journals (Sweden)

    Tzong-Yi Lee

    Full Text Available S-nitrosylation, the covalent attachment of a nitric oxide to (NO the sulfur atom of cysteine, is a selective and reversible protein post-translational modification (PTM that regulates protein activity, localization, and stability. Despite its implication in the regulation of protein functions and cell signaling, the substrate specificity of cysteine S-nitrosylation remains unknown. Based on a total of 586 experimentally identified S-nitrosylation sites from SNAP/L-cysteine-stimulated mouse endothelial cells, this work presents an informatics investigation on S-nitrosylation sites including structural factors such as the flanking amino acids composition, the accessible surface area (ASA and physicochemical properties, i.e. positive charge and side chain interaction parameter. Due to the difficulty to obtain the conserved motifs by conventional motif analysis, maximal dependence decomposition (MDD has been applied to obtain statistically significant conserved motifs. Support vector machine (SVM is applied to generate predictive model for each MDD-clustered motif. According to five-fold cross-validation, the MDD-clustered SVMs could achieve an accuracy of 0.902, and provides a promising performance in an independent test set. The effectiveness of the model was demonstrated on the correct identification of previously reported S-nitrosylation sites of Bos taurus dimethylarginine dimethylaminohydrolase 1 (DDAH1 and human hemoglobin subunit beta (HBB. Finally, the MDD-clustered model was adopted to construct an effective web-based tool, named SNOSite (http://csb.cse.yzu.edu.tw/SNOSite/, for identifying S-nitrosylation sites on the uncharacterized protein sequences.

  12. Iron and Prochlorococcus

    Science.gov (United States)

    2009-06-01

    facilitate iron transport, store iron, regulate iron homeostasis , and enable acclimation to low iron availability (Andrews et al, 2003). In...Bacterial iron homeostasis . FEMS Microbiology Reviews 27: 215-237. Barbeau K (2006) Photochemistry of Organic Iron(III) Complexing Ligands in Oceanic...Microbiology 145: 1473-1484. Moore JK, Doney SC, Lindsay K (2004) Upper ocean ecosystem dynamics and iron cycling in a global three-dimensional

  13. Catalysis and molecular magnetism of dinuclear iron(III) complexes with N-(2-pyridylmethyl)-iminodiethanol/-ate.

    Science.gov (United States)

    Shin, Jong Won; Bae, Jeong Mi; Kim, Cheal; Min, Kil Sik

    2014-03-14

    The reaction of N-(2-pyridylmethyl)iminodiethanol (H2pmide) and Fe(NO3)3·9H2O in MeOH led to the formation of a dimeric iron(III) complex, [(Hpmide)Fe(NO3)]2(NO3)2·2CH3OH (1). Its anion-exchanged form, [(pmide)Fe(N3)]2 (2), was prepared by the reaction of 1and NaN3 in MeOH, during which the Hpmide ligand of 1 was also deprotonated. These compounds were investigated by single crystal X-ray diffraction and magnetochemistry. In complex 1, one iron(III) ion was bonded with a mono-deprotonated Hpmide ligand and a nitrate ion. The two iron(III) ions within the dinuclear unit were connected by two ethoxy groups with an inversion center. In 2, one iron(III) ion was coordinated with a deprotonated pmide ligand and an azide ion. The Fe(pmide)(N3) unit was related by symmetry through an inversion center. Both 1 and 2 efficiently catalyzed the oxidation of a variety of alcohols under mild conditions. The oxidation mechanism was proposed to involve an Fe(IV)=O intermediate as the major reactive species and an Fe(V)=O intermediate as a minor oxidant. Evidence for this proposal was derived from reactivity and Hammett studies, KIE (kH/kD) values, and the use of MPPH (2-methyl-1-phenylprop-2-yl hydroperoxide) as a mechanistic probe. Both compounds had significant antiferromagnetic interactions between the iron(III) ions via the oxygen atoms. 1 showed a strong antiferromagnetic interaction within the Fe(III) dimer, while 2 had a weak antiferromagnetic coupling within the Fe(III) dimer.

  14. Nuclear inelastic scattering and density-functional-theory calculations on the understanding of the vibronic properties of polynuclear iron complexes

    International Nuclear Information System (INIS)

    Faus, Isabelle

    2015-01-01

    Transition metal complexes of 3d elements with an electronic configuration of d 4 to d 8 can show a temperature dependent spin transition. This process is called spin crossover (SCO) effect and describes the transition between two states, the low spin (LS) state and the high spin (HS) state. In the LS state the spin is as low as possible, caused by none or a minimal number of unpaired electrons. In the HS state the spin is as high as possible with a maximal number of unpaired electrons. Because of this bistability, SCO materials are promising candidates for innovative molecular storage devices. Directly related to the SCO effect is the cooperativity, which specifies the interaction of metal centers between molecules (intermolecular cooperativity) or in a molecule (intramolecular cooperativity). Cooperativity is of vital importance for the switching behavior of SCO complexes with broad hysteresis. Therefore, three dinuclear SCO complexes which show a varying degree of cooperativity due to different geometries of their bridging ligands were investigated. By means of nuclear inelastic scattering (NIS), it could be clarified whether it is possible to find intramolecular cooperative effects in the vibrational patterns of these complexes. With corresponding density functional theory (DFT) calculations, it was possible for all of the dinuclear complexes to correlate the experimental NIS bands to the corresponding molecular vibrational modes. In the LS-LS or HS-HS state of the three complexes two modes exist lying energetically close together, which show a similar movement of the whole complex, with only a difference in the movement of the iron atoms. Thereby, the irons are moving either in the same or in the opposite direction. For complexes with a high degree of cooperativity there are nearly exclusively small energy shifts between this kind of nearly twofold energetically degenerated modes (ΔE <7 cm -1 ), for the complex with a low degree of cooperativity there are

  15. A Chemical Composition Survey of the Iron-complex Globular Cluster NGC 6273 (M19)

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Christian I.; Caldwell, Nelson [Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, MS-15, Cambridge, MA 02138 (United States); Rich, R. Michael [Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547 (United States); Mateo, Mario [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Bailey, John I. III [Leiden Observatory, Leiden University, P.O. Box 9513, 2300RA Leiden (Netherlands); Clarkson, William I. [Department of Natural Sciences, University of Michigan–Dearborn, 4901 Evergreen Road, Dearborn, MI 48128 (United States); Olszewski, Edward W. [Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Walker, Matthew G., E-mail: cjohnson@cfa.harvard.edu, E-mail: ncaldwell@cfa.harvard.edu, E-mail: rmr@astro.ucla.edu, E-mail: mmateo@umich.edu, E-mail: baileyji@strw.leidenuniv.nl, E-mail: wiclarks@umich.edu, E-mail: eolszewski@as.arizona.edu, E-mail: mgwalker@andrew.cmu.edu [McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)

    2017-02-20

    Recent observations have shown that a growing number of the most massive Galactic globular clusters contain multiple populations of stars with different [Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been recognized as a member of this “iron-complex” cluster class, and we provide here a chemical and kinematic analysis of >300 red giant branch and asymptotic giant branch member stars using high-resolution spectra obtained with the Magellan –M2FS and VLT–FLAMES instruments. Multiple lines of evidence indicate that NGC 6273 possesses an intrinsic metallicity spread that ranges from about [Fe/H] = −2 to −1 dex, and may include at least three populations with different [Fe/H] values. The three populations identified here contain separate first (Na/Al-poor) and second (Na/Al-rich) generation stars, but a Mg–Al anti-correlation may only be present in stars with [Fe/H] ≳ −1.65. The strong correlation between [La/Eu] and [Fe/H] suggests that the s-process must have dominated the heavy element enrichment at higher metallicities. A small group of stars with low [ α /Fe] is identified and may have been accreted from a former surrounding field star population. The cluster’s large abundance variations are coupled with a complex, extended, and multimodal blue horizontal branch (HB). The HB morphology and chemical abundances suggest that NGC 6273 may have an origin that is similar to ω Cen and M54.

  16. Iron allocation in leaves of Fe-deficient cucumber plants fed with natural Fe complexes.

    Science.gov (United States)

    Zanin, Laura; Tomasi, Nicola; Rizzardo, Cecilia; Gottardi, Stefano; Terzano, Roberto; Alfeld, Matthias; Janssens, Koen; De Nobili, Maria; Mimmo, Tanja; Cesco, Stefano

    2015-05-01

    Iron (Fe) sources available for plants in the rhizospheric solution are mainly a mixture of complexes between Fe and organic ligands, including phytosiderophores (PS) and water-extractable humic substances (WEHS). In comparison with the other Fe sources, Fe-WEHS are more efficiently used by plants, and experimental evidences show that Fe translocation contributes to this better response. On the other hand, very little is known on the mechanisms involved in Fe allocation in leaves. In this work, physiological and molecular processes involved in Fe distribution in leaves of Fe-deficient Cucumis sativus supplied with Fe-PS or Fe-WEHS up to 5 days were studied combining different techniques, such as radiochemical experiments, synchrotron micro X-ray fluorescence, real-time reverse transcription polymerase chain reaction and in situ hybridization. In Fe-WEHS-fed plants, Fe was rapidly (1 day) allocated into the leaf veins, and after 5 days, Fe was completely transferred into interveinal cells; moreover, the amount of accumulated Fe was much higher than with Fe-PS. This redistribution in Fe-WEHS plants was associated with an upregulation of genes encoding a ferric(III) -chelate reductase (FRO), a Fe(2+) transporter (IRT1) and a natural resistance-associated macrophage protein (NRAMP). The localization of FRO and IRT1 transcripts next to the midveins, beside that of NRAMP in the interveinal area, may suggest a rapid and efficient response induced by the presence of Fe-WEHS in the extra-radical solution for the allocation in leaves of high amounts of Fe. In conclusion, Fe is more efficiently used when chelated to WEHS than PS and seems to involve Fe distribution and gene regulation of Fe acquisition mechanisms operating in leaves. © 2014 Scandinavian Plant Physiology Society.

  17. Direct evidence for a coordination-insertion mechanism of ethylene oligomerization catalysed by neutral 2,6-bisiminopyridine iron monoalkyl complexes

    OpenAIRE

    Cartes, M. Ángeles; Rodríguez-Delgado, Antonio; Palma, Pilar; Sánchez, Luis J.; Cámpora, Juan; CSIC - Unidad de Recursos de Información Científica para la Investigación (URICI)

    2014-01-01

    1H NMR studies on ethylene oligomerization catalysed by the neutral monoalkyl complex [Fe(Me)(iPrBIP)] allow direct observation of alkyl iron intermediates as well as reversible ethylene coordination to the metal center, providing for the first time experimental evidence for a coordination-insertion mechanism of iron-catalysed ethylene upgrade reactions. © 2014 the Partner Organisations.

  18. GSNOR Deficiency Enhances In Situ Skeletal Muscle Strength, Fatigue Resistance, and RyR1 S-Nitrosylation Without Impacting Mitochondrial Content and Activity

    Science.gov (United States)

    Moon, Younghye; Cao, Yenong; Zhu, Jingjing; Xu, Yuanyuan; Balkan, Wayne; Buys, Emmanuel S.; Diaz, Francisca; Kerrick, W. Glenn; Hare, Joshua M.

    2017-01-01

    Abstract Aim: Nitric oxide (NO) plays important, but incompletely defined roles in skeletal muscle. NO exerts its regulatory effects partly though S-nitrosylation, which is balanced by denitrosylation by enzymes such as S-nitrosoglutathione reductase (GSNOR), whose functions in skeletal muscle remain to be fully deciphered. Results: GSNOR null (GSNOR−/−) tibialis anterior (TA) muscles showed normal growth and were stronger and more fatigue resistant than controls in situ. However, GSNOR−/− lumbrical muscles showed normal contractility and Ca2+ handling in vitro, suggesting important differences in GSNOR function between muscles or between in vitro and in situ environments. GSNOR−/− TA muscles exhibited normal mitochondrial content, and capillary densities, but reduced type IIA fiber content. GSNOR inhibition did not impact mitochondrial respiratory complex I, III, or IV activities. These findings argue that enhanced GSNOR−/− TA contractility is not driven by changes in mitochondrial content or activity, fiber type, or blood vessel density. However, loss of GSNOR led to RyR1 hypernitrosylation, which is believed to increase muscle force output under physiological conditions. cGMP synthesis by soluble guanylate cyclase (sGC) was decreased in resting GSNOR−/− muscle and was more responsive to agonist (DETANO, BAY 41, and BAY 58) stimulation, suggesting that GSNOR modulates cGMP production in skeletal muscle. Innovation: GSNOR may act as a “brake” on skeletal muscle contractile performance under physiological conditions by modulating nitrosylation/denitrosylation balance. Conclusions: GSNOR may play important roles in skeletal muscle contractility, RyR1 S-nitrosylation, fiber type specification, and sGC activity. Antioxid. Redox Signal. 26, 165–181. PMID:27412893

  19. The contribution of N₂O₃ to the cytotoxicity of the nitric oxide donor DETA/NO: an emerging role for S-nitrosylation.

    Science.gov (United States)

    Ali, Ahlam A; Coulter, Jonathan A; Ogle, Claire H; Migaud, Marie M; Hirst, David G; Robson, Tracy; McCarthy, Helen O

    2013-03-28

    The relationship between the biological activity of NO and its chemistry is complex. The objectives of this study were to investigate the influence of oxygen tension on the cytotoxicity of the NO• donor DETA/NO and to determine the effects of oxygen tension on the key RNS (reactive nitrogen species) responsible for any subsequent toxicity. The findings presented in this study indicate that the DETA/NO-mediated cytotoxic effects were enhanced under hypoxic conditions. Further investigations revealed that neither ONOO⁻ (peroxynitrite) nor nitroxyl was generated. Fluorimetric analysis in the presence of scavengers suggest for the first time that another RNS, dinitrogen trioxide may be responsible for the cytotoxicity with DETA/NO. Results showed destabilization of HIF (hypoxia inducible factor)-1α and depletion of GSH levels following the treatment with DETA/NO under hypoxia, which renders cells more susceptible to DETA/NO cytotoxicity, and could account for another mechanism of DETA/NO cytotoxicity under hypoxia. In addition, there was significant accumulation of nuclear p53, which showed that p53 itself might be a target for S-nitrosylation following the treatment with DETA/NO. Both the intrinsic apoptotic pathway and the Fas extrinsic apoptotic pathway were also activated. Finally, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) is another important S-nitrosylated protein that may possibly play a key role in DETA/NO-mediated apoptosis and cytotoxicity. Therefore this study elucidates further mechanisms of DETA/NO mediated cytotoxicity with respect to S-nitrosylation that is emerging as a key player in the signalling and detection of DETA/NO-modified proteins in the tumour microenvironment.

  20. Characterization of a Novel Polysaccharide-Iron(III) Complex and Its Anti-Anemia and Nonspecific Immune Regulating Activities.

    Science.gov (United States)

    Zhang, Yun; Ma, Fanyi; Zhu, Jinhua; Du, Zuliang; Zhao, Ying-Yong; Liu, Xiuhua

    2017-01-01

    Dioscorea opposita Thunb is the famous food and traditional medicine in China and it was rich in polysaccharides. Polysaccharides of Dioscorea Opposita Thunb possess immunoregulatory activity, free radical scavenging activity and anti-diabetic activity. A novel polysaccharide- iron(III) complex (CYPIC) was synthesized by using crude polysaccharide extracted from Dioscorea opposita Thunb. The component, structure, morphology and molecular weights of CYPIC were analysed, and the anti-anemia, acute toxicity and nonspecific immune regulating activities of CYPIC were assayed. The results showed that CYPIC could increase red blood cell count (RBC), hemoglobin (Hb), hematocrit (HCT), thymus and spleen index of mice with iron deficiency anemia (IDA). Although the structure and deeper mechanisms of CYPIC should be further studied, CYPIC has the potential to be used as an iron supplement for the treatment of iron deficiency anemia. The large scale industrial production was suggested due to the simple preparation processing of CYPIC. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. Determination of Non-Transferrin Bound Iron, Transferrin Bound Iron, Drug Bound Iron and Total Iron in Serum in a Rats after IV Administration of Sodium Ferric Gluconate Complex by Simple Ultrafiltration Inductively Coupled Plasma Mass Spectrometric Detection

    Directory of Open Access Journals (Sweden)

    Murali K. Matta

    2018-02-01

    Full Text Available A rapid, sensitive and specific ultrafiltration inductively-coupled plasma mass spectrometry method was developed and validated for the quantification of non-transferrin bound iron (NTBI, transferrin bound iron (TBI, drug bound iron (DI and total iron (TI in the same rat serum sample after intravenous (IV administration of iron gluconate nanoparticles in sucrose solution (Ferrlecit®. Ultrafiltration with a 30 kDa molecular cut-off filter was used for sample cleanup. Different elution solvents were used to separate each form of iron from sample serum. Isolated fractions were subjected to inductively-coupled mass spectrometric analysis after microwave digestion in 4% nitric acid. The reproducibility of the method was evaluated by precision and accuracy. The calibration curve demonstrated linearity from 5–500 ng/mL with a regression (r2 of more than 0.998. This method was effectively implemented to quantify rat pharmacokinetic study samples after intravenous administration of Ferrlecit®. The method was successfully applied to a pharmacokinetic (PK study of Ferrlecit in rats. The colloidal iron followed first order kinetics with half-life of 2.2 h and reached background or pre-dose levels after 12 h post-dosing. The drug shown a clearance of 0.31 mL/min/kg and volume of distribution of 0.05 L/kg. 19.4 ± 2.4 mL/h/kg.

  2. THE CELLULAR TRANSFORMATION OF INJECTED COLLOIDAL IRON COMPLEXES INTO FERRITIN AND HEMOSIDERIN IN EXPERIMENTAL ANIMALS

    Science.gov (United States)

    Richter, Goetz W.

    1959-01-01

    As revealed by electron microscopy and electron diffraction, the physical state of ferric hydroxide micelles contained in iron-dextran, saccharated iron oxide, and hydrous ferric oxide ("ferric hydroxide") differs notably from the state of the ferric hydroxide in ferritin or hemosiderin. By virtue of this difference one can trace the intracellular transformation of colloidal iron, administered parenterally, into ferritin and hemosiderin. One hour after intraperitoneal injection of iron-dextran or saccharated iron oxide into mice, characteristic deposits were present in splenic macrophages, in sinusoidal endothelial cells of spleen and liver, and in vascular endothelial cells of various renal capillaries. Four hours after injection, small numbers of ferritin molecules were identifiable about intracellular aggregates of injected iron compounds; and by the 6th day, ferritin was abundant in close proximity to deposits of injected iron compounds. The latter were frequently situated in cytoplasmic vesicles delimited by single membranes. These vesicles were most frequently found in tissue obtained during the first 6 days after injection; and in certain of the vesicles ferritin molecules surrounded closely packed aggregates of injected material. Much unchanged ferric hydroxide was still present in macrophages and vascular endothelial cells 3 to 4 weeks after injection. While electron microscopy left no doubt about the identity of injected ferric hydroxide on the one hand, and of ferritin or hemosiderin on the other, histochemical tests for iron failed in this respect. Precipitation of ferric hydroxide (hydrous ferric oxide) from stabilized colloidal dispersions of iron-dextran was brought about in vitro by incubation with minced mouse tissue (e.g. liver), but not by incubation with mouse serum or blood. Subcutaneous injections of hydrous gel of ferric oxide into mice initially produced localized extracellular precipitates. Most of the material was still extracellular 16

  3. Formation, surface characterization, and electrocatalytic application of self-assembled monolayer films of tetra-substituted manganese, iron, and cobalt benzylthio phthalocyanine complexes

    CSIR Research Space (South Africa)

    Akinbulu, IA

    2011-10-01

    Full Text Available Molecular thin films of manganese (SAM-2), iron (SAM-3), and cobalt (SAM-4) phthalocyanine complexes, non-peripherally tetra-substituted with benzylmercapto, were formed on polycrystalline gold disc electrode by selfassembly technique. Surface...

  4. Laboratory Investigation of Complex Conductivity and Magnetic Susceptibility on Natural Iron Oxide Coated Sand

    Science.gov (United States)

    Wang, C.; Slater, L. D.; Day-Lewis, F. D.; Briggs, M. A.

    2017-12-01

    Redox reactions occurring at the oxic/anoxic interface where groundwater discharges to surface water commonly result in iron oxide deposition that coats sediment grains. With relatively large total surface area, these iron oxide coated sediments serve as a sink for sorption of dissolved contaminants, although this sink may be temporary if redox conditions fluctuate with varied flow conditions. Characterization of the distribution of iron oxides in streambed sediments could provide valuable understanding of biogeochemical reactions and the ability of a natural system to sorb contaminants. Towards developing a field methodology, we conducted laboratory spectral induced polarization (SIP) and magnetic susceptibility (MS) measurements on natural iron oxide coated sand (Fe-sand) with grain sizes ranging from 0.3 to 2.0 mm in order to assess the sensitivity of these measurements to iron oxides in sediments. The Fe-sand was also sorted by sieving into various grain sizes to study the impact of grain size on the polarization mechanisms. The unsorted Fe-sand saturated with 0.01 S/m NaCl solution exhibited a distinct phase response ( > 4 mrad) in the frequency range from 0.001 to 100 Hz whereas regular silica sand was characterized by a phase response less than 1 mrad under the same conditions. The presence of iron oxide substantially increased MS (3.08×10-3 SI) over that of regular sand ( < 10-5 SI). An increase of both phase peak and relaxation time was found with increasing grain size of the sorted Fe-sand. Laboratory results demonstrated that SIP and MS may be well suited to mapping the distribution of iron oxides in streambed sediments associated with anoxic groundwater discharge.

  5. S-Nitrosylation-Mediated Redox Transcriptional Switch Modulates Neurogenesis and Neuronal Cell Death

    Directory of Open Access Journals (Sweden)

    Shu-ichi Okamoto

    2014-07-01

    Full Text Available Redox-mediated posttranslational modifications represent a molecular switch that controls major mechanisms of cell function. Nitric oxide (NO can mediate redox reactions via S-nitrosylation, representing transfer of an NO group to a critical protein thiol. NO is known to modulate neurogenesis and neuronal survival in various brain regions in disparate neurodegenerative conditions. However, a unifying molecular mechanism linking these phenomena remains unknown. Here, we report that S-nitrosylation of myocyte enhancer factor 2 (MEF2 transcription factors acts as a redox switch to inhibit both neurogenesis and neuronal survival. Structure-based analysis reveals that MEF2 dimerization creates a pocket, facilitating S-nitrosylation at an evolutionally conserved cysteine residue in the DNA binding domain. S-Nitrosylation disrupts MEF2-DNA binding and transcriptional activity, leading to impaired neurogenesis and survival in vitro and in vivo. Our data define a molecular switch whereby redox-mediated posttranslational modification controls both neurogenesis and neurodegeneration via a single transcriptional signaling cascade.

  6. Effect of protein S-nitrosylation on autolysis and catalytic ability of μ-calpain.

    Science.gov (United States)

    Liu, Rui; Li, Yupin; Wang, Mengqin; Zhou, Guanghong; Zhang, Wangang

    2016-12-15

    The effect of S-nitrosylation on the autolysis and catalytic ability of μ-calpain in vitro in the presence of 50μM Ca(2 +) was investigated. μ-Calpain was incubated with different concentrations of nitric oxide donor S-nitrosoglutathione (GSNO) and subsequently reacted with purified myofibrils. Results showed that the amount of 80kDa μ-calpain subunit significantly decreased as GSNO increased from 0 to 300μM, but increases of GSNO to 300, 500 and 1000μM did not result in further inhibition. The catalytic ability of nitrosylated μ-calpain to degrade titin, nebulin, troponin-T and desmin was significantly reduced when the GSNO concentration was higher than 300μM. The cysteine residues of μ-calpain at positions 49, 351, 384, and 592 in the catalytic subunit and at 142 in small subunit were S-nitrosylated, which could be responsible for decreased μ-calpain activity. Thus, S-nitrosylation can negatively regulate the activation of μ-calpain resulting in decreased proteolytic ability on myofibrils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Synthesis of Magnetic Ultrafine Particles from a Ternary Gaseous Mixture Involving Cobalt Tricarbonyl Nitrosyl

    Czech Academy of Sciences Publication Activity Database

    Morita, H.; Sakano, H.; Murafa, Nataliya; Šubrt, Jan

    2014-01-01

    Roč. 27, č. 46 (2014), s. 477-483 ISSN 0914-9244 Institutional support: RVO:61388980 Keywords : gas phase photochemical reaction * magnetic ultrafine particle * cobalt tricarbonyl nitrosyl * tetraethylgermane * propenyltrimethylsilane Subject RIV: CA - Inorganic Chemistry Impact factor: 1.055, year: 2014

  8. Magnetic Control of Macromolecular Conformations in Supramolecular Anionic Polysaccharide-Iron Complexes.

    Science.gov (United States)

    Schefer, Larissa; Bulant, Ariane; Zeder, Christophe; Saha, Abhijit; Mezzenga, Raffaele

    2015-11-02

    The anionic iota carrageenan polysaccharide is enriched with Fe(II) and Fe(III) by ion exchange against FeSO4 and FeCl3 . With divalent iron, portions of polymer chains undergo a secondary structure transition from random coils to single helices. The single-chain macromolecular conformations can be manipulated by an external magnetic field: upon exposure to 1.1 T, the helical portions exhibit 1.5-fold stiffening and 1.1-fold stretching, whereas the coil conformations respond much less as a result of lower contents of condensed iron ions. Along with the coil-helix transition, the trivalent iron triggers the formation of superstructures. The applicability of iron-enriched iota carrageenan as functional ingredient for food fortification is tested by free Fe(2+) and Fe(3+) contents, respectively, with the most promising iota-Fe(III) yielding 53% of bound iron, which is due to the superstructures, where the ferric ions are chelated by the supramolecularly self-assembled polymer host. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Dioxygenation Reaction of a Cobalt-Nitrosyl: Putative Formation of a Cobalt-Peroxynitrite via a {CoIII(NO)(O2-)} Intermediate.

    Science.gov (United States)

    Gogoi, Kuldeep; Saha, Soumen; Mondal, Baishakhi; Deka, Hemanta; Ghosh, Somnath; Mondal, Biplab

    2017-12-04

    A cobalt-nitrosyl complex, [(BPI)Co(NO)(OAc)], 1 {BPI = 1,3-bis(2'-pyridylimino)isoindol} was prepared and characterized. Structural characterization revealed that the cobalt center has a distorted square pyramidal geometry with the NO group coordinated from the apical position in a bent fashion. The addition of dioxygen (O 2 ) to the dichloromethane solution of complex 1 resulted in the formation of nitro complex, [(BPI)Co(NO 2 )(OAc)], 2. It was characterized structurally. Kinetic studies suggested the involvement of an associative mechanism. FT-IR spectroscopic studies suggested the formation of the intermediate 1a [(BPI)Co III (NO)(O 2 - )(OAc)] in the reaction. The intermediate 1a decomposed to complex 2 via a presumed peroxynitrite intermediate which was implicated by its characteristic phenol ring nitration reaction.

  10. Effect of ozone on ruthenium species in alkaline medium. Pt. II. Oxidation of pentahydroxo nitrosyl ruthenate(II) ion RuNO(OH)52-

    International Nuclear Information System (INIS)

    Floquet, S.; Eysseric, C.

    2006-01-01

    Oxidation of the nitrosyl ruthenium complex RuNO(OH) 5 2- has been carried out in sodium hydroxide solutions in contact with a gas flow containing ozone. The RuNO(OH) 5 2- complex is converted successively into ruthenate and perruthenate ions. An empirical kinetic rate law for the first step has been determined and was shown to depend on concentrations of (i) the ruthenium complex, (ii) the hydroxide ions and (iii) ozone concentration in the gas flow. The second step of the reaction, corresponding to the perruthenate ion formation, shows a complex mechanism and four competing reactions have been proposed to represent it. The influences on the second step kinetics of several parameters such as ozone or hydroxide concentrations or the conditions of the gas-liquid exchange area are also qualitatively discussed. (orig.)

  11. Effect of ozone on ruthenium species in alkaline medium. Pt. II. Oxidation of pentahydroxo nitrosyl ruthenate(II) ion RuNO(OH){sub 5}{sup 2-}

    Energy Technology Data Exchange (ETDEWEB)

    Floquet, S. [Commissariat a l' Energie Atomique (CEA/Valrho), Bagnols-sur-Ceze (France); Inst. Lavoisier, IREM UMR 8637, Univ. de Versailles Saint-Quentin, Versailles (France); Eysseric, C. [Commissariat a l' Energie Atomique (CEA/Valrho), Bagnols-sur-Ceze (France)

    2006-07-01

    Oxidation of the nitrosyl ruthenium complex RuNO(OH){sub 5}{sup 2-} has been carried out in sodium hydroxide solutions in contact with a gas flow containing ozone. The RuNO(OH){sub 5}{sup 2-} complex is converted successively into ruthenate and perruthenate ions. An empirical kinetic rate law for the first step has been determined and was shown to depend on concentrations of (i) the ruthenium complex, (ii) the hydroxide ions and (iii) ozone concentration in the gas flow. The second step of the reaction, corresponding to the perruthenate ion formation, shows a complex mechanism and four competing reactions have been proposed to represent it. The influences on the second step kinetics of several parameters such as ozone or hydroxide concentrations or the conditions of the gas-liquid exchange area are also qualitatively discussed. (orig.)

  12. EFFECT OF ALLOYING ON TEMPERATURE OF TRANSFORMATION «PEARLITE – AUSTENITE» IN COMPLEX-ALLOYED WHITE CAST IRONS

    Directory of Open Access Journals (Sweden)

    T. V. Pastukhova

    2014-11-01

    Full Text Available Purpose. Pearlite is not accepted in the microstructure of wear resistant steels and cast irons. To prevent the pearlite by means of appropriate selection of mode of quenching requires the knowledge of the temperature of the critical points Ac1 and Ac3 for various steels and cast irons. Purpose of work is determine the effect of V (5-10% and Cr (up to 9% on the temperature range of the phase-structural transformation "pearlite®austenite in the complex-alloyed V-Cr-Mn-Ni white cast irons with spheroidal vanadium carbides. Methodology. Nine Mg-treated cast irons smelted in laboratory furnace were used for investigation. The metallographic and optical dilatometric analysis methods as well as energy-dispersive spectroscopy were used. Findings. It is shown that in irons studied the critical point Ac1 is in a temperature range from 710-780 °C (lower limit up to 730-850 °C (upper limit. The data on the concentrations of chromium and vanadium in a matrix of iron are presented, the regression equation describing the effect of vanadium and chromium on the temperature limits of the transformation «pearlite ® austenite» are obtained. Originality. It is shown that increase the chromium content leads to growth of lower and upper limits of the temperature interval of transformation "pearlite ® austenite"; vanadium increases only the upper limit of the range. It was found that the effect of chromium on the critical point Ac1 is attributed to its solubility in the metallic matrix (concentration of Cr in the austenite reaches 7%; vanadium, due to its slight dissolution in the matrix (vanadium content does not exceed 1.75%, affects the critical point indirectly by increasing of chromium concentration in the matrix due to enhanced carbon sequestration in VC carbides. Practical value. The temperature ranges of heating for quenching of V-Cr-Mn-Ni cast irons with spheroidal vanadium carbides, which provides the formation of austenitic-martensitic matrix without

  13. Vanadium-bearing titaniferous iron ores from the Rooiwater, Usushwana, Mambula, Kaffirskraal, and the Trompsburg igneous complexes

    International Nuclear Information System (INIS)

    Reynolds, A.M.

    1979-01-01

    The mineralogy and chemistry of some vanadium-bearing titaniferous iron ores from a number of smaller South African basic intrusions are reported, and an assessment is given of the potential of these ores for use as raw materials in the production of iron, high-titania slag, and vanadium pentoxide. The ores from each complex can be distinguised readily on the basis of their chemical composition and textural relations. The Rooiwater Complex represents the most promising area. It contains two layers of titaniferous magnetite, each approximately 8 m thick, in the eastern part, the lowest seam being chemically similar to the economically important main layer of titaniferous magnetite in the Bushveld Complex. The ores are silicate-poor and consist largely of multi-phase titaniferous-magnetite grains containing modified ilmenite and pleonaste micro-intergrowths. The coarse grain size of these ores favours beneficiation, and they can be partially treated to yield ilmenite concentrates and low-titania magnetite fractions in which the content of vanadium pentoxide is higher than that in the original ores. The Mambula ores are silicate-rich and would require extensive beneficiation. The Kaffirskraal ores consist of multi-phase grains of titaniferous magnetite containing crystallographically oriented ilmenite, ulvospinel, and pleonaste micro-intergrowths. Minor coarser-grained ilmenite is also present. The Usushwana ores are texturaly similar but contain abundant lamellar ilmenite in place of the ulvospinel. The ores from these two complexes cannot be beneficiated by conventional ore-dressing techniques, and would require direct metallurgical treatment for the recovery of iron, titania, and vanadium pentoxide [af

  14. Iron(III) and copper(II) complexes of trans-bis(ferrocenyl)porphyrin ...

    Indian Academy of Sciences (India)

    ,10-bisferrocenyl-15,20- bisphenylporphyrin (2−); M = Fe(III)Cl .... Mo Kα radiation (λ = 0.71073 Å) while SAINT software8 was used for data integration .... iron moves towards the porphyrin mean plane in. Figure 4. Out-of-plane displacements ...

  15. Iron(II,III)-polyphenol complex nanoparticles derived from green tea with remarkable ecotoxicological impact

    Science.gov (United States)

    There are several greener methods exist to synthesize zero–valent iron nanoparticles (nZVI) using different bio-based reducing agents. Although their useful properties in degradation of organic dyes, chlorinated organics, or arsenic have been described earlier, their characteriza...

  16. Deciphering Fur transcriptional regulatory network highlights its complex role beyond iron metabolism in Escherichia coli

    DEFF Research Database (Denmark)

    Seo, Sang Woo; Kim, Donghyuk; Latif, Haythem

    2014-01-01

    The ferric uptake regulator (Fur) plays a critical role in the transcriptional regulation of iron metabolism. However, the full regulatory potential of Fur remains undefined. Here we comprehensively reconstruct the Fur transcriptional regulatory network in Escherichia coli K-12 MG1655 in response...

  17. Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

    KAUST Repository

    Haslinger, Stefan

    2014-11-03

    This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

  18. Interaction of Iron II Complexes with B-DNA. Insights from Molecular Modeling, Spectroscopy and Cellular Biology.

    Directory of Open Access Journals (Sweden)

    Hugo eGattuso

    2015-12-01

    Full Text Available We report the characterization of the interaction between B-DNA and three terpyridin iron II complexes. Relatively long time-scale molecular dynamics is used in order to characterize the stable interaction modes. By means of molecular modeling and UV-vis spectroscopy, we prove that they may lead to stable interactions with the DNA duplex. Furthermore, the presence of larger π-conjugated moieties also leads to the appearance of intercalation binding mode. Non-covalent stabilizing interactions between the iron complexes and the DNA are also characterized and evidenced by the analysis of the gradient of the electronic density. Finally, the structural deformations induced on the DNA in the different binding modes are also evidenced. The synthesis and chemical characterization of the three complexes is reported, as well as their absorption spectra in presence of DNA duplexes to prove the interaction with DNA. Finally, their effects on human cell cultures have also been evidenced to further enlighten their biological effects.

  19. Analysis of the structure of poly-3-hydroxybutyrate ultrathin fibers modified with iron (III) complex with tetraphenylporphyrin

    Science.gov (United States)

    Olkhov, A. A.; Karpova, S. G.; Lobanov, A. V.; Tyubaeva, P. M.; Artemov, N. S.; Iordansky, A. L.

    2017-12-01

    In the treatment of many infectious diseases and cancer, transdermal systems based on solid polymer matrices or gels containing functional substances with antiseptic (antibacterial) properties are often used. One of the most promising types of matrices with antiseptic properties are the ones of nano- and microfiber-bonded cloth obtained by electrospinning based on biopolymer poly(3-hydroxybutyrate). The present work investigates the effects of iron (III) complex with tetraphenylporphyrin and the influence on the geometry, crystalline order and molecular dynamics in the intercrystalline (amorphous phase) of ultrathin PHB fibers.

  20. Efficient hydrogen liberation from formic acid catalyzed by a well-defined iron pincer complex under mild conditions.

    Science.gov (United States)

    Zell, Thomas; Butschke, Burkhard; Ben-David, Yehoshoa; Milstein, David

    2013-06-17

    Hydrogen liberation: An attractive approach to reversible hydrogen storage applications is based on the decomposition of formic acid. The efficient and selective hydrogen liberation from formic acid is catalyzed by an iron pincer complex in the presence of trialkylamine. Turnover frequencies up to 836 h⁻¹ and turnover numbers up to 100,000 were achieved at 40 °C. A mechanism including well-defined intermediates is suggested on the basis of experimental and computational data. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Analysis of Heme Iron Coordination in DGCR8: The Heme-Binding Component of the Microprocessor Complex.

    Science.gov (United States)

    Girvan, Hazel M; Bradley, Justin M; Cheesman, Myles R; Kincaid, James R; Liu, Yilin; Czarnecki, Kazimierz; Fisher, Karl; Leys, David; Rigby, Stephen E J; Munro, Andrew W

    2016-09-13

    DGCR8 is the RNA-binding partner of the nuclease Drosha. Their complex (the "Microprocessor") is essential for processing of long, primary microRNAs (pri-miRNAs) in the nucleus. Binding of heme to DGCR8 is essential for pri-miRNA processing. On the basis of the split Soret ultraviolet-visible (UV-vis) spectrum of ferric DGCR8, bis-thiolate sulfur (cysteinate, Cys(-)) heme iron coordination of DGCR8 heme iron was proposed. We have characterized DGCR8 heme ligation using the Δ276 DGCR8 variant and combined electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), electron nuclear double resonance, resonance Raman, and electronic absorption spectroscopy. These studies indicate DGCR8 bis-Cys heme iron ligation, with conversion from bis-thiolate (Cys(-)/Cys(-)) axial coordination in ferric DGCR8 to bis-thiol (CysH/CysH) coordination in ferrous DGCR8. Pri-miRNA binding does not perturb ferric DGCR8's optical spectrum, consistent with the axial ligand environment being separated from the substrate-binding site. UV-vis absorption spectra of the Fe(II) and Fe(II)-CO forms indicate discrete species exhibiting peaks with absorption coefficients substantially larger than those for ferric DGCR8 and that previously reported for a ferrous form of DGCR8. Electron-nuclear double resonance spectroscopy data exclude histidine or water as axial ligands for ferric DGCR8 and favor bis-thiolate coordination in this form. UV-vis MCD and near-infrared MCD provide data consistent with this conclusion. UV-vis MCD data for ferrous DGCR8 reveal features consistent with bis-thiol heme iron coordination, and resonance Raman data for the ferrous-CO form are consistent with a thiol ligand trans to the CO. These studies support retention of DGCR8 cysteine coordination upon reduction, a conclusion distinct from those of previous studies of a different ferrous DGCR8 isoform.

  2. Selective activation of C-F and C-H bonds with iron complexes, the relevant mechanism study by DFT calculations and study on the chemical properties of hydrido iron complex.

    Science.gov (United States)

    Xu, Xiaofeng; Jia, Jiong; Sun, Hongjian; Liu, Yuxia; Xu, Wengang; Shi, Yujie; Zhang, Dongju; Li, Xiaoyan

    2013-03-14

    The reactions of (2,6-difluorophenyl)phenylmethanone (2,6-F(2)C(6)H(3)-C(=O)-C(6)H(5)) (1) and (2,6-difluorophenyl)phenylmethanimine (2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(5)) (3) with Fe(PMe(3))(4) afforded different selective C-F/C-H bond activation products. The reaction of 1 with Fe(PMe(3))(4) gave rise to bis-chelate iron(II) complex [C(6)H(5)-C(=O)-3-FC(6)H(3))Fe(PMe(3))](2) (2) via C-F bond activation. The reaction of 3 with Fe(PMe(3))(4) delivered chelate hydrido iron(II) complex 2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(4))Fe(H)(PMe(3))(3) (4) through C-H bond activation. The DFT calculations show the detailed elementary steps of the mechanism of formation of hydrido complex 4 and indicate 4 is the kinetically preferred product. Complex 4 reacted with HCl, CH(3)Br and CH(3)I delivered the chelate iron halides (2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(4))Fe(PMe(3))(3)X (X = Cl (5); Br (6); I (7)). A ligand (PMe(3)) replacement by CO of 4 was observed giving (2,6-F(2)C(6)H(3)-C(=NH)-C(6)H(4))Fe(H)(CO)(PMe(3))(2) (8). The chelate ligand exchange occurred through the reaction of 4 with salicylaldehydes. The reaction of 4 with Me(3)SiC[triple bond, length as m-dash]CH afforded (2,6-F(2)C(6)H(3)-C([double bond, length as m-dash]N)-C(6)H(5))Fe(C≡C-SiMe(3))(PMe(3))(3) (11). A reaction mechanism from 4 to 11 was discussed with the support of IR monitoring. The molecular structures of complexes 2, 4, 6, 7, 10 and 11 were determined by X-ray diffraction.

  3. Evaluation of the production, composition and aluminum and iron complexation of algogenic organic matter

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Martin; Klouček, Ondřej; Pivokonská, Lenka

    2006-01-01

    Roč. 40, č. 16 (2006), s. 3045-3052 ISSN 0043-1354 R&D Projects: GA AV ČR KJB200600501 Institutional research plan: CEZ:AV0Z20600510 Keywords : affinity chromatography * algogenic organic matter * aluminum and iron coagulants * extracellular organic matter * molecular weight fractionation * intracellular organic matter Subject RIV: BK - Fluid Dynamics Impact factor: 2.459, year: 2006

  4. Reconstitution of active mycobacterial binuclear iron monooxygenase complex in Escherichia coli.

    Science.gov (United States)

    Furuya, Toshiki; Hayashi, Mika; Kino, Kuniki

    2013-10-01

    Bacterial binuclear iron monooxygenases play numerous physiological roles in oxidative metabolism. Monooxygenases of this type found in actinomycetes also catalyze various useful reactions and have attracted much attention as oxidation biocatalysts. However, difficulties in expressing these multicomponent monooxygenases in heterologous hosts, particularly in Escherichia coli, have hampered the development of engineered oxidation biocatalysts. Here, we describe a strategy to functionally express the mycobacterial binuclear iron monooxygenase MimABCD in Escherichia coli. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the mimABCD gene expression in E. coli revealed that the oxygenase components MimA and MimC were insoluble. Furthermore, although the reductase MimB was expressed at a low level in the soluble fraction of E. coli cells, a band corresponding to the coupling protein MimD was not evident. This situation rendered the transformed E. coli cells inactive. We found that the following factors are important for functional expression of MimABCD in E. coli: coexpression of the specific chaperonin MimG, which caused MimA and MimC to be soluble in E. coli cells, and the optimization of the mimD nucleotide sequence, which led to efficient expression of this gene product. These two remedies enabled this multicomponent monooxygenase to be actively expressed in E. coli. The strategy described here should be generally applicable to the E. coli expression of other actinomycetous binuclear iron monooxygenases and related enzymes and will accelerate the development of engineered oxidation biocatalysts for industrial processes.

  5. Metal pollution around an iron smelter complex in northern Norway at different modes of operation

    International Nuclear Information System (INIS)

    Steinnes, E.; Sjoebakk, T.E.; Frontas'eva, M.V.; Varskog, P.

    2003-01-01

    The moss biomonitoring technique was employed to study the atmospheric deposition in and around the town of Mo i Rana, northern Norway, before and after closing an iron smelter and establishing alternative ferrous metal industries. Samples of Hylocomium splendens were collected from the same sites in 1989 and 1993. A combination of instrumental neutron activation analysis (INAA) and atomic absorption spectrometry was used to obtain data for 38 elements in these moss samples, and the analytical data were subjected to factor analysis. In general, the deposition was higher when the iron smelter was still in operation, in particular for Fe and for many elements normally associated with crustal matter. For Cr there was a substantially increased deposition due to the operation of a new ferrochrome smelter. Also for Ni and Au an increased deposition was observed, whereas for metals such as Mn, Co, Ag, Sb, and W there was no appreciable change. INAA proved to be a powerful tool for this kind of study. The regional distribution of pollutants was strongly dependent on the local topography. Samples of natural surface soils collected simultaneously with the first moss series showed clear signs of contamination with a number of metals from atmospheric deposition. The approach described in this work could be advantageously used to study atmospheric deposition of heavy metals around iron smelters in Russia and elsewhere

  6. Oxidation of Cyclohexane by Molecular Oxygen Photoassisted by meso-Tetraarylporphyrin Iron(III)-Hydroxo Complexes.

    Science.gov (United States)

    Maldotti, A.; Bartocci, C.; Varani, G.; Molinari, A.; Battioni, P.; Mansuy, D.

    1996-02-28

    The photochemical and photocatalytic properties of iron meso-tetraarylporphyrins bearing an OH(-) axial ligand and different substituents in the beta-positions of the porphyrin ring are reported. Irradiation (lambda = 365 nm) in the absence of dioxygen leads to the reduction of Fe(III) to Fe(II) with the formation of OH(*) radicals. Substituents at the pyrrole beta-positions are found to markedly affect the photoreduction quantum yields. Under aerobic conditions, this photoreaction can induce the subsequent oxidation of cyclohexane to cyclohexanone and cyclohexanol by O(2) itself. The process occurs under mild conditions (22 degrees C; 760 Torr of O(2)) and without the consumption of a reducing agent. The polarity of the solvent and the nature of the porphyrin ring have a remarkable effect on the selectivity of the photooxidation process, likely controlling the cleavage of O-O bonds of possible iron peroxoalkyl intermediates. In particular, in pure cyclohexane, oxidation occurs with the selective formation of cyclohexanone; in contrast, in dichloromethane/cyclohexane mixed solvent, the main oxidation product is cyclohexanol. Phenyl-tert-butylnitrone (pbn) has been found to quench the radical chain autooxidation of the substrate thus increasing the yield of cyclohexanol. This becomes the only oxidation product when iron 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin hydroxide (Fe(III)(TDCPP)(OH)) is used as photocatalyst.

  7. Separation of iron and cobalt using 59Fe and 60Co by dialysis of polyvinylpyrrolidone-metal complexes: A greener approach

    International Nuclear Information System (INIS)

    Lahiri, Susanta; Sarkar, Soumi

    2007-01-01

    An environmentally benign method to separate iron and cobalt has been developed using a safe chemical, polyvinylpyrrolidone (PVP). The method involves dialysis of PVP-Fe and PVP-Co complexes against triple-distilled water. 59 Fe and 60 Co were used as radioactive tracers of iron and cobalt throughout the experiment. No other chemicals are required for clean separation of cobalt from iron. The optimum condition for separation has been obtained at pH 5 using 10% aqueous solution of PVP. The method is applicable from trace scale to macro-scale. Very high separation factors have been obtained

  8. Study of occupational health impact of atmospheric pollution on exposed workers at an iron and steel complex by using neutron activation analysis of scalp hair

    International Nuclear Information System (INIS)

    Chai, Z.F.; Qian, Q.F.; Feng, X.Q.; Zhang, P.Q.; Liu, N.Q.; Feng, W.Y.

    2004-01-01

    The occupational health impact of atmospheric pollution on exposed workers at one iron and steel complex was studied by instrumental neutron activation analysis of workers' hair samples and medical examination. The experimental results indicate that there is a positive correlation between the high inhalation amounts of iron and other trace elements by the exposed workers and the symptom of their high blood pressure and hypoglycemia, which implies that the atmospheric environment polluted by iron and steel industry has an adverse health impact on the exposed workers. The measures to relieve and abate the occupational diseases caused by air-borne particulate matter should be taken. (author)

  9. Iron(II) tris(3-bromo-1,10-phenanthroline) complex:synthesis, crystal structure and electropolymerization

    CERN Document Server

    Lee, K J; Lee, S S; Lee, B Y

    2002-01-01

    The complex of iron(II) tris(3-Br-phen)(3-Br-phen; 3-bromo-1,10-phenanthroline) was prepared as a precursor of electropolymerization and the crystal structure of [Fe(3-Br-phen) sub 3](PF sub 6) sub 2 centre dot CH sub 3 CN with a distorted octahedral geometry has been investigated. The reductive electropolymerization of [Fe(3-Br-phen) sub 3] sup 2 sup + complex onto the surface of a glassy carbon electrode and indium tin oxide (ITO) optically transparent electrode were performed in acetonitrile at room temperature. Thin film of poly-[Fe(3-Br-phen) sub 3] sup 2 sup + formed was adherent, electroactive and stably deposited on a glassy carbon disk electrode. The thin metallopolymeric film formed was also confirmed by absorption spectroscopy.

  10. Temperature dependence of Q-band electron paramagnetic resonance spectra of nitrosyl heme proteins

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Marco; Wajnberg, Eliane; Bemski, George

    1997-11-01

    The Q-band (35 GHz) electron paramagnetic resonance (EPR) spectra of nitrosyl hemoglobin (Hb N O) and nitrosyl myoglobin (Mb NO) were studied as a function of temperature between 19 K and 200 K. The spectra of both heme proteins show classes of variations as a function of temperature. The first one has previously been associated with the existence of two paramagnetic species, one with rhombic and the other with axial symmetry. The second one manifests itself in changes in the g-factors and linewidths of each species. These changes are correlated with the conformational substates model and associate the variations of g-values with changes in the angle of the N(his)-Fe-N (NO) bond in the rhombic species and with changes in the distance between Fe and N of the proximal (F8) histidine in the axial species. (author) 24 refs., 6 figs.

  11. INTERACTION OF IRON(II MIXED-LIGAND COMPLEXES WITH DNA: BASE-PAIR SPECIFICITY AND THERMAL DENATURATION STUDIES

    Directory of Open Access Journals (Sweden)

    Mudasir Mudasir

    2010-06-01

    Full Text Available A research about base-pair specificity of the DNA binding of [Fe(phen3]2+, [Fe(phen2(dip]2+ and [Fe(phen(dip2]2+ complexes and the effect of calf-thymus DNA (ct-DNA binding of these metal complexes on thermal denaturation of ct-DNA has been carried out. This research is intended to evaluate the preferential binding of the complexes to the sequence of DNA (A-T or G-C sequence and to investigate the binding strength and mode upon their interaction with DNA. Base-pair specificity of the DNA binding of the complexes was determined by comparing the equilibrium binding constant (Kb of each complex to polysynthetic DNA that contain only A-T or G-C sequence. The Kb value of the interaction was determined by spectrophotometric titration and thermal denaturation temperature (Tm was determined by monitoring the absorbance of the mixture solution of each complex and ct-DNA at λ =260 nm as temperature was elevated in the range of 25 - 100 oC. Results of the study show that in general all iron(II complexes studied exhibit a base-pair specificity in their DNA binding to prefer the relatively facile A-T sequence as compared to the G-C one. The thermal denaturation experiments have demonstrated that Fe(phen3]2+ and [Fe(phen2(dip]2+ interact weakly with double helical DNA via electrostatic interaction as indicated by insignificant changes in melting temperature, whereas [Fe(phen2(dip]2+  most probably binds to DNA in mixed modes of interaction, i.e.: intercalation and electrostatic interaction. This conclusion is based on the fact that the binding of [Fe(phen2(dip]2+ to ct-DNA moderately increase the Tm value of ct- DNA   Keywords: DNA Binding, mixed-ligand complexes

  12. S-nitrosylation of surfactant protein-D controls inflammatory function.

    Directory of Open Access Journals (Sweden)

    Chang-Jiang Guo

    2008-11-01

    Full Text Available The pulmonary collectins, surfactant proteins A and D (SP-A and SP-D have been implicated in the regulation of the innate immune system within the lung. In particular, SP-D appears to have both pro- and anti-inflammatory signaling functions. At present, the molecular mechanisms involved in switching between these functions remain unclear. SP-D differs in its quaternary structure from SP-A and the other members of the collectin family, such as C1q, in that it forms large multimers held together by the N-terminal domain, rather than aligning the triple helix domains in the traditional "bunch of flowers" arrangement. There are two cysteine residues within the hydrophobic N terminus of SP-D that are critical for multimer assembly and have been proposed to be involved in stabilizing disulfide bonds. Here we show that these cysteines exist within the reduced state in dodecameric SP-D and form a specific target for S-nitrosylation both in vitro and by endogenous, pulmonary derived nitric oxide (NO within a rodent acute lung injury model. S-nitrosylation is becoming increasingly recognized as an important post-translational modification with signaling consequences. The formation of S-nitrosothiol (SNO-SP-D both in vivo and in vitro results in a disruption of SP-D multimers such that trimers become evident. SNO-SP-D but not SP-D, either dodecameric or trimeric, is chemoattractive for macrophages and induces p38 MAPK phosphorylation. The signaling capacity of SNO-SP-D appears to be mediated by binding to calreticulin/CD91. We propose that NO controls the dichotomous nature of this pulmonary collectin and that posttranslational modification by S-nitrosylation causes quaternary structural alterations in SP-D, causing it to switch its inflammatory signaling role. This represents new insight into both the regulation of protein function by S-nitrosylation and NO's role in innate immunity.

  13. Examination of Alternaria alternata mutagenicity and effects of nitrosylation using the Ames Salmonella test.

    Science.gov (United States)

    Schrader, T J; Cherry, W; Soper, K; Langlois, I; Vijay, H M

    2001-01-01

    Molds of the genus Alternaria are common food pathogens responsible for the spoilage of fruits, vegetables, grains, and nuts. Although consumption of Alternaria alternata-contaminated foodstuffs has been implicated in an elevated incidence of esophageal carcinogenesis, the mutagenic potencies of several A. alternata toxins seem unable to account for the levels of activity found using crude mycelial extracts. In this study, the mutagenic effects of nitrosylation were examined with the major Alternaria metabolites Altenuene (ALT), Alternariol (AOH), Alternariol Monomethyl Ether (AME), Altertoxin I (ATX I), Tentoxin (TENT), Tenuazonic Acid (TA), and Radicinin (RAD) using the Ames Salmonella strains TA98 and TA100. In the absence of nitrosylation, ATX I was mutagenic when tested from 1 to 100 microg/plate in TA98 with rat liver S9 for activation, while AOH and ATX I were weakly mutagenic +/- S9 in TA100. Incubation with nitrite generally increased mutagenic potencies with ATX I strongly mutagenic +/- S9 in both TA98 and TA100, while ALT, AOH, AME, and RAD responses were enhanced in TA100 + S9. However, subsequent examination of three extracts made from A. alternata culture broth, acetone-washed mycelia, and the acetone washes showed a different mutagenic response with both broth and acetone washes directly mutagenic in TA98 and TA100 but with a reduced response + S9. The acetone-washed mycelial extract was found to have the lowest mutagenic activity of the three extracts tested. Nitrosylation had little effect on the mutagenicity of any of the extracts. Thus, while nitrosylation increases the mutagenicity of ATX I, and to a lesser extent that of several other Alternaria toxins, the results demonstrate that Alternaria produces a major mutagenic activity with a S. typhimurium response different from that found with the purified toxins. Efforts are currently underway to chemically identify this mutagenic species. Published 2001 Wiley-Liss, Inc.

  14. Dissecting plant iron homeostasis under short and long-term iron fluctuations

    DEFF Research Database (Denmark)

    Shirvanehdeh, Behrooz Darbani; Briat, Jean-Francois; Holm, Preben Bach

    2013-01-01

    A wealth of information on the different aspects of iron homeostasis in plants has been obtained during the last decade. However, there is no clear road-map integrating the relationships between the various components. The principal aim of the current review is to fill this gap. In this context we...... discuss the lack of low affinity iron uptake mechanisms in plants, the utilization of a different uptake mechanism by graminaceous plants compared to the others, as well as the roles of riboflavin, ferritin isoforms, nitric oxide, nitrosylation, heme, aconitase, and vacuolar pH. Cross-homeostasis between...... elements is also considered, with a specific emphasis on the relationship between iron homeostasis and phosphorus and copper deficiencies. As the environment is a crucial parameter for modulating plant responses, we also highlight how diurnal fluctuations govern iron metabolism. Evolutionary aspects...

  15. Metal Pollution Around an Iron Smelter Complex in Northern Norway at Different Modes of Operation

    CERN Document Server

    Steinnes, E; Eidhammer-Sjobakk, T; Varskog, P

    2003-01-01

    The moss biomonitoring technique was employed to study the atmospheric deposition in and around the town of Mo i Rana, northern Norway, before and after closing an iron smelter and establishing alternative ferrous metal industries. Samples of Hylocomium splendens were collected from the same sites in 1989 and 1993. A combination of instrumental neutron activation analysis (INAA) and atomic absorption spectrometry was used to obtain data for 38 elements in these moss samples, and the analytical data were subjected to factor analysis. In general, the deposition was higher when the iron smelter was still in operation, in particular for Fe and for many elements normally associated with crustal matter. For Cr there was a substantially increased deposition due to the operation of a new ferrochrome smelter. Also for Ni and Au an increased deposition was observed, whereas for metals such as Mn, Co, Ag, Sb, and W there was no appreciable change. INAA proved to be a powerful tool for this kind of study. The regional di...

  16. May the thyroid gland and thyroperoxidase participate in nitrosylation of serum proteins and sporadic Parkinson's disease?

    Science.gov (United States)

    Fernández, Emilio; García-Moreno, José-Manuel; Martín de Pablos, Angel; Chacón, José

    2014-11-20

    The research group has detected nitrosative stress and a singular version of nitrosylated serum α-synuclein in serum of Parkinson's disease (PD) patients. Dysfunction of the thyroid gland has been proposed to be linked to this disease. The aim of the study was to know if the thyroid gland is involved in idiopathic PD and nitrosative stress. We studied 50 patients (early and advanced disease patients), 35 controls, and 6 subjects with thyroidectomy. Clinical characteristics, serum thyroperoxidase levels, and 3-nitrotyrosine proteins were analyzed. Enzyme-linked immunosorbent assay and immunoblotting methods were employed. The findings indicated that the prevalence of two thyroid dysfunctions (hyper- or hypothyroidism) was not found to be different in patients relative to controls. However, the levels of the enzyme thyroperoxidase were found to be elevated in early disease patients (pdisease subjects, and these levels were negatively correlated with serum 3-nitrotyrosine proteins (pthyroid gland and thyroperoxidase participate in nitrosylation of serum proteins and they could influence Parkinsonian nitrosative stress as well as nitrosylation of serum α-synuclein, a potentially pathogenic factor.

  17. Synthesis and Characterization of Tc(I) Carbonyl Nitrosyl Species Relevant to the Hanford Tank Waste: FY 2016 Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Gabriel B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chatterjee, Sayandev [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Levitskaia, Tatiana G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Martin, Thibaut J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wall, Nathalie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Walter, Eric D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-11-24

    Among long-lived radioactive constituents in the Hanford tank waste, Tc presents a unique challenge in that it exists predominantly in the liquid phase, generally in the anionic form of pertechnetate, TcO4-, which is highly volatile at low-activity waste (LAW) vitrification melter temperatures and mobile in the Hanford site’s subsurface environment. The complex behavior of Tc under storage, treatment, and immobilization conditions significantly affects its management options, which to-date remain uncertain. In strongly alkaline environments, Tc exists as pertechnetate, TcO4- (oxidation state +7), and in the reduced forms (oxidation state < +7) collectively known as non-pertechnetate species. Pertechnetate is a well-characterized, anionic Tc species that can be removed from LAW by anion exchange or solvent extraction methods. There is no definitive information on the origin of the non-pertechnetate Tc species, nor is there a comprehensive description of their composition and behavior. It has been recently proposed that the non-pertechnetate species can comprise Tc(I) metal center and carbonyl or mixed carbonyl nitrosyl ligands stabilizing low-valent Tc. Recent work by our group has significantly expanded this previous work, generating a series of Tc(I) carbonyl compounds and demonstrating that they can be generated from reduction of TcO4- in the simulated Hanford tank waste in presence of CO at elevated temperature (Levitskaia et al. 2014). These results are consistent with the previous proposal that [Tc(CO)3]+ species can be present in the Hanford tank waste and suggest that the low Tc(I) oxidation state is stabilized by the π-accepting ability of the CO ligands. The continuation work has been initiated to develop model Tc carbonyl nitrosyl compounds and investigate their potential presence in the Hanford tank wastes. This report summarizes our to-date results.

  18. Siderophile element systematics of IAB complex iron meteorites: New insights into the formation of an enigmatic group

    Science.gov (United States)

    Worsham, Emily A.; Bermingham, Katherine R.; Walker, Richard J.

    2016-09-01

    Siderophile trace element abundances and the 187Re-187Os isotopic systematics of the metal phases of 58 IAB complex iron meteorites were determined in order to investigate formation processes and how meteorites within chemical subgroups may be related. Close adherence of 187Re-187Os isotopic data of most IAB iron meteorites to a primordial isochron indicates that the siderophile elements of most members of the complex remained closed to elemental disturbance soon after formation. Minor, presumably late-stage open-system behavior, however, is observed in some members of the sLM, sLH, sHL, and sHH subgroups. The new siderophile element abundance data are consistent with the findings of prior studies suggesting that the IAB subgroups cannot be related to one another by any known crystallization process. Equilibrium crystallization, coupled with crystal segregation, solid-liquid mixing, and subsequent fractional crystallization can account for the siderophile element variations among meteorites within the IAB main group (MG). The data for the sLM subgroup are consistent with equilibrium crystallization, combined with crystal segregation and mixing. By contrast, the limited fractionation of siderophile elements within the sLL subgroup is consistent with metal extraction from a chondritic source with little subsequent processing. The limited data for the other subgroups were insufficient to draw robust conclusions about crystallization processes involved in their formation. Collectively, multiple formational processes are represented in the IAB complex, and modeling results suggest that fractional crystallization within the MG may have been a more significant process than has been previously recognized.

  19. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  20. Divergent Coordination Chemistry: Parallel Synthesis of [2×2] Iron(II) Grid-Complex Tauto-Conformers.

    Science.gov (United States)

    Schäfer, Bernhard; Greisch, Jean-François; Faus, Isabelle; Bodenstein, Tilmann; Šalitroš, Ivan; Fuhr, Olaf; Fink, Karin; Schünemann, Volker; Kappes, Manfred M; Ruben, Mario

    2016-08-26

    The coordination of iron(II) ions by a homoditopic ligand L with two tridentate chelates leads to the tautomerism-driven emergence of complexity, with isomeric tetramers and trimers as the coordination products. The structures of the two dominant [Fe(II) 4 L4 ](8+) complexes were determined by X-ray diffraction, and the distinctness of the products was confirmed by ion-mobility mass spectrometry. Moreover, these two isomers display contrasting magnetic properties (Fe(II) spin crossover vs. a blocked Fe(II) high-spin state). These results demonstrate how the coordination of a metal ion to a ligand that can undergo tautomerization can increase, at a higher hierarchical level, complexity, here expressed by the formation of isomeric molecular assemblies with distinct physical properties. Such results are of importance for improving our understanding of the emergence of complexity in chemistry and biology. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  1. Catalysts of the oxidation of water to molecular oxygen based on binuclear iron(III) complexes and other transition-metal compounds

    Energy Technology Data Exchange (ETDEWEB)

    Elizarova, G.L.; Matvienko, L.G.; Parmon, V.N.; Zamaraev, K.I.

    1979-12-01

    The authors have found that dimeric dimine complexes of iron (III) and also complexes of some other transition metals are catalytically active in the following reaction: 4ML/sub 3//sup 3 +/ + 2H/sub 2/O ..-->.. 4ML/sub 3//sup 2 +/ + 0/sub 2/ + 4H/sup +/. The dimine complexes have the general formula ML/sub 3//sup 3 +/, where L is 1, 10-phenanthroline or 2,2'-dipyridyl.

  2. Peroxynitrite Toxicity in Escherichia coli K12 Elicits Expression of Oxidative Stress Responses and Protein Nitration and Nitrosylation*

    Science.gov (United States)

    McLean, Samantha; Bowman, Lesley A. H.; Sanguinetti, Guido; Read, Robert C.; Poole, Robert K.

    2010-01-01

    Peroxynitrite is formed in macrophages by the diffusion-limited reaction of superoxide and nitric oxide. This highly reactive species is thought to contribute to bacterial killing by interaction with diverse targets and nitration of protein tyrosines. This work presents for the first time a comprehensive analysis of transcriptional responses to peroxynitrite under tightly controlled chemostat growth conditions. Up-regulation of the cysteine biosynthesis pathway and an increase in S-nitrosothiol levels suggest S-nitrosylation to be a consequence of peroxynitrite exposure. Genes involved in the assembly/repair of iron-sulfur clusters also show enhanced transcription. Unexpectedly, arginine biosynthesis gene transcription levels were also elevated after treatment with peroxynitrite. Analysis of the negative regulator for these genes, ArgR, showed that post-translational nitration of tyrosine residues within this protein is responsible for its degradation in vitro. Further up-regulation was seen in oxidative stress response genes, including katG and ahpCF. However, genes known to be up-regulated by nitric oxide and nitrosating agents (e.g. hmp and norVW) were unaffected. Probabilistic modeling of the transcriptomic data identified five altered transcription factors in response to peroxynitrite exposure, including OxyR and ArgR. Hydrogen peroxide can be present as a contaminant in commercially available peroxynitrite preparations. Transcriptomic analysis of cells treated with hydrogen peroxide alone also revealed up-regulation of oxidative stress response genes but not of many other genes that are up-regulated by peroxynitrite. Thus, the cellular responses to peroxynitrite and hydrogen peroxide are distinct. PMID:20427277

  3. Order of Activity of Nitrogen, Iron Oxide, and FeNx Complexes towards Oxygen Reduction in Alkaline Medium.

    Science.gov (United States)

    Zhu, Yansong; Zhang, Bingsen; Wang, Da-Wei; Su, Dang Sheng

    2015-12-07

    In alkaline medium, it seems that both metal-free and iron-containing carbon-based catalysts, such as nitrogen-doped nanocarbon materials, FeOx -doped carbon, and Fe/N/C catalysts, are active for the oxygen reduction reaction (ORR). However, the order of activity of these different active compositions has not been clearly determined. Herein, we synthesized nitrogen-doped carbon black (NCB), Fe3 O4 /CB, Fe3 O4 /NCB, and FeN4 /CB. Through the systematic study of the ORR catalytic activity of these four catalysts in alkaline solution, we confirmed the difference in the catalytic activity and catalytic mechanism for nitrogen, iron oxides, and Fe-N complexes, respectively. In metal-free NCB, nitrogen can improve the ORR catalytic activity with a four-electron pathway. Fe3 O4 /CB catalyst did not exhibit improved activity over that of NCB owing to the poor conductivity and spinel structure of Fe3 O4 . However, FeN4 coordination compounds as the active sites showed excellent ORR catalytic activity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Evaluation of umbilical cord mesenchymal stem cell labeling with superparamagnetic iron oxide nanoparticles coated with dextran and complexed with Poly-L-lysine

    Directory of Open Access Journals (Sweden)

    Tatiana Taís Sibov

    2012-06-01

    Full Text Available Objective: The objective of this study was to evaluate the effect of thelabeling of umbilical cord vein derived mesenchymal stem cells withsuperparamagnetic iron oxide nanoparticles coated with dextran andcomplexed to a non-viral transfector agent transfector poly-L-lysine.Methods: The labeling of mesenchymal stem cells was performedusing the superparamagnetic iron oxide nanoparticles/dextrancomplexed and not complexed to poly-L-lysine. Superparamagneticiron oxide nanoparticles/dextran was incubated with poly-L-lysine inan ultrasonic sonicator at 37°C for 10 minutes for complex formationsuperparamagnetic iron oxide nanoparticles/dextran/poly-L-lysineby electrostatic interaction. Then, the mesenchymal stem cellswere incubated overnight with the complex superparamagnetic ironoxide nanoparticles/dextran/poly-L-lysine and superparamagneticiron oxide nanoparticles/dextran. After the incubation period themesenchymal stem cells were evaluated by internalization of thecomplex superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine and superparamagnetic iron oxide nanoparticles/dextran byPrussian Blue stain. Cellular viability of labeled mesenchymal stemcells was evaluated by cellular proliferation assay using 5,6-carboxyfluorescein-succinimidyl ester method and apoptosis detectionby Annexin V- Propidium Iodide assay. Results: mesenchymalstem cells labeled with superparamagnetic iron oxide nanoparticles/dextran without poly-L-lysine not internalized efficiently thesuperparamagnetic iron oxide nanoparticles due to its low presencedetected within cells. Mesenchymal stem cells labeled with thecomplex superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine efficiently internalized the superparamagnetic iron oxidenanoparticles due to greater presence in the cells interior. The viabilityand apoptosis assays demonstrated that the mesenchymal stemcells labeled and not labeled respectively with the superparamagneticiron oxide nanoparticles

  5. Comparison of early gastrointestinal tract and liver toxicity of the originator iron polymaltose complex (IPC) and an IPC similar preparation in non-anemic rats.

    Science.gov (United States)

    Toblli, Jorge E; Cao, Gabriel; Angerosa, Margarita

    2012-08-01

    The originator iron polymaltose complex (Maltofer®, IPC, Vifor International, St. Gallen, Switzerland) has been used for over 30 years to treat iron deficiency anemia. Its physico-chemical properties allow for a controlled release of iron, a property which translates into low toxicity and good gastrointestinal (GI) tolerability of the drug compared to the commonly used ferrous salts. A variety of different iron polymaltose complex similars are commercially available with varying structures and, thus, different efficacy and toxicity compared to IPC. In this study, the median lethal dose, the GI tract and liver toxicity of an IPC similar (Vitalix®, IPCSVITA, Laboratorios Roemmers, Buenos Aires, Argentina) were compared with those of IPC in healthy rats. The median lethal dose of IPCSVITA was determined as the dose required to kill 6 out of 12 rats after 24 h from dosing. To compare the GI and liver toxicities, rats received IPCSVITA or IPC (both 280 mg iron/kg body weight) for 28 days. GI toxicity was assessed macroscopically by scoring lesion severities and microscopically by analyzing the villi/crypt ratio, number of eosinophils/villi and number of Goblet cells/villi. Ferritin was assessed in the small intestine villi and in the liver by immunostaining. Iron deposits in the liver were assessed by Prussian blue staining. Serum iron concentration and transferrin saturation (TSAT) were significantly higher in the IPCSVITA group vs. the IPC and the control groups. Food consumption, body weight, and bowel movement at Day 29 were significantly lower within the IPCSVITA group vs. the IPC or the control groups. The lesion scores in the stomach and in the lower GI tract of the IPCSVITA group were significantly higher than those of the IPC and control groups. The villi/crypt ratio and the number of Goblet cells/villi in the small intestine were significantly lower in IPCSVITA-treated animals than in IPC-treated or control animals. The number of eosinophils per villi was

  6. Preliminary analysis of thermal-infrared multispectral scanner data of the Iron Hill, Colorado carbonatite-alkalic rock complex

    Science.gov (United States)

    Rowan, Lawrence C.; Watson, Kenneth; Miller, Susanne H.

    1992-01-01

    The Iron Hill carbonatite-alkalic igneous rock complex is in the Powderhorn mining district, approximately 40 km south-southwest of Gunnison, Colorado. The complex, which occupies about 30 sq km, was emplaced in metasedimentay and metavolcanic rocks during the later Precambrian or early Cambrian. The main rock types in the complex, from oldest to youngest, are fenite, pyroxenite, uncompahgrite, ijolite, nepheline syenite, and dolomitic carbonatite. The carbonatite is limonitic and forms an elliptially shaped 4 sq km stock. Calcitic and dolomitic carbonatite dikes are also numerous throughout the complex and in the pre-existing rocks. Pyroxenite is the most widespread rock type within the complex, but pyroxene is extensively altered to biotite, phlogopite, and vermiculite. Fenite, which formed through Na, K-metasomatism of the country rocks, typically contains more feldspar and less quartz than the equivalent unaltered country rocks. The other alkalic rock types are less widespread and less well exposed. Parts of the complex are covered by Oligocene ash-flow tuff and alluvial, colluvial, and glacial deposits. Sagebrush and grass cover is moderately dense to very dense at low to intermediate elevations; coniferous tree cover is dense at high elevations and on some north-facing slopes at lower elevations. A new algorithm was used to compute spectral emissivity ratios, independent of any emissivity assumptions. This algorithm has the advantage that any of the possible emissivity ratios can be computed and, thus, a large variety of composite ratio images can be constructed, which permits examination of various geologic hypotheses based on the spectral properties of the surface materials.

  7. Mineralogy and geochemistry of banded iron formation and iron ...

    Indian Academy of Sciences (India)

    The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling–. Langalata iron ore deposits, Singhbhum–North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the geochemical evaluation of different iron ores. The geochemical and ...

  8. Mineralogy and geochemistry of banded iron formation and iron ...

    Indian Academy of Sciences (India)

    The geological complexities of banded iron formation (BIF) and associated iron ores of Jilling–Langalata iron ore deposits, Singhbhum–North Orissa Craton, belonging to Iron Ore Group (IOG) eastern India have been studied in detail along with the geochemical evaluation of different iron ores. The geochemical and ...

  9. Architecture of the Yeast Mitochondrial Iron-Sulfur Cluster Assembly Machinery: THE SUB-COMPLEX FORMED BY THE IRON DONOR, Yfh1 PROTEIN, AND THE SCAFFOLD, Isu1 PROTEIN*

    OpenAIRE

    Ranatunga, Wasantha; Gakh, Oleksandr; Galeano, Belinda K.; Smith, Douglas Y.; Söderberg, Christopher A. G.; Al-Karadaghi, Salam; Thompson, James R.; Isaya, Grazia

    2016-01-01

    The biosynthesis of Fe-S clusters is a vital process involving the delivery of elemental iron and sulfur to scaffold proteins via molecular interactions that are still poorly defined. We reconstituted a stable, functional complex consisting of the iron donor, Yfh1 (yeast frataxin homologue 1), and the Fe-S cluster scaffold, Isu1, with 1:1 stoichiometry, [Yfh1]24·[Isu1]24. Using negative staining transmission EM and single particle analysis, we obtained a three-dimensional reconstruction of th...

  10. 57Fe and 119Sn Moessbauer studies on tetracarbonyl(organoelement IVa-phosphine)iron(O) complexes

    International Nuclear Information System (INIS)

    Ensling, J.; Guetlich, P.; Roesch, L.

    1975-01-01

    57 Fe and 119 Sn Moessbauer effect measurements were performed on a series of complexes of the type (CO) 4 FeL with L being organoelement (IVa)-phosphine, [(CH 3 ) 3 C]sub(3-n)P[E(CH 3 ) 3 ]sub(n) (n = 0,1,2,2; E = Si, Sn), to gain some insight into the nature of the phosphorus-element (IVa) bond as well as the iron-nearest neighbour bond. The results of the Moessbauer measurements are in contradiction to the widely discussed presence of (p → d)sub(π) interaction in the phosphorus-element (IVa) bond. In accordance with NMR and vibrational spectroscopic studies they rather suggest that (p → d)sub(π) interaction be of little importance. (orig.) [de

  11. Immunological effects of iron oxide nanoparticles and iron-based complex drug formulations: Therapeutic benefits, toxicity, mechanistic insights, and translational considerations.

    Science.gov (United States)

    Shah, Ankit; Dobrovolskaia, Marina A

    2018-04-01

    Nanotechnology offers several advantages for drug delivery. However, there is the need for addressing potential safety concerns regarding the adverse health effects of these unique materials. Some such effects may occur due to undesirable interactions between nanoparticles and the immune system, and they may include hypersensitivity reactions, immunosuppression, and immunostimulation. While strategies, models, and approaches for studying the immunological safety of various engineered nanoparticles, including metal oxides, have been covered in the current literature, little attention has been given to the interactions between iron oxide-based nanomaterials and various components of the immune system. Here we provide a comprehensive review of studies investigating the effects of iron oxides and iron-based nanoparticles on various types of immune cells, highlight current gaps in the understanding of the structure-activity relationships of these materials, and propose a framework for capturing their immunotoxicity to streamline comparative studies between various types of iron-based formulations. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. A computational study of dimers and trimers of nitrosyl hydride: Blue shift of NH bonds that are involved in H-bond and orthogonal interactions

    International Nuclear Information System (INIS)

    Solimannejad, Mohammad; Massahi, Shokofeh; Alkorta, Ibon

    2009-01-01

    Ab initio calculations at MP2/aug-cc-pVTZ level were used to analyze the interactions between nitrosyl hydride (HNO) dimers and trimers. The structures obtained have been analyzed with the Atoms in Molecules (AIMs) and Natural Bond Orbital (NBO) methodologies. Four minima were located on the potential energy surface of the dimers. Nine different structures have been obtained for the trimers. Three types of interactions are observed, NH···N and NH···O hydrogen bonds and orthogonal interaction between the lone pair of the oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of dimers and trimers including BSSE and ZPE are in the range 4-8 kJ mol -1 and 12-19 kJ mol -1 , respectively. Blue shift of NH bond upon complex formation in the ranges between 30-80 and 14,114 cm -1 is predicted for dimers and trimers, respectively.

  13. Iron(III) diethylenetriaminepentaacetic acid complex on polyallylamine functionalized multiwalled carbon nanotubes: immobilization, direct electrochemistry and electrocatalysis.

    Science.gov (United States)

    Liu, Hailing; Cui, Yanyun; Li, Pan; Zhou, Yiming; Zhu, Xiaoshu; Tang, Yawen; Chen, Yu; Lu, Tianhong

    2013-05-07

    A nonenzymatic iron(III) diethylenetriaminepentaacetic acid (Fe(III)-DETPA) complex based amperometric sensor for the analytical determination of hydrogen peroxide was developed. By combining the electrostatic interaction between the Fe(III)-DETPA complex and polyallylamine (PAH) functionalized multiwalled carbon nanotubes (MWCNTs) as well as the ionotropic crosslinking interaction between PAH and ethylenediamine-tetramethylene phosphonic acid (EDTMP), the electroactive Fe(III)-DETPA complex was successfully incorporated within the MWCNT matrix, and firmly immobilized on the Au substrate electrode. The fabricated electrochemical sensor was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical methods. The influences of solution pH and ionic strength on the electrochemical sensor were investigated. The prepared electrochemical sensor had a fast response to hydrogen peroxide (<3 s) and an excellent linear range of concentration from 1.25 × 10(-8) to 4.75 × 10(-3) M with a detection limit of 6.3 × 10(-9) M under the optimum conditions.

  14. A comparative study of the spectral, fluorometric properties and photostability of natural curcumin, iron- and boron- complexed curcumin

    Science.gov (United States)

    Mohammed, Fatima; Rashid-Doubell, Fiza; Cassidy, Seamas; Henari, Fryad

    2017-08-01

    Curcumin is a yellow phenolic compound with a wide range of reported biological effects. However, two main obstacles hinder the use of curcumin therapeutically, namely its poor bioavailability and photostability. We have synthesized two curcumin complexes, the first a boron curcumin complex (B-Cur2) and the second an iron (Fe-Cur3) complex of curcumin. Both derivatives showed high fluorescence efficiency (quantum yield) and greater photostability in solution. The improved photostability could be attributed to the coordination structures and the removal of β-diketone group from curcumin. The fluorescence and ultra violet/visible absorption spectra of curcumin, B-Cur2 and Fe-Cur3 all have a similar spectral pattern when dissolved in the same organic solvent. However, a shift towards a lower wavelength was observed when moving from polar to non-polar solvents, possibly due to differences in solvent polarity. A plot of Stokes' shift vs the orientation polarity parameter (Δf) or vs the solvent polarity parameter (ET 30) showed an improved correlation between the solvent polarity parameter than with the orientation polarity parameter and indicating that the red shift observed could be due to hydrogen-bonding between the solvent molecules. A similar association was obtained when Stokes' shift was replaced by maximum synchronous fluorescence. Both B-Cur2 and Fe-Cur3 had larger quantum yields than curcumin, suggesting they may be good candidates for medical imaging and in vitro studies.

  15. Ruthenium and iron complexes with benzotriazole and benzimidazole derivatives as simple models for proton-coupled electron transfer systems

    Directory of Open Access Journals (Sweden)

    Rocha Reginaldo C.

    2001-01-01

    Full Text Available Iron and ruthenium complexes of the type [M-LH]n (where M = RuII,III(NH35(2+,3+, RuII,III(edta2-,- [edta = ethylenedinitrilotetraacetate], or FeII,III(CN5(3-,2- and LH = benzotriazole or benzimidazole were prepared and characterized in aqueous solutions by means of electrochemical and spectroelectrochemical methods. Special emphasis was given to the pH-dependent redox processes, exhibited by all the investigated complexes. From their related Pourbaix diagrams, which displayed a typically Nernstian behavior, the pKa and formal reduction potential values were extracted. In addition, these E1/2 versus pH curves were also used to illustrate the partitioning relationship concerning the redox and acid-base species, and their interconversion equilibria. The active area in which the dependence of the M III/M II couple on the pH takes place, as delimited by pKaIII and pKaII, was taken into account in order to evaluate the usefulness of such simple complexes as models for proton-coupled electron transfer (PCET. The results were interpreted in terms of the acceptor/donor electronic character of the ligands and sigma,pi-metal-ligand interactions in both redox states of the metal ion.

  16. Feasibility of diffuse reflectance infrared Fourier spectroscopy (DRIFTS) to quantify iron-cyanide (Fe-CN) complexes in soil

    Science.gov (United States)

    Sut-Lohmann, Magdalena; Raab, Thomas

    2017-04-01

    Contaminated sites create a significant risk to human health, by poisoning drinking water, soil, air and as a consequence food. Continuous release of persistent iron-cyanide (Fe-CN) complexes from various industrial sources poses a high hazard to the environment and indicates the necessity to analyze considerable amount of samples. At the present time quantitative determination of Fe-CN concentration in soil usually requires a time consuming two step process: digestion of the sample (e.g., micro distillation system) and its analytical detection performed, e.g., by automated spectrophotometrical flow injection analysis (FIA). In order to determine the feasibility of diffuse reflectance infrared Fourier spectroscopy (DRIFTS) to quantify the Fe-CN complexes in soil matrix, 42 soil samples were collected (8 to 12.520 mg kg-1CN) indicating single symmetrical CN band in the range 2092 - 2084 cm-1. Partial least squares (PLS) calibration-validation model revealed IR response to CNtot exceeding 1268 mg kg-1 (limit of detection, LOD). Subsequently, leave-one-out cross-validation (LOO-CV) was performed on soil samples containing low CNtot (900 mg kg-1 resulted in LOD equal to 3494 mg kg-1. Our results indicate that spectroscopic data in combination with PLS statistics can efficiently be used to predict Fe-CN concentrations in soil. We conclude that the protocol applied in this study can strongly reduce the time and costs essential for the spatial and vertical screening of the site affected by complexed Fe-CN.

  17. l-Tyrosine Contained in Dietary Supplement by Chemiluminescence Reaction of an Iron-Phthalocyanine Complex

    Directory of Open Access Journals (Sweden)

    Takao Ohtomo

    2012-01-01

    Full Text Available The chemiluminescence (CL signal immediately appeared when a hydrogen peroxide solution was injected into an iron-phthalocyanine tetrasulfonic acid (Fe-PTS aqueous solution. Moreover, the CL intensity of Fe-PTS decreased by adding L-tyrosine. Based on these results, the determination of trace amounts of L-tyrosine was developed using the quenching-chemiluminescence. The calibration curve of L-tyrosine was obtained in the concentration range of 2.0×10−7 M to 2.0×10−5 M. Moreover, the relative standard deviation (RSD was 1.63 % (=5 for 2.0×10−6 M L-tyrosine, and its detection limits (3σ were 1.81×10−7 M. The spike and recovery experiments for L-tyrosine were performed using a soft drink. Furthermore, the determination of L-tyrosine was applied to supplements containing various kinds of amino acids. Each satisfactory relative recovery was obtained at 98 to 102%.

  18. Solvent-Induced Polymorphism of Iron(II Spin Crossover Complexes

    Directory of Open Access Journals (Sweden)

    Ivan Šalitroš

    2016-07-01

    Full Text Available Two new mononuclear iron(II compounds (1 and (2 of the general formula [Fe(L2](BF42·nCH3CN (L = 4-(2-bromoethyn-1-yl-2,6-bis(pyrazol-1-ylpyridine, n = 1 for (1 and n = 2 for compound (2, were synthesized. The room temperature crystallization afforded concomitant formation of two different solvent analogues: compound (1 exhibiting triclinic P-1 and compound (2 monoclinic C2/c symmetry. Single-crystal X-ray studies confirmed the presence of the LS (low-spin state for both compounds at 180 K and of the HS (high-spin state for compound (2 at 293 K, in full agreement with the magnetic investigations for both solvent polymorphs. Compound (1 exhibits spin transition above 293 K followed by subsequent solvent liberation, while the spin transition of (2 takes already place at 237 K. After complete solvent removal from the crystal lattice, compound (1d (the desolvated polymorph derived from (1 exhibits spin transition centered at 342 K accompanied by a thermal hysteresis loop, while the analogous compound (2d (the desolvated derivate of compound (2 remains blocked in the HS state over all the investigated temperature range.

  19. Electrochemical study of the increased antioxidant capacity of flavonoids through complexation with iron(II) ions

    International Nuclear Information System (INIS)

    Porfírio, Demóstenes Amorim; Ferreira, Rafael de Queiroz; Malagutti, Andréa Renata; Valle, Eliana Maíra Agostini

    2014-01-01

    Highlights: • Metal-Flavonoid complexes exhibit greater antioxidant capacity than the free flavonoid;. • Voltammetric profile is an additional information for determining antioxidant capacity;. • Pyrogallol group is a stronger complex-forming group than the catechol;. • Morin, quercetin and fisetin increased their antioxidant capacity in 15%, 32% and 28%, respectively. - Abstract: Flavonoids are polyphenolic compounds that act as natural antioxidants in the human body through various mechanisms, with an emphasis on suppressing reactive oxygen species (ROS) formation by inhibiting enzymes, the direct capture of ROS, and the regulation/protection of antioxidant defenses. Additionally, flavonoids can coordinate with transition metals to catalyze electron transport and promote free radical capture. Recently, metal ion chelation mechanisms have generated considerable interest, as experimental data show that flavonoids in metal complexes exhibit greater antioxidant activity than free flavonoids. However, few studies have correlated the complexing properties of flavonoids with their antioxidant capacity. Thus, the aim of this study was to use the CRAC (Ceric Reducing Antioxidant Capacity) electrochemical assay to measure the antioxidant capacity of five free flavonoids and Fe 2+ -flavonoid complexes. In addition, the interactions between the flavonoids and Fe 2+ were analyzed based on the oxidation peaks formed in their cyclic voltammograms

  20. Nickel and iron complexes with N,P,N-type ligands: synthesis, structure and catalytic oligomerization of ethylene.

    Science.gov (United States)

    Kermagoret, Anthony; Tomicki, Falk; Braunstein, Pierre

    2008-06-14

    The N,P,N-type ligands bis(2-picolyl)phenylphosphine (), bis(4,5-dihydro-2-oxazolylmethyl)phenylphosphine (), bis(4,4-dimethyl-2-oxazolylmethyl)phenylphosphine () and bis(2-picolyloxy)phenylphosphine () were used to synthesize the corresponding pentacoordinated Ni(ii) complexes [Ni{bis(2-picolyl)phenylphosphine}Cl(2)] (), [Ni{bis(4,5-dihydro-2-oxazolylmethyl)phenylphosphine}Cl(2)] (), [Ni{bis(4,4-dimethyl-2-oxazolylmethyl)phenylphosphine}Cl(2)] () and [Ni{bis(2-picolyloxy)phenylphosphine}Cl(2)] (), respectively. The hexacoordinated iron complexes [Fe{bis(2-picolyl)phenylphosphine}(2)][Cl(3)FeOFeCl(3)] (), [Fe{bis(4,5-dihydro-2-oxazolylmethyl)phenylphosphine}(2)][Cl(3)FeOFeCl(3)] () and the tetracoordinated complex [Fe{bis(4,4-dimethyl-2-oxazolylmethyl)phenylphosphine}Cl(2)] (abbreviated [FeCl(2)(NPN(Me2)-N,N)]) were prepared by reaction of FeCl(2).4H(2)O with ligands , respectively. The crystal structures of the octahedral complexes and , determined by X-ray diffraction, showed that two tridentate ligands are facially coordinated to the metal centre with a cis-arrangement of the P atoms and the dianion (mu-oxo)bis[trichloroferrate(iii)] compensates the doubly positive charge of the complex. The cyclic voltammograms of and showed two reversible redox couples attributed to the reduction of the dianion (Fe(2)OCl(6))(2-) (-0.24 V for and -0.20 V for vs. SCE) and to the oxidation of the Fe(ii) ion of the complex (0.67 V for and 0.52 V for vs. SCE). The cyclic voltammogram of [FeCl(2)(NPN(Me2)-N,N)] showed a reversible redox couple at -0.17 V vs. SCE assigned to the oxidation of the Fe(ii) atom and an irreversible process at 0.65 V. The complexes , and [FeCl(2)(NPN(Me2)-N,N)] have been evaluated in the catalytic oligomerization of ethylene with AlEtCl(2) or MAO as cocatalyst. The nickel complex proved to be the most active precatalyst in the series, with a turnover frequency (TOF) of 61 800 mol(C(2)H(4)) mol(Ni)(-1) h(-1) with 10 equiv. of AlEtCl(2) and 12 200 mol(C(2)H

  1. Fighting Fenton Chemistry: A Highly Active Iron(III) Tetracarbene Complex in Epoxidation Catalysis.

    Science.gov (United States)

    Kück, Jens W; Anneser, Markus R; Hofmann, Benjamin; Pöthig, Alexander; Cokoja, Mirza; Kühn, Fritz E

    2015-12-07

    Organometallic Fe complexes with exceptionally high activities in homogeneous epoxidation catalysis are reported. The compounds display Fe(II) and Fe(III) oxidation states and bear a tetracarbene ligand. The more active catalyst exhibits activities up to 183 000 turnovers per hour at room temperature and turnover numbers of up to 4300 at -30 °C. For the Fe(III) complex, a decreased Fenton-type reactivity is observed compared with Fe(II) catalysts reported previously as indicated by a substantially lower H2 O2 decomposition and higher (initial) turnover frequencies. The dependence of the catalyst performance on the catalyst loading, substrate, water addition, and the oxidant is investigated. Under all applied conditions, the advantageous nature of the use of the Fe(III) complex is evident. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A giant chlorophyll-protein complex induced by iron deficiency in cyanobacteria

    NARCIS (Netherlands)

    Boekema, E.J.; Hifney, A.; Yakushevska, A.E.; Piotrowski, M.; Keegstra, W.; Berry, S.; Michel, K.-P.; Pistorius, E.K.; Kruip, J.

    2001-01-01

    Cyanobacteria are abundant throughout most of the world's water bodies and contribute significantly to global primary productivity through oxygenic photosynthesis. This reaction is catalysed by two membrane-bound protein complexes, photosystem I (PSI) and photosystem II (PSII), which both contain

  3. Fischer aminocarbene complexes of chromium and iron: Anomalous electrochemical reduction of p-carbonyl substituted derivatives

    Czech Academy of Sciences Publication Activity Database

    Hoskovcová, I.; Zvěřinová, R.; Roháčová, J.; Dvořák, D.; Tobrman, T.; Záliš, Stanislav; Ludvík, Jiří

    2011-01-01

    Roč. 56, č. 19 (2011), s. 6853-6859 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400813 Institutional research plan: CEZ:AV0Z40400503 Keywords : DFT calculations * electrochemistry * Fischer aminocarbene complexes Subject RIV: CG - Electrochemistry Impact factor: 3.832, year: 2011

  4. Boosting Vis/NIR Charge-Transfer Absorptions of Iron(II) Complexes by N-Alkylation and N-Deprotonation in the Ligand Backbone.

    Science.gov (United States)

    Mengel, Andreas K C; Bissinger, Christian; Dorn, Matthias; Back, Oliver; Förster, Christoph; Heinze, Katja

    2017-06-12

    Reversing the metal-to-ligand charge transfer ( 3 MLCT)/metal-centered ( 3 MC) excited state order in iron(II) complexes is a challenging objective, yet would finally result in long-sought luminescent transition-metal complexes with an earth-abundant central ion. One approach to achieve this goal is based on low-energy charge-transfer absorptions in combination with a strong ligand field. Coordinating electron-rich and electron-poor tridentate oligopyridine ligands with large bite angles at iron(II) enables both low-energy MLCT absorption bands around 590 nm and a strong ligand field. Variations of the electron-rich ligand by introducing longer alkyl substituents destabilizes the iron(II) complex towards ligand substitution reactions while hardly affecting the optical properties. On the other hand, N-deprotonation of the ligand backbone is feasible and reversible, yielding deep-green complexes with charge-transfer bands extending into the near-IR region. Time-dependent density functional theory calculations assign these absorption bands to transitions with dipole-allowed ligand-to-ligand charge transfer character. This unique geometric and electronic situation establishes a further regulating screw to increase the energy gap between potentially emitting charge-transfer states and the non-radiative ligand field states of iron(II) dyes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Quantitative comparison of the effect of methyl D- glycopyranosides as cosolutes on the rates of base hydrolysis and aquation of some iron(II)-diimine complexes

    NARCIS (Netherlands)

    Milde, Siobhan P.; Blandamer, Michael J.; Burgess, John; Engberts, Jan B.F.N.; Galema, Saskia A.; Hubbard, Colin D.

    1999-01-01

    The kinetics of base hydrolysis and of aquation of some iron(II)–diimine complexes in the presence of stereoisomeric carbohydrates were monitored spectrophotometrically at 25.0°C. In basic aqueous solution dissociation of both Fe(1,10-phenanthroline)32+ and Fe(2,2\\'-bipyridine)32+ is accelerated

  6. Iron and zinc complexation in wild-type and ferritin-expressing wheat grain: implications for mineral transport into developing grain

    DEFF Research Database (Denmark)

    Neal, Andrew L; Geraki, Kalotina; Borg, Søren

    2013-01-01

    We have used synchrotron-based X-ray fluorescence and absorption techniques to establish both metal distribution and complexation in mature wheat grains. In planta, extended X-ray absorption fine structure (EXAFS) spectroscopy reveals iron phytate and zinc phytate structures in aleurone cells and...

  7. Bioinspired Design and Computational Prediction of Iron Complexes with Pendant Amines for the Production of Methanol from CO2 and H2.

    Science.gov (United States)

    Chen, Xiangyang; Yang, Xinzheng

    2016-03-17

    Inspired by the active site structure of [FeFe]-hydrogenase, we built a series of iron dicarbonyl diphosphine complexes with pendant amines and predicted their potentials to catalyze the hydrogenation of CO2 to methanol using density functional theory. Among the proposed iron complexes, [(P(tBu)2N(tBu)2H)FeH(CO)2(COOH)](+) (5COOH) is the most active one with a total free energy barrier of 23.7 kcal/mol. Such a low barrier indicates that 5COOH is a very promising low-cost catalyst for high-efficiency conversion of CO2 and H2 to methanol under mild conditions. For comparison, we also examined Bullock's Cp iron diphosphine complex with pendant amines, [(P(tBu)2N(tBu)2H)FeHCp(C5F4N)](+) (5Cp-C5F4N), as a catalyst for hydrogenation of CO2 to methanol and obtained a total free energy barrier of 27.6 kcal/mol, which indicates that 5Cp-C5F4N could also catalyze the conversion of CO2 and H2 to methanol but has a much lower efficiency than our newly designed iron complexes.

  8. Electrochemical Polymerization of Iron(III) Polypyridyl Complexes through C-C Coupling of Redox Non-innocent Phenolato Ligands.

    Science.gov (United States)

    Unjaroen, Duenpen; Swart, Marcel; Browne, Wesley R

    2017-01-03

    Phenolato moieties impart redox flexibility to metal complexes due their accessible (oxidative) redox chemistry and have been proposed as functional ligand moieties in redox non-innocent ligand based transition metal catalysis. Here, the electro- and spectroelectrochemistry of phenolato based μ-oxo-diiron(III) complexes [(L 1 )Fe(μ-O)Fe(L 1 )] 2+ (1) and [(L 2 )Fe(μ-O)Fe(L 2 )] 2+ (2), where L 1 = 2-(((di(pyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino)methyl)phenol and L 2 = 3,5-di-tert-butyl-2-(((di(pyridin-2-yl)methyl)(pyridin-2-ylmethyl)amino)methyl)phenol, is described. The electrochemical oxidation of 1 in dichloromethane results in aryl C-C coupling of phenoxyl radical ligand moieties to form tetra nuclear complexes, which undergo subsequent oxidation to form iron(III) phenolato based polymers (poly-1). The coupling is blocked by placing tert-butyl groups at para and ortho positions of phenol units (i.e., 2). Poly-1 shows two fully reversible redox processes in monomer free solution. Assignment of species observed during the electrochemical and chemical {(NH 4 ) 2 [Ce IV (NO 3 ) 6 ]} oxidation of 1 in acetonitrile is made by comparison with the UV-vis-NIR absorption and resonance micro-Raman spectroelectrochemistry of poly-1, and by DFT calculations, which confirms that oxidative coupling occurs in acetonitrile also. However, in contrast to that observed in dichloromethane, in acetonitrile, the oligomers formed are degraded in terms of a loss of the Fe(III)-O-Fe(III) bridge by protonation. The oxidative redox behavior of 1 and 2 is, therefore, dominated by the formation and reactivity of Fe(III) bound phenoxyl radicals, which considerably holds implications in regard to the design of phenolato based complexes for oxidation catalysis.

  9. Spectrophotometric Determination of Iron(II after Solid Phase Extraction of Its 2,2′ Bipyridine Complex on Silica Gel-Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    Nahid Pourreza

    2013-01-01

    Full Text Available A new solid phase extraction procedure was developed for preconcentration of iron(II using silica gel-polyethylene glycol (silica-PEG as an adsorbent. The method is based on retention of iron(II as 2,2′ bipyridine complex on silica-PEG. The retained complex is eluted by 1.0 mol L−1 of sulfuric acid-acetone mixture (1:2 and its absorbance is measured at 518 nm, spectrophotometrically. The effects of different parameters such as pH, concentration of the reagent, eluting reagent, sample volume, amount of adsorbent, and interfering ions were investigated. The calibration graph was linear in the range of 1–60 ng mL−1 of iron(II. The limit of detection based on 3Sb was 0.57 ng mL−1 and relative standard deviations (R.S.D for ten replicate measurements of 12 and 42 ng mL−1 of iron(II were 2.4 and 1.7%, respectively. The method was applied to the determination of of iron(II in water, multivitamin tablet, and spinach samples.

  10. Iron complexation to histone deacetylase inhibitors SAHA and LAQ824 in PEGylated liposomes can considerably improve pharmacokinetics in rats.

    Science.gov (United States)

    Wang, Yan; Tu, Sheng; Steffen, Dana; Xiong, May

    2014-01-01

    The formulation of histone deacetylase inhibitors (HDACi) is challenging due to poor water solubility and rapid elimination of drugs in vivo. This study investigated the effects of complexing iron (Fe3+) to the HDACi suberoylanilide hydroxamic acid (SAHA) and LAQ824 (LAQ) prior to their encapsulation into PEGylated liposomes, and investigated whether this technique could improve drug solubility, in vitro release and in vivo pharmacokinetic (PK) properties. METHODS. The reaction stoichiometry, binding constants and solubility were measured for Fe complexes of SAHA and LAQ. The complexes were passively encapsulated into PEGylated liposomes and characterized by size distribution, zeta-potential, encapsulation efficiency (EE), and in vitro drug release studies. PC-3 cells were used to verify the in vitro anticancer activity of the formulations. In vivo pharmacokinetic properties of liposomal LAQ-Fe (L-LAQ-Fe) was evaluated in rats. RESULTS. SAHA and LAQ form complexes with Fe at 1:1 stoichiometric ratio, with a binding constant on the order of 104 M-1. Fe complexation improved the aqueous solubility and the liposomal encapsulation efficiency of SAHA and LAQ (29-35% EE, final drug concentration > 1 mM). Liposomal encapsulated complexes (L-HDACi-Fe) exhibited sustained in vitro release properties compared to L-HDACi but cytotoxicity on PC-3 cells was comparable to free drugs. The PK of L-LAQ-Fe revealed 15-fold improvement in the plasma t1/2 (12.11 h)and 211-fold improvement in the AUC∞ (105.7 µg·h/ml) compared to free LAQ (0.79 h, 0.5 µg·h/ml). Similarly, the plasma t1/2 of Fe was determined to be 11.83 h in a separate experiment using radioactive Fe-59. The majority of Fe-59 activity was found in liver and spleen of rats and correlates with liposomal uptake by the mononuclear phagocyte system. CONCLUSIONS. We have demonstrated that encapsulation of Fe complexes of HDACi into PEGylated liposomes can improve overall drug aqueous solubility, in vitro release and in

  11. Rieske iron-sulfur protein of the cytochrome bc(1) complex: a potential target for fungicide discovery.

    Science.gov (United States)

    Yang, Wen-Chao; Li, Hui; Wang, Fu; Zhu, Xiao-Lei; Yang, Guang-Fu

    2012-07-23

    The cytochrome bc(1) complex (complex III, cyt bc(1)) is an essential component of cellular respiration. Cyt bc(1) has three core subunits that are required for its catalytic activity: cytochrome b, cytochrome c(1), and the Rieske iron-sulfur protein (ISP). Although most fungicides inhibit this enzyme by binding to the cytochrome b subunit, resistance to these fungicides has developed rapidly due to their widespread application. Resistance is mainly associated with mutations in cytochrome b, the only subunit encoded by mitochondrial DNA. Recently, the flexibility and motion of the ISP and its essential role in electron transfer have received intense attention; this leads us to propose a new classification of cyt bc(1) inhibitors (three types of Q(o) inhibitors) that mobilize, restrict, or fix the rotation of the ISP. Importantly, the strengths of the ISP-inhibitor interactions correlate with inhibitor activity and the development of resistance to Q(o) inhibitors, thereby offering clues for designing novel cyt bc(1) inhibitors with high potency and a low risk of resistance. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. UHV deposition and characterization of a mononuclear iron(III β-diketonate complex on Au(111

    Directory of Open Access Journals (Sweden)

    Irene Cimatti

    2014-11-01

    Full Text Available The adsorption of the sterically hindered β-diketonate complex Fe(dpm3, where Hdpm = dipivaloylmethane, on Au(111 was investigated by ultraviolet photoelectron spectroscopy (UPS and scanning tunnelling microscopy (STM. The high volatility of the molecule limited the growth of the film to a few monolayers. While UPS evidenced the presence of the β-diketonate ligands on the surface, the integrity of the molecule on the surface could not be assessed. The low temperature STM images were more informative and at submonolayer coverage they showed the presence of regular domains characterized by a flat morphology and height of ≈0.3 nm. Along with these domains, tetra-lobed features adsorbed on the kinks of the herringbone were also observed. DFT-simulated images of the pristine molecule and its possible decomposition products allowed to assess the partial fragmentation of Fe(dpm3 upon adsorption on the Au(111 surface. Structural features with intact molecules were only observed for the saturation coverage. An ex situ prepared thick film of the complex was also investigated by X-ray magnetic circular dichroism (XMCD and features typical of high-spin iron(III in octahedral environment were observed.

  13. An iron(II) diketonate–diamine complex as precursor for thin film fabrication by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bratvold, Jon E., E-mail: j.e.bratvold@kjemi.uio.no [Centre for Materials Science and Nanotechnology (SMN)/Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo (Norway); Carraro, Giorgio [Department of Chemistry, University of Padova and INSTM, via F. Marzolo 1, I-35131 Padova (Italy); Barreca, Davide [CNR-IENI and INSTM, Department of Chemistry, University of Padova, via F. Marzolo 1, I-35131 Padova (Italy); Nilsen, Ola [Centre for Materials Science and Nanotechnology (SMN)/Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo (Norway)

    2015-08-30

    Highlights: • First report of Fe(hfa){sub 2}TMEDA as precursor in ALD and MLD. • Hybrid organic–inorganic films with oxalic acid as co-reactant between 125 and 350 °C. • Surface saturation evidenced by quartz crystal microbalance (QCM) analysis. • XPS confirms complete preservation of Fe(II) from precursor to film. • Deposition of α-Fe{sub 2}O{sub 3} when using ozone as co-reactant. - Abstract: A new divalent Fe precursor has been explored for deposition of iron-containing thin films by atomic layer deposition and molecular layer deposition (ALD/MLD). The Fe(II) β-diketonate-diamine complex, Fe(hfa){sub 2}TMEDA, (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, TMEDA = N,N,N′,N′-tetramethylethylenediamine) can be handled in air, and sublimation at 60 °C ensures a satisfactory vaporization rate. The reactivity of the precursor does not allow for direct reaction with water as co-reactant. Nevertheless, it reacts with carboxylic acids, resulting in organic–inorganic hybrid materials, and with ozone, yielding α-Fe{sub 2}O{sub 3}. The divalent oxidation state of iron was maintained during deposition when oxalic acid was used as co-reactant, demonstrating the first preservation of Fe(II) from precursor to film during an MLD process. A self-saturating growth mode was proven by in situ quartz crystal microbalance (QCM) measurements, and the films were further characterized by grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS)

  14. Importance of iron complexation for Fenton-mediated hydroxyl radical production at circumneutral pH

    Directory of Open Access Journals (Sweden)

    Christopher J. Miller

    2016-08-01

    Full Text Available The reaction between Fe(II and H2O2 to yield hydroxyl radicals (HO•, the Fenton reaction, is of interest due to its role in trace metal and natural organic matter biogeochemistry, its utility in water treatment and its role in oxidative cell degradation and associated human disease. There is significant dispute over whether HO•, the most reactive of the so-called reactive oxygen species, is formed in this reaction, particularly under circumneutral conditions relevant to natural systems. In this work we have studied the oxidation kinetics of Fe(II complexed by L = citrate, ethylenediaminetetraacetic acid (EDTA and diethylenetriaminepentaacetic acid (DTPA and also measured HO• production using phthalhydrazide as a probe compound at pH 8.2. It is shown that HO• is the sole product of the Fe(IIL-H2O2 reaction for L = EDTA and DTPA, with kinetic modelling of the full reaction pathway utilized to confirm this finding. Quantitative HO• production also appears likely for L = citrate, although uncertainties with the speciation of Fe(II-citrate complexes as well as difficulties in modelling the oxidation kinetics of these complexes has prevented a definitive conclusion. In the absence of ligands at circumneutral pH, inorganic Fe(II reacts with H2O2 to yield a species other than HO•, contrary to the well-established production of HO• from inorganic Fe(II at low pH. Our results suggest that at high pH Fe(II must be complexed for HO• production to occur.

  15. Role of the Bridging Arylethynyl Ligand in Bi- and Trinuclear Ruthenium and Iron Complexes

    Czech Academy of Sciences Publication Activity Database

    Klein, A.; Lavastre, O.; Fiedler, Jan

    2006-01-01

    Roč. 25, č. 3 (2006), s. 635-643 ISSN 0276-7333 R&D Projects: GA MŠk 1P05OC068; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : X-ray crystal * nonlinear optical properties * sigma-acetylide complexes Subject RIV: CG - Electrochemistry Impact factor: 3.632, year: 2006

  16. Thermal behaviour of TEGMMA copolymers obtained by photopolymerization using iron complexes

    OpenAIRE

    Rigoli, I. C.; Schmitt, C. C.; Ramos, L. A.; Neumann, M. G.; Cavalheiro, E. T. G.

    2007-01-01

    Copolymers of methyl methacrylate (MMA) and triethyleneglycol dimethacrylate (TEGDMA) obtained by photoinitiated polymerization using Fe(III) complexes were submitted to thermogravimetry (TGA) under dynamic air atmosphere and N2, and differential scanning calorimetric analysis (DSC). Thermal events were observed only between 90 - 110 ºC. Glass transitions were observed at ca. 100 ºC, followed by an exothermic peak at 170 ºC. The exothermic peak was assigned to a thermal curing process due to ...

  17. Iron-regulatory proteins DmdR1 and DmdR2 of Streptomyces coelicolor form two different DNA-protein complexes with iron boxes.

    OpenAIRE

    Flores, Francisco J; Martín, Juan F

    2004-01-01

    In high G+C Gram-positive bacteria, the control of expression of genes involved in iron metabolism is exerted by a DmdR [divalent (bivalent) metal-dependent regulatory protein] in the presence of Fe2+ or other bivalent ions. The dmdR1 and dmdR2 genes of Streptomyces coelicolor were overexpressed in Escherichia coli and the DmdR1 and DmdR2 proteins were purified to homogeneity. Electrophoretic mobility-shift assays showed that both DmdR1 and DmdR2 bind to the 19-nt tox and desA iron boxes form...

  18. Heteroleptic and Homoleptic Iron(III Spin-Crossover Complexes; Effects of Ligand Substituents and Intermolecular Interactions between Co-Cation/Anion and the Complex

    Directory of Open Access Journals (Sweden)

    Wasinee Phonsri

    2017-08-01

    Full Text Available The structural and magnetic properties of a range of new iron(III bis-tridentate Schiff base complexes are described with emphasis on how intermolecular structural interactions influence spin states and spin crossover (SCO in these d5 materials. Three pairs of complexes were investigated. The first pair are the neutral, heteroleptic complexes [Fe(3-OMe-SalEen(thsa] 1 and [Fe(3-MeOSalEen(3-EtOthsa] 2, where 3-R-HSalEen = (E-2-(((2-(ethylaminoethyliminomethyl-6-R-phenol and 3-R-H2thsa = thiosemicarbazone-3-R-salicylaldimine. They display spin transitions above room temperature. However, 2 shows incomplete and gradual change, while SCO in 1 is complete and more abrupt. Lower cooperativity in 2 is ascribed to the lack of π–π interactions, compared to 1. The second pair, cationic species [Fe(3-EtOSalEen2]NO3 3 and [Fe(3-EtOSalEen2]Cl 4 differ only in the counter-anion. They show partial SCO above room temperature with 3 displaying a sharp transition at 343 K. Weak hydrogen bonds from cation to Cl− probably lead to weaker cooperativity in 4. The last pair, CsH2O[Fe(3-MeO-thsa2] 5 and Cs(H2O2[Fe(5-NO2-thsa2] 6, are anionic homoleptic chelates that have different substituents on the salicylaldiminate rings of thsa2−. The Cs cations bond to O atoms of water and the ligands, in unusual ways thus forming attractive 1D and 3D networks in 5 and 6, respectively, and 5 remains HS (high spin at all temperatures while 6 remains LS (low spin. Comparisons are made to other literature examples of Cs salts of [Fe(5-R-thsa2]− (R = H and Br.

  19. Scientific Opinion on the safety of the complexation product of sodium tartrate and iron(III) chloride as a food additive

    OpenAIRE

    2015-01-01

    The complexation product of sodium tartrates and iron(III) chloride (Fe mTA) is proposed for use as an anti-caking agent, only in salt or its substitutes, with a maximum use level of 106 mg Fe mTA/kg salt. Fe mTA can be expected to dissociate into its constituent iron(III) and tartrate components upon ingestion. Studies in rats demonstrated that up to 90 % of ingested DL-tartrate or tartaric acid were absorbed, studies in humans suggested that only 20 % of an ingested dose of tartaric acid we...

  20. Photoactive Nitric Oxide Delivery Systems based on Metal Nitrosyl-Biomaterial Composites

    Science.gov (United States)

    Heilman, Brandon James

    Gaseous NO has been recognized as a potent antibiotic even against highly drug-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) in both animal and human studies. However, difficulties in the delivery of the toxic (and reactive) gas demands innovative techniques to deliver NO in a controlled manner to malignant sites throughout the body. Metal nitrosyls reported by our group have demonstrated rapid NO release under the complete control of visible and NIR light. Careful incorporation of these photoactive nitrosyls into polymer matrices has afforded a set of nitrosyl-polymer composites in order to localize the NO-donors at a targeted site, ensure reliable NO release kinetics in vivo, and prevent potentially cytotoxic interactions of the metal nitrosyl or its reaction-products with the treatment site. The work presented in this thesis was pursued to derive clinically relevant NO-delivery systems and demonstrate their utility for the treatment of infection. In chapter 2, an NO-releasing polyurethane film (PUX-NO) is described with dispersed xerogel particles containing up to 3 mol% of [Mn(PaPy 3)(NO)](ClO4) entrapped in a silica matrix and swelled with excess moisture. The polyurethane based xerogel-nitrosyl (PUX-NO) films demonstrated rapid NO photorelease upon illumination with low-power visible light which was sufficient to eradicate clinically relevant loads (105 CFU mL-1 ) of several gram-positive and gram-negative pathogenic bacteria, including a strain of methicillin-resistant of S. aureus. The results of this study suggest that PUX-NO films are suitable for use as a NO-releasing occlusive film for the treatment of skin and soft-tissue infections or chronic, non-healing wounds. Since the NO-release rate from the films can be modulated by simple adjustment of the intensity of the light source, the films could be used to first clear the microbial burden from the wound site using high fluxes of NO, and then, provide a moderate

  1. The obtaining of iron acetate from processed iron comprising catalyst of ammonia synthesis

    International Nuclear Information System (INIS)

    Mansurov, M.M.; Lugovenko, A.N.; Mirzoeva, M.M.

    1993-01-01

    Present article is devoted to obtaining of iron acetate from processed iron comprising catalyst of ammonia synthesis. The method of synthesis of iron acetate from processed iron comprising catalyst of ammonia synthesis was elaborated. The structure of complex was determined.

  2. Nitrosyl isomerism in amorphous Mn(TPP)(NO) solids.

    Science.gov (United States)

    Kurtikyan, Tigran S; Hayrapetyan, Vardan A; Martirosyan, Garik G; Ghazaryan, Robert K; Iretskii, Alexei V; Zhao, Hailiang; Pierloot, Kristine; Ford, Peter C

    2012-12-25

    Reaction of NO with amorphous Mn(TPP) layers gives two Mn(TPP)(NO) isomers with linear and bent Mn-N-O geometries that reversibly interconvert with changes in temperature. DFT computations predict that the linear complex is the singlet ground state while the bent structure is a triplet state.

  3. Nuclear inelastic scattering study of a dinuclear iron(II) complex showing a direct spin transition

    Energy Technology Data Exchange (ETDEWEB)

    Wolny, J. A., E-mail: wolny@physik.uni-kl.de [University of Kaiserslautern, Department of Physics (Germany); Garcia, Y. [Université Catholique de Louvain, Institute of Condensed Matter and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST) (Belgium); Faus, I.; Rackwitz, S. [University of Kaiserslautern, Department of Physics (Germany); Schlage, K.; Wille, H.-C. [DESY (Germany); Schünemann, V. [University of Kaiserslautern, Department of Physics (Germany)

    2016-12-15

    The results of the nuclear inelastic scattering (NIS)/nuclear resonance vibrational spectroscopy (NRVS) for the powder spectra of dimeric [Fe {sub 2}L{sub 5}(NCS) {sub 4}] (L = N-salicylidene-4-amino-1,2,4-triazole) complex are presented. This system is spin crossover (SCO) material tagged with a fluorophore that can sense or “feel” the SCO signal ripping through the molecular network and thereby providing an opportunity to register the SCO transition. The spectra have been measured for the low-spin and high-spin phases of the complex. The high-spin isomer reveals one broad band above 200 cm {sup −1}, while the low-spin one displays two intense bands in the range from 390 to 430 cm {sup −1}, accompanied by a number of weaker bands below this area and one at ca. 490 cm {sup −1}. A normal coordinate analysis based on density functional calculations yields the assignment of the spin marker bands to particular molecular modes. In addition the vibrational contribution to the spin transition has been estimated.

  4. Expanding the Therapeutic Potential of the Iron Chelator Deferasirox in the Development of Aqueous Stable Ti(IV) Anticancer Complexes.

    Science.gov (United States)

    Loza-Rosas, Sergio A; Vázquez-Salgado, Alexandra M; Rivero, Kennett I; Negrón, Lenny J; Delgado, Yamixa; Benjamín-Rivera, Josué A; Vázquez-Maldonado, Angel L; Parks, Timothy B; Munet-Colón, Charlene; Tinoco, Arthur D

    2017-07-17

    The recent X-ray structure of titanium(IV)-bound human serum transferrin (STf) exhibiting citrate as a synergistic anion reveals a difference in Ti(IV) coordination versus iron(III), the metal endogenously delivered by the protein to cells. This finding enriches our bioinspired drug design strategy for Ti(IV)-based anticancer therapeutics, which applies a family of Fe(III) chelators termed chemical transferrin mimetic (cTfm) ligands to inhibit Fe bioavailability in cancer cells. Deferasirox, a drug used for iron overload disease, is a cTfm ligand that models STf coordination to Fe(III), favoring Fe(III) binding versus Ti(IV). This metal affinity preference drives deferasirox to facilitate the release of cytotoxic Ti(IV) intracellularly in exchange for Fe(III). An aqueous speciation study performed by potentiometric titration from pH 4 to 8 with micromolar levels of Ti(IV) deferasirox at a 1:2 ratio reveals exclusively Ti(deferasirox) 2 in solution. The predominant complex at pH 7.4, [Ti(deferasirox) 2 ] 2- , exhibits the one of the highest aqueous stabilities observed for a potent cytotoxic Ti(IV) species, demonstrating little dissociation even after 1 month in cell culture media. UV-vis and 1 H NMR studies show that the stability is unaffected by the presence of biomolecular Ti(IV) binders such as citrate, STf, and albumin, which have been shown to induce dissociation or regulate cellular uptake and can alter the activity of other antiproliferative Ti(IV) complexes. Kinetic studies on [Ti(deferasirox) 2 ] 2- transmetalation with Fe(III) show that a labile Fe(III) source is required to induce this process. The initial step of this process occurs on the time scale of minutes, and equilibrium for the complete transmetalation is reached on a time scale of hours to a day. This work reveals a mechanism to deliver Ti(IV) compounds into cells and trigger Ti(IV) release by a labile Fe(III) species. Cellular studies including other cTfm ligands confirm the Fe(III) depletion

  5. Iron-Targeting Antitumor Activity of Gallium Compounds and Novel Insights Into Triapine®-Metal Complexes

    OpenAIRE

    Chitambar, Christopher R.; Antholine, William E.

    2013-01-01

    Significance: Despite advances made in the treatment of cancer, a significant number of patients succumb to this disease every year. Hence, there is a great need to develop new anticancer agents. Recent Advances: Emerging data show that malignant cells have a greater requirement for iron than normal cells do and that proteins involved in iron import, export, and storage may be altered in cancer cells. Therefore, strategies to perturb these iron-dependent steps in malignant cells hold promise ...

  6. Influence of ocean acidification on the organic complexation of iron and copper in Northwest European shelf seas; a combined observational and model study

    Directory of Open Access Journals (Sweden)

    Lizeth eAvendaño

    2016-04-01

    Full Text Available The pH of aqueous solutions is known to impact the chemical speciation of trace metals. In this study we conducted titrations of coastal seawaters with iron and copper at pH 7.91, 7.37 and 6.99 (expressed on the total pH scale. Changes in the concentration of iron and copper that complexed with the added ligands 1-nitroso-2-napthol and salicylaldoxime respectively were determined by adsorptive cathodic stripping voltammetry - competitive ligand equilibrium (AdCSV-CLE. Interpretation of the results, assuming complexation by a low concentration of discrete ligands, showed that conditional stability constants for iron complexes increased relative to inorganic iron complexation as pH decreased by approximately 1 log unit per pH unit, whilst those for copper did not change. No trend was observed for concentrations of iron and copper complexing ligands over the pH range examined. We also interpreted our titration data by describing chemical binding and polyelectrolytic effects using non-ideal competitive adsorption in Donnan-like gels (NICA-Donnan model in a proof of concept study. The NICA-Donnan approach allows for the development of a set of model parameters that are independent of ionic strength and pH, and thus calculation of metal speciation can be undertaken at ambient sample pH or the pH of a future, more acidic ocean. There is currently a lack of basic NICA-Donnan parameters applicable to marine dissolved organic matter (DOM so we assumed that the measured marine dissolved organic carbon could be characterized as terrestrial fulvic acids. Generic NICA-Donnan parameters were applied within the framework of the software program visual MINTEQ and the metal –added ligand concentrations [MeAL] calculated for the AdCSV-CLE conditions. For copper, calculated [MeAL] using the NICA-Donnan model for DOM were consistent with measured [MeAL], but for iron an inert fraction with kinetically inhibited dissolution was required in addition to the NICA

  7. Organomineral Complexation at the Nanoscale: Iron Speciation and Soil Carbon Stabilization

    Science.gov (United States)

    Coward, E.; Thompson, A.; Plante, A. F.

    2016-12-01

    Much of the uncertainty in the biogeochemical behavior of soil carbon (C) in tropical ecosystems derives from an incomplete understanding of soil C stabilization processes. The 2:1 phyllosilicate clays often associated with temperate organomineral complexation are largely absent in tropical soils due to extensive weathering. In contrast, these soils contain an abundance of Fe- and Al-containing short-range-order (SRO) mineral phases capable of C stabilization through sorption or co-precipitation, largely enabled by high specific surface area (SSA). SRO-mediated organomineral associations may thus prove a critical, yet matrix-selective, driver of the long-term C stabilization capacity observed in tropical soils. Characterizing the interactions between inherently heterogeneous organic matter and amorphous mineralogy presses the limits of current analytical techniques. This work pairs inorganic selective dissolution with high-resolution assessment of Fe speciation to determine the contribution of extracted mineral phases to the mineral matrix, and to C stabilization capacity. Surface (0-20 cm) samples were taken from 20 quantitative soil pits within the Luquillo Critical Zone Observatory in northeast Puerto Rico stratified across granodioritic and volcaniclastic parent materials. 57Fe-Mössbauer spectroscopy (MBS) and x-ray diffraction (XRD) before and after Fe-SOM extraction were used to assess changes in the mineralogical matrix associated with SOM dissolution, while N2-BET sorption was used to determine the contributions of the extractable phases to SSA. Results indicate (1) selective extraction of soil C produces significant shifts in Fe phase distribution, (2) SRO minerals contribute substantially to SSA, and (3) SRO minerals appear protected by more crystalline phases via physical mechanisms, rather than dissolution-dependent chemical bonds. This nanoscale characterization of Fe-C complexes thus provides evidence for both anticipated mineral-organic and

  8. Deficiency of the iron-sulfur clusters of mitochondrial reduced nicotinamide-adenine dinucleotide-ubiquinone oxidoreductase (complex I) in an infant with congenital lactic acidosis.

    Science.gov (United States)

    Moreadith, R W; Batshaw, M L; Ohnishi, T; Kerr, D; Knox, B; Jackson, D; Hruban, R; Olson, J; Reynafarje, B; Lehninger, A L

    1984-09-01

    We report the case of an infant with hypoglycemia, progressive lactic acidosis, an increased serum lactate/pyruvate ratio, and elevated plasma alanine, who had a moderate to profound decrease in the ability of mitochondria from four organs to oxidize pyruvate, malate plus glutamate, citrate, and other NAD+-linked respiratory substrates. The capacity to oxidize the flavin adenine dinucleotide-linked substrate, succinate, was normal. The most pronounced deficiency was in skeletal muscle, the least in kidney mitochondria. Enzymatic assays on isolated mitochondria ruled out defects in complexes II, III, and IV of the respiratory chain. Further studies showed that the defect was localized in the inner membrane mitochondrial NADH-ubiquinone oxidoreductase (complex I). When ferricyanide was used as an artificial electron acceptor, complex I activity was normal, indicating that electrons from NADH could reduce the flavin mononucleotide cofactor. However, electron paramagnetic resonance spectroscopy performed on liver submitochondrial particles showed an almost total loss of the iron-sulfur clusters characteristic of complex I, whereas normal signals were noted for other mitochondrial iron-sulfur clusters. This infant is presented as the first reported case of congenital lactic acidosis caused by a deficiency of the iron-sulfur clusters of complex I of the mitochondrial electron transport chain.

  9. Glutathione, Glutaredoxins, and Iron.

    Science.gov (United States)

    Berndt, Carsten; Lillig, Christopher Horst

    2017-11-20

    Glutathione (GSH) is the most abundant cellular low-molecular-weight thiol in the majority of organisms in all kingdoms of life. Therefore, functions of GSH and disturbed regulation of its concentration are associated with numerous physiological and pathological situations. Recent Advances: The function of GSH as redox buffer or antioxidant is increasingly being questioned. New functions, especially functions connected to the cellular iron homeostasis, were elucidated. Via the formation of iron complexes, GSH is an important player in all aspects of iron metabolism: sensing and regulation of iron levels, iron trafficking, and biosynthesis of iron cofactors. The variety of GSH coordinated iron complexes and their functions with a special focus on FeS-glutaredoxins are summarized in this review. Interestingly, GSH analogues that function as major low-molecular-weight thiols in organisms lacking GSH resemble the functions in iron homeostasis. Since these iron-related functions are most likely also connected to thiol redox chemistry, it is difficult to distinguish between mechanisms related to either redox or iron metabolisms. The ability of GSH to coordinate iron in different complexes with or without proteins needs further investigation. The discovery of new Fe-GSH complexes and their physiological functions will significantly advance our understanding of cellular iron homeostasis. Antioxid. Redox Signal. 27, 1235-1251.

  10. Chemical speciation and equilibria of some nucleic acid compounds and their iron(III) complexes

    Science.gov (United States)

    Masoud, Mamdouh S.; Abd El-Kaway, Marwa Y.; Hindawy, Ahmed M.; Soayed, Amina A.

    The pH effect on electronic absorption spectra of some biologically active nucleic acid constituents have been studied at room temperature and the mechanism of ionization was explained. These compounds are of two categories (pyrimidines: [barbital; 5,5'-diethyl-barbituric acid], [SBA; 4,6-dihydroxy-2-mercapto-pyrimidin], [NBA; 5-nitro-2,4,6(1H,3H,5H)-pyrimidine trione] and [TU; 2,3-dihydro-2-thioxo-pyrimidin-4(1H)-one]) and (purines: [adenine; 6-amino purine], its [Schiff bases derived from adenine-acetylacetone; (Z)-4-(7H-purin-6-ylimino)pentan-2-one) and adenine-salicylaldehyde; 2-((7H-purin-6-ylimino) methyl) phenol] and its [Azo derived from adenine-resorcinol; 4-((7H-purin-6-yl)-diazenyl) benzene-1,3-diol]. The phenomena of tautomerization assigned different tautomers. Different spectrophotometric methods are applied to evaluate the pK's values that explained with their molecular structures. The interaction of Fe3+ with some selected pyrimidines (barbital, NBA and SBA) was explained using familiar six spectrophotometric methods. The data typified the existence of different absorbing species with the different stoichiometries 1:1, 1:2, 1:3 and 2:3. The stability constant of the complexes was computed. More approach was deduced to assign the existence of different species applying the distribution diagrams.

  11. Architecture of the Yeast Mitochondrial Iron-Sulfur Cluster Assembly Machinery: THE SUB-COMPLEX FORMED BY THE IRON DONOR, Yfh1 PROTEIN, AND THE SCAFFOLD, Isu1 PROTEIN.

    Science.gov (United States)

    Ranatunga, Wasantha; Gakh, Oleksandr; Galeano, Belinda K; Smith, Douglas Y; Söderberg, Christopher A G; Al-Karadaghi, Salam; Thompson, James R; Isaya, Grazia

    2016-05-06

    The biosynthesis of Fe-S clusters is a vital process involving the delivery of elemental iron and sulfur to scaffold proteins via molecular interactions that are still poorly defined. We reconstituted a stable, functional complex consisting of the iron donor, Yfh1 (yeast frataxin homologue 1), and the Fe-S cluster scaffold, Isu1, with 1:1 stoichiometry, [Yfh1]24·[Isu1]24 Using negative staining transmission EM and single particle analysis, we obtained a three-dimensional reconstruction of this complex at a resolution of ∼17 Å. In addition, via chemical cross-linking, limited proteolysis, and mass spectrometry, we identified protein-protein interaction surfaces within the complex. The data together reveal that [Yfh1]24·[Isu1]24 is a roughly cubic macromolecule consisting of one symmetric Isu1 trimer binding on top of one symmetric Yfh1 trimer at each of its eight vertices. Furthermore, molecular modeling suggests that two subunits of the cysteine desulfurase, Nfs1, may bind symmetrically on top of two adjacent Isu1 trimers in a manner that creates two putative [2Fe-2S] cluster assembly centers. In each center, conserved amino acids known to be involved in sulfur and iron donation by Nfs1 and Yfh1, respectively, are in close proximity to the Fe-S cluster-coordinating residues of Isu1. We suggest that this architecture is suitable to ensure concerted and protected transfer of potentially toxic iron and sulfur atoms to Isu1 during Fe-S cluster assembly. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Applying a modified Donnan model to describe the surface complexation of chromate to iron oxyhydroxide agglomerates with heteromorphous pores.

    Science.gov (United States)

    Wei, Zongsu; Semiat, Raphael

    2017-11-15

    In this study, a modified Donnan model (mDM) is incorporated into surface complexation model (SCM) to better understand the physicochemical processes for adsorption of hexavalent chromium, Cr(VI), on porous iron oxyhydroxide agglomerates (IOAs). The mDM includes a chemical potential term μ att to account for ionic transport and electrostatic interaction in micropores (d mi 2nm) demonstrating high Cr(VI) adsorption in a broad range of ionic strengths. The batch data was then fitted with Donnan model in PHREEQC to obtain Stern (ψ S ) and Donnan (ψ D ) potentials used for μ att calculation. The decreasing μ att values with ionic strength indicated obstructing effect of electrolyte ions on Cr(VI) uptake in micropores. Finally, the ionic activity coefficients and reaction constants were corrected using Pitzer model due to the high level electrolytes accumulated in the Donnan layer through osmotic and electrostatic attraction. Results of this study have captured the effects of inner structure of IOAs on Cr(VI) uptake and quantitatively discerned the contribution of micropores and macropores for adsorption reactions at different ionic strengths. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. The mechanism for catalytic hydrosilylation by bis(imino)pyridine iron olefin complexes supported by broken symmetry density functional theory.

    Science.gov (United States)

    Lam, Yan Choi; Nielsen, Robert J; Goddard, William A; Dash, Aswini K

    2017-09-26

    Density functional theory (DFT, B3LYP-D3 with implicit solvation in toluene) was used to investigate the mechanisms of olefin hydrosilylation catalyzed by PDI(Fe) (bis(imino)pyridine iron) complexes, where PDI = 2,6-(ArN[double bond, length as m-dash]CMe) 2 (C 5 H 3 N) with Ar = 2,6-R 2 -C 6 H 3 . We find that the rate-determining step for hydrosilylation is hydride migration from Et 3 SiH onto the Fe-bound olefin to form (PDI)Fe(alkyl)(SiEt 3 ). This differs from the mechanism for the Pt Karstedt catalyst in that there is no prior Si-H oxidative addition onto the Fe center. (PDI)Fe(alkyl)(SiEt 3 ) then undergoes C-Si reductive elimination to form (PDI)Fe, which coordinates an olefin ligand to regenerate the resting state (PDI)Fe(olefin). In agreement with experimental observations, we found that anti-Markovnikov hydride migration has a 5.1 kcal mol -1 lower activation enthalpy than Markovnikov migration. This system has an unusual anti-ferromagnetic coupling between high spin electrons on the Fe center and the unpaired spin in the pi system of the non-innocent redox-active PDI ligand. To describe this with DFT, we used the "broken-symmetry" approach to establish the ground electronic and spin state of intermediates and transition states over the proposed catalytic cycles.

  14. Photocatalytic hydrogen generation from water with iron carbonyl phosphine complexes: improved water reduction catalysts and mechanistic insights.

    Science.gov (United States)

    Gärtner, Felix; Boddien, Albert; Barsch, Enrico; Fumino, Koichi; Losse, Sebastian; Junge, Henrik; Hollmann, Dirk; Brückner, Angelika; Ludwig, Ralf; Beller, Matthias

    2011-05-27

    An extended study of a novel visible-light-driven water reduction system containing an iridium photosensitizer, an in situ iron(0) phosphine water reduction catalyst (WRC), and triethylamine as sacrificial reductant is described. The influences of solvent composition, ligand, ligand-to-metal ratio, and pH were studied. The use of monodentate phosphine ligands led to improved activity of the WRC. By applying a WRC generated in situ from Fe(3) (CO)(12) and tris[3,5-bis(trifluoromethyl)phenyl]phosphine (P[C(6)H(3)(CF(3))(2)](3), Fe(3)(CO)(12)/PR(3)=1:1.5), a catalyst turnover number of more than 1500 was obtained, which constitutes the highest activity reported for any Fe WRC. The maximum incident photon to hydrogen efficiency obtained was 13.4% (440 nm). It is demonstrated that the evolved H(2) flow (0.23 mmol H(2) h(-1) mg(-1) Fe(3)(CO)(12)) is sufficient to be used in polymer electrolyte membrane fuel cells, which generate electricity directly from water with visible light. Mechanistic studies by NMR spectroscopy, in situ IR spectroscopy, and DFT calculations allow for an improved understanding of the mechanism. With respect to the Fe WRC, the complex [HNEt(3)](+)[HFe(3)(CO)(11)](-) was identified as the key intermediate during the catalytic cycle, which led to light-driven hydrogen generation from water. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Use of Iron (II Salts and Complexes for the Production of Soil Amendments from Organic Solid Wastes

    Directory of Open Access Journals (Sweden)

    Amerigo Beneduci

    2012-01-01

    Full Text Available A method to obtain rapidly stabilized composts for crops from solid organic wastes is evaluated. Here we used a laboratory scale reaction chamber where solid waste treatment was performed under strictly controlled temperature and pressure conditions. The row organic waste was mixed with acid solutions containing iron (II ions either in the fully hydrated form or in the form of complexes with the diethylentriaminopentaacetic acid. Data from elemental analysis distribution and GC/MS analysis of the polar and non polar dissolved organic matter, clearly showed that Fe(II ions significantly enhance organic substrate oxidation of the initial solid waste, compared to a material obtained without the addition of the Fe(II ions to the raw organic matrix. These results suggest that Fe(II ions might be involved in a catalytic oxidation pathway that would be activated under the experimental conditions used. The extent of the oxidation process was evaluated by the value of the C/N ratio and, qualitatively, by the molecular composition of the dissolved organic matter. After about 6 hours of incubation, dark-brown and dry organic matrices were obtained with C/N ratio as low as 12 and a high degree of oxidative decomposition into low-molecular-weight compounds at high oxidation state.

  16. Monitoring the injection of microscale zero-valent iron particles for groundwater remediation by means of complex electrical conductivity imaging

    Science.gov (United States)

    Flores Orozco, A.; Velimirovic, M.; Tosco, T.; Kemna, A.; Sapion, H.; Klaas, N.; Sethi, R.; Bastiaens, L.

    2015-12-01

    The injection of nano- and microscale zerovalent iron (ZVI) particles has emerged as a promising technique for groundwater remediation. In particular, ZVI injections offer a suitable alternative for the remediation of areas not accessible with other techniques, such as areas characterized by low hydraulic conductivity. In such cases, the injection is performed at high pressure in order to create preferential flow paths (i.e., fractures). Particle injection via fracturing demands an adequate monitoring of the ZVI delivery to track the migration path of the particles as well as to delineate the extension and distribution of the iron slurry. However, characterization of ZVI injections is to date based mainly on the analysis of groundwater and soil samples, thus, limiting the spatio-temporal resolution of the investigation and making it not suitable for real-time monitoring. To overcome this, here we present the application of the complex conductivity (CC) imaging method to characterize the delivery of guar gum stabilized microscale ZVI (GG-mZVI) particles during a field-scale injection by hydraulic fracturing. Our results demonstrated that CC images provide not only an improved characterization of the contaminant distribution, but also valuable information to identify the migration pathway of the injected GG-mZVI. The relatively short acquisition time of CC datasets permitted to obtain monitoring data with enhanced temporal resolution, i.e., after each injection (every ~15 minutes), while still covering an extended area of investigation in comparison to conventional geochemical monitoring by means of soil and water samples. As presented in Figure 1, the CC images revealed an increase (~20%) in the induced electrical polarization (Φ), upon delivery of ZVI into the targeted area, due to the accumulation of ZVI. Furthermore, larger changes (>50%) occurred in shallow sediments, a few meters away from the injection, suggesting the migration of particles through

  17. S-Nitrosylation and uncompetitive/fast off-rate (UFO) drug therapy in neurodegenerative disorders of protein misfolding.

    Science.gov (United States)

    Nakamura, T; Lipton, S A

    2007-07-01

    Although activation of glutamate receptors is essential for normal brain function, excessive activity leads to a form of neurotoxicity known as excitotoxicity. Key mediators of excitotoxic damage include overactivation of N-methyl-D-aspartate (NMDA) receptors, resulting in excessive Ca(2+) influx with production of free radicals and other injurious pathways. Overproduction of free radical nitric oxide (NO) contributes to acute and chronic neurodegenerative disorders. NO can react with cysteine thiol groups to form S-nitrosothiols and thus change protein function. S-nitrosylation can result in neuroprotective or neurodestructive consequences depending on the protein involved. Many neurodegenerative diseases manifest conformational changes in proteins that result in misfolding and aggregation. Our recent studies have linked nitrosative stress to protein misfolding and neuronal cell death. Molecular chaperones - such as protein-disulfide isomerase, glucose-regulated protein 78, and heat-shock proteins - can provide neuroprotection by facilitating proper protein folding. Here, we review the effect of S-nitrosylation on protein function under excitotoxic conditions, and present evidence that NO contributes to degenerative conditions by S-nitrosylating-specific chaperones that would otherwise prevent accumulation of misfolded proteins and neuronal cell death. In contrast, we also review therapeutics that can abrogate excitotoxic damage by preventing excessive NMDA receptor activity, in part via S-nitrosylation of this receptor to curtail excessive activity.

  18. Mechanochemistry of the 5f-element compounds. Part 3. Mechanochemically stimulated formation of nitrosyl uranyl nitrate

    International Nuclear Information System (INIS)

    Kovacheva, P.; Minkova, N.; Todorovsky, D.; Radev, D.

    2007-01-01

    The effect of the mechanical treatment of UO 2 (NO 3 ) 2 x 6H 2 O in a planetary ball mill in air and as a suspension in toluene has been studied. The Xray diffractometry results strongly suggest that part of the mechanoactivated material is transformed in nitrosyl uranyl nitrate. (author)

  19. Protein S-nitrosylation and denitrosylation in the mouse spinal cord upon injury of the sciatic nerve

    NARCIS (Netherlands)

    Scheving, R.; Wittig, I.; Heide, H.; Albuquerque, B.; Steger, M.; Brandt, U.; Tegeder, I.

    2012-01-01

    Nitric oxide is a pain signaling molecule and exerts its influence through two primary pathways: by stimulation of soluble guanylylcyclase and by direct S-nitrosylation (SNO) of target proteins. We assessed in the spinal cord the SNO-proteome with two methods, two-dimensional S-nitrosothiol

  20. The Role of S-Nitrosylation and S-Glutathionylation of Protein Disulphide Isomerase in Protein Misfolding and Neurodegeneration

    Directory of Open Access Journals (Sweden)

    M. Halloran

    2013-01-01

    Full Text Available Neurodegenerative diseases involve the progressive loss of neurons, and a pathological hallmark is the presence of abnormal inclusions containing misfolded proteins. Although the precise molecular mechanisms triggering neurodegeneration remain unclear, endoplasmic reticulum (ER stress, elevated oxidative and nitrosative stress, and protein misfolding are important features in pathogenesis. Protein disulphide isomerase (PDI is the prototype of a family of molecular chaperones and foldases upregulated during ER stress that are increasingly implicated in neurodegenerative diseases. PDI catalyzes the rearrangement and formation of disulphide bonds, thus facilitating protein folding, and in neurodegeneration may act to ameliorate the burden of protein misfolding. However, an aberrant posttranslational modification of PDI, S-nitrosylation, inhibits its protective function in these conditions. S-nitrosylation is a redox-mediated modification that regulates protein function by covalent addition of nitric oxide- (NO- containing groups to cysteine residues. Here, we discuss the evidence for abnormal S-nitrosylation of PDI (SNO-PDI in neurodegeneration and how this may be linked to another aberrant modification of PDI, S-glutathionylation. Understanding the role of aberrant S-nitrosylation/S-glutathionylation of PDI in the pathogenesis of neurodegenerative diseases may provide insights into novel therapeutic interventions in the future.

  1. Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide.

    Science.gov (United States)

    Crack, Jason C; Green, Jeffrey; Thomson, Andrew J; Le Brun, Nick E

    2014-10-21

    recognized. This remarkable feature suggested that the original [4Fe-4S] cluster can be restored using persulfide as the source of sulfide ion. We have demonstrated that only iron and a source of electrons are required to promote efficient conversion back from the [2Fe-2S] to the [4Fe-4S] form. We propose this as a novel in vivo repair mechanism that does not require the intervention of an iron-sulfur cluster biogenesis pathway. A number of iron-sulfur regulators have evolved to function as sensors of NO. Although it has long been known that the iron-sulfur clusters of many phylogenetically unrelated proteins are vulnerable to attack by NO, our recent studies of Wbl proteins and FNR have provided new insights into the mechanism of cluster nitrosylation, which overturn the commonly accepted view that the product is solely a mononuclear iron dinitrosyl complex (known as a DNIC). The major reaction is a rapid, multiphase process involving stepwise addition of up to eight NO molecules per [4Fe-4S] cluster. The major iron nitrosyl product is EPR silent and has optical characteristics similar to Roussin's red ester, [Fe2(NO)4(RS)2] (RRE), although a species similar to Roussin's black salt, [Fe4(NO)7(S)3](-) (RBS) cannot be ruled out. A major future challenge will be to clarify the nature of these species.

  2. Iron Chelation

    Science.gov (United States)

    Skip to main content Menu Donate Treatments Therapies Iron Chelation Iron chelation therapy is the main treatment ... have iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you ...

  3. Iron L2,3-Edge X-ray Absorption and X-ray Magnetic Circular Dichroism Studies of Molecular Iron Complexes with Relevance to the FeMoco and FeVco Active Sites of Nitrogenase.

    Science.gov (United States)

    Kowalska, Joanna K; Nayyar, Brahamjot; Rees, Julian A; Schiewer, Christine E; Lee, Sonny C; Kovacs, Julie A; Meyer, Franc; Weyhermüller, Thomas; Otero, Edwige; DeBeer, Serena

    2017-07-17

    Herein, a systematic study of a series of molecular iron model complexes has been carried out using Fe L 2,3 -edge X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopies. This series spans iron complexes of increasing complexity, starting from ferric and ferrous tetrachlorides ([FeCl 4 ] -/2- ), to ferric and ferrous tetrathiolates ([Fe(SR) 4 ] -/2- ), to diferric and mixed-valent iron-sulfur complexes [Fe 2 S 2 R 4 ] 2-/3- . This test set of compounds is used to evaluate the sensitivity of both Fe L 2,3 -edge XAS and XMCD spectroscopy to oxidation state and ligation changes. It is demonstrated that the energy shift and intensity of the L 2,3 -edge XAS spectra depends on both the oxidation state and covalency of the system; however, the quantitative information that can be extracted from these data is limited. On the other hand, analysis of the Fe XMCD shows distinct changes in the intensity at both L 3 and L 2 edges, depending on the oxidation state of the system. It is also demonstrated that the XMCD intensity is modulated by the covalency of the system. For mononuclear systems, the experimental data are correlated with atomic multiplet calculations in order to provide insights into the experimental observations. Finally, XMCD is applied to the tetranuclear heterometal-iron-sulfur clusters [MFe 3 S 4 ] 3+/2+ (M = Mo, V), which serve as structural analogues of the FeMoco and FeVco active sites of nitrogenase. It is demonstrated that the XMCD data can be utilized to obtain information on the oxidation state distribution in complex clusters that is not readily accessible for the Fe L 2,3 -edge XAS data alone. The advantages of XMCD relative to standard K-edge and L 2,3 -edge XAS are highlighted. This study provides an important foundation for future XMCD studies on complex (bio)inorganic systems.

  4. Nonanuclear Spin-Crossover Complex Containing Iron(II) and Iron(III) Based on a 2,6-Bis(pyrazol-1-yl)pyridine Ligand Functionalized with a Carboxylate Group.

    Science.gov (United States)

    Abhervé, Alexandre; Recio-Carretero, María José; López-Jordà, Maurici; Clemente-Juan, Juan Modesto; Canet-Ferrer, Josep; Cantarero, Andrés; Clemente-León, Miguel; Coronado, Eugenio

    2016-09-19

    The synthesis and magnetostructural characterization of [Fe(III)3(μ3-O)(H2O)3[Fe(II)(bppCOOH)(bppCOO)]6](ClO4)13·(CH3)2CO)6·(solvate) (2) are reported. This compound is obtained as a secondary product during synthesis of the mononuclear complex [Fe(II)(bppCOOH)2](ClO4)2 (1). The single-crystal X-ray diffraction structure of 2 shows that it contains the nonanuclear cluster of the formula [Fe(III)3(μ3-O)(H2O)3[Fe(II)(bppCOOH)(bppCOO)]6](13+), which is formed by a central Fe(III)3O core coordinated to six partially deprotonated [Fe(II)(bppCOOH)(bppCOO)](+) complexes. Raman spectroscopy studies on single crystals of 1 and 2 have been performed to elucidate the spin and oxidation states of iron in 2. These studies and magnetic characterization indicate that most of the iron(II) complexes of 2 remain in the low-spin (LS) state and present a gradual and incomplete spin crossover above 300 K. On the other hand, the Fe(III) trimer shows the expected antiferromagnetic behavior. From the structural point of view, 2 represents the first example in which bppCOO(-) acts as a bridging ligand, thus forming a polynuclear magnetic complex.

  5. Protein nitration and nitrosylation by NO-donating aspirin in colon cancer cells: Relevance to its mechanism of action

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Jennie L.; Ji, Ping; Ouyang, Nengtai [Division of Cancer Prevention, Stony Brook University, HSC, T17-080, Stony Brook, NY 11794-8173 (United States); Kopelovich, Levy [Division of Cancer Prevention NCI, NIH, Bethesda, MD (United States); Rigas, Basil, E-mail: basil.rigas@stonybrook.edu [Division of Cancer Prevention, Stony Brook University, HSC, T17-080, Stony Brook, NY 11794-8173 (United States)

    2011-06-10

    Nitric oxide-donating aspirin (NO-ASA) is a promising agent for cancer prevention. Although studied extensively, its molecular targets and mechanism of action are still unclear. S-nitrosylation of signaling proteins is emerging as an important regulatory mechanism by NO. Here, we examined whether S-nitrosylation of the NF-{kappa}B, p53, and Wnt signaling proteins by NO-ASA might explain, in part, its mechanism of action in colon cancer. NO-ASA releases significant amounts of NO detected intracellularly in HCT116 and HT-29 colon cells. Using a modified biotin switch assay we demonstrated that NO-ASA S-nitrosylates the signaling proteins p53, {beta}-catenin, and NF-{kappa}B, in colon cancer cells in a time- and concentration-dependent manner. NO-ASA suppresses NF-{kappa}B binding to its cognate DNA oligonucleotide, which occurs without changes in the nuclear levels of the NF-{kappa}B subunits p65 and p50 and is reversed by dithiothreitol that reduces -S-NO to -SH. In addition to S-nitrosylation, we documented both in vitro and in vivo widespread nitration of tyrosine residues of cellular proteins in response to NO-ASA. Our results suggest that the increased intracellular NO levels following treatment with NO-ASA modulate cell signaling by chemically modifying key protein members of signaling cascades. We speculate that S-nitrosylation and tyrosine nitration are responsible, at least in part, for the inhibitory growth effect of NO-ASA on cancer cell growth and that this may represent a general mechanism of action of NO-releasing agents.

  6. Iron, copper, and manganese complexes with in vitro superoxide dismutase and/or catalase activities that keep Saccharomyces cerevisiae cells alive under severe oxidative stress.

    Science.gov (United States)

    Ribeiro, Thales P; Fernandes, Christiane; Melo, Karen V; Ferreira, Sarah S; Lessa, Josane A; Franco, Roberto W A; Schenk, Gerhard; Pereira, Marcos D; Horn, Adolfo

    2015-03-01

    Due to their aerobic lifestyle, eukaryotic organisms have evolved different strategies to overcome oxidative stress. The recruitment of some specific metalloenzymes such as superoxide dismutases (SODs) and catalases (CATs) is of great importance for eliminating harmful reactive oxygen species (hydrogen peroxide and superoxide anion). Using the ligand HPClNOL {1-[bis(pyridin-2-ylmethyl)amino]-3-chloropropan-2-ol}, we have synthesized three coordination compounds containing iron(III), copper(II), and manganese(II) ions, which are also present in the active site of the above-noted metalloenzymes. These compounds were evaluated as SOD and CAT mimetics. The manganese and iron compounds showed both SOD and CAT activities, while copper showed only SOD activity. The copper and manganese in vitro SOD activities are very similar (IC50~0.4 μmol dm(-3)) and about 70-fold higher than those of iron. The manganese compound showed CAT activity higher than that of the iron species. Analyzing their capacity to protect Saccharomyces cerevisiae cells against oxidative stress (H2O2 and the O2(•-) radical), we observed that all compounds act as antioxidants, increasing the resistance of yeast cells mainly due to a reduction of lipid oxidation. Especially for the iron compound, the data indicate complete protection when wild-type cells were exposed to H2O2 or O2(•-) species. Interestingly, these compounds also compensate for both superoxide dismutase and catalase deficiencies; their antioxidant activity is metal ion dependent, in the order iron(III)>copper(II)>manganese(II). The protection mechanism employed by the complexes proved to be independent of the activation of transcription factors (such as Yap1, Hsf1, Msn2/Msn4) and protein synthesis. There is no direct relation between the in vitro and the in vivo antioxidant activities. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. The Yeast Iron Regulatory Proteins Grx3/4 and Fra2 Form Heterodimeric Complexes Containing a [2Fe-2S] Cluster with Cysteinyl and Histidyl Ligation

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.; Mapolelo, D; Dingra, N; Naik, S; Lees, N; Hoffman, B; Riggs-Gelasco, P; Huynh, B; Johnson, M; Outten, C

    2009-01-01

    The transcription of iron uptake and storage genes in Saccharomyces cerevisiae is primarily regulated by the transcription factor Aft1. Nucleocytoplasmic shuttling of Aft1 is dependent upon mitochondrial Fe-S cluster biosynthesis via a signaling pathway that includes the cytosolic monothiol glutaredoxins (Grx3 and Grx4) and the BolA homologue Fra2. However, the interactions between these proteins and the iron-dependent mechanism by which they control Aft1 localization are unclear. To reconstitute and characterize components of this signaling pathway in vitro, we have overexpressed yeast Fra2 and Grx3/4 in Escherichia coli. We have shown that coexpression of recombinant Fra2 with Grx3 or Grx4 allows purification of a stable [2Fe-2S]{sup 2+} cluster-containing Fra2-Grx3 or Fra2-Grx4 heterodimeric complex. Reconstitution of a [2Fe-2S] cluster on Grx3 or Grx4 without Fra2 produces a [2Fe-2S]-bridged homodimer. UV?visible absorption and CD, resonance Raman, EPR, ENDOR, M{umlt o}ssbauer, and EXAFS studies of [2Fe-2S] Grx3/4 homodimers and the [2Fe-2S] Fra2-Grx3/4 heterodimers indicate that inclusion of Fra2 in the Grx3/4 Fe-S complex causes a change in the cluster stability and coordination environment. Taken together, our analytical, spectroscopic, and mutagenesis data indicate that Grx3/4 and Fra2 form a Fe-S-bridged heterodimeric complex with Fe ligands provided by the active site cysteine of Grx3/4, glutathione, and a histidine residue. Overall, these results suggest that the ability of the Fra2-Grx3/4 complex to assemble a [2Fe-2S] cluster may act as a signal to control the iron regulon in response to cellular iron status in yeast.

  8. The first iron(III) complexes with cyclin-dependent kinase inhibitors: Magnetic, spectroscopic (IR, ES+ MS, NMR, Fe-57 Mossbauer), theoretical, and biological activity studies

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Zdeněk; Popa, Igor; Čajan, Michal; Zbořil, R.; Kryštof, Vladimír; Mikulík, J.

    2010-01-01

    Roč. 104, č. 4 (2010), s. 405-417 ISSN 0162-0134 R&D Projects: GA MŠk 1M0512; GA ČR GA301/08/1649 Institutional research plan: CEZ:AV0Z50380511 Keywords : Iron(III) complexes * 57Fe Mössbauer spectroscopy * CDK inhibition Subject RIV: CA - Inorganic Chemistry Impact factor: 3.317, year: 2010

  9. Integrating a Smartphone and Molecular Modeling for Determining the Binding Constant and Stoichiometry Ratio of the Iron(II)-Phenanthroline Complex: An Activity for Analytical and Physical Chemistry Laboratories

    Science.gov (United States)

    de Morais, Camilo de L. M.; Silva, Se´rgio R. B.; Vieira, Davi S.; Lima, Ka´ssio M. G.

    2016-01-01

    The binding constant and stoichiometry ratio for the formation of iron(II)-(1,10-phenanthroline) or iron(II)-o-phenanthroline complexes has been determined by a combination of a low-cost analytical method using a smartphone and a molecular modeling method as a laboratory experiment designed for analytical and physical chemistry courses. Intensity…

  10. RBC-NOS-Dependent S-Nitrosylation of Cytoskeletal Proteins Improves RBC Deformability

    Science.gov (United States)

    Grau, Marijke; Pauly, Sebastian; Ali, Jamal; Walpurgis, Katja; Thevis, Mario; Bloch, Wilhelm; Suhr, Frank

    2013-01-01

    Background Red blood cells (RBC) possess a nitric oxide synthase (RBC-NOS) whose activation depends on the PI3-kinase/Akt kinase pathway. RBC-NOS-produced NO exhibits important biological functions like maintaining RBC deformability. Until now, the cellular target structure for NO, to exert its influence on RBC deformability, remains unknown. In the present study we analyzed the modification of RBC-NOS activity by pharmacological treatments, the resulting influence on RBC deformability and provide first evidence for possible target proteins of RBC-NOS-produced NO in the RBC cytoskeletal scaffold. Methods/Findings Blood from fifteen male subjects was incubated with the NOS substrate L-arginine to directly stimulate enzyme activity. Direct inhibition of enzyme activity was induced by L-N5-(1-Iminoethyl)-ornithin (L-NIO). Indirect stimulation and inhibition of RBC-NOS were achieved by applying insulin and wortmannin, respectively, substances known to affect PI3-kinase/Akt kinase pathway. The NO donor sodium nitroprusside (SNP) and the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) were additionally applied as NO positive and negative controls, respectively. Immunohistochemical staining was used to determine phosphorylation and thus activation of RBC-NOS. As a marker for NO synthesis nitrite was measured in plasma and RBCs using chemiluminescence detection. S-nitrosylation of erythrocyte proteins was determined by biotin switch assay and modified proteins were identified using LC-MS. RBC deformability was determined by ektacytometry. The data reveal that activated RBC-NOS leads to increased NO production, S-nitrosylation of RBC proteins and RBC deformability, whereas RBC-NOS inhibition resulted in contrary effects. Conclusion/Significance This study first-time provides strong evidence that RBC-NOS-produced NO modifies RBC deformability through direct S-nitrosylation of cytoskeleton proteins, most likely α- and β-spectrins. Our

  11. Low-pressure hydrogenation of carbon dioxide catalyzed by an iron pincer complex exhibiting noble metal activity.

    Science.gov (United States)

    Langer, Robert; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Ben-David, Yehoshoa; Milstein, David

    2011-10-10

    A highly active iron catalyst for the hydrogenation of carbon dioxide and bicarbonates works under remarkably low pressures and achieves activities similar to some of the best noble metal catalysts. A mechanism is proposed involving the direct attack of an iron trans-dihydride on carbon dioxide, followed by ligand exchange and dihydrogen coordination. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A comprehensive test set of epoxidation rate constants for iron(iv)-oxo porphyrin cation radical complexes.

    Science.gov (United States)

    Sainna, Mala A; Kumar, Suresh; Kumar, Devesh; Fornarini, Simonetta; Crestoni, Maria Elisa; de Visser, Sam P

    2015-02-01

    -set of experimental reaction rates of iron(iv)-oxo porphyrin cation radical complexes, so far unprecedented in the gas-phase, providing a benchmark for calibration studies using computational techniques. Preliminary computational results presented here confirm the observed trends excellently and rationalize the reactivities within the framework of thermochemical considerations and valence bond schemes.

  13. The ubiquity of iron.

    Science.gov (United States)

    Frey, Perry A; Reed, George H

    2012-09-21

    The importance of iron in living systems can be traced to the many complexes within which it is found, to its chemical mobility in undergoing oxidation-reduction reactions, and to the abundance of iron in Earth's crust. Iron is the most abundant element, by mass, in the Earth, constituting about 80% of the inner and outer cores of Earth. The molten outer core is about 8000 km in diameter, and the solid inner core is about 2400 km in diameter. Iron is the fourth most abundant element in Earth's crust. It is the chemically functional component of mononuclear iron complexes, dinuclear iron complexes, [2Fe-2S] and [4Fe-4S] clusters, [Fe-Ni-S] clusters, iron protophorphyrin IX, and many other complexes in protein biochemistry. Metals such as nickel, cobalt, copper, and manganese are present in the crust and could in principle function chemically in place of iron, but they are scarce in Earth's crust. Iron is plentiful because of its nuclear stability in stellar nuclear fusion reactions. It seems likely that other solid planets, formed by the same processes as Earth, would also foster the evolution of life and that iron would be similarly important to life on those planets as it is on Earth.

  14. Serum levels of carbonylated and nitrosylated proteins in mobbing victims with workplace adjustment disorders.

    Science.gov (United States)

    Di Rosa, A E; Gangemi, S; Cristani, M; Fenga, C; Saitta, S; Abenavoli, E; Imbesi, S; Speciale, A; Minciullo, P L; Spatari, G; Abbate, S; Saija, A; Cimino, F

    2009-12-01

    Today the most important problem in the work place is psychological abuse, which may affect the health because of high levels of stress and anxiety. There is evidence that most psychiatric disorders are associated with increased oxidative stress but nothing is reported about the presence of oxidative stress in mobbing victims. This study has been carried out in a group of 19 patients affected by workplace mobbing-due adjustment disorders, in comparison with 38 healthy subjects, to evaluate whether oxidative stress may be induced by mobbing. Serum levels of protein carbonyl groups and of nitrosylated proteins, biological markers of oxidative stress conditions, were higher than those measured in healthy subjects. These findings may contribute to a better understanding of the redox homeostasis dysregulation occurring in victims of workplace mobbing.

  15. Hydrogen Sulfide Increases Nitric Oxide Production and Subsequent S-Nitrosylation in Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Ping-Ho Chen

    2014-01-01

    Full Text Available Hydrogen sulfide (H2S and nitric oxide (NO, two endogenous gaseous molecules in endothelial cells, got increased attention with respect to their protective roles in the cardiovascular system. However, the details of the signaling pathways between H2S and NO in endothelia cells remain unclear. In this study, a treatment with NaHS profoundly increased the expression and the activity of endothelial nitric oxide synthase. Elevated gaseous NO levels were observed by a novel and specific fluorescent probe, 5-amino-2-(6-hydroxy-3-oxo-3H-xanthen-9-ylbenzoic acid methyl ester (FA-OMe, and quantified by flow cytometry. Further study indicated an increase of upstream regulator for eNOS activation, AMP-activated protein kinase (AMPK, and protein kinase B (Akt. By using a biotin switch, the level of NO-mediated protein S-nitrosylation was also enhanced. However, with the addition of the NO donor, NOC-18, the expressions of cystathionine-γ-lyase, cystathionine-β-synthase, and 3-mercaptopyruvate sulfurtransferase were not changed. The level of H2S was also monitored by a new designed fluorescent probe, 4-nitro-7-thiocyanatobenz-2-oxa-1,3-diazole (NBD-SCN with high specificity. Therefore, NO did not reciprocally increase the expression of H2S-generating enzymes and the H2S level. The present study provides an integrated insight of cellular responses to H2S and NO from protein expression to gaseous molecule generation, which indicates the upstream role of H2S in modulating NO production and protein S-nitrosylation.

  16. Current understanding of iron homeostasis.

    Science.gov (United States)

    Anderson, Gregory J; Frazer, David M

    2017-12-01

    Iron is an essential trace element, but it is also toxic in excess, and thus mammals have developed elegant mechanisms for keeping both cellular and whole-body iron concentrations within the optimal physiologic range. In the diet, iron is either sequestered within heme or in various nonheme forms. Although the absorption of heme iron is poorly understood, nonheme iron is transported across the apical membrane of the intestinal enterocyte by divalent metal-ion transporter 1 (DMT1) and is exported into the circulation via ferroportin 1 (FPN1). Newly absorbed iron binds to plasma transferrin and is distributed around the body to sites of utilization with the erythroid marrow having particularly high iron requirements. Iron-loaded transferrin binds to transferrin receptor 1 on the surface of most body cells, and after endocytosis of the complex, iron enters the cytoplasm via DMT1 in the endosomal membrane. This iron can be used for metabolic functions, stored within cytosolic ferritin, or exported from the cell via FPN1. Cellular iron concentrations are modulated by the iron regulatory proteins (IRPs) IRP1 and IRP2. At the whole-body level, dietary iron absorption and iron export from the tissues into the plasma are regulated by the liver-derived peptide hepcidin. When tissue iron demands are high, hepcidin concentrations are low and vice versa. Too little or too much iron can have important clinical consequences. Most iron deficiency reflects an inadequate supply of iron in the diet, whereas iron excess is usually associated with hereditary disorders. These disorders include various forms of hemochromatosis, which are characterized by inadequate hepcidin production and, thus, increased dietary iron intake, and iron-loading anemias whereby both increased iron absorption and transfusion therapy contribute to the iron overload. Despite major recent advances, much remains to be learned about iron physiology and pathophysiology. © 2017 American Society for Nutrition.

  17. S-nitrosylation of the mitochondrial chaperone TRAP1 sensitizes hepatocellular carcinoma cells to inhibitors of succinate dehydrogenase

    DEFF Research Database (Denmark)

    Rizza, Salvatore; Montagna, Costanza; Cardaci, Simone

    2016-01-01

    degradation. As a result, GSNOR-deficient cells and tumors are highly sensitive to SDH inhibition, namely to α-tocopheryl succinate, an SDH-targeting molecule that induced RIP1/PARP1-mediated necroptosis and inhibited tumor growth. Our work provides a specific molecular signature of aberrant S....... We find that hepatocyte GSNOR deficiency is characterized by mitochondrial alteration and by marked increases in succinate dehydrogenase (SDH) levels and activity. We find that this depends on the selective S-nitrosylation of Cys(501) in the mitochondrial chaperone TRAP1, which mediates its......-nitrosylation in HCC, a novel molecular target in SDH, and a first-in-class therapy to treat the disease. Cancer Res; 76(14); 1-13. ©2016 AACR....

  18. Key role of organic complexation of iron in sustaining phytoplankton blooms in the Pine Island and Amundsen Polynyas (Southern Ocean)

    NARCIS (Netherlands)

    Thuroczy, Charles-Edouard; Alderkamp, Anne-Carlijn; Laan, Patrick; Gerringa, Loes J. A.; Mills, Matthew M.; Van Dijken, Gert L.; De Baar, Hein J. W.; Arrigo, Kevin R.

    2012-01-01

    Primary productivity in the Amundsen Sea (Southern Ocean) is among the highest in Antarctica. The summer phytoplankton bloom in 2009 lasted for > 70 days in both the Pine Island and Amundsen Polynyas. Such productive blooms require a large supply of nutrients, including the trace metal iron (Fe).

  19. Salicylate Detection by Complexation with Iron(III) and Optical Absorbance Spectroscopy: An Undergraduate Quantitative Analysis Experiment

    Science.gov (United States)

    Mitchell-Koch, Jeremy T.; Reid, Kendra R.; Meyerhoff, Mark E.

    2008-01-01

    An experiment for the undergraduate quantitative analysis laboratory involving applications of visible spectrophotometry is described. Salicylate, a component found in several medications, as well as the active by-product of aspirin decomposition, is quantified. The addition of excess iron(III) to a solution of salicylate generates a deeply…

  20. Measurement of S-nitrosylated Proteins in Tissues of Rats Fed Diets with Differing Levels of Nitrite

    Science.gov (United States)

    2011-12-01

    in tissue samples provided by Dr. Atkins . Overall, there were 4 groups of rats (1-control; 2-low nitrite/nitrate diet for 7 days; 3-low N/N diet ...DMPO) Measurement of S-nitrosylated Proteins in Tissues of Rats Fed Diets with Differing Levels of Nitrite Dr. Valerian Kagan University of...3 Introduction: According to the work accomplished by Dr. James Atkins at Walter Reed Army Institute of Research

  1. Trifluoperazine-Induced Suicidal Erythrocyte Death and S-Nitrosylation Inhibition, Reversed by the Nitric Oxide Donor Sodium Nitroprusside

    Directory of Open Access Journals (Sweden)

    Mehrdad Ghashghaeinia

    2017-08-01

    Full Text Available Background and Purpose: The high potency antipsychotic drug trifluoperazine (10-[3-(4-methyl-1-piperazinyl-propyl]-2-(trifluoromethyl-(10H-phenothiazine dihydrochloride; TFP may either counteract or promote suicidal cell death or apoptosis. Similar to apoptosis, erythrocytes may enter eryptosis, characterized by phosphatidylserine exposure at the cell surface and cell shrinkage. Eryptosis can be stimulated by an increase in cytoplasmic Ca2+ concentration ([Ca2+]i and inhibited by nitric oxide (NO. We explored whether TFP treatment of erythrocytes induces phosphatidylserine exposure, cell shrinkage, and calcium influx, whether it impairs S-nitrosylation and whether these effects are inhibited by NO. Methods: Phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, and protein nitrosylation from fluorescence switch of the Bodipy-TMR/Sypro Ruby signal. Results: Exposure of human erythrocytes to TFP significantly enhanced the percentage of annexin-V-binding cells, raised [Ca2+]i, and decreased S-nitrosylation. The effect of TFP on annexin-V-binding was not affected by removal of extracellular Ca2+ alone, but was significantly inhibited by pre-treatment with sodium nitroprusside (SNP, an effect significantly augmented by additional removal of extracellular Ca2+. A 3 hours treatment with 0.1 µM Ca2+ ionophore ionomycin triggered annexin-V-binding and cell shrinkage, effects fully reversed by removal of extracellular Ca2+. Conclusions: TFP induces eryptosis and decreases protein S-nitrosylation, effects blunted by nitroprusside. The effect of nitroprusside is attenuated in the presence of extracellular Ca2+.

  2. A new PC(sp(3))P ligand and its coordination chemistry with low-valent iron, cobalt and nickel complexes.

    Science.gov (United States)

    Zhu, Gengyu; Li, Xiaoyan; Xu, Guoqiang; Wang, Lin; Sun, Hongjian

    2014-06-21

    A new PC(sp(3))P ligand N,N'-bis(diphenylphosphino)dipyrromethane [PCH2P] (1) was prepared and its iron, cobalt and nickel chemistry was explored. Two pincer-type complexes [PCHP]Fe(H)(PMe3)2 (2) and [PCHP]Co(PMe3)2 (4) were synthesized in the reaction of with Fe(PMe3)4 and Co(Me)(PMe3)4. 1 reacted with Co(PMe3)4 and Ni(PMe3)4 to afford Co(0) and Ni(0) complexes [PCH2P]Co(PMe3)2 (3) and [PCH2P]Ni(PMe3)2 (5). The structures of complexes 2-5 were determined by X-ray diffraction.

  3. DFT investigation on the selective complexation of Fe3+ and Al3+ with hydroxypyridinones used for treatment of the aluminium and iron overload diseases.

    Science.gov (United States)

    Kaviani, Sadegh; Izadyar, Mohammad; Housaindokht, Mohammad Reza

    2018-03-01

    The chelating agents for Al 3+ and Fe 3+ metal cations with therapeutic applications have been considered in the recent years. In designing of the hydroxypyridinones (HPOs) as the therapeutic chelating agents for iron and aluminium overload pathologies, quantum mechanical (QM) calculations are necessary for predicting the binding energies and thermodynamic parameters of the metal-HPO complexes. Three derivatives of the HPOs called 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (DFP), 3-hydroxy-4(1H)-pyridinone (HOPO) and 5-hydroxy-2-(hydroxymethyl)pyridin-4(1H)-one (P1) were investigated for complexation with Fe 3+ and Al 3+ metal ions. Because of the maximum interaction between Fe 3+ and HPOs, all HPOs form stable complexes with Fe 3+ metal ion. Moreover, it was found that [Fe-P1] 2+ is a more stable complex than [Fe-DFP] 2+ and [Fe-3,4-HOPO] 2+ in the gas phase and water, confirming that P1 is the strongest selective iron chelator. The more stability of [Fe-P1] 2+ was attributed to an intramolecular hydrogen bond formation between the hydrogen atom of NH group and the oxygen atom of CH 2 OH chain. All complexes of the HPOs with Fe 3+ and Al 3+ were formed through the oxygen atoms of the CO and OH groups of the HPO. Natural bond orbital analysis showed that the interaction of the lone pair electrons of the oxygen atom of the chelator and antibonding orbitals of the Al 3+ and Fe 3+ are important in the complex formation. Topological parameters at the bond critical points confirmed the effective interaction between the Al 3+ and Fe 3+ metal ions and HPO as well as the nature of the metal-oxygen bonds. Copyright © 2018 Elsevier Inc. All rights reserved.

  4. The Structure of the Complex between Yeast Frataxin and Ferrochelatase: CHARACTERIZATION AND PRE-STEADY STATE REACTION OF FERROUS IRON DELIVERY AND HEME SYNTHESIS.

    Science.gov (United States)

    Söderberg, Christopher; Gillam, Mallory E; Ahlgren, Eva-Christina; Hunter, Gregory A; Gakh, Oleksandr; Isaya, Grazia; Ferreira, Gloria C; Al-Karadaghi, Salam

    2016-05-27

    Frataxin is a mitochondrial iron-binding protein involved in iron storage, detoxification, and delivery for iron sulfur-cluster assembly and heme biosynthesis. The ability of frataxin from different organisms to populate multiple oligomeric states in the presence of metal ions, e.g. Fe(2+) and Co(2+), led to the suggestion that different oligomers contribute to the functions of frataxin. Here we report on the complex between yeast frataxin and ferrochelatase, the terminal enzyme of heme biosynthesis. Protein-protein docking and cross-linking in combination with mass spectroscopic analysis and single-particle reconstruction from negatively stained electron microscopic images were used to verify the Yfh1-ferrochelatase interactions. The model of the complex indicates that at the 2:1 Fe(2+)-to-protein ratio, when Yfh1 populates a trimeric state, there are two interaction interfaces between frataxin and the ferrochelatase dimer. Each interaction site involves one ferrochelatase monomer and one frataxin trimer, with conserved polar and charged amino acids of the two proteins positioned at hydrogen-bonding distances from each other. One of the subunits of the Yfh1 trimer interacts extensively with one subunit of the ferrochelatase dimer, contributing to the stability of the complex, whereas another trimer subunit is positioned for Fe(2+) delivery. Single-turnover stopped-flow kinetics experiments demonstrate that increased rates of heme production result from monomers, dimers, and trimers, indicating that these forms are most efficient in delivering Fe(2+) to ferrochelatase and sustaining porphyrin metalation. Furthermore, they support the proposal that frataxin-mediated delivery of this potentially toxic substrate overcomes formation of reactive oxygen species. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Flavone inhibits nitric oxide synthase (NOS) activity, nitric oxide production and protein S-nitrosylation in breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wenzhen; Yang, Bingwu; Fu, Huiling; Ma, Long; Liu, Tingting; Chai, Rongfei; Zheng, Zhaodi [Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan 250014 (China); Zhang, Qunye, E-mail: wz.zhangqy@sdu.edu.cn [Key Laboratory of Cardiovascular Remodeling and Function Research Chinese Ministry of Education and Ministry of Public Health, Qilu Hospital, Shandong University, Jinan, Shandong (China); Li, Guorong, E-mail: grli@sdnu.edu.cn [Shandong Provincial Key Laboratory of Animal Resistant Biology, School of Life Sciences, Shandong Normal University, Jinan 250014 (China)

    2015-03-13

    As the core structure of flavonoids, flavone has been proved to possess anticancer effects. Flavone's growth inhibitory functions are related to NO. NO is synthesized by nitric oxide synthase (NOS), and generally increased in a variety of cancer cells. NO regulates multiple cellular responses by S-nitrosylation. In this study, we explored flavone-induced regulations on nitric oxide (NO)-related cellular processes in breast cancer cells. Our results showed that, flavone suppresses breast cancer cell proliferation and induces apoptosis. Flavone restrains NO synthesis by does-dependent inhibiting NOS enzymatic activity. The decrease of NO generation was detected by fluorescence microscopy and flow cytometry. Flavone-induced inhibitory effect on NOS activity is dependent on intact cell structure. For the NO-induced protein modification, flavone treatment significantly down-regulated protein S-nitrosylation, which was detected by “Biotin-switch” method. The present study provides a novel, NO-related mechanism for the anticancer function of flavone. - Highlights: • Flavone inhibits proliferation and induces apoptosis in MCF-7 cells. • Flavone decreases nitric oxide production by inhibiting NOS enzymatic activity in breast cancer cells. • Flavone down-regulates protein S-nitrosylation.

  6. Coupling of Carbon Dioxide with Epoxides Efficiently Catalyzed by Thioether-Triphenolate Bimetallic Iron(III) Complexes: Catalyst Structure-Reactivity Relationship and Mechanistic DFT Study

    KAUST Repository

    Della Monica, Francesco

    2016-08-25

    A series of dinuclear iron(III)I complexes supported by thioether-triphenolate ligands have been prepared to attain highly Lewis acidic catalysts. In combination with tetrabutylammonium bromide (TBAB) they are highly active catalysts in the synthesis of cyclic organic carbonates through the coupling of carbon dioxide to epoxides with the highest initial turnover frequencies reported to date for the conversion of propylene oxide to propylene carbonate for iron-based catalysts (5200h-1; 120°C, 2MPa, 1h). In particular, these complexes are shown to be highly selective catalysts for the coupling of carbon dioxide to internal oxiranes affording the corresponding cyclic carbonates in good yield and with retention of the initial stereochemical configuration. A density functional theory (DFT) investigation provides a rational for the relative high activity found for these Fe(III) complexes, showing the fundamental role of the hemilabile sulfur atom in the ligand skeleton to promote reactivity. Notably, in spite of the dinuclear nature of the catalyst precursor only one metal center is involved in the catalytic cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Thio-Pybox and Thio-Phebox complexes of chromium, iron, cobalt and nickel and their application in ethylene and butadiene polymerisation catalysis.

    Science.gov (United States)

    Nobbs, James D; Tomov, Atanas K; Cariou, Renan; Gibson, Vernon C; White, Andrew J P; Britovsek, George J P

    2012-05-21

    A series of bis(thiazolinyl)- and bis(thiazolyl)pyridine Thio-Pybox ligands and their metal complexes of chromium(III), iron(II), cobalt(II) and nickel(II) has been prepared, as well as a nickel(II) complex containing a monoanionic bis(thiazolinyl)phenyl Thio-Phebox ligand. These new metal complexes have been characterised and used as catalysts, in combination with the co-catalyst MAO, for the polymerisation of ethylene and for the polymerisation of butadiene. In the case of ethylene polymerisation, the Thio-Pybox and Thio-Phebox metal complexes have shown relatively low polymerisation activities, much lower compared to the related bis(imino)pyridine complexes of the same metals. In the polymerisation of butadiene, several Thio-Pybox cobalt(II) complexes show very high activities, significantly higher than the other metal complexes with the same ligand. It is the metal, rather than the ligand, that appears to have the most profound effect on the catalytic activity in butadiene polymerisation, unlike in the polymerisation of ethylene, where bis(imino)pyridine ligands provide highly active catalysts for a range of 1st row transition metals.

  8. Thiolate-bridged dinuclear ruthenium and iron complexes as robust and efficient catalysts toward oxidation of molecular dihydrogen in protic solvents.

    Science.gov (United States)

    Yuki, Masahiro; Sakata, Ken; Hirao, Yoshifumi; Nonoyama, Nobuaki; Nakajima, Kazunari; Nishibayashi, Yoshiaki

    2015-04-01

    Thiolate-bridged dinuclear ruthenium and iron complexes are found to work as efficient catalysts toward oxidation of molecular dihydrogen in protic solvents such as water and methanol under ambient reaction conditions. Heterolytic cleavage of the coordinated molecular dihydrogen at the dinuclear complexes and the sequential oxidation of the produced hydride complexes are involved as key steps to promote the present catalytic reaction. The catalytic activity of the dinuclear complexes toward the chemical oxidation of molecular dihydrogen achieves up to 10000 TON (turnover number), and electrooxidation of molecular dihydrogen proceeds quite rapidly. The result of the density functional theory (DFT) calculation on the reaction pathway indicates that a synergistic effect between the two ruthenium atoms plays an important role to realize the catalytic oxidation of molecular dihydrogen efficiently. The present dinuclear ruthenium complex is found to work as an efficient organometallic anode catalyst for the fuel cell. It is noteworthy that the present dinuclear complex worked not only as an effective catalyst toward chemical and electrochemical oxidation of molecular dihydrogen but also as a good anode catalyst for the fuel cell. We consider that the result described in this paper provides useful and valuable information to develop highly efficient and low-cost transition metal complexes as anode catalysts in the fuel cell.

  9. phenanthroline complex

    Indian Academy of Sciences (India)

    ABHRANIL DE

    2018-02-28

    Feb 28, 2018 ... complex in a unique binding motif and provide additional stability to the compound in the solid state. This iron(II) complex is able to catalyze the cleavage of aromatic C-C linkage of 2,5-dihydroxybenzoic acid (Gentisic acid,. GA) in oxygen environment. The iron(II) complex in the presence of two equivalent ...

  10. Iron L2,3-Edge X-ray Absorption and X-ray Magnetic Circular Dichroism Studies of Molecular Iron Complexes with Relevance to the FeMoco and FeVco Active Sites of Nitrogenase

    Science.gov (United States)

    2017-01-01

    Herein, a systematic study of a series of molecular iron model complexes has been carried out using Fe L2,3-edge X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopies. This series spans iron complexes of increasing complexity, starting from ferric and ferrous tetrachlorides ([FeCl4]−/2–), to ferric and ferrous tetrathiolates ([Fe(SR)4]−/2–), to diferric and mixed-valent iron–sulfur complexes [Fe2S2R4]2–/3–. This test set of compounds is used to evaluate the sensitivity of both Fe L2,3-edge XAS and XMCD spectroscopy to oxidation state and ligation changes. It is demonstrated that the energy shift and intensity of the L2,3-edge XAS spectra depends on both the oxidation state and covalency of the system; however, the quantitative information that can be extracted from these data is limited. On the other hand, analysis of the Fe XMCD shows distinct changes in the intensity at both L3 and L2 edges, depending on the oxidation state of the system. It is also demonstrated that the XMCD intensity is modulated by the covalency of the system. For mononuclear systems, the experimental data are correlated with atomic multiplet calculations in order to provide insights into the experimental observations. Finally, XMCD is applied to the tetranuclear heterometal–iron–sulfur clusters [MFe3S4]3+/2+ (M = Mo, V), which serve as structural analogues of the FeMoco and FeVco active sites of nitrogenase. It is demonstrated that the XMCD data can be utilized to obtain information on the oxidation state distribution in complex clusters that is not readily accessible for the Fe L2,3-edge XAS data alone. The advantages of XMCD relative to standard K-edge and L2,3-edge XAS are highlighted. This study provides an important foundation for future XMCD studies on complex (bio)inorganic systems. PMID:28653855

  11. Synthesis and Ligand Non-Innocence of Thiolate-Ligated (N4S) Iron(II) and Nickel(II) Bis(imino)pyridine Complexes

    Science.gov (United States)

    Widger, Leland R.; Jiang, Yunbo; Siegler, Maxime; Kumar, Devesh; Latifi, Reza; de Visser, Sam P.; Jameson, Guy N.L.; Goldberg, David P.

    2013-01-01

    The known iron(II) complex [FeII(LN3S)(OTf)] (1) was used as starting material to prepare the new biomimetic (N4S(thiolate)) iron(II) complexes [FeII(LN3S)(py)](OTf) (2) and [FeII(LN3S)(DMAP)](OTf) (3), where LN3S is a tetradentate bis(imino)pyridine (BIP) derivative with a covalently tethered phenylthiolate donor. These complexes were characterized by X-ray crystallography, UV-vis, 1H NMR, and Mössbauer spectroscopy, as well as electrochemistry. A nickel(II) analogue, [NiII(LN3S)](BF4) (5), was also synthesized and characterized by structural and spectroscopic methods. Cyclic voltammetric studies showed 1 – 3 and 5 undergo a single reduction process with E1/2 between −0.9 to −1.2 V versus Fc+/Fc. Treatment of 3 with 0.5% Na/Hg amalgam gave the mono-reduced complex [Fe(LN3S)(DMAP)]0 (4), which was characterized by X-ray crystallography, UV-vis, EPR (g = [2.155, 2.057, 2.038]) and Mössbauer (δ = 0.33 mm s−1; ΔEQ = 2.04 mm s−1) spectroscopies. Computational methods (DFT) were employed to model complexes 3 – 5. The combined experimental and computational studies show that 1 – 3 are 5-coordinate, high-spin (S = 2) FeII complexes, whereas 4 is best described as a 5-coordinate, intermediate-spin (S = 1) FeII complex antiferromagnetically coupled to a ligand radical. This unique electronic configuration leads to an overall doublet spin (Stotal = ½) ground state. Complexes 2 and 3 are shown to react with O2 to give S-oxygenated products, as previously reported for 1. In contrast, the mono-reduced 4 appears to react with O2 to give a mixture of S- and Fe-oxygenates. The nickel(II) complex 5 does not react with O2, and even when the mono-reduced nickel complex is produced, it appears to undergo only outer-sphere oxidation with O2. PMID:23992096

  12. Quinolinic Acid - Iron(II) Complexes: Slow Autoxidation, but Enhanced Hydroxyl Radical Production in the Fenton Reaction

    Czech Academy of Sciences Publication Activity Database

    Pláteník, J.; Stopka, Pavel; Vejražka, M.; Štípek, S.

    2001-01-01

    Roč. 34, č. 5 (2001), s. 445-459 ISSN 1071-5762 R&D Projects: GA ČR GA203/97/0642; GA ČR GA309/99/0211 Institutional research plan: CEZ:AV0Z4032918 Keywords : iron chelator * reactive oxygen species * excitotoxicity Subject RIV: CA - Inorganic Chemistry Impact factor: 2.735, year: 2001

  13. eNOS S-nitrosylates β-actin on Cys374 and regulates PKC-θ at the immune synapse by impairing actin binding to profilin-1.

    Directory of Open Access Journals (Sweden)

    Almudena García-Ortiz

    2017-04-01

    Full Text Available The actin cytoskeleton coordinates the organization of signaling microclusters at the immune synapse (IS; however, the mechanisms involved remain poorly understood. We show here that nitric oxide (NO generated by endothelial nitric oxide synthase (eNOS controls the coalescence of protein kinase C-θ (PKC-θ at the central supramolecular activation cluster (c-SMAC of the IS. eNOS translocated with the Golgi to the IS and partially colocalized with F-actin around the c-SMAC. This resulted in reduced actin polymerization and centripetal retrograde flow of β-actin and PKC-θ from the lamellipodium-like distal (d-SMAC, promoting PKC-θ activation. Furthermore, eNOS-derived NO S-nitrosylated β-actin on Cys374 and impaired actin binding to profilin-1 (PFN1, as confirmed with the transnitrosylating agent S-nitroso-L-cysteine (Cys-NO. The importance of NO and the formation of PFN1-actin complexes on the regulation of PKC-θ was corroborated by overexpression of PFN1- and actin-binding defective mutants of β-actin (C374S and PFN1 (H119E, respectively, which reduced the coalescence of PKC-θ at the c-SMAC. These findings unveil a novel NO-dependent mechanism by which the actin cytoskeleton controls the organization and activation of signaling microclusters at the IS.

  14. S -Nitrosylation inhibits the kinase activity of tomato phosphoinositide-dependent kinase 1 (PDK1)

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian-Zhong; Duan, Jicheng; Ni, Min; Liu, Zhen; Qiu, Wen-Li; Whitham, Steven A.; Qian, Wei-Jun

    2017-09-29

    It is well known that the reactive oxygen species, nitric oxide (NO), can trigger cell death in plants, but the underlying molecular mechanisms are not well understood. Here, we provide evidence that NO may trigger cell death in tomato (Solanum lycopersicon) through inhibiting the phosphoinositide-dependent kinase 1 (PDK1) kinase activity via S-nitrosylation. Biotin-switch assays and LC-MS/MS analyses demonstrated that SlPDK1 was a target of S-nitrosylation modification, which primarily occurred on the cysteine residue at position 128 (Cys128). Accordingly, the kinase activity of SlPDK1 was inhibited by S-nitrosoglutathione (GSNO) both in vitro and in vivo in a concentration-dependent manner, indicating that SlPDK1 activity is regulated by S-nitrosylation. The inhibition of SlPDK1 kinase activity by GSNO was reversible in the presence of a reducing agent but synergistically enhanced by hydrogen peroxide (H2O2). Mutation of Cys128 to serine completely abolished SlPDK1 kinase activity, suggesting that S-nitrosylation of Cys128 is responsible for the inhibition of the kinase activity of SlPDK1. In sum, our results established a potential link between NO-triggered cell death and inhibition of the kinase activity of tomato PDK1, a conserved negative regulator of cell death in yeasts, mammals and plants. Nitric oxide (NO) potentiates the induction of hypersensitive cell death in soybean cells by reactive oxygen species (ROS) (1). However, the molecular mechanism of the NO-induced cell death remains an enigma. One potential mechanism is that the activity of proteins that control cell death may be altered by a post-translational modification, S-nitrosylation. S-nitrosylation is the addition of the NO moiety to thiol groups, including cysteine (Cys) residues in proteins, to form S-nitrosothiols (SNOs). S-nitrosylation is an enzyme-independent post-translational and labile modification that can function as an on/off switch of protein activity (2- 4). Thousands of diverse

  15. The mechanism of stereospecific C-H oxidation by Fe(Pytacn) complexes: bioinspired non-heme iron catalysts containing cis-labile exchangeable sites.

    Science.gov (United States)

    Prat, Irene; Company, Anna; Postils, Verònica; Ribas, Xavi; Que, Lawrence; Luis, Josep M; Costas, Miquel

    2013-05-17

    A detailed mechanistic study of the hydroxylation of alkane C-H bonds using H2O2 by a family of mononuclear non heme iron catalysts with the formula [Fe(II)(CF3SO3)2(L)] is described, in which L is a tetradentate ligand containing a triazacyclononane tripod and a pyridine ring bearing different substituents at the α and γ positions, which tune the electronic or steric properties of the corresponding iron complexes. Two inequivalent cis-labile exchangeable sites, occupied by triflate ions, complete the octahedral iron coordination sphere. The C-H hydroxylation mediated by this family of complexes takes place with retention of configuration. Oxygen atoms from water are incorporated into hydroxylated products and the extent of this incorporation depends in a systematic manner on the nature of the catalyst, and the substrate. Mechanistic probes and isotopic analyses, in combination with detailed density functional theory (DFT) calculations, provide strong evidence that C-H hydroxylation is performed by highly electrophilic [Fe(V)(O)(OH)L] species through a concerted asynchronous mechanism, involving homolytic breakage of the C-H bond, followed by rebound of the hydroxyl ligand. The [Fe(V)(O)(OH)L] species can exist in two tautomeric forms, differing in the position of oxo and hydroxide ligands. Isotopic-labeling analysis shows that the relative reactivities of the two tautomeric forms are sensitively affected by the α substituent of the pyridine, and this reactivity behavior is rationalized by computational methods. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. The Pharmacokinetics and Pharmacodynamics of Iron Preparations

    Directory of Open Access Journals (Sweden)

    Susanna Burckhardt

    2011-01-01

    Full Text Available Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3−4 weeks. Accordingly, serum iron concentration and area under the curve (AUC are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III-hydroxide complexes with carbohydrate ligands or orally as iron(II (ferrous salts or iron(III (ferric complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.

  17. Nitric Oxide Synthase 1 Modulates Basal and β-Adrenergic-Stimulated Contractility by Rapid and Reversible Redox-Dependent S-Nitrosylation of the Heart.

    Directory of Open Access Journals (Sweden)

    Alejandra Z Vielma

    Full Text Available S-nitrosylation of several Ca2+ regulating proteins in response to β-adrenergic stimulation was recently described in the heart; however the specific nitric oxide synthase (NOS isoform and signaling pathways responsible for this modification have not been elucidated. NOS-1 activity increases inotropism, therefore, we tested whether β-adrenergic stimulation induces NOS-1-dependent S-nitrosylation of total proteins, the ryanodine receptor (RyR2, SERCA2 and the L-Type Ca2+ channel (LTCC. In the isolated rat heart, isoproterenol (10 nM, 3-min increased S-nitrosylation of total cardiac proteins (+46±14% and RyR2 (+146±77%, without affecting S-nitrosylation of SERCA2 and LTCC. Selective NOS-1 blockade with S-methyl-L-thiocitrulline (SMTC and Nω-propyl-l-arginine decreased basal contractility and relaxation (-25-30% and basal S-nitrosylation of total proteins (-25-60%, RyR2, SERCA2 and LTCC (-60-75%. NOS-1 inhibition reduced (-25-40% the inotropic response and protein S-nitrosylation induced by isoproterenol, particularly that of RyR2 (-85±7%. Tempol, a superoxide scavenger, mimicked the effects of NOS-1 inhibition on inotropism and protein S-nitrosylation; whereas selective NOS-3 inhibitor L-N5-(1-Iminoethylornithine had no effect. Inhibition of NOS-1 did not affect phospholamban phosphorylation, but reduced its oligomerization. Attenuation of contractility was abolished by PKA blockade and unaffected by guanylate cyclase inhibition. Additionally, in isolated mouse cardiomyocytes, NOS-1 inhibition or removal reduced the Ca2+-transient amplitude and sarcomere shortening induced by isoproterenol or by direct PKA activation. We conclude that 1 normal cardiac performance requires basal NOS-1 activity and S-nitrosylation of the calcium-cycling machinery; 2 β-adrenergic stimulation induces rapid and reversible NOS-1 dependent, PKA and ROS-dependent, S-nitrosylation of RyR2 and other proteins, accounting for about one third of its inotropic effect.

  18. Uptake of iron (III)-ethylenediamine-N, N, N', N'-tetraacetic acid complex by phosphatidylcholine lipid film. Part II. Effect of film curvature.

    Science.gov (United States)

    Villeneuve, Masumi; Tanaka, Mihoko; Saito, Natsumi; Sakamoto, Hiroyasu; Hayami, Yoshiteru

    2018-01-01

    Mixed micelles formed in a ternary-solute aqueous solution of NaOH, iron (III)-ethylenediamine-N, N, N', N'-tetraacetic acid complex (Fe-EDTA) and 1,2-diheptanoyl-sn-glycero-3-phosphatidyl choline (DHPC) were studied and compared with the mixed adsorbed film reported in Part I of this series to clarify the effect of the curvature of molecular assemblies on the interactions between their Fe-EDTA and DHPC constituents. The critical micelle concentrations (CMCs), surface tension at the CMC, and solution pH were measured as functions of the mole fractions of NaOH and DHPC. Rigorous thermodynamic equations were derived, in which the overall proton dissociation equilibria of Fe-EDTA and DHPC were taken into consideration, and applied to experimental data to obtain phase diagrams of micelle formation and the micelle-adsorbed film equilibrium. It was found that when the bulk solution was strongly acidic, Fe-EDTA was incorporated in the micelles. However, the adsorbed film was more Fe-EDTA-enriched than the micelle. These findings imply that a flat cell membrane is more permeable to an iron complex than a cell membrane with positive curvature. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Cytotoxicity study of iron oxide nanoparticles, single-wall carbon nanotubes and their complexes applied to MCF7 breast cancer cells

    Science.gov (United States)

    Mege, Karine

    Reactive Oxygen Species (ROS) are radicals of great concern to biologists. Their role in several diseases---such as neurodegenerative disease, diabetes, premature aging and cancer---has been intensively investigated during the last decade. Since a major focus in cancer research is to better understand how it is induced and therefore how it can be cured, the study of the cytotoxic effects of ROS production within cancer cells is vital. Nanotechnology is an emerging field of science that promises great improvements in a number of disciplines. Nano medicine is one of its daughter fields. Various nanomaterials are used for diagnosis and disease detection, therapy and medical imaging, and many are already being used in oncology medicine. The two most frequently used nanomaterials in cancer research are Carbon nanotubes (CNTs) and iron oxide nanoparticles (IONPs). They have been proven to play a significant role in the ROS production of various cancer cells. In this context, this thesis emphasizes the need to study the impact of nanoparticles, such as single-walled carbon nanotubes (SWCNTs), iron oxide nanoparticles (IONPs) and their complexes, on a human breast cancer cell line (MCF-7). To date, there have been very few studies assessing the effect on the oxidative stress activity of this cell line using these nanoparticles and their complexes.

  20. Moessbauer spectroscopic study on valence-detrapping and trapping of mixed-valence trinuclear iron (III, III, II) fluorine-substitute benzoate complexes

    International Nuclear Information System (INIS)

    Sakai, Y.; Onaka, S.; Ogiso, R.; Takayama, T.; Takahashi, M.; Nakamoto, T.

    2012-01-01

    Four mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes were synthesized; Fe 3 O(C 6 F 5 COO) 6 (C 5 H 5 N) 3 ·CH 2 Cl 2 (1), Fe 3 O(C 6 F 5 COO) 6 (C 5 H 5 N) 3 (2), Fe 3 O(2H-C 6 F 4 COO) 6 (C 5 H 5 N) 3 (3), and Fe 3 O(4H-C 6 F 4 COO) 6 (C 5 H 5 N) 3 (4). By means of 57 Fe-Moessbauer spectroscopy, valence-detrapping and trapping phenomena have been investigated for the four mixed-valence complexes. The valence state of three iron ions is trapped at lower temperatures while it is fully detrapped at higher temperatures for 1. Valence detrapping is not observed for 2, 3, and 4 even at room temperature, although Moessbauer spectra for 3 and 4 show a complicated temperature dependence. (author)

  1. Synthesis, characterization and single crystal x-ray analysis of a complex of iron(II) bis(2,4-dimethylphenyl)dithiophosphate with 4-ethylpyridine

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sandeep; Andotra, Savit; Kaur, Mandeep [University of Jammu, Department of Chemistry (India); Gupta, Vivek K.; Kant, Rajni [Department of Physics and Electronics, University of Jammu, X-ray Crystallographic Laboratory (India); Pandey, Sushil K., E-mail: kpsushil@rediffmail.com [University of Jammu, Department of Chemistry (India)

    2016-09-15

    Complex of iron(II) bis(2,4-dimethylphenyl)dithiophosphate with 4-ethylpyridine [((2,4- (CH{sub 3}){sub 2}C{sub 6}H{sub 3}O)2PS2)2Fe(NC{sub 5}H{sub 4}(C{sub 2}H{sub 5})-4){sub 2}] is synthesized and characterized by elemental analysis, magnetic moment, IR spectroscopy and single crystal X-ray analysis. Complex crystallizes in the monoclinic sp. gr. P2{sub 1}/n, Z = 2. Crystal structure consists of mononuclear units with Fe(II) ion chelated by four S atoms of the two diphenyldithiophosphate ligands in bidentate manner. N atoms from two 4-ethylpyridine ligands are axially coordinated to the Fe(II) atom leading to an octahedral geometry.

  2. Preparation and characterization of uranium-iron triple-bonded UFe(CO){sub 3}{sup -} and OUFe(CO){sub 3}{sup -} complexes

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Chaoxian; Meng, Luyan; Luo, Mingbiao [School of Chemistry, Biological and Materials Sciences, State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China University of Technology, Nanchang (China); Wang, Jia-Qi; Li, Wan-Lu; Li, Jun [Department of Chemistry and Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Tsinghua University, Beijing (China); Qu, Hui; Zhou, Mingfei [Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai (China)

    2017-06-06

    We report the preparation of UFe(CO){sub 3}{sup -} and OUFe(CO){sub 3}{sup -} complexes using a laser-vaporization supersonic ion source in the gas phase. These compounds were mass-selected and characterized by infrared photodissociation spectroscopy and state-of-the-art quantum chemical studies. There are unprecedented triple bonds between U 6d/5f and Fe 3d orbitals, featuring one covalent σ bond and two Fe-to-U dative π bonds in both complexes. The uranium and iron elements are found to exist in unique formal U(I or III) and Fe(-II) oxidation states, respectively. These findings suggest that there may exist a whole family of stable df-d multiple-bonded f-element-transition-metal compounds that have not been fully recognized to date. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Synthesis and characterization of μ-hydroxido- and μ-polycarboxylato-bridged iron(III complexes with 2,2’-bipyridine

    Directory of Open Access Journals (Sweden)

    Tasić Nikola

    2014-01-01

    Full Text Available Four novel polymeric iron(III complexes with 2,2’-bipyridine (bipy and different aromatic polycarboxylato ligands as anions of phthalic (pht, isophthalic (ipht, terephthalic (tpht and pyromellitic (pyr acid were synthesized by ligand exchange reaction. The complexes were characterized by elemental and TG/DSC analysis, FTIR and diffuse reflectance UV-VIS-NIR spectroscopy and magnetic susceptibility measurements. Based on analytical and spectral data the formulae of the complexes are {[Fe4(bipy2 (H2O2(OH6(pht3]•2H2O}n (1, {[Fe4(bipy2(Hipht2(ipht2(OH6]•4H2O}n (2, {[Fe4(bipy2(Htpht2(OH6(tpht2]•4H2O}n (3 and {[Fe4(bipy(H2O8(OH4 (pyr2]•H2O}n (4. All complexes are red brown and low-spin with a distorted octahedral geometry and FeO6 or FeN2O4 chromophore. Polycarboxylato ligands have a bridging role in all cases, whereas monodentate COO groups are present in 2 and 3, bridging and chelate COO groups are established in 1 and 4. The thermal behaviour of 1-4 was investigated in detail and the molar dehydration enthalpies were calculated. According to the all those results, the structural formulae of the complexes 1-4 were proposed. [Projekat Ministarstva nauke Republike Srbije, br. III45007

  4. Direct and indirect photodegradation of estriol in the presence of humic acid, nitrate and iron complexes in water solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yong [Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA 02747 (United States); School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, Kai [Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA 02747 (United States); Zuo, Yuegang, E-mail: yzuo@umassd.edu [Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA 02747 (United States)

    2013-10-01

    The photochemical behavior of a natural estrogen estriol (E3) was investigated in the presence of the natural photoreactive constituents including nitrate, iron(III), and humic acid (HA). The direct photodegradation of E3 increased with increasing incident light intensity, decreasing initial concentration of E3 and increasing pH in the range of 6.0 to 10.0. The direct photodegradation of the deprotonated speciation of E3 was much faster than that of its protonated form. The presence of NO{sub 3}{sup −} and iron(III) promoted the photochemical loss of E3 in the aqueous solutions. The quenching experiments verified that hydroxyl radicals were predominantly responsible for the indirect photodegradation of E3. HA could act as photosensitizer, light screening agent and free radical quencher. For the first time, the enhancement or inhibition effect of HA on photodegradation was found to depend on the irradiation light intensity. HA enhanced the photodegradation of E3 under sunlight or weak irradiation of simulated sunlight. In contrast, under high irradiation light intensity, HA inhibited the photodegradation. The hydroxylation photoproducts were identified using GC-MS and the photodegradation pathway of E3 was proposed. - Highlights: • Direct and indirect photodegradation of estriol (E3) were first investigated. • The direct photodegradation of E3 increased with increasing pH of the solutions. • The light intensity affected the photosensitization effect of humic acid. • Nitrate and iron(III) promoted the photodecomposition of estriol in water. • The ·OH oxidation products of E3 was first determined.

  5. Unsymmetrical Chelation of N-Thioether-Functionalized Bis(diphenylphosphino)amine-Type Ligands and Substituent Effects on the Nuclearity of Iron(II) Complexes: Structures, Magnetism, and Bonding.

    Science.gov (United States)

    Fliedel, Christophe; Rosa, Vitor; Falceto, Andrés; Rosa, Patrick; Alvarez, Santiago; Braunstein, Pierre

    2015-07-06

    Starting from the short-bite ligands N-thioether-functionalized bis(diphenylphosphino)amine-type (Ph2P)2N(CH2)3SMe (1) and (Ph2P)2N(p-C6H4)SMe (2), the Fe(II) complexes [FeCl2(1)]n (3), [FeCl2(2)]2 (4), [Fe(OAc)(1)2]PF6 (5), and [Fe(OAc)(2)2]PF6 (6) were synthesized and characterized by Fourier transform IR, mass spectrometry, elemental analysis, and also by X-ray diffraction for 3, 4, and 6. Complex 3 is a coordination polymer in which 1 acts as a P,P-pseudochelate and a (P,P),S-bridge, whereas 4 has a chlorido-bridged dinuclear structure in which 2 acts only as a P,P-pseudochelate. Since these complexes were obtained under strictly similar synthetic and crystallization conditions, these unexpected differences were ascribed to the different spacer between the nitrogen atom and the −SMe group. In both compounds, one Fe–P bond was found to be unusually long, and a theoretical analysis was performed to unravel the electronic or steric reasons for this difference. Density functional theory calculations were performed for a set of complexes of general formula [FeCl2(SR2){R21PN(R2)P′R23}] (R = H, Me; R1, R2, and R3 = H, Me, Ph), to understand the reasons for the significant deviation of the iron coordination sphere away from tetrahedral as well as from trigonal bipyramidal and the varying degree of unsymmetry of the two Fe–P bonds involving pseudochelating PN(R)P ligands. Electronic factors nicely explain the observed structures, and steric reasons were further ruled out by the structural analysis in the solid-state of the bis-chelated complex 6, which displays usual and equivalent Fe–P bond lengths. Magnetic susceptibility studies were performed to examine how the structural differences between 3 and 4 would affect the interactions between the iron centers, and it was concluded that 3 behaves as an isolated high-spin Fe(II) mononuclear complex, while significant intra- and intermolecular ferromagnetic interactions were evidenced for 4 at low temperatures

  6. Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M114: evidence for the involvement of iron, the ECF sigma factor, PbrA and pseudobactin M114 siderophore.

    Science.gov (United States)

    Maunsell, Bláithín; Adams, Claire; O'Gara, Fergal

    2006-01-01

    In the soil bacterium Pseudomonas fluorescens M114, extracellular proteolytic activity and fluorescent siderophore (pseudobactin M114) production were previously shown to be co-ordinately negatively regulated in response to environmental iron levels. An iron-starvation extracytoplasmic function sigma factor, PbrA, required for the transcription of siderophore biosynthetic genes, was also implicated in M114 protease regulation. The current study centred on the characterization and genetic regulation of the gene(s) responsible for protease production in M114. A serralysin-type metalloprotease gene, aprA, was identified and found to encode the major, if not only, extracellular protease produced by this strain. The expression of aprA and its protein product were found to be subject to complex regulation. Transcription analysis confirmed that PbrA was required for full aprA transcription under low iron conditions, while the ferric uptake regulator, Fur, was implicated in aprA repression under high iron conditions. Interestingly, the iron regulation of AprA was dependent on culture conditions, with PbrA-independent AprA-mediated proteolytic activity observed on skim milk agar supplemented with yeast extract, when supplied with iron or purified pseudobactin M114. These effects were not observed on skim milk agar without yeast extract. PbrA-independent aprA expression was also observed from a truncated transcriptional fusion when grown in sucrose asparagine tryptone broth supplied with iron or purified pseudobactin M114. Thus, experimental evidence suggested that iron mediated its effects via transcriptional activation by PbrA under low iron conditions, while an as-yet-unidentified sigma factor(s) may be required for the PbrA-independent aprA expression and AprA proteolytic activity induced by siderophore and iron.

  7. Synthesis and reactivity of iron complexes with a new pyrazine-based pincer ligand, and application in catalytic low-pressure hydrogenation of carbon dioxide.

    Science.gov (United States)

    Rivada-Wheelaghan, Orestes; Dauth, Alexander; Leitus, Gregory; Diskin-Posner, Yael; Milstein, David

    2015-05-04

    A novel pincer ligand based on the pyrazine backbone (PNzP) has been synthesized, (2,6-bis(di(tert-butyl)phosphinomethyl)pyrazine), tBu-PNzP. It reacts with FeBr2 to yield [Fe(Br)2(tBu-PNzP)], 1. Treatment of 1 with NaBH4 in MeCN/MeOH gives the hydride complex [Fe(H)(MeCN)2(tBu-PNzP)][X] (X = Br, BH4), 2·X. Counterion exchange and exposure to CO atmosphere yields the complex cis-[Fe(H)(CO)(MeCN)(tBu-PNzP)][BPh4] 4·BPh4, which upon addition of Bu4NCl forms [Fe(H)(Cl)(CO)(tBu-PNzP)] 5. Complex 5, under basic conditions, catalyzes the hydrogenation of CO2 to formate salts at low H2 pressure. Treatment of complex 5 with a base leads to aggregates, presumably of dearomatized species B, stabilized by bridging to another metal center by coordination of the nitrogen at the backbone of the pyrazine pincer ligand. Upon dissolution of compound B in EtOH the crystallographically characterized complex 7 is formed, comprised of six iron units forming a 6-membered ring. The dearomatized species can activate CO2 and H2 by metal-ligand cooperation (MLC), leading to complex 8, trans-[Fe(PNzPtBu-COO)(H)(CO)], and complex 9, trans-[Fe(H)2(CO)(tBu-PNzP)], respectively. Our results point at a very likely mechanism for CO2 hydrogenation involving MLC.

  8. Methotrexate administration induces differential and selective protein tyrosine nitration and cysteine nitrosylation in the subcellular organelles of the small intestinal mucosa of rats.

    Science.gov (United States)

    Natarajan, Kasthuri; Abraham, Premila

    2016-05-05

    Gastrointestinal toxicity is one of the most frequent dose limiting side effects of methotrexate (MTX), a commonly used chemotherapeutic drug. Peroxynitrite (PON) overproduction is reported to contribute to MTX induced gastrointestinal mucositis. However, the consequence of PON overproduction i.e. protein tyrosine nitration and protein cysteine nitrosylation, the subcellular distribution of these modified proteins and their molecular weights have not been investigated yet. Mucositis was induced in Wistar rats by the administration of 3 consecutive i.p. injections of MTX. Tyrosine nitrated proteins and cysteine nitrosylated proteins were determined in the subcellular organelles fractions of mucosa using immunoprecipitation and western blot. The proteins in the subcellular fractions were separated by 1D electrophoresis, and probed with anti -nitrotyrosine antibody and anti-nitrosocysteine antibody. After MTX treatment, a general increase in protein tyrosine nitration as well as a change in the spectrum of proteins that underwent nitration was observed. The relative densities of the 3 nitrotyrosine protein adducts were as follows: Mitochondria > cytosol > microsomes > nucleus. In the mitochondrial fraction increased nitration of 12 kDa, 25 kDa 29Kda, 47 kDa, and 62Kda proteins, in the cytosol increased nitration of 12 kDa, 19 kDa, 45 kDa, and 60 kDa proteins and in the nuclear fraction increased nitration of 17 kDa, 35 kDa, and 58 kDa proteins was observed. On the other hand, MTX treatment resulted to a general decrease in protein cysteine nitrosylation in all the subcellular fractions. These results suggest that MTX induced, PON mediated small intestinal injury is mediated by differential nitration and nitrosylation of proteins in the subcellular organelles with increased protein tyrosine nitration and decreased cysteine nitrosylation. In addition MTX treatment results in selective nitration and nitrosylation of proteins in the intestinal mucosa. This differential

  9. The antitumor mechanism of di-2-pyridylketone 2-pyridine carboxylic acid hydrazone and its copper complex in ROS generation and topoisomerase inhibition, and hydrazone involvement in oxygen-catalytic iron mobilization.

    Science.gov (United States)

    Huang, Tengfei; Li, Cuiping; Sun, Xingzhi; Zhu, Zhenfu; Fu, Yun; Liu, Youxun; Yuan, Yanbin; Li, Shaoshan; Li, Changzheng

    2015-11-01

    Iron depletion and stimulation of iron-dependent free radical damage is a rapidly developing field for chelation therapy, but the iron mobilization from ferritin by chelators has received less attention. In this study, the di-2-pyridylketone 2-pyridine carboxylic acid hydrazone (DPPCAH) and its copper complex was prepared and characterized by NMR and MS spectra. The proliferation inhibition assay showed that both DPPCAH and its copper complex exhibited selectively proliferation inhibition for HepG2 (IC50, 4.6 ± 0.2 µM for DPPACH and 1.3 ± 0.2 µM for its copper complex), but less inhibition for HCT-116 cell line (IC50, >100 µM for DPPACH and 7.8 ± 0.4 µM for its copper complex). The mechanistic studies revealed that DPPACH could remove iron from ferritin in a oxygen-catalytic manner, and contributed to redox activity of labile iron pool (LIP), that is less reported for the chelators that possess significant biological activity. The reactive oxygen species (ROS) generation and DNA cleavage assay in vitro and in vivo showed that both DPPACH-Fe(II) and DPPACH-Cu were redox-active species, indicating that ROS may mediate their antitumor activity. Further study revealed that both DPPACH and its copper complex displayed certain degree of inhibition of type II topoisomerase (Top) which contributed to their antitumor activity. Thus, the mechanism that iron mobilization by DPPACH from ferritin contributed to LIP was proposed, and both DPPACH and its copper complex were involved in ROS generation and Top II inhibition for their antitumor activities.

  10. Oral iron administration in suckling piglets – a review

    Directory of Open Access Journals (Sweden)

    Martin Svoboda

    2018-01-01

    Full Text Available Iron deficiency is presently a serious problem in suckling piglets on pig farms. The most often used method of anaemia prevention in piglets is parenteral administration of iron dextran. Oral iron represents an alternative to this method. The goal of this article is to review current knowledge on oral iron administration in suckling piglets. The substances that can be used for this purpose include iron dextran, iron salts, iron chelates, carbonyl iron, an iron polymaltose complex and iron microparticles. The different methods of oral iron administration in piglets are discussed.

  11. l-arginine ingestion inhibits eccentric contraction-induced proteolysis and force deficit via S-nitrosylation of calpain.

    Science.gov (United States)

    Kanzaki, Keita; Watanabe, Daiki; Aibara, Chihiro; Kawakami, Yuki; Yamada, Takashi; Takahashi, Yoshitaka; Wada, Masanobu

    2018-01-01

    It has been shown that calpains are involved in the proteolysis of muscle proteins that occurs with eccentric contraction (ECC) and that exogenously applied nitric oxide decreases the calpain-mediated proteolysis. The aim of this study was to examine the effects of ingestion of l-arginine (ARG), a nitric oxide precursor, on ECC-related calpain activation. In the first and second experiments, male Wistar rats were given ARG in water for 7 days starting from 3 days before the ECC protocol (average ingestion, ~600 mg kg-body wt -1  day -1 ). Tibialis anterior muscles underwent 200 repeated ECCs and, subsequently, were excised 3 days later. Whole muscle analyses (the first experiment) revealed that ARG attenuated ECC-induced force deficit and autolysis of calpain-1, and increased the amounts of S-nitrosylated calpain-1. Regarding ryanodine receptor (RyR) and dihydropyridine receptor (DHPR), ECC-induced proteolysis was completely inhibited by ARG, whereas the inhibition was partial for junctophilin-1 (JP1). Skinned fiber analyses (the second experiment) showed that ARG also inhibited ECC-elicited reductions in the ratio of depolarization-induced to maximum Ca 2+ -activated force. In the third experiment, homogenates of rested muscles were treated with S-nitrosylating agent, S-nitrosoglutathione (GSNO), and/or high Ca 2+ concentration ([Ca 2+ ]). Treatment with high [Ca 2+ ] and without GSNO produced proteolysis of RyR, DHPR, and JP1. On the other hand, treatment with high [Ca 2+ ] and GSNO caused complete inhibition of RyR and DHPR proteolysis and partial inhibition of JP1 proteolysis. These results indicate that ARG ingestion can attenuate ECC-induced proteolysis of Ca 2+ regulatory proteins and force deficit by decreasing calpain activation via S-nitrosylation. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  12. Ginsenoside Rg3 regulates S-nitrosylation of the NLRP3 inflammasome via suppression of iNOS

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sung-Jin; Park, Jun-Young [Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon (Korea, Republic of); Department of Functional Genomics, University of Science and Technology, Yuseong-gu, Daejeon (Korea, Republic of); Choi, Song [Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Jin-Bong; Jung, Haiyoung; Kim, Tae-Don; Yoon, Suk Ran; Choi, Inpyo [Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon (Korea, Republic of); Department of Functional Genomics, University of Science and Technology, Yuseong-gu, Daejeon (Korea, Republic of); Shim, Sungbo, E-mail: sungbo@ulsan.ac.kr [Department of Biomedical Sciences & Neuromarker Resource Bank (NRB), University of Ulsan College of Medicine, Seoul 138-736 (Korea, Republic of); Park, Young-Jun, E-mail: pyj71@kribb.re.kr [Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon (Korea, Republic of); Department of Functional Genomics, University of Science and Technology, Yuseong-gu, Daejeon (Korea, Republic of)

    2015-08-07

    Ginsenoside Rg3, a specific biological effector, is well-known as a major bioactive ingredient of Panax ginseng. However, its role in the inflammasome activation process remains unclear. In this report, we demonstrate that ginsenosides 20(R)-Rg3 and 20(S)-Rg3 are capable of suppressing both lethal endotoxic shock and the S-nitrosylation of the NLRP3 inflammasome by inhibiting nitric oxide (NO) production through the regulation of inducible nitric oxide synthase (iNOS) expression. In response to lipopolysaccharide (LPS), the reducing effect of 20(S)-Rg3 and 20(R)-Rg3 on nitric oxide led to an increase in the survival time of mice after lethal endotoxin-induced shock, and excess levels of NO inhibited IL-1β production via the S-nitrosylation of the NLRP3 inflammasome. In addition, ginsenosides 20(R)-Rg3 and 20(S)-Rg3 had suppressive effects on the LPS- or UV-irradiation-induced reactive oxygen species (ROS) levels in macrophage and HaCaT cells and thereby prevented apoptosis of spleen cells in mice. Altogether, these results demonstrate that ginsenoside 20(R)-Rg3 and 20(S)-Rg3, a naturally occurring compound, might act as a dual therapeutic regulator for the treatment of inflammatory and oxidative stress-related diseases. - Highlights: • Ginsenosides Rg3 inhibits NO production through the regulation of iNOS expression. • Ginsenosides Rg3 inhibits the S-nitrosylation of the NLRP3 inflammasome. • Ginsenosides Rg3 suppress on the LPS- or UV-irradiation-induced ROS levels in cells.

  13. Dilution Methods in Flow Injection Analysis. Evaluation of Different Approaches as Exemplified for the Determination of Nitrosyl in Concentrated Sulphuric Acid

    DEFF Research Database (Denmark)

    Jørgensen, Ulla Vang; Nielsen, Steffen; Hansen, Elo Harald

    1998-01-01

    in conjunction with knotted reactors of relatively large internal diameter (1.5 mm). The optimized FI-manifold was used with the Griess method for the spectrophotometric assay of nitrosyl (nitrite) in standards prepared in the matrix of concentrated sulphuric acid (detection limit 0.16 mg/l NO+-N (3s......Instigated by developing a flow injection procedure for assay of nitrosyl in concentrated sulphuric acid, different approaches for reliable and robust on-line dilution in FIA were evaluated. These comprised the application of mixing tees in conjunction with mixing coils (including knotted reactors...

  14. Electronic, Magnetic, and Redox Properties and O2Reactivity of Iron(II) and Nickel(II) o-Semiquinonate Complexes of a Tris(thioether) Ligand: Uncovering the Intradiol Cleaving Reactivity of an Iron(II) o-Semiquinonate Complex.

    Science.gov (United States)

    Wang, Peng; Killian, Michelle M; Saber, Mohamed R; Qiu, Tian; Yap, Glenn P A; Popescu, Codrina V; Rosenthal, Joel; Dunbar, Kim R; Brunold, Thomas C; Riordan, Charles G

    2017-09-05

    The iron(II) semiquinonate character within the iron(III) catecholate species has been proposed by numerous studies to account for the O 2 reactivity of intradiol catechol dioxygenases, but a well-characterized iron(II) semiquinonate species that exhibits intradiol cleaving reactivity has not yet been reported. In this study, a detailed electronic structure description of the first iron(II) o-semiquinonate complex, [PhTt tBu ]Fe(phenSQ) [PhTt tBu = phenyltris(tert-butylthiomethyl)borate; phenSQ = 9,10-phenanthrenesemiquinonate; Wang et al. Chem. Commun. 2014, 50, 5871-5873], was generated through a combination of electronic and Mössbauer spectroscopies, SQUID magnetometry, and density functional theory (DFT) calculations. [PhTt tBu ]Fe(phenSQ) reacts with O 2 to generate an intradiol cleavage product, diphenic anhydride, in 16% yield. To assess the dependence of the intradiol reactivity on the identity of the metal ion, the nickel analogue, [PhTt tBu ]Ni(phenSQ), and its derivative, [PhTt tBu ]Ni(3,5-DBSQ) (3,5-DBSQ = 3,5-di-tert-butyl-1,2-semiquinonate), were prepared and characterized by X-ray crystallography, mass spectrometry, 1 H NMR and electronic spectroscopies, and SQUID magnetometry. DFT calculations, evaluated on the basis of the experimental data, support the electronic structure descriptions of [PhTt tBu ]Ni(phenSQ) and [PhTt tBu ]Ni(3,5-DBSQ) as high-spin nickel(II) complexes with antiferromagnetically coupled semiquinonate ligands. Unlike its iron counterpart, [PhTt tBu ]Ni(phenSQ) decomposes slowly in an O 2 atmosphere to generate 14% phenanthrenequinone with a negligible amount of diphenic anhydride. [PhTt tBu ]Ni(3,5-DBSQ) does not react with O 2 . This dramatic effect of the metal-ion identity supports the hypothesis that a metal(III) alkylperoxo species serves as an intermediate in the intradiol cleaving reactions. The redox properties of all three complexes were probed using cyclic voltammetry and differential pulse voltammetry, which indicate

  15. Some complexes of cobalt(III) and iron(III) are radiosensitizers of hypoxic EMT6 cells.

    Science.gov (United States)

    Teicher, B A; Jacobs, J L; Cathcart, K N; Abrams, M J; Vollano, J F; Picker, D H

    1987-01-01

    The radiosensitizing potential in hypoxic EMT6 cells of several complexes of Co(III) and Fe(III) has been examined. The cytotoxicity of each of the agents toward oxygenated and hypoxic EMT6 cells was tested over the concentration range of 1 to 500 micron for 1-h drug exposure. There was no statistically significant difference between the cytotoxicity of these complexes toward oxygenated and hypoxic cells. Based on these findings, 100 micron was selected as the drug concentration for the initial assessment of radiosensitizing potential. The radiation survival of EMT6 cells in the presence of 100 microM drug for a series of Co(III) complexes in which the number of nitro ligands was varied showed that the hexanitro and the triamine-trinitro complexes are very effective radiosensitizers. The trans-tetrammine dinitro complex was a more effective radiosensitizer than the corresponding cis-dinitro complex. The diethylenetriamine and 1,10-phenanthroline complexes were very effective radiosensitizers, producing dose-modifying factors of 2.4. The trans-tetrammine dichloro complex was moderately effective, giving a dose-modifying factor of 1.9. On the other hand, the hexammine and triammine tricyano complexes and the trans-dinitro complex with negatively charged acetylacetonate ligands were ineffective as radiosensitizers in this system. Finally, three complexes with cyclopentadienyl ligands were examined. The ferricenium salt itself was a moderately effective radiosensitizer, giving a dose-modifying factor of 2.0. However, both the dimethylferricenium salt and the analogous cobalt complex were ineffective. The FSaIIC fibrosarcoma was used to study radiosensitizing potential in vivo. The trans-tetramminedinitro complex was administered at doses of 100, 200, or 300 mg/kg as a single ip injection 1 h prior to irradiation or as three daily ip injections. There was increasing dose modification with increasing drug dosage. With a fractionated radiation protocol in which five daily

  16. Evaluation and economics aspects of the lying of rare earth and iron-alloys in the Seis Lagos Carbonatite Complex-Amazonas-Brazil

    International Nuclear Information System (INIS)

    Wetterle Bonow, C. de; Issler, R.S.

    1980-01-01

    New data on rare earth mineralization and iron-alloys as well as other rare elements in the Seis Lagos Carbonatite Complex are described. Drilling and field work data have permited to define in surface, subsidence zones (subsurface collapses), in the interval of 14.65 to 73.10 meters depth a carbonaceous clay sequence, sapropelic, neogenic, highly enriched in Re, Nb, Th, V, Zn and Be as well as Sc, Y, Ga, Co and Sn as by-products were detected. Sedimentogenic aspects of the enrichment of detect elements, the scintillometric survey, the reserve calculation, the detected elements, the by-products and the complementary study for the deposit are discussed and finaly a value of US$ 6.7 x 10 9 is estimated for the detect deposit. (Author) [pt

  17. Determination of stability constants of iron(III and chromium(III-nitrilotriacetate-methyl cysteine mixed complexes by electrophoretic technique

    Directory of Open Access Journals (Sweden)

    Brij Bhushan Tewari

    2004-06-01

    Full Text Available The stability constants of Fe(III and Cr(III with methyl cysteine and nitrilotriacetate (NTA were determined by paper electrophoretic technique. Beside binary ternary complexes have also been studied, in which nitrilotriacetate and methyl cysteine acts as primary and secondary ligand, respectively. The stability constants of mixed ligand complexes metal (M-nitrilotriacetate-methyl cysteine have been found to be 5.72 plus or minus 0.09 and 5.54 plus or minus 0.11 (log K values for Fe(III and Cr(III complexes, respectively, at 35 oC and ionic strength 0.1 M.

  18. Study on volatilization mechanism of ruthenium tetroxide from nitrosyl ruthenium nitrate by using mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Tetsuya, E-mail: tkato@criepi.denken.or.jp [Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, 2-11-1 Iwado-kita, Komae-shi, Tokyo 201-8511 (Japan); Usami, Tsuyoshi; Tsukada, Takeshi [Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, 2-11-1 Iwado-kita, Komae-shi, Tokyo 201-8511 (Japan); Shibata, Yuki; Kodama, Takashi [Safety Technology Division, Japan Nuclear Fuel Ltd., Obuchi, Rokkasho-mura, Aomori 039-3212 (Japan)

    2016-10-15

    In a cooling malfunction accident of a high-level liquid waste (HLLW) tank, behavior of ruthenium (Ru) attracts much attention, since Ru could be oxidized to a volatile chemical form in the boiling and drying of HLLW, and part of radioactive Ru can potentially be released to the environment. In this study, nitrosyl Ru nitrate (Ru(NO)(NO{sub 3}){sub 3}) dissolved in nitric acid (HNO{sub 3}), which is commonly contained in a simulated HLLW, was dried and heated up to 723 K, and the evolved gas was introduced into a mass spectrometer. The well-known volatile species, ruthenium tetroxide (RuO{sub 4}) was detected in a temperature range between 390 K and 500 K with the peak top around 440 K. Various gases such as HNO{sub 3}, nitrogen dioxide (NO{sub 2}), nitrogen monoxide (NO) also evolved due to evaporation of the nitric acid and decomposition of the nitrate ions. The ion current of RuO{sub 4} seems to increase with the increasing decomposition of nitrate, while the evaporation of HNO{sub 3} decreases. More volatilization of RuO{sub 4} was observed from the HNO{sub 3} solution containing not only Ru(NO)(NO{sub 3}){sub 3} but also cerium nitrate (Ce(NO{sub 3}){sub 3}·6H{sub 2}O) which was added for extra supply of nitrate ion, compared with that from the HNO{sub 3} solution containing only Ru(NO)(NO{sub 3}){sub 3}. These experimental results suggest that Ru could be oxidized to form RuO{sub 4} by the nitrate ion as well as HNO{sub 3}. - Graphical abstract: Ion current intensities of the mass numbers corresponding to O, NO, O{sub 2}, NO{sub 2}, HNO{sub 3}, and RuO{sub 4} obtained in mass spectrometry for dried nitric acid solution containing Ru(NO)(NO{sub 3}){sub 3}. Heating rate: 5 K min{sup −1}, sample solution weight: 6.61 mg, contained Ru weight: 0.56 mg. The ion current of RuO{sub 4} increases with the increasing decomposition of nitrate, while the evaporation of HNO{sub 3} decreases. - Highlights: • Nitrosyl Ru nitrate (Ru(NO)(NO{sub 3}){sub 3}) dissolved in

  19. Nitric Oxide Mediates Activity-Dependent Plasticity of Retinal Bipolar Cell Output via S-Nitrosylation

    Science.gov (United States)

    Tooker, Ryan E.; Lipin, Mikhail Y.; Leuranguer, Valerie; Rozsa, Eva; Bramley, Jayne R.; Harding, Jacqueline L.; Reynolds, Melissa M.

    2013-01-01

    Coding a wide range of light intensities in natural scenes poses a challenge for the retina: adaptation to bright light should not compromise sensitivity to dim light. Here we report a novel form of activity-dependent synaptic plasticity, specifically, a “weighted potentiation” that selectively increases output of Mb-type bipolar cells in the goldfish retina in response to weak inputs but leaves the input–output ratio for strong stimuli unaffected. In retinal slice preparation, strong depolarization of bipolar terminals significantly lowered the threshold for calcium spike initiation, which originated from a shift in activation of voltage-gated calcium currents (ICa) to more negative potentials. The process depended upon glutamate-evoked retrograde nitric oxide (NO) signaling as it was eliminated by pretreatment with an NO synthase blocker, TRIM. The NO-dependent ICa modulation was cGMP independent but could be blocked by N-ethylmaleimide (NEM), indicating that NO acted via an S-nitrosylation mechanism. Importantly, the NO action resulted in a weighted potentiation of Mb output in response to small (≤−30 mV) depolarizations. Coincidentally, light flashes with intensity ≥2.4 × 108 photons/cm2/s lowered the latency of scotopic (≤2.4 × 108 photons/cm2/s) light-evoked calcium spikes in Mb axon terminals in an NEM-sensitive manner, but light responses above cone threshold (≥3.5 × 109 photons/cm2/s) were unaltered. Under bright scotopic/mesopic conditions, this novel form of Mb output potentiation selectively amplifies dim retinal inputs at Mb → ganglion cell synapses. We propose that this process might counteract decreases in retinal sensitivity during light adaptation by preventing the loss of visual information carried by dim scotopic signals. PMID:24305814

  20. [Hemodynamic effects of the synthetic analogue of endogenous nitric oxide (II) donors a dinitrosyl iron complex in hypertensive patients with uncomplicated hypertensive crisis].

    Science.gov (United States)

    Gosteev, A Iu; Zorin, A V; Rodnenkov, O V; Dragnev, A G; Chazov, E I

    2014-01-01

    To examine the antihypertensive effect of the synthetic analogue of the endogenous nitric oxide donors in patients with grades 2-3 hypertension and uncomplicated hypertensive crisis (HC). The study included 30 male patients aged 35 to 73 years (mean age 55.5 ± 10.8 years). All the patients had grades 2-3 essential or secondary hypertension. Thirteen (43.3%) patients were observed to have signs of HC; 17 (56.7%) patients had persistent blood pressure (BP) elevation. A dinitrosyl iron complex was injected in a dose of 1.5 or 3 mg per kg of body weight. The purpose of its administration was to lower BP by at least 20% of its baseline level. No significant side effects associated with the administration of the test drug were recorded when the clinical trial protocol was implemented. All the patients reported fever and facial hyperemia during and 10-20 minutes after injection. They all (100%) showed efficient blood pressure reduction of at least 20% of the baseline level. Blood pressure changes were similar when the agent was administered in doses of 1.5 or 3 mg/kg. At 6-8 minutes after the drug was injected, there was a maximal decrease in blood pressure, then its gradual rise and stabilization at a lower level than the baseline one within the following 8 hours. There were no significant differences in the magnitude of a blood pressure reduction after administration of 1.5 and 3 mg/kg. The findings suggest that the dinitrosyl iron complex is highly effective in treating uncomplicated HC. The antihypertensive effect of the drug persists for 8 hours after its injection, which is very important during prehospital therapy. The drug is well tolerated by patients and causes an insignificant number of side effects.

  1. Oxidative degradation of the organometallic iron(II) complex [Fe{bis[3-(pyridin-2-yl)-1H-imidazol-1-yl]methane}(MeCN)(PMe3)](PF6)2: structure of the ligand decomposition product trapped via coordination to iron(II).

    Science.gov (United States)

    Haslinger, Stefan; Pöthig, Alexander; Cokoja, Mirza; Kühn, Fritz E

    2015-12-01

    Iron is of interest as a catalyst because of its established use in the Haber-Bosch process and because of its high abundance and low toxicity. Nitrogen-heterocyclic carbenes (NHC) are important ligands in homogeneous catalysis and iron-NHC complexes have attracted increasing attention in recent years but still face problems in terms of stability under oxidative conditions. The structure of the iron(II) complex [1,1'-bis(pyridin-2-yl)-2,2-bi(1H-imidazole)-κN(3)][3,3'-bis(pyridin-2-yl-κN)-1,1'-methanediylbi(1H-imidazol-2-yl-κC(2))](trimethylphosphane-κP)iron(II) bis(hexafluoridophosphate), [Fe(C17H14N6)(C16H12N6)(C3H9P)](PF6)2, features coordination by an organic decomposition product of a tetradentate NHC ligand in an axial position. The decomposition product, a C-C-coupled biimidazole, is trapped by coordination to still-intact iron(II) complexes. Insights into the structural features of the organic decomposition products might help to improve the stability of oxidation catalysts under harsh conditions.

  2. Stabilities of thiomolybdate complexes of iron; implications for retention of essential trace elements (Fe, Cu, Mo) in sulfidic waters.

    Science.gov (United States)

    Helz, George R; Erickson, Britt E; Vorlicek, Trent P

    2014-06-01

    In aquatic ecosystems, availabilities of Fe, Mo and Cu potentially limit rates of critical biological processes, including nitrogen fixation, nitrate assimilation and N2O decomposition. During long periods in Earth's history when large parts of the ocean were sulfidic, what prevented these elements' quantitative loss from marine habitats as insoluble sulfide phases? They must have been retained by formation of soluble complexes. Identities of the key ligands are poorly known but probably include thioanions. Here, the first determinations of stability constants for Fe(2+)-[MoS4](2-) complexes in aqueous solution are reported based on measurements of pyrrhotite (hexagonal FeS) solubility under mildly alkaline conditions. Two linear complexes, [FeO(OH)MoS4](3-) and [(Fe2S2)(MoS4)2](4-), best explain the observed solubility variations. Complexes that would be consistent with cuboid cluster structures were less successful, implying that such clusters probably are minor or absent in aqueous solution under the conditions studied. The new data, together with prior data on stabilities of Cu(+)-[MoS4](2-) complexes, are used to explore computationally how competition of Fe(2+) and Cu(+) for [MoS4](2-), as well as competition of [MoS4](2-) and HS(-) for both metals would be resolved in solutions representative of sulfidic natural waters. Thiomolybdate complexes will be most important at sulfide concentrations near the [MoO4](2-)-[MoS4](2-) equivalence point. At lower sulfide concentrations, thiomolybdates are insufficiently stable to be competitive ligands in natural waters and at higher sulfide concentrations HS(-) ligands out-compete thiomolybdates.

  3. Synthesis and characterization of two novel trinuclear oxo-centered, of chromium and iron complexes containing unsaturated carboxylate bridging ligand

    Directory of Open Access Journals (Sweden)

    M. Yazdanbakhsh

    2009-12-01

    Full Text Available Two novel oxo-centered trinuclear compounds, [M2M′O(C3H3O26(H¬2O 3]+ (M = Cr, M′ = Cr, Fe have been synthesized. The complexes were characterized by elemental analysis, infrared and electronic spectroscopy and thermogravimetric analysis (TGA. These complexes contain unsaturated carboxylate bridging ligands that cause them to have potential scopes for polymerization in the solid state by cross-linking of substituents. Bridging coordination modes for carboxylates were indicated by presence of asym (M2M'O vibrations in the infrared spectra.

  4. Electrochemical Polymerization of Iron(III) Polypyridyl Complexes through C-C Coupling of Redox Non-innocent Phenolato Ligands

    NARCIS (Netherlands)

    Unjaroen, Duenpen; Swart, Marcel; Browne, Wesley R

    2017-01-01

    Phenolato moieties impart redox flexibility to metal complexes due their accessible (oxidative) redox chemistry and have been proposed as functional ligand moieties in redox non-innocent ligand based transition metal catalysis. Here, the electro-and spectroelectrochemistry of phenolato based

  5. S-nitrosylated proteins of a medicinal CAM plant Kalanchoe pinnata- ribulose-1,5-bisphosphate carboxylase/oxygenase activity targeted for inhibition.

    Science.gov (United States)

    Abat, Jasmeet K; Mattoo, Autar K; Deswal, Renu

    2008-06-01

    Nitric oxide (NO) is a signaling molecule that affects a myriad of processes in plants. However, the mechanistic details are limited. NO post-translationally modifies proteins by S-nitrosylation of cysteines. The soluble S-nitrosoproteome of a medicinal, crassulacean acid metabolism (CAM) plant, Kalanchoe pinnata, was purified using the biotin switch technique. Nineteen targets were identified by MALDI-TOF mass spectrometry, including proteins associated with carbon, nitrogen and sulfur metabolism, the cytoskeleton, stress and photosynthesis. Some were similar to those previously identified in Arabidopsis thaliana, but kinesin-like protein, glycolate oxidase, putative UDP glucose 4-epimerase and putative DNA topoisomerase II had not been identified as targets previously for any organism. In vitro and in vivo nitrosylation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), one of the targets, was confirmed by immunoblotting. Rubisco plays a central role in photosynthesis, and the effect of S-nitrosylation on its enzymatic activity was determined using NaH14CO3. The NO-releasing compound S-nitrosoglutathione inhibited its activity in a dose-dependent manner suggesting Rubisco inactivation by nitrosylation for the first time.

  6. Suppression by Ghrelin of Porphyromonas gingivalis-Induced Constitutive Nitric Oxide Synthase S-Nitrosylation and Apoptosis in Salivary Gland Acinar Cells

    Directory of Open Access Journals (Sweden)

    Bronislaw L. Slomiany

    2010-01-01

    Full Text Available Oral mucosal inflammatory responses to periodontopathic bacterium, P. gingivalis, and its key virulence factor, LPS, are characterized by a massive rise in epithelial cell apoptosis and the disturbances in NO signaling pathways. Here, we report that the LPS-induced enhancement in rat sublingual salivary gland acinar cell apoptosis and NO generation was associated with the suppression in constitutive nitric oxide synthase (cNOS activity and a marked increase in the activity of inducible nitric oxide synthase (iNOS. We demonstrate that the detrimental effect of the LPS on cNOS was manifested by the enzyme protein S-nitrosylation, that was susceptible to inhibition by iNOS inhibitor, 1400 W. Further, we show that a peptide hormone, ghrelin, countered the LPS-induced changes in apoptosis and cNOS activity. This effect of ghrelin was reflected in the decrease in cNOS S-nitrosylation and the increase in phosphorylation. Our findings imply that P. gingivalis-induced disturbances in the acinar cell NO signaling pathways result from upregulation in iNOS-derived NO that causes cNOS S-nitrosylation that interferes with its activation through phosphorylation. We also show that ghrelin protection against P. gingivalis-induced disturbances involves cNOS activation associated with a decrease in its S-nitrosylation and the increase in phosphorylation.

  7. Acid-base properties and surface complexation modeling of phosphate anion adsorption by wasted low grade iron ore with high phosphorus.

    Science.gov (United States)

    Yuan, Xiaoli; Bai, Chenguang; Xia, Wentang; An, Juan

    2014-08-15

    The adsorption phenomena and specific reaction processes of phosphate onto wasted low grade iron ore with high phosphorus (WLGIOWHP) were studied in this work. Zeta potential and Fourier transform infrared spectroscopy (FTIR) analyses were used to elucidate the interaction mechanism between WLGIOWHP and aqueous solution. The results implied that the main adsorption mechanism was the replacement of surface hydroxyl groups by phosphate via the formation of inner-sphere complex. The adsorption process was characterized by chemical adsorption onto WLGIOWHP. The non-electrostatic model (NEM) was used to simulate the surface adsorption of phosphate onto WLGIOWHP. The total surface site density and protonation constants for NEM (N(T)=1.6×10(-4) mol/g, K(a1)=2.2×10(-4), K(a2)=6.82×10(-9)) were obtained by non-linear data fitting of acid-base titrations. In addition, the NEM was used to establish the surface adsorption complexation modeling of phosphate onto WLGIOWHP. The model successfully predicted the adsorption of phosphate onto WLGIOWHP from municipal wastewater. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Facile and reversible formation of iron(III)-oxo-cerium(IV) adducts from nonheme oxoiron(IV) complexes and cerium(III)

    International Nuclear Information System (INIS)

    Draksharapu, Apparao; Rasheed, Waqas; Klein, Johannes E.M.N.; Que, Lawrence Jr.

    2017-01-01

    Ceric ammonium nitrate (CAN) or Ce IV (NH 4 ) 2 (NO 3 ) 6 is often used in artificial water oxidation and generally considered to be an outer-sphere oxidant. Herein we report the spectroscopic and crystallographic characterization of [(N4Py)Fe III -O-Ce IV (OH 2 )(NO 3 ) 4 ] + (3), a complex obtained from the reaction of [(N4Py)Fe II (NCMe)] 2+ with 2 equiv CAN or [(N4Py)Fe IV =O] 2+ (2) with Ce III (NO 3 ) 3 in MeCN. Surprisingly, the formation of 3 is reversible, the position of the equilibrium being dependent on the MeCN/water ratio of the solvent. These results suggest that the Fe IV and Ce IV centers have comparable reduction potentials. Moreover, the equilibrium entails a change in iron spin state, from S=1 Fe IV in 2 to S=5/2 in 3, which is found to be facile despite the formal spin-forbidden nature of this process. This observation suggests that Fe IV =O complexes may avail of reaction pathways involving multiple spin states having little or no barrier. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Facile and reversible formation of iron(III)-oxo-cerium(IV) adducts from nonheme oxoiron(IV) complexes and cerium(III)

    Energy Technology Data Exchange (ETDEWEB)

    Draksharapu, Apparao; Rasheed, Waqas; Klein, Johannes E.M.N.; Que, Lawrence Jr. [Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN (United States)

    2017-07-24

    Ceric ammonium nitrate (CAN) or Ce{sup IV}(NH{sub 4}){sub 2}(NO{sub 3}){sub 6} is often used in artificial water oxidation and generally considered to be an outer-sphere oxidant. Herein we report the spectroscopic and crystallographic characterization of [(N4Py)Fe{sup III}-O-Ce{sup IV}(OH{sub 2})(NO{sub 3}){sub 4}]{sup +} (3), a complex obtained from the reaction of [(N4Py)Fe{sup II}(NCMe)]{sup 2+} with 2 equiv CAN or [(N4Py)Fe{sup IV}=O]{sup 2+} (2) with Ce{sup III}(NO{sub 3}){sub 3} in MeCN. Surprisingly, the formation of 3 is reversible, the position of the equilibrium being dependent on the MeCN/water ratio of the solvent. These results suggest that the Fe{sup IV} and Ce{sup IV} centers have comparable reduction potentials. Moreover, the equilibrium entails a change in iron spin state, from S=1 Fe{sup IV} in 2 to S=5/2 in 3, which is found to be facile despite the formal spin-forbidden nature of this process. This observation suggests that Fe{sup IV}=O complexes may avail of reaction pathways involving multiple spin states having little or no barrier. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Spectroscopic investigation on kinetics, thermodynamics and mechanism for electron transfer reaction of iron(III) complex with sulphur centered radical in stimulated biological system.

    Science.gov (United States)

    Deepalakshmi, S; Sivalingam, A; Kannadasan, T; Subramaniam, P; Sivakumar, P; Brahadeesh, S T

    2014-04-24

    Electron transfer reactions of biological organic sulphides with several metal ions to generate sulphide radical cations are a great concern in biochemical process. To understand the mechanism, a stimulated biological system having model compounds, iron(III)-bipyridyl complex with thio-diglycolic acid (TDGA) was investigated. Spectroscopic study reveals the kinetics and thermodynamics of the reaction in aqueous perchloric acid medium. The reaction follows first and fractional order of 0.412 with respect to [Fe(bpy)3](3+) and TDGA, respectively. The oxidation is insensitive to variation in [H(+)] but slightly decreases with increase in ionic strength ([I]). Addition of acrylamide, a radical scavenger has no effect on the rate of the reaction. The high negative value of ΔS(#) (-74.3±1.09 J K(-1) mol(-1)) indicates the complex formed has a definite orientation higher than the reactants. Based on the above results, a suitable reaction mechanism for this reaction is proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Theoretical studies on the reaction mechanism of alcohol oxidation by high-valent iron-oxo complex of non-heme ligand.

    Science.gov (United States)

    Cheng, Lin; Wang, Jinping; Wang, Meiyan; Wu, Zhijian

    2010-04-28

    The catalytic mechanism for the oxidation of methanol to formaldehyde and water catalyzed by the biomimetic non-heme iron complex, [(tpa)Fe(IV)O](2+) (tpa = tris(2-pyridylmethyl)amine), is presented by the density functional method B3LYP. Experimentally, acetate and CH(3)CN could be coordinated to the Fe center as the sixth ligand to form the catalyst [(tpa)Fe(IV)=O](2+). To investigate the detailed reaction mechanisms for the two possible ligands, two models (acetate-bound ferryl model A and CH(3)CN-bound ferryl model B) are chosen. In total, six routes have been presented for two models. Our calculations show that both acetate and CH(3)CN could provide reasonable pathways. The calculated energy barriers for these routes are between 19.0 and 23.7 kcal mol(-1) in solution, within the error limits of B3LYP. It is also found that the CH(3)CN molecule acts only as a ligand throughout the reaction cycle. By contrast, the acetate ligand acts as a proton sink to assist the product formation. In addition, the less polarized solvent is more suitable for the alcohol oxidation catalyzed by non-heme model complexes.

  12. Cobalt dinitrosoalkane complexes in the C-H functionalization of olefins.

    Science.gov (United States)

    Schomaker, Jennifer M; Boyd, W Christopher; Stewart, Ian C; Toste, F Dean; Bergman, Robert G

    2008-03-26

    The use of cobalt dinitrosoalkane complexes in the C-H functionalization of alkenes has been demonstrated. Reaction of a series of alkenes with Me4CpCo(CO)2 in the presence of NO generates intermediate cobalt dinitrosoalkane complexes that can be deprotonated alpha to the nitrosyl group and added to various Michael acceptors. The resultant products can then undergo retrocycloaddition reactions in the presence of the original alkene to regenerate the starting cobalt dinitrosoalkane complex and release the functionalized alkene.

  13. Synthesis and Characterization of Divalent Manganese, Iron, and Cobalt Complexes in Tripodal Phenolate/N-Heterocyclic Carbene Ligand Environments

    DEFF Research Database (Denmark)

    Käß, Martina; Hohenberger, Johannes; Adelhardt, Mario

    2014-01-01

    of the ligands is evident. Particularly, the molecular structure of 1in which a pyridine molecule is situated next to the Mn–Cl bondand those of azide complexes 2, 4, and 6 demonstrate the flexibility of these mixed-ligand derivatives, which, in contrast to the corresponding symmetrical TIMENR ligands, allow......Two novel tripodal ligands, (BIMPNMes,Ad,Me)− and (MIMPNMes,Ad,Me)2–, combining two types of donor atoms, namely, NHC and phenolate donors, were synthesized to complete the series of N-anchored ligands, ranging from chelating species with tris(carbene) to tris(phenolate) chelating arms....... The complete ligand series offers a convenient way of tuning the electronic and steric environment around the metal center, thus, allowing for control of the complex’s reactivity. This series of divalent complexes of Mn, Fe, and Co was synthesized and characterized by 1H NMR, IR, and UV/vis spectroscopy...

  14. Iron piano-stool complexes containing NHC ligands outfitted with pendent arms: synthesis, characterization, and screening for catalytic transfer hydrogenation

    Science.gov (United States)

    Parthapratim Das; Thomas Elder; William W. Brennessel; Stephen C. Chmely

    2016-01-01

    Catalysis is a fundamental technology that is widely used in the food, petrochemical, pharmaceutical, and agricultural sectors to produce chemical products on an industrial scale. Well-defined molecular organometallic species are a cornerstone of catalytic methodology, and the activity and selectivity of these complexes can be modulated by judicious choice of metal and...

  15. Large thermal hysteresis for iron(II) spin crossover complexes with N-(pyrid-4-yl)isonicotinamide.

    Science.gov (United States)

    Lochenie, Charles; Bauer, Wolfgang; Railliet, Antoine P; Schlamp, Stephan; Garcia, Yann; Weber, Birgit

    2014-11-03

    A new series of iron(II) 1D coordination polymers with the general formula [FeL1(pina)]·xsolvent with L1 being a tetradentate N2O2(2-) coordinating Schiff-base-like ligand [([3,3']-[1,2-phenylenebis(iminomethylidyne)]bis(2,4-pentanedionato)(2-)-N,N',O(2),O(2)'], and pina being a bridging axial ligand N-(pyrid-4-yl)isonicotinamide, are discussed. The X-ray crystal structure of [FeL1(pina)]·2MeOH was solved for the low-spin state. The compound crystallizes in the monoclinic space group P21/c, and the analysis of the crystal packing reveals the formation of a hydrogen bond network where additional methanol molecules are included. Different magnetic properties are observed for the seven samples analyzed, depending on the nature of the included solvent molecules. The widest hysteresis loop is observed for a fine crystalline sample of composition [FeL1(pina)]·xH2O/MeOH. The 88 K wide thermal hysteresis loop (T1/2↑ = 328 K and T1/2↓ = 240 K) is centered around room temperature and can be repeated without of a loss of the spin transition properties. For the single crystals of [FeL1(pina)]·2MeOH, a 51 K wide hysteresis loop is observed (T1/2↑ = 296 K and T1/2↓ = 245 K) that is also stable for several cycles. For a powder sample of [FeL1(pina)]·0.5H2O·0.5MeOH a cooperative spin transition with a 46 K wide hysteresis loop around room temperature is observed (T1/2↑ = 321 K and T1/2↓ = 275 K). This compound was further investigated using Mössbauer spectroscopy and DSC. Both methods reveal that, in the cooling mode, the spin transition is accompanied by a phase transition while in the heating mode a loss of the included methanol is observed that leads to a loss of the spin transition properties. These results show that the pina ligand was used successfully in a crystal-engineering-like approach to generate 1D coordination polymers and improve their spin crossover properties.

  16. Four-coordinate trispyrazolylboratomanganese and -iron complexes with a pyrazolato co-ligand: syntheses and properties as oxidation catalysts.

    Science.gov (United States)

    Tietz, Thomas; Limberg, Christian; Stösser, Reinhard; Ziemer, Burkhard

    2011-08-29

    A series of complexes of the type [(Tp(R1,R2))M(X)] (Tp = trispyrazolylborato) with R(1)/R(2) combinations Me/tBu, Ph/Me, iPr/iPr, Me/Me and for M = Mn or Fe coordinating [Pz(Me,tBu)](-) (Pz = pyrazolato) or Cl(-) as co-ligand X has been synthesised. Although the chloride complexes were very unreactive and stable in air, the pyrazolato series was far more reactive in contact with oxidants like O(2) and tBuOOH. The [(Tp(R1,R2))M(Pz(Me,tBu))] complexes proved to be active pre-catalysts for the oxidation of cyclohexene with tBuOOH, reaching turnover frequencies (TOFs) ranging between moderate and good in comparison to other manganese catalysts. Cyclohexene-3-one and cyclohexene-3-ol were always found to represent the main products, with cyclohexene oxide occasionally formed as a side product. The ratios of the different oxidation products varied with the reaction conditions: in the case of a peroxide/alkene ratio of 4:1, considerably more ketone than alcohol was obtained and cyclohexene oxide formation was almost negligible, whereas a ratio of 1:10 led to a significant increase of the alcohol proportion and to the formation of at least small amounts of the epoxide. Pre-treatment of the dissolved [(Tp(R1,R2))M(Pz(Me,tBu))] pre-catalysts with O(2) led to product distributions and TOFs that were very similar to those found in the absence of O(2), so that it may be argued that tBuOOH and O(2) both lead to the same active species. The results of EPR spectroscopy and ESI-MS suggest that the initial product of the reaction of [(Tp(Me,Me))Mn(Pz(Me,tBu))] with O(2) contains a Mn(III)(O)(2)Mn(IV) core. Prolonged exposure to O(2) leads to a different dinuclear complex containing three O-bridges and resulting in different TOFs/product distributions. Analogous findings were made for other complexes and formation of these overoxidised products may explain the deviation of the catalytic performances if the reactions are carried out in an O(2) atmosphere. Copyright © 2011 WILEY

  17. Quantitative site-specific reactivity profiling of S-nitrosylation in mouse skeletal muscle using cysteinyl peptide enrichment coupled with mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Su, Dian; Shukla, Anil K.; Chen, Baowei; Kim, Jong-Seo; Nakayasu, Ernesto; Qu, Yi; Aryal, Uma; Weitz, Karl; Clauss, Therese R. W.; Monroe, Matthew E.; Camp II, David G.; Bigelow, Diana J.; Smith, Richard D.; Kulkarni, Rohit N.; Qian, Wei-Jun

    2013-04-01

    S-nitrosylation (SNO) is an important reversible thiol oxidation event that has been increasingly recognized for its role in cell signaling. While many proteins susceptible to S-nitrosylation have been reported, site-specific identification of physiologically relevant SNO modifications remains an analytical challenge due to the low-abundance and labile nature of the modification. Herein we present further improvement and optimization of the recently reported, resin-assisted cysteinyl peptide enrichment protocol for SNO identification and the extension of this application to mouse skeletal muscle to identify specific sites sensitive to S-nitrosylation by quantitative reactivity profiling. The results of our data indicate that the protein- and peptide-level enrichment protocols provide comparable specificity and coverage of SNO-peptide identifications. S-nitrosylation reactivity profiling was performed by quantitatively comparing the site-specific SNO modification levels in samples treated with S-nitrosoglutathione (GSNO), an NO donor, at two different physiologically relevant concentrations (i.e., 10 μM and 100 μM). The reactivity profiling experiments overall identified 489 SNO-modified cysteine sites from 197 proteins with the specificity of 95.2% at the unique-peptide-level based on the percentage of Cys-peptides. Among these sites, 260 sites from 135 proteins were observed with relatively high reactivity to S-nitrosylation; such SNO-sensitive sites are more likely to be physiologically relevant. Many of the SNO-sensitive proteins are preferentially localized in mitochondria, contractile fiber and actin cytoskeleton, suggesting the susceptibility of these subcellular compartments to redox regulation. Moreover, the SNO-sensitive proteins seem to be primarily involved in metabolic pathways, including TCA cycle, glycolysis/gluconeogenesis, glutathione metabolism, and fatty acid metabolism, suggesting the importance of redox regulation in muscle metabolism and

  18. Mössbauer spectroscopic and powder X-ray diffraction studies on incorporation of gaseous organic molecules into intermolecular nano-voids of mixed-valence trinuclear iron pentafluorobenzoate complex

    International Nuclear Information System (INIS)

    Sakai, Yoichi; Onaka, Satoru; Ogiso, Ryo; Takayama, Tsutomu; Takahashi, Masashi; Nakamoto, Tadahiro

    2013-01-01

    Incorporation of gaseous organic molecules into polycrystalline mixed-valence trinuclear iron (Fe 3+ ,Fe 3+ ,Fe 2+ ) pentafluorobenzoate complex Fe 3 O(C 6 F 5 COO) 6 (C 5 H 5 N) 3 with intermolecular nano-voids was studied by 57 Fe-Mössbauer spectroscopic and powder XRD measurements. Organic-molecule incorporation was mainly chased by using iron-valence fluctuation observed in a Mössbauer spectrum, and also researched supportively by a powder XRD technique. (author)

  19. Native iron

    DEFF Research Database (Denmark)

    Brooks, Charles Kent

    2015-01-01

    , a situation unique in the Solar System. In such a world, iron metal is unstable and, as we all know, oxidizes to the ferric iron compounds we call 'rust'. If we require iron metal it must be produced at high temperatures by reacting iron ore, usually a mixture of ferrous (Fe2+) and ferric (Fe3+) oxides (Fe2O3......, hematite, or FeO.Fe2O3, magnetite), with carbon in the form of coke. This is carried out in a blast furnace. Although the Earth's core consists of metallic iron, which may also be present in parts of the mantle, this is inaccessible to us, so we must make our own. In West Greenland, however, some almost...... unique examples of iron metal, otherwise called 'native iron' or 'telluric iron', occur naturally....

  20. Structural characterization of an enantiopure hydroxo-bridged binuclear iron(III) complex with empty one-dimensional helical channels.

    Science.gov (United States)

    Alam, Md Akhtarul; Nethaji, Munirathinum; Ray, Manabendra

    2005-03-07

    A H-bond capable chiral tetradentate ligand, Fe3+, and acetate ion assembles into a hydroxo-bridged binuclear complex with the formula [FeIII2(mu-OH)(mu-OAc)(S-L)2] x 4H2O (1) where H2S-L = S-2-(2-hydroxy-benzylamino)-3-(1H-imidazol-4-yl)-propionic acid. The crystal of 1 contains right-handed one-dimensional (1D) helical channels with 7.3-9.8 A diameter. A similar reaction with a ligand having opposite chirality forms the complex with left-handed helical channels (1a). Heating the crystals of 1 at 95 degrees C under reduced pressure selectively removes three waters from the channel forming an enantiopure porous crystal with empty channels (solvent accessible voids 18% v/v). Intermolecular hydrogen bonding between the imidazole N-H and phenolate oxygen in 1-2 forms a C6 symmetric helix with bridging hydroxo groups pointing inside the channels. All the H-bond capable atoms in the ligand along with one water molecule form an extended H-bonded network throughout the crystal. Exposing the empty channels of 2 to iodine vapor indicates partial filling of the channels with iodine. Crystal data for 1 x 4H2O include the following: hexagonal, P61, a = b = 13.164(3) A, c = 36.305 (11) A, alpha = beta = 90 degrees , gamma = 120 degrees , Z = 6, R1 = 0.0387, wR2 = 0.0842. Crystal data for 1a x 2H2O include the following: hexagonal, P6(5), a = b = 13.151(4) A, c = 36.558(2) A, alpha = beta = 90 degrees , gamma = 120 degrees , Z = 6, R1 = 0.0416, wR2 = 0.1190. Crystal data for 2 x H2O include the following: hexagonal, P61, a = b = 13.160(7) A, c = 36.559 (4) A, alpha = beta = 90 degrees , gamma = 120 degrees , Z = 6, R1 = 0.0574, wR2 = 0.1423.

  1. An Iron Complex with a Bent, O-Coordinated CO2Ligand Discovered by Femtosecond Mid-Infrared Spectroscopy.

    Science.gov (United States)

    Straub, Steffen; Brünker, Paul; Lindner, Jörg; Vöhringer, Peter

    2018-03-06

    The activation of carbon dioxide by transition metals is widely recognized as a key step for utilizing this greenhouse gas as a renewable feedstock for the sustainable production of fine chemicals. However, the dynamics of CO 2 binding and unbinding to and from the ligand sphere of a metal have never been observed in the time domain. The ferrioxalate anion is used in aqueous solution as a unique model system for these dynamics and apply femtosecond UV-pump mid-infrared-probe spectroscopy to explore its photoinduced primary processes in a time-resolved fashion. Following optical excitation, a neutral CO 2 molecule is expelled from the complex within about 500 fs to generate a highly intriguing pentacoordinate ferrous dioxalate that carries a bent carbon dioxide radical anion ligand, that is, a reductively activated form of CO 2 , which is end-on-coordinated to the metal center by one of its two oxygen atoms. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. 1D iron(II) spin crossover complexes with 1,2,4-triazol-4-yl-propanoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Railliet, Antoine P.; Naik, Anil D. [Universite Catholique de Louvain, Institute of Condensed Matter and Nanosciences (Belgium); Rotaru, Aurelian [' Stefan cel Mare' University, Department of Electrical Engineering and Computer Science (Romania); Marchand-Brynaert, Jacqueline; Garcia, Yann, E-mail: yann.garcia@uclouvain.be [Universite Catholique de Louvain, Institute of Condensed Matter and Nanosciences (Belgium)

    2012-03-15

    A series of 1D coordination polymers [Fe(patrz){sub 3}]X{sub 2}{center_dot}solv, (patrz = 1,2,4-triazol-4-yl-propanoic acid; X = BF{sub 4{sup -}}, ClO{sub 4{sup -}}, Cl{sup - }, NO{sub 3}-bar and solv = MeOH or H{sub 2}O) were precipitated from methanol. Their spin crossover properties were studied by temperature dependent SQUID magnetometry and {sup 57}Fe Moessbauer spectroscopy, both for solvated and desolvated complexes. Compounds show gradual incomplete spin crossover with distinct thermochromism, in particular [Fe(patrz){sub 3}](BF{sub 4}){sub 2}{center_dot}MeOH, for which only 27% of Fe{sup II} ions are switched to the low-spin state at 77 K, as determined by a detailed {sup 57}Fe Moessbauer study. Other prominent features of this work are the interesting self assembly of 1D chain with exclusively triazole coordination from patrz ligand despite its ditopic nature and a hysteretic room temperature spin crossover in [Fe(patrz){sub 3}]Cl{sub 2}.

  3. 1D iron(II) spin crossover complexes with 1,2,4-triazol-4-yl-propanoic acid

    International Nuclear Information System (INIS)

    Railliet, Antoine P.; Naik, Anil D.; Rotaru, Aurelian; Marchand-Brynaert, Jacqueline; Garcia, Yann

    2012-01-01

    A series of 1D coordination polymers [Fe(patrz) 3 ]X 2 ·solv, (patrz = 1,2,4-triazol-4-yl-propanoic acid; X = BF 4 - , ClO 4 - , Cl  −  , NO 3 -bar and solv = MeOH or H 2 O) were precipitated from methanol. Their spin crossover properties were studied by temperature dependent SQUID magnetometry and 57 Fe Mössbauer spectroscopy, both for solvated and desolvated complexes. Compounds show gradual incomplete spin crossover with distinct thermochromism, in particular [Fe(patrz) 3 ](BF 4 ) 2 ·MeOH, for which only 27% of Fe II ions are switched to the low-spin state at 77 K, as determined by a detailed 57 Fe Mössbauer study. Other prominent features of this work are the interesting self assembly of 1D chain with exclusively triazole coordination from patrz ligand despite its ditopic nature and a hysteretic room temperature spin crossover in [Fe(patrz) 3 ]Cl 2 .

  4. AFM and electron microscopy study of the unusual aggregation behavior of metallosurfactants based on iron(II) complexes with bipyridine ligands.

    Science.gov (United States)

    Garcia, Paula; Eaton, Peter; Geurts, Huub P M; Sousa, Miguel; Gameiro, Paula; Feiters, Martin C; Nolte, Roeland J M; Pereira, Eulalia; de Castro, Baltazar

    2007-07-17

    The aggregation behavior in water-rich solutions of five iron(II) complexes with alkylated derivatives of 2,2'-bipyridine was studied by electron microscopy (cryo-SEM, SEM, and TEM) and AFM. The results obtained by cryo-SEM on frozen colloidal solutions show that the morphology of the aggregates strongly depends on the length of the alkyl chains in the bipyridine ligands, with shorter alkyl chains forming rod-like structures, whereas for compounds with longer alkyl chains, only spherical structures were detected. The self-aggregates were further characterized by SEM and TEM. The results show that their overall morphology depends only on the length of the alkyl chain of the bipyridine ligands and that the samples show a broad size distribution. In addition, TEM and SEM were used to study the stability of the self-aggregates in solution, the effect of addition of methanol, and the temperature used in the preparation of the colloidal solutions. AFM studies of the aggregates either dried in ambient conditions or dehydrated by long drying under vacuum showed partially collapsed self-aggregates in the latter case, showing that the aggregates contain water in their core, indicating that the self-aggregation leads to vesicle-type structures.

  5. Spin Crossover in Dinuclear N4S2 Iron(II) Thioether-Triazole Complexes: Access to [HS-HS], [HS-LS], and [LS-LS] States.

    Science.gov (United States)

    Hogue, Ross W; Feltham, Humphrey L C; Miller, Reece G; Brooker, Sally

    2016-05-02

    Access to a new family of thioether-linked PSRT ligands, 4-substituted-3,5-bis{[(2-pyridylmethyl)sulfanyl]methyl}-4H-1,2,4-triazoles (analogues of the previously studied amino-linked PMRT ligands), has been established. Four such ligands have been prepared, PSPhT, PS(i)BuT, PS(t-Bu)PhT, and PS(Me)PhT, with R = Ph, (i)Bu, (t-Bu)Ph, and (Me)Ph, respectively. Three dinuclear colorless to pale green iron(II) complexes, [Fe(II)2(PSRT)2](BF4)4·solvent, featuring N4S2 donor sets, were prepared. Single-crystal structure determinations on [Fe(II)2(PSPhT)2](BF4)4·2MeCN·H2O, [Fe(II)2(PSPhT)2](BF4)4·2(1)/2MeCN·(1)/2H2O·THF, [Fe(II)2(PS(Me)PhT)2](BF4)4·2MeCN, and [Fe(II)2(PS(i)BuT)2](BF4)4·4MeCN reveal that all four are stabilized in the [HS-HS] state to 100 K and that both possible binding modes of the bis-terdentate ligands, cis- and trans-axial, are observed. Variable-temperature magnetic susceptibility studies of air-dried crystals (solvatomorphs of the single crystal samples) reveal the first examples of spin crossover (SCO) for a dinuclear iron(II) complex with N4S2 coordination. Specifically, [Fe(II)2(PSPhT)2](BF4)4·2(1)/2H2O undergoes a multistep but complete SCO from [HS-HS] to [LS-LS], whereas [Fe(II)2(PS(Me)PhT)2](BF4)4·1(1)/2MeCN·2H2O exhibits a half-SCO from [HS-HS] to [HS-LS]. In contrast, [Fe(II)2(PS(i)BuT)2](BF4)4·MeCN·H2O remains [HS-HS] down to 50 K. The reflectance spectrum of pale green [Fe(II)2(PSPhT)2](BF4)4·(1)/2CHCl3·2(1)/2H2O (solvatomorph A) reveals a trace of LS character (572 nm band (1)A1g → (1)T1g). Evans' (1)H NMR method and UV-vis spectroscopy studies revealed that on cooling dark green acetonitrile solutions of these complexes from 313 to 233 K, all three undergo SCO centered at or near room temperature. The tendency of the complexes to go LS in solution reflects the electronic impact of R on the σ-donor strength of the PSRT ligand, whereas the opposite trend in stabilization of the LS state is seen in the solid state, where

  6. Quantum chemical studies on electronic structure and photodynamics of ruthenium complexes

    International Nuclear Information System (INIS)

    Freitag, L.

    2015-01-01

    Ruthenium complexes have found their way into many applications in the last decades. Among those, ruthenium polypyridyl compounds have been employed as light harvesting devices and photosensitisers in artificial photosynthesis and molecular photocatalysis. Ruthenium nitrosyl complexes are rapidly emerging as NO delivery agents to biological tissues with promising applications in anticancer photodynamic therapy, thanks to their ability to photorelease nitric oxide (NO). This thesis encompasses computational studies on reactivity, electronic structure, excited states and photodynamics of several ruthenium nitrosyl and polypyridyl complexes. The first part of the thesis deals with ruthenium nitrosyls. The cis-trans isomerisation mechanism of RuHIndNO, a ruthenium nitrosyl derivate of the prominent anti-cancer drug candidate KP1019, is investigated with density functional theory calculations. Next, the electronic structure of the ground and the first excited triplet state of RuHIndNO is studied with multiconfigurational methods including the density-matrix renormalisation group (DMRG). The obtained multiconfigurational wavefunctions and DMRG-based orbital entanglement analysis provides theoretical insight into the non-innocence of the NO ligand in nitrosyl complexes by describing the electron correlation in the Ru--NO bond and assigning oxidation states to the metal and the NO ligand. Another study is performed on excited states of ruthenium nitrosyl complexes with quantum chemical calculations and surface-hopping dynamics to obtain insights into the photodissociation mechanism of NO. The second part of this thesis is devoted to the excited states and photophysics of ruthenium polypyridyl complexes. Accurate excitation energies of tris(2,2-bipyridine)ruthenium (II), the prototype ruthenium polypyridyl are obtained with multiconfigurational calculations assisted by an orbital entanglement analysis. Subsequently, the effect of the ligand substitution on the photophysics

  7. Mitochondrial Iron Transport and Homeostasis in Plants

    Directory of Open Access Journals (Sweden)

    Anshika eJain

    2013-09-01

    Full Text Available Iron (Fe is an essential nutrient for plants and although the mechanisms controlling iron uptake from the soil are relatively well understood, comparatively little is known about subcellular trafficking of iron in plant cells. Mitochondria represent a significant iron sink within cells, as iron is required for the proper functioning of respiratory chain protein complexes. Mitochondria are a site of Fe-S cluster synthesis, and possibly heme synthesis as well. Here we review recent insights into the molecular mechanisms controlling mitochondrial iron transport and homeostasis. We focus on the recent identification of a mitochondrial iron uptake transporter in rice and a possible role for metalloreductases in iron uptake by mitochondria. In addition, we highlight recent advances in mitochondrial iron homeostasis with an emphasis on the roles of frataxin and ferritin in iron trafficking and storage within mitochondria.

  8. Novel carbon-supported Fe-N electrocatalysts synthesized through heat treatment of iron tripyridyl triazine complexes for the PEM fuel cell oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Cicero W.B. [Institute for Fuel Cell Innovation, National Research Council of (Canada); Department of Chemistry, Universidade Federal do Maranhao, Av. dos Portugueses, S/N 65.080-040 Sao Luis, MA (Brazil); Zhang, Lei; Lee, Kunchan; Liu, Hansan; Zhang, Jianlu; Wu, Shaohong; Zhang, Jiujun [Institute for Fuel Cell Innovation, National Research Council of (Canada); Marques, Aldalea L.B. [Department of Technology Chemistry, Universidade Federal do Maranhao, Sao Luis, MA (Brazil); Marques, Edmar P. [Department of Chemistry, Universidade Federal do Maranhao, Av. dos Portugueses, S/N 65.080-040 Sao Luis, MA (Brazil); Shi, Zheng

    2008-11-01

    2,4,6-Tris(2-pyridyl)-1,3,5-triazine (TPTZ) was used as a ligand to prepare iron-TPTZ (Fe-TPTZ) complexes for the development of a new oxygen reduction reaction (ORR) catalyst. The prepared Fe-TPTZ complexes were then heat-treated at temperatures ranging from 400 C to 1100 C to obtain carbon-supported Fe-N catalysts (Fe-N/C). These catalysts were characterized in terms of catalyst composition, structure, and morphology by several instrumental methods such as energy dispersive X-ray, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. With respect to the ORR activity, the Fe-N/C catalysts were also evaluated by cyclic voltammetry, as well as rotating disk and ring-disk electrodes. The results showed that among the heat-treated catalysts, that obtained at a heat-treatment temperature of 800 C is the most active ORR catalyst. The overall electron transfer number for the catalyzed ORR was determined to be between 3.5 and 3.8, with 10-30% H{sub 2}O{sub 2} production. The ORR catalytic activity of this catalyst was also tested in a hydrogen-air proton exchange membrane (PEM) fuel cell. At a cell voltage of 0.30 V, this fuel cell can give a current density of 0.23 A cm{sup -2} with a maximum MEA power density of 0.070 W cm{sup -2} indicating that this catalyst has potential to be used as a non-noble catalyst in PEM fuel cells. (author)

  9. Uranium(VI) sorption on iron oxides in Hanford Site sediment: Application of a surface complexation model

    International Nuclear Information System (INIS)

    Um, Wooyong; Serne, R. Jeffrey; Brown, Christopher F.; Rod, Kenton A.

    2008-01-01

    Sorption of U(VI) on Hanford fine sand (HFS) with varying Fe-oxide (especially ferrihydrite) contents showed that U(VI) sorption increased with the incremental addition of synthetic ferrihydrite into HFS, consistent with ferrihydrite being one of the most reactive U(VI) sorbents present in natural sediments. Surface complexation model (SCM) calculations for U(VI) sorption, using only U(VI) surface-reaction constants obtained from U(VI) sorption data on freshly synthesized ferrihydrite at different pHs, were similar to the measured U(VI) sorption results on pure synthetic ferrihydrite and on HFS with high contents of ferrihydrite (5 wt%) added. However, the SCM prediction using only U(VI) sorption reactions and constants for synthetic ferrihydrite overestimated U(VI) sorption on the natural HFS or HFS with addition of low amounts of added ferrihydrite (1 wt% added). Over-predicted U(VI) sorption was attributed to reduced reactivity of natural ferrihydrite present in Hanford Site sediments, compared to freshly prepared synthetic ferrihydrite. Even though the SCM general composite (GC) approach is considered to be a semi-quantitative estimation technique for contaminant sorption, which requires systematic experimental data on the sorbent-sorbate system being studied to obtain credible SCM parameters, the general composite SCM model was still found to be a useful technique for describing U(VI) sorption on natural sediments. Based on U(VI) batch sorption results, two simple U(VI) monodentate surface species, SO U O 2 HCO 3 and SO U O 2 OH on ferrihydrite and phyllosillicate in HFS, respectively, can be successfully used to describe U(VI) sorption onto Hanford Site sediment contacting varying geochemical solutions

  10. A critical look at the calculation of the binding characteristics and concentration of iron complexing ligands in seawater with suggested improvements

    NARCIS (Netherlands)

    Gerringa, L.J.A.; Rijkenberg, M.J.A.; Thuróczy, C.-E.; Maas, L.R.M.

    2014-01-01

    Environmental context
    The low concentration of iron in the oceans limits growth of phytoplankton. Dissolved organic molecules, called ligands, naturally present in seawater, bind iron thereby increasing its solubility and, consequently, its availability for biological uptake by phytoplankton. The

  11. O2-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation

    International Nuclear Information System (INIS)

    Ascenzi, Paolo; Gullotta, Francesca; Gioia, Magda; Coletta, Massimo; Fasano, Mauro

    2011-01-01

    Research highlights: → Human serum heme-albumin displays globin-like properties. → O 2 -mediated oxidation of ferrous nitrosylated human serum heme-albumin. → Allosteric modulation of human serum heme-albumin reactivity. → Rifampicin is an allosteric effector of human serum heme-albumin. → Human serum heme-albumin is a ROS and NOS scavenger. -- Abstract: Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O 2 -mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O 2 -mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k = 9.8 x 10 -5 and 8.3 x 10 -4 s -1 , and h = 1.3 x 10 -4 and 8.5 x 10 -4 s -1 , in the absence and presence of rifampicin, respectively, at pH = 7.0 and T = 20.0 o C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O 2 -mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O 2 does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O 2 -mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

  12. Evaluation of umbilical cord mesenchymal stem cells labeling with superparamagnetic iron oxide nanoparticles coated with dextran and complexed with Poly-L-Lysine; Avaliacao da marcacao de celulas-tronco mesenquimais de cordao umbilical com nanoparticulas superparamagneticas de oxido de ferro recobertas com Dextran e complexadas a Poli-L-Lisina

    Energy Technology Data Exchange (ETDEWEB)

    Sibov, Tatiana Tais; Mamani, Javier Bustamante; Pavon, Lorena Favaro; Cardenas, Walter Humberto; Gamarra, Lionel Fernel, E-mail: tatianats@einstein.br [Instituto do Cerebro - InCe, Hospital Israelita Albert Einstein - HIAE, Sao Paulo, SP (Brazil); Miyaki, Liza Aya Mabuchi [Faculdade de Enfermagem, Hospital Israelita Albert Einstein - HIAE, Sao Paulo, SP (Brazil); Marti, Luciana Cavalheiro; Sardinha, Luiz Roberto [Centro de Pesquisa Experimental, Hospital Israelita Albert Einstein - HIAE, Sao Paulo, SP (Brazil); Oliveira, Daniela Mara de [Universidade de Brasilia - UnB, Brasilia, DF (Brazil)

    2012-04-15

    Objective: The objective of this study was to evaluate the effect of the labeling of umbilical cord vein derived mesenchymal stem cells with superparamagnetic iron oxide nanoparticles coated with dextran and complexed to a non-viral transfector agent transfector poly-L-lysine. Methods: The labeling of mesenchymal stem cells was performed using the superparamagnetic iron oxide nanoparticles/dextran complexed and not complexed to poly-L-lysine. Superparamagnetic iron oxide nanoparticles/dextran was incubated with poly-L-lysine in an ultrasonic sonicator at 37 deg C for 10 minutes for complex formation superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine by electrostatic interaction. Then, the mesenchymal stem cells were incubated overnight with the complex superparamagnetic iron oxide nanoparticles/dextran/poly-L-lysine and superparamagnetic iron oxide nanoparticles/dextran. After the incubation period the mesenchymal stem cells were evaluated by internalization of the complex superparamagnetic iron oxide nanoparticles/dextran/polyL-lysine and superparamagnetic iron oxide nanoparticles/dextran by Prussian Blue stain. Cellular viability of labeled mesenchymal stem cells was evaluated by cellular proliferation assay using 5,6-carboxyfluorescein-succinimidyl ester method and apoptosis detection by Annexin V- Propidium Iodide assay. Results: mesenchymal stem cells labeled with superparamagnetic iron oxide nanoparticles/ dextran without poly-L-lysine not internalized efficiently the superparamagnetic iron oxide nanoparticles due to its low presence detected within cells. Mesenchymal stem cells labeled with the complex superparamagnetic iron oxide nanoparticles/dextran/polyL-lysine efficiently internalized the superparamagnetic iron oxide nanoparticles due to greater presence in the cells interior. The viability and apoptosis assays demonstrated that the mesenchymal stem cells labeled and not labeled respectively with the superparamagnetic iron oxide

  13. SOD1 aggregation in astrocytes following ischemia/reperfusion injury: a role of NO-mediated S-nitrosylation of protein disulfide isomerase (PDI).

    Science.gov (United States)

    Chen, Xueping; Guan, Teng; Li, Chen; Shang, Huifang; Cui, Liying; Li, Xin-Min; Kong, Jiming

    2012-10-12

    Ubiquitinated-protein aggregates are implicated in cerebral ischemia/reperfusion injury. The very presence of these ubiquitinated-protein aggregates is abnormal and seems to be disease-related. However, it is not clear what leads to aggregate formation and whether the aggregations represent a reaction to aggregate-mediated neurodegeneration. To study the nitrosative stress-induced protein aggregation in cerebral ischemia/reperfusion injury, we used primary astrocyte cultures as a cell model, and systematically examined their iNOS expression and consequent NO generation following oxygen glucose deprivation and reperfusion. The expression of protein disulfide isomerase (PDI) and copper-zinc superoxide dismutase (SOD1) were also examined, and the biochemical interaction between PDI and SOD1 was determined by immunoprecipitation. In addition, the levels of S-nitrosylated PDI in cultured astrocytes after oxygen glucose deprivation and reperfusion treatment were measured using the biotin-switch assay. The formation of ubiquitinated-protein aggregates was detected by immunoblot and immunofluorescence staining. Our data showed that the up-regulation of iNOS expression after oxygen glucose deprivation and reperfusion treatment led to excessive NO generation. Up-regulation of PDI and SOD1 was also identified in cultured astrocytes following oxygen glucose deprivation and reperfusion, and these two proteins were found to bind to each other. Furthermore, the increased nitrosative stress due to ischemia/reperfusion injury was highly associated with NO-induced S-nitrosylation of PDI, and this S-nitrosylation of PDI was correlated with the formation of ubiquitinated-protein aggregates; the levels of S-nitrosylated PDI increased in parallel with the formation of aggregates. When NO generation was pharmacologically inhibited by iNOS specific inhibitor 1400W, S-nitrosylation of PDI was significantly blocked. In addition, the formation of ubiquitinated-protein aggregates in cultured

  14. SOD1 aggregation in astrocytes following ischemia/reperfusion injury: a role of NO-mediated S-nitrosylation of protein disulfide isomerase (PDI

    Directory of Open Access Journals (Sweden)

    Chen Xueping

    2012-10-01

    Full Text Available Abstract Background Ubiquitinated-protein aggregates are implicated in cerebral ischemia/reperfusion injury. The very presence of these ubiquitinated-protein aggregates is abnormal and seems to be disease-related. However, it is not clear what leads to aggregate formation and whether the aggregations represent a reaction to aggregate-mediated neurodegeneration. Methods To study the nitrosative stress-induced protein aggregation in cerebral ischemia/reperfusion injury, we used primary astrocyte cultures as a cell model, and systematically examined their iNOS expression and consequent NO generation following oxygen glucose deprivation and reperfusion. The expression of protein disulfide isomerase (PDI and copper-zinc superoxide dismutase (SOD1 were also examined, and the biochemical interaction between PDI and SOD1 was determined by immunoprecipitation. In addition, the levels of S-nitrosylated PDI in cultured astrocytes after oxygen glucose deprivation and reperfusion treatment were measured using the biotin-switch assay. The formation of ubiquitinated-protein aggregates was detected by immunoblot and immunofluorescence staining. Results Our data showed that the up-regulation of iNOS expression after oxygen glucose deprivation and reperfusion treatment led to excessive NO generation. Up-regulation of PDI and SOD1 was also identified in cultured astrocytes following oxygen glucose deprivation and reperfusion, and these two proteins were found to bind to each other. Furthermore, the increased nitrosative stress due to ischemia/reperfusion injury was highly associated with NO-induced S-nitrosylation of PDI, and this S-nitrosylation of PDI was correlated with the formation of ubiquitinated-protein aggregates; the levels of S-nitrosylated PDI increased in parallel with the formation of aggregates. When NO generation was pharmacologically inhibited by iNOS specific inhibitor 1400W, S-nitrosylation of PDI was significantly blocked. In addition, the

  15. COMPLEMENTARY USE OF INFORMATION FROM SPACE-BASED DINSAR AND FIELD MEASURING SYSTEMS FOR OPERATIONAL MONITORING PURPOSES IN OPEN PIT IRON MINES OF CARAJÁS MINING COMPLEX (BRAZILIAN AMAZON REGION)

    OpenAIRE

    W. R. Paradella; J. C. Mura; F. F. Gama; A. R. Santos; G. G. Silva; M. Galo; P. O. Camargo; A. Q. Silva

    2015-01-01

    Now spanning five simultaneous open-pit operations with exploration carried out through open pit benching, Carajás complex encompasses the world´s largest iron reserves. Open pit mining operations in the area can lead to slope instabilities with risks to personnel, equipment and production due to intense excavations in rock products of low geomechanical quality, blasting practices and heavy precipitation. Thus, an effective prediction and management of surface deformations should be ...

  16. Cofortification of ferric pyrophosphate and citric acid/trisodium citrate into extruded rice grains doubles iron bioavailability through in situ generation of soluble ferric pyrophosphate citrate complexes.

    Science.gov (United States)

    Hackl, Laura; Cercamondi, Colin I; Zeder, Christophe; Wild, Daniela; Adelmann, Horst; Zimmermann, Michael B; Moretti, Diego

    2016-05-01

    Iron fortification of rice is a promising strategy for improving iron nutrition. However, it is technically challenging because rice is consumed as intact grains, and ferric pyrophosphate (FePP), which is usually used for rice fortification, has low bioavailability. We investigated whether the addition of a citric acid/trisodium citrate (CA/TSC) mixture before extrusion increases iron absorption in humans from FePP-fortified extruded rice grains. We conducted an iron absorption study in iron-sufficient young women (n = 20), in which each participant consumed 4 different meals (4 mg Fe/meal): 1) extruded FePP-fortified rice (No CA/TSC); 2) extruded FePP-fortified rice with CA/TSC added before extrusion (CA/TSC extruded); 3) extruded FePP-fortified rice with CA/TSC solution added after cooking and before consumption (CA/TSC solution); and 4) nonextruded rice fortified with a FeSO4 solution added after cooking and before consumption (reference). Iron absorption was calculated from erythrocyte incorporation of stable iron isotopes 14 d after administration. In in vitro experiments, we assessed the soluble and dialyzable iron from rice meals in which CA/TSC was added at different preparation stages and from meals with different iron:CA:TSC ratios. Fractional iron absorption was significantly higher from CA/TSC-extruded meals (3.2%) than from No CA/TSC (1.7%) and CA/TSC solution (1.7%; all P solubility and dialyzability were higher in CA/TSC-extruded rice than in rice with No CA/TSC and CA/TSC solution, and solubility increased with higher amounts of added CA and TSC in extruded rice. Iron bioavailability nearly doubled when CA/TSC was extruded with FePP into fortified rice, resulting in iron bioavailability comparable to that of FeSO4 We attribute this effect to an in situ generation of soluble FePP citrate moieties during extrusion and/or cooking because of the close physical proximity of FePP and CA/TSC in the extruded rice matrix. This trial was registered at

  17. Complex Interaction of Deferasirox and Pythium insidiosum: Iron-Dependent Attenuation of Growth In Vitro and Immunotherapy-Like Enhancement of Immune Responses In Vivo

    Science.gov (United States)

    Zanette, Régis A.; Bitencourt, Paula E. R.; Kontoyiannis, Dimitrios P.; Fighera, Rafael A.; Flores, Mariana M.; Kommers, Glaucia D.; Silva, Priscila S.; Ludwig, Aline; Moretto, Maria B.; Alves, Sydney H.; Santurio, Janio M.

    2015-01-01

    Pythium insidiosum iron acquisition mechanisms are unknown. We previously showed that the iron chelator deferasirox had weak activity in vitro and in rabbits with experimental pythiosis. Here we show that deferasirox causes damage to P. insidiosum hyphae in vitro, but that activity is diminished in the presence of exogenous iron. The tissue activity of the proinflammatory enzyme adenosine deaminase and the histological pattern observed in pythiosis lesions of rabbits treated with deferasirox were similar to the ones in animals treated with immunotherapy. PMID:25738758

  18. Complex interaction of deferasirox and Pythium insidiosum: iron-dependent attenuation of growth in vitro and immunotherapy-like enhancement of immune responses in vivo.

    Directory of Open Access Journals (Sweden)

    Régis A Zanette

    Full Text Available Pythium insidiosum iron acquisition mechanisms are unknown. We previously showed that the iron chelator deferasirox had weak activity in vitro and in rabbits with experimental pythiosis. Here we show that deferasirox causes damage to P. insidiosum hyphae in vitro, but that activity is diminished in the presence of exogenous iron. The tissue activity of the proinflammatory enzyme adenosine deaminase and the histological pattern observed in pythiosis lesions of rabbits treated with deferasirox were similar to the ones in animals treated with immunotherapy.

  19. Ligand iron catalysts for selective hydrogenation

    Science.gov (United States)

    Casey, Charles P.; Guan, Hairong

    2010-11-16

    Disclosed are iron ligand catalysts for selective hydrogenation of aldehydes, ketones and imines. A catalyst such as dicarbonyl iron hydride hydroxycyclopentadiene) complex uses the OH on the five member ring and hydrogen linked to the iron to facilitate hydrogenation reactions, particularly in the presence of hydrogen gas.

  20. Mechanistic Study of Monodisperse Iron Oxide Nanocrystals ...

    African Journals Online (AJOL)

    To gain better insight into the formation of iron oxide nanocrystals from the solution phase thermal decomposition of iron (III) oleate complex, different reaction conditions including time, heating ramp, as well as concentrations of iron oleate precursor and oleic acid ligand were systematically varied and the resulting ...

  1. Down regulation of NO signaling in Trypanosoma cruzi upon parasite-extracellular matrix interaction: changes in protein modification by nitrosylation and nitration.

    Directory of Open Access Journals (Sweden)

    Milton Pereira

    2015-04-01

    Full Text Available Adhesion of the Trypanosoma cruzi trypomastigotes, the causative agent of Chagas' disease in humans, to components of the extracellular matrix (ECM is an important step in host cell invasion. The signaling events triggered in the parasite upon binding to ECM are less explored and, to our knowledge, there is no data available regarding •NO signaling.Trypomastigotes were incubated with ECM for different periods of time. Nitrated and S-nitrosylated proteins were analyzed by Western blotting using anti-nitrotyrosine and S-nitrosyl cysteine antibodies. At 2 h incubation time, a decrease in NO synthase activity, •NO, citrulline, arginine and cGMP concentrations, as well as the protein modifications levels have been observed in the parasite. The modified proteins were enriched by immunoprecipitation with anti-nitrotyrosine antibodies (nitrated proteins or by the biotin switch method (S-nitrosylated proteins and identified by MS/MS. The presence of both modifications was confirmed in proteins of interest by immunoblotting or immunoprecipitation.For the first time it was shown that T. cruzi proteins are amenable to modifications by S-nitrosylation and nitration. When T. cruzi trypomastigotes are incubated with the extracellular matrix there is a general down regulation of these reactions, including a decrease in both NOS activity and cGMP concentration. Notwithstanding, some specific proteins, such as enolase or histones had, at least, their nitration levels increased. This suggests that post-translational modifications of T. cruzi proteins are not only a reflex of NOS activity, implying other mechanisms that circumvent a relatively low synthesis of •NO. In conclusion, the extracellular matrix, a cell surrounding layer of macromolecules that have to be trespassed by the parasite in order to be internalized into host cells, contributes to the modification of •NO signaling in the parasite, probably an essential move for the ensuing invasion step.

  2. Synthesis of iron oxides nanoparticles with very high saturation magnetization form TEA-Fe(III) complex via electrochemical deposition for supercapacitor applications

    Science.gov (United States)

    Elrouby, Mahmoud; Abdel-Mawgoud, A. M.; El-Rahman, Rehab Abd

    2017-11-01

    This work is devoted to the synthesis of magnetic iron oxides nanoparticles with very high saturation magnetization to be qualified for supercapacitor applications using, a simple electrodeposition technique. It is found that the electrochemical reduction process depends on concentration, temperature, deposition potential and the scan rate of potential. The nature of electrodeposition process has been characterized via voltammetric and chronoamperometric techniques. The morphology of the electrodeposits has been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure and phase content of these investigated electrodeposits have been examined and calculated. The obtained iron oxides show a high saturation magnetization (Ms) of about 229 emu g-1. The data exhibited a relation between Ms of electrodeposited iron oxide and specific capacitance. This relation exhibits that the highest Ms value of electrodeposited iron oxides gives also highest specific capacitance of about 725 Fg-1. Moreover, the electrodeposited iron oxides exhibit a very good stability. The new characteristics of the electro synthesized iron oxides at our optimized conditions, strongly qualify them as a valuable material for high-performance supercapacitor applications.

  3. EPR Insensitivity of the Metal-Nitrosyl Spin-Bearing Moiety in Complexes [Ln RuII-NO.DEG.]k

    Czech Academy of Sciences Publication Activity Database

    Frantz, S.; Sarkar, B.; Sieger, M.; Kaim, W.; Roncaroli, F.; Olabe, J. A.; Záliš, Stanislav

    -, č. 14 (2004), s. 2902-2907 ISSN 1434-1948 R&D Projects: GA MŠk OC D14.20 Institutional research plan: CEZ:AV0Z4040901 Keywords : density functional calculations * EPR spectroscopy * nitric oxide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.336, year: 2004

  4. Iron refractory iron deficiency anemia

    Science.gov (United States)

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

  5. Accelerated dissolution of iron oxides in ice

    Directory of Open Access Journals (Sweden)

    D. Jeong

    2012-11-01

    Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

  6. Aqua complex of iron(III) and 5-chloro-3-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-2-hydroxybenzenesulfonate: Structure and catalytic activity in Henry reaction

    Science.gov (United States)

    Mahmudov, Kamran T.; Kopylovich, Maximilian N.; Haukka, Matti; Mahmudova, Gunay S.; Esmaeila, Espandi F.; Chyragov, Famil M.; Pombeiro, Armando J. L.

    2013-09-01

    A water-soluble iron(III) complex [Fe(H2O)3(L)]·5H2O (1) was prepared by reaction of iron(III) chloride with 5-chloro-3-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-2-hydroxy-benzenesulfonic acid (H3L). The complex was characterized by IR, 1H NMR and ESI-MS spectroscopies, elemental and X-ray crystal structural analyses. The coordination environment of the central iron(III) is a distorted octahedron, three sites being occupied by L3- ligand, which chelates in O,N,O fashion, while three other sites are filled with the water molecules. The uncoordinated water molecules are held in the channels of the overall 3D supramolecular structure by the carbonyl and sulfonyl groups of L3- and the ligated waters. Apart from the multiple hydrogen bonds, an intermolecular charge-assisted O···Cl halogen bonding with 3.044 Å distance was described. 1 acts as an effective catalyst in the Henry reaction producing nitroaldols from nitroethane and various aldehydes with yields up to 90% and threo/erythro diastereoselectivity ranging from 3:1 to 1:1.

  7. Self-Assembly with 2,6-Bis(1-(pyridin-4-ylmethyl-1H-1,2,3-triazol-4-ylpyridine: Silver(I and Iron(II Complexes

    Directory of Open Access Journals (Sweden)

    Daniel A. W. Ross

    2017-10-01

    Full Text Available A new “click” ligand, 2,6-bis(1-(pyridin-4-ylmethyl-1H-1,2,3-triazol-4-ylpyridine (L featuring a tridentate 2,6-bis(1,2,3-triazol-4-ylpyridine (tripy pocket and two pyridyl (py units was synthesized in modest yield (42% using the copper(I catalyzed azide-alkyne cycloaddition (CuAAC reaction. The coordination chemistry of the ligand with silver(I and iron(II ions was examined using a battery of solution (1H and DOSY (diffusion ordered spectroscopy nuclear magnetic resonance (NMR, infrared and absorption spectroscopies, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS, and solid state (X-ray crystallography, elemental analysis techniques. When treated with silver(I ions, the ligand forms discrete [Ag(L]+ (X−, where X− = BF4−, NO3− or SbF6− complexes in dimethyl sulfoxide (DMSO solution but these complexes crystallize as coordination polymers. The addition of [Fe(H2O6](BF42 to an acetonitrile solution of the ligand forms the expected monomeric octahedral [Fe(L2]2+ complex and treatment of the iron(II complex with AgBF4 generates a heterometallic linear coordination polymer.

  8. Single sheet iron oxides

    DEFF Research Database (Denmark)

    Yin, Zhou

    activity. LDH single sheets have been reported to be effective sorbents, catalysts in electrochemical and photochemical reactions, and building thin films together with other nanomaterials for designing new functionalities. Here we focus on the delamination of FeII-FeIII LDHs into single sheet iron oxide...... was rapid compared to other iron oxides, reaching equilibrium within 60 minutes. Arsenic sorption and acid-base titration data could be successfully described with a 1pk Basic Stern Model (BSM). The point of zero charge was around 8. The intrinsic surface complexation equilibrium constants (log K...... became abundant at low pH. (3) Electrochemical reduction of chlorinated compounds using an SSI modified electrode. Here, the electrochemical reactivity of SSIs coated on indium tin oxide coated glass electrodes was investigated. Iron on the SSI modified electrode showed a typical Cyclic Voltammetry...

  9. A cascade of iron-containing proteins governs the genetic iron starvation response to promote iron uptake and inhibit iron storage in fission yeast.

    Directory of Open Access Journals (Sweden)

    Javier Encinar del Dedo

    2015-03-01

    Full Text Available Iron is an essential cofactor, but it is also toxic at high levels. In Schizosaccharomyces pombe, the sensor glutaredoxin Grx4 guides the activity of the repressors Php4 and Fep1 to mediate a complex transcriptional response to iron deprivation: activation of Php4 and inactivation of Fep1 leads to inhibition of iron usage/storage, and to promotion of iron import, respectively. However, the molecular events ruling the activity of this double-branched pathway remained elusive. We show here that Grx4 incorporates a glutathione-containing iron-sulfur cluster, alone or forming a heterodimer with the BolA-like protein Fra2. Our genetic study demonstrates that Grx4-Fra2, but not Fep1 nor Php4, participates not only in iron starvation signaling but also in iron-related aerobic metabolism. Iron-containing Grx4 binds and inactivates the Php4 repressor; upon iron deprivation, the cluster in Grx4 is probably disassembled, the proteins dissociate, and Php4 accumulates at the nucleus and represses iron consumption genes. Fep1 is also an iron-containing protein, and the tightly bound iron is required for transcriptional repression. Our data suggest that the cluster-containing Grx4-Fra2 heterodimer constitutively binds to Fep1, and upon iron deprivation the disassembly of the iron cluster between Grx4 and Fra2 promotes reverse metal transfer from Fep1 to Grx4-Fra2, and de-repression of iron-import genes. Our genetic and biochemical study demonstrates that the glutaredoxin Grx4 independently governs the Php4 and Fep1 repressors through metal transfer. Whereas iron loss from Grx4 seems to be sufficient to release Php4 and allow its nuclear accumulation, total or partial disassembly of the Grx4-Fra2 cluster actively participates in iron-containing Fep1 activation by sequestering its iron and decreasing its interaction with promoters.

  10. Computational Prediction and Analysis of Associations between Small Molecules and Binding-Associated S-Nitrosylation Sites.

    Science.gov (United States)

    Huang, Guohua; Li, Jincheng; Zhao, Chenglin

    2018-04-19

    Interactions between drugs and proteins occupy a central position during the process of drug discovery and development. Numerous methods have recently been developed for identifying drug⁻target interactions, but few have been devoted to finding interactions between post-translationally modified proteins and drugs. We presented a machine learning-based method for identifying associations between small molecules and binding-associated S-nitrosylated (SNO-) proteins. Namely, small molecules were encoded by molecular fingerprint, SNO-proteins were encoded by the information entropy-based method, and the random forest was used to train a classifier. Ten-fold and leave-one-out cross validations achieved, respectively, 0.7235 and 0.7490 of the area under a receiver operating characteristic curve. Computational analysis of similarity suggested that SNO-proteins associated with the same drug shared statistically significant similarity, and vice versa. This method and finding are useful to identify drug⁻SNO associations and further facilitate the discovery and development of SNO-associated drugs.

  11. Chemical speciation of iron in fog water

    Energy Technology Data Exchange (ETDEWEB)

    Schwanz, M.; Warneck, P. [Institut fuer Troposphaerenforschung e.V. (IfT), Leipzig (Germany); Preiss, M. [Frankfurt Univ. (Germany). Zentrum fuer Umweltforschung; Hoffmann, P. [TH Darmstadt, Fachbereich Materialwissenschaften (Germany)

    1998-02-01

    Concentrations of iron(II), iron(III), free sulfur(IV), manganese, copper, organic acids (acetate, formate, oxalate) and main anions and cations were determined in bulk and droplet size-fractionated samples of San Pietro Capofiume fog waters. The concentration of dissolved iron rose with decreasing droplet diameter, acidity and oxalate concentration increased as well. The distribution of iron among different complex-species was calculated. These calculations indicated that iron(III)-oxalato complexes were the dominant iron(III) species. Concentrations of dissolved manganese and copper were in the same concentration range as of dissolved iron, but the catalytic effects of these transition metals were not considered here. (orig.) 35 refs.

  12. Experimental Charge Density in an Oxidized Trinuclear Iron Complex using 15 K Synchrotron and 100 K Conventional Single-Crystal X-ray Diffraction

    International Nuclear Information System (INIS)

    Overgaard, J.; Larsen, F.; Timco, G.; Iversen, B.

    2009-01-01

    The experimental electron density distribution in a crystal consisting of the simplest conceivable trinuclear carboxylate-bridged iron-μ3-oxo dianion with two α-picolinium cations has been determined using both synchrotron (15 K) and conventional (100 K) X-ray diffraction data. The constituent trinuclear oxo-centered molecule consists of six 2-bridging formate groups between the iron pairs, while the axial ligand for all iron atoms is another formate group. The compound {(Fe3O(HCOO)6(HCOO)3)2-·H2O·2(α-CH3NC5H5)+}, ( 1) crystallizes in the monoclinic space group P21/m with charge assisted hydrogen bonds linking the α-picolinium cations to the trinuclear groups. The chemical bonding in the weakly asymmetric Fe3O-core of 1 has been examined through the use of the quantum theory of atoms in molecules, and in combination with experimental d-orbital populations, a significant electron sharing is observed between the Fe atoms and the central oxygen. The central oxygen exhibits clear sp2 hybridization, and the iron atoms have valence shell charge concentrations in all metal-ligand bond directions. The relative bond strengths are evaluated based upon the charge density distribution and found to be in accordance with the geometrical results. Integrated group charges follow expectations from formal chemical valences.

  13. Well-defined iron complexes as efficient catalysts for "green" atom-transfer radical polymerization of styrene, methyl methacrylate, and butyl acrylate with low catalyst loadings and catalyst recycling.

    Science.gov (United States)

    Nakanishi, So-Ichiro; Kawamura, Mitsunobu; Kai, Hidetomo; Jin, Ren-Hua; Sunada, Yusuke; Nagashima, Hideo

    2014-05-05

    Environmentally friendly iron(II) catalysts for atom-transfer radical polymerization (ATRP) were synthesized by careful selection of the nitrogen substituents of N,N,N-trialkylated-1,4,9-triazacyclononane (R3 TACN) ligands. Two types of structures were confirmed by crystallography: "[(R3 TACN)FeX2 ]" complexes with relatively small R groups have ionic and dinuclear structures including a [(R3 TACN)Fe(μ-X)3 Fe(R3 TACN)](+) moiety, whereas those with more bulky R groups are neutral and mononuclear. The twelve [(R3 TACN)FeX2 ]n complexes that were synthesized were subjected to bulk ATRP of styrene, methyl methacrylate (MMA), and butyl acrylate (BA). Among the iron complexes examined, [{(cyclopentyl)3 TACN}FeBr2 ] (4 b) was the best catalyst for the well-controlled ATRP of all three monomers. This species allowed easy catalyst separation and recycling, a lowering of the catalyst concentration needed for the reaction, and the absence of additional reducing reagents. The lowest catalyst loading was accomplished in the ATRP of MMA with 4 b (59 ppm of Fe based on the charged monomer). Catalyst recycling in ATRP with low catalyst loadings was also successful. The ATRP of styrene with 4 b (117 ppm Fe atom) was followed by precipitation from methanol to give polystyrene that contained residual iron below the calculated detection limit (0.28 ppm). Mechanisms that involve equilibria between the multinuclear and mononuclear species were also examined. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. An iron shuttle for deepwater silica in Late Archean and early Paleoproterozoic iron formation

    OpenAIRE

    Fischer, Woodward W.; Knoll, Andrew H.

    2009-01-01

    Iron formations are typically thinly bedded or laminated sedimentary rocks containing 15% or more of iron and a large proportion of silica (commonly > 40%). In the ca. 2590-2460 Ma Campbellrand-Kuruman Complex, Transvaal Supergroup, South Africa, iron formation occurs as a sediment-starved deepwater facies distal to carbonates and shales. Iron minerals, primarily siderite, define the lamination. The silica primarily occurs as thin beds and nodules of diagenetic chert (now microcrystalline qua...

  15. Accelerated dissolution of iron oxides in ice

    OpenAIRE

    D. Jeong; K. Kim; W. Choi

    2012-01-01

    Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a~new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4), the dissolution of iron oxides was greatly enhanced in the ice phas...

  16. Unusual Synthetic Pathway for an {Fe(NO)2}9 Dinitrosyl Iron Complex (DNIC) and Insight into DNIC Electronic Structure via Nuclear Resonance Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Speelman, Amy L.; Zhang, Bo; Silakov, Alexey; Skodje, Kelsey M.; Alp, E. Ercan; Zhao, Jiyong; Hu, Michael Y.; Kim, Eunsuk; Krebs, Karsten; Lehnert, Nicolai

    2016-06-06

    Dinitrosyl iron complexes (DNICs) are among the most abundant NO-derived cellular species. Monomeric DNICs can exist in the {Fe(NO)2}9 or {Fe(NO)2}10 oxidation state (in the Enemark -Feltham notation). However, experimental studies of analogous DNICs in both oxidation states are rare, which prevents a thorough understanding of the di ff erences in the electronic structures of these species. Here, the {Fe(NO)2}9 DNIC [Fe(dmp)(NO)2](OTf) ( 1 ; dmp = 2,9-dimethyl-1,10- phenanthroline) is synthesized from a ferrous precursor via an unusual pathway, involving disproportionation of an {FeNO}7 complex to yield the {Fe(NO)2}9 DNIC and a ferric species, which is subsequently reduced by NO gas to generate a ferrous complex that re-enters the reaction cycle. In contrast to most {Fe(NO)2}9 DNICs with neutral N-donor ligands, 1 exhibits high solution stability and can be characterized structurally and spectroscopically. Reduction of 1 yields the corresponding {Fe(NO)2}10 DNIC [Fe(dmp)(NO)2](2). The Mo ssbauer isomer shift of 2 is 0.08 mm/s smaller than that of 1 , which indicates that the iron center is slightly more oxidized in the reduced complex. The nuclear resonance vibrational spectra (NRVS) of 1 and 2 are distinct and provide direct experimental insight into di ff erences in bonding in these complexes. In particular, the symmetric out-of-plane Fe -N - O bending mode is shifted to higher energy by 188 cm-1 in 2 in comparison to 1 . Using quantum chemistry centered normal coordinate analysis (QCC-NCA), this is shown to arise from an increase in Fe - NO bond order and a sti ff ening of the Fe(NO)2 unit upon reduction of 1 to 2 . DFT calculations demonstrate that the changes in bonding arise from an iron- centered reduction which leads to a distinct increase in Fe - NO π -back-bonding in

  17. IRON DEPOSITIONS IN RAT LIVER AND SPLEEN WERE LOWER WHEN THE MINERAL WAS SUPPLIED AS A DERIVATIVE OF CASEIN HYDROLYSATE IN PLACE OF IRON SULFATE

    Directory of Open Access Journals (Sweden)

    A. A. MACHADO

    2009-01-01

    Full Text Available

    Iron derivatives from casein hydrolysate (Fe+3-peptide complex, are potential iron sources for biological applications. This study was conducted to evaluate rat liver and spleen iron deposition when administered Fe+3- peptide complex or iron sulfate, which was delivered via gavage for 28 days. Seventy rats (Hb 120g/L, divided into 7 groups (n=10, received a standard commercial diet containing 50 mg Fe/kg, supplemented by gastric gavage with daily doses (10, 30 and 60 mg Fe/kg body weight of iron peptide complex or iron sulfate for 4 weeks. The control group received Milli-Q water. Iron deposition in liver and spleen was determined qualitatively by histochemistry and quantitatively by atomic absorption spectrometry; lipid peroxidation was evaluated by the determination of thiobarbituric reactive substances. Iron deposition in liver was significantly reduced in groups supplemented with iron peptide complex when compared with the iron sulfate-supplemented groups (30 and 60 mg Fe/kg. A significant reduction of iron deposition in spleen was also shown in groups supplemented with iron-peptide complex (10 and 30 mg Fe/kg compared with iron sulfate, and 60 mg Fe/ kg, the levels of iron deposition were lower than in the control group. The results suggest that iron absorption could be better controlled when supplied as iron-peptide complex rather than of iron sulfate.

  18. S-Nitrosylation in Organs of Mice Exposed to Low or High Doses of γ-Rays: The Modulating Effect of Iodine Contrast Agent at a Low Radiation Dose

    Directory of Open Access Journals (Sweden)

    Fadia Nicolas

    2015-04-01

    Full Text Available The covalent addition of nitric oxide (NO• onto cysteine thiols, or S-nitrosylation, modulates the activity of key signaling proteins. The dysregulation of normal S-nitrosylation contributes to degenerative conditions and to cancer. To gain insight into the biochemical changes induced by low-dose ionizing radiation, we determined global S-nitrosylation by the “biotin switch” assay coupled with mass spectrometry analyses in organs of C57BL/6J mice exposed to acute 0.1 Gy of 137Cs γ-rays. The dose of radiation was delivered to the whole body in the presence or absence of iopamidol, an iodinated contrast agent used during radiological examinations. To investigate whether similar or distinct nitrosylation patterns are induced following high-dose irradiation, mice were exposed in parallel to acute 4 Gy of 137Cs g rays. Analysis of modulated S-nitrosothiols (SNO-proteins in freshly-harvested organs of animals sacrificed 13 days after irradiation revealed radiation dose- and contrast agent-dependent changes. The major results were as follows: (i iopamidol alone had significant effects on S-nitrosylation in brain, lung and liver; (ii relative to the control, exposure to 0.1 Gy without iopamidol resulted in statistically-significant SNO changes in proteins that differ in molecular weight in liver, lung, brain and blood plasma; (iii iopamidol enhanced the decrease in S-nitrosylation induced by 0.1 Gy in brain; (iv whereas a decrease in S-nitrosylation occurred at 0.1 Gy for proteins of ~50 kDa in brain and for proteins of ~37 kDa in liver, an increase was detected at 4 Gy in both organs; (v mass spectrometry analyses of nitrosylated proteins in brain revealed differential modulation of SNO proteins (e.g., sodium/potassium-transporting ATPase subunit beta-1; beta tubulins; ADP-ribosylation factor 5 by low- and high-dose irradiation; and (vi ingenuity pathway analysis identified major signaling networks to be modulated, in particular the neuronal

  19. Hydride Attack on a Coordinated Ferric Nitrosyl: Experimental and DFT Evidence for the Formation of a Heme Model-HNO Derivative

    Science.gov (United States)

    Abucayon, Erwin G.; Khade, Rahul L.; Powell, Douglas R.; Zhang, Yong; Richter-Addo, George B.

    2016-01-01

    Heme-HNO species are crucial intermediates in several biological processes. To date, no well-defined Fe heme-HNO model compounds have been reported. Hydride attack on the cationic ferric [(OEP)Fe(NO)(5-MeIm)]OTf (OEP = octaethylporphy-rinato dianion) generates the Fe-HNO product that has been characterized by IR and 1H NMR spectroscopy. Results of DFT calculations reveal a direct attack of the hydride on the N atom of the coordinated ferric nitrosyl. PMID:26678216

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron in your body causes iron-deficiency anemia. Lack of iron usually is due to blood loss, ... can help prevent overdosing in children. Because recent research supports concerns that iron deficiency during infancy and ...

  1. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, eggs, ... is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and iron- ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... absorb iron from the gastrointestinal tract (GI tract). Blood loss When you lose blood, you lose iron. ... other conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To ...

  3. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other dark ... of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other dark ...

  4. Iron-Deficiency Anemia

    Science.gov (United States)

    ... Home / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español ... bleeding Consuming less than recommended daily amounts of iron Iron-deficiency anemia can be caused by getting ...

  5. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... drawings also can cause iron-deficiency anemia. Poor Diet The best sources of iron are meat, poultry, ... more likely to develop iron-deficiency anemia. Vegetarian diets can provide enough iron if you eat the ...

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... you are diagnosed with iron-deficiency anemia. Risk Factors You may have an increased risk for iron- ... iron-deficiency anemia if you have certain risk factors , including pregnancy. To prevent iron-deficiency anemia, your ...

  7. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... The best sources of iron are meat, poultry, fish, and iron-fortified foods (foods that have iron ... you: Follow a diet that excludes meat and fish, which are the best sources of iron. However, ...

  8. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... good nonmeat sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach ... good nonmeat sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach ...

  9. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... to moderate iron-deficiency anemia, or red blood cell transfusion for severe iron-deficiency anemia. You may ... body needs iron to make healthy red blood cells. Iron-deficiency anemia usually develops over time because ...

  10. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... from developing iron-deficiency anemia. Foods that are good sources of iron include dried beans, dried fruits, ... iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... re more likely to develop iron-deficiency anemia. Vegetarian diets can provide enough iron if you eat ... which are the best sources of iron. However, vegetarian diets can provide enough iron if you eat ...

  12. Iron-Deficiency Anemia

    Science.gov (United States)

    ... re more likely to develop iron-deficiency anemia. Vegetarian diets can provide enough iron if you eat ... which are the best sources of iron. However, vegetarian diets can provide enough iron if you eat ...

  13. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... can provide enough iron if you eat the right foods. For example, good nonmeat sources of iron ... can provide enough iron if you eat the right foods. For example, good nonmeat sources of iron ...

  14. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-deficiency anemia may require treatment in a hospital, blood transfusions , iron injections, or intravenous iron therapy. ... Treatment may need to be done in a hospital. The goals of treating iron-deficiency anemia are ...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... develop new therapies for conditions that affect the balance of iron in the body and lead to ... Disease Control and Prevention) Iron - Health Professional Fact Sheet (NIH) Iron Dietary Supplement Fact Sheet (NIH) Iron- ...

  16. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... pregnancy. Good sources of iron are meat, poultry, fish, and iron-fortified foods that have iron added. Vegetarian diets can provide enough iron if you choose nonmeat sources ...

  17. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other ... sources of iron include iron-fortified breads and cereals, beans, tofu, dried fruits, and spinach and other ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... enough iron-rich foods, such as meat and fish, may result in you getting less than the ... pregnancy. Good sources of iron are meat, poultry, fish, and iron-fortified foods that have iron added. ...

  19. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... iron-rich foods, especially during certain stages of life when more iron is needed, such as childhood and pregnancy. Good sources of iron are meat, poultry, fish, and iron- ...

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... for your body to absorb iron from the gastrointestinal tract (GI tract). Blood loss When you lose blood, ... iron deficiency. Endurance athletes lose iron through their gastrointestinal tracts. They also lose iron through the breakdown of ...

  1. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  2. Electronic phase diagrams and competing ground states of complex iron pnictides and chalcogenides. A Moessbauer spectroscopy and muon spin rotation/relaxation study

    Energy Technology Data Exchange (ETDEWEB)

    Kamusella, Sirko

    2017-03-01

    In this thesis the superconducting and magnetic phases of LiOH(Fe,Co)(Se,S), CuFeAs/CuFeSb, and LaFeP{sub 1-x}As{sub x}O - belonging to the 11, 111 and 1111 structural classes of iron-based arsenides and chalcogenides - are investigated by means of {sup 57}Fe Moessbauer spectroscopy and muon spin rotation/relaxation (μSR). Of major importance in this study is the application of high magnetic fields in Moessbauer spectroscopy to distinguish and characterize ferro- (FM) and antiferromagnetic (AFM) order. A user-friendly Moessbauer data analysis program was developed to provide suitable model functions not only for high field spectra, but relaxation spectra or parameter distributions in general. In LaFeP{sub 1-x}As{sub x}O the reconstruction of the Fermi surface is described by the vanishing of the Γ hole pocket with decreasing x. The continuous change of the orbital character and the covalency of the d-electrons is shown by Moessbauer spectroscopy. A novel antiferromagnetic phase with small magnetic moments of ∼ 0.1 μ{sub B} state is characterized. The superconducting order parameter is proven to continuously change from a nodal to a fully gapped s-wave like Fermi surface in the superconducting regime as a function of x, partially investigated on (O,F) substituted samples. LiOHFeSe is one of the novel intercalated FeSe compounds, showing strongly increased T{sub C} = 43 K mainly due to increased interlayer spacing and resulting two-dimensionality of the Fermi surface. The primary interest of the samples of this thesis is the simultaneously observed ferromagnetism and superconductivity. The local probe techniques prove that superconducting sample volume gets replaced by ferromagnetic volume. Ferromagnetism arises from magnetic order with T{sub C} = 10 K of secondary iron in the interlayer. The tendency of this system to show (Li,Fe) disorder is preserved upon (Se,S) substitution. However, superconductivity gets suppressed. The results of Moessbauer spectroscopy

  3. Colour Metallography of Cast Iron - White Cast Iron (Ⅱ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2011-11-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  4. Colour Metallography of Cast Iron - Chapter 2: Grey Iron (Ⅱ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2009-08-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  5. Effect of sodium nitrite on ischaemia and reperfusion-induced arrhythmias in anaesthetized dogs: is protein S-nitrosylation involved?

    Directory of Open Access Journals (Sweden)

    Mária Kovács

    Full Text Available To provide evidence for the protective role of inorganic nitrite against acute ischaemia and reperfusion-induced ventricular arrhythmias in a large animal model.Dogs, anaesthetized with chloralose and urethane, were administered intravenously with sodium nitrite (0.2 µmol kg(-1 min(-1 in two protocols. In protocol 1 nitrite was infused 10 min prior to and during a 25 min occlusion of the left anterior descending (LAD coronary artery (NaNO2-PO; n = 14, whereas in protocol 2 the infusion was started 10 min prior to reperfusion of the occluded vessel (NaNO2-PR; n = 12. Control dogs (n = 15 were infused with saline and subjected to the same period of ischaemia and reperfusion. Severities of ischaemia and ventricular arrhythmias, as well as changes in plasma nitrate/nitrite (NOx levels in the coronary sinus blood, were assessed throughout the experiment. Myocardial superoxide and nitrotyrosine (NT levels were determined during reperfusion. Changes in protein S-nitrosylation (SNO and S-glutathionylation were also examined.Compared with controls, sodium nitrite administered either pre-occlusion or pre-reperfusion markedly suppressed the number and severity of ventricular arrhythmias during occlusion and increased survival (0% vs. 50 and 92% upon reperfusion. There were also significant decreases in superoxide and NT levels in the nitrite treated dogs. Compared with controls, increased SNO was found only in NaNO2-PR dogs, whereas S-glutathionylation occurred primarily in NaNO2-PO dogs.Intravenous infusion of nitrite profoundly reduced the severity of ventricular arrhythmias resulting from acute ischaemia and reperfusion in anaesthetized dogs. This effect, among several others, may result from an NO-mediated reduction in oxidative stress, perhaps through protein SNO and/or S-glutathionylation.

  6. 2,4-Dichlorophenoxyacetic acid promotes S-nitrosylation and oxidation of actin affecting cytoskeleton and peroxisomal dynamics.

    Science.gov (United States)

    Rodríguez-Serrano, M; Pazmiño, D M; Sparkes, I; Rochetti, A; Hawes, C; Romero-Puertas, M C; Sandalio, L M

    2014-09-01

    2,4-Dichlorophenoxyacetic acid (2,4-D) is a synthetic auxin used as a herbicide to control weeds in agriculture. A high concentration of 2,4-D promotes leaf epinasty and cell death. In this work, the molecular mechanisms involved in the toxicity of this herbicide are studied by analysing in Arabidopsis plants the accumulation of reactive oxygen species (ROS) and nitric oxide (NO), and their effect on cytoskeleton structure and peroxisome dynamics. 2,4-D (23 mM) promotes leaf epinasty, whereas this process was prevented by EDTA, which can reduce ·OH accumulation. The analysis of ROS accumulation by confocal microscopy showed a 2,4-D-dependent increase in both H2O2 and O2·(-), whereas total NO was not affected by the treatment. The herbicide promotes disturbances on the actin cytoskeleton structure as a result of post-translational modification of actin by oxidation and S-nitrosylation, which could disturb actin polymerization, as suggested by the reduction of the F-actin/G-actin ratio. These effects were reduced by EDTA, and the reduction of ROS production in Arabidopsis mutants deficient in xanthine dehydrogenase (Atxdh) gave rise to a reduction in actin oxidation. Also, 2,4-D alters the dynamics of the peroxisome, slowing the speed and shortening the distances by which these organelles are displaced. It is concluded that 2,4-D promotes oxidative and nitrosative stress, causing disturbances in the actin cytoskeleton, thereby affecting the dynamics of peroxisomes and some other organelles such as the mitochondria, with xanthine dehydrogenase being involved in ROS production under these conditions. These structural changes in turn appear to be responsible for the leaf epinasty. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  7. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Research Home / < Back To Health Topics / Iron-Deficiency Anemia Iron-Deficiency Anemia Also known as Leer en español Iron-deficiency ... iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen for iron-deficiency anemia, your doctor ...

  8. An Odd-Electron Complex [Ru-k(NOm)(Q(n))(terpy)](2+) with Two Prototypical Non-Innocent Ligands

    Czech Academy of Sciences Publication Activity Database

    Das, A. K.; Sarkar, B.; Duboc, C.; Strobel, S.; Fiedler, Jan; Záliš, Stanislav; Lahiri, G. K.; Kaim, W.

    2009-01-01

    Roč. 48, č. 23 (2009), s. 4242-4245 ISSN 1433-7851 R&D Projects: GA AV ČR KAN100400702; GA MŠk OC 139 Institutional research plan: CEZ:AV0Z40400503 Keywords : nitrosyl complexes * non-innocent ligands * quinones * radical ligands * ruthenium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 11.829, year: 2009

  9. Iron Biofortification of Modern Wheat Cultivar

    DEFF Research Database (Denmark)

    Shirvanehdeh, Behrooz Darbani; Brinch-Pedersen, Henrik; Tauris, Birgitte

    2011-01-01

    Iron deficiency anemia (IDA) is a public health problem and is primarily due to poverty in the developing world which leads to a simple, undiversified diet that largely is based on stables, such as wheat and rice. One of the key targets in the international alliance HarvestPlus is to boost the iron...... content of these stables to improve the living conditions of the poor people. As member of HarvestPlus we are working to improve the iron content quanti- and qualitatively in the wheat grain. Therefore, wheat grain has been subjected to work through endosperm-specific expression of the ferritin protein...... as an iron storage complex. Primary evaluation of Bobwhite cv. has approved that endosperm expression of wheat’s own ferritin, works as a sink for iron and accumulates two to three folds more iron in the endosperm. To bring the bioavailable iron on the people's tables, modern cultivars were applied for co...

  10. IRON DOME

    African Journals Online (AJOL)

    Automated precise guided missile defence has been around for some years, and is a modern-day mechanism used frequently since 2011 to defend against rocket attacks penetrating national airspace. Israel's automated Iron Dome. Missile Defence System has intercepted over 1 000 rockets during two recent.

  11. Colour Metallography of Cast Iron

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2009-05-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron.Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron , uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditionalmaterials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  12. Iron and iron derived radicals

    International Nuclear Information System (INIS)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fast! Think small! In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab

  13. Iron bioavailability from commercially available iron supplements.

    Science.gov (United States)

    Christides, Tatiana; Wray, David; McBride, Richard; Fairweather, Rose; Sharp, Paul

    2015-12-01

    Iron deficiency anaemia (IDA) is a global public health problem. Treatment with the standard of care ferrous iron salts may be poorly tolerated, leading to non-compliance and ineffective correction of IDA. Employing supplements with higher bioavailability might permit lower doses of iron to be used with fewer side effects, thus improving treatment efficacy. Here, we compared the iron bioavailability of ferrous sulphate tablets with alternative commercial iron products, including three liquid-based supplements. Iron bioavailability was measured using Caco-2 cells with ferritin formation as a surrogate marker for iron uptake. Statistical analysis was performed using one-way ANOVA followed by either Dunnett's or Tukey's multiple comparisons tests. Spatone Apple(®) (a naturally iron-rich mineral water with added ascorbate) and Iron Vital F(®) (a synthetic liquid iron supplement) had the highest iron bioavailability. There was no statistical difference between iron uptake from ferrous sulphate tablets, Spatone(®) (naturally iron-rich mineral water alone) and Pregnacare Original(®) (a multimineral/multivitamin tablet). In our in vitro model, naturally iron-rich mineral waters and synthetic liquid iron formulations have equivalent or better bioavailability compared with ferrous iron sulphate tablets. If these results are confirmed in vivo, this would mean that at-risk groups of IDA could be offered a greater choice of more bioavailable and potentially better tolerated iron preparations.

  14. Certain Metal Ions are Inhibitors of Cytochrome b (6) f Complex 'Rieske' Iron-Sulfur Protein Domain Movements

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Arthur G.; Bowman, Michael K.; Kramer, David M.

    2002-03-26

    1Abbreviations: cyt, cytochrome; cyt bL, low potential b cytochrome; cyt bH, high potential b cytochrome; DBMIB, 2,5-dibromo-3-methyl-6-isopropylbenzoquinone; DMSO, dimethylsulfoxide; DNP-INT, 2'-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenylether; EPR, electron paramagnetic resonance; HEPES, n-(2-hydroxyethyl)piperazine-n'-(2-ethanesulfonic acid); NQNO, 2-nonyl-4-hydroxyquinoline n-oxide; ISP, iron-sulfur protein; MOA, E-b-methoxyacrylate; pmf, proton motive force; PC, plastocyanin; PQ, plastoquinone; PQH2, plastoquinol; PS, photosystem; Qi, quinol reductase; Qo, quinol oxidase; UHDBT, 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole.

  15. Effects of divalent amino acids on iron absorption

    International Nuclear Information System (INIS)

    Christensen, J.M.; Ghannam, M.; Ayres, J.W.

    1984-01-01

    Solutions of each of 10 amino acids or ascorbic acid were mixed with iron and orally administered to rats. Iron was absorbed to a statistically significantly greater extent when mixed with asparagine, glycine, serine, or ascorbic acid as compared with a control solution of iron. The largest effects were for asparagine and glycine, which also increased iron absorption to a significantly greater extent than did serine or ascorbic acid. No statistically significant increase in iron absorption occurred when any of the other amino acids was mixed with iron. The extent of iron absorption from each test solution, as measured by area under the concentration of iron-59 in the blood-time curve (r2 . 0.0002), and the initial rate of iron absorption for each test solution (r2 . 0.01) showed no correlation with the stability constant of the amino acid-iron complex

  16. Immunity to plant pathogens and iron homeostasis.

    Science.gov (United States)

    Aznar, Aude; Chen, Nicolas W G; Thomine, Sebastien; Dellagi, Alia

    2015-11-01

    Iron is essential for metabolic processes in most living organisms. Pathogens and their hosts often compete for the acquisition of this nutrient. However, iron can catalyze the formation of deleterious reactive oxygen species. Hosts may use iron to increase local oxidative stress in defense responses against pathogens. Due to this duality, iron plays a complex role in plant-pathogen interactions. Plant defenses against pathogens and plant response to iron deficiency share several features, such as secretion of phenolic compounds, and use common hormone signaling pathways. Moreover, fine tuning of iron localization during infection involves genes coding iron transport and iron storage proteins, which have been shown to contribute to immunity. The influence of the plant iron status on the outcome of a given pathogen attack is strongly dependent on the nature of the pathogen infection strategy and on the host species. Microbial siderophores emerged as important factors as they have the ability to trigger plant defense responses. Depending on the plant species, siderophore perception can be mediated by their strong iron scavenging capacity or possibly via specific recognition as pathogen associated molecular patterns. This review highlights that iron has a key role in several plant-pathogen interactions by modulating immunity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. The Iron Age Today

    Directory of Open Access Journals (Sweden)

    Harold Mytum

    2018-02-01

    Full Text Available Thanks to investment in walking the landscape, aerial photography, geophysical survey and excavation, there is a baseline of information on the distribution and types of enclosed settlement and examples of high-quality site-based data, often revealing complex site histories. These are our resources from which to extract meaning about the past — but what can actually be said about the Iron Age from all these data? What are the next stages in moving towards greater understanding? And what is the current management and presentation of the Iron Age to the public in Wales? This contribution reviews our current state of knowledge and its uses so that we can develop strategies to improve the data and communicate what it can tell us about the Welsh past.

  18. Iron and stony-iron meteorites

    DEFF Research Database (Denmark)

    Ruzicka, Alex M.; Haack, Henning; Chabot, Nancy L.

    2017-01-01

    By far most of the melted and differentiated planetesimals that have been sampled as meteorites are metal-rich iron meteorites or stony iron meteorites. The parent asteroids of these meteorites accreted early and differentiated shortly after the solar system formed, producing some of the oldest...... and interpretations for iron and stony iron meteorites (Plate 13.1). Such meteorites provide important constraints on the nature of metal-silicate separation and mixing in planetesimals undergoing partial to complete differentiation. They include iron meteorites that formed by the solidification of cores...... (fractionally crystallized irons), irons in which partly molten metal and silicates of diverse types were mixed together (silicate-bearing irons), stony irons in which partly molten metal and olivine from cores and mantles were mixed together (pallasites), and stony irons in which partly molten metal...

  19. Dystrophin Threshold Level Necessary for Normalization of Neuronal Nitric Oxide Synthase, Inducible Nitric Oxide Synthase, and Ryanodine Receptor-Calcium Release Channel Type 1 Nitrosylation in Golden Retriever Muscular Dystrophy Dystrophinopathy.

    Science.gov (United States)

    Gentil, Christel; Le Guiner, Caroline; Falcone, Sestina; Hogrel, Jean-Yves; Peccate, Cécile; Lorain, Stéphanie; Benkhelifa-Ziyyat, Sofia; Guigand, Lydie; Montus, Marie; Servais, Laurent; Voit, Thomas; Piétri-Rouxel, France

    2016-09-01

    At present, the clinically most advanced strategy to treat Duchenne muscular dystrophy (DMD) is the exon-skipping strategy. Whereas antisense oligonucleotide-based clinical trials are underway for DMD, it is essential to determine the dystrophin restoration threshold needed to ensure improvement of muscle physiology at the molecular level. A preclinical trial has been conducted in golden retriever muscular dystrophy (GRMD) dogs treated in a forelimb by locoregional delivery of rAAV8-U7snRNA to promote exon skipping on the canine dystrophin messenger. Here, we exploited rAAV8-U7snRNA-transduced GRMD muscle samples, well characterized for their percentage of dystrophin-positive fibers, with the aim of defining the threshold of dystrophin rescue necessary for normalization of the status of neuronal nitric oxide synthase mu (nNOSμ), inducible nitric oxide synthase (iNOS), and ryanodine receptor-calcium release channel type 1 (RyR1), crucial actors for efficient contractile function. Results showed that restoration of dystrophin in 40% of muscle fibers is needed to decrease abnormal cytosolic nNOSμ expression and to reduce overexpression of iNOS, these two parameters leading to a reduction in the NO level in the muscle fibers. Furthermore, the same percentage of dystrophin-positive fibers of 40% was associated with the normalization of RyR1 nitrosylation status and with stabilization of the RyR1-calstabin1 complex that is required to facilitate coupled gating. We concluded that a minimal threshold of 40% of dystrophin-positive fibers is necessary for the reinstatement of central proteins needed for proper muscle contractile function, and thus identified a rate of dystrophin expression significantly improving, at the molecular level, the dystrophic muscle physiology.

  20. A Six-Coordinate Peroxynitrite Low-Spin Iron(III) Porphyrinate Complex-The Product of the Reaction of Nitrogen Monoxide (·NO(g)) with a Ferric-Superoxide Species.

    Science.gov (United States)

    Sharma, Savita K; Schaefer, Andrew W; Lim, Hyeongtaek; Matsumura, Hirotoshi; Moënne-Loccoz, Pierre; Hedman, Britt; Hodgson, Keith O; Solomon, Edward I; Karlin, Kenneth D

    2017-12-06

    Peroxynitrite ( - OON═O, PN) is a reactive nitrogen species (RNS) which can effect deleterious nitrative or oxidative (bio)chemistry. It may derive from reaction of superoxide anion (O 2 •- ) with nitric oxide (·NO) and has been suggested to form an as-yet unobserved bound heme-iron-PN intermediate in the catalytic cycle of nitric oxide dioxygenase (NOD) enzymes, which facilitate a ·NO homeostatic process, i.e., its oxidation to the nitrate anion. Here, a discrete six-coordinate low-spin porphyrinate-Fe III complex [(P Im )Fe III ( - OON═O)] (3) (P Im ; a porphyrin moiety with a covalently tethered imidazole axial "base" donor ligand) has been identified and characterized by various spectroscopies (UV-vis, NMR, EPR, XAS, resonance Raman) and DFT calculations, following its formation at -80 °C by addition of ·NO (g) to the heme-superoxo species, [(P Im )Fe III (O 2 •- )] (2). DFT calculations confirm that 3 is a six-coordinate low-spin species with the PN ligand coordinated to iron via its terminal peroxidic anionic O atom with the overall geometry being in a cis-configuration. Complex 3 thermally transforms to its isomeric low-spin nitrato form [(P Im )Fe III (NO 3 - )] (4a). While previous (bio)chemical studies show that phenolic substrates undergo nitration in the presence of PN or PN-metal complexes, in the present system, addition of 2,4-di-tert-butylphenol ( 2,4 DTBP) to complex 3 does not lead to nitrated phenol; the nitrate complex 4a still forms. DFT calculations reveal that the phenolic H atom approaches the terminal PN O atom (farthest from the metal center and ring core), effecting O-O cleavage, giving nitrogen dioxide (·NO 2 ) plus a ferryl compound [(P Im )Fe IV ═O] (7); this rebounds to give [(P Im )Fe III (NO 3 - )] (4a).The generation and characterization of the long sought after ferriheme peroxynitrite complex has been accomplished.