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Sample records for respiratory complex iii

  1. Quantum Calculations of Electron Tunneling in Respiratory Complex III.

    PubMed

    Hagras, Muhammad A; Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

    2015-11-19

    The most detailed and comprehensive to date study of electron transfer reactions in the respiratory complex III of aerobic cells, also known as bc1 complex, is reported. In the framework of the tunneling current theory, electron tunneling rates and atomistic tunneling pathways between different redox centers were investigated for all electron transfer reactions comprising different stages of the proton-motive Q-cycle. The calculations reveal that complex III is a smart nanomachine, which under certain conditions undergoes conformational changes gating electron transfer, or channeling electrons to specific pathways. One-electron tunneling approximation was adopted in the tunneling calculations, which were performed using hybrid Broken-Symmetry (BS) unrestricted DFT/ZINDO levels of theory. The tunneling orbitals were determined using an exact biorthogonalization scheme that uniquely separates pairs of tunneling orbitals with small overlaps out of the remaining Franck-Condon orbitals with significant overlap. Electron transfer rates in different redox pairs show exponential distance dependence, in agreement with the reported experimental data; some reactions involve coupled proton transfer. Proper treatment of a concerted two-electron bifurcated tunneling reaction at the Q(o) site is given.

  2. Renal Tubular Mitochondrial Abnormalities in Complex II/III Respiratory Chain Deficiency.

    PubMed

    France, Joel; Ashoor, Isa; Craver, Randall

    2017-06-01

    Defects in the respiratory chain may present with a wide spectrum of clinical signs and symptoms. In this "Images in Pathology" discussion we correlate the clinical, histologic, and ultrastructural findings in a 12-year-old male with a complex II/III respiratory chain deficiency and kidney dysfunction.

  3. Cardiolipin-dependent reconstitution of respiratory supercomplexes from purified Saccharomyces cerevisiae complexes III and IV.

    PubMed

    Bazán, Soledad; Mileykovskaya, Eugenia; Mallampalli, Venkata K P S; Heacock, Philip; Sparagna, Genevieve C; Dowhan, William

    2013-01-04

    Here, we report for the first time in vitro reconstitution of the respiratory supercomplexes from individual complexes III and IV. Complexes III and IV were purified from Saccharomyces cerevisiae mitochondria. Complex III contained eight molecules of cardiolipin, and complex IV contained two molecules of cardiolipin, as determined by electrospray ionization-mass spectrometry. Complex IV also contained Rcf1p. No supercomplexes were formed upon mixing of the purified complexes, and low amounts of the supercomplex trimer III(2)IV(1) were formed after reconstitution into proteoliposomes containing only phosphatidylcholine and phosphatidylethanolamine. Further addition of cardiolipin to the proteoliposome reconstitution mixture resulted in distinct formation of both the III(2)IV(1) supercomplex trimer and III(2)IV(2) supercomplex tetramer. No other anionic phospholipid was as effective as cardiolipin in supporting tetramer formation. Phospholipase treatment of complex IV prevented trimer formation in the absence of cardiolipin. Both trimer and tetramer formations were restored by cardiolipin. Analysis of the reconstituted tetramer by single particle electron microscopy confirmed native organization of individual complexes within the supercomplex. In conclusion, although some trimer formation occurred dependent only on tightly bound cardiolipin, tetramer formation required additional cardiolipin. This is consistent with the high cardiolipin content in the native tetramer. The dependence on cardiolipin for supercomplex formation suggests that changes in cardiolipin levels resulting from changes in physiological conditions may control the equilibrium between individual respiratory complexes and supercomplexes in vivo.

  4. Internal switches modulating electron tunneling currents in respiratory complex III.

    PubMed

    Hagras, Muhammad A; Stuchebrukhov, Alexei A

    2016-06-01

    In different X-ray crystal structures of bc1 complex, some of the key residues of electron tunneling pathways are observed in different conformations; here we examine their relative importance in modulating electron transfer and propose their possible gating function in the Q-cycle. The study includes inter-monomeric electron transfer; here we provide atomistic details of the reaction, and discuss the possible roles of inter-monomeric electronic communication in bc(1) complex. Binding of natural ligands or inhibitors leads to local conformational changes which propagate through protein and control the conformation of key residues involved in the electron tunneling pathways. Aromatic-aromatic interactions are highly utilized in the communication network since the key residues are aromatic in nature. The calculations show that there is a substantial change of the electron transfer rates between different redox pairs depending on the different conformations acquired by the key residues of the complex.

  5. Severe respiratory complex III defect prevents liver adaptation to prolonged fasting.

    PubMed

    Kremer, Laura S; L'hermitte-Stead, Caroline; Lesimple, Pierre; Gilleron, Mylène; Filaut, Sandrine; Jardel, Claude; Haack, Tobias B; Strom, Tim M; Meitinger, Thomas; Azzouz, Hatem; Tebib, Neji; Ogier de Baulny, Hélène; Touati, Guy; Prokisch, Holger; Lombès, Anne

    2016-08-01

    Next generation sequencing approaches have tremendously improved the diagnosis of rare genetic diseases. It may however be faced with difficult clinical interpretation of variants. Inherited enzymatic diseases provide an invaluable possibility to evaluate the function of the defective enzyme in human cell biology. This is the case for respiratory complex III, which has 11 structural subunits and requires several assembly factors. An important role of complex III in liver function is suggested by its frequent impairment in human cases of genetic complex III defects. We report the case of a child with complex III defect and acute liver dysfunction with lactic acidosis, hypoglycemia, and hyperammonemia. Mitochondrial activities were assessed in liver and fibroblasts using spectrophotometric assays. Genetic analysis was done by exome followed by Sanger sequencing. Functional complementation of defective fibroblasts was performed using lentiviral transduction followed by enzymatic analyses and expression assays. Homozygous, truncating, mutations in LYRM7 and MTO1, two genes encoding essential mitochondrial proteins were found. Functional complementation of the complex III defect in fibroblasts demonstrated the causal role of LYRM7 mutations. Comparison of the patient's clinical history to previously reported patients with complex III defect due to nuclear DNA mutations, some actually followed by us, showed striking similarities allowing us to propose common pathophysiology. Profound complex III defect in liver does not induce actual liver failure but impedes liver adaptation to prolonged fasting leading to severe lactic acidosis, hypoglycemia, and hyperammonemia, potentially leading to irreversible brain damage. The diagnosis of rare genetic disease has been tremendously accelerated by the development of high throughput sequencing technology. In this paper we report the investigations that have led to identify LYRM7 mutations causing severe hepatic defect of respiratory

  6. Assembly of respiratory complexes I, III, and IV into NADH oxidase supercomplex stabilizes complex I in Paracoccus denitrificans.

    PubMed

    Stroh, Anke; Anderka, Oliver; Pfeiffer, Kathy; Yagi, Takao; Finel, Moshe; Ludwig, Bernd; Schägger, Hermann

    2004-02-06

    Stable supercomplexes of bacterial respiratory chain complexes III (ubiquinol:cytochrome c oxidoreductase) and IV (cytochrome c oxidase) have been isolated as early as 1985 (Berry, E. A., and Trumpower, B. L. (1985) J. Biol. Chem. 260, 2458-2467). However, these assemblies did not comprise complex I (NADH:ubiquinone oxidoreductase). Using the mild detergent digitonin for solubilization of Paracoccus denitrificans membranes we could isolate NADH oxidase, assembled from complexes I, III, and IV in a 1:4:4 stoichiometry. This is the first chromatographic isolation of a complete "respirasome." Inactivation of the gene for tightly bound cytochrome c552 did not prevent formation of this supercomplex, indicating that this electron carrier protein is not essential for structurally linking complexes III and IV. Complex I activity was also found in the membranes of mutant strains lacking complexes III or IV. However, no assembled complex I but only dissociated subunits were observed following the same protocols used for electrophoretic separation or chromatographic isolation of the supercomplex from the wild-type strain. This indicates that the P. denitrificans complex I is stabilized by assembly into the NADH oxidase supercomplex. In addition to substrate channeling, structural stabilization of a membrane protein complex thus appears as one of the major functions of respiratory chain supercomplexes.

  7. Thiol-based antioxidants elicit mitochondrial oxidation via respiratory complex III

    PubMed Central

    Beaudoin, Jessica N.; Ponnuraj, Nagendraprabhu; DiLiberto, Stephen J.; Hanafin, William P.; Kenis, Paul J. A.; Gaskins, H. Rex

    2015-01-01

    Excessive oxidation is widely accepted as a precursor to deleterious cellular function. On the other hand, an awareness of the role of reductive stress as a similar pathological insult is emerging. Here we report early dynamic changes in compartmentalized glutathione (GSH) redox potentials in living cells in response to exogenously supplied thiol-based antioxidants. Noninvasive monitoring of intracellular thiol-disulfide exchange via a genetically encoded biosensor targeted to cytosol and mitochondria revealed unexpectedly rapid oxidation of the mitochondrial matrix in response to GSH ethyl ester or N-acetyl-l-cysteine. Oxidation of the probe occurred within seconds in a concentration-dependent manner and was attenuated with the membrane-permeable ROS scavenger tiron. In contrast, the cytosolic sensor did not respond to similar treatments. Surprisingly, the immediate mitochondrial oxidation was not abrogated by depolarization of mitochondrial membrane potential or inhibition of mitochondrial GSH uptake. After detection of elevated levels of mitochondrial ROS, we systematically inhibited multisubunit protein complexes of the mitochondrial respiratory chain and determined that respiratory complex III is a downstream target of thiol-based compounds. Disabling complex III with myxothiazol completely blocked matrix oxidation induced with GSH ethyl ester or N-acetyl-l-cysteine. Our findings provide new evidence of a functional link between exogenous thiol-containing antioxidants and mitochondrial respiration. PMID:25994788

  8. Tafenoquine, an antiplasmodial 8-aminoquinoline, targets leishmania respiratory complex III and induces apoptosis.

    PubMed

    Carvalho, Luis; Luque-Ortega, Juan Román; Manzano, José Ignacio; Castanys, Santiago; Rivas, Luis; Gamarro, Francisco

    2010-12-01

    Tafenoquine (TFQ), an 8-aminoquinoline analogue of primaquine, which is currently under clinical trial (phase IIb/III) for the treatment and prevention of malaria, may represent an alternative treatment for leishmaniasis. In this work, we have studied the mechanism of action of TFQ against Leishmania parasites. TFQ impaired the overall bioenergetic metabolism of Leishmania promastigotes, causing a rapid drop in intracellular ATP levels without affecting plasma membrane permeability. TFQ induced mitochondrial dysfunction through the inhibition of cytochrome c reductase (respiratory complex III) with a decrease in the oxygen consumption rate and depolarization of mitochondrial membrane potential. This was accompanied by ROS production, elevation of intracellular Ca(2+) levels and concomitant nuclear DNA fragmentation. We conclude that TFQ targets Leishmania mitochondria, leading to an apoptosis-like death process.

  9. Tafenoquine, an Antiplasmodial 8-Aminoquinoline, Targets Leishmania Respiratory Complex III and Induces Apoptosis ▿

    PubMed Central

    Carvalho, Luis; Luque-Ortega, Juan Román; Manzano, José Ignacio; Castanys, Santiago; Rivas, Luis; Gamarro, Francisco

    2010-01-01

    Tafenoquine (TFQ), an 8-aminoquinoline analogue of primaquine, which is currently under clinical trial (phase IIb/III) for the treatment and prevention of malaria, may represent an alternative treatment for leishmaniasis. In this work, we have studied the mechanism of action of TFQ against Leishmania parasites. TFQ impaired the overall bioenergetic metabolism of Leishmania promastigotes, causing a rapid drop in intracellular ATP levels without affecting plasma membrane permeability. TFQ induced mitochondrial dysfunction through the inhibition of cytochrome c reductase (respiratory complex III) with a decrease in the oxygen consumption rate and depolarization of mitochondrial membrane potential. This was accompanied by ROS production, elevation of intracellular Ca2+ levels and concomitant nuclear DNA fragmentation. We conclude that TFQ targets Leishmania mitochondria, leading to an apoptosis-like death process. PMID:20837758

  10. Respiratory complexes III and IV can each bind two molecules of cytochrome c at low ionic strength.

    PubMed

    Moreno-Beltrán, Blas; Díaz-Moreno, Irene; González-Arzola, Katiuska; Guerra-Castellano, Alejandra; Velázquez-Campoy, Adrián; De la Rosa, Miguel A; Díaz-Quintana, Antonio

    2015-02-13

    The transient interactions of respiratory cytochrome c with complexes III and IV is herein investigated by using heterologous proteins, namely human cytochrome c, the soluble domain of plant cytochrome c1 and bovine cytochrome c oxidase. The binding molecular mechanisms of the resulting cross-complexes have been analyzed by Nuclear Magnetic Resonance and Isothermal Titration Calorimetry. Our data reveal that the two cytochrome c-involving adducts possess a 2:1 stoichiometry - that is, two cytochrome c molecules per adduct - at low ionic strength. We conclude that such extra binding sites at the surfaces of complexes III and IV can facilitate the turnover and sliding of cytochrome c molecules and, therefore, the electron transfer within respiratory supercomplexes.

  11. TTC19 Plays a Husbandry Role on UQCRFS1 Turnover in the Biogenesis of Mitochondrial Respiratory Complex III.

    PubMed

    Bottani, Emanuela; Cerutti, Raffaele; Harbour, Michael E; Ravaglia, Sabrina; Dogan, Sukru Anil; Giordano, Carla; Fearnley, Ian M; D'Amati, Giulia; Viscomi, Carlo; Fernandez-Vizarra, Erika; Zeviani, Massimo

    2017-07-06

    Loss-of-function mutations in TTC19 (tetra-tricopeptide repeat domain 19) have been associated with severe neurological phenotypes and mitochondrial respiratory chain complex III deficiency. We previously demonstrated the mitochondrial localization of TTC19 and its link with complex III biogenesis. Here we provide detailed insight into the mechanistic role of TTC19, by investigating a Ttc19(?/?) mouse model that shows progressive neurological and metabolic decline, decreased complex III activity, and increased production of reactive oxygen species. By using both the Ttc19(?/?) mouse model and a range of human cell lines, we demonstrate that TTC19 binds to the fully assembled complex III dimer, i.e., after the incorporation of the iron-sulfur Rieske protein (UQCRFS1). The in situ maturation of UQCRFS1 produces N-terminal polypeptides, which remain bound to holocomplex III. We show that, in normal conditions, these UQCRFS1 fragments are rapidly removed, but when TTC19 is absent they accumulate within complex III, causing its structural and functional impairment. Copyright © 2017. Published by Elsevier Inc.

  12. [Benign congenital myopathy associated with a partial deficiency of complexes I and III of the mitochondrial respiratory chain

    PubMed

    Castro-Gago, M; Eirís, J; Pintos, E; Rodrigo, E; Blanco-Barca, O; Campos, Y; Arenas, J

    Isolated or combined enzyme deficiencies of the mitochondrial respiratory chain results in a number of clinical heterogeneous conditions. When presented in the neonatal period or early in the infancy the course is usually severe, although isolated cases with benign evolution have also been described. To describe the clinical and biochemical characteristics of a child with a benign form of mitochondrial myopathy due to a combined deficiency of the complexes I and III of the respiratory chain. A 40 days-old male, the second son of a young non-consanguineous couple, presented with axial congenital hypotonia, asymmetrical macrocephaly, mild enlargement of the liver, mild coarsening of facial features, increased CK serum values, persistently elevation of serum lactate and lactate/pyruvate ratio and external hydrocephalus. Electromyogram and histological muscle examination were normal but analysis of the respiratory chain disclosed a deficiency of the complexes I and III. From 13 months-age onwards clinical detailed abnormalities progressively ameliorated and also did it serum CK, lactate and external hydrocephalus. We think that on clinical, basic biochemical and histological grounds there are some similarities between this case of congenital unspecific myopathy and benign reversible form of mitochondrial myopathy, arguing in favor of a possible relationship between both conditions.

  13. Effect of High-Carbohydrate Diet on Plasma Metabolome in Mice with Mitochondrial Respiratory Chain Complex III Deficiency

    PubMed Central

    Rajendran, Jayasimman; Tomašić, Nikica; Kotarsky, Heike; Hansson, Eva; Velagapudi, Vidya; Kallijärvi, Jukka; Fellman, Vineta

    2016-01-01

    Mitochondrial disorders cause energy failure and metabolic derangements. Metabolome profiling in patients and animal models may identify affected metabolic pathways and reveal new biomarkers of disease progression. Using liver metabolomics we have shown a starvation-like condition in a knock-in (Bcs1lc.232A>G) mouse model of GRACILE syndrome, a neonatal lethal respiratory chain complex III dysfunction with hepatopathy. Here, we hypothesized that a high-carbohydrate diet (HCD, 60% dextrose) will alleviate the hypoglycemia and promote survival of the sick mice. However, when fed HCD the homozygotes had shorter survival (mean ± SD, 29 ± 2.5 days, n = 21) than those on standard diet (33 ± 3.8 days, n = 30), and no improvement in hypoglycemia or liver glycogen depletion. We investigated the plasma metabolome of the HCD- and control diet-fed mice and found that several amino acids and urea cycle intermediates were increased, and arginine, carnitines, succinate, and purine catabolites decreased in the homozygotes. Despite reduced survival the increase in aromatic amino acids, an indicator of liver mitochondrial dysfunction, was normalized on HCD. Quantitative enrichment analysis revealed that glycine, serine and threonine metabolism, phenylalanine and tyrosine metabolism, and urea cycle were also partly normalized on HCD. This dietary intervention revealed an unexpected adverse effect of high-glucose diet in complex III deficiency, and suggests that plasma metabolomics is a valuable tool in evaluation of therapies in mitochondrial disorders. PMID:27809283

  14. Effect of High-Carbohydrate Diet on Plasma Metabolome in Mice with Mitochondrial Respiratory Chain Complex III Deficiency.

    PubMed

    Rajendran, Jayasimman; Tomašić, Nikica; Kotarsky, Heike; Hansson, Eva; Velagapudi, Vidya; Kallijärvi, Jukka; Fellman, Vineta

    2016-11-01

    Mitochondrial disorders cause energy failure and metabolic derangements. Metabolome profiling in patients and animal models may identify affected metabolic pathways and reveal new biomarkers of disease progression. Using liver metabolomics we have shown a starvation-like condition in a knock-in (Bcs1l(c.232A>G)) mouse model of GRACILE syndrome, a neonatal lethal respiratory chain complex III dysfunction with hepatopathy. Here, we hypothesized that a high-carbohydrate diet (HCD, 60% dextrose) will alleviate the hypoglycemia and promote survival of the sick mice. However, when fed HCD the homozygotes had shorter survival (mean ± SD, 29 ± 2.5 days, n = 21) than those on standard diet (33 ± 3.8 days, n = 30), and no improvement in hypoglycemia or liver glycogen depletion. We investigated the plasma metabolome of the HCD- and control diet-fed mice and found that several amino acids and urea cycle intermediates were increased, and arginine, carnitines, succinate, and purine catabolites decreased in the homozygotes. Despite reduced survival the increase in aromatic amino acids, an indicator of liver mitochondrial dysfunction, was normalized on HCD. Quantitative enrichment analysis revealed that glycine, serine and threonine metabolism, phenylalanine and tyrosine metabolism, and urea cycle were also partly normalized on HCD. This dietary intervention revealed an unexpected adverse effect of high-glucose diet in complex III deficiency, and suggests that plasma metabolomics is a valuable tool in evaluation of therapies in mitochondrial disorders.

  15. Arrangement of the respiratory chain complexes in Saccharomyces cerevisiae supercomplex III2IV2 revealed by single particle cryo-electron microscopy.

    PubMed

    Mileykovskaya, Eugenia; Penczek, Pawel A; Fang, Jia; Mallampalli, Venkata K P S; Sparagna, Genevieve C; Dowhan, William

    2012-06-29

    Here we present for the first time a three-dimensional cryo-EM map of the Saccharomyces cerevisiae respiratory supercomplex composed of dimeric complex III flanked on each side by one monomeric complex IV. A precise fit of the existing atomic x-ray structures of complex III from yeast and complex IV from bovine heart into the cryo-EM map resulted in a pseudo-atomic model of the three-dimensional structure for the supercomplex. The distance between cytochrome c binding sites of complexes III and IV is about 6 nm, which supports proposed channeling of cytochrome c between the individual complexes. The opposing surfaces of complexes III and IV differ considerably from those reported for the bovine heart supercomplex as determined by cryo-EM. A closer association between the individual complex domains at the aqueous membrane interface and larger spaces between the membrane-embedded domains where lipid molecules may reside are also demonstrated. The supercomplex contains about 50 molecules of cardiolipin (CL) with a fatty acid composition identical to that of the inner membrane CL pool, consistent with CL-dependent stabilization of the supercomplex.

  16. Feline respiratory disease complex.

    PubMed

    Cohn, Leah A

    2011-11-01

    Feline respiratory disease complex (FRDC) refers to the characteristic acute presentation of a contagious respiratory or ocular disease caused by one or multiple pathogens. Environmental and host factors impact the transmission, clinical presentation, preventive strategy, and treatment of affected cats. The FRDC is especially problematic in settings where large numbers of cats cohabit, including animal shelters, catteries, and semi-feral colonies. Although elimination of FRDC is an unrealistic goal, improved understanding can lead to strategies to minimize disease impact.

  17. A Single Adaptable Cochaperone-Scaffold Complex Delivers Nascent Iron-Sulfur Clusters to Mammalian Respiratory Chain Complexes I-III.

    PubMed

    Maio, Nunziata; Kim, Ki Soon; Singh, Anamika; Rouault, Tracey A

    2017-04-04

    The iron-sulfur (Fe-S) cluster of the Rieske protein, UQCRFS1, is essential for Complex III (CIII) activity, though the mechanism for Fe-S cluster transfer has not previously been elucidated. Recent studies have shown that the co-chaperone HSC20, essential for Fe-S cluster biogenesis of SDHB, directly binds LYRM7, formerly described as a chaperone that stabilizes UQCRFS1 prior to its insertion into CIII. Here we report that a transient subcomplex involved in CIII assembly, composed of LYRM7 bound to UQCRFS1, interacts with components of an Fe-S transfer complex, consisting of HSC20, its cognate chaperone HSPA9, and the holo-scaffold ISCU. Binding of HSC20 to the LYR motif of LYRM7 in a pre-assembled UQCRFS1-LYRM7 intermediate in the mitochondrial matrix facilitates Fe-S cluster transfer to UQCRFS1. The five Fe-S cluster subunits of Complex I also interact with HSC20 to acquire their clusters, highlighting the crucial role of HSC20 in the assembly of the mitochondrial respiratory chain. Published by Elsevier Inc.

  18. Quantum Computational Studies of Electron Transfer in Respiratory Complex III and its Application for Designing New Mitocan Drugs

    NASA Astrophysics Data System (ADS)

    Hagras, Muhammad Ahmed

    Electron transfer occurs in many biological systems which are imperative to sustain life; oxidative phosphorylation in prokaryotes and eukaryotes, and photophosphorylation in photosynthetic and plant cells are well-balanced and complementary processes. Investigating electron transfer in those natural systems provides detailed knowledge of the atomistic events that lead eventually to production of ATP, or harvesting light energy. Ubiquinol:cytochrome c oxidoreductase complex (also known as bc 1 complex, or respiratory complex III) is a middle player in the electron transport proton pumping orchestra, located in the inner-mitochondrial membrane in eukaryotes or plasma membrane in prokaryotes, which converts the free energy of redox reactions to electrochemical proton gradient across the membrane, following the fundamental chemiosmotic principle discovered by Peter Mitchell 1. In humans, the malfunctioned bc1 complex plays a major role in many neurodegenerative diseases, stress-induced aging, and cancer development, because it produces most of the reactive oxygen species, which are also involved in cellular signaling 2. The mitochondrial bc1 complex has an intertwined dimeric structure comprised of 11 subunits in each monomer, but only three of them have catalytic function, and those are the only domains found in bacterial bc1 complex. The core subunits include: Rieske domain, which incorporates iron-sulfur cluster [2Fe-2S]; trans-membrane cytochrome b domain, incorporating low-potential heme group (heme b L) and high-potential heme group (heme b H); and cytochrome c1 domain, containing heme c1 group and two separate binding sites, Qo (or QP) site where the hydrophobic electron carrier ubihydroquinol QH2 is oxidized, and Qi (or QN) site where ubiquinone molecule Q is reduced 3. Electrons and protons in the bc1 complex flow according to the proton-motive Q-cycle proposed by Mitchell, which includes a unique electron flow bifurcation at the Qo site. At this site, one

  19. Mitochondrial function in flying honeybees (Apis mellifera): respiratory chain enzymes and electron flow from complex III to oxygen.

    PubMed

    Suarez, R K; Staples, J F; Lighton, J R; Mathieu-Costello, O

    2000-03-01

    The biochemical bases for the high mass-specific metabolic rates of flying insects remain poorly understood. To gain insights into mitochondrial function during flight, metabolic rates of individual flying honeybees were measured using respirometry, and their thoracic muscles were fixed for electron microscopy. Mitochondrial volume densities and cristae surface densities, combined with biochemical data concerning cytochrome content per unit mass, were used to estimate respiratory chain enzyme densities per unit cristae surface area. Despite the high content of respiratory enzymes per unit muscle mass, these are accommodated by abundant mitochondria and high cristae surface densities such that enzyme densities per unit cristae surface area are similar to those found in mammalian muscle and liver. These results support the idea that a unit area of mitochondrial inner membrane constitutes an invariant structural unit. Rates of O(2) consumption per unit cristae surface area are much higher than those estimated in mammals as a consequence of higher enzyme turnover rates (electron transfer rates per enzyme molecule) during flight. Cytochrome c oxidase, in particular, operates close to its maximum catalytic capacity (k(cat)). Thus, high flux rates are achieved via (i) high respiratory enzyme content per unit muscle mass and (ii) the operation of these enzymes at high fractional velocities.

  20. High Molecular Weight Forms of Mammalian Respiratory Chain Complex II

    PubMed Central

    Nůsková, Hana; Holzerová, Eliška; Vrbacký, Marek; Pecina, Petr; Hejzlarová, Kateřina; Kľučková, Katarína; Rohlena, Jakub; Neuzil, Jiri; Houštěk, Josef

    2013-01-01

    Mitochondrial respiratory chain is organised into supramolecular structures that can be preserved in mild detergent solubilisates and resolved by native electrophoretic systems. Supercomplexes of respiratory complexes I, III and IV as well as multimeric forms of ATP synthase are well established. However, the involvement of complex II, linking respiratory chain with tricarboxylic acid cycle, in mitochondrial supercomplexes is questionable. Here we show that digitonin-solubilised complex II quantitatively forms high molecular weight structures (CIIhmw) that can be resolved by clear native electrophoresis. CIIhmw structures are enzymatically active and differ in electrophoretic mobility between tissues (500 – over 1000 kDa) and cultured cells (400–670 kDa). While their formation is unaffected by isolated defects in other respiratory chain complexes, they are destabilised in mtDNA-depleted, rho0 cells. Molecular interactions responsible for the assembly of CIIhmw are rather weak with the complexes being more stable in tissues than in cultured cells. While electrophoretic studies and immunoprecipitation experiments of CIIhmw do not indicate specific interactions with the respiratory chain complexes I, III or IV or enzymes of the tricarboxylic acid cycle, they point out to a specific interaction between CII and ATP synthase. PMID:23967256

  1. Suppressors of superoxide production from mitochondrial complex III

    PubMed Central

    Orr, Adam L.; Vargas, Leonardo; Turk, Carolina N.; Baaten, Janine E.; Matzen, Jason T.; Dardov, Victoria J.; Attle, Stephen J.; Li, Jing; Quackenbush, Douglas C.; Goncalves, Renata L. S.; Perevoshchikova, Irina V.; Petrassi, H. Michael; Meeusen, Shelly L.; Ainscow, Edward K.; Brand, Martin D.

    2015-01-01

    Mitochondrial electron transport drives ATP synthesis but also generates reactive oxygen species (ROS), which are both cellular signals and damaging oxidants. Superoxide production by respiratory complex III is implicated in diverse signaling events and pathologies but its role remains controversial. Using high-throughput screening we identified compounds that selectively eliminate superoxide production by complex III without altering oxidative phosphorylation; they modulate retrograde signaling including cellular responses to hypoxic and oxidative stress. PMID:26368590

  2. Organometallic neptunium(III) complexes.

    PubMed

    Dutkiewicz, Michał S; Farnaby, Joy H; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G; Love, Jason B; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on U(III) and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to Np(IV). Here we report the synthesis of three new Np(III) organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that Np(III) complexes could act as single-molecule magnets, and that the lower oxidation state of Np(II) is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key Np(III) orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  3. Organometallic neptunium(III) complexes

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Michał S.; Farnaby, Joy H.; Apostolidis, Christos; Colineau, Eric; Walter, Olaf; Magnani, Nicola; Gardiner, Michael G.; Love, Jason B.; Kaltsoyannis, Nikolas; Caciuffo, Roberto; Arnold, Polly L.

    2016-08-01

    Studies of transuranic organometallic complexes provide a particularly valuable insight into covalent contributions to the metal-ligand bonding, in which the subtle differences between the transuranium actinide ions and their lighter lanthanide counterparts are of fundamental importance for the effective remediation of nuclear waste. Unlike the organometallic chemistry of uranium, which has focused strongly on UIII and has seen some spectacular advances, that of the transuranics is significantly technically more challenging and has remained dormant. In the case of neptunium, it is limited mainly to NpIV. Here we report the synthesis of three new NpIII organometallic compounds and the characterization of their molecular and electronic structures. These studies suggest that NpIII complexes could act as single-molecule magnets, and that the lower oxidation state of NpII is chemically accessible. In comparison with lanthanide analogues, significant d- and f-electron contributions to key NpIII orbitals are observed, which shows that fundamental neptunium organometallic chemistry can provide new insights into the behaviour of f-elements.

  4. Structure of bacterial respiratory complex I.

    PubMed

    Berrisford, John M; Baradaran, Rozbeh; Sazanov, Leonid A

    2016-07-01

    Complex I (NADH:ubiquinone oxidoreductase) plays a central role in cellular energy production, coupling electron transfer between NADH and quinone to proton translocation. It is the largest protein assembly of respiratory chains and one of the most elaborate redox membrane proteins known. Bacterial enzyme is about half the size of mitochondrial and thus provides its important "minimal" model. Dysfunction of mitochondrial complex I is implicated in many human neurodegenerative diseases. The L-shaped complex consists of a hydrophilic arm, where electron transfer occurs, and a membrane arm, where proton translocation takes place. We have solved the crystal structures of the hydrophilic domain of complex I from Thermus thermophilus, the membrane domain from Escherichia coli and recently of the intact, entire complex I from T. thermophilus (536 kDa, 16 subunits, 9 iron-sulphur clusters, 64 transmembrane helices). The 95Å long electron transfer pathway through the enzyme proceeds from the primary electron acceptor flavin mononucleotide through seven conserved Fe-S clusters to the unusual elongated quinone-binding site at the interface with the membrane domain. Four putative proton translocation channels are found in the membrane domain, all linked by the central flexible axis containing charged residues. The redox energy of electron transfer is coupled to proton translocation by the as yet undefined mechanism proposed to involve long-range conformational changes. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.

  5. Genetics Home Reference: mitochondrial complex III deficiency

    MedlinePlus

    ... Complex III is found in cell structures called mitochondria , which convert the energy from food into a ... CYB gene is found in DNA located in mitochondria, called mitochondrial DNA (mtDNA). This location may help ...

  6. Electron tunneling in respiratory complex I

    PubMed Central

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

    2010-01-01

    NADH:ubiquinone oxidoreductase (complex I) plays a central role in the respiratory electron transport chain by coupling the transfer of electrons from NADH to ubiquinone to the creation of the proton gradient across the membrane necessary for ATP synthesis. Here the atomistic details of electronic wiring of all Fe/S clusters in complex I are revealed by using the tunneling current theory and computer simulations; both density functional theory and semiempirical electronic structure methods were used to examine antiferromagnetically coupled spin states and corresponding tunneling wave functions. Distinct electron tunneling pathways between neighboring Fe/S clusters are identified; the pathways primarily consist of two cysteine ligands and one additional key residue. Internal water between protein subunits is identified as an essential mediator enhancing the overall electron transfer rate by almost three orders of magnitude to achieve a physiologically significant value. The identified key residues are further characterized by sensitivity of electron transfer rates to their mutations, examined in simulations, and their conservation among complex I homologues. The unusual electronic structure properties of Fe4S4 clusters in complex I explain their remarkable efficiency of electron transfer. PMID:20974925

  7. A sustained deficiency of mitochondrial respiratory complex III induces an apoptotic cell death through the p53-mediated inhibition of pro-survival activities of the activating transcription factor 4.

    PubMed

    Evstafieva, A G; Garaeva, A A; Khutornenko, A A; Klepikova, A V; Logacheva, M D; Penin, A A; Novakovsky, G E; Kovaleva, I E; Chumakov, P M

    2014-11-06

    Generation of energy in mitochondria is subjected to physiological regulation at many levels, and its malfunction may result in mitochondrial diseases. Mitochondrial dysfunction is associated with different environmental influences or certain genetic conditions, and can be artificially induced by inhibitors acting at different steps of the mitochondrial electron transport chain (ETC). We found that a short-term (5 h) inhibition of ETC complex III with myxothiazol results in the phosphorylation of translation initiation factor eIF2α and upregulation of mRNA for the activating transcription factor 4 (ATF4) and several ATF4-regulated genes. The changes are characteristic for the adaptive integrated stress response (ISR), which is known to be triggered by unfolded proteins, nutrient and metabolic deficiency, and mitochondrial dysfunctions. However, after a prolonged incubation with myxothiazol (13-17 h), levels of ATF4 mRNA and ATF4-regulated transcripts were found substantially suppressed. The suppression was dependent on the p53 response, which is triggered by the impairment of the complex III-dependent de novo biosynthesis of pyrimidines by mitochondrial dihydroorotate dehydrogenase. The initial adaptive induction of ATF4/ISR acted to promote viability of cells by attenuating apoptosis. In contrast, the induction of p53 upon a sustained inhibition of ETC complex III produced a pro-apoptotic effect, which was additionally stimulated by the p53-mediated abrogation of the pro-survival activities of the ISR. Interestingly, a sustained inhibition of ETC complex I by piericidine did not induce the p53 response and stably maintained the pro-survival activation of ATF4/ISR. We conclude that a downregulation of mitochondrial ETC generally induces adaptive pro-survival responses, which are specifically abrogated by the suicidal p53 response triggered by the genetic risks of the pyrimidine nucleotide deficiency.

  8. Reconstruction of Extracellular Respiratory Pathways for Iron(III) Reduction in Shewanella Oneidensis Strain MR-1

    PubMed Central

    Coursolle, Dan; Gralnick, Jeffrey A.

    2012-01-01

    Shewanella oneidensis strain MR-1 is a facultative anaerobic bacterium capable of respiring a multitude of electron acceptors, many of which require the Mtr respiratory pathway. The core Mtr respiratory pathway includes a periplasmic c-type cytochrome (MtrA), an integral outer-membrane β-barrel protein (MtrB), and an outer-membrane-anchored c-type cytochrome (MtrC). Together, these components facilitate transfer of electrons from the c-type cytochrome CymA in the cytoplasmic membrane to electron acceptors at and beyond the outer-membrane. The genes encoding these core proteins have paralogs in the S. oneidensis genome (mtrB and mtrA each have four while mtrC has three) and some of the paralogs of mtrC and mtrA are able to form functional Mtr complexes. We demonstrate that of the additional three mtrB paralogs found in the S. oneidensis genome, only MtrE can replace MtrB to form a functional respiratory pathway to soluble iron(III) citrate. We also evaluate which mtrC/mtrA paralog pairs (a total of 12 combinations) are able to form functional complexes with endogenous levels of mtrB paralog expression. Finally, we reconstruct all possible functional Mtr complexes and test them in a S. oneidensis mutant strain where all paralogs have been eliminated from the genome. We find that each combination tested with the exception of MtrA/MtrE/OmcA is able to reduce iron(III) citrate at a level significantly above background. The results presented here have implications toward the evolution of anaerobic extracellular respiration in Shewanella and for future studies looking to increase the rates of substrate reduction for water treatment, bioremediation, or electricity production. PMID:22363330

  9. Luminescence of europium (III) complexes for visualization

    NASA Astrophysics Data System (ADS)

    Kolontaeva, Olga A.; Pozharov, Mikhail V.; Korolovich, Vladimir F.; Khokhlova, Anastasia R.; Kirdyanova, Anna N.; Burmistrova, Natalia A.; Zakharova, Tamara V.; Goryacheva, Irina Y.

    2016-04-01

    With the purpose to develop bright non-toxic luminescent label for theranostic application we have studied complexation of lanthanide dipicolinates (2,6-pyridinedicarboxylates) by sodium alginate and effect of thermal exposure of synthesized micro-capsules on their luminescent properties. Synthesized micro-capsules are stable in acidic medium but dissolve at pH ~ 4 due to transformation of cationic europium dipicolinate complex to anionic. Luminescence studies have shown that emission spectra of europium(III)-alginate complexes (both chloride and dipicolinate) contain two intensive bands characteristic to Eu3+ ion (5D0 --> 7F1 (590 nm) and 5D0 --> 7F1 (612 nm)). We have also found that at 160ºC europium(III)- alginate micro-capsules decompose to black, soot-like substance, therefore, their thermal treatment must be performed in closed environment (i.e., sealed ampoules).

  10. Quantum electron tunneling in respiratory complex I.

    PubMed

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

    2011-05-12

    We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. While the one-electron tunneling approximation is found to hold in electron tunneling between the antiferromagnetic binuclear and tetranuclear Fe/S clusters without major orbital or spin rearrangement of the core electrons, induced polarization of the core electrons contributes significantly to decrease the electron transfer rates to 19-56 %. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of the electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A signature of the wave properties of electrons is observed as distinct quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included is in good agreement with a reported phenomenological relation.

  11. Respiratory Care Considerations for Children with Medical Complexity

    PubMed Central

    Chiang, Jackie; Amin, Reshma

    2017-01-01

    Children with medical complexity (CMC) are a growing population of diagnostically heterogeneous children characterized by chronic conditions affecting multiple organ systems, the use of medical technology at home as well as intensive healthcare service utilization. Many of these children will experience either a respiratory-related complication and/or they will become established on respiratory technology at home during their care trajectory. Therefore, healthcare providers need to be familiar with the respiratory related complications commonly experienced by CMC as well as the indications, technical and safety considerations and potential complications that may arise when caring for CMC using respiratory technology at home. This review will outline the most common respiratory disease manifestations experienced by CMC, and discuss various respiratory-related treatment options that can be considered, including tracheostomy, invasive and non-invasive ventilation, as well as airway clearance techniques. The caregiver requirements associated with caring for CMC using respiratory technology at home will also be reviewed. PMID:28534851

  12. Helical lanthanide(III) complexes with chiral nonaaza macrocycle.

    PubMed

    Gregoliński, Janusz; Starynowicz, Przemysław; Hua, KimNgan T; Lunkley, Jamie L; Muller, Gilles; Lisowski, Jerzy

    2008-12-31

    The chiral nonaazamacrocyclic amine L, which is a reduction product of the 3 + 3 Schiff base macrocycle, wraps around the lanthanide(III) ions to form enantiopure helical complexes. These Ce(III), Pr(III), Nd(III), Eu(III), Gd(III), Tb(III), Er(III), Yb(III) and Lu(III) complexes have been isolated in enantiopure form and have been characterized by spectroscopic methods. X-ray crystal structures of the Ln(III) complexes with L show that the thermodynamic product of the complexation of the RRRRRR-isomer of the macrocycle is the (M)-helical complex in the case of Ce(III), Pr(III), Nd(III) and Eu(III). In contrast, the (P)-helical complex is the thermodynamic product in the case of Yb(III) and Lu(III). The NMR and CD spectra show that the (M)-helicity for the kinetic complexation product of the RRRRRR-isomer of the macrocycle is preferred for all investigated lanthanide(III) ions, while the preferred helicity of the thermodynamic product is (M) for the early lanthanide(III) ions and (P) for the late lanthanide(III) ions. In the case of the late lanthanide(III) ions, a slow inversion of helicity between the kinetic (M)-helical product and the thermodynamic (P)-helical product is observed in solution. For Er(III), Yb(III) and Lu(III) both forms have been isolated in pure form and characterized by NMR and CD. The analysis of 2D NMR spectra of the Lu(III) complex reveals the NOE correlations that prove that the helical structure is retained in solution. The NMR spectra also reveal large isotopic effect on the 1H NMR shifts of paramagnetic Ln(III) complexes, related to NH/ND exchange. Photophysical measurements show that L(RRRRRR) appears to favor an efficient 3pipi*-to-Ln energy transfer process taking place for Eu(III) and Tb(III), but these Eu(III)- and Tb(III)-containing complexes with L(RRRRRR) lead to small luminescent quantum yields due to an incomplete intersystem crossing (isc) transfer, a weak efficiency of the luminescence sensitization by the ligand, and

  13. Glucose Modulates Respiratory Complex I Activity in Response to Acute Mitochondrial Dysfunction

    PubMed Central

    Cannino, Giuseppe; El-Khoury, Riyad; Pirinen, Marja; Hutz, Bettina; Rustin, Pierre; Jacobs, Howard T.; Dufour, Eric

    2012-01-01

    Proper coordination between glycolysis and respiration is essential, yet the regulatory mechanisms involved in sensing respiratory chain defects and modifying mitochondrial functions accordingly are unclear. To investigate the nature of this regulation, we introduced respiratory bypass enzymes into cultured human (HEK293T) cells and studied mitochondrial responses to respiratory chain inhibition. In the absence of respiratory chain inhibitors, the expression of alternative respiratory enzymes did not detectably alter cell physiology or mitochondrial function. However, in permeabilized cells NDI1 (alternative NADH dehydrogenase) bypassed complex I inhibition, whereas alternative oxidase (AOX) bypassed complex III or IV inhibition. In contrast, in intact cells the effects of the AOX bypass were suppressed by growth on glucose, whereas those produced by NDI1 were unaffected. Moreover, NDI1 abolished the glucose suppression of AOX-driven respiration, implicating complex I as the target of this regulation. Rapid Complex I down-regulation was partly released upon prolonged respiratory inhibition, suggesting that it provides an “emergency shutdown” system to regulate metabolism in response to dysfunctions of the oxidative phosphorylation. This system was independent of HIF1, mitochondrial superoxide, or ATP synthase regulation. Our findings reveal a novel pathway for adaptation to mitochondrial dysfunction and could provide new opportunities for combatting diseases. PMID:23007390

  14. Optical properties of the Eu(III)-La(III)-complex-doped polyolefine film and rod samples

    NASA Astrophysics Data System (ADS)

    Pogreb, Roman; Popov, Oleg; Lirtsman, Vlad; Pyshkin, Oleg; Kazachkov, Alexander; Musin, Albina; Finkelshtein, Binyamin; Shmukler, Yuri; Davidov, Dan; Bormashenko, Edward

    2005-04-01

    The work is devoted to luminescent properties of trivalent lanthanide complexes dispersed in thermoplastic host matrices. Polyethylene-based film and polypropylene-based rod both doped with these complexes were manufactured using an extrusion technique. Two kinds of dopants were used: Eu(III)-thenoyltrifluoroacetone-1,10-phenanthroline complex (Eu(III)) and Eu(III)-La(III)-1,10-phenanthroline complex (Eu(III)-La(III)). Comparison was made between these samples regarding absorption, excitation, emission and a lifetime of luminescence. Dependence of emission intensity on the excitation energy was determined. Emission spectra of the films were studied at room and helium temperatures. Optical properties of Eu(III) samples are different from Eu(III)-La(III) samples. Significant difference in spectra of these two types of samples may be attributed to the La(III) action.

  15. Interaction of complexes I, III, and IV within the bovine respirasome by single particle cryoelectron tomography

    PubMed Central

    Dudkina, Natalya V.; Kudryashev, Mikhail; Stahlberg, Henning; Boekema, Egbert J.

    2011-01-01

    The respirasome is a multisubunit supercomplex of the respiratory chain in mitochondria. Here we report the 3D reconstruction of the bovine heart respirasome, composed of dimeric complex III and single copies of complex I and IV, at about 2.2-nm resolution, determined by cryoelectron tomography and subvolume averaging. Fitting of X-ray structures of single complexes I, III2, and IV with high fidelity allows interpretation of the model at the level of secondary structures and shows how the individual complexes interact within the respirasome. Surprisingly, the distance between cytochrome c binding sites of complexes III2 and IV is about 10 nm. Modeling indicates a loose interaction between the three complexes and provides evidence that lipids are gluing them at the interfaces. PMID:21876144

  16. Building a Beautiful Beast: Mammalian Respiratory Complex I.

    PubMed

    Guaras, Adela M; Enríquez, José Antonio

    2017-01-10

    Understanding the mammalian respiratory complex I assembly has been an arduous task due to the lack of appropriate techniques and the complexity of the process. In this issue, a new tour de force based on complexome profiling provides an encyclopedic description of the process (Guerrero-Castillo et al., 2017). Copyright © 2017. Published by Elsevier Inc.

  17. Is there a genetic solution to bovine respiratory disease complex?

    USDA-ARS?s Scientific Manuscript database

    Bovine respiratory disease complex (BRDC) is a complex multi-factor disease, which increases costs and reduces revenue from feedlot cattle. Multiple stressors and pathogens (viral and bacterial) have been implicated in the etiology of BRDC, therefore multiple approaches will be needed to evaluate a...

  18. Lanthanide(III) and Yttrium(III) Complexes of Benzimidazole-2-Acetic Acid: Synthesis, Characterisation and Effect of La(III) Complex on Germination of Wheat

    PubMed Central

    Gudasi, Kalagouda B.; Shenoy, Rashmi V.; Vadavi, Ramesh S.; Patil, Manjula S.; Patil, Siddappa A.; Hanchinal, Rayappa R.; Desai, Srinivas A.; Lohithaswa, H.

    2006-01-01

    The synthesis and characterisation of lanthanide(III) and yttrium(III) nitrate complexes of benzimidazole-2-acetic acid (HBIA) are reported. The complexes have been characterised by elemental analysis, molar conductance, magnetic studies, IR, 1H NMR, UV-visible, EPR, and TG/DTA studies. They have the stoichiometry [Ln3(BIA)2(NO3)7(H2O)4] · 3H2O where Ln=La(III), Pr(III), Nd(II), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), and Y(III). The effect of La(III) complex on germination, coleoptile, and root length of two local varieties of wheat DWR-195 and GW-349 for different treatment periods has been investigated. The complex was found to exhibit enhanced activity, compared to HBIA or metal salt alone at lower treatment periods. PMID:17497017

  19. Experimental and Theoretical Studies on Biologically Active Lanthanide (III) Complexes

    NASA Astrophysics Data System (ADS)

    Kostova, I.; Trendafilova, N.; Georgieva, I.; Rastogi, V. K.; Kiefer, W.

    2008-11-01

    The complexation ability and the binding mode of the ligand coumarin-3-carboxylic acid (HCCA) to La(III), Ce(III), Nd(III), Sm(III), Gd(III) and Dy(III) lanthanide ions (Ln(III)) are elucidated at experimental and theoretical level. The complexes were characterized using elemental analysis, DTA and TGA data as well as 1H NMR and 13C NMR spectra. FTIR and Raman spectroscopic techniques as well as DFT quantum chemical calculations were used for characterization of the binding mode and the structures of lanthanide(III) complexes of HCCA. The metal—ligand binding mode is predicted through molecular modeling and energy estimation of different Ln—CCA structures using B3LYP/6-31G(d) method combined with a large quasi-relativistic effective core potential for lanthanide ion. The energies obtained predict bidentate coordination of CCA- to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen. Detailed vibrational analysis of HCCA, CCA- and Ln(III) complexes based on both calculated and experimental frequencies confirms the suggested metal—ligand binding mode. The natural bonding analysis predicts strongly ionic character of the Ln(III)-CCA bonding in the- complexes studied. With the relatively resistant tumor cell line K-562 we obtained very interesting in-vitro results which are in accordance with our previously published data concerning the activity of lanthanide(III) complexes with other coumarin derivatives.

  20. Structure of mammalian respiratory complex I

    PubMed Central

    Hirst, Judy

    2016-01-01

    Complex I (NADH:ubiquinone oxidoreductase), one of the largest membrane-bound enzymes in the cell, powers ATP synthesis in mammalian mitochondria by using the reducing potential of NADH to drive protons across the inner membrane. Mammalian complex I1 contains 45 subunits, comprising 14 core subunits that house the catalytic machinery and are conserved from bacteria to humans, and a mammalian-specific cohort of 31 supernumerary subunits1,2. Knowledge about the structures and functions of the supernumerary subunits is fragmentary. Here, we describe a 4.2 Å resolution single-particle cryoEM structure of complex I from Bos taurus. We locate and model all 45 subunits to provide the entire structure of the mammalian complex. Furthermore, computational sorting of the particles identified different structural classes, related by subtle domain movements, which reveal conformationally-dynamic regions and match biochemical descriptions of the ‘active-to-deactive’ enzyme transition that occurs during hypoxia3,4. Thus, our structures provide a foundation for understanding complex I assembly5 and the effects of mutations that cause clinically-relevant complex I dysfunctions6, insights into the structural and functional roles of the supernumerary subunits, and new information on the mechanism and regulation of catalysis. PMID:27509854

  1. Architecture of mammalian respiratory complex I.

    PubMed

    Vinothkumar, Kutti R; Zhu, Jiapeng; Hirst, Judy

    2014-11-06

    Complex I (NADH:ubiquinone oxidoreductase) is essential for oxidative phosphorylation in mammalian mitochondria. It couples electron transfer from NADH to ubiquinone with proton translocation across the energy-transducing inner membrane, providing electrons for respiration and driving ATP synthesis. Mammalian complex I contains 44 different nuclear- and mitochondrial-encoded subunits, with a combined mass of 1 MDa. The 14 conserved 'core' subunits have been structurally defined in the minimal, bacterial complex, but the structures and arrangement of the 30 'supernumerary' subunits are unknown. Here we describe a 5 Å resolution structure of complex I from Bos taurus heart mitochondria, a close relative of the human enzyme, determined by single-particle electron cryo-microscopy. We present the structures of the mammalian core subunits that contain eight iron-sulphur clusters and 60 transmembrane helices, identify 18 supernumerary transmembrane helices, and assign and model 14 supernumerary subunits. Thus, we considerably advance knowledge of the structure of mammalian complex I and the architecture of its supernumerary ensemble around the core domains. Our structure provides insights into the roles of the supernumerary subunits in regulation, assembly and homeostasis, and a basis for understanding the effects of mutations that cause a diverse range of human diseases.

  2. Architecture of mammalian respiratory complex I

    PubMed Central

    Hirst, Judy

    2014-01-01

    Complex I (NADH:ubiquinone oxidoreductase) is essential for oxidative phosphorylation in mammalian mitochondria. It couples electron transfer from NADH to ubiquinone with proton translocation across the energy-transducing inner membrane, providing electrons for respiration and driving ATP synthesis. Mammalian complex I contains 44 different nuclear- and mitochondrial-encoded subunits, with a combined mass of 1 MDa. The fourteen conserved ‘core’ subunits have been structurally defined in the minimal, bacterial complex, but the structures and arrangement of the 30 ‘supernumerary’ subunits are unknown. Here, we describe a 5 Å resolution structure of complex I from Bos taurus heart mitochondria, a close relative of the human enzyme, determined by single-particle electron cryo-microscopy. We present the structures of the mammalian core subunits that contain eight iron-sulphur clusters and 60 transmembrane helices, identify 18 supernumerary transmembrane helices, and assign and model 14 supernumerary subunits. Thus, we significantly advance knowledge of the structure of mammalian complex I and the architecture of its supernumerary ensemble around the core domains. Our structure provides insights into the roles of the supernumerary subunits in regulation, assembly and homeostasis, and a basis for understanding the effects of mutations that cause a diverse range of human diseases. PMID:25209663

  3. The Assembly Pathway of Mitochondrial Respiratory Chain Complex I.

    PubMed

    Guerrero-Castillo, Sergio; Baertling, Fabian; Kownatzki, Daniel; Wessels, Hans J; Arnold, Susanne; Brandt, Ulrich; Nijtmans, Leo

    2017-01-10

    Mitochondrial complex I is the largest integral membrane enzyme of the respiratory chain and consists of 44 different subunits encoded in the mitochondrial and nuclear genome. Its biosynthesis is a highly complicated and multifaceted process involving at least 14 additional assembly factors. How these subunits assemble into a functional complex I and where the assembly factors come into play is largely unknown. Here, we applied a dynamic complexome profiling approach to elucidate the assembly of human mitochondrial complex I and its further incorporation into respiratory chain supercomplexes. We delineate the stepwise incorporation of all but one subunit into a series of distinct assembly intermediates and their association with known and putative assembly factors, which had not been implicated in this process before. The resulting detailed and comprehensive model of complex I assembly is fully consistent with recent structural data and the remarkable modular architecture of this multiprotein complex. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Synthesis, thermal and spectroscopic behaviors of metal-drug complexes: La(III), Ce(III), Sm(III) and Y(III) amoxicillin trihydrate antibiotic drug complexes.

    PubMed

    Refat, Moamen S; Al-Maydama, Hussein M A; Al-Azab, Fathi M; Amin, Ragab R; Jamil, Yasmin M S

    2014-07-15

    The metal complexes of Amoxicillin trihydrate with La(III), Ce(III), Sm(III) and Y(III) are synthesized with 1:1 (metal:Amox) molar ratio. The suggested formula structures of the complexes are based on the results of the elemental analyses, molar conductivity, (infrared, UV-visible and fluorescence) spectra, effective magnetic moment in Bohr magnetons, as well as the thermal analysis (TG), and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results obtained suggested that Amoxicillin reacted with metal ions as tridentate ligands, coordinating the metal ion through its amino, imino, and β-lactamic carbonyl. The kinetic thermodynamic parameters such as: Ea, ΔH(*), ΔS(*) and ΔG(*) were estimated from the DTG curves.

  5. Luminescense properties of new complexes of Eu(III) and Tb(III) with heterotopic ligands

    NASA Astrophysics Data System (ADS)

    Patroniak, Violetta; Hnatejko, Zbigniew; Grochowska, Agnieszka M.; Stefankiewicz, Artur R.

    2006-07-01

    As a result of coordination between ligands L and L' and europium(III) and terbium(III) ions, the new architectures were formed. The formulae of the complexes have been assigned on the basis of the spectroscopic data in solution and microanalyses. The europium complexes show excellent luminescence properties with high quantum yield ( 1b-Eu 3L2) and effective intramolecular energy transfer from the ligand to the Eu(III) ions.

  6. Luminescense properties of new complexes of Eu(III) and Tb(III) with heterotopic ligands.

    PubMed

    Patroniak, Violetta; Hnatejko, Zbigniew; Grochowska, Agnieszka M; Stefankiewicz, Artur R

    2006-07-01

    As a result of coordination between ligands L and L' and europium(III) and terbium(III) ions, the new architectures were formed. The formulae of the complexes have been assigned on the basis of the spectroscopic data in solution and microanalyses. The europium complexes show excellent luminescence properties with high quantum yield (1b-Eu(3)L(2)) and effective intramolecular energy transfer from the ligand to the Eu(III) ions.

  7. Novel, highly photoluminescent Eu(III) and Tb(III) tetrazolate-2-pyridine-1-oxide complexes

    NASA Astrophysics Data System (ADS)

    Pietraszkiewicz, Marek; Mal, Suraj; Pietraszkiewicz, Oksana

    2012-07-01

    Tetrazole-2-pyridine-1-oxide was prepared from 2-cyanopyridine and sodium azide, followed by oxidation with m-chloroperbenzoic acid. This ligand forms neutral 1:3 complexes with Eu(III) and Tb(III) cations. The complexes are photoluminescent in solution, with photoluminescence quantum yields 13% and 31%, respectively.

  8. Hexaammine Complexes of Cr(III) and Co(III): A Spectral Study.

    ERIC Educational Resources Information Center

    Brown, D. R.; Pavlis, R. R.

    1985-01-01

    Procedures are provided for experiments containing complex ions with octahedral symmetry, hexaamminecobalt(III) chloride and hexaamminechromium(III) nitrate, so students can interpret fully the ultra violet/visible spectra of the complex cations in terms of the ligand field parameters, 10 "Dq," the Racah interelectron repulsion parameters, "B,"…

  9. Hexaammine Complexes of Cr(III) and Co(III): A Spectral Study.

    ERIC Educational Resources Information Center

    Brown, D. R.; Pavlis, R. R.

    1985-01-01

    Procedures are provided for experiments containing complex ions with octahedral symmetry, hexaamminecobalt(III) chloride and hexaamminechromium(III) nitrate, so students can interpret fully the ultra violet/visible spectra of the complex cations in terms of the ligand field parameters, 10 "Dq," the Racah interelectron repulsion parameters, "B,"…

  10. Potentiometry: A Chromium (III) -- EDTA Complex

    ERIC Educational Resources Information Center

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  11. Potentiometry: A Chromium (III) -- EDTA Complex

    ERIC Educational Resources Information Center

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  12. A mouse model of mitochondrial complex III dysfunction induced by myxothiazol

    SciTech Connect

    Davoudi, Mina; Kallijärvi, Jukka; Marjavaara, Sanna; Kotarsky, Heike; Hansson, Eva; Levéen, Per; Fellman, Vineta

    2014-04-18

    Highlights: • Reversible chemical inhibition of complex III in wild type mouse. • Myxothiazol causes decreased complex III activity in mouse liver. • The model is useful for therapeutic trials to improve mitochondrial function. - Abstract: Myxothiazol is a respiratory chain complex III (CIII) inhibitor that binds to the ubiquinol oxidation site Qo of CIII. It blocks electron transfer from ubiquinol to cytochrome b and thus inhibits CIII activity. It has been utilized as a tool in studies of respiratory chain function in in vitro and cell culture models. We developed a mouse model of biochemically induced and reversible CIII inhibition using myxothiazol. We administered myxothiazol intraperitoneally at a dose of 0.56 mg/kg to C57Bl/J6 mice every 24 h and assessed CIII activity, histology, lipid content, supercomplex formation, and gene expression in the livers of the mice. A reversible CIII activity decrease to 50% of control value occurred at 2 h post-injection. At 74 h only minor histological changes in the liver were found, supercomplex formation was preserved and no significant changes in the expression of genes indicating hepatotoxicity or inflammation were found. Thus, myxothiazol-induced CIII inhibition can be induced in mice for four days in a row without overt hepatotoxicity or lethality. This model could be utilized in further studies of respiratory chain function and pharmacological approaches to mitochondrial hepatopathies.

  13. Current topics on inhibitors of respiratory complex I.

    PubMed

    Murai, Masatoshi; Miyoshi, Hideto

    2016-07-01

    There are a variety of chemicals which regulate the functions of bacterial and mitochondrial complex I. Some of them, such as rotenone and piericidin A, have been indispensable molecular tools in mechanistic studies on complex I. A large amount of experimental data characterizing the actions of complex I inhibitors has been accumulated so far. Recent X-ray crystallographic structural models of entire complex I may be helpful to carefully interpret this data. We herein focused on recent hot topics on complex I inhibitors and the subjects closely connected to these inhibitors, which may provide useful information not only on the structural and functional aspects of complex I, but also on drug design targeting this enzyme. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.

  14. Luminescent xerogels obtained through embedding Tb(III) and Eu(III) complexes in silica matrix

    NASA Astrophysics Data System (ADS)

    Stan, Corneliu S.; Marcotte, Nathalie; Secula, Marius S.; Popa, Marcel

    2013-07-01

    The paper reports the preparation of two luminescent xerogels through embedding in a silica matrix of Tb(III) and Eu(III) complexes using succinimide (SI) and N-hydroxysuccinimide (NHSI) as ligands. In the first stage, Tb(III) and Eu(III) complexes with N-hydroxysuccinimide and succinimide were prepared at 1:3 metal to ligand ratio. Strong luminescent emission was observed only in case of Eu(III)-SI and Tb(III)-NHSI complexes while the Eu(III)-NHSI and Tb(III)-SI complexes exhibited none or weak photoluminescent properties. In the second stage, the selected highly luminescent complexes were embedded in silica matrices via a sol-gel procedure leading to the formation of xerogels with transparent-glassy aspect which keep the remarkable photoluminescence properties of the free complexes. The selected, highly luminescent free complexes and their correspondent silica xerogels were investigated through thermal analysis, powder XRD, SEM, FT-IR and fluorescence spectroscopy. Their excellent photoluminescent properties and excitation spectra, conveniently located in UV-A region, might recommend these materials for applications in optoelectronic devices where photonic conversion layers are required.

  15. Complexation of N4-Tetradentate Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Meier, G. Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2012-12-06

    To improve understanding of aza-complexants in trivalent actinide–lanthanide separations, a series of tetradentate N-donor ligands have been synthesized and their complexation of americium(III) and neodymium(III) investigated by UV–visible spectrophotometry in methanolic solutions. The six pyridine/alkyl amine/imine ligands are N,N0-bis(2-methylpyridyl)-1,2-diaminoethane, N,N0-bis(2-methylpyridyl)-1,3-diaminopropane, trans-N,N-bis(2-pyridylmethyl)-1,2-diaminocyclohexane (BPMDAC), N,N’-bis(2-pyridylmethyl)piperazine, N,N’-bis-[pyridin-2-ylmethylene]ethane-1,2-diamine, and trans-N,Nbis-([pyridin-2-ylmethylene]-cyclohexane-1,2-diamine. Each ligand has two pyridine groups and two aliphatic amine/imine N-donor atoms arranged with different degrees of preorganization and structural backbone rigidity. Conditional stability constants for the complexes of Am(III) and Nd(III) by these ligands establish the selectivity patterns. The overall selectivity of Am(III) over Nd(III) is similar to that reported for the terdentate bis(dialkyltriazinyl)pyridine molecules. The cyclohexane amine derivative (BPMDAC) is the strongest complexant and shows the highest selectivity for Am(III) over Nd(III) while the imines appear to prefer a bridging arrangement between two cations. These results suggest that this series of ligands could be employed to develop an enhanced actinide(III)– lanthanide(III) separation system.

  16. Mechanisms of Sb(III) Photooxidation by the Excitation of Organic Fe(III) Complexes.

    PubMed

    Kong, Linghao; He, Mengchang

    2016-07-05

    Organic Fe(III) complexes are widely distributed in the aqueous environment, which can efficiently generate free radicals under light illumination, playing a significant role in heavy metal speciation. However, the potential importance of the photooxidation of Sb(III) by organic Fe(III) complexes remains unclear. Therefore, the photooxidation mechanisms of Sb(III) were comprehensively investigated in Fe(III)-oxalate, Fe(III)-citrate and Fe(III)-fulvic acid (FA) solutions by kinetic measurements and modeling. Rapid photooxidation of Sb(III) was observed in an Fe(III)-oxalate solution over the pH range of 3 to 7. The addition of tert-butyl alcohol (TBA) as an ·OH scavenger quenched the Sb(III) oxidation, suggesting that ·OH is an important oxidant for Sb(III). However, the incomplete quenching of Sb(III) oxidation indicated the existence of other oxidants, presumably an Fe(IV) species in irradiated Fe(III)-oxalate solution. In acidic solutions, ·OH may be formed by the reaction of Fe(II)(C2O4) with H2O2, but a hypothetical Fe(IV) species may be generated by the reaction of Fe(II)(C2O4)2(2-) with H2O2 at higher pH. Kinetic modeling provides a quantitative explanation of the results. Evidence for the existence of ·OH and hypothetical Fe(IV) was also observed in an irradiated Fe(III)-citrate and Fe(III)-FA system. This study demonstrated an important pathway of Sb(III) oxidation in surface waters.

  17. Thermal and optical properties of Tb(III), Eu(III) and Tb(III)/Eu(III) co-complexed silicone fluorinated acrylate copolymer

    NASA Astrophysics Data System (ADS)

    Zhai, Yinfeng; Xie, Hongde; Cai, Haijun; Cai, Peiqing; Seo, Hyo Jin

    2015-07-01

    Tb(III), Eu(III) and Tb(III)/Eu(III) activated silicone fluorinated acrylate (SFA) have been successfully synthesized using the method of semi-continuous emulsion polymerization. The copolymers are characterized by flourier transform infrared (FT-IR), thermal gravity analysis (TGA), photoluminescence excitation (PLE) and emission (PL) spectroscopy. The copolymer containing Tb(III) and Eu(III) ions display green and red luminescent colors under UV light excitation, respectively. The TGA curves show the thermal decomposition temperatures of the copolymers are up to about 300 °C. The PL spectra show a strong green emission at 546 nm (5D4 → 7F5) of Tb(III) complexed copolymers, and show a prominent red emission at 615 nm (5D0 → 7F2) of Eu(III) complexed copolymers. Different concentrations of Eu(III) and Tb(III) ions are introduced into the copolymer and the energy transfer from Tb(III) to Eu(III) ions in the copolymer was found. Thus, based on the results it can be suggested that SFA:Eu(III), SFA:Tb(III) and SFA:Tb(III)/Eu(III) can be used potentially as luminescent materials.

  18. Mobility and recalcitrance of organo-chromium(III) complexes.

    PubMed

    Puzon, Geoffrey J; Tokala, Ranjeet K; Zhang, Hua; Yonge, David; Peyton, Brent M; Xun, Luying

    2008-02-01

    Hexavalent chromium [Cr(VI)] is a major industrial pollutant. Bioremediation of Cr(VI) to Cr(III) is a viable clean-up approach. However, Cr(VI) bioreduction also produces soluble organo-Cr(III) complexes, and little is known about their behavior in the environment. When tested with soil columns, citrate-Cr(III) showed little sorption to soil; malate-Cr(III) had limited partitioning with soil; and histidine-Cr(III) exhibited significant interaction with soil. It appears that the mobility varies depending on the organic ligand. Further, Ralstonia eutropha JMP 134 and Pseudomonas aeruginosa pAO1 readily degraded malate, citrate, and histidine, but not the corresponding organo-Cr(III) complexes. The recalcitrance is not due to toxicity, but the complexes are likely to cause hindrance to enzymes, as malate dehydrogenase and amino acid oxidase could not use malate-Cr(III) and histidine-Cr(III), respectively. The data are in agreement with the reports of soluble organo-Cr(III) complexes in the environment.

  19. Microbiology devices; reclassification of nucleic acid-based systems for mycobacterium tuberculosis complex in respiratory specimens. Final rule.

    PubMed

    2014-05-30

    The Food and Drug Administration (FDA) is reclassifying nucleic acid-based in vitro diagnostic devices for the detection of Mycobacterium tuberculosis complex in respiratory specimens from class III (premarket approval) into class II (special controls). FDA is also issuing the special controls guideline entitled ''Class II Special Controls Guideline: Nucleic Acid-Based In Vitro Diagnostic Devices for the Detection of Mycobacterium tuberculosis Complex in Respiratory Specimens.'' These devices are intended to be used as an aid in the diagnosis of pulmonary tuberculosis.

  20. Luminescent cyclometallated iridium(III) complexes having acetylide ligands

    DOEpatents

    Thompson, Mark E.; Bossi, Alberto; Djurovich, Peter Ivan

    2014-09-02

    The present invention relates to phosphorescent (triplet-emitting) organometallic materials. The phosphorescent materials of the present invention comprise Ir(III)cyclometallated alkynyl complexes for use as triplet light-emitting materials. The Ir(III)cyclometallated alkynyl complexes comprise at least one cyclometallating ligand and at least one alkynyl ligand bonded to the iridium. Also provided is an organic light emitting device comprising an anode, a cathode and an emissive layer between the anode and the cathode, wherein the emissive layer comprises a Ir(III)cyclometallated alkynyl complex as a triplet emitting material.

  1. Modulation of active Cr(III) complexes by bath preparation to adjust Cr(III) electrodeposition

    NASA Astrophysics Data System (ADS)

    Li, Lei; Wang, Zhi; Wang, Ming-yong; Zhang, Yi

    2013-09-01

    The preparation process of the Cr(III) bath was studied based on a perspective of accelerating the formation of active Cr(III) complexes. The results of ultraviolet-visible absorption spectroscopy (UV-Vis) and electrodeposition showed that active Cr(III) complexes in the bath prepared at room temperature in several days were rare for depositing chromium. The increase of heating temperature, time, and pH value during the bath preparation promoted the formation of active Cr(III) complexes. The chromium deposition rate increased with the concentration of active Cr(III) complexes increasing. Increasing the heating temperature from 60 to 96°C, the chromium deposition rate increased from 0.40 to 0.71 μm/min. When the concentration of active Cr(III) complexes increased, the grain size of Cr coatings increased, and the carbon content of the coating decreased. It is deduced that Cr(H2O)4(OH)L2+ (L is an organic ligand, and its valence is omitted) is a primary active Cr(III) complex.

  2. Gold(III) complexes in medicinal chemistry.

    PubMed

    Maia, Pedro Ivo da Silva; Deflon, Victor M; Abram, Ulrich

    2014-09-01

    A number of gold(III) compounds has been designed with the objective of overcoming the disadvantages associated with the platinum-based drugs for cancer treatment. Compounds of a remarkable structural manifold show significant antiproliferative effects in vitro against a number of cancer cells, including cisplatin resistant ones. The target of most of them is, unlike that of cisplatin, not the DNA. Although the mechanisms of action displayed by the gold compounds in biological media are still under investigation, many studies show evidence that the cellular targets are mitochondria-based. Recent advances in gold(III) medicinal chemistry also recommend such compounds for other pharmacological applications such as the treatment of viral or parasitic diseases. The radioactive isotopes (198)Au and (199)Au present potential in radiotherapy.

  3. Complexation of Cm(III)/Eu(III) with Silicate in Basic Solutions

    SciTech Connect

    Wang, Zheming; Felmy, Andrew R; Xia, Yuanxian; Qafoku, Odeta; Yantasee, Wassana; Cho, Herman M

    2005-12-01

    The complexation of Cm(III) and Eu(III) with dissolved silica was studied by time resolved laser fluorescence spectroscopy (TRLFS) in basic solutions over a range of total silica concentrations and ionic strengths (NaNO3). In highly basic solutions, both the fluorescence spectra and lifetime data indicate the formation of Eu(III)/Cm(III) complexes with oligomeric silicates as well as hydroxide groups and/or nitrate in the presence of concentrated NaNO3. At high silica concentration the inner-sphere complexation caused the shift of the fluorescence spectral maximum for Cm(III)(aq) from 594 nm to up to 607 nm and a significant increase of the hypersensitive 5D0 → 7F2 band around 615 nm relative to the non-hypersensitive 5D0 → 7F1 band at 592 nm for Eu(III). At the same time, the fluorescence lifetime increased from 68 s to up to 202 s for Cm(III) in 0.1 M NaNO3 and from 115 s to 1.8 ms for Eu(III) in 3.0 M and 5.0 M NaNO3, consistent with the removal of 6 or more water molecules upon silicate complexation. Linear correlations between the spectral intensity of Cm(III) complexes and the concentrations of the dissolved silicates suggest that Cm(III) complexation with the silicate dimer, Si2O2(OH)22-, may play a role.

  4. Reversible FMN dissociation from Escherichia coli respiratory complex I.

    PubMed

    Holt, Peter J; Efremov, Rouslan G; Nakamaru-Ogiso, Eiko; Sazanov, Leonid A

    2016-11-01

    Respiratory complex I transfers electrons from NADH to quinone, utilizing the reaction energy to translocate protons across the membrane. It is a key enzyme of the respiratory chain of many prokaryotic and most eukaryotic organisms. The reversible NADH oxidation reaction is facilitated in complex I by non-covalently bound flavin mononucleotide (FMN). Here we report that the catalytic activity of E. coli complex I with artificial electron acceptors potassium ferricyanide (FeCy) and hexaamineruthenium (HAR) is significantly inhibited in the enzyme pre-reduced by NADH. Further, we demonstrate that the inhibition is caused by reversible dissociation of FMN. The binding constant (Kd) for FMN increases from the femto- or picomolar range in oxidized complex I to the nanomolar range in the NADH reduced enzyme, with an FMN dissociation time constant of ~5s. The oxidation state of complex I, rather than that of FMN, proved critical to the dissociation. Such dissociation is not observed with the T. thermophilus enzyme and our analysis suggests that the difference may be due to the unusually high redox potential of Fe-S cluster N1a in E. coli. It is possible that the enzyme attenuates ROS production in vivo by releasing FMN under highly reducing conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Deficiency of respiratory chain complex I in Hashimoto thyroiditis.

    PubMed

    Zimmermann, Franz A; Neureiter, Daniel; Feichtinger, René G; Trost, Andrea; Sperl, Wolfgang; Kofler, Barbara; Mayr, Johannes A

    2016-01-01

    Oncocytic cells (OCs) are characterized by an accumulation of mitochondria and their occurrence in the thyroid gland of patients with Hashimoto thyroiditis (HT) is well known. However, their properties and functional relevance are poorly understood. We investigated OC lesions (n=212) in the thyroid of 12 HT patients. Loss of complex I protein was observed in oncocytic lesions of each of the patients. In addition to isolated complex I deficiency, 25% of oncocytic lesions showed combined deficiency of complex I and IV. Thus, we demonstrate for the first time a defect of respiratory chain complex I in OCs of HT patients. Copyright © 2015 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

  6. Aerosol Phage Therapy Efficacy in Burkholderia cepacia Complex Respiratory Infections

    PubMed Central

    Semler, Diana D.; Goudie, Amanda D.; Finlay, Warren H.

    2014-01-01

    Phage therapy has been suggested as a potential treatment for highly antibiotic-resistant bacteria, such as the species of the Burkholderia cepacia complex (BCC). To address this hypothesis, experimental B. cenocepacia respiratory infections were established in mice using a nebulizer and a nose-only inhalation device. Following infection, the mice were treated with one of five B. cenocepacia-specific phages delivered as either an aerosol or intraperitoneal injection. The bacterial and phage titers within the lungs were assayed 2 days after treatment, and mice that received the aerosolized phage therapy demonstrated significant decreases in bacterial loads. Differences in phage activity were observed in vivo. Mice that received phage treatment by intraperitoneal injection did not demonstrate significantly reduced bacterial loads, although phage particles were isolated from their lung tissue. Based on these data, aerosol phage therapy appears to be an effective method for treating highly antibiotic-resistant bacterial respiratory infections, including those caused by BCC bacteria. PMID:24798268

  7. Aerosol phage therapy efficacy in Burkholderia cepacia complex respiratory infections.

    PubMed

    Semler, Diana D; Goudie, Amanda D; Finlay, Warren H; Dennis, Jonathan J

    2014-07-01

    Phage therapy has been suggested as a potential treatment for highly antibiotic-resistant bacteria, such as the species of the Burkholderia cepacia complex (BCC). To address this hypothesis, experimental B. cenocepacia respiratory infections were established in mice using a nebulizer and a nose-only inhalation device. Following infection, the mice were treated with one of five B. cenocepacia-specific phages delivered as either an aerosol or intraperitoneal injection. The bacterial and phage titers within the lungs were assayed 2 days after treatment, and mice that received the aerosolized phage therapy demonstrated significant decreases in bacterial loads. Differences in phage activity were observed in vivo. Mice that received phage treatment by intraperitoneal injection did not demonstrate significantly reduced bacterial loads, although phage particles were isolated from their lung tissue. Based on these data, aerosol phage therapy appears to be an effective method for treating highly antibiotic-resistant bacterial respiratory infections, including those caused by BCC bacteria.

  8. New Samarium(III), Gadolinium(III), and Dysprosium(III) Complexes of Coumarin-3-Carboxylic Acid as Antiproliferative Agents

    PubMed Central

    Kostova, Irena; Momekov, Georgi; Stancheva, Peya

    2007-01-01

    New complexes of samarium(III), gadolinium(III), and dysprosium(III) with coumarin-3-carboxylic acid (HCCA) were prepared by the reaction of the ligand with respective metal nitrates in ethanol. The structures of the final complexes were determined by means of physicochemical data, elemental analysis, IR and Raman spectra. The metal-ligand binding mode in the new Ln(III) complexes of coumarin-3-carboxylic acid was elucidated. The vibrational study gave evidence for bidentate coordination of CCA− to Ln(III) ions through the carbonylic oxygen and the carboxylic oxygen atoms. The complexes were tested for antiproliferative activitiy on the chronic myeloid leukemia-derived K-562, overexpressing the BCR-ABL fusion protein. Cytotoxicity towards tumor cells was determined for a broad concentration range. The samarium salt exerted a very weak antiproliferative effect on these cells. This is in contrast to the lanthanide complexes, especially samarium complex, which exhibited potent antiproliferative activity. The present study confirms our previous observations that the lanthanide complexes of coumarins exhibit antiproliferative activity towards K-562 cell line. PMID:18274603

  9. Synthesis and in vitro microbial evaluation of La(III), Ce(III), Sm(III) and Y(III) metal complexes of vitamin B6 drug

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Al-Azab, Fathi M.; Al-Maydama, Hussein M. A.; Amin, Ragab R.; Jamil, Yasmin M. S.

    2014-06-01

    Metal complexes of pyridoxine mono hydrochloride (vitamin B6) are prepared using La(III), Ce(III), Sm(III) and Y(III). The resulting complexes are investigated. Some physical properties, conductivity, analytical data and the composition of the four pyridoxine complexes are discussed. The elemental analysis shows that the formed complexes of La(III), Ce(III), Sm(III) and Y(III) with pyridoxine are of 1:2 (metal:PN) molar ratio. All the synthesized complexes are brown in color and possess high melting points. These complexes are partially soluble in hot methanol, dimethylsulfoxide and dimethylformamide and insoluble in water and some other organic solvents. Elemental analysis data, spectroscopic (IR, UV-vis. and florescence), effective magnetic moment in Bohr magnetons and the proton NMR suggest the structures. However, definite particle size is determined by invoking the X-ray powder diffraction and scanning electron microscopy data. The results obtained suggested that pyridoxine reacted with metal ions as a bidentate ligand through its phenolate oxygen and the oxygen of the adjacent group at the 4‧-position. The molar conductance measurements proved that the pyridoxine complexes are electrolytic in nature. The kinetic and thermodynamic parameters such as: Ea, ΔH*, ΔS* and ΔG* were estimated from the DTG curves. The antibacterial evaluation of the pyridoxine and their complexes were also performed against some gram positive, negative bacteria as well as fungi.

  10. Acute and Chronic Treatments with Quetiapine Increase Mitochondrial Respiratory Chain Complex Activity in the Rat Brain.

    PubMed

    Ignácio, Zuleide M; Réus, Gislaine Z; Abelaira, Helena M; Titus, Stephanie E; Carlessi, Anelise S; da Luz, Jaine R; Matias, Beatriz I; Bruchchen, Livia; Carvalho-Silva, Milena; Gomes, Lara M; Rebelo, Joyce; Streck, Emilio L; Quevedo, João

    2015-01-01

    Several studies have found that the molecular mechanisms of mitochondrial energy metabolism are impaired in major depressive disorder (MDD). Classic antidepressants and atypical antipsychotics can alter the function of enzymes involved in adenosine triphosphate (ATP) metabolism. Quetiapine is an atypical antipsychotic that, in addition to having a therapeutic benefit in treating MDD, appears to exert antioxidant and neuroprotective effects. Therefore, we aimed to evaluate the acute and chronic effects of quetiapine on the activity of enzyme complexes I to IV of the mitochondrial respiratory chain and creatine kinase (CK) in brain regions involved with MDD. After a single dose or serial injections over 14 days of quetiapine (20, 40, and 80 mg) were administered, isolates from the pre- frontal cortex, hippocampus, amygdala and nucleus accumbens were analyzed for enzyme activity levels. The enzyme activity varied according to the dose, brain region, and acute or chronic dosing protocols. In general, complexes I-III activity was increased, especially after acute administration. Acute administration also increased the activity of complex IV and CK in the amygdala while complex I was inhibited in the prefrontal cortex and nucleus accumbens. These results suggest that quetiapine produces an increase in respiratory chain complex activity, which may be underlying its efficacy against psychiatric disorders and neuronal damage.

  11. Respiratory complex I: 'steam engine' of the cell?

    PubMed

    Efremov, Rouslan G; Sazanov, Leonid A

    2011-08-01

    Complex I is the first enzyme of the respiratory chain and plays a central role in cellular energy production. It has been implicated in many human neurodegenerative diseases, as well as in ageing. One of the biggest membrane protein complexes, it is an L-shaped assembly consisting of hydrophilic and membrane domains. Previously, we have determined structures of the hydrophilic domain in several redox states. Last year was marked by fascinating breakthroughs in the understanding of the complete structure. We described the architecture of the membrane domain and of the entire bacterial complex I. X-ray analysis of the larger mitochondrial enzyme has also been published. The core subunits of the bacterial and mitochondrial enzymes have remarkably similar structures. The proposed mechanism of coupling between electron transfer and proton translocation involves long-range conformational changes, coordinated in part by a long α-helix, akin to the coupling rod of a steam engine.

  12. Exploring the ubiquinone binding cavity of respiratory complex I.

    PubMed

    Tocilescu, Maja A; Fendel, Uta; Zwicker, Klaus; Kerscher, Stefan; Brandt, Ulrich

    2007-10-05

    Proton pumping respiratory complex I is a major player in mitochondrial energy conversion. Yet little is known about the molecular mechanism of this large membrane protein complex. Understanding the details of ubiquinone reduction will be prerequisite for elucidating this mechanism. Based on a recently published partial structure of the bacterial enzyme, we scanned the proposed ubiquinone binding cavity of complex I by site-directed mutagenesis in the strictly aerobic yeast Yarrowia lipolytica. The observed changes in catalytic activity and inhibitor sensitivity followed a consistent pattern and allowed us to define three functionally important regions near the ubiquinone-reducing iron-sulfur cluster N2. We identified a likely entry path for the substrate ubiquinone and defined a region involved in inhibitor binding within the cavity. Finally, we were able to highlight a functionally critical structural motif in the active site that consisted of Tyr-144 in the 49-kDa subunit, surrounded by three conserved hydrophobic residues.

  13. Bimetallic Reductive Elimination from Dinuclear Pd(III) Complexes

    PubMed Central

    Powers, David C.; Benitez, Diego; Tkatchouk, Ekaterina; Goddard, William A.

    2010-01-01

    In 2009, we reported C–halogen reductive elimination reactions from dinuclear Pd(III) complexes and implicated dinuclear intermediates in Pd(OAc)2-catalyzed C–H oxidation chemistry. Herein, we report results of a thorough experimental and theoretical investigation of the mechanism of reductive elimination from such dinuclear Pd(III) complexes, which establish the role of each metal during reductive elimination. Our results implicate reductive elimination from a complex in which the dinuclear core is intact and suggest that redox synergy between both metals is responsible for the facile reductive elimination reactions observed. PMID:20858006

  14. Type III CRISPR complexes from Thermus thermophilus.

    PubMed

    Szychowska, Marta; Siwek, Wojciech; Pawolski, Damian; Kazrani, Asgar Abbas; Pyrc, Krzysztof; Bochtler, Matthias

    2016-01-01

    Pathogen-specific acquired immunity in bacteria is mediated by the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas systems. Thermus thermophilus strain HB8 contains CRISPR systems of several major subtypes (type I, IIIA and IIIB), and has become a widely studied model for CRISPR biology. We have selected two highly expressed CRISPR spacers, crRNA 2.1 and crRNA 2.2, and have enriched endogenous T. thermophilus proteins that co-purify with these crRNAs. Mass spectroscopy indicates that the chromatography protocol enriches predominantly Csm complex subunits, but also Cmr subunits. After several chromatographic steps, size exclusion chromatography indicated a molecular mass of the crRNA associated complex of 265±69 kDa. In agreement with earlier work, crRNAs of different lengths (containing the selected spacers) were observed. Most of these were completely lost when several T. thermophilus csm genes were ablated.

  15. Phosphorescence bioimaging using cyclometalated Ir(III) complexes.

    PubMed

    You, Youngmin

    2013-08-01

    Recent advances in the development of the phosphorescent Ir(III) complexes have made it possible to implement the phosphorescence modality in bioimaging applications. A variety of phosphorescent Ir(III) complexes have been synthesized and assessed in the context of in vitro and in vivo imaging, especially in subcellular organelle staining and the sensing of biologically important analytes. The examples presented here demonstrate that Ir(III) complexes provide attractive alternatives to fluorescent organic compounds in the construction of biolabels and biosensors. The complexes are particularly advantageous with respect to fluorescent compounds in their compatibility with time-gated bioimaging techniques that completely eliminate background signals due to autofluorescence. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Differential proteomic profiling unveils new molecular mechanisms associated with mitochondrial complex III deficiency

    PubMed Central

    Morán, María; López-Bernardo, Elia; Cadenas, Susana; Hidalgo, Beatriz; Sánchez, Ricardo; Seneca, Sara; Arenas, Joaquín; Martín, Miguel A.; Ugalde, Cristina

    2014-01-01

    We have analyzed the cellular pathways and metabolic adaptations that take place in primary skin fibroblasts from patients with mutations in BCS1L, a major genetic cause of mitochondrial complex III enzyme deficiency. Mutant fibroblasts exhibited low oxygen consumption rates and intracellular ATP levels, indicating that the main altered molecular event probably is a limited respiration-coupled ATP production through the OXPHOS system. Two-dimensional DIGE and MALDI-TOF/TOF mass spectrometry analyses unambiguously identified 39 proteins whose expression was significantly altered in complex III-deficient fibroblasts. Extensive statistical and cluster analyses revealed a protein profile characteristic for the BCS1L mutant fibroblasts that included alterations in energy metabolism, cell signaling and gene expression regulation, cytoskeleton formation and maintenance, and intracellular stress responses. The physiological validation of the predicted functional adaptations of human cultured fibroblasts to complex III deficiency confirmed the up-regulation of glycolytic enzyme activities and the accumulation of branched-chain among other amino acids, suggesting the activation of anaerobic glycolysis and cellular catabolic states, in particular protein catabolism, together with autophagy as adaptive responses to mitochondrial respiratory chain dysfunction and ATP deficiency. Our data point to an overall metabolic and genetic reprogramming that could contribute to explain the clinical manifestations of complex III deficiency in patients. PMID:25239759

  17. Sparkle/PM3 Parameters for the Modeling of Neodymium(III), Promethium(III), and Samarium(III) Complexes.

    PubMed

    Freire, Ricardo O; da Costa, Nivan B; Rocha, Gerd B; Simas, Alfredo M

    2007-07-01

    The Sparkle/PM3 model is extended to neodymium(III), promethium(III), and samarium(III) complexes. The unsigned mean error, for all Sparkle/PM3 interatomic distances between the trivalent lanthanide ion and the ligand atoms of the first sphere of coordination, is 0.074 Å for Nd(III); 0.057 Å for Pm(III); and 0.075 Å for Sm(III). These figures are similar to the Sparkle/AM1 ones of 0.076 Å, 0.059 Å, and 0.075 Å, respectively, indicating they are all comparable models. Moreover, their accuracy is similar to what can be obtained by present-day ab initio effective potential calculations on such lanthanide complexes. Hence, the choice of which model to utilize will depend on the assessment of the effect of either AM1 or PM3 on the quantum chemical description of the organic ligands. Finally, we present a preliminary attempt to verify the geometry prediction consistency of Sparkle/PM3. Since lanthanide complexes are usually flexible, we randomly generated 200 different input geometries for the samarium complex QIPQOV which were then fully optimized by Sparkle/PM3. A trend appeared in that, on average, the lower the total energy of the local minima found, the lower the unsigned mean errors, and the higher the accuracy of the model. These preliminary results do indicate that attempting to find, with Sparkle/PM3, a global minimum for the geometry of a given complex, with the understanding that it will tend to be closer to the experimental geometry, appears to be warranted. Therefore, the sparkle model is seemingly a trustworthy semiempirical quantum chemical model for the prediction of lanthanide complexes geometries.

  18. A well-defined terminal vanadium(III) oxo complex.

    PubMed

    King, Amanda E; Nippe, Michael; Atanasov, Mihail; Chantarojsiri, Teera; Wray, Curtis A; Bill, Eckhard; Neese, Frank; Long, Jeffrey R; Chang, Christopher J

    2014-11-03

    The ubiquity of vanadium oxo complexes in the V+ and IV+ oxidation states has contributed to a comprehensive understanding of their electronic structure and reactivity. However, despite being predicted to be stable by ligand-field theory, the isolation and characterization of a well-defined terminal mononuclear vanadium(III) oxo complex has remained elusive. We present the synthesis and characterization of a unique terminal mononuclear vanadium(III) oxo species supported by the pentadentate polypyridyl ligand 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine (PY5Me2). Exposure of [V(II)(NCCH3)(PY5Me2)](2+) (1) to either dioxygen or selected O-atom-transfer reagents yields [V(IV)(O)(PY5Me2)](2+) (2). The metal-centered one-electron reduction of this vanadium(IV) oxo complex furnishes a stable, diamagnetic [V(III)(O)(PY5Me2)](+) (3) species. The vanadium(III) oxo species is unreactive toward H- and O-atom transfer but readily reacts with protons to form a putative vanadium hydroxo complex. Computational results predict that further one-electron reduction of the vanadium(III) oxo species will result in ligand-based reduction, even though pyridine is generally considered to be a poor π-accepting ligand. These results have implications for future efforts toward low-valent vanadyl chemistry, particularly with regard to the isolation and study of formal vanadium(II) oxo species.

  19. Lanthanum(III) and praseodymium(III) complexes with isatin thiosemicarbazones.

    PubMed

    Rai, Anita; Sengupta, Soumitra K; Pandey, Om P

    2005-09-01

    Ten new lanthanum(III) and praseodymium(III) complexes of the general formula Na[La(L)2H2O] (Ln=La(III) or Pr(III); LH2=thiosemicarbazones) derived from the condensation of isatin with 4-phenyl thiosemicarbazide, 4-(4-chlorophenyl) thiosemicarbazide, 4-(2-nitrophenyl) thiosemicarbazide, 4-(2-bromophenyl) thiosemicarbazide and 4-(2-methylphenyl) thiosemicarbazide, have been synthesized in methanol in presence of sodium hydroxide. The XRD spectra of the complexes were monitored to verify complex formation. The complexes have also been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H and 13C NMR spectral studies. Thermal studies of these complexes have been carried out in the temperature range 25-800 degrees C using TG, DTG and DTA techniques. All these complexes decompose gradually with the formation of Ln2O3 as the end product. The Judd-ofelt intensity parameter, oscillator strength, transition probability, stimulated emission cross section for different transitions of Pr3+ for 4-phenyl thiosemicarbazones have been calculated.

  20. Mitochondrial dysfunction in the hypertensive rat brain: respiratory complexes exhibit assembly defects in hypertension.

    PubMed

    Lopez-Campistrous, Ana; Hao, Li; Xiang, Wang; Ton, Dong; Semchuk, Paul; Sander, Joerg; Ellison, Michael J; Fernandez-Patron, Carlos

    2008-02-01

    The central nervous system plays a critical role in the normal control of arterial blood pressure and in its elevation in virtually all forms of hypertension. Mitochondrial dysfunction has been increasingly associated with the development of hypertension. Therefore, we examined whether mitochondrial dysfunction occurs in the brain in hypertension and characterized it at the molecular scale. Mitochondria from whole brain and brain stem from 12-week-old spontaneously hypertensive rats with elevated blood pressure (190+/-5 mm Hg) were compared against those from age-matched normotensive (134+/-7 mm Hg) Wistar Kyoto rats (n=4 in each group). Global differential analysis using 2D electrophoresis followed by tandem mass spectrometry-based protein identification suggested a downregulation of enzymes involved in cellular energetics in hypertension. Targeted differential analysis of mitochondrial respiratory complexes using the classical blue-native SDS-PAGE/Western method and a complementary combination of sucrose-gradient ultracentrifugation/tandem mass spectrometry revealed previously unknown assembly defects in complexes I, III, IV, and V in hypertension. Interestingly, targeted examination of the brain stem, a regulator of cardiovascular homeostasis and systemic blood pressure, further showed the occurrence of mitochondrial complex I dysfunction, elevated reactive oxygen species production, decreased ATP synthesis, and impaired respiration in hypertension. Our findings suggest that in already-hypertensive spontaneously hypertensive rats, the brain respiratory complexes exhibit previously unknown assembly defects. These defects impair the function of the mitochondrial respiratory chain. This mitochondrial dysfunction localizes to the brain stem and is, therefore, likely to contribute to the development, as well as to pathophysiological complications, of hypertension.

  1. Exploring the inhibitor binding pocket of respiratory complex I.

    PubMed

    Fendel, Uta; Tocilescu, Maja A; Kerscher, Stefan; Brandt, Ulrich

    2008-01-01

    Numerous hydrophobic and amphipathic compounds including several detergents are known to inhibit the ubiquinone reductase reaction of respiratory chain complex I (proton pumping NADH:ubiquinone oxidoreductase). Guided by the X-ray structure of the peripheral arm of complex I from Thermus thermophilus we have generated a large collection of site-directed mutants in the yeast Yarrowia lipolytica targeting the proposed ubiquinone and inhibitor binding pocket of this huge multiprotein complex at the interface of the 49-kDa and PSST subunits. We could identify a number of residues where mutations changed I(50) values for representatives from all three groups of hydrophobic inhibitors. Many mutations around the domain of the 49-kDa subunit that is homologous to the [NiFe] centre binding region of hydrogenase conferred resistance to DQA (class I/type A) and rotenone (class II/type B) indicating a wider overlap of the binding sites for these two types of inhibitors. In contrast, a region near iron-sulfur cluster N2, where the binding of the n-alkyl-polyoxyethylene-ether detergent C(12)E(8) (type C) was exclusively affected, appeared comparably well separated. Taken together, our data provide structure-based support for the presence of distinct but overlapping binding sites for hydrophobic inhibitors possibly extending into the ubiquinone reduction site of mitochondrial complex I.

  2. CK2 involvement in ESCRT-III complex phosphorylation.

    PubMed

    Salvi, Mauro; Raiborg, Camilla; Hanson, Phyllis I; Campsteijn, Coen; Stenmark, Harald; Pinna, Lorenzo A

    2014-03-01

    The multivesicular body (MVB) sorting pathway is a mechanism for delivering transmembrane proteins into the lumen of the lysosome for degradation. ESCRT-III is the final complex in the pathway that assembles on endosomes and executes membrane scission of intraluminal vesicles. In addition, proteins of this complex are involved in other topologically similar processes such as cytokinesis, virus egress and autophagy. Here we show that protein kinase CK2α is involved in the phosphorylation of the ESCRT-III subunits CHMP3 and CHMP2B, as well as of VPS4B/SKD1, an ATPase that mediates ESCRT-III disassembly. This phosphorylation is observed both in vitro and in cells. While we do not observe recruitment of CK2α to endosomes, we demonstrate the localization of CK2α to midbodies during cytokinesis. Phosphomimetic and non-phosphorylatable mutants of ESCRT-III proteins can still bind endosomes and localize to midbodies, indicating that CK2α does not regulate ESCRT-III localization. Finally, we analyzed two cellular functions where CHMP3, CHMP2B and VPS4 are known to be involved, epidermal growth factor degradation and cytokinetic abscission. We demonstrate that the former is impaired by CK2α downregulation whereas the latter is not affected. Taken together, our results indicate that CK2α regulates the function of ESCRT-III proteins in MVB sorting.

  3. Statin-Induced Myopathy Is Associated with Mitochondrial Complex III Inhibition.

    PubMed

    Schirris, Tom J J; Renkema, G Herma; Ritschel, Tina; Voermans, Nicol C; Bilos, Albert; van Engelen, Baziel G M; Brandt, Ulrich; Koopman, Werner J H; Beyrath, Julien D; Rodenburg, Richard J; Willems, Peter H G M; Smeitink, Jan A M; Russel, Frans G M

    2015-09-01

    Cholesterol-lowering statins effectively reduce the risk of major cardiovascular events. Myopathy is the most important adverse effect, but its underlying mechanism remains enigmatic. In C2C12 myoblasts, several statin lactones reduced respiratory capacity and appeared to be strong inhibitors of mitochondrial complex III (CIII) activity, up to 84% inhibition. The lactones were in general three times more potent inducers of cytotoxicity than their corresponding acid forms. The Qo binding site of CIII was identified as off-target of the statin lactones. These findings could be confirmed in muscle tissue of patients suffering from statin-induced myopathies, in which CIII enzyme activity was reduced by 18%. Respiratory inhibition in C2C12 myoblasts could be attenuated by convergent electron flow into CIII, restoring respiration up to 89% of control. In conclusion, CIII inhibition was identified as a potential off-target mechanism associated with statin-induced myopathies.

  4. Gadolinium(III) complexes as MRI contrast agents: ligand design and properties of the complexes.

    PubMed

    Hermann, Petr; Kotek, Jan; Kubícek, Vojtech; Lukes, Ivan

    2008-06-21

    Magnetic resonance imaging is a commonly used diagnostic method in medicinal practice as well as in biological and preclinical research. Contrast agents (CAs), which are often applied are mostly based on Gd(III) complexes. In this paper, the ligand types and structures of their complexes on one side and a set of the physico-chemical parameters governing properties of the CAs on the other side are discussed. The solid-state structures of lanthanide(III) complexes of open-chain and macrocyclic ligands and their structural features are compared. Examples of tuning of ligand structures to alter the relaxometric properties of gadolinium(III) complexes as a number of coordinated water molecules, their residence time (exchange rate) or reorientation time of the complexes are given. Influence of the structural changes of the ligands on thermodynamic stability and kinetic inertness/lability of their lanthanide(III) complexes is discussed.

  5. Photophysics of Fe(III)-tartrate and Fe(III)-citrate complexes in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Pozdnyakov, Ivan P.; Kolomeets, Alexander V.; Plyusnin, Victor F.; Melnikov, Alexey A.; Kompanets, Victor O.; Chekalin, Sergey V.; Tkachenko, Nikolai; Lemmetyinen, Helge

    2012-03-01

    Femtosecond pump-probe spectroscopy was used to determine the photophysical processes of Fe(III) complexes with citric and tartaric acids ([Fe(Cit)] and [Fe(tart)]+) in aqueous solutions. The excitation of the complexes in the charge transfer bands is followed by formation of an intermediate absorbance decaying with two characteristic times. The shorter time constant (0.2, 0.4 ps) is ascribed to vibrational cooling and solvent relaxation of Frank-Condon excited state of corresponding complex and the second time constant (1.4, 40 ps) is assigned to superposition of internal conversion to the ground state and formation of the long-lived Fe(II) radical complex. The competition of these processes determines the quantum yield of photolysis of Fe(III)-carboxylates.

  6. A Ruthenium(III)-Oxyl Complex Bearing Strong Radical Character.

    PubMed

    Shimoyama, Yoshihiro; Ishizuka, Tomoya; Kotani, Hiroaki; Shiota, Yoshihito; Yoshizawa, Kazunari; Mieda, Kaoru; Ogura, Takashi; Okajima, Toshihiro; Nozawa, Shunsuke; Kojima, Takahiko

    2016-11-02

    Proton-coupled electron-transfer oxidation of a Ru(II) -OH2 complex, having an N-heterocyclic carbene ligand, gives a Ru(III) -O(.) species, which has an electronically equivalent structure of the Ru(IV) =O species, in an acidic aqueous solution. The Ru(III) -O(.) complex was characterized by spectroscopic methods and DFT calculations. The oxidation state of the Ru center was shown to be close to +3; the Ru-O bond showed a lower-energy Raman scattering at 732 cm(-1) and the Ru-O bond length was estimated to be 1.77(1) Å. The Ru(III) -O(.) complex exhibits high reactivity in substrate oxidation under catalytic conditions; particularly, benzaldehyde and the derivatives are oxidized to the corresponding benzoic acid through C-H abstraction from the formyl group by the Ru(III) -O(.) complex bearing a strong radical character as the active species. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Assessment of Fe(III) and Eu(III) complexation by silicate in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Patten, James T.; Byrne, Robert H.

    2017-04-01

    Prior investigations of Eu3+ complexation by silicate have led to predictions that rare earth silicate complexes (REESiO(OH)32+) are the dominant species of REEs in deep waters of the Atlantic and Pacific Oceans. The proposed importance of REE-silicate complexes has been used as a foundation to explain oceanic REE profiles. In the present work, we examine the significance of rare earth element complexation by silicate ions. As one fundamental means of assessing prior depictions of REE-silicate formation constant behavior, our work examines the comparative stability constant behavior of Eu(III) and Fe(III). Plots of Eu(III) complexation constants against Fe(III) formation constants, in conjunction with experimental determinations of FeSiO(OH)32+ formation constants, indicate that previously published EuSiO(OH)32+ formation constants are substantially overestimated. Assessment of prior EuSiO(OH)32+ formation constant determinations reveals that results obtained in the presence and absence of silicic acid polymerization are inconsistent. Much larger EuSiO(OH)32+ formation constants are obtained in the presence of polymeric silica. Reanalysis of complexation results obtained under conditions of minimal silicate polymerization leads to a EuSiO(OH)32+ formation constant that is smaller than previously published estimates by as much as a factor of ∼25. The dramatically reduced magnitude of Siβ1(Eu) relative to previously published results indicates that the role of silicate complexation in oceanic REE cycling is much less significant than previously proposed. The spectrophotometric investigations of FeSiO(OH)32+ formation in the present study yield the first characterization of FeSiO(OH)32+ formation constant behavior as a function of ionic strength:

  8. Does As(III) interact with Fe(II), Fe(III) and organic matter through ternary complexes?

    PubMed

    Catrouillet, Charlotte; Davranche, Mélanie; Dia, Aline; Bouhnik-Le Coz, Martine; Demangeat, Edwige; Gruau, Gérard

    2016-05-15

    Up until now, only a small number of studies have been dedicated to the binding processes of As(III) with organic matter (OM) via ionic Fe(III) bridges; none was interested in Fe (II). Complexation isotherms were carried out with As(III), Fe(II) or Fe(III) and Leonardite humic acid (HA). Although PHREEQC/Model VI, implemented with OM thiol groups, reproduced the experimental datasets with Fe(III), the poor fit between the experimental and modeled Fe(II) data suggested another binding mechanism for As(III) to OM. PHREEQC/Model VI was modified to take various possible As(III)-Fe(II)-OM ternary complex conformations into account. The complexation of As(III) as a mononuclear bidentate complex to a bidentate Fe(II)-HA complex was evidenced. However, the model needed to be improved since the distribution of the bidentate sites appeared to be unrealistic with regards to the published XAS data. In the presence of Fe(III), As(III) was bound to thiol groups which are more competitive with regards to the low density of formed Fe(III)-HA complexes. Based on the new data and previously published results, we propose a general scheme describing the various As(III)-Fe-MO complexes that are able to form in Fe and OM-rich waters.

  9. Respiratory chain complex I deficiency caused by mitochondrial DNA mutations

    PubMed Central

    Swalwell, Helen; Kirby, Denise M; Blakely, Emma L; Mitchell, Anna; Salemi, Renato; Sugiana, Canny; Compton, Alison G; Tucker, Elena J; Ke, Bi-Xia; Lamont, Phillipa J; Turnbull, Douglass M; McFarland, Robert; Taylor, Robert W; Thorburn, David R

    2011-01-01

    Defects of the mitochondrial respiratory chain are associated with a diverse spectrum of clinical phenotypes, and may be caused by mutations in either the nuclear or the mitochondrial genome (mitochondrial DNA (mtDNA)). Isolated complex I deficiency is the most common enzyme defect in mitochondrial disorders, particularly in children in whom family history is often consistent with sporadic or autosomal recessive inheritance, implicating a nuclear genetic cause. In contrast, although a number of recurrent, pathogenic mtDNA mutations have been described, historically, these have been perceived as rare causes of paediatric complex I deficiency. We reviewed the clinical and genetic findings in a large cohort of 109 paediatric patients with isolated complex I deficiency from 101 families. Pathogenic mtDNA mutations were found in 29 of 101 probands (29%), 21 in MTND subunit genes and 8 in mtDNA tRNA genes. Nuclear gene defects were inferred in 38 of 101 (38%) probands based on cell hybrid studies, mtDNA sequencing or mutation analysis (nuclear gene mutations were identified in 22 probands). Leigh or Leigh-like disease was the most common clinical presentation in both mtDNA and nuclear genetic defects. The median age at onset was higher in mtDNA patients (12 months) than in patients with a nuclear gene defect (3 months). However, considerable overlap existed, with onset varying from 0 to >60 months in both groups. Our findings confirm that pathogenic mtDNA mutations are a significant cause of complex I deficiency in children. In the absence of parental consanguinity, we recommend whole mitochondrial genome sequencing as a key approach to elucidate the underlying molecular genetic abnormality. PMID:21364701

  10. Synthesis and structural characterization of new dithiocarbamate complexes from Sb(III) and Bi(III)

    SciTech Connect

    Jamaluddin, Nur Amirah; Baba, Ibrahim

    2013-11-27

    Twenty new antimony and bismuth dithiocarbamate complexes which employed ten different type of amines have been successfully synthesized. The synthesized complexes with metal to dithiocarbamate ratio at 1:3. Elemental analysis of the complexes gave the general formula of MCl[S{sub 2}CNR’R”]{sub 2} where M = Sb(III), Bi(III); R’ = methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl; R” = ethanol, methyl, ethyl, propyl, isopropyl, cyclohexyl, benzyl. The complexes were analysed by IR and NMR spectroscopy. The crystal structure of five-coordinated antimony (III) complex have been determined by X-ray single crystal diffraction. Single crystal X-ray diffraction studies on SbCl[S{sub 2}CN(C{sub 4}H{sub 9})(C{sub 2}H{sub 5})]{sub 2} adopted a triclinic system with a space group P1 with a = 10.0141(8) Å, b = 10.1394(7) Å, c = 11.8665(9) Å, α = 67.960°, β =87.616°, γ = 80.172°.

  11. Detection of Lungs Status Using Morphological Complexities of Respiratory Sounds

    PubMed Central

    Bhattacharya, Parthasarathi

    2014-01-01

    Traditionally, the clinical diagnosis of a respiratory disease is made from a careful clinical examination including chest auscultation. Objective analysis and automatic interpretation of the lung sound based on its physical characters are strongly warranted to assist clinical practice. In this paper, a new method is proposed to distinguish between the normal and the abnormal subjects using the morphological complexities of the lung sound signals. The morphological embedded complexities used in these experiments have been calculated in terms of texture information (lacunarity), irregularity index (sample entropy), third order moment (skewness), and fourth order moment (Kurtosis). These features are extracted from a mixed data set of 10 normal and 20 abnormal subjects and are analyzed using two different classifiers: extreme learning machine (ELM) and support vector machine (SVM) network. The results are obtained using 5-fold cross-validation. The performance of the proposed method is compared with a wavelet analysis based method. The developed algorithm gives a better accuracy of 92.86% and sensitivity of 86.30% and specificity of 86.90% for a composite feature vector of four morphological indices. PMID:24688364

  12. Acid induced acetylacetonato replacement in biscyclometalated iridium(III) complexes.

    PubMed

    Li, Yanfang; Liu, Yang; Zhou, Ming

    2012-04-07

    Biscyclometalated iridium(III) complexes with an ancillary acetylacetone ligand, Ir(L)(2)(acac), (L = 2-(benzo[b]thiophen-2-yl)pyridine (btp), 1-phenylisoquinoline (piq), 2-phenylbenzothiazole (bt), 2-phenylpyridine (ppy), acac = deprotonated acetylacetone), demonstrate spectroscopic changes in their UV-Vis absorption and luminescent emission under acidic conditions. Such changes were found to be the same as those observed when certain mercury salts exist in the systems. Because some iridium(III) complexes have sulfur-containing ligands (i.e., btp and bt), a question was then raised as for whether or not the spectroscopic changes are associated with the specific affinity of Hg(2+) to the sulfur atom. Extensive studies performed in this work unambiguously proved that the observed spectroscopic changes were solely the results of the acid induced departure of acac and the follow-up coordination of solvent acetonitrile to the iridium(III) center and that the generally anticipated Hg(2+)-S affinity and its effect on the photophysical properties of iridium(III) luminophores did not play a role.

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

    PubMed

    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.

  14. Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures

    SciTech Connect

    Tait, C.D.; Janecky, D.R.; Clark, D.L.; Bennett, P.C.

    1992-05-01

    To add to our understanding of the weathering of rocks in organic rich environments such as sedimentary brines and oil field waters, we have examined the temperature dependent complexation of aluminum with oxalate. Raman vibrational studies show that even the association constant for the highly charged Al(ox){sub 3}{sup 3{minus}} unexpectedly increases with moderate temperature increases to 80{degrees}C. To evaluate the potential importance of these Al-oxalate species in complex natural systems, temperature dependent competition experiments Fe(III) and Al(III) for oxalate have been initiated. Similar to aluminum, ferric oxalates show increases in association constants at higher temperatures. In competition experiments, the first association constant for Fe(ox){sup +} increases faster than that for Al(ox){sup +} to 90{degrees}C.

  15. Oxalate complexation with aluminum(III) and iron(III) at moderately elevated temperatures

    SciTech Connect

    Tait, C.D.; Janecky, D.R.; Clark, D.L. ); Bennett, P.C. . Dept. of Geological Sciences)

    1992-01-01

    To add to our understanding of the weathering of rocks in organic rich environments such as sedimentary brines and oil field waters, we have examined the temperature dependent complexation of aluminum with oxalate. Raman vibrational studies show that even the association constant for the highly charged Al(ox){sub 3}{sup 3{minus}} unexpectedly increases with moderate temperature increases to 80{degrees}C. To evaluate the potential importance of these Al-oxalate species in complex natural systems, temperature dependent competition experiments Fe(III) and Al(III) for oxalate have been initiated. Similar to aluminum, ferric oxalates show increases in association constants at higher temperatures. In competition experiments, the first association constant for Fe(ox){sup +} increases faster than that for Al(ox){sup +} to 90{degrees}C.

  16. Ketones prevent synaptic dysfunction induced by mitochondrial respiratory complex inhibitors

    PubMed Central

    Kim, Do Young; Vallejo, Johana; Rho, Jong M

    2010-01-01

    Abstract Ketones have previously shown beneficial effects in models of neurodegenerative disorders, particularly against associated mitochondrial dysfunction and cognitive impairment. However, evidence of a synaptic protective effect of ketones remains lacking. We tested the effects of ketones on synaptic impairment induced by mitochondrial respiratory complex (MRC) inhibitors using electrophysiological, reactive oxygen species (ROS) imaging and biochemical techniques. MRC inhibitors dose-dependently suppressed both population spike (PS) and field potential amplitudes in the CA1 hippocampus. Pre-treatment with ketones strongly prevented changes in the PS, whereas partial protection was seen in the field potential. Rotenone (Rot; 100 nmol/L), a MRC I inhibitor, suppressed synaptic function without altering ROS levels and PS depression by Rot was unaffected by antioxidants. In contrast, antioxidant-induced PS recovery against the MRC II inhibitor 3-nitropropionic acid (3-NP; 1 mmol/L) was similar to the synaptic protective effects of ketones. Ketones also suppressed ROS generation induced by 3-NP. Finally, ketones reversed the decreases in ATP levels caused by Rot and 3-NP. In summary, our data demonstrate that ketones can preserve synaptic function in CA1 hippocampus induced by MRC dysfunction, likely through an antioxidant action and enhanced ATP generation. PMID:20374433

  17. Quantum Electron Tunneling in Respiratory Complex I1

    PubMed Central

    Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

    2014-01-01

    We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. One-electron tunneling approximation is found to hold in electron tunneling between the anti-ferromagnetic binuclear and tetranuclear Fe/S clusters with moderate induced polarization of the core electrons. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A distinct signature of the wave properties of electrons is observed as quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included are in good agreement with a reported phenomenological relation. PMID:21495666

  18. Luminescent iridium(III) complexes as novel protein staining agents.

    PubMed

    Jia, Junli; Fei, Hao; Zhou, Ming

    2012-05-01

    This article reports a new class of luminescent metal complexes, biscyclometalated iridium(III) complexes with an ancillary bathophenanthroline disulfonate ligand, for staining protein bands that are separated by electrophoresis. The performances of these novel staining agents have been studied in comparison with tris(bathophenanthroline disulfonate) ruthenium(II) tetrasodium salt (i.e. RuBPS) using a commercially available imaging system. The staining agents showed different limits of detection, linear dynamic ranges, and protein-to-protein variations. The overall performances of all three stains were found to be better than or equivalent to RuBPS under the experimental conditions.

  19. Cardiac mitochondrial matrix and respiratory complex protein phosphorylation

    PubMed Central

    Covian, Raul

    2012-01-01

    It has become appreciated over the last several years that protein phosphorylation within the cardiac mitochondrial matrix and respiratory complexes is extensive. Given the importance of oxidative phosphorylation and the balance of energy metabolism in the heart, the potential regulatory effect of these classical signaling events on mitochondrial function is of interest. However, the functional impact of protein phosphorylation and the kinase/phosphatase system responsible for it are relatively unknown. Exceptions include the well-characterized pyruvate dehydrogenase and branched chain α-ketoacid dehydrogenase regulatory system. The first task of this review is to update the current status of protein phosphorylation detection primarily in the matrix and evaluate evidence linking these events with enzymatic function or protein processing. To manage the scope of this effort, we have focused on the pathways involved in energy metabolism. The high sensitivity of modern methods of detecting protein phosphorylation and the low specificity of many kinases suggests that detection of protein phosphorylation sites without information on the mole fraction of phosphorylation is difficult to interpret, especially in metabolic enzymes, and is likely irrelevant to function. However, several systems including protein translocation, adenine nucleotide translocase, cytochrome c, and complex IV protein phosphorylation have been well correlated with enzymatic function along with the classical dehydrogenase systems. The second task is to review the current understanding of the kinase/phosphatase system within the matrix. Though it is clear that protein phosphorylation occurs within the matrix, based on 32P incorporation and quantitative mass spectrometry measures, the kinase/phosphatase system responsible for this process is ill-defined. An argument is presented that remnants of the much more labile bacterial protein phosphoryl transfer system may be present in the matrix and that the

  20. The electronic spectra of mu-peroxodicobalt(III) complexes

    NASA Technical Reports Server (NTRS)

    Miskowski, Vincent M.

    1987-01-01

    Problems found in the determination of the electronic spectra of mu-peroxodicobalt(III) complexes are considered, and the common formation of different mu-peroxocomplexes upon oxygenation of Co(II)-ligand solutions is discussed. Three classes of spectra have been identified: (1) planar single bridged complexes; (2) nonplanar single-bridged complexes with a dihedral angle near 145 deg; and (3) dibridged mu-OH(-),O2(2-) complexes with a dihedral angle near 60 deg. All of the peroxide ligand-to-metal charge-transfer spectra are found to be consistent with a simple model that assumes a sinusoidal dependence of pi-asterisk O2(2-) energies and sigma-overlaps upon the dihedral angle.

  1. Acute Carnosine Administration Increases Respiratory Chain Complexes and Citric Acid Cycle Enzyme Activities in Cerebral Cortex of Young Rats.

    PubMed

    Macedo, Levy W; Cararo, José H; Maravai, Soliany G; Gonçalves, Cinara L; Oliveira, Giovanna M T; Kist, Luiza W; Guerra Martinez, Camila; Kurtenbach, Eleonora; Bogo, Maurício R; Hipkiss, Alan R; Streck, Emilio L; Schuck, Patrícia F; Ferreira, Gustavo C

    2016-10-01

    Carnosine (β-alanyl-L-histidine) is an imidazole dipeptide synthesized in excitable tissues of many animals, whose biochemical properties include carbonyl scavenger, anti-oxidant, bivalent metal ion chelator, proton buffer, and immunomodulating agent, although its precise physiological role(s) in skeletal muscle and brain tissues in vivo remain unclear. The aim of the present study was to investigate the in vivo effects of acute carnosine administration on various aspects of brain bioenergetics of young Wistar rats. The activity of mitochondrial enzymes in cerebral cortex was assessed using a spectrophotometer, and it was found that there was an increase in the activities of complexes I-III and II-III and succinate dehydrogenase in carnosine-treated rats, as compared to vehicle-treated animals. However, quantitative real-time RT-PCR (RT-qPCR) data on mRNA levels of mitochondrial biogenesis-related proteins (nuclear respiratory factor 1 (Nrf1), peroxisome proliferator-activated receptor-γ coactivator 1-α (Ppargc1α), and mitochondrial transcription factor A (Tfam)) were not altered significantly and therefore suggest that short-term carnosine administration does not affect mitochondrial biogenesis. It was in agreement with the finding that immunocontent of respiratory chain complexes was not altered in animals receiving carnosine. These observations indicate that acute carnosine administration increases the respiratory chain and citric acid cycle enzyme activities in cerebral cortex of young rats, substantiating, at least in part, a neuroprotector effect assigned to carnosine against oxidative-driven disorders.

  2. Complexation and molecular modeling studies of europium(III)-gallic acid-amino acid complexes.

    PubMed

    Taha, Mohamed; Khan, Imran; Coutinho, João A P

    2016-04-01

    With many metal-based drugs extensively used today in the treatment of cancer, attention has focused on the development of new coordination compounds with antitumor activity with europium(III) complexes recently introduced as novel anticancer drugs. The aim of this work is to design new Eu(III) complexes with gallic acid, an antioxida'nt phenolic compound. Gallic acid was chosen because it shows anticancer activity without harming health cells. As antioxidant, it helps to protect human cells against oxidative damage that implicated in DNA damage, cancer, and accelerated cell aging. In this work, the formation of binary and ternary complexes of Eu(III) with gallic acid, primary ligand, and amino acids alanine, leucine, isoleucine, and tryptophan was studied by glass electrode potentiometry in aqueous solution containing 0.1M NaNO3 at (298.2 ± 0.1) K. Their overall stability constants were evaluated and the concentration distributions of the complex species in solution were calculated. The protonation constants of gallic acid and amino acids were also determined at our experimental conditions and compared with those predicted by using conductor-like screening model for realistic solvation (COSMO-RS) model. The geometries of Eu(III)-gallic acid complexes were characterized by the density functional theory (DFT). The spectroscopic UV-visible and photoluminescence measurements are carried out to confirm the formation of Eu(III)-gallic acid complexes in aqueous solutions.

  3. Managing complex respiratory patients in the community: an evaluation of a pilot integrated respiratory care service

    PubMed Central

    Gillett, K; Lippiett, K; Astles, C; Longstaff, J; Orlando, R; Lin, S X; Powell, A; Roberts, C; Chauhan, A J; Thomas, M; Wilkinson, T M

    2016-01-01

    Introduction In the UK, there is significant variation in respiratory care and outcomes. An integrated approach to the management of high-risk respiratory patients, incorporating specialist and primary care teams' expertise, is the basis for new integrated respiratory services designed to reduce this variation; however, this model needs evaluating. Methods To evaluate an integrated service managing high-risk respiratory patients, electronic searches for patients with asthma and chronic obstructive pulmonary disease at risk of poor outcomes were performed in two general practitioner (GP) practices in a local service-development initiative. Patients were reviewed at joint clinics by primary and secondary care professionals. GPs also nominated patients for inclusion. Reviews were delivered to best standards of care including assessments of diagnosis, control, spirometry, self-management, education, medication, inhaler technique and smoking cessation support. Follow-up of routine clinical data collected at 9-months postclinic were compared with seasonally matched 9-months prior to integrated review. Results 82 patients were identified, 55 attended. 13 (23.6%) had their primary diagnosis changed. In comparison with the seasonally adjusted baseline period, in the 9-month follow-up there was an increase in inhaled corticosteroid prescriptions of 23.3%, a reduction in short-acting β2-agonist prescription of 33.3%, a reduction in acute respiratory exacerbations of 67.6%, in unscheduled GP surgery visits of 53.3% and acute respiratory hospital admissions reduced from 3 to 0. Only 4 patients (7.3%) required referral to secondary care. Health economic evaluation showed respiratory-related costs per patient reduced by £231.86. Conclusions Patients with respiratory disease in this region at risk of suboptimal outcomes identified proactively and managed by an integrated team improved outcomes without the need for hospital referral. PMID:28074134

  4. Cyclometalated iridium(III) complexes with deoxyribose substituents.

    PubMed

    Maity, Ayan; Choi, Jung-Suk; Teets, Thomas S; Deligonul, Nihal; Berdis, Anthony J; Gray, Thomas G

    2013-11-18

    Fundamental study of enzymatic nucleoside transport suffers for lack of optical probes that can be tracked noninvasively. Nucleoside transporters are integral membrane glycoproteins that mediate the salvage of nucleosides and their passage across cell membranes. The substrate recognition site is the deoxyribose sugar, often with little distinction among nucleobases. Reported here are nucleoside analogues in which emissive, cyclometalated iridium(III) complexes are "clicked" to C-1 of deoxyribose in place of canonical nucleobases. The resulting complexes show visible luminescence at room temperature and 77 K with microsecond-length triplet lifetimes. A representative complex is crystallographically characterized. Transport and luminescence are demonstrated in cultured human carcinoma (KB3-1) cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Ubisemiquinone is the electron donor for superoxide formation by complex III of heart mitochondria.

    PubMed

    Turrens, J F; Alexandre, A; Lehninger, A L

    1985-03-01

    Much evidence indicates that superoxide is generated from O2 in a cyanide-sensitive reaction involving a reduced component of complex III of the mitochondrial respiratory chain, particularly when antimycin A is present. Although it is generally believed that ubisemiquinone is the electron donor to O2, little experimental evidence supporting this view has been reported. Experiments with succinate as electron donor in the presence of antimycin A in intact rat heart mitochondria, which contain much superoxide dismutase but little catalase, showed that myxothiazol, which inhibits reduction of the Rieske iron-sulfur center, prevented formation of hydrogen peroxide, determined spectrophotometrically as the H2O2-peroxidase complex. Similarly, depletion of the mitochondria of their cytochrome c also inhibited formation of H2O2, which was restored by addition of cytochrome c. These observations indicate that factors preventing the formation of ubisemiquinone also prevent H2O2 formation. They also exclude ubiquinol, which remains reduced under these conditions, as the reductant of O2. Since cytochrome b also remains fully reduced when myxothiazol is added to succinate- and antimycin A-supplemented mitochondria, reduced cytochrome b may also be excluded as the reductant of O2. These observations, which are consistent with the Q-cycle reactions, by exclusion of other possibilities leave ubisemiquinone as the only reduced electron carrier in complex III capable of reducing O2 to O2-.

  6. Evidence for a hyperglycaemia-dependent decrease of antithrombin III-thrombin complex formation in humans.

    PubMed

    Ceriello, A; Giugliano, D; Quatraro, A; Marchi, E; Barbanti, M; Lefèbvre, P

    1990-03-01

    In the presence of increased levels of fibrinopeptide A, decreased antithrombin III biological activity, and thrombin-antithrombin III complex levels are seen in diabetic patients. Induced-hyperglycaemia in diabetic and normal subjects decreased antithrombin III activity and thrombin-antithrombin III levels, and increased fibrinopeptide A plasma levels, while antithrombin III concentration did not change; heparin was shown to reduced these phenomena. In diabetic patients, euglycaemia induced by insulin infusion restored antithrombin III activity, thrombin-antithrombin III complex and fibrinopeptide A concentrations; heparin administration had the same effects. These data stress the role of a hyperglycaemia-dependent decrease of antithrombin III activity in precipitating thrombin hyperactivity in diabetes mellitus.

  7. Pyridinophane platform for stable lanthanide(III) complexation.

    PubMed

    Castro, Goretti; Bastida, Rufina; Macías, Alejandro; Pérez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, Laura

    2013-05-20

    A detailed investigation of the solid state and solution structures of lanthanide(III) complexes with the macrocyclic ligand 2,11,20-triaza[3.3.3](2,6)pyridinophane (TPP) is reported. The solid state structures of 14 different Ln(3+) complexes have been determined using X-ray crystallography. The ligand is coordinating to the Ln(3+) ion by using its six nitrogen atoms, while nitrate or triflate anions and water molecules complete the metal coordination environments. The structure of the complexes in solution has been investigated by (1)H and (13)C NMR spectroscopy, as well as by DFT calculations (TPSSh model) performed in aqueous solution. The structures obtained from these calculations for the complexes with the lightest Ln(3+) ions (La-Sm) are in very good agreement with those determined by the analysis of the Ln(3+)-induced paramagnetic shifts. A structural change occurs across the lanthanide series at Sm(3+); the complexes of the large Ln(3+) ions (La-Nd) are chiral due to the nonplanar conformation of the macrocycle, and present effective C3v symmetries in solution as a consequence of a fast interconversion of two enantiomeric forms with C3 symmetry. The activation free energy for this enantiomerization process, as estimated by using DFT calculations, amounts to 33.0 kJ·mol(-1). The TPP ligand in the complexes of the heaviest Ln(3+) ions (Eu-Lu) presents a half-chair conformation, which results in C(s) symmetries in solution.

  8. Exceptional Oxygen Sensing Properties of New Blue Light-Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

    PubMed Central

    Borisov, Sergey M.; Fischer, Roland; Saf, Robert; Klimant, Ingo

    2016-01-01

    New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-of-the-art oxygen indicators particularly for such applications as e.g. food packaging. PMID:27158252

  9. Adsorption and mobility of Cr(III)-organic acid complexes in soils.

    PubMed

    Cao, Xinhua; Guo, Jing; Mao, Jingdong; Lan, Yeqing

    2011-09-15

    The soluble Cr(III) is likely to be complexed with organic ligands in ligand-rich soil. Cr(VI) chemical reduction by organic acids and bioreduction by microorganisms can produce soluble Cr(III)-organic acids complexes. Thus, it is of great significance to investigate the absorption and mobility of Cr(III)-organic acid complexes in soils. In this study, Cr(III)-EDTA and Cr(III)-cit were prepared and purified, and then were examined for adsorption and mobility. The results demonstrated that Cr(III) was strongly bound to soil, while Cr(III)-organic acid complexes had no or slight interaction with soils since Cr(III)-EDTA and Cr(III)-cit complexes mainly existed as the forms of [Cr(III)-EDTA](-) and [Cr(III)-cit], respectively, under the tested conditions with initial pH 4.0-9.0. The adsorption of Cr(III) increased but that of Cr(III)-organic acid complexes decreased with the content of soil organic matter. Compared with Cr(III)-EDTA, the mobility of Cr(III)-cit in soil columns was reduced, due to the specific adsorption between soils and Cr(III)-cit which contained one free hydroxyl group. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Preparation of new fluorophore lanthanide complexes-Cloisite nanohybrids using the tricationic Pr(III), Gd(III) and Dy(III) complexes with 9,10-phenanthrenequinone.

    PubMed

    Mallakpour, Shadpour; Behnamfar, Mohammad Taghi; Dinari, Mohammad; Hadadzadeh, Hassan

    2015-02-25

    New fluorophore lanthanide complexes-Cloisite (LCs-C) nanohybrids have been prepared by the intercalation reaction of Cloisite Na(+) with the tricationic lanthanide complexes (1-3), [M(PQ)3(DMF)2(H2O)2](3+) (M=Pr(III) (1), Gd(III) (2), and Dy(III) (3); PQ=9,10-phenanthrenequinone), in aqueous solutions. The X-ray diffraction analysis of the modified clays (LCs-C) showed an increase in the interlayer distance (d) as compared to the pure Cloisite Na(+). Field-emission scanning electron microscopy (FE-SEM) was used to study the morphology of the modified clays and the results were demonstrated a homogeneous morphology for the nanohybrids. The thermal behavior of the LCs-C nanohybrids was investigated using thermogravimetric analysis. Solid-state fluorescence properties of the LCs-C nanohybrids were also investigated. The results show that all tricationic complexes have a significant fluorescence at room temperature when the complexes are adsorbed onto Cloisite.

  11. Synthesis of square-planar aluminum(III) complexes.

    PubMed

    Thompson, Emily J; Myers, Thomas W; Berben, Louise A

    2014-12-15

    The synthesis of two four-coordinate and square planar (SP) complexes of aluminum(III) is presented. Reaction of a phenyl-substituted bis(imino)pyridine ligand that is reduced by two electrons, Na2((Ph)I2P(2-)), with AlCl3 afforded five-coordinate [((Ph)I2P(2-))Al(THF)Cl] (1). Square-planar [((Ph)I2P(2-))AlCl] (2) was obtained by performing the same reaction in diethyl ether followed by lyphilization of 2 from benzene. The four-coordinate geometry index for 2, τ4, is 0.22, where 0 would be a perfectly square-planar molecule. The analogous aluminum hydride complex, [((Ph)I2P(2-))AlH] (3), is also square-planar, and was characterized crystallographically and has τ4=0.13. Both 2 and 3 are Lewis acidic and bind 2,6-lutidine.

  12. Luminescent chiral lanthanide(III) complexes as potential molecular probes

    PubMed Central

    Muller, Gilles

    2009-01-01

    This perspective gives an introduction into the design of luminescent lanthanide(III)-containing complexes possessing chiral properties and used to probe biological materials. The first part briefly describes general principles, focusing on the optical aspect (i.e. lanthanide luminescence, sensitization processes) of the most emissive trivalent lanthanide ions, europium and terbium, incorporated into molecular luminescent edifices. This is followed by a short discussion on the importance of chirality in the biological and pharmaceutical fields. The second part is devoted to the assessment of the chiroptical spectroscopic tools available (typically circular dichroism and circularly polarized luminescence) and the strategies used to introduce a chiral feature into luminescent lanthanide(III) complexes (chiral structure resulting from a chiral arrangement of the ligand molecules surrounding the luminescent center or presence of chiral centers in the ligand molecules). Finally, the last part illustrates these fundamental principles with recent selected examples of such chiral luminescent lanthanide-based compounds used as potential probes of biomolecular substrates. PMID:19885510

  13. Affection of the Respiratory Muscles in Combined Complex I and IV Deficiency

    PubMed Central

    Finsterer, Josef; Rauschka, Helmut; Segal, Liane; Kovacs, Gabor G.; Rolinski, Boris

    2017-01-01

    Objectives: Combined complex I+IV deficiency has rarely been reported to manifest with the involvement of the respiratory muscles. Case Report: A 45y male was admitted for hypercapnia due to muscular respiratory insufficiency. He required intubation and mechanical ventilation. He had a previous history of ophthalmoparesis since age 6y, ptosis since age 23y, and anterocollis since at least age 40y. Muscle biopsy from the right deltoid muscle at age 41y was indicative of mitochondrial myopathy. Biochemical investigations revealed a combined complex I+IV defect. Respiratory insufficiency was attributed to mitochondrial myopathy affecting not only the extra-ocular and the axial muscles but also the shoulder girdle and respiratory muscles. In addition to myopathy, he had mitochondrial neuropathy, abnormal EEG, and elevated CSF-protein. Possibly, this is why a single cycle of immunoglobulins was somehow beneficial. For muscular respiratory insufficiency he required tracheostomy and was scheduled for long-term intermittent positive pressure ventilation. Conclusion: Mitochondrial myopathy due to a combined complex I+IV defect with predominant affection of the extra-ocular muscles may progress to involvement of the limb-girdle, axial and respiratory muscles resulting in muscular respiratory insufficiency. In patients with mitochondrial myopathy, neuropathy and elevated cerebrospinal fluid protein, immunoglobulins may be beneficial even for respiratory functions. PMID:28217183

  14. Identification and functional prediction of mitochondrial complex III and IV mutations associated with glioblastoma

    PubMed Central

    Lloyd, Rhiannon E.; Keatley, Kathleen; Littlewood, D. Timothy J.; Meunier, Brigitte; Holt, William V.; An, Qian; Higgins, Samantha C.; Polyzoidis, Stavros; Stephenson, Katie F.; Ashkan, Keyoumars; Fillmore, Helen L.; Pilkington, Geoffrey J.; McGeehan, John E.

    2015-01-01

    Background Glioblastoma (GBM) is the most common primary brain tumor in adults, with a dismal prognosis. Treatment is hampered by GBM's unique biology, including differential cell response to therapy. Although several mitochondrial abnormalities have been identified, how mitochondrial DNA (mtDNA) mutations contribute to GBM biology and therapeutic response remains poorly described. We sought to determine the spectrum of functional complex III and IV mtDNA mutations in GBM. Methods The complete mitochondrial genomes of 10 GBM cell lines were obtained using next-generation sequencing and combined with another set obtained from 32 GBM tissues. Three-dimensional structural mapping and analysis of all the nonsynonymous mutations identified in complex III and IV proteins was then performed to investigate functional importance. Results Over 200 mutations were identified in the mtDNAs, including a significant proportion with very low mutational loads. Twenty-five were nonsynonymous mutations in complex III and IV, 9 of which were predicted to be functional and affect mitochondrial respiratory chain activity. Most of the functional candidates were GBM specific and not found in the general population, and 2 were present in the germ-line. Patient-specific maps reveal that 43% of tumors carry at least one functional candidate. Conclusions We reveal that the spectrum of GBM-associated mtDNA mutations is wider than previously thought, as well as novel structural-functional links between specific mtDNA mutations, abnormal mitochondria, and the biology of GBM. These results could provide tangible new prognostic indicators as well as targets with which to guide the development of patient-specific mitochondrially mediated chemotherapeutic approaches. PMID:25731774

  15. Sparkle/AM1 Parameters for the Modeling of Samarium(III) and Promethium(III) Complexes.

    PubMed

    Freire, Ricardo O; da Costa, Nivan B; Rocha, Gerd B; Simas, Alfredo M

    2006-01-01

    The Sparkle/AM1 model is extended to samarium(III) and promethium(III) complexes. A set of 15 structures of high crystallographic quality (R factor < 0.05 Å), with ligands chosen to be representative of all samarium complexes in the Cambridge Crystallographic Database 2004, CSD, with nitrogen or oxygen directly bonded to the samarium ion, was used as a training set. In the validation procedure, we used a set of 42 other complexes, also of high crystallographic quality. The results show that this parametrization for the Sm(III) ion is similar in accuracy to the previous parametrizations for Eu(III), Gd(III), and Tb(III). On the other hand, promethium is an artificial radioactive element with no stable isotope. So far, there are no promethium complex crystallographic structures in CSD. To circumvent this, we confirmed our previous result that RHF/STO-3G/ECP, with the MWB effective core potential (ECP), appears to be the most efficient ab initio model chemistry in terms of coordination polyhedron crystallographic geometry predictions from isolated lanthanide complex ion calculations. We thus generated a set of 15 RHF/STO-3G/ECP promethium complex structures with ligands chosen to be representative of complexes available in the CSD for all other trivalent lanthanide cations, with nitrogen or oxygen directly bonded to the lanthanide ion. For the 42 samarium(III) complexes and 15 promethium(III) complexes considered, the Sparkle/AM1 unsigned mean error, for all interatomic distances between the Ln(III) ion and the ligand atoms of the first sphere of coordination, is 0.07 and 0.06 Å, respectively, a level of accuracy comparable to present day ab initio/ECP geometries, while being hundreds of times faster.

  16. Synthesis of supramolecular iron (III) complexes by cluster aggregation

    NASA Astrophysics Data System (ADS)

    Seddon, Elisa Joy

    2000-12-01

    Biologically, iron is a ubiquitous and versatile metal, found in the active sites of proteins responsible for both oxygen and electron transport. Multinuclear iron-oxo proteins are either dinuclear, or contain many iron atoms; the [Fe2O] unit occurs in hemerythrin (Hr), ribonucleotide reductase, purple acid phosphatase (POP) and methane monooxygenase (MMO), whereas ferritin (Ft) can store up to 4500 iron atoms. Iron storage and transport are essential for protecting biological organisms from free iron, since free Fe(II) ions, will react with dioxygen to form destructive organic radicals, and free Fe(III) ions form insoluble iron hydroxide aggregates under physiological conditions. The tendency of iron to form molecular aggregates in systems containing water or alcohol, together with the fact that each iron atom possesses a large number of unpaired electrons (5 for high-spin FeIII) often results in products possessing large spin ground states (S). The current record-holder for iron is a Fe19 complex, with at least 33 unpaired electrons in the ground state (S = 33/2). Hence, iron is also important in the rapidly developing field of molecular magnetic materials. For these two reasons, the preparation of iron clusters with new topologies and properties has become a major goal of many synthetic inorganic groups, including our own. In this thesis work, synthetic and spectroscopic methods of inorganic coordination chemistry were used to achieve two different goals: firstly, to synthesize dinuclear iron complexes with the use of tetradentate ligands in order to study the magnetic interactions between the two metal centers; and secondly, to identify reactions and characterize the products whereby pre-formed iron oxide clusters undergo aggregation reactions to produce higher nuclearity products. The tetradentate ligands investigated were a bis-(beta-diketone) ligand L and a bis-bpy ligand L'. The reactions involving L and Fe(III) reagents produced complexes with a triple

  17. Cerium(III) and neodymium(III) complexes as scavengers of X/XO-derived superoxide radical.

    PubMed

    Kostova, Irena; Traykova, Maria

    2006-09-01

    The cerium (III) and neodymium (III) complexes with 3,3'-benzylidenebis[4-hydroxycoumarin] were synthesized and characterized by different analytical and spectral methods. The synthesis of these complexes is taken into consideration with cytotoxic screening and study of their antioxidant effect. Their cytotoxicity toward cancerous cell cultures correlated with the weakness of the coordinative bond between the cation and organic ligand and with the capability to scavenge superoxide radicals as well. On the basis of the data reported by us earlier and our new results, it was proposed that cerium (III) complex with 3,3'-benzylidenebis[4-hydroxycoumarin] might induce intracellular acidification along with control over the extracellular oxidative stress.

  18. Diet and Respiratory Health in Children from 11 Latin American Countries: Evidence from ISAAC Phase III.

    PubMed

    Cepeda, Alfonso Mario; Thawer, Sumaiyya; Boyle, Robert J; Villalba, Sara; Jaller, Rodolfo; Tapias, Elmy; Segura, Ana María; Villegas, Rodrigo; Garcia-Larsen, Vanessa

    2017-08-28

    The burden of childhood asthma and its risk factors is an important but neglected public health challenge in Latin America. We investigated the association between allergic symptoms and dietary intake in children from this region. As part of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase III, questionnaire collected dietary intake was investigated in relation to risk of parental/child reported current wheeze (primary outcome) and rhino-conjunctivitis and eczema. Per-country adjusted logistic regressions were performed, and combined effect sizes were calculated with meta-analyses. 143,967 children from 11 countries had complete data. In children aged 6-7 years, current wheeze was negatively associated with higher fruit intake (adjusted odds ratio [aOR] 0.65; 95% CI 0.74, 0.97). Current rhino-conjunctivitis and eczema were statistically negatively associated with fruit intake (aOR 0.72; 95% CI 0.64, 0.82; and OR 0.64, 95% CI 0.56, 0.74, respectively). Vegetable intake was negatively associated with risk of symptoms in younger children, but these associations were attenuated in the 13-14 years old group. Fastfood/burger intake was positively associated with all three outcomes in the older children. A higher intake of fruits and vegetables was associated with a lower prevalence of allergic symptoms in Latin American children. Conversely, intake of fastfood was positively associated with a higher prevalence of wheeze in adolescents. Improved dietary habits in children might help reduce the epidemic of allergic symptoms in Latin America. Food interventions in asthmatic children are needed to evaluate the possible public health impact of a better diet on respiratory health.

  19. Dihydro-orotate dehydrogenase is physically associated with the respiratory complex and its loss leads to mitochondrial dysfunction

    PubMed Central

    Fang, JingXian; Uchiumi, Takeshi; Yagi, Mikako; Matsumoto, Shinya; Amamoto, Rie; Takazaki, Shinya; Yamaza, Haruyoshi; Nonaka, Kazuaki; Kang, Dongchon

    2012-01-01

    Some mutations of the DHODH (dihydro-orotate dehydrogenase) gene lead to postaxial acrofacial dysostosis or Miller syndrome. Only DHODH is localized at mitochondria among enzymes of the de novo pyrimidine biosynthesis pathway. Since the pyrimidine biosynthesis pathway is coupled to the mitochondrial RC (respiratory chain) via DHODH, impairment of DHODH should affect the RC function. To investigate this, we used siRNA (small interfering RNA)-mediated knockdown and observed that DHODH knockdown induced cell growth retardation because of G2/M cell-cycle arrest, whereas pyrimidine deficiency usually causes G1/S arrest. Inconsistent with this, the cell retardation was not rescued by exogenous uridine, which should bypass the DHODH reaction for pyrimidine synthesis. DHODH depletion partially inhibited the RC complex III, decreased the mitochondrial membrane potential, and increased the generation of ROS (reactive oxygen species). We observed that DHODH physically interacts with respiratory complexes II and III by IP (immunoprecipitation) and BN (blue native)/SDS/PAGE analysis. Considering that pyrimidine deficiency alone does not induce craniofacial dysmorphism, the DHODH mutations may contribute to the Miller syndrome in part through somehow altered mitochondrial function. PMID:23216091

  20. Differential effects of buffer pH on Ca2+-induced ROS emission with inhibited mitochondrial complexes I and III

    PubMed Central

    Lindsay, Daniel P.; Camara, Amadou K. S.; Stowe, David F.; Lubbe, Ryan; Aldakkak, Mohammed

    2015-01-01

    Excessive mitochondrial reactive oxygen species (ROS) emission is a critical component in the etiology of ischemic injury. Complex I and complex III of the electron transport chain are considered the primary sources of ROS emission during cardiac ischemia and reperfusion (IR) injury. Several factors modulate ischemic ROS emission, such as an increase in extra-matrix Ca2+, a decrease in extra-matrix pH, and a change in substrate utilization. Here we examined the combined effects of these factors on ROS emission from respiratory complexes I and III under conditions of simulated IR injury. Guinea pig heart mitochondria were suspended in experimental buffer at a given pH and incubated with or without CaCl2. Mitochondria were then treated with either pyruvate, a complex I substrate, followed by rotenone, a complex I inhibitor, or succinate, a complex II substrate, followed by antimycin A, a complex III inhibitor. H2O2 release rate and matrix volume were compared with and without adding CaCl2 and at pH 7.15, 6.9, or 6.5 with pyruvate + rotenone or succinate + antimycin A to simulate conditions that may occur during in vivo cardiac IR injury. We found a large increase in H2O2 release with high [CaCl2] and pyruvate + rotenone at pH 6.9, but not at pHs 7.15 or 6.5. Large increases in H2O2 release rate also occurred at each pH with high [CaCl2] and succinate + antimycin A, with the highest levels observed at pH 7.15. The increases in H2O2 release were associated with significant mitochondrial swelling, and both H2O2 release and swelling were abolished by cyclosporine A, a desensitizer of the mitochondrial permeability transition pore (mPTP). These results indicate that ROS production by complex I and by complex III is differently affected by buffer pH and Ca2+ loading with mPTP opening. The study suggests that changes in the levels of cytosolic Ca2+ and pH during IR alter the relative amounts of ROS produced at mitochondrial respiratory complex I and complex III. PMID

  1. Six-coordinate lanthanide complexes: slow relaxation of magnetization in the dysprosium(III) complex.

    PubMed

    Na, Bo; Zhang, Xue-Jing; Shi, Wei; Zhang, Yi-Quan; Wang, Bing-Wu; Gao, Chen; Gao, Song; Cheng, Peng

    2014-11-24

    A series of six-coordinate lanthanide complexes {(H3O)[Ln(NA)2]⋅H2O}n (H2NA=5-hydroxynicotinic acid; Ln=Gd(III) (1⋅Gd); Tb(III) (2⋅Tb); Dy(III) (3⋅Dy); Ho(III) (4⋅Ho)) have been synthesized from aqueous solution and fully characterized. Slow relaxation of the magnetization was observed in 3⋅Dy. To suppress the quantum tunneling of the magnetization, 3⋅Dy diluted by diamagnetic Y(III) ions was also synthesized and magnetically studied. Interesting butterfly-like hysteresis loops and an enhanced energy barrier for the slow relaxation of magnetization were observed in diluted 3⋅Dy. The energy barrier (Δ(τ)) and pre-exponential factor (τ0) of the diluted 3⋅Dy are 75 K and 4.21×10(-5) s, respectively. This work illustrates a successful way to obtain low-coordination-number lanthanide complexes by a framework approach to show single-ion-magnet-like behavior.

  2. Complexity measures of the central respiratory networks during wakefulness and sleep

    NASA Astrophysics Data System (ADS)

    Dragomir, Andrei; Akay, Yasemin; Curran, Aidan K.; Akay, Metin

    2008-06-01

    Since sleep is known to influence respiratory activity we studied whether the sleep state would affect the complexity value of the respiratory network output. Specifically, we tested the hypothesis that the complexity values of the diaphragm EMG (EMGdia) activity would be lower during REM compared to NREM. Furthermore, since REM is primarily generated by a homogeneous population of neurons in the medulla, the possibility that REM-related respiratory output would be less complex than that of the awake state was also considered. Additionally, in order to examine the influence of neuron vulnerabilities within the rostral ventral medulla (RVM) on the complexity of the respiratory network output, we inhibited respiratory neurons in the RVM by microdialysis of GABAA receptor agonist muscimol. Diaphragm EMG, nuchal EMG, EEG, EOG as well as other physiological signals (tracheal pressure, blood pressure and respiratory volume) were recorded from five unanesthetized chronically instrumented intact piglets (3-10 days old). Complexity of the diaphragm EMG (EMGdia) signal during wakefulness, NREM and REM was evaluated using the approximate entropy method (ApEn). ApEn values of the EMGdia during NREM and REM sleep were found significantly (p < 0.05 and p < 0.001, respectively) lower than those of awake EMGdia after muscimol inhibition. In the absence of muscimol, only the differences between REM and wakefulness ApEn values were found to be significantly different.

  3. Mono- and bis-tolylterpyridine iridium(III) complexes

    SciTech Connect

    Hinkle, Lindsay M.; Young, Jr., Victor G.; Mann, Kent R.

    2012-01-20

    The first structure report of trichlorido[4'-(p-tolyl)-2,2':6',2{double_prime}-terpyridine]iridium(III) dimethyl sulfoxide solvate, [IrCl{sub 3}(C{sub 22}H{sub 17}N{sub 3})] {center_dot} C{sub 2}H{sub 6}OS, (I), is presented, along with a higher-symmetry setting of previously reported bis[4'-(p-tolyl)-2,2':6',2{double_prime}-terpyridine]iridium(III) tris(hexafluoridophosphate) acetonitrile disolvate, [Ir(C{sub 22}H{sub 17}N{sub 3})2](PF{sub 6}){sub 3} {center_dot} 2C{sub 2}H{sub 3}N, (II) [Yoshikawa, Yamabe, Kanehisa, Kai, Takashima & Tsukahara (2007). Eur. J. Inorg. Chem. pp. 1911-1919]. For (I), the data were collected with synchrotron radiation and the dimethyl sulfoxide solvent molecule is disordered over three positions, one of which is an inversion center. The previously reported structure of (II) is presented in the more appropriate C2/c space group. The iridium complex and one PF{sub 6}{sup -} anion lie on twofold axes in this structure, making half of the molecule unique.

  4. The Silver Complexes of Porphyrins, Corroles, and Carbaporphyrins: Silver in the Oxidation States II and III

    ERIC Educational Resources Information Center

    Bruckner, Christian

    2004-01-01

    Studies in relation to the silver complexes of porphyrins, corroles and carbaporphyrins are presented especially with relation to silver in the oxidation states II and III. It is seen that the Ag(sub III) complex was electrochemically readily and reversibly reduced to the corresponding Ag(sub II) complex, thus indicating that the complex could be…

  5. The Silver Complexes of Porphyrins, Corroles, and Carbaporphyrins: Silver in the Oxidation States II and III

    ERIC Educational Resources Information Center

    Bruckner, Christian

    2004-01-01

    Studies in relation to the silver complexes of porphyrins, corroles and carbaporphyrins are presented especially with relation to silver in the oxidation states II and III. It is seen that the Ag(sub III) complex was electrochemically readily and reversibly reduced to the corresponding Ag(sub II) complex, thus indicating that the complex could be…

  6. Analysis of gold(I/III)-complexes by HPLC-ICP-MS demonstrates gold(III) stability in surface waters.

    PubMed

    Ta, Christine; Reith, Frank; Brugger, Joël; Pring, Allan; Lenehan, Claire E

    2014-05-20

    Understanding the form in which gold is transported in surface- and groundwaters underpins our understanding of gold dispersion and (bio)geochemical cycling. Yet, to date, there are no direct techniques capable of identifying the oxidation state and complexation of gold in natural waters. We present a reversed phase ion-pairing HPLC-ICP-MS method for the separation and determination of aqueous gold(III)-chloro-hydroxyl, gold(III)-bromo-hydroxyl, gold(I)-thiosulfate, and gold(I)-cyanide complexes. Detection limits for the gold species range from 0.05 to 0.30 μg L(-1). The [Au(CN)2](-) gold cyanide complex was detected in five of six waters from tailings and adjacent monitoring bores of working gold mines. Contrary to thermodynamic predictions, evidence was obtained for the existence of Au(III)-complexes in circumneutral, hypersaline waters of a natural lake overlying a gold deposit in Western Australia. This first direct evidence for the existence and stability of Au(III)-complexes in natural surface waters suggests that Au(III)-complexes may be important for the transport and biogeochemical cycling of gold in surface environments. Overall, these results show that near-μg L(-1) enrichments of Au in environmental waters result from metastable ligands (e.g., CN(-)) as well as kinetically controlled redox processes leading to the stability of highly soluble Au(III)-complexes.

  7. Anionic carbonato and oxalato cobalt(III) nitrogen mustard complexes.

    PubMed

    Craig, Peter R; Brothers, Penelope J; Clark, George R; Wilson, William R; Denny, William A; Ware, David C

    2004-02-21

    Synthetic approaches to cobalt(III) complexes [Co(L)(L')2] containing the bidentate dialkylating nitrogen mustard N,N-bis(2-chloroethyl)-1,2-ethanediamine (L = dce) together with anionic ancilliary ligands (L') which are either carbonato (CO3(2-)), oxalato (ox2-), bis(2-hydroxyethyl)dithiocarbamato (bhedtc-), 2-pyridine carboxylato (pico-) or 2-pyrazine carboxylato (pyzc-) were investigated. Synthetic routes were developed using the related amines N,N-diethyl-1,2-ethanediamine (dee) and 1,2-ethanediamine (en). The complexes [Co(CO3)2(L)]- (L = dee 1, dce 2), [Co(ox)2(L)]- (L = dee 3, dce 4), [Co(bhedtc)2(dee)]+ 5, [Co(bhedtc)2(en)]+ 6, mer-[Co(pico)3], mer-[Co(pyzc)]3 7 and [Co(pico)2(dee)]+ 8 were prepared and were characterised by IR, UV-Vis, 1H and 13C[1H] NMR spectroscopy, mass spectrometry and cyclic voltammetry. [Co(bhedtc)2(en)]BPh4 6b and trans(O)-[Co(pico)2(dee)]ClO4 8 were characterised by X-ray crystallography. In vitro biological tests were carried out on complexes 1-4 in order to assess the degree to which coordination of the mustard to cobalt attenuated its cytotoxicity, and the differential toxicity in air vs. nitrogen.

  8. Chemical and biological reduction of Mn (III)-pyrophosphate complexes: Potential importance of dissolved Mn (III) as an environmental oxidant

    NASA Astrophysics Data System (ADS)

    Kostka, Joel E.; Luther, George W., III; Nealson, Kenneth H.

    1995-03-01

    Dissolved Mn (III) is a strong oxidant which could play an important role in the biogeochemistry of aquatic environments, but little is known about this form of Mn. Mn(III) was shown to form a stable complex with pyrophosphate which is easily measured by uv-vis spectrophotometry. The Mn(III)-pyrophosphate complex was produced at concentrations of 5 μM to 10 mM Mn at neutral pH. Inorganic electron donors, Fe(II) and sulfide, abiotically reduced Mn(III)-pyrophosphate in seconds with a stoichiometry of 1:1 and near 1:2 reductant:Mn (III), respectively. Shewanella putrefaciens strain MR-1 catalyzed the reduction of Mn(III)-pyrophosphate with formate or lactate as electron donors. Reduction of Mn(III) catalyzed by MR-1 was inhibited under aerobic conditions but only slightly under anaerobic conditions upon addition of the alternate electron acceptor, nitrate. MR-1 catalyzed reduction was also inhibited by metabolic inhibitors including formaldehyde, tetrachlorosalicylanilide (TCS), carbonyl cyanide m-chlorophenylhydrazone (CCCP), 2- n-heptyl-4-hydroxyquinoline N-oxide (HQNO), but not antimycin A. When formate or lactate served as electron donor for Mn(III) reduction, carbon oxidation to CO 2 was coupled to the respiration of Mn (III). Using the incorporation of 3H-leucine into the TCA-insoluble fraction of culture extracts, it was shown that Mn (III) reduction was coupled to protein synthesis in MR-1. These data indicate that Mn (III) complexes may be produced under conditions found in aquatic environments and that the reduction of Mn(III) can be coupled to the cycling of Fe, S, and C.

  9. Building a complex complex: Assembly of mitochondrial respiratory chain complex I.

    PubMed

    Formosa, Luke E; Dibley, Marris G; Stroud, David A; Ryan, Michael T

    2017-08-07

    Mitochondrial complex I is the primary entry point for electrons into the electron transport chain, required for the bulk of cellular ATP production via oxidative phosphorylation. Complex I consists of 45 subunits, which are encoded by both nuclear and mitochondrial DNA. Currently, at least 15 assembly factors are known to be required for the complete maturation of complex I. Mutations in the genes encoding subunits and assembly factors lead to complex I deficiency, which can manifest as mitochondrial disease. The current model of complex I assembly suggests that the enzyme is built by the association of a set of smaller intermediate modules containing specific conserved core subunits and additional accessory subunits. Each module must converge in a spatially and temporally orchestrated fashion to allow assembly of the mature holoenzyme to occur. This review outlines the current understanding of complex I biogenesis, with an emphasis on the assembly factors that facilitate the building of this architectural giant. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Schizosaccharomyces pombe homologs of the Saccharomyces cerevisiae mitochondrial proteins Cbp6 and Mss51 function at a post-translational step of respiratory complex biogenesis

    PubMed Central

    Kühl, Inge; Fox, Thomas D.; Bonnefoy, Nathalie

    2012-01-01

    Complexes III and IV of the mitochondrial respiratory chain contain a few key subunits encoded by the mitochondrial genome. In Saccharomyces cerevisiae, fifteen mRNA-specific translational activators control mitochondrial translation, of which five are conserved in Schizosaccharomyces pombe. These include homologs of Cbp3, Cbp6 and Mss51 that participate in translation and the post-translational steps leading to the assembly of respiratory complexes III and IV. In this study we show that in contrast to budding yeast, Cbp3, Cbp6 and Mss51 from S. pombe are not required for the translation of mitochondrial mRNAs, but fulfill post-translational functions, thus probably accounting for their conservation. PMID:22349564

  11. Oxidation of cuprous stellacyanin by aminopolycarboxylatocobaltate(III) complexes.

    PubMed

    Yoneda, G S; Mitchel, G L; Blackmer, G L; Holwerda, R A

    1978-01-01

    Rate parameters are reported for the oxidation of cuprous stellacyanin by Co(PDTA)-(k(25.0 degrees) = 17.9 M(-1)sec(-1), deltaH not equal to = 8.5 kcal/mol, deltaH not equal to = 8.5 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0, Mu 0.5 M) and Co(CyDTA)-(k(25.1 degrees) = 17.0 M(-1)sec(-1), deltaH not equal to = 8.7 kcal/mol, deltaS not equal to = -24 cal/mol-deg; pH 7.0 mu 0.5 M). The first order Co(PDTA)- and Co(CyDTA)- dependences observed over wide concentration ranges contrast with the saturation behavior reported previously for Co(EDTA)- as the oxidant. It is concluded that the- CH3 and -(CH2)4-substituents of PDTA and CyDTA, respectively, prevent the alkylated derivatives of Co(EDTA)- from hydrogen bonding with the reduced blue protein, causing precursor complex formation constants to fall far below that of 149M(-1) (25.1 degrees) observed for the EDTA complex. The similarity between deltaH not equal to and deltaS not equal to values for the oxidation of stellacyanin by Co(PDTA)- and Co(CyDTA)- indicates that the size of alkyl substituents linked to the carbon atoms of the EDTA ethylenediamine backbone has little influence on activation requirements for Cu(I) to Co(III) electron transfer. The electron transfer reactivity of aminopolycarboxylatocobalt(III) complexes with cuprous stellacyanin therefore appears to be linked to the accessibility of one or more of the ligated acetate groups to outer-sphere contact with the type 1 Cu(I) center. Saturation in kobsd vs. [oxidant] plots found for the reactions of Co(PDTA)- and Co(CyDTA)- with stellacyanin at pH 6 and at pH 7 in the presence of EDTA is attributed to the formation of "dead-end" oxidant-protein complexes.

  12. Formation of Gold(III) Alkyls from Gold Alkoxide Complexes

    PubMed Central

    2017-01-01

    The gold(III) methoxide complex (C∧N∧C)AuOMe (1) reacts with tris(p-tolyl)phosphine in benzene at room temperature under O abstraction to give the methylgold product (C∧N∧C)AuMe (2) together with O=P(p-tol)3 ((C∧N∧C) = [2,6-(C6H3tBu-4)2pyridine]2–). Calculations show that this reaction is energetically favorable (ΔG = −32.3 kcal mol–1). The side products in this reaction, the Au(II) complex [Au(C∧N∧C)]2 (3) and the phosphorane (p-tol)3P(OMe)2, suggest that at least two reaction pathways may operate, including one involving (C∧N∧C)Au• radicals. Attempts to model the reaction by DFT methods showed that PPh3 can approach 1 to give a near-linear Au–O–P arrangement, without phosphine coordination to gold. The analogous reaction of (C∧N∧C)AuOEt, on the other hand, gives exclusively a mixture of 3 and (p-tol)3P(OEt)2. Whereas the reaction of (C∧N∧C)AuOR (R = But, p-C6H4F) with P(p-tol)3 proceeds over a period of hours, compounds with R = CH2CF3, CH(CF3)2 react almost instantaneously, to give 3 and O=P(p-tol)3. In chlorinated solvents, treatment of the alkoxides (C∧N∧C)AuOR with phosphines generates [(C∧N∧C)Au(PR3)]Cl, via Cl abstraction from the solvent. Attempts to extend the synthesis of gold(III) alkoxides to allyl alcohols were unsuccessful; the reaction of (C∧N∧C)AuOH with an excess of CH2=CHCH2OH in toluene led instead to allyl alcohol isomerization to give a mixture of gold alkyls, (C∧N∧C)AuR′ (R′ = −CH2CH2CHO (10), −CH2CH(CH2OH)OCH2CH=CH2 (11)), while 2-methallyl alcohol affords R′ = CH2CH(Me)CHO (12). The crystal structure of 11 was determined. The formation of Au–C instead of the expected Au–O products is in line with the trend in metal–ligand bond dissociation energies for Au(III): M–H > M–C > M–O.

  13. Respiratory Complex I in Bos taurus and Paracoccus denitrificans Pumps Four Protons across the Membrane for Every NADH Oxidized.

    PubMed

    Jones, Andrew J Y; Blaza, James N; Varghese, Febin; Hirst, Judy

    2017-03-24

    Respiratory complex I couples electron transfer between NADH and ubiquinone to proton translocation across an energy-transducing membrane to support the proton-motive force that drives ATP synthesis. The proton-pumping stoichiometry of complex I (i.e. the number of protons pumped for each two electrons transferred) underpins all mechanistic proposals. However, it remains controversial and has not been determined for any of the bacterial enzymes that are exploited as model systems for the mammalian enzyme. Here, we describe a simple method for determining the proton-pumping stoichiometry of complex I in inverted membrane vesicles under steady-state ADP-phosphorylating conditions. Our method exploits the rate of ATP synthesis, driven by oxidation of NADH or succinate with different sections of the respiratory chain engaged in catalysis as a proxy for the rate of proton translocation and determines the stoichiometry of complex I by reference to the known stoichiometries of complexes III and IV. Using vesicles prepared from mammalian mitochondria (from Bos taurus) and from the bacterium Paracoccus denitrificans, we show that four protons are pumped for every two electrons transferred in both cases. By confirming the four-proton stoichiometry for mammalian complex I and, for the first time, demonstrating the same value for a bacterial complex, we establish the utility of P. denitrificans complex I as a model system for the mammalian enzyme. P. denitrificans is the first system described in which mutagenesis in any complex I core subunit may be combined with quantitative proton-pumping measurements for mechanistic studies.

  14. Respiratory Complex I in Bos taurus and Paracoccus denitrificans Pumps Four Protons across the Membrane for Every NADH Oxidized*

    PubMed Central

    Jones, Andrew J. Y.; Blaza, James N.; Varghese, Febin; Hirst, Judy

    2017-01-01

    Respiratory complex I couples electron transfer between NADH and ubiquinone to proton translocation across an energy-transducing membrane to support the proton-motive force that drives ATP synthesis. The proton-pumping stoichiometry of complex I (i.e. the number of protons pumped for each two electrons transferred) underpins all mechanistic proposals. However, it remains controversial and has not been determined for any of the bacterial enzymes that are exploited as model systems for the mammalian enzyme. Here, we describe a simple method for determining the proton-pumping stoichiometry of complex I in inverted membrane vesicles under steady-state ADP-phosphorylating conditions. Our method exploits the rate of ATP synthesis, driven by oxidation of NADH or succinate with different sections of the respiratory chain engaged in catalysis as a proxy for the rate of proton translocation and determines the stoichiometry of complex I by reference to the known stoichiometries of complexes III and IV. Using vesicles prepared from mammalian mitochondria (from Bos taurus) and from the bacterium Paracoccus denitrificans, we show that four protons are pumped for every two electrons transferred in both cases. By confirming the four-proton stoichiometry for mammalian complex I and, for the first time, demonstrating the same value for a bacterial complex, we establish the utility of P. denitrificans complex I as a model system for the mammalian enzyme. P. denitrificans is the first system described in which mutagenesis in any complex I core subunit may be combined with quantitative proton-pumping measurements for mechanistic studies. PMID:28174301

  15. New Insights into the Respiratory Chain of Plant Mitochondria. Supercomplexes and a Unique Composition of Complex II1

    PubMed Central

    Eubel, Holger; Jänsch, Lothar; Braun, Hans-Peter

    2003-01-01

    A project to systematically investigate respiratory supercomplexes in plant mitochondria was initiated. Mitochondrial fractions from Arabidopsis, potato (Solanum tuberosum), bean (Phaseolus vulgaris), and barley (Hordeum vulgare) were carefully treated with various concentrations of the nonionic detergents dodecylmaltoside, Triton X-100, or digitonin, and proteins were subsequently separated by (a) Blue-native polyacrylamide gel electrophoresis (PAGE), (b) two-dimensional Blue-native/sodium dodecyl sulfate-PAGE, and (c) two-dimensional Blue-native/Blue-native PAGE. Three high molecular mass complexes of 1,100, 1,500, and 3,000 kD are visible on one-dimensional Blue native gels, which were identified by separations on second gel dimensions and protein analyses by mass spectrometry. The 1,100-kD complex represents dimeric ATP synthase and is only stable under very low concentrations of detergents. In contrast, the 1,500-kD complex is stable at medium and even high concentrations of detergents and includes the complexes I and III2. Depending on the investigated organism, 50% to 90% of complex I forms part of this supercomplex if solubilized with digitonin. The 3,000-kD complex, which also includes the complexes I and III, is of low abundance and most likely has a III4I2 structure. The complexes IV, II, and the alternative oxidase were not part of supercomplexes under all conditions applied. Digitonin proved to be the ideal detergent for supercomplex stabilization and also allows optimal visualization of the complexes II and IV on Blue-native gels. Complex II unexpectedly was found to be composed of seven subunits, and complex IV is present in two different forms on the Blue-native gels, the larger of which comprises additional subunits including a 32-kD protein resembling COX VIb from other organisms. We speculate that supercomplex formation between the complexes I and III limits access of alternative oxidase to its substrate ubiquinol and possibly regulates

  16. A hexadentate bis(thiosemicarbazonato) ligand: rhenium(V), iron(III) and cobalt(III) complexes.

    PubMed

    Paterson, Brett M; White, Jonathan M; Donnelly, Paul S

    2010-03-21

    A new 1,3-diaminopropane bridged bis(thiosemicarbazone) ligand (H(4)L) has been synthesised. The new hexadentate ligand is capable of forming six coordinate complexes with rhenium(V), iron(III) and cobalt(III). In the case of the iron(III) and cobalt(III) complexes the ligand doubly deprotonates to give the monocations [Fe(III)(H(2)L)](+) and [Co(III)(H(2)L)](+) in which the metal ion is in a distorted octahedral environment. In the rhenium(V) complex the ligand loses four protons by deprotonation of both secondary amine nitrogen atoms to give [Re(V)(L)](+) with the metal ion in a distorted trigonal prismatic coordination environment. [Re(V)(L)](+) represents a rare example of a rhenium(V) complex that does not contain one of the ReO(3+), ReN(2+) or Re(NPh)(2+) cores. The new ligand and metal complexes have been characterised by a combination of NMR spectroscopy, X-ray crystallography, mass spectrometry and microanalysis. The electrochemistry of [Fe(III)(H(2)L)](+), [Co(III)(H(2)L)](+) and [Re(V)(L)](+) has been investigated by cyclic voltammetry with each complex undergoing a single electron reduction event. It is possible to prepare the rhenium(V) complex from ReOCl(3)(PPh(3))(2) or directly from [ReO(4)](-) with the addition of a reductant, which suggests the new ligand may be of interest in the development of rhenium radiopharmaceuticals.

  17. Mitochondrial respiratory chain complex IV deficiency complicated with chronic intestinal pseudo-obstruction in a neonate.

    PubMed

    Hashimura, Yuya; Morioka, Ichiro; Hisamatsu, Chieko; Yokoyama, Naoki; Taniguchi-Ikeda, Mariko; Yokozaki, Hiroshi; Murayama, Kei; Ohtake, Akira; Itoh, Kyoko; Takeshima, Yasuhiro; Iijima, Kazumoto

    2016-07-01

    A female infant born at 36 weeks gestational age with birthweight 2135 g, and who developed respiratory disorder, hyperlactacidemia and hypertrophic cardiomyopathy after birth, was admitted to hospital at 3 days of age. After admission, bilious emesis, abdominal distention, and passage disorder of the gastrointestinal tract were resistant to various drugs. Exploratory laparotomy was performed at 93 days of age, but no organic lesions were identified and normal Meissner/Auerbach nerve plexus was confirmed, which led to a clinical diagnosis of chronic intestinal pseudo-obstruction (CIPO). She was diagnosed with mitochondrial respiratory chain complex IV deficiency on histopathology of the abdominal rectus muscle and enzyme activity measurement. This is the first report of a neonate with mitochondrial respiratory chain complex deficiency with intractable CIPO. CIPO can occur in neonates with mitochondrial respiratory chain disorder, necessitating differential diagnosis from Hirschsprung disease.

  18. Lipids of Sarcina lutea III. Composition of the Complex Lipids

    PubMed Central

    Huston, Charles K.; Albro, Phillip W.; Grindey, Gerald B.

    1965-01-01

    Huston, Charles K. (Fort Detrick, Frederick, Md.), Phillip W. Albro, and Gerald B. Grindey. Lipids of Sarcina lutea. III. Composition of the complex lipids. J. Bacteriol. 89:768–775. 1965.—The complex lipids from a strain of Sarcina lutea were isolated and separated into fractions on diethylaminoethyl cellulose acetate and silicic acid columns. These fractions were monitored in several thin-layer chromatography systems. The various lipid types were characterized by their behavior in thin-layer systems and by an analysis of their hydrolysis products. The fatty acid composition of the column fractions was determined by gas-liquid chromatography. A number of components (13) were separated by thin-layer chromatography and characterized. The major components were polyglycerol phosphatide (17.0%), lipoamino acids (15.1%), phosphatidyl glycerol (13.8%), and an incompletely characterized substance (15.0%). Minor constituents included phosphatidyl inositol (5.5%), phosphatidic acid (4.2%), phosphatidyl serine (2.0%), and phosphatidyl choline (1.0%). No phosphatidyl ethanolamine was observed. PMID:14273659

  19. Optimizing millisecond time scale near-infrared emission in polynuclear chrome(III)-lanthanide(III) complexes.

    PubMed

    Aboshyan-Sorgho, Lilit; Nozary, Homayoun; Aebischer, Annina; Bünzli, Jean-Claude G; Morgantini, Pierre-Yves; Kittilstved, Kevin R; Hauser, Andreas; Eliseeva, Svetlana V; Petoud, Stéphane; Piguet, Claude

    2012-08-01

    This work illustrates a simple approach for optimizing long-lived near-infrared lanthanide-centered luminescence using trivalent chromium chromophores as sensitizers. Reactions of the segmental ligand L2 with stoichiometric amounts of M(CF(3)SO(3))(2) (M = Cr, Zn) and Ln(CF(3)SO(3))(3) (Ln = Nd, Er, Yb) under aerobic conditions quantitatively yield the D(3)-symmetrical trinuclear [MLnM(L2)(3)](CF(3)SO(3))(n) complexes (M = Zn, n = 7; M = Cr, n = 9), in which the central lanthanide activator is sandwiched between the two transition metal cations. Visible or NIR irradiation of the peripheral Cr(III) chromophores in [CrLnCr(L2)(3)](9+) induces rate-limiting intramolecular intermetallic Cr→Ln energy transfer processes (Ln = Nd, Er, Yb), which eventually produces lanthanide-centered near-infrared (NIR) or IR emission with apparent lifetimes within the millisecond range. As compared to the parent dinuclear complexes [CrLn(L1)(3)](6+), the connection of a second strong-field [CrN(6)] sensitizer in [CrLnCr(L2)(3)](9+) significantly enhances the emission intensity without perturbing the kinetic regime. This work opens novel exciting photophysical perspectives via the buildup of non-negligible population densities for the long-lived doubly excited state [Cr*LnCr*(L2)(3)](9+) under reasonable pumping powers.

  20. Synthesis and spectroscopic studies of biologically active compounds derived from oxalyldihydrazide and benzil, and their Cr(III), Fe(III) and Mn(III) complexes.

    PubMed

    Singh, D P; Kumar, Ramesh; Singh, Jitender

    2009-04-01

    A new series of complexes have been synthesized by template condensation of oxalyldihydrazide and benzil in methanolic medium in the presence of trivalent chromium, manganese and iron salts forming complexes of the type [M(C(32)H(24)N(8)O(4))X]X(2) where M = Cr(III), Mn(III), Fe(III) and X = Cl(-1), NO(3)(-1), CH(3)COO(-1). The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, NMR, infrared and far infrared spectral studies. On the basis of these studies, a five coordinate square pyramidal geometry has been proposed for all these complexes. The biological activities of the metal complexes have been tested in vitro against a number of pathogenic bacteria to assess their inhibiting potential. Some of these complexes have been found to exhibit remarkable antibacterial activities.

  1. Complexation of Nd(III) with tetraborate ion and its effect on actinide (III) solubility in WIPP brine

    SciTech Connect

    Borkowski, Marian; Richmann, Michael K; Reed, Donald T; Yongliang, Xiong

    2010-01-01

    The potential importance of tetraborate complexation on lanthanide(III) and actinide(III) solubility is recognized in the literature but a systematic study of f-element complexation has not been performed. In neodymium solubility studies in WIPP brines, the carbonate complexation effect is not observed since tetraborate ions form a moderately strong complex with neodymium(III). The existence of these tetraborate complexes was established for low and high ionic strength solutions. Changes in neodymium(III) concentrations in undersaturation experiments were used to determine the neodymium with tetraborate stability constants as a function of NaCl ionic strength. As very low Nd(III) concentrations have to be measured, it was necessary to use an extraction pre-concentration step combined with ICP-MS analysis to extend the detection limit by a factor of 50. The determined Nd(III) with borate stability constants at infinite dilution and 25 C are equal to log {beta}{sub 1} = 4.55 {+-} 0.06 using the SIT approach, equal to log {beta}{sub 1} = 4.99 {+-} 0.30 using the Pitzer approach, with an apparent log {beta}{sub 1} = 4.06 {+-} 0.15 (in molal units) at I = 5.6 m NaCl. Pitzer ion-interaction parameters for neodymium with tetraborate and SIT interaction coefficients were also determined and reported.

  2. Redox-Coupled Protonation of Respiratory Complex I: The Hydrophilic Domain

    PubMed Central

    Couch, Vernon; Popovic, Dragan; Stuchebrukhov, Alexei

    2011-01-01

    Respiratory complex I, NADH:ubiquinone oxidoreductase, is a large and complex integral membrane enzyme found in respiring bacteria and mitochondria. It is responsible in part for generating the proton gradient necessary for ATP production. Complex I serves as both a proton pump and an entry point for electrons into the respiratory chain. Although complex I is one of the most important of the respiratory complexes, it is also one of the least understood, with detailed structural information only recently available. In this study, full-finite-difference Poisson-Boltzmann calculations of the protonation state of respiratory complex I in various redox states are presented. Since complex I couples the oxidation and reduction of the NADH/ubiquinone redox couple to proton translocation, the interaction of the protonation and redox states of the enzyme are of the utmost significance. Various aspects of complex I function are presented, including the redox-Bohr effect, intercofactor interactions, and the effects of both the protein dielectric and inclusion of the membrane. PMID:21767496

  3. The Ins and Outs of Breath Holding: Simple Demonstrations of Complex Respiratory Physiology

    ERIC Educational Resources Information Center

    Skow, Rachel J.; Day, Trevor A.; Fuller, Jonathan E.; Bruce, Christina D.; Steinback, Craig D.

    2015-01-01

    The physiology of breath holding is complex, and voluntary breath-hold duration is affected by many factors, including practice, psychology, respiratory chemoreflexes, and lung stretch. In this activity, we outline a number of simple laboratory activities or classroom demonstrations that illustrate the complexity of the integrative physiology…

  4. The Ins and Outs of Breath Holding: Simple Demonstrations of Complex Respiratory Physiology

    ERIC Educational Resources Information Center

    Skow, Rachel J.; Day, Trevor A.; Fuller, Jonathan E.; Bruce, Christina D.; Steinback, Craig D.

    2015-01-01

    The physiology of breath holding is complex, and voluntary breath-hold duration is affected by many factors, including practice, psychology, respiratory chemoreflexes, and lung stretch. In this activity, we outline a number of simple laboratory activities or classroom demonstrations that illustrate the complexity of the integrative physiology…

  5. Chromium(III) complexes of naturally occurring ligands

    NASA Astrophysics Data System (ADS)

    El-Shahawi, M. S.

    1995-02-01

    Chromium(III) complexes prepared from CrCl 3Py 3 and anhydrous CrCl 3 with L(-)-threonine, nicotinic acid, glycine, D(-)-penicillamine, L(-)-cysteine and L(-)-cystine have been characterized. The magnetic moments (3.4-4.05 B.M.) are close to the spin only value for a d3 chromium(III) ion in octahedral or pseudo octahedral symmetry. In the electronic spectra two sharp peaks are observed at (15.9-19.8) × 10 3 and (22.0-26.7) × 10 3 cm -1 and are assigned to d-d transitions in the pseudo octahedral configuration. The parameters ( Dq, B, β35) and the interelectronic repulsion parameter with the ionic charge, Z∗, are calculated and place the ligand in the middle of the spectrochemical series. In the circular dichroism spectra three Cotton effects are observed in the forbidden band of the optically active chelates and are assigned to the 2E( 2Eg), 2A 2( 2T 1g) and2E( 2T 1g) while that in the spin allowed band are a result of the splitting of the 4A 2g( 4T 2g) to 4A 1( 4T 2g) and4E( 4T 2g) transitions. The structure of threonine, cystine and cysteine chelates are likely to be fac since strong and well defined Cotton effects are observed. The Cotton effects of penicillamine chelates are weak suggesting formation of the mer structure. Prolonged heating or bubbling air through the solution of CrCl 3Py 3 containing L(-)-threonine, glycine or nicotinic acid for several hours enhances chromium(VI) formation.

  6. Photoluminescent red, green and blue monoliths of new Eu(III), Tb(III) and Y(III) complexes embedded in silica matrix

    NASA Astrophysics Data System (ADS)

    Stan, Corneliu S.; Popa, Marcel; Sutiman, Daniel; Horlescu, Petronela

    2014-07-01

    Large transparent photoluminescent monoliths were prepared by embedding newly synthesized Eu(III), Tb(III) and Y(III) complexes with 2-(1H-1,2,4-Triazol-3-yl)pyridine ligand in silica matrices through a modified sol-gel process. The remarkable luminescent properties of the free complexes were preserved in silica matrix, resulting in red, green and blue monoliths with a shape that may be tailored during the gelation process according to specific applications. Prior to embedment, the complexes prepared at 1/3 metal to ligand ratio were investigated through elemental analysis, thermal analysis, FT-IR, mass and fluorescence spectroscopy while the obtained silica monoliths were supplementary investigated through SEM and fluorescence spectroscopy. The emission peaks are located at 612 nm for the monolithic silica embedded Eu(III) complex, at 542 nm for the monolithic silica embedded Tb(III) complex and at 482 nm respectively for the silica monolith containing the Y(III) complex. Their excellent photoluminescent properties may recommend them as photonic conversion materials in various optoelectronic applications.

  7. Cerium(III), europium(III), and ytterbium(III) complexes with alcohol donor groups as chemical exchange saturation transfer agents for MRI.

    PubMed

    Huang, Ching-Hui; Morrow, Janet R

    2009-08-03

    Lanthanide(III) complexes of macrocycles 1,4,7,10-tetrakis(2-hydroxyethyl)-1,4,7,10-tetraazacyclododecane (THED) and (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane (S-THP) were studied as chemical exchange saturation transfer (CEST) agents for magnetic resonance imaging (MRI) applications. The four hyperfine-shifted alcohol protons of these Ln(III) complexes gave rise to a single (1)H resonance in wet d(3)-acetonitrile that was separated from the bulk water resonance (Delta omega) by 8 ppm (Ce), 2 ppm (Nd), 7 ppm (Eu), or 17 ppm (Yb). A CEST peak corresponding to the alcohol protons was observed for all Ln(THED)(3+) or Ln(S-THP)(3+) complexes except Nd(III) at low water concentrations (<1%). In 100% aqueous buffered solutions, the CEST hydroxyl peak is observed for the Eu(III), Ce(III), and Yb(III) complexes over a range of pH values. The optimal pH range for the CEST effect of each complex is related to the pK(a) of the hydroxyl/water ligands of the complex. Optimum pH values for the CEST effect from alcohol proton exchange are pH = 6.0 for Ce(S-THP)(3+), pH = 4.5 for Eu(THED)(3+), and pH = 3.0 for Yb(S-THP)(3+).

  8. 1,2,4-Diazaphospholide complexes of lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii): synthesis, X-ray structural characterization, and magnetic susceptibility studies.

    PubMed

    Zhao, Minggang; Wang, Lixia; Li, Pangpang; Ma, Jianping; Zheng, Wenjun

    2016-07-05

    A few heteroleptic, charge-separated heterobimetallic, and polymeric alkali metalate complexes of 1,2,4-diazaphospholide lanthanum(iii), cerium(iii), neodymium(iii), praseodymium(iii), and samarium(iii) were simply prepared via the metathesis reaction of MCl3 (THF)m (m = 1-2) and K[3,5-R2dp] ([3,5-R2dp](-) = 3,5-di-substituent-1,2,4-diazaphospholide; R = tBu, Ph) in a varied ratio (1 : 3, 1 : 4, and 1 : 5, respectively) at room temperature in tetrahydrofuran. All the complexes were fully characterized by (1)H, (13)C{(1)H}, (31)P{(1)H}, IR, and X-ray single crystal diffraction analysis despite their paramagnetism (excluding La(iii) complexes). The structures of the complexes were found to feature varied coordination modes. The magnetic properties of several compounds were studied by magnetic susceptibility, and the complexes presented the magnetic moments close to or lower than the theoretical values for the free ions in the trivalent oxidation states (Pr(3+), Nd(3+)).

  9. Redox reactions of V(III) and Cr(III)picolinate complexes in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Vinayakumar, C. K.; Dey, G. R.; Kishore, K.; Moorthy, P. N.

    1996-12-01

    Reactions of e aq-, H-atoms, OH, (CH 3) 2COH, and CO 2- radicals with V(III)picolinate and Cr(III)picolinate have been studied by the pulse radiolysis technique. The spectra of V(II)picolinate, V(IV)picolinate, Cr(II)picolinate, OH adduct of Cr(III)picolinate and Cr(IV)picolinate have been obtained and the rate constants of the reactions of various radicals with V(III) and Cr(III)picolinate have been determined. The implications of these results to the chemical decontamination of nuclear reactor systems are discussed.

  10. A spectrophotometric study of Nd(III), Sm(III) and Er(III) complexation in sulfate-bearing solutions at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Migdisov, Art. A.; Williams-Jones, A. E.

    2008-11-01

    The speciation of Nd(III), Sm(III), and Er(III) in sulfate-bearing solutions has been determined spectrophotometrically at temperatures from 25 to 250 °C and a pressure of 100 bars. The data obtained earlier on the speciation of Nd in sulfate-bearing solutions ( Migdisov et al., 2006) have been re-evaluated and corrected using a more appropriate activity model and are compared with the corresponding data for Sm(III) and Er(III) and new data for Nd(III). Based on this comparison, the dominant species in the solution are interpreted to be REESO4+ and REE(SO)2-, with the latter complex increasing in importance at higher temperature. Equilibrium constants were calculated for the following reactions:

  11. Highly luminescent charge-neutral europium(iii) and terbium(iii) complexes with tridentate nitrogen ligands.

    PubMed

    Senthil Kumar, Kuppusamy; Schäfer, Bernhard; Lebedkin, Sergei; Karmazin, Lydia; Kappes, Manfred M; Ruben, Mario

    2015-09-21

    We report on the synthesis of tridentate-nitrogen pyrazole-pyridine-tetrazole (L(1)H) and pyrazole-pyridine-triazole (L(2)H) ligands and their complexation with lanthanides (Ln = Gd(iii), Eu(iii) and Tb(iii)) resulting in stable, charge-neutral complexes Ln(L(1))3 and Ln(L(2))3, respectively. X-ray crystallographic analysis of the complexes with L(1) ligands revealed tricapped trigonal coordination geometry around the lanthanide ions. All complexes show bright photoluminescence (PL) in the solid state, indicating efficient sensitization of the lanthanide emission via the triplet states of the ligands. In particular, the terbium complexes show high PL quantum yields of 65 and 59% for L(1) and L(2), respectively. Lower PL efficiencies of the europium complexes (7.5 and 9%, respectively) are attributed to large energy gaps between the triplet states of the ligands and accepting levels of Eu(iii). The triplet state energy can be reduced by introducing an electron withdrawing (EW) group at the 4 position of the pyridine ring. Such substitution of L(1)H with a carboxylic ester (COOMe) EW group leads to a europium complex with increased PL quantum yield of 31%. A comparatively efficient PL of the complexes dissolved in ethanol indicates that the lanthanide ions are shielded against nonradiative deactivation via solvent molecules.

  12. Temperature dependence of blue phosphorescent cyclometalated Ir(III) complexes.

    PubMed

    Sajoto, Tissa; Djurovich, Peter I; Tamayo, Arnold B; Oxgaard, Jonas; Goddard, William A; Thompson, Mark E

    2009-07-22

    The photophysical properties for a series of facial (fac) cyclometalated Ir(III) complexes (fac-Ir(C--N)(3) (C--N = 2-phenylpyridyl (ppy), 2-(4,6-difluorophenyl)pyridyl (F2ppy), 1-phenylpyrazolyl (ppz), 1-(2,4-difluorophenyl)pyrazolyl) (F2ppz), and 1-(2-(9,9'-dimethylfluorenyl))pyrazolyl (flz)), fac-Ir(C--N)(2)(C--N') (C--N = ppz or F2ppz and C--N' = ppy or F2ppy), and fac-Ir(C--C')(3) (C--C' = 1-phenyl-3-methylbenzimidazolyl (pmb)) have been studied in dilute 2-methyltetrahydrofuran (2-MeTHF) solution in a temperature range of 77-378 K. Photoluminescent quantum yields (Phi) for the 10 compounds at room temperature vary between near zero and unity, whereas all emit with high efficiency at low temperature (77 K). The quantum yield for fac-Ir(ppy)(3) (Phi = 0.97) is temperature-independent. For the other complexes, the temperature-dependent data indicates that the luminescent efficiency is primarily determined by thermal deactivation to a nonradiative state. Activation energies and rate constants for both radiative and nonradiative processes were obtained using a Boltzmann analysis of the temperature-dependent luminescent decay data. Activation energies to the nonradiative state are found to range between 1600 and 4800 cm(-1). The pre-exponential factors for deactivation are large for complexes with C--N ligands (10(11)-10(13) s(-1)) and significantly smaller for fac-Ir(pmb)(3) (10(9) s(-1)). The kinetic parameters for decay and results from density functional theory (DFT) calculations of the triplet state are consistent with a nonradiative process involving Ir-N (Ir-C for fac-Ir(pmb)(3)) bond rupture leading to a five-coordinate species that has triplet metal-centered ((3)MC) character. Linear correlations are observed between the activation energy and the energy difference calculated for the emissive and (3)MC states. The energy level for the (3)MC state is estimated to lie between 21,700 and 24,000 cm(-1) for the fac-Ir(C--N)(3) complexes and at 28,000 cm(-1) for

  13. New yellow-emitting phosphorescent cyclometalated iridium(III) complex

    NASA Astrophysics Data System (ADS)

    Ivanov, P.; Tomova, R.; Petrova, P.; Stanimirov, S.; Petkov, I.

    2012-12-01

    We have synthesized a new yellow iridium complex Iridium(III) bis[2-phenylbenzothiazolato-N,C2']-(1-phenylicosane-1,3-dionate) (bt)2Ir(bsm), based on the benzothiazole derivative. The synthesized molecule was identified by 1H NMR and elemental analysis. The UV-Visible absorption and photoluminescence (PL) spectra of (bt)Ir2(bsm) in CH2Cl2 solution were found at 273 nm and 559 nm, respectively. The complex was used as a dopant into a hole-transporting layer (HTL) in a multilayered organic light emitting device (OLED) structure: ITO/doped-HTL/EL/ETL/M. ITO was a transparent anode of In2O3:SnO2, M- a metallic Al cathode, HTL- 4,4'-bis(9H-carbazol-9-yl)biphenyl (CBP) incorporated in poly(N-vinylcarbazole) (PVK) matrix, EL- electroluminescent layer of bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq) and ETL- electron-transporting layer of tris(8-hydroxyquinolinato)aluminum (Alq3). The electroluminescent (EL) spectra of OLEDs were basically the sum of the emissions of BAlq at 496 nm and the emission of (bt)2Ir(bsm) at 559 nm. With increasing (bt)2Ir(bsm) concentration, the relative electroluminescent intensity of greenish-blue emission (at 496 nm) decreased, while the yellow (at 559 nm) - increased and CIE coordinates of the device shifted from (0.21, 0.33) at 0 wt % to (0.40, 0.48) at 8 wt % of the dopant. It was found that OLED with 0.5 wt % (bt)2Ir(bsm) had the best performance and stable color chromaticity at various voltages.

  14. Enhancement of optical Faraday effect of nonanuclear Tb(III) complexes.

    PubMed

    Nakanishi, Takayuki; Suzuki, Yuki; Doi, Yoshihiro; Seki, Tomohiro; Koizumi, Hitoshi; Fushimi, Koji; Fujita, Koji; Hinatsu, Yukio; Ito, Hajime; Tanaka, Katsuhisa; Hasegawa, Yasuchika

    2014-07-21

    The effective magneto-optical properties of novel nonanuclear Tb(III) complexes with Tb-O lattice (specifically, [Tb9(sal-R)16(μ-OH)10](+)NO3(-), where sal-R = alkyl salicylate (R = -CH3 (Me), -C2H5 (Et), -C3H7 (Pr), or -C4H9 (Bu)) are reported. The geometrical structures of these nonanuclear Tb(III) complexes were characterized using X-ray single-crystal analysis and shape-measure calculation. Optical Faraday rotation was observed in nonanuclear Tb(III) complexes in the visible region. The Verdet constant per Tb(III) ion of the Tb9(sal-Me) complex is 150 times larger than that of general Tb(III) oxide glass. To understand their large Faraday rotation, electron paramagnetic resonance measurements of Gd(III) complexes were carried out. In this Report, the magneto-optical relation to the coordination geometry of Tb ions is discussed.

  15. Relationship between angiotensinogen, alpha 1-protease inhibitor elastase complex, antithrombin III and C-reactive protein in septic ARDS.

    PubMed

    Hilgenfeldt, U; Kellermann, W; Kienapfel, G; Jochum, M

    1990-01-01

    The time-course of plasma angiotensinogen (Ao), elastase-alpha 1-protease inhibitor complex (EL alpha 1PI), antithrombin III (AT III) and C-reactive protein (CRP) have been investigated of six patients suffering from adult respiratory distress syndrome (ARDS). The total plasma Ao level (active and inactive Ao) varied in individuals but was increased up to five-fold. An increasing amount of inactive Ao is found. From the beginning of their stay in the intensive care unit up to five days half of the patients displayed a positive correlation between the plasma CRP and Ao level. The CRP and Ao values were either not or were negatively correlated with the AT III values. In contrast plasma Ao and AT III levels in all patients were positively correlated during a particular period in the subsequent phase of the disease, where there was no or a negative correlation with CRP. The two acute phase reactants CRP and EL alpha 1PI were only correlated in two patients at the beginning of the disease. The markedly increased plasma level at the beginning of the inflammatory disease indicates that Ao is an acute phase reactant, and this is supported by the parallel changes in plasma CRP and Ao levels during the early days of ARDS. The relationship between the plasma levels of Ao and AT III for more than fourteen days suggests similar regulation of these members of the serpin family after termination of the acute-phase.

  16. Mitochondrial respiratory complex I probed by delayed luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Baran, Irina; Ionescu, Diana; Privitera, Simona; Scordino, Agata; Mocanu, Maria Magdalena; Musumeci, Francesco; Grasso, Rosaria; Gulino, Marisa; Iftime, Adrian; Tofolean, Ioana Teodora; Garaiman, Alexandru; Goicea, Alexandru; Irimia, Ruxandra; Dimancea, Alexandru; Ganea, Constanta

    2013-12-01

    The role of mitochondrial complex I in ultraweak photon-induced delayed photon emission [delayed luminescence (DL)] of human leukemia Jurkat T cells was probed by using complex I targeting agents like rotenone, menadione, and quercetin. Rotenone, a complex I-specific inhibitor, dose-dependently increased the mitochondrial level of reduced nicotinamide adenine dinucleotide (NADH), decreased clonogenic survival, and induced apoptosis. A strong correlation was found between the mitochondrial levels of NADH and oxidized flavin mononucleotide (FMNox) in rotenone-, menadione- and quercetin-treated cells. Rotenone enhanced DL dose-dependently, whereas quercetin and menadione inhibited DL as well as NADH or FMNox. Collectively, the data suggest that DL of Jurkat cells originates mainly from mitochondrial complex I, which functions predominantly as a dimer and less frequently as a tetramer. In individual monomers, both pairs of pyridine nucleotide (NADH/reduced nicotinamide adenine dinucleotide phosphate) sites and flavin (FMN-a/FMN-b) sites appear to bind cooperatively their specific ligands. Enhancement of delayed red-light emission by rotenone suggests that the mean time for one-electron reduction of ubiquinone or FMN-a by the terminal Fe/S center (N2) is 20 or 284 μs, respectively. All these findings suggest that DL spectroscopy could be used as a reliable, sensitive, and robust technique to probe electron flow within complex I in situ.

  17. Evaluation of the In Vivo and In Vitro Effects of Fructose on Respiratory Chain Complexes in Tissues of Young Rats

    PubMed Central

    Macongonde, Ernesto António; Vilela, Thais Ceresér; Scaini, Giselli; Gonçalves, Cinara Ludvig; Ferreira, Bruna Klippel; Costa, Naithan Ludian Fernandes; de Oliveira, Marcos Roberto; Avila, Silvio; Streck, Emilio Luiz; Ferreira, Gustavo Costa; Schuck, Patrícia Fernanda

    2015-01-01

    Hereditary fructose intolerance (HFI) is an autosomal-recessive disorder characterized by fructose and fructose-1-phosphate accumulation in tissues and biological fluids of patients. This disease results from a deficiency of aldolase B, which metabolizes fructose in the liver, kidney, and small intestine. We here investigated the effect of acute fructose administration on the activities of mitochondrial respiratory chain complexes, succinate dehydrogenase (SDH), and malate dehydrogenase (MDH) in cerebral cortex, liver, kidney, and skeletal muscle of male 30-day-old Wistar rats. The rats received subcutaneous injection of sodium chloride (0.9%; control group) or fructose solution (5 μmol/g; treated group). One hour later, the animals were euthanized and the cerebral cortex, liver, kidney, and skeletal muscle were isolated and homogenized for the investigations. Acute fructose administration increased complex I-III activity in liver. On the other hand, decreased complexes II and II-III activities in skeletal muscle and MDH in kidney were found. Interestingly, none of these parameters were affected in vitro. Our present data indicate that fructose administration elicits impairment of mitochondrial energy metabolism, which may contribute to the pathogenesis of the HFI patients. PMID:26770008

  18. Mitochondrial reactive oxygen species production and respiratory complex activity in rats with pressure overload-induced heart failure

    PubMed Central

    Schwarzer, Michael; Osterholt, Moritz; Lunkenbein, Anne; Schrepper, Andrea; Amorim, Paulo; Doenst, Torsten

    2014-01-01

    We investigated the impact of cardiac reactive oxygen species (ROS) during the development of pressure overload-induced heart failure. We used our previously described rat model where transverse aortic constriction (TAC) induces compensated hypertrophy after 2 weeks, heart failure with preserved ejection fraction at 6 and 10 weeks, and heart failure with systolic dysfunction after 20 weeks. We measured mitochondrial ROS production rates, ROS damage and assessed the therapeutic potential of in vivo antioxidant therapies. In compensated hypertrophy (2 weeks of TAC) ROS production rates were normal at both mitochondrial ROS production sites (complexes I and III). Complex I ROS production rates increased with the appearance of diastolic dysfunction (6 weeks of TAC) and remained high thereafter. Surprisingly, maximal ROS production at complex III peaked at 6 weeks of pressure overload. Mitochondrial respiratory capacity (state 3 respiration) was elevated 2 and 6 weeks after TAC, decreased after this point and was significantly impaired at 20 weeks, when contractile function was also impaired and ROS damage was found with increased hydroxynonenal. Treatment with the ROS scavenger α-phenyl-N-tert-butyl nitrone or the uncoupling agent dinitrophenol significantly reduced ROS production rates at 6 weeks. Despite the decline in ROS production capacity, no differences in contractile function between treated and untreated animals were observed. Increased ROS production occurs early in the development of heart failure with a peak at the onset of diastolic dysfunction. However, ROS production may not be related to the onset of contractile dysfunction. PMID:24951621

  19. Evaluation of the In Vivo and In Vitro Effects of Fructose on Respiratory Chain Complexes in Tissues of Young Rats.

    PubMed

    Macongonde, Ernesto António; Vilela, Thais Ceresér; Scaini, Giselli; Gonçalves, Cinara Ludvig; Ferreira, Bruna Klippel; Costa, Naithan Ludian Fernandes; de Oliveira, Marcos Roberto; Avila Junior, Silvio; Streck, Emilio Luiz; Ferreira, Gustavo Costa; Schuck, Patrícia Fernanda

    2015-01-01

    Hereditary fructose intolerance (HFI) is an autosomal-recessive disorder characterized by fructose and fructose-1-phosphate accumulation in tissues and biological fluids of patients. This disease results from a deficiency of aldolase B, which metabolizes fructose in the liver, kidney, and small intestine. We here investigated the effect of acute fructose administration on the activities of mitochondrial respiratory chain complexes, succinate dehydrogenase (SDH), and malate dehydrogenase (MDH) in cerebral cortex, liver, kidney, and skeletal muscle of male 30-day-old Wistar rats. The rats received subcutaneous injection of sodium chloride (0.9%; control group) or fructose solution (5 μmol/g; treated group). One hour later, the animals were euthanized and the cerebral cortex, liver, kidney, and skeletal muscle were isolated and homogenized for the investigations. Acute fructose administration increased complex I-III activity in liver. On the other hand, decreased complexes II and II-III activities in skeletal muscle and MDH in kidney were found. Interestingly, none of these parameters were affected in vitro. Our present data indicate that fructose administration elicits impairment of mitochondrial energy metabolism, which may contribute to the pathogenesis of the HFI patients.

  20. Magnetic interactions in CuII-LnIII cyclic tetranuclear complexes: is it possible to explain the occurrence of SMM behavior in CuII-TbIII and CuII-DyIII complexes?

    PubMed

    Hamamatsu, Takefumi; Yabe, Kazuya; Towatari, Masaaki; Osa, Shutaro; Matsumoto, Naohide; Re, Nazzareno; Pochaba, Andrzej; Mrozinski, Jerzy; Gallani, Jean-Louis; Barla, Alessandro; Imperia, Paolo; Paulsen, Carley; Kappler, Jean-Paul

    2007-05-28

    An extensive series of tetranuclear CuII2LnIII2 complexes [CuIILLnIII(hfac)2]2 (with LnIII being all lanthanide(III) ions except for the radioactive PmIII) has been prepared in order to investigate the nature of the CuII-LnIII magnetic interactions and to try to answer the following question: What makes the CuII2TbIII2 and CuII2DyIII2 complexes single molecule magnets while the other complexes are not? All the complexes within this series possess a similar cyclic tetranuclear structure, in which the CuII and LnIII ions are arrayed alternately via bridges of ligand complex (CuIIL). Regular SQUID magnetometry measurements have been performed on the series. The temperature-dependent magnetic susceptibilities from 2 to 300 K and the field-dependent magnetizations from 0 to 5 T at 2 K have been measured for the CuII2LnIII2 and NiII2LnIII2 complexes, with the NiII2LnIII2 complex containing diamagnetic NiII ions being used as a reference for the evaluation of the CuII-LnIII magnetic interactions. These measurements have revealed that the interactions between CuII and LnIII ions are very weakly antiferromagnetic if Ln=Ce, Nd, Sm, Yb, ferromagnetic if Ln=Gd, Tb, Dy, Ho, Er, Tm, and negligible if Ln=La, Eu, Pr, Lu. With the same goal of better understanding the evolution of the intramolecular magnetic interactions, X-ray magnetic circular dichroism (XMCD) has also been measured on CuII2TbIII2, CuII2DyIII2, and NiII2TbIII2 complexes, either at the L- and M-edges of the metal ions or at the K-edge of the N and O atoms. Last, the CuII2TbIII2 complex exhibiting SMM behavior has received a closer examination of its low temperature magnetic properties down to 0.1 K. These particular measurements have revealed the unusual very slow setting-up of a 3D order below 0.6 K.

  1. Thiocyanato Chromium (III) Complexes: Separation by Paper Electrophoresis and Estimate of Stability Constants

    ERIC Educational Resources Information Center

    Larsen, Erik; Eriksen, J.

    1975-01-01

    Describes an experiment wherein the student can demonstrate the existence of all the thiocyanato chromium complexes, estimate the stepwise formation constants, demonstrate the robustness of chromium III complexes, and show the principles of paper electrophoresis. (GS)

  2. Cyclometalated iridium(III) polypyridine dibenzocyclooctyne complexes as the first phosphorescent bioorthogonal probes.

    PubMed

    Lo, Kenneth Kam-Wing; Chan, Bruce Ting-Ngok; Liu, Hua-Wei; Zhang, Kenneth Yin; Li, Steve Po-Yam; Tang, Tommy Siu-Ming

    2013-05-14

    We report the synthesis, photophysical behavior, and biological properties of new cyclometalated iridium(iii) polypyridine complexes appended with a dibenzocyclooctyne (DIBO) moiety; these complexes have been utilized as the first phosphorescent bioorthogonal probes for azide-modified biomolecules.

  3. Thiocyanato Chromium (III) Complexes: Separation by Paper Electrophoresis and Estimate of Stability Constants

    ERIC Educational Resources Information Center

    Larsen, Erik; Eriksen, J.

    1975-01-01

    Describes an experiment wherein the student can demonstrate the existence of all the thiocyanato chromium complexes, estimate the stepwise formation constants, demonstrate the robustness of chromium III complexes, and show the principles of paper electrophoresis. (GS)

  4. Reactions and structural characterization of gold(III) complexes with amino acids, peptides and proteins.

    PubMed

    Glišić, Biljana Đ; Rychlewska, Urszula; Djuran, Miloš I

    2012-06-21

    The present review article highlights recent findings in the field of gold(III) complexes with amino acids, peptides and proteins. The first section of this article provides an overview of the gold(III) reactions with amino acids, such as glycine, alanine, histidine, cysteine and methionine. The second part of the review is mainly focused on the results achieved in the mechanistic studies of the reactions between gold(III) and different peptides and structural characterization of gold(III)-peptide complexes as the final products in these reactions. The last section of this article deals with the reactions of gold(III) complexes with proteins as primary targets for cytotoxic gold compounds. Systematic summaries of these results contribute to the future development of gold(III) complexes as potential antitumor agents and also have importance in relation to the severe toxicity of gold-based drugs.

  5. [Recommendations for respiratory support in the newborn (iii). Surfactant and nitric oxide].

    PubMed

    Castillo Salinas, F; Elorza Fernández, D; Gutiérrez Laso, A; Moreno Hernando, J; Bustos Lozano, G; Gresa Muñoz, M; López de Heredia Goya, J; Aguar Carrascosa, M; Miracle Echegoyen, X; Fernández Lorenzo, J R; Serrano, M M; Concheiro Guisan, A; Carrasco Carrasco, C; Comuñas Gómez, J J; Moral Pumarega, M T; Sánchez Torres, A M; Franco, M L

    2015-11-01

    The recommendations included in this document will be part a series of updated reviews of the literature on respiratory support in the newborn infant. These recommendations are structured into twelve modules, and in this work module 7 is presented. Each module is the result of a consensus process including all members of the Surfactant and Respiratory Group of the Spanish Society of Neonatology. They represent a summary of the published papers on each specific topic, and of the clinical experience of each one of the members of the group.

  6. Polymer thin films containing Eu(III) complex as lanthanide lasing medium

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yasuchika; Wada, Yuji; Yanagida, Shozo; Kawai, Hideki; Yasuda, Naoki; Nagamura, Toshihiko

    2003-10-01

    Direct evidence of lanthanide(III) lasing using Eu(III) complex in polymer thin films (threshold level <0.05 mJ) is reported. The thin film consists of polystyrene containing Eu(III) complexes based on two criteria: (1) Higher emission quantum yield of Eu(III) complexes, which increases the rs (energy density), and (2) faster radiation rate at large B (Einstein coefficient). The microcavity was constructed by coating a glass substrate with a film having a high refractive index. The film thickness was found to be 1.71 mm. The threshold level for laser transmission was found to be <0.05 mJ.

  7. Modulation of homochiral Dy(III) complexes: single-molecule magnets with ferroelectric properties.

    PubMed

    Li, Xi-Li; Chen, Chun-Lai; Gao, Yu-Liang; Liu, Cai-Ming; Feng, Xiang-Li; Gui, Yang-Hai; Fang, Shao-Ming

    2012-11-12

    Homochiral Dy(III) complexes: by changing the ligand-to-metal ratio, enantiomeric pairs of a Dy(III) complex of different nuclearity could be obtained. The mono- and dinuclear complexes exhibit characteristics of single-molecule magnets and different slow magnetic relaxation processes. In addition, the dinuclear complexes exhibit ferroelectric behavior, thus representing the first chiral polynuclear lanthanide-based single-molecule magnets with ferroelectric properties.

  8. Methods to increase the luminescence of lanthanide (III) macrocyclic complexes

    NASA Astrophysics Data System (ADS)

    Quagliano, John R.; Leif, Robert C.; Vallarino, Lidia M.; Williams, Steven A.

    2000-04-01

    Simultaneous detection of both a Eu(III) and a Sm(III) Quantum Dye is now possible because the enhanced luminescence of the Eu(III) and Sm(III) macrocycles occurs in the same solution and with excitation at the same wavelengths between 350 to 370 nm. Since DAPI is also excited between 350 to 370 nm, it is possible to use common excitation optics and a single dichroic mirror for measuring two molecular species and DNA. The narrow emissions of these macrocycles can be detected with negligible overlap between themselves or with DAPI-stained DNA. This will permit precise pixel by pixel ratio measurements of the Eu(III) macrocycle to Sm(III) macrocycle, and of each macrocycle to DNA> This technology should be applicable to antibodies, FISH, comparative genomic hybridization, and chromosome painting. Cofluorescence of the Tb(III)-macrocycle has also been obtained under different conditions. The luminescence of these lanthanide macrocycles can be observed with conventional fluorescence instrumentation previously unattainable low levels. Thus, it will be possible to employ narrow bandwidth lanthanide luminescent tags to identify three molecular species with a conventional microscope.

  9. Preparation and characterization of a novel Astragalus membranaceus polysaccharide-iron (III) complex.

    PubMed

    Lu, Qi; Xu, Lei; Meng, Yongbin; Liu, Ying; Li, Jian; Zu, Yuangang; Zhu, Minghua

    2016-12-01

    Astragalus membranaceus polysaccharide-iron (III) complex (APS-iron) was synthesized and characterized. Based on single factor and response surface optimization experiments of APS-iron (III) complex synthesis, the optimum conditions of APS-iron (III) complex were obtained as follows: the reaction temperature 89.46°C, pH 8.16, reaction time 46.04min and ratio of catalyst to APS 0.75, respectively. The reaction temperature was the most significant factor, followed by pH, reaction time and the ratio of catalyst to APS in the four reaction parameters. The highest iron content (19.32%) of APS-iron (III) complex was obtained at the optimum conditions, which was characterized by fourier transform infrared (FTIR), scanning electron microscopy (SEM), antioxidant activities of the APS-iron (III) complex and iron release of APS-iron (III) complex in vitro assay. The results indicated the APS-iron (III) complex had good bioavailability and antioxidant activities in vitro assays. So, it was potential for APS-iron (III) complex as a candidate for iron supplements.

  10. Synthesis, characterization and DNA-binding properties of La(III) complex of chrysin.

    PubMed

    Zeng, Yi-Bo; Yang, Nan; Liu, Wei-Sheng; Tang, Ning

    2003-11-01

    A novel La(III) complex of chrysin (5,7-dihydroxyflavone) was synthesized and characterized by UV, IR, 1H NMR, thermogravimetry/differential thermal analysis (TG/DTA) and elementary analyses. The interactions of the La(III) complex and chrysin with calf thymus DNA were investigated by spectrophotometric methods and viscosity measurements. The intrinsic binding constants of La(III) complex and chrysin are 1.29 x 10(6) and 5.44 x 10(5) M(-1), respectively. Experimental results indicated that La(III) complex and chrysin can both bind to DNA by intercalation modes, but the binding affinity of La(III) complex is much higher than that of chrysin. Comparative antitumor activities of La(III) complex and chrysin were tested by MTT and SRB methods. The results show that at the concentration of 10 microM for chrysin and La(III) complex, the inhibitory ratios of La(III) complex against the tested tumor cells were higher than those of chrysin.

  11. Phosphorescent Imaging of Living Cells Using a Cyclometalated Iridium(III) Complex

    PubMed Central

    Ma, Dik-Lung; Zhong, Hai-Jing; Fu, Wai-Chung; Chan, Daniel Shiu-Hin; Kwan, Hiu-Yee; Fong, Wang-Fun; Chung, Lai-Hon; Wong, Chun-Yuen; Leung, Chung-Hang

    2013-01-01

    A cell permeable cyclometalated iridium(III) complex has been developed as a phosphorescent probe for cell imaging. The iridium(III) solvato complex [Ir(phq)2(H2O]2)] preferentially stains the cytoplasm of both live and dead cells with a bright luminescence. PMID:23457478

  12. Photofunctional triplet excited states of cyclometalated Ir(III) complexes: beyond electroluminescence.

    PubMed

    You, Youngmin; Nam, Wonwoo

    2012-11-07

    The development of cyclometalated Ir(III) complexes has enabled important breakthroughs in electroluminescence because such complexes permit the efficient population of triplet excited states that give rise to luminescent transitions. The triplet states of Ir(III) complexes are advantageous over those of other transition metal complexes in that their electronic transitions and charge-transfer characteristics are tunable over wide ranges. These favorable properties suggest that Ir(III) complexes have significant potential in a variety of photofunctions other than electroluminescence. In this critical review, we describe recent photonic applications of novel Ir(III) complexes. Ir(III) complexes have been shown to affect the exciton statistics in the active layers of organic photovoltaic cells, thereby improving the photon-to-current conversion efficiencies. Nonlinear optical applications that take advantage of the strong charge-transfer properties of triplet transitions are also discussed. The tunability of the electrochemical potentials facilitates the development of efficient photocatalysis in the context of water photolysis or organic syntheses. The photoredox reactivities of Ir(III) complexes have been employed in studies of charge migration along DNA chains. The photoinduced cytotoxicity of Ir(III) complexes on live cells suggests that the complexes may be useful in photodynamic therapy. Potential biological applications of the complexes include phosphorescence labeling and sensing. Intriguing platforms based on cyclometalated Ir(III) complexes potentially provide novel protein tagging and ratiometric detection. We envision that future research into the photofunctionality of Ir(III) complexes will provide important breakthroughs in a variety of photonic applications.

  13. Fluorescence and DNA-binding properties of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline

    NASA Astrophysics Data System (ADS)

    Khorasani-Motlagh, Mozhgan; Noroozifar, Meissam; Mirkazehi-Rigi, Sohaila

    2011-09-01

    The binding of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline, [M(phen) 2Cl 3·OH 2] (M = Nd ( 1), Pr ( 2)), to DNA has been investigated by absorption, emission, and viscosity measurements. The complexes show absorption decreasing in charge transfer band, fluorescence decrement when bound to DNA. The binding constant Kb has been determined by absorption measurement for both complexes and found to be (6.76 ± 0.12) × 10 4 for 1 and (1.83 ± 0.15) × 10 4 M -1, for 2. The fluorescence of [M(phen) 2Cl 3·OH 2] (M = Nd ( 1), Pr ( 2)) has been studied in detail. The results of fluorescence titration reveal that DNA has the strong ability to quenching the intrinsic fluorescence of Nd(III) and Pr(III) complexes through the static quenching procedure. The binding site number n, apparent binding constant Kb and the Stern-Volmer constant kSV are determined. Thermodynamic parameters, enthalpy change (Δ H°) and entropy change (Δ S°), are calculated according to relevant fluorescent data and Van't Hoff equation. The experimental data suggest that the complexes bind to DNA by non-intercalative mode. Major groove binding is the preferred mode of interaction for [M(phen) 2Cl 3·OH 2] (M = Nd ( 1), Pr ( 2)) with DNA.

  14. Fluorescence and DNA-binding properties of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline.

    PubMed

    Khorasani-Motlagh, Mozhgan; Noroozifar, Meissam; Mirkazehi-Rigi, Sohaila

    2011-09-01

    The binding of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline, [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)), to DNA has been investigated by absorption, emission, and viscosity measurements. The complexes show absorption decreasing in charge transfer band, fluorescence decrement when bound to DNA. The binding constant Kb has been determined by absorption measurement for both complexes and found to be (6.76±0.12)×10(4) for 1 and (1.83±0.15)×10(4)M(-1), for 2. The fluorescence of [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) has been studied in detail. The results of fluorescence titration reveal that DNA has the strong ability to quenching the intrinsic fluorescence of Nd(III) and Pr(III) complexes through the static quenching procedure. The binding site number n, apparent binding constant Kb and the Stern-Volmer constant kSV are determined. Thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), are calculated according to relevant fluorescent data and Van't Hoff equation. The experimental data suggest that the complexes bind to DNA by non-intercalative mode. Major groove binding is the preferred mode of interaction for [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) with DNA.

  15. Complexation of Am(III) and Nd(III) by 1,10-Phenanthroline-2,9-Dicarboxylic Acid

    SciTech Connect

    Ogden, Mark D.; Sinkov, Sergey I.; Nilsson, Mikael; Lumetta, Gregg J.; Hancock, Robert D.; Nash, Ken L.

    2013-01-01

    The complexant 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) is a planar tetradentate ligand that is more preorganized for metal complexation than its unconstrained analogue ethylendiiminodiacetic acid (EDDA). Furthermore, the backbone nitrogen atoms of PDA are aromatic, hence are softer than the aliphatic amines of EDDA. It has been hypothesized that PDA will selectively bond to trivalent actinides over lanthanides. In this report, the results of spectrophotometric studies of the complexation of Nd(III) and Am(III) by PDA are reported. Because the complexes are moderately stable, it was necessary to conduct these titrations using competitive equilibrium methods, competitive cation omplexing between PDA and diethylenetriaminepentaacetic acid, and competition between ligand protonation and complex formation. Stability constants and ligand protonation constants were determined at 0.1 mol/L ionic strength and at 0.5 mol/L ionic strength nitrate media at 21 ± 1 C. The stability constants are lower than those predicted from first principles and speciation calculations indicate that Am(III) selectivity over Nd(III) is less than that exhibited by 1,10-phenanthroline.

  16. Soluble Mn(III)-L complexes are abundant in oxygenated waters and stabilized by humic ligands

    NASA Astrophysics Data System (ADS)

    Oldham, Véronique E.; Mucci, Alfonso; Tebo, Bradley M.; Luther, George W.

    2017-02-01

    Dissolved Mn (dMnT) is thought to be dominated by metastable Mn(II) in the presence of oxygen, as the stable form is insoluble Mn(IV). We show, for the first time, that Mn(III) is also stable as a soluble species in the oxygenated water column, when stabilized by organic ligands as Mn(III)-L complexes. We measured Mn(III)-L complexes in the oxygenated waters of a coastal fjord and a hemipelagic system where they make up to 86% of the dMnT. Although Mn(III) forms similar complexes to Fe(III), unlike most of the analogous Fe(III)-L complexes, the Mn(III)-L complexes are not colloidal, as they pass through both 0.20 μm and 0.02 μm filters. Depending on the kinetic stability of the Mn(III) complexes and the microbial community of a given system, these Mn(III)-L complexes are capable of donating or accepting electrons and may therefore serve as both reductants or oxidants, can be biologically available, and can thus participate in a multitude of redox reactions and biogeochemical processes. Furthermore, sample acidification experiments revealed that Mn(III) binding to humic ligands is responsible for up to 100% of this complexation, which can influence the formation of other metal complexes including Fe(III) and thus impact nutrient availability and uptake. Hence, humic ligands may play a greater role in dissolved Mn transport from coastal areas to the ocean than previously thought.

  17. Calculation of genomic predicted transmitting abilities for bovine respiratory disease complex in Holsteins

    USDA-ARS?s Scientific Manuscript database

    Bovine Respiratory Disease Complex is a disease that is very costly to the dairy industry. Genomic selection may be an effective tool to improve host resistance to the pathogens that cause this disease. Use of genomic predicted transmitting abilities (GPTA) for selection has had a dramatic effect on...

  18. Closed Genome Sequences of Seven Histophilus somni Isolates from Beef Calves with Bovine Respiratory Disease Complex

    PubMed Central

    Harhay, Dayna M.; Bono, James L.; Smith, Timothy P. L.; Capik, Sarah F.; DeDonder, Keith D.; Apley, Michael D.; Lubbers, Brian V.; White, Bradley J.; Larson, Robert L.

    2017-01-01

    ABSTRACT Histophilus somni is a fastidious Gram-negative opportunistic pathogenic Pasteurellaceae that affects multiple organ systems and is one of the principal bacterial species contributing to bovine respiratory disease complex (BRDC) in feed yard cattle. Here, we present seven closed genome sequences isolated from three beef calves showing sign of BRDC. PMID:28983006

  19. MICOS coordinates with respiratory complexes and lipids to establish mitochondrial inner membrane architecture

    PubMed Central

    Friedman, Jonathan R; Mourier, Arnaud; Yamada, Justin; McCaffery, J Michael; Nunnari, Jodi

    2015-01-01

    The conserved MICOS complex functions as a primary determinant of mitochondrial inner membrane structure. We address the organization and functional roles of MICOS and identify two independent MICOS subcomplexes: Mic27/Mic10/Mic12, whose assembly is dependent on respiratory complexes and the mitochondrial lipid cardiolipin, and Mic60/Mic19, which assembles independent of these factors. Our data suggest that MICOS subcomplexes independently localize to cristae junctions and are connected via Mic19, which functions to regulate subcomplex distribution, and thus, potentially also cristae junction copy number. MICOS subunits have non-redundant functions as the absence of both MICOS subcomplexes results in more severe morphological and respiratory growth defects than deletion of single MICOS subunits or subcomplexes. Mitochondrial defects resulting from MICOS loss are caused by misdistribution of respiratory complexes in the inner membrane. Together, our data are consistent with a model where MICOS, mitochondrial lipids and respiratory complexes coordinately build a functional and correctly shaped mitochondrial inner membrane. DOI: http://dx.doi.org/10.7554/eLife.07739.001 PMID:25918844

  20. Closed genomes of seven histophilus somni isolates from beef calves with bovine respiratory disease complex

    USDA-ARS?s Scientific Manuscript database

    Histophilus somni is a fastidious gram-negative opportunistic pathogenic Pasteurellacea that affects multiple organ systems and is one of the principle bacterial species contributing to bovine respiratory disease complex (BRDC) in feed yard cattle. Here we present seven closed genomes isolated from...

  1. Differential inhibition of mitochondrial respiratory complexes by inhalation of combustion smoke and carbon monoxide, in vivo, in the rat brain.

    PubMed

    Lee, Heung M; Hallberg, Lance M; Greeley, George H; Englander, Ella W

    2010-08-01

    Combustion smoke contains gases and particulates, which act via hypoxia and cytotoxicity producing mechanisms to injure cells and tissues. While carbon monoxide (CO) is the major toxicant in smoke, its toxicity is exacerbated in the presence of other compounds. Here, we examined modulations of mitochondrial and cytosolic energy metabolism by inhalation of combustion smoke versus CO, in vivo, in the rat brain. Measurements revealed reduced activities of respiratory chain (RC) complexes, with greater inhibition by smoke than equivalent CO in ambient air. In the case of RC complex IV, inhibition by CO and smoke was similar--suggesting that complex IV inhibition is primarily by the action of CO. In contrast, inhibition of complexes I and III was greater by smoke. Increases in cytosolic lactate dehydrogenase and pyruvate kinase activities accompanied inhibition of RC complexes, likely reflecting compensatory increases in cytosolic energy production. Together, the data provide new insights into the mechanisms of smoke inhalation-induced perturbations of brain energetics, which impact neuronal function and contribute to the development of neuropathologies in survivors of exposures to CO and combustion smoke.

  2. Mitochondrial Respiratory Complex I: Structure, Function and Implication in Human Diseases

    PubMed Central

    Sharma, Lokendra K.; Lu, Jianxin; Bai, Yidong

    2016-01-01

    Mitochondria are ubiquitous organelles in eukaryotic cells whose primary function is to generate energy supplies in the form of ATP through oxidative phosphorylation. As the entry point for most electrons into the respiratory chain, NADH:ubiquinone oxidoreductase, or complex I, is the largest and least understood component of the mitochondrial oxidative phosphorylation system. Substantial progress has been made in recent years in understanding its subunit composition, its assembly, the interaction among complex I and other respiratory components, and its role in oxidative stress and apoptosis. This review provides an updated overview of the structure of complex I, as well as its cellular functions, and discusses the implication of complex I dysfunction in various human diseases. PMID:19355884

  3. Spectroscopic studies on the interaction of morin-Eu(III) complex with calf thymus DNA

    NASA Astrophysics Data System (ADS)

    Zhang, Guowen; Guo, Jinbao; Pan, Junhui; Chen, Xiuxia; Wang, Junjie

    2009-04-01

    The interaction between morin-Eu(III) complex and calf thymus DNA in physiological buffer (pH 7.4) was investigated using UV-vis spectrophotometry, fluorescence spectroscopy, viscosity measurements and DNA melting techniques. Hypochromicity and red shift of the absorption spectra of morin-Eu(III) complex were observed in the presence of DNA, and the fluorescence intensity of morin-Eu(III) complex was greatly enhanced with the addition of DNA. Moreover, fluorescence quenching and blue shift of the emission peak were seen in the DNA-ethidium bromide (EB) system when morin-Eu(III) complex was added. The relative viscosity of DNA increased with the addition of morin-Eu(III) complex, whereas the value of melting temperature of DNA-EB system decreased in the presence of morin-Eu(III) complex. All these results indicated that morin-Eu(III) complex can bind to DNA and the major binding mode is intercalative binding. The 3:1 morin:Eu(III) complex (estimated binding constant = 2.36 × 10 6 L mol -1) is stabilized by intercalation into the DNA. The calculated binding constants of morin-Eu(III) complex with DNA at 292, 301 and 310 K were 7.47 × 10 4, 8.89 × 10 4 and 1.13 × 10 5 L mol -1, respectively. The thermodynamic parameters were also obtained: Δ H θ was 20.14 kJ mol -1 > 0 and Δ S θ was 161.70 J mol -1 K -1 > 0, suggesting that hydrophobic force plays a major role in the binding of morin-Eu(III) complex to DNA.

  4. Modeling rare earth complexes: Sparkle/AM1 parameters for thulium (III)

    NASA Astrophysics Data System (ADS)

    Freire, Ricardo O.; Rocha, Gerd B.; Simas, Alfredo M.

    2005-08-01

    The Sparkle/AM1 model, recently defined for Eu(III), Gd(III) and Tb(III) [R.O. Freire, G.B. Rocha, A.M., Simas, Inorg. Chem. 44 (2005) 3299], is extended to Tm(III). A set of 15 structures of high crystallographic quality from the Cambridge Crystallographic Database, with ligands chosen to be representative of all complexes with nitrogen or oxygen directly bonded to the Tm(III) ion, was used as a training set. For the 15 complexes, the Sparkle/AM1 unsigned mean error, for all interatomic distances between the Tm(III) ion and the oxygen or nitrogen ligand atoms of the first sphere of coordination, is 0.07 Å, a level of accuracy useful for luminescent complex design.

  5. Loss of Pink1 modulates synaptic mitochondrial bioenergetics in the rat striatum prior to motor symptoms: concomitant complex I respiratory defects and increased complex II-mediated respiration.

    PubMed

    Stauch, Kelly L; Villeneuve, Lance M; Purnell, Phillip R; Ottemann, Brendan M; Emanuel, Katy; Fox, Howard S

    2016-12-01

    Mutations in PTEN-induced putative kinase 1 (Pink1), a mitochondrial serine/threonine kinase, cause a recessive inherited form of Parkinson's disease (PD). Pink1 deletion in rats results in a progressive PD-like phenotype, characterized by significant motor deficits starting at 4 months of age. Despite the evidence of mitochondrial dysfunction, the pathogenic mechanism underlying disease due to Pink1-deficiency remains obscure. Striatal synaptic mitochondria from 3-month-old Pink1-deficient rats were characterized using bioenergetic and mass spectroscopy (MS)-based proteomic analyses. Striatal synaptic mitochondria from Pink1-deficient rats exhibit decreased complex I-driven respiration and increased complex II-mediated respiration compared with wild-type rats. MS-based proteomics revealed 69 of the 811 quantified mitochondrial proteins were differentially expressed between Pink1-deficient rats and controls. Down-regulation of several electron carrier proteins, which shuttle electrons to reduce ubiquinone at complex III, in the Pink1-knockouts suggests disruption of the linkage between fatty acid, amino acid, and choline metabolism and the mitochondrial respiratory system. These results suggest that complex II activity is increased to compensate for loss of electron transfer mechanisms due to reduced complex I activity and loss of electron carriers within striatal nerve terminals early during disease progression. This may contribute to the pathogenesis of PD. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Photoluminescence studies on the complexation of Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitrate medium

    NASA Astrophysics Data System (ADS)

    Pathak, P. N.; Mohapatra, M.; Godbole, S. V.

    2013-11-01

    UREX process has been proposed for selective extraction of U(VI) and Tc(VII) from nitric acid medium (∼1 M HNO3) using tri-n-butyl phosphate (TBP) as extractant and retaining Pu, Np and fission products in the aqueous phase. The feasibility of the use of luminescence spectroscopy as a technique to understand the complexation of trivalent f-elements cations viz. Eu(III) and Tb(III) with acetohydroxamic acid (AHA) in nitric acid medium has been examined. The luminescence lifetimes for the 1 × 10-3 M Eu(III) and AHA complex system decreased with increased AHA concentration from 116 ± 0.2 μs (no AHA) to 1.6 ± 0.1 μs (0.1 M AHA) which was attributed to dynamic quenching. The corrected fluorescence intensities were used to calculate the stability constant (log K) for the formation of 1:1 Eu3+-AHA complex as 1.42 ± 0.64 under the conditions of this study. By contrast, the Tb(III)-AHA system at pH 3 (HNO3) did not show any significant variation in the life times of the excited state (364 ± 9 μs) suggesting the absence of dynamic quenching. The spectral changes in Tb(III)-AHA system showed the formation of 1:1 complex (log K: 1.72 ± 0.21). These studies suggest that the extent of AHA complexation with the rare earth elements will be insignificant as compared to tetravalent metal ions Pu(IV) and Np(IV) under UREX process conditions.

  7. Investigations into the synthesis and fluorescence properties of Eu(III), Tb(III), Sm(III) and Gd(III) complexes of a novel bis-beta-diketone-type ligand.

    PubMed

    Luo, Yi-Ming; Chen, Zhe; Tang, Rui-Ren; Xiao, Lin-Xiang; Peng, Hong-Jian

    2008-02-01

    A novel bis-beta-diketon ligand, 1,1'-(2,6-bispyridyl)bis-3-phenyl-1,3-propane-dione (L), was designed and synthesized and its complexes with Eu(III), Tb(III), Sm(III) and Gd(III) ions were successfully prepared. The ligand and the corresponding metal complexes were characterized by elemental analysis, and infrared, mass and proton nuclear magnetic resonance spectroscopy. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring. The fluorescence properties of these complexes in solid state were investigated and it was discovered that all of the lanthanide ions could be sensitized by the ligand (L) to some extent. In particular, the Tb(III) complex was an excellent green-emitter and would be a potential candidate material for applications in organic light-emitting devices (OLEDs) and medical diagnosis.

  8. Investigations into the synthesis and fluorescence properties of Eu(III), Tb(III), Sm(III) and Gd(III) complexes of a novel bis- β-diketone-type ligand

    NASA Astrophysics Data System (ADS)

    Luo, Yi-Ming; Chen, Zhe; Tang, Rui-Ren; Xiao, Lin-Xiang; Peng, Hong-Jian

    2008-02-01

    A novel bis- β-diketon ligand, 1,1'-(2,6-bispyridyl)bis-3-phenyl-1,3-propane-dione (L), was designed and synthesized and its complexes with Eu(III), Tb(III), Sm(III) and Gd(III) ions were successfully prepared. The ligand and the corresponding metal complexes were characterized by elemental analysis, and infrared, mass and proton nuclear magnetic resonance spectroscopy. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring. The fluorescence properties of these complexes in solid state were investigated and it was discovered that all of the lanthanide ions could be sensitized by the ligand (L) to some extent. In particular, the Tb(III) complex was an excellent green-emitter and would be a potential candidate material for applications in organic light-emitting devices (OLEDs) and medical diagnosis.

  9. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    PubMed Central

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-01-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1–40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1–40 peptide on the basis of their emission response. PMID:26419607

  10. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    NASA Astrophysics Data System (ADS)

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  11. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes.

    PubMed

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-30

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  12. Pre-Botzinger Complex: A Brainstem Region That May Generate Respiratory Rhythm in Mammals

    NASA Astrophysics Data System (ADS)

    Smith, Jeffrey C.; Ellenberger, Howard H.; Ballanyi, Klaus; Richter, Diethelm W.; Feldman, Jack L.

    1991-11-01

    The location of neurons generating the rhythm of breathing in mammals is unknown. By microsection of the neonatal rat brainstem in vitro, a limited region of the ventral medulla (the pre-Botzinger Complex) that contains neurons essential for rhythmogenesis was identified. Rhythm generation was eliminated by removal of only this region. Medullary slices containing the pre-Botzinger Complex generated respiratory-related oscillations similar to those generated by the whole brainstem in vitro, and neurons with voltage-dependent pacemaker-like properties were identified in this region. Thus, the respiratory rhythm in the mammalian neonatal nervous system may result from a population of conditional bursting pacemaker neurons in the pre-Botzinger Complex.

  13. Application of Protocols Devised to Study Bi(III) Complex Formation by Voltammetry: The Bi(III)-Picolinic Acid System.

    PubMed

    Billing, Caren; Cukrowski, Ignacy

    2016-12-22

    Bi(III) coordination chemistry has been largely neglected due to the difficulties faced when studying these systems even though Bi(III) is used in various medicinal applications. This study of the Bi(III)-picolinic acid system by voltammetry applies the rigorous methodologies already developed to enable the study of Bi(III) systems starting in very acidic solutions to prevent precipitation. This includes calibrating the glass electrode accurately at these low pHs, compensating for the diffusion junction potential below pH 2 and determining the reduction potential of uncomplexed Bi(III) which cannot be directly measured. The importance of including nitrate from the background electrolyte as a competing species is highlighted, especially for data acquired below pH ∼ 2. From analysis of the voltammetric data, it was not clear whether a ML3OH species formed in solution or whether it was a combination of ML4 and ML4OH. Information from crystal structures and electrospray ionization-mass spectrometry measurements was thus used to propose the most probable species model. The log β values determined were 7.77 ± 0.07 for ML, 13.89 ± 0.07 for ML2, 18.61 ± 0.01 for ML3, 22.7 ± 0.2 for ML4, and 31.4 ± 0.2 for ML4OH. Application of these methodologies thus opens the door to broaden our understanding of Bi(III) complexation.

  14. Control of electron transport routes through redox-regulated redistribution of respiratory complexes

    PubMed Central

    Liu, Lu-Ning; Bryan, Samantha J.; Huang, Fang; Yu, Jianfeng; Nixon, Peter J.; Rich, Peter R.; Mullineaux, Conrad W.

    2012-01-01

    In cyanobacteria, respiratory electron transport takes place in close proximity to photosynthetic electron transport, because the complexes required for both processes are located within the thylakoid membranes. The balance of electron transport routes is crucial for cell physiology, yet the factors that control the predominance of particular pathways are poorly understood. Here we use a combination of tagging with green fluorescent protein and confocal fluorescence microscopy in live cells of the cyanobacterium Synechococcus elongatus PCC 7942 to investigate the distribution on submicron scales of two key respiratory electron donors, type-I NAD(P)H dehydrogenase (NDH-1) and succinate dehydrogenase (SDH). When cells are grown under low light, both complexes are concentrated in discrete patches in the thylakoid membranes, about 100–300 nm in diameter and containing tens to hundreds of complexes. Exposure to moderate light leads to redistribution of both NDH-1 and SDH such that they become evenly distributed within the thylakoid membranes. The effects of electron transport inhibitors indicate that redistribution of respiratory complexes is triggered by changes in the redox state of an electron carrier close to plastoquinone. Redistribution does not depend on de novo protein synthesis, and it is accompanied by a major increase in the probability that respiratory electrons are transferred to photosystem I rather than to a terminal oxidase. These results indicate that the distribution of complexes on the scale of 100–300 nm controls the partitioning of reducing power and that redistribution of electron transport complexes on these scales is a physiological mechanism to regulate the pathways of electron flow. PMID:22733774

  15. Water-soluble phthalocyanine complexes of Ga(III) and In(III) in the photodynamic inactivation of pathogenic fungus

    NASA Astrophysics Data System (ADS)

    Mantareva, V.; Angelov, I.; Wöhrle, D.; Dogandjiska, V.; Dimitrov, R.; Kussovski, V.

    2010-10-01

    Phthalocyanines of gallium(III) and indium(III) (GaPc1 and InPc1) bearing four methylpyridyloxy groups on the periphery of the phthalocyanine ring were synthesized. The both phthalocyanines were obtained with a good solubility in water solutions, which make them suitable for application in the Photodynamic therapy (PDT). The absorbance in the Uv-vis region of the complexes is typical for MPc with a highly intensive maximum in the far red spectra (681 nm - 697 nm for GaPc1 and for InPc1, both in DMSO). The fluorescence maxima are red shifted (691 nm/716 nm). The fluorescence quantum yields of the both complexes are lower than that for the unsubstituted MPcs with values of 0.25 for GaPc1 and much lower for InPc1 (0.012), which suggested a quenching from the substituents. The photochemical properties of singlet oxygen generation show quenching curves of "Furane" test with a 1O2 formation that increase significantly in the presence of the heavy atoms such as Ga(III) and especially In(III). Photodynamic efficacy against C. albicans in planktonic media was evaluated with a high photodynamic effect for GaPc1 at low concentrations (0.5 μM, - 3 μM) at mild irradiation parameters (30-60 J cm-2 and 50 mW cm-2). The inactivation of the fungus cells with InPc1 was insignificant even at strong treatment conditions (6.8 μM 60 J cm-2). The water-soluble phthalocyanine complexes of Ga(III) and In (III) were compared to the recently studied by us water-soluble Zn(II)-phthalocyanine, which was shown to have a high potential for photodynamic inactivation of variety pathogenic bacterial strains.

  16. Contribution of Bordetella bronchiseptica Type III secretion system to respiratory disease in swine

    USDA-ARS?s Scientific Manuscript database

    Background: The type III secretion system (TTSS) of gram negative bacteria allows injection of effector proteins directly into the cytosol of eukaryotic cells. Previous studies have demonstrated that the B. bronchiseptica TTSS plays a role in the persistent bacterial colonization of the trachea of m...

  17. Design of luminescent biotinylation reagents derived from cyclometalated iridium(III) and rhodium(III) bis(pyridylbenzaldehyde) complexes.

    PubMed

    Leung, Siu-Kit; Kwok, Karen Ying; Zhang, Kenneth Yin; Lo, Kenneth Kam-Wing

    2010-06-07

    A new class of luminescent biotinylation reagents derived from cyclometalated iridium(III) and rhodium(III) bis(pyridylbenzaldehyde) biotin complexes, [Ir(pba)(2)(bpy-C6-biotin)](PF(6)) (1), [Ir(pba)(2)(bpy-TEG-biotin)](PF(6)) (2), and [Rh(pba)(2)(bpy-C6-biotin)](PF(6)) (3), together with their biotin-free counterparts [Ir(pba)(2)(bpy-Et)](PF(6)) (4) and [Rh(pba)(2)(bpy-Et)](PF(6)) (5) [Hpba = 4-(2-pyridyl)benzaldehyde, bpy-C6-biotin = 4-[(6-biotinamido)hexylaminocarbonyl]-4'-methyl-2,2'-bipyridine, bpy-TEG-biotin = 4-[(13-biotinamido-4,7,10-trioxa)tridecylaminocarbonyl]-4'-methyl-2,2'-bipyridine, bpy-Et = 4-(ethylaminocarbonyl)-4'-methyl-2,2'-bipyridine], have been synthesized and characterized and their photophysical and electrochemical properties studied. Upon photoexcitation, the iridium(III) complexes 1, 2, and 4 exhibited intense and long-lived orange-yellow luminescence in fluid solutions at 298 K and in rigid glass at 77 K. The rhodium(III) complexes 3 and 5 were weakly emissive in fluid solutions at 298 K but showed intense luminescence in low-temperature glass. In view of the structured emission profiles and the long lifetimes, the emission of all of the complexes has been assigned to a triplet intraligand ((3)IL) (pi --> pi*) (pba) excited state, which was probably mixed with some triplet metal-to-ligand charge-transfer ((3)MLCT) [dpi(Ir or Rh) --> pi*(pba)] character. To investigate the reactivity of the aldehyde groups, complex 2 was reacted with n-butylamine, resulting in the formation of the complex [Ir(ppy-CH(2)NHC(4)H(9))(2)(bpy-TEG-biotin)](PF(6)) (2a) [Hppy-CH(2)NHC(4)H(9) = 2-[4-[N-(n-butyl)aminomethyl]phenyl]pyridine]. All of the aldehyde complexes have been used to biotinylate bovine serum albumin (BSA) to form bioconjugates 1-BSA-5-BSA. The bioconjugates have been isolated, purified, and characterized and their photophysical properties studied. Upon photoexcitation, all of the bioconjugates were luminescent and the emission has been

  18. Synthesis, characterization and fluorescence properties of Eu(III) and Tb(III) complexes with novel mono-substituted β-diketone ligands and 1,10-phenanthroline

    NASA Astrophysics Data System (ADS)

    Luo, Yi-Ming; Li, Jun; Xiao, Lin-Xiang; Tang, Rui-Ren; Tang, Xin-Cun

    2009-05-01

    Two novel pyridine-2,6-dicarboxylic acid derivatives of mono-β-diketone, methyl 6-benzoylacetyl-2-pyridinecarboxylate (MBAP) and 6-benzoylacetyl-2-pyridinecarboxylic acid (BAPA) and their Eu(III) and Tb(III) complexes were synthesized and characterized by elemental analysis, FT-IR, 1H NMR and TG-DTG. Moreover, their Eu(III) and Tb(III) complexes using 1,10-phenanthroline as a secondary ligand were prepared and characterized. The luminescence properties of these complexes in solid state were investigated in detail. The results suggested that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes, the fluorescence intensity of Ln(III) complexes with BAPA is about twice as strong as that of Ln(III) complexes with MBAP, the fluorescence of mono-β-diketone complexes using 1,10-phenanthroline as a secondary ligand was prominently higher than that of complexes without adding 1,10-phenanthroline, and the ligand BAPA is an excellent sensitizer to Eu(III) and Tb(III) ion.

  19. Synthesis, characterization and fluorescence properties of Eu(III) and Tb(III) complexes with novel mono-substituted beta-diketone ligands and 1,10-phenanthroline.

    PubMed

    Luo, Yi-Ming; Li, Jun; Xiao, Lin-Xiang; Tang, Rui-Ren; Tang, Xin-Cun

    2009-05-01

    Two novel pyridine-2,6-dicarboxylic acid derivatives of mono-beta-diketone, methyl 6-benzoylacetyl-2-pyridinecarboxylate (MBAP) and 6-benzoylacetyl-2-pyridinecarboxylic acid (BAPA) and their Eu(III) and Tb(III) complexes were synthesized and characterized by elemental analysis, FT-IR, (1)H NMR and TG-DTG. Moreover, their Eu(III) and Tb(III) complexes using 1,10-phenanthroline as a secondary ligand were prepared and characterized. The luminescence properties of these complexes in solid state were investigated in detail. The results suggested that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes, the fluorescence intensity of Ln(III) complexes with BAPA is about twice as strong as that of Ln(III) complexes with MBAP, the fluorescence of mono-beta-diketone complexes using 1,10-phenanthroline as a secondary ligand was prominently higher than that of complexes without adding 1,10-phenanthroline, and the ligand BAPA is an excellent sensitizer to Eu(III) and Tb(III) ion.

  20. A Comprehensive Genomic Analysis Reveals the Genetic Landscape of Mitochondrial Respiratory Chain Complex Deficiencies

    PubMed Central

    Nyuzuki, Hiromi; Moriyama, Yohsuke; Mizuno, Yosuke; Hirata, Tomoko; Yatsuka, Yukiko; Yamashita-Sugahara, Yzumi; Nakachi, Yutaka; Kato, Hidemasa; Okuda, Akihiko; Tamaru, Shunsuke; Borna, Nurun Nahar; Banshoya, Kengo; Aigaki, Toshiro; Sato-Miyata, Yukiko; Ohnuma, Kohei; Suzuki, Tsutomu; Nagao, Asuteka; Maehata, Hazuki; Matsuda, Fumihiko; Higasa, Koichiro; Nagasaki, Masao; Yasuda, Jun; Yamamoto, Masayuki; Fushimi, Takuya; Shimura, Masaru; Kaiho-Ichimoto, Keiko; Harashima, Hiroko; Yamazaki, Taro; Mori, Masato; Murayama, Kei; Ohtake, Akira; Okazaki, Yasushi

    2016-01-01

    Mitochondrial disorders have the highest incidence among congenital metabolic disorders characterized by biochemical respiratory chain complex deficiencies. It occurs at a rate of 1 in 5,000 births, and has phenotypic and genetic heterogeneity. Mutations in about 1,500 nuclear encoded mitochondrial proteins may cause mitochondrial dysfunction of energy production and mitochondrial disorders. More than 250 genes that cause mitochondrial disorders have been reported to date. However exact genetic diagnosis for patients still remained largely unknown. To reveal this heterogeneity, we performed comprehensive genomic analyses for 142 patients with childhood-onset mitochondrial respiratory chain complex deficiencies. The approach includes whole mtDNA and exome analyses using high-throughput sequencing, and chromosomal aberration analyses using high-density oligonucleotide arrays. We identified 37 novel mutations in known mitochondrial disease genes and 3 mitochondria-related genes (MRPS23, QRSL1, and PNPLA4) as novel causative genes. We also identified 2 genes known to cause monogenic diseases (MECP2 and TNNI3) and 3 chromosomal aberrations (6q24.3-q25.1, 17p12, and 22q11.21) as causes in this cohort. Our approaches enhance the ability to identify pathogenic gene mutations in patients with biochemically defined mitochondrial respiratory chain complex deficiencies in clinical settings. They also underscore clinical and genetic heterogeneity and will improve patient care of this complex disorder. PMID:26741492

  1. A Comprehensive Genomic Analysis Reveals the Genetic Landscape of Mitochondrial Respiratory Chain Complex Deficiencies.

    PubMed

    Kohda, Masakazu; Tokuzawa, Yoshimi; Kishita, Yoshihito; Nyuzuki, Hiromi; Moriyama, Yohsuke; Mizuno, Yosuke; Hirata, Tomoko; Yatsuka, Yukiko; Yamashita-Sugahara, Yzumi; Nakachi, Yutaka; Kato, Hidemasa; Okuda, Akihiko; Tamaru, Shunsuke; Borna, Nurun Nahar; Banshoya, Kengo; Aigaki, Toshiro; Sato-Miyata, Yukiko; Ohnuma, Kohei; Suzuki, Tsutomu; Nagao, Asuteka; Maehata, Hazuki; Matsuda, Fumihiko; Higasa, Koichiro; Nagasaki, Masao; Yasuda, Jun; Yamamoto, Masayuki; Fushimi, Takuya; Shimura, Masaru; Kaiho-Ichimoto, Keiko; Harashima, Hiroko; Yamazaki, Taro; Mori, Masato; Murayama, Kei; Ohtake, Akira; Okazaki, Yasushi

    2016-01-01

    Mitochondrial disorders have the highest incidence among congenital metabolic disorders characterized by biochemical respiratory chain complex deficiencies. It occurs at a rate of 1 in 5,000 births, and has phenotypic and genetic heterogeneity. Mutations in about 1,500 nuclear encoded mitochondrial proteins may cause mitochondrial dysfunction of energy production and mitochondrial disorders. More than 250 genes that cause mitochondrial disorders have been reported to date. However exact genetic diagnosis for patients still remained largely unknown. To reveal this heterogeneity, we performed comprehensive genomic analyses for 142 patients with childhood-onset mitochondrial respiratory chain complex deficiencies. The approach includes whole mtDNA and exome analyses using high-throughput sequencing, and chromosomal aberration analyses using high-density oligonucleotide arrays. We identified 37 novel mutations in known mitochondrial disease genes and 3 mitochondria-related genes (MRPS23, QRSL1, and PNPLA4) as novel causative genes. We also identified 2 genes known to cause monogenic diseases (MECP2 and TNNI3) and 3 chromosomal aberrations (6q24.3-q25.1, 17p12, and 22q11.21) as causes in this cohort. Our approaches enhance the ability to identify pathogenic gene mutations in patients with biochemically defined mitochondrial respiratory chain complex deficiencies in clinical settings. They also underscore clinical and genetic heterogeneity and will improve patient care of this complex disorder.

  2. Neodymium(III) Complexation by Amino-Carbohydrates via a Ligand-Controlled Hydrolysis Mechanism

    SciTech Connect

    Levitskaia, Tatiana G.; Chen, Yongsheng; Fulton, John L.; Sinkov, Sergey I.

    2011-07-28

    Chelation of neodymium-III Nd(III) by D-glucosamine (DGA) and chitosan was investigated in solution at near-physiological pH and ionic strength. This research demonstrates the first example of the lanthanide ion heteroleptic hydroxo-carbohydrate complex in solution. It was demonstrated that DGA and chitosan suppressed formation of polynuclear Nd(III) species at elevated pH.

  3. Intermediate States of Ribonuclease III in Complex with Double-Stranded RNA

    SciTech Connect

    Gan, Jianhua; Tropea, Joseph E.; Austin, Brian P.; Court, Donald L.; Waugh, David S.; Ji, Xinhua

    2010-07-19

    Bacterial ribonuclease III (RNase III) can affect RNA structure and gene expression in either of two ways: as a processing enzyme that cleaves double-stranded (ds) RNA, or as a binding protein that binds but does not cleave dsRNA. We previously proposed a model of the catalytic complex of RNase III with dsRNA based on three crystal structures, including the endonuclease domain of RNase III with and without bound metal ions and a dsRNA binding protein complexed with dsRNA. We also reported a noncatalytic assembly observed in the crystal structure of an RNase III mutant, which binds but does not cleave dsRNA, complexed with dsRNA. We hypothesize that the RNase III {center_dot} dsRNA complex can exist in two functional forms, a catalytic complex and a noncatalytic assembly, and that in between the two forms there may be intermediate states. Here, we present four crystal structures of RNase III complexed with dsRNA, representing possible intermediates.

  4. Assembly and Function of the RNA Editing Complex in Trypanosoma brucei Requires Band III Protein

    PubMed Central

    Huang, Catherine E.; O'Hearn, Sean F.; Sollner-Webb, Barbara

    2002-01-01

    Trypanosome RNA editing, the posttranscriptional insertion and deletion of U residues in mitochondrial transcripts, is catalyzed by a protein complex containing seven distinct proteins. In this study, we cloned the gene for band III, a 555-amino-acid protein with two separate zinc finger motifs. We prepared antibodies that showed band III protein cofractionates with the previously characterized band IV protein throughout the purification of the editing complex and is not found free or in other protein associations; therefore, it is a true constituent of the editing complex. Double-stranded RNA interference efficiently depleted band III protein and demonstrated that band III expression is essential for growth of procyclic trypanosomes and for RNA editing. These depleted cell extracts were deficient specifically in guide RNA-directed endonuclease cleavage at both U deletion and U insertion sites and in the activity of the band IV ligase, but they retained the 3′-U-exonuclease and terminal-U-transferase activities as well as band V ligase of the editing complex. Loss of band III protein also resulted in almost complete loss of the band IV ligase protein and altered sedimentation of the band V ligase. These data indicate that band III is either the RNA editing endonuclease or a factor critical for cleavage activity in the editing complex. They also demonstrate that band III is required for proper assembly of the editing complex. PMID:11940676

  5. Spectroscopic studies on the interaction of quercetin-terbium(III) complex with calf thymus DNA.

    PubMed

    Dehghan, Gholamreza; Dolatabadi, Jafar Ezzati Nazhad; Jouyban, Abolghasem; Zeynali, Karim Asadpour; Ahmadi, Seyed Mojtaba; Kashanian, Soheila

    2011-03-01

    The interaction of native calf thymus DNA (CT-DNA) with quercetin-terbium(III) [Q-Tb(III)] complex at physiological pH was monitored by UV absorption spectrophotometry, circular dichroism, fluorescence spectroscopy, and viscosimetric techniques. The complex displays binding properties to the CT-DNA and was found to interact with CT-DNA through outside binding, demonstrated by a hypochromic effect of Q-Tb(III) on the UV spectra of CT-DNA and the calculated association constants (K). Also, decrease in the specific viscosity of CT-DNA, decrease in the fluorescence intensity of Q-Tb(III) solutions in the presence of increasing amounts of CT-DNA, and detectable changes in the circular dichroism spectrum of CT-DNA are other evidences to indicate that Q-Tb(III) complex interact with CT-DNA through outside binding.

  6. Mitochondrial Ca2+ influx targets cardiolipin to disintegrate respiratory chain complex II for cell death induction

    PubMed Central

    Hwang, M-S; Schwall, C T; Pazarentzos, E; Datler, C; Alder, N N; Grimm, S

    2014-01-01

    Massive Ca2+ influx into mitochondria is critically involved in cell death induction but it is unknown how this activates the organelle for cell destruction. Using multiple approaches including subcellular fractionation, FRET in intact cells, and in vitro reconstitutions, we show that mitochondrial Ca2+ influx prompts complex II of the respiratory chain to disintegrate, thereby releasing an enzymatically competent sub-complex that generates excessive reactive oxygen species (ROS) for cell death induction. This Ca2+-dependent dissociation of complex II is also observed in model membrane systems, but not when cardiolipin is replaced with a lipid devoid of Ca2+ binding. Cardiolipin is known to associate with complex II and upon Ca2+ binding coalesces into separate homotypic clusters. When complex II is deprived of this lipid, it disintegrates for ROS formation and cell death. Our results reveal Ca2+ binding to cardiolipin for complex II disintegration as a pivotal step for oxidative stress and cell death induction. PMID:24948011

  7. Phosphorescent Neutral Iridium (III) Complexes for Organic Light-Emitting Diodes.

    PubMed

    Bin Mohd Yusoff, Abd Rashid; Huckaba, Aron J; Nazeeruddin, Mohammad Khaja

    2017-04-01

    The development of transition metal complexes for application in light-emitting devices is currently attracting significant research interest. Among phosphorescent emitters, those involving iridium (III) complexes have proven to be exceedingly useful due to their relatively short triplet lifetime and high phosphorescence quantum yields. The emission wavelength of iridium (III) complexes significantly depends on the ligands, and changing the electronic nature and the position of the ligand substituents can control the properties of the ligands. In this chapter, we discuss recent developments of phosphorescent transition metal complexes for organic light-emitting diode applications focusing solely on the development of iridium metal complexes.

  8. Cation transport by the respiratory NADH:quinone oxidoreductase (complex I): facts and hypotheses.

    PubMed

    Steffen, Wojtek; Steuber, Julia

    2013-10-01

    The respiratory complex I (electrogenic NADH:quinone oxidoreductase) has been considered to act exclusively as a H+ pump. This was questioned when the search for the NADH-driven respiratory Na+ pump in Klebsiella pneumoniae initiated by Peter Dimroth led to the discovery of a Na+-translocating complex in this enterobacterium. The 3D structures of complex I from different organisms support the idea that the mechanism of cation transport by complex I involves conformational changes of the membrane-bound NuoL, NuoM and NuoN subunits. In vitro methods to follow Na+ transport were compared with in vivo approaches to test whether complex I, or its individual NuoL, NuoM or NuoN subunits, extrude Na+ from the cytoplasm to the periplasm of bacterial host cells. The truncated NuoL subunit of the Escherichia coli complex I which comprises amino acids 1-369 exhibits Na+ transport activity in vitro. This observation, together with an analysis of putative cation channels in NuoL, suggests that there exists in NuoL at least one continuous pathway for cations lined by amino acid residues from transmembrane segments 3, 4, 5, 7 and 8. Finally, we discuss recent studies on Na+ transport by mitochondrial complex I with respect to its putative role in the cycling of Na+ ions across the inner mitochondrial membrane.

  9. Development of a C3-symmetric benzohydroxamate tripod: Trimetallic complexation with Fe(III), Cr(III) and Al(III)

    NASA Astrophysics Data System (ADS)

    Baral, Minati; Gupta, Amit; Kanungo, B. K.

    2016-06-01

    The design, synthesis and physicochemical characterization of a C3-symmetry Benzene-1,3,5-tricarbonylhydroxamate tripod, noted here as BTHA, are described. The chelator was built from a benzene as an anchor, symmetrically extended by three hydroxamate as ligating moieties, each bearing O, O donor sites. A combination of absorption spectrophotometry, potentiometry and theoretical investigations are used to explore the complexation behavior of the ligand with some trivalent metal ions: Fe(III), Cr(III), and Al(III). Three protonation constants were calculated for the ligand in a pH range of 2-11 in a highly aqueous medium (9:1 H2O: DMSO). A high rigidity in the molecular structure restricts the formation of 1:1 (M/L) metal encapsulation but shows a high binding efficiency for a 3:1 metal ligand stoichiometry giving formation constant (in β unit) 28.73, 26.13 and 19.69 for [M3L]; Mdbnd Fe(III), Al(III) and Cr(III) respectively, and may be considered as an efficient Fe-carrier. The spectrophotometric study reveals of interesting electronic transitions occurred during the complexation. BTHA exhibits a peak at 238 nm in acidic pH and with the increase of pH, a new peak appeared at 270 nm. A substantial shifting in both of the peaks in presence of the metal ions implicates a s coordination between ligand and metal ions. Moreover, complexation of BTHA with iron shows three distinct colors, violet, reddish orange and yellow in different pH, enables the ligand to be considered for the use as colorimetric sensor.

  10. Complexation of Curium(III) with DTPA at 10–70 °C: Comparison with Eu(III)–DTPA in Thermodynamics, Luminescence, and Coordination Modes

    SciTech Connect

    Tian, Guoxin; Zhang, Zhiyong; Martin, Leigh R.; Rao, Linfeng

    2015-02-16

    Separation of trivalent actinides (An(III)) from trivalent lanthanides (Ln(III)) is a challenging task because of their nearly identical chemical properties. Diethylenetriaminepentaacetate (DTPA), a key reagent used in the TALSPEAK process that effectively separates An(III) from Ln(III), is believed to play a critical role in the An(III)/Ln(III) separation. However, the underlying principles for the separation based on the difference in the complexation of DTPA with An(III) and Ln(III) remain unclear. In this work, the complexation of DTPA with Cm(III) at 10-70 ºC was investigated by spectrophotometry, luminescence spectroscopy, and microcalorimetry, in conjunction with computational methods. The binding strength, the enthalpy of complexation, the coordination modes, and the luminescence properties are compared between the Cm(III)-DTPA and Eu(III)-DTPA systems. The experimental and computational data have demonstrated that the difference between Cm(III) and Eu(III) in the binding strength with DTPA can be attributed to the stronger covalence bonding between Cm(III) and the nitrogen donors of DTPA.

  11. The Complexation of Mn(III) in the Sediments and Water Column of two Coastal Estuaries

    NASA Astrophysics Data System (ADS)

    Oldham, V.; Mucci, A.; Luther, G. W., III

    2015-12-01

    In seawater, we find that the complexation of the intermediate manganese oxidation state, dissolved Mn(III), is kinetically stabilized by organic ligands in diverse environments. The cycling of these complexes is also tightly coupled to the cycles of C, O, N, S, and Fe. In the suboxic porewaters of the St. Lawrence Estuary (2011 (1), 2014 (here)), Mn(III)-L complexes made up to 100 % of total dissolved Mn (dMn(T)). The porewaters were dominated by weak complexes in lower and upper estuary porewaters (35 ppt salinity), whereas in the Saguenay Fjord (30 ppt salinity), weak (logKcond=11.1-11.6) and strong (logKcond>13.6) Mn(III)-L complexes were found in the same sample, which were kinetically stable to reduction - even in the presence of excess soluble Fe(II). The site at the Saguenay fjord likely has more terrestrial influence, and potentially different Mn(III)-L binding ligands than in the more oceanic samples. Overlying waters at both sites indicate that dMn(T) is fluxing out of the sediments, and all water column samples contained strong Mn(III)-L complexes (up to 86% of dMn(T)). Laboratory tests show that strong terrestrial Mn(III)-L complexes can precipitate at pH<2, and so previous dMn(T) assays in such environments, involving an acidification step, may have omitted an important fraction of dMn(T). These findings present the first measurement of two Mn(III)-binding ligand classes in the same water mass, and indicate that Mn(III)-L complexes have diverse and varying reactivity. We will discuss the implication of fluxing Mn(III)-L complexes from sediments to the overlying water column, in the St. Lawrence system compared to our data from the Chesapeake Bay (2013 (2), 2014 (here)) where strong Mn(III)-L complexes made up to 50 % of total dissolved Mn (dMn(T)) in anoxic bottom waters, and were partially kinetically stable to sulfide reduction. 1. Madison, A.S., Tebo, B.M., Mucci, A., Sundby, B., Luther, G.W. 2013. Abundant porewater Mn(III) is a major component of

  12. Complexation Effect on Redox Potential of Iron(III)-Iron(II) Couple: A Simple Potentiometric Experiment

    ERIC Educational Resources Information Center

    Rizvi, Masood Ahmad; Syed, Raashid Maqsood; Khan, Badruddin

    2011-01-01

    A titration curve with multiple inflection points results when a mixture of two or more reducing agents with sufficiently different reduction potentials are titrated. In this experiment iron(II) complexes are combined into a mixture of reducing agents and are oxidized to the corresponding iron(III) complexes. As all of the complexes involve the…

  13. Thermodynamics of complexation in an aqueous solution of Tb(III) nitrate at 298 K

    NASA Astrophysics Data System (ADS)

    Lobacheva, O. L.; Berlinskii, I. V.; Dzhevaga, N. V.

    2017-01-01

    The pH of the formation of hydroxo complexes and hydrates in an aqueous solution of terbium Tb(III) is determined using combined means of potentiometric and conductometric titration. The stability constants of the hydroxo complexes, the products of hydroxide solubility, and the Gibbs energy of terbium hydroxo complex formation are calculated.

  14. Photo- and electroluminescence of mixed-ligand Eu(III) complexes

    NASA Astrophysics Data System (ADS)

    Eremina, N. S.; Meshkova, S. B.; Degtyarenko, K. M.; Kopylova, T. N.; Topilova, Z. M.; Gadirov, R. M.; Samsonova, L. G.

    2012-05-01

    Spectral and luminescent properties of mixed-ligand Eu(III) complexes were studied in solutions and in polyvinylcarbazole (PVC) thin films. Trends in their variations were found depending on the complex structure and excitation mode. The electroluminescence was observed in ITO/PEDOT/Eu complex:PVC/CaMg/Al devices. Their current-voltage and voltage-brightness characteristics were investigated.

  15. Complexation Effect on Redox Potential of Iron(III)-Iron(II) Couple: A Simple Potentiometric Experiment

    ERIC Educational Resources Information Center

    Rizvi, Masood Ahmad; Syed, Raashid Maqsood; Khan, Badruddin

    2011-01-01

    A titration curve with multiple inflection points results when a mixture of two or more reducing agents with sufficiently different reduction potentials are titrated. In this experiment iron(II) complexes are combined into a mixture of reducing agents and are oxidized to the corresponding iron(III) complexes. As all of the complexes involve the…

  16. Mitochondria-targeting phosphorescent iridium(III) complexes for living cell imaging.

    PubMed

    Zhang, Qingqing; Cao, Rui; Fei, Hao; Zhou, Ming

    2014-11-28

    Two phosphorescent iridium(III) complexes conjugated to a lipophilic triphenylphosphonium cation moiety, IrMitoOlivine and IrMitoNIR, were synthesized. The complexes show high mitochondria-specificity and relatively lower cytotoxicity. Time-lapse confocal imaging indicates that both complexes exhibit an excellent anti-photobleaching capability under continuous laser irradiation.

  17. Site-selective recognition of peptide phosphorylation by a terbium(III) complex in aqueous solution.

    PubMed

    Wang, Xiaohui; Yang, Tao; Luo, Jian; Yang, Liu; Yao, Cheng

    2015-05-11

    A terbium(III) complex exhibits efficient selectivity for proximal diphosphorylation of peptides, accompanied with remarkable luminescence enhancement in the presence of Zn(II) ions in both buffer and protein extraction solutions from brain homogenates of mice.

  18. Synthesis and luminescence properties of iridium(III) azide- and triazole-bisterpyridine complexes.

    PubMed

    Goldstein, Daniel C; Peterson, Joshua R; Cheng, Yuen Yap; Clady, Raphael G C; Schmidt, Timothy W; Thordarson, Pall

    2013-07-26

    We describe here the synthesis of azide-functionalised iridium(III) bisterpyridines using the "chemistry on the complex" strategy. The resulting azide-complexes are then used in the copper(I)-catalysed azide-alkyne Huisgen 1,3-dipolar cycloaddition "click chemistry" reaction to from the corresponding triazole-functionalised iridium(III) bisterpyridines. The photophysical characteristics, including lifetimes, of these compounds were also investigated. Interestingly, oxygen appears to have very little effect on the lifetime of these complexes in aqueous solutions. Unexpectedly, sodium ascorbate acid appears to quench the luminescence of triazole-functionalised iridium(III) bisterpyridines, but this effect can be reversed by the addition of copper(II) sulfate, which is known to oxidize ascorbate under aerobic conditions. The results demonstrate that iridium(III) bisterpyridines can be functionalized for use in "click chemistry" facilitating the use of these photophysically interesting complexes in the modification of polymers or surfaces, to highlight just two possible applications.

  19. Reactivity of a Cobalt(III)–Hydroperoxo Complex in Electrophilic Reactions

    DOE PAGES

    Shin, Bongki; Sutherlin, Kyle D.; Ohta, Takehiro; ...

    2016-11-15

    The reactivity of mononuclear metal-hydroperoxo adducts has fascinated researchers in many areas due to their diverse biological and catalytic processes. In this study, a mononuclear cobalt(III)-peroxo complex bearing a tetradentate macrocyclic ligand, [CoIII(Me3-TPADP)(O2)]+ (Me3-TPADP = 3,6,9-trimethyl-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane), was prepared by reacting [CoII(Me3-TPADP)(CH3CN)2]2+ with H2O2 in the presence of triethylamine. Upon protonation, the cobalt(III)- peroxo intermediate was converted into a cobalt(III)-hydroperoxo complex, [CoIII(Me3-TPADP)(O2H)(CH3CN)]2+. The mononuclear cobalt(III)-peroxo and -hydroperoxo intermediates were characterized by a variety of physicochemical methods. Results of electrospray ionization mass spectrometry clearly show the transformation of the intermediates: the peak at m/z 339.2 assignable to the cobalt(III)-peroxo species disappears withmore » concomitant growth of the peak at m/z 190.7 corresponding to the cobalt(III)-hydroperoxo complex (with bound CH3CN). Isotope labeling experiments further support the existence of the cobalt(III)-peroxo and -hydroperoxo complexes. In particular, the O-O bond stretching frequency of the cobalt(III)-hydroperoxo complex was determined to be 851 cm-1 for 16O2H samples (803 cm-1 for 18O2H samples) and its Co-O vibrational energy was observed at 571 cm-1 for 16O2H samples (551 cm-1 for 18O2H samples; 568 cm-1 for 16O2 2H samples) by resonance Raman spectroscopy. Reactivity studies performed with the cobalt(III)-peroxo and -hydroperoxo complexes in organic functionalizations reveal that the latter is capable of conducting oxygen atom transfer with an electrophilic character, whereas the former exhibits no oxygen atom transfer reactivity under the same reaction conditions. Alternatively, the cobalt(III)-hydroperoxo complex does not perform hydrogen atom transfer reactions, while analogous low-spin Fe(III)-hydroperoxo complexes are capable of this reactivity. Density function

  20. [Clinical and bacteriological effects of cefetamet pivoxil against community-acquired respiratory tract infections. Part III].

    PubMed

    Ishihara, R; Suzuki, Y; Nishinari, C; Ishii, Y; Matsumoto, Y; Kaku, M; Shimada, J

    1999-06-01

    We investigated clinical and bacteriological effects of cefetamet pivoxil (CEMT-PI) on community-acquired respiratory tract infection and obtained the following results: This method of investigation was almost the same to those adopted in 1994 and 1996. 1. 512 cases of respiratory tract infection were treated with CEMT-PI under the same protocol at a total of 53 institutions in Tokyo, Kanagawa, Saitama, Chiba and Yamanashi prefectures from January, 1, 1998 over March, 31, 1998. Outpatients accounted for 99.7% of all subjects. Diagnoses given to these patients included pharyngolaryngitis (51.4%), tonsillitis (37.7%), and acute bronchitis (10.1%). 2. For the bacteriological study, a manual detailing the method of collecting specimens, storage and transport was distributed to the above-mentioned institutions. The isolation and identification of suspected causative bacteria, determination of minimum inhibitory concentrations (MICs), and investigation of beta-lactamase production were conducted all together at Section of Studies, Tokyo Clinical Research Center. Suspected causative bacteria were detected in 144 (37.2%) out of 387 cases that were the analytical subjects of the clinical efficacy. The major bacteria identified were 32 strains of Streptococcus pyogenes and 19 strains of Haemophilus influenzae. The clinical efficacy (the ratio of improvement) of CEMT by suspected causative bacterium was 84.4% against CEMT-indicated organisms and 81.2% against CEMT-non-indicated organisms. 3. We investigated clinical efficacy rates (the ratio of "markedly improved" + "improved") by disease. The improvement rate was 78.4% in pharyngolaryngitis, 87.0% in tonsillitis, and 79.5% in acute bronchitis. The clinical efficacy rate was an average of 81.9% in all CEMT-PI indicated diseases.

  1. Identification of an iridium(III) complex with anti-bacterial and anti-cancer activity.

    PubMed

    Lu, Lihua; Liu, Li-juan; Chao, Wei-chieh; Zhong, Hai-Jing; Wang, Modi; Chen, Xiu-Ping; Lu, Jin-Jian; Li, Ruei-nian; Ma, Dik-Lung; Leung, Chung-Hang

    2015-09-29

    Group 9 transition metal complexes have been widely explored as therapeutic agents due to their unique geometry, their propensity to undergo ligand exchanges with biomolecules and their diverse steric and electronic properties. These metal complexes can offer distinct modes of action in living organisms compared to carbon-based molecules. In this study, we investigated the antimicrobial and anti-proliferative abilities of a series of cyclometallated iridium(III) complexes. The iridium(III) complex 1 inhibited the growth of S. aureus with MIC and MBC values of 3.60 and 7.19 μM, respectively, indicating its potent bactericidal activity. Moreover, complex 1 also exhibited cytotoxicity against a number of cancer cell lines, with particular potency against ovarian, cervical and melanoma cells. This cyclometallated iridium(III) complex is the first example of a substitutionally-inert, Group 9 organometallic compound utilized as a direct and selective inhibitor of S. aureus.

  2. Identification of an iridium(III) complex with anti-bacterial and anti-cancer activity

    PubMed Central

    Lu, Lihua; Liu, Li-Juan; Chao, Wei-chieh; Zhong, Hai-Jing; Wang, Modi; Chen, Xiu-Ping; Lu, Jin-Jian; Li, Ruei-nian; Ma, Dik-Lung; Leung, Chung-Hang

    2015-01-01

    Group 9 transition metal complexes have been widely explored as therapeutic agents due to their unique geometry, their propensity to undergo ligand exchanges with biomolecules and their diverse steric and electronic properties. These metal complexes can offer distinct modes of action in living organisms compared to carbon-based molecules. In this study, we investigated the antimicrobial and anti-proliferative abilities of a series of cyclometallated iridium(III) complexes. The iridium(III) complex 1 inhibited the growth of S. aureus with MIC and MBC values of 3.60 and 7.19 μM, respectively, indicating its potent bactericidal activity. Moreover, complex 1 also exhibited cytotoxicity against a number of cancer cell lines, with particular potency against ovarian, cervical and melanoma cells. This cyclometallated iridium(III) complex is the first example of a substitutionally-inert, Group 9 organometallic compound utilized as a direct and selective inhibitor of S. aureus. PMID:26416333

  3. Infrared spectra of new Re(III) complexes with thiourea derivatives.

    PubMed

    Gambino, Dinorah; Kremer, Eduardo; Baran, Enrique J

    2002-12-01

    Complexes of the type [Re(III)L6]X3, with L = thiourea, N-methylthiourea, N-ethylthiourea or N,N'-dimethytlthiourea and X = Cl- or PF6-, were prepared as suitable precursors for the synthesis of new rhenium complexes potentially useful in nuclear medicine. The infrared (IR) spectra of these complexes were recorded and analyzed and a general vibrational pattern for Re(III) complexes with thiourea derivatives could be established. Approximate assignments for N-allylthiourea and N-ethylthiourea are also proposed for the first time. The synthesis of the new complex [Re(III)(N-allylthiourea)6](PF6)3 is also reported, and information about its structural characteristics was obtained comparing its IR spectrum with those of the other complexes of the investigated series.

  4. Porcine respiratory disease complex: Interaction of vaccination and porcine circovirus type 2, porcine reproductive and respiratory syndrome virus, and Mycoplasma hyopneumoniae.

    PubMed

    Chae, Chanhee

    2016-06-01

    Porcine respiratory disease is a multifactorial and complex disease caused by a combination of infectious pathogens, environmental stressors, differences in production systems, and various management practices; hence the name porcine respiratory disease complex (PRDC) is used. Porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), and Mycoplasma hyopneumoniae are considered to be the most important pathogens that cause PRDC. Although interactions among the three major respiratory pathogens are well documented, it is also necessary to understand the interaction between vaccines and the three major respiratory pathogens. PRRSV and M. hyopneumoniae are well known to potentiate PCV2-associated lesions; however, PRRSV and mycoplasmal vaccines can both enhance PCV2 viraemia regardless of the effects of the actual PRRSV or M. hyopneumoniae infection. On the other hand, M. hyopneumoniae potentiates the severity of pneumonia induced by PRRSV, and vaccination against M. hyopneumoniae alone is also able to decrease PRRSV viraemia and PRRSV-induced lung lesions in dually infected pigs. This review focuses on (1) interactions between PCV2, PRRSV, and M. hyopneumoniae; and (2) interactions between vaccines and the three major respiratory pathogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Allosteric nucleotide-binding site in the mitochondrial NADH:ubiquinone oxidoreductase (respiratory complex I)

    PubMed Central

    Grivennikova, Vera G.; Gladyshev, Grigory V.; Vinogradov, Andrei D.

    2011-01-01

    The rotenone-insensitive NADH:hexaammineruthenium III (HAR) oxidoreductase reactions catalyzed by bovine heart and Yarrowia lipolytica submitochondrial particles or purified bovine complex I are stimulated by ATP and other purine nucleotides. The soluble fraction of mammalian complex I (FP) and prokaryotic complex I homolog NDH-1 in Paracoccus denitrificans plasma membrane lack stimulation of their activities by ATP. The stimulation appears as a decrease in apparent Km values for NADH and HAR. Thus, the “accessory” subunits of eukaryotic complex I bear an allosteric ATP-binding site. PMID:21624365

  6. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  7. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  8. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  9. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  10. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Chromium (Cr III) complex of N-ethyl-N... Substances for Use Only as Components of Paper and Paperboard § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N-ethyl -...

  11. Mechanistic aspects of the chemistry of mononuclear Cr(III) complexes with pendant-arm macrocyclic ligands and formation of discrete Cr(III)/Fe(II) and Cr(III)/Fe(II)/Co(III) cyano-bridged mixed valence compounds.

    PubMed

    Basallote, Manuel G; Bernhardt, Paul V; Calvet, Teresa; Castillo, Carmen E; Font-Bardia, Mercè; Martínez, Manuel; Rodríguez, Carlos

    2009-11-21

    The kinetics and mechanism of the redox reaction between [Fe(II)(CN)(6)](4-) and the macrocyclic ligand complex [CrClL(15)](2+) (L(15) = 6-methyl-1,4,8,12-tetraazacyclopentadecane-6-amine) has been studied at different pH values. In acidic solution, the expected redox process occurs with no formation of any of the possible Cr(III)/Fe(II) mixed valence complexes, as those seen for the Co(III) species of the same family, due to the enhanced lability of the Cr(II) species formed on Fe(II) to Fe(III) oxidation. In alkaline conditions, the formation of the complex [Cr(L(15))(OH)(2)](+) takes place as an initial step that precedes a simple substitution process producing the expected cyano-bridged Cr(III)/Fe(II) complex. In this species the potentially pentadentate ligand, L(15), has a tetradentate coordination mode with a protonated exocyclic primary amine group and the redox potential is shifted to more negative values, thus disfavouring a redox driven reaction; the equivalent complex [CrCl(HL(14))(H(2)O)](3+) (L(14) = 6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine) has been prepared by the same method and characterized by X-ray crystallography. The final [Fe(II)(CN)(6)](4-) substituted complex, [{(HL(15))(OH)Cr(III)NC}Fe(II)(CN)(5)](-) shows pK(a) values of 3.8 and 7.4, as expected for the aqua and amino ligands, respectively. Its characterization indicated its Class II mixed valence character with a very intense MMCT band at 350 nm showing a much larger extinction coefficient than that observed for the Co(III) complexes of the same family. This fact is in good agreement with the much larger Cr(III)-Fe(II) (t(2g)-t(2g)) coupling through cyanide bridging ligands expected for these complexes. The fully mixed metal/valence/ligand trimetallic complex [{(HL(15))(OH)Cr(III)NC}{L(13)Co(III)NC}Fe(II)(CN)(4)](2+) has been prepared following the same procedures and the results are comparable. The final complex has the same Class II mixed valence character and its electronic

  12. Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior.

    PubMed

    Chandrasekhar, Vadapalli; Hossain, Sakiat; Das, Sourav; Biswas, Sourav; Sutter, Jean-Pascal

    2013-06-03

    The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.

  13. Copper-Mediated Fluorination of Arylboronate Esters. Identification of a Copper(III) Fluoride Complex

    PubMed Central

    Fier, Patrick S.; Luo, Jingwei; Hartwig, John F.

    2013-01-01

    A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through aryl-boronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III) followed by rate-limiting transmetallation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS. PMID:23384209

  14. Copper-mediated fluorination of arylboronate esters. Identification of a copper(III) fluoride complex.

    PubMed

    Fier, Patrick S; Luo, Jingwei; Hartwig, John F

    2013-02-20

    A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through arylboronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III), followed by rate-limiting transmetalation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS.

  15. Investigation of complexes tannic acid and myricetin with Fe(III)

    NASA Astrophysics Data System (ADS)

    Sungur, Şana; Uzar, Atike

    2008-01-01

    The pH dependence of the complexes was determined by both potentiometric and spectrophotometric studies. Stability constants and stoichiometries of the formed complexes were determined using slope ratio method. Fe(III) was formed complexes with tannic acid of various stoichiometries, which in the 1:1 molar ratio at pH < 3, in the 2:1 molar ratio at pH 3-7 and in the 4:1 molar ratio at pH > 7. Fe(III) was formed complexes with myricetin in the 1:2 molar ratio at pH 4 and 5 and in the 1:1 molar ratio at pH 6. Stability constant values were found to be 10 5 to 10 17 and 10 5 to 10 9 for Fe(III)-tannic acid complexes and Fe(III)-myricetin complexes. Both tannic acid and myricetin were possessed minimum affinities to Cu(II) and Zn(II). They had less affinity for Al(III) than for Fe(III).

  16. Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity

    NASA Astrophysics Data System (ADS)

    Keskioğlu, Eren; Gündüzalp, Ayla Balaban; Çete, Servet; Hamurcu, Fatma; Erk, Birgül

    2008-08-01

    A series of metal complexes were synthesized from equimolar amounts of Schiff bases: 1,4-bis[3-(2-hydroxy-1-naphthaldimine)propyl]piperazine (bappnaf) and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)- p-menthane (damnaf) with metal chlorides. All of synthesized compounds were characterized by elemental analyses, spectral (UV-vis, IR, 1H- 13C NMR, LC-MS) and thermal (TGA-DTA) methods, magnetic and conductance measurements. Schiff base complexes supposed in tetragonal geometry have the general formula [M(bappnaf or damnaf)]Cl· nH 2O, where M = Cr(III), Co(III) and n = 2, 3. But also Fe(III) complexes have octahedral geometry by the coordination of two water molecules and the formula is [Fe(bappnaf or damnaf)(H 2O) 2]Cl. The changes in the selected vibration bands in FT-IR indicate that Schiff bases behave as (ONNO) tetradentate ligands and coordinate to metal ions from two phenolic oxygen atoms and two azomethine nitrogen atoms. Conductance measurements suggest 1:1 electrolytic nature of the metal complexes. The synthesized compounds except bappnaf ligand have the antimicrobial activity against the bacteria: Escherichia coli (ATCC 11230), Yersinia enterocolitica (ATCC 1501), Bacillus magaterium (RSKK 5117), Bacillus subtilis (RSKK 244), Bacillus cereus (RSKK 863) and the fungi: Candida albicans (ATCC 10239). These results have been considerably interest in piperazine derivatives due to their significant applications in antimicrobial studies.

  17. mer-[Fe III(bpca)(CN)3]-: a new low-spin iron(III) complex to build heterometallic ladder-like chains.

    PubMed

    Lescouëzec, Rodrigue; Vaissermann, Jacqueline; Toma, Luminita Marilena; Carrasco, Rosa; Lloret, Francesc; Julve, Miguel

    2004-04-05

    The novel mononuclear complex PPh(4)-mer-[Fe(III)(bpca)(3)(CN)(3)].H(2)O (1) [PPh(4)(+) = tetraphenylphosphonium cation and bpca = bis(2-pyridylcarbonyl)amidate anion] and ladder-like chain compound [[Fe(III)(bpca)(micro-CN)(3)Mn(II)(H(2)O)(3)] [Fe(III)(bpca)(CN)(3)

  18. Novel Luminescent Probe Based on a Terbium(III) Complex for Hemoglobin Determination

    NASA Astrophysics Data System (ADS)

    Yegorova, A. V.; Leonenko, I. I.; Aleksandrova, D. I.; Scrypynets, Yu. V.; Antonovich, V. P.; Ukrainets, I. V.

    2014-09-01

    We have studied the spectral luminescent properties of Tb(III) and Eu(III) complexes with a number of novel derivatives of oxoquinoline-3-carboxylic acid amides (L1-L5 ). We have observed quenching of the luminescence of 1:1 Tb(III)-L1-5 complexes by hemoglobin (Hb), which is explained by resonance energy transfer of electronic excitation from the donor (Tb(III)-L1-5 ) to the acceptor (Hb). Using the novel luminescent probe Tb(III)-L1, we have developed a method for determining Hb in human blood. The calibration Stern-Volmer plot is linear in the Hb concentration range 0.6-36.0 μg/mL, detection limit 0.2 μg/mL (3·10-9 mol/L).

  19. Selective DNA purine base photooxidation by bis-terdentate iridium(III) polypyridyl and cyclometalated complexes.

    PubMed

    Jacques, Alexandre; Kirsch-De Mesmaeker, Andrée; Elias, Benjamin

    2014-02-03

    Two bis-terdentate iridium(III) complexes with polypyridyl and cyclometalated ligands have been prepared and characterized. Their spectroscopic and electrochemical properties have been studied, and a photophysical scheme addressing their properties is proposed. Different types of excited states have been considered to account for the deactivation processes in each complex. Interestingly, in the presence of mono- or polynucleotides, a photoinduced electron-transfer process from a DNA purine base (i.e., guanine or adenine) to the excited complex is shown through luminescence quenching experiments. For the first time, this work reports evidence for selective DNA purine bases oxidation by excited iridium(III) bis-terdentate complexes.

  20. Enantiomeric NMR signal separation behavior and mechanism of samarium(III) and neodymium(III) complexes with (S,S)-ethylenediamine-N,N'-disuccinate.

    PubMed

    Aizawa, Sen-Ichi; Okano, Masaru; Kidani, Takahiro

    2017-04-12

    Enantiomeric (1) H and (13) C NMR signal separation behaviors of various α-amino acids and DL-tartarate were investigated by using the samarium(III) and neodymium(III) complexes with (S,S)-ethylenediamine-N,N'-disuccinate as chiral shift reagents. A relatively smaller concentration ratio of the lanthanide(III) complex to substrates was suitable for the neodymium(III) complex compared with the samarium(III) one, striking a balance between relatively greater signal separation and broadening. To clarify the difference in the signal separation behavior, the chemical shifts of β-protons for fully bound D- and L-alanine (δb (D) and δb (L)) and their adduct formation constants (Ks) were obtained for both metal complexes. Preference for D-alanine was similarly observed for both complexes, while it was revealed that the difference between the δb (D) and δb (L) values is the significant factor to determine the enantiomeric signal separation. The neodymium(III) and samarium(III) complexes can be used complementarily for higher and smaller concentration ranges of substrates, respectively, because the neodymium(III) complex gives the larger difference between the δb (D) and δb (L) values with greater signal broadening compared to the samarium(III) complex.

  1. Synthesis, spectroscopic characterization and antibacterial studies of lanthanide(III) Schiff base complexes containing N, O donor atoms

    NASA Astrophysics Data System (ADS)

    Lekha, L.; Raja, K. Kanmani; Rajagopal, G.; Easwaramoorthy, D.

    2014-01-01

    A series of six Ln(III) Schiff base complexes, Pr(III), Sm(III), Gd(III), Tb(III), Er(III) and Yb(III), were synthesized using sodium salt of Schiff base, 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-3-hydroxy-propionic acid, derived from L-serine and 5-bromosalicylaldehyde. These complexes having general formula [Ln(L)(NO3)2(H2O)]·NO3 were characterized by elemental analysis, conductivity measurements, UV-Vis, FT-IR, mass spectrometry and fluorescence studies. Elemental analysis and conductivity measurements suggest the complexes have a 1:1 stoichiometry. From the spectral studies it has been concluded that Ln(III) complexes display eight coordination. The Schiff base and its Ln(III) metal complexes have also been screened for their antibacterial activities by Agar diffusion method.

  2. Lanthanide(III) complexes of some natural siderophores: a thermodynamic, kinetic and relaxometric study.

    PubMed

    Tircsó, Gyula; Garda, Zoltán; Kálmán, Ferenc K; Baranyai, Zsolt; Pócsi, István; Balla, György; Tóth, Imre

    2013-10-01

    Stability constants of the complexes formed between the natural trihydroxamic acids desferrioxamine B (DFB) and desferricoprogen (DFC) with Nd(III), Gd(III) and Yb(III) ions were determined using pH-potentiometry. The equilibrium in these systems can be described by models containing mononuclear protonated (Ln(HL), Ln(H2L) and Ln(H3L)), deprotonated (LnL) and ternary hydroxo Ln(H-1L) complexes, but for both ligands dinuclear complexes of low stability were also detected. The stability constants for the Ln(HDFB)(+) complexes are 11.95 (Nd(III)), 13.16 (Gd(III)) and 14.67 (Yb(III)), while these values of the Ln(DFC) complexes are considerably higher (14.42 (Nd(III)), 15.14 (Gd(III)) and 16.49 (Yb(III))). The stability constants of the complexes of DFB and DFC are much lower than those of the Ln(L)3 complexes formed with some aromatic hydroxamic acids indicating that the relatively long spacer between the hydroxamic acid moieties in DFB and DFC is unfavorable for Ln(III) complexation. The relaxometric study conducted for the Gd(HDFB)(+) species revealed an interesting pH dependence of the relaxivity associated with a large hydration number (bishydrated complex) and fast water exchange (kex=(29.9±0.4)×10(6)s(-1)), which would be favorable for CA use. However the dissociation of Gd(HDFB)(+) is fairly fast (<2ms) under all conditions employed in the present work thus the kinetically labile Gd(HDFB)(+) is not suitable for in vivo CA applications. Some low stability ternary complexes were also detected with K(Gd(HDFB)(HCO3))=17.5±1.9 and K(Gd(HDFB)(Lactate))=8.4±3.2 but in the presence of citrate and phosphate ions the Gd(HDFB)(+) complex was found to dissociate.

  3. Solvation structure and thermodynamics for Pr(III), Nd(III) and Dy(III) complexes in ionic liquids evaluated by Raman spectroscopy and DFT calculation

    NASA Astrophysics Data System (ADS)

    Kuribara, Keita; Matsumiya, Masahiko; Tsunashima, Katsuhiko

    2016-12-01

    The coordination states of trivalent praseodymium, neodymium, and dysprosium complexes in the ionic liquid, triethyl-n-pentylphosphonium bis(trifluoromethyl-sulfonyl) amide ([P2225][TFSA]) were investigated by Raman spectroscopy. The effect of the concentration of rare earth ions on the Raman spectra was investigated, ranging from 0.23 to 0.45 mol kg-1 of Pr(III), Nd(III), and Dy(III) in [P2225][TFSA]. Based on a conventional analysis, the solvation numbers, n, of Pr(III), Nd(III), and Dy(III) in [P2225][TFSA] were determined to be 4.99, 5.01, and 5.00 at 298 K and 5.04, 5.06, and 5.07 at 373 K, respectively. Thermodynamic properties such as ΔisoG, ΔisoH, and ΔisoS for the isomerism of [TFSA]- from trans- to cis-coordinated isomer in the bulk and the first solvation sphere of the central RE3+ (RE = Pr, Nd, and Dy) cation in [P2225][TFSA] were evaluated from the temperature dependence of the Raman bands, measured at temperatures ranging from 298 to 398 K. Regarding the bulk properties, ΔisoG(bulk), ΔisoH(bulk), and TΔisoS(bulk) at 298 K were found to be -1.06, 6.86, and 7.92 kJ mol-1, respectively. The trans-[TFSA]- was a dominant contributor to the enthalpy, as shown by the positive value of ΔisoH(bulk). The value of TΔisoS(bulk) was slightly larger than that of ΔisoH(bulk), and cis-[TFSA]- was, therefore, entropy-controlled in [P2225][TFSA]. In contrast, in the first solvation sphere of the RE3+ cation, ΔisoH(RE) became remarkably negative, suggesting that cis-[TFSA]- isomers were stabilized by enthalpic contributions. Furthermore, ΔisoH(RE) contributed to the remarkable decrease in ΔisoG(RE), and this result clearly indicates that cis-[TFSA]- conformers bound to RE3+ cations are the preferred coordination state of [RE(III)(cis-TFSA)5]2- in [P2225][TFSA]. Moreover, optimized geometries and binding energies of [Pr(III)(cis-TFSA)5]2-, [Nd(III)(cis-TFSA)5]2-, and [Dy(III)(cis-TFSA)5]2- clusters were also investigated by DFT calculations using the ADF

  4. Enantiomeric self-recognition in homo- and heterodinuclear macrocyclic lanthanide(III) complexes.

    PubMed

    Lisowski, Jerzy

    2011-06-20

    The controlled formation of lanthanide(III) dinuclear μ-hydroxo-bridged [Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes (where X = H(2)O, NO(3)(-), or Cl(-)) of the enantiopure chiral macrocycle L is reported. The (1)H and (13)C NMR resonances of these complexes have been assigned on the basis of COSY, NOESY, TOCSY, and HMQC spectra. The observed NOE connectivities confirm that the dimeric solid-state structure is retained in solution. The enantiomeric nature of the obtained chiral complexes and binding of hydroxide anions are reflected in their CD spectra. The formation of the dimeric complexes is accompanied by a complete enantiomeric self-recognition of the chiral macrocyclic units. The reaction of NaOH with a mixture of two different mononuclear lanthanide(III) complexes, [Ln(1)L](3+) and [Ln(2)L](3+), results in formation of the heterodinuclear [Ln(1)Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes as well as the corresponding homodinuclear complexes. The formation of the heterodinuclear complex is directly confirmed by the NOESY spectra of [EuLuL(2)(μ-OH)(2)(H(2)O)(2)](4+), which reveal close contacts between the macrocyclic unit containing the Eu(III) ion and the macrocyclic unit containing the Lu(III) ion. While the relative amounts of homo- and heterodinuclear complexes are statistical for the two lanthanide(III) ions of similar radii, a clear preference for the formation of heterodinuclear species is observed when the two mononuclear complexes contain lanthanide(III) ions of markedly different sizes, e.g., La(III) and Yb(III). The formation of heterodinuclear complexes is accompanied by the self-sorting of the chiral macrocyclic units based on their chirality. The reactions of NaOH with a pair of homochiral or racemic mononuclear complexes, [Ln(1)L(RRRR)](3+)/[Ln(2)L(RRRR)](3+), [Ln(1)L(SSSS)](3+)/[Ln(2)L(SSSS)](3+), or [Ln(1)L(rac)](3+)/[Ln(2)L(rac)](3+), results in mixtures of homochiral, homodinuclear and homochiral, heterodinuclear complexes. On the contrary, no

  5. Efficient phosphodiester hydrolysis by luminescent terbium(III) and europium(III) complexes.

    PubMed

    Camargo, Maryene A; Neves, Ademir; Bortoluzzi, Adailton J; Szpoganicz, Bruno; Fischer, Franciele L; Terenzi, Hernán; Serra, Osvaldo A; Santos, Vanessa G; Vaz, Boniek G; Eberlin, Marcos N

    2010-07-05

    The synthesis and structures of two new isostructural mononuclear [Ln(L)(NO(3))(H(2)O)(3)](NO(3))(2) complexes, with Ln = Tb (complex 1) and Eu (complex 2), which display high activity in the hydrolysis of the substrate 2,4-bis(dinitrophenyl)phosphate, are reported. These complexes displayed catalytic behavior similar to the mononuclear gadolinium complex [Gd(L)(NO(3))(H(2)O)(3)](NO(3))(2) previously reported by us (Inorg. Chem. 2008, 47, 2919-2921); one hydrolysis reaction in two stages where the diesterase and monoesterase activities could be monitored separately, with the first stage dependent on and the second independent of the complex concentration. Through potentiometric studies, electrospray ionization mass spectrometry (ESI-MS) analysis, and determination of the kinetic behaviors of 1 and 2 in acetonitrile/water solution, the species present in solution could be identified and suggested a dinuclear species, with one hydroxo group, as the most prominent catalyst under mild conditions. The complexes show high activity (k(1) = 7 and 18 s(-1) for 1 and 2, respectively) and catalytic efficiency. Complexes 1 and 2 were found to be active toward the cleavage of plasmid DNA, and complete kinetic studies were carried out. Studies with a radical scavenger (dimethylsulfoxide) confirmed the hydrolytic action of 1 and 2 in the cleavage of DNA. Studies on the incubation of distamycin with plasmid DNA suggested that 1 and 2 are regio-specific, interacting with the minor groove of DNA. These complexes displayed luminescent properties. Complex 1 showed higher emission intensity than 2 due to a more efficient energy transfer between triplet and emission levels of terbium (T --> (5)D(4)), along with nonradiative deactivation mechanisms of the excited states of europium via multiphonon decays and the ligand-to-metal charge transfer state. Lifetime measurements of the (5)D(4) and (5)D(0) excited levels for 1 and 2, respectively, indicated the numbers of coordinated water

  6. Impact of Type I and III Interferons on Respiratory Superinfections Due to Multidrug-Resistant Pathogens.

    PubMed

    Parker, Dane

    2017-02-15

    The increased morbidity and mortality associated with bacterial pneumonias that are acquired following influenza infection are well appreciated by clinicians. One of the major components of the immune response to influenza is the induction of the types I and III interferon cascades, which encompasses the activation of over 300 genes. The immunological consequences of IFN activation, while important for viral clearance, modify the host proinflammatory responses through effects on the inflammasome, Th17 signaling and recruitment of phagocytic cells. IFN signaling affects both susceptibility to subsequent Streptococcus pneumoniae and Staphylococcus aureus infection as well as the intensity of the immune responses associated with pulmonary damage. Appreciation for the effects of IFN activation on anti-bacterial pulmonary defense mechanisms should help to inform therapeutic strategies in an ICU setting. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  7. The Deactive Form of Respiratory Complex I from Mammalian Mitochondria Is a Na+/H+ Antiporter*

    PubMed Central

    Roberts, Philippa G.; Hirst, Judy

    2012-01-01

    In mitochondria, complex I (NADH:ubiquinone oxidoreductase) uses the redox potential energy from NADH oxidation by ubiquinone to transport protons across the inner membrane, contributing to the proton-motive force. However, in some prokaryotes, complex I may transport sodium ions instead, and three subunits in the membrane domain of complex I are closely related to subunits from the Mrp family of Na+/H+ antiporters. Here, we define the relationship between complex I from Bos taurus heart mitochondria, a close model for the human enzyme, and sodium ion transport across the mitochondrial inner membrane. In accord with current consensus, we exclude the possibility of redox-coupled Na+ transport by B. taurus complex I. Instead, we show that the “deactive” form of complex I, which is formed spontaneously when enzyme turnover is precluded by lack of substrates, is a Na+/H+ antiporter. The antiporter activity is abolished upon reactivation by the addition of substrates and by the complex I inhibitor rotenone. It is specific for Na+ over K+, and it is not exhibited by complex I from the yeast Yarrowia lipolytica, which thus has a less extensive deactive transition. We propose that the functional connection between the redox and transporter modules of complex I is broken in the deactive state, allowing the transport module to assert its independent properties. The deactive state of complex I is formed during hypoxia, when respiratory chain turnover is slowed, and may contribute to determining the outcome of ischemia-reperfusion injury. PMID:22854968

  8. Imbalance of Mitochondrial Respiratory Chain Complexes in the Epidermis Induces Severe Skin Inflammation.

    PubMed

    Weiland, Daniela; Brachvogel, Bent; Hornig-Do, Hue-Tran; Neuhaus, Johannes F G; Holzer, Tatjana; Tobin, Desmond J; Niessen, Carien M; Wiesner, Rudolf J; Baris, Olivier R

    2017-08-31

    Accumulation of large-scale mitochondrial DNA (mtDNA) deletions and chronic, subclinical inflammation are concomitant during skin aging, thus raising the question of a causal link. To approach this, we generated mice expressing a mutant mitochondrial helicase (K320E-TWINKLE) in the epidermis in order to accelerate the accumulation of mtDNA deletions in this skin compartment. Mice displayed low amounts of large-scale deletions as well as a dramatic depletion of mtDNA in the epidermis and showed macroscopic signs of severe skin inflammation. The mtDNA alterations led to an imbalanced stoichiometry of mitochondrial respiratory chain complexes, inducing a unique combination of cytokine expression, causing a severe inflammatory phenotype, with massive immune cell infiltrates already before birth. Altogether, these data unraveled a previously unknown link between an imbalanced stoichiometry of the mitochondrial respiratory chain complexes and skin inflammation, and suggest that severe respiratory chain dysfunction, as observed in few cells leading to a mosaic in aged tissues, might be involved in the development of chronic sub-clinical inflammation. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Cytotoxic activity of new cerium (III) complexes of bis-coumarins.

    PubMed

    Kostova, Irena; Manolov, Ilia; Momekov, Georgi; Tzanova, Tzvetomira; Konstantinov, Spiro; Karaivanova, Margarita

    2005-12-01

    Complexes of cerium (III) with bis-coumarins: 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane were synthesized by reaction of cerium (III) salt and the ligands, in amounts equal to metal/ligand molar ratio of 1:2. The complexes were prepared by adding an aqueous solution of cerium (III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to ca. 5.0 by adding dilute solution of sodium hydroxide. The cerium (III) complexes with bis-coumarins were characterized by different physicochemical methods--elemental analysis, IR-, 1H- and 13C-NMR-spectroscopies and mass-spectral data. The spectral data of cerium (III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the Ce (III) complexes the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the nu(C=O) red shift observed, participation of the carbonyl groups in the coordination to the metal ion was also suggested. Cytotoxic screening by MTT assay was carried out. In the present study we performed comparative evaluation of the cytotoxic effects of the two newly synthesized cerium complexes against the acute myeloid leukemia derived HL-60 and the chronic myeloid leukemia (CML)-derived BV-173. In addition the cytotoxic effects of Ce (III) complex with 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) were evaluated on the CML-derived K-562 and LAMA-84 cells, characterized by relative low responsiveness to chemotherapy. The DNA isolated from the cytosolic fraction of BV-173 cells after 24 h treatment with the same complex (at 100 and 200 microM) demonstrated a laddering phenomenon that is indicative for apoptotic cell death.

  10. New Bismuth(III), Lanthanum(III), Praseodymium (III), and Heterodinuclear Bi-La and Bi-Pr Complexes with Polyaminocarboxylate Ligands

    NASA Astrophysics Data System (ADS)

    Wullens, H.; Bodart, N.; Devillers, M.

    2002-09-01

    New Bi(III), La(III) and Pr(III) complexes with a variety of high-denticity polyaminocarboxylic acids (H 4edta, H 5dtpa, H 6ttha, H 4Cydta, H 5hpdta, H 4egta) have been synthesized and characterized spectroscopically by FTIR. In the case of the decadentate ttha ligand, homodinuclear M2(ttha) ( M=Bi, La, Pr) and heterodinuclear MM'(ttha) complexes were isolated. Detailed investigations of their thermal degradation scheme were carried out in relationship with the possible use of these complexes as molecular precursors for the formation of mixed Bi-La and Bi-Pr oxides in which the crystal structure of the fluorite-like δ-Bi 2O 3 phase can be stabilized at room temperature. Decomposition proceeds in three successive stages, consisting of dehydration, ligand pyrolysis leading to monoxo-, dioxo- or simple carbonates, depending on the metal nature, and finally decarbonatation producing the corresponding oxide: α-Bi 2O 3, La 2O 3, Pr 6O 11, BiLaO 3 or BiPrO 3.

  11. Single Pathogen Challenge with Agents of the Bovine Respiratory Disease Complex.

    PubMed

    Gershwin, Laurel J; Van Eenennaam, Alison L; Anderson, Mark L; McEligot, Heather A; Shao, Matt X; Toaff-Rosenstein, Rachel; Taylor, Jeremy F; Neibergs, Holly L; Womack, James

    2015-01-01

    Bovine respiratory disease complex (BRDC) is an important cause of mortality and morbidity in cattle; costing the dairy and beef industries millions of dollars annually, despite the use of vaccines and antibiotics. BRDC is caused by one or more of several viruses (bovine respiratory syncytial virus, bovine herpes type 1 also known as infectious bovine rhinotracheitis, and bovine viral diarrhea virus), which predispose animals to infection with one or more bacteria. These include: Pasteurella multocida, Mannheimia haemolytica, Mycoplasma bovis, and Histophilus somni. Some cattle appear to be more resistant to BRDC than others. We hypothesize that appropriate immune responses to these pathogens are subject to genetic control. To determine which genes are involved in the immune response to each of these pathogens it was first necessary to experimentally induce infection separately with each pathogen to document clinical and pathological responses in animals from which tissues were harvested for subsequent RNA sequencing. Herein these infections and animal responses are described.

  12. Single Pathogen Challenge with Agents of the Bovine Respiratory Disease Complex

    PubMed Central

    Gershwin, Laurel J.; Van Eenennaam, Alison L.; Anderson, Mark L.; McEligot, Heather A.; Toaff-Rosenstein, Rachel; Taylor, Jeremy F.; Neibergs, Holly L.; Womack, James

    2015-01-01

    Bovine respiratory disease complex (BRDC) is an important cause of mortality and morbidity in cattle; costing the dairy and beef industries millions of dollars annually, despite the use of vaccines and antibiotics. BRDC is caused by one or more of several viruses (bovine respiratory syncytial virus, bovine herpes type 1 also known as infectious bovine rhinotracheitis, and bovine viral diarrhea virus), which predispose animals to infection with one or more bacteria. These include: Pasteurella multocida, Mannheimia haemolytica, Mycoplasma bovis, and Histophilus somni. Some cattle appear to be more resistant to BRDC than others. We hypothesize that appropriate immune responses to these pathogens are subject to genetic control. To determine which genes are involved in the immune response to each of these pathogens it was first necessary to experimentally induce infection separately with each pathogen to document clinical and pathological responses in animals from which tissues were harvested for subsequent RNA sequencing. Herein these infections and animal responses are described. PMID:26571015

  13. Versatile bonding and coordination modes of ditriazolylidene ligands in rhodium(iii) and iridium(iii) complexes.

    PubMed

    Farrell, Kevin; Müller-Bunz, Helge; Albrecht, Martin

    2016-10-12

    Metalation of novel ditriazolium salts containing a trimethylene (-CH2CH2CH2-) or dimethylether linker (-CH2OCH2-) was probed with different rhodium(iii) and iridium(iii) precursors. When using [MCp*Cl2]2, a transmetalation protocol via a triazolylidene silver intermediate was effective, while base-assisted metalation with MCl3via sequential deprotonation of the triazolium salt with KOtBu and addition of the metal precursor afforded homoleptic complexes. The N-substituent on the triazole heterocycle directed the metalation process and led to Ctrz,Ctrz,CPh-tridentate chelating ditriazolylidene complexes for N-phenyl substituents. With ethyl substituents, only Ctrz,Ctrz-bidentate complexes were formed, while metalation with mesityl substituents was unsuccessful, presumably due to steric constraints. Through modification of the reaction conditions for the metalation step, an intermediate species was isolated that contains a Ctrz,CPh-bidentate chelate en route to the formation of the tridentate ligand system. Accordingly, Cphenyl-H bond activation occurs prior to formation of the second metal-triazolylidene bond. Stability studies with a Ctrz,Ctrz,CPh-tridentate chelating ditriazolylidene iridium complex towards DCl showed deuterium incorporation at both N-phenyl groups and indicate that Cphenyl-H bond activation is reversible while the Ctrz-Ir bond is robust. The flexible linker between the two triazolylidene donor sites provides access to both facial and meridional coordination modes.

  14. Organometallic rhodium(III) and iridium(III) cyclopentadienyl complexes with curcumin and bisdemethoxycurcumin co-ligands.

    PubMed

    Pettinari, Riccardo; Marchetti, Fabio; Pettinari, Claudio; Condello, Francesca; Petrini, Agnese; Scopelliti, Rosario; Riedel, Tina; Dyson, Paul J

    2015-12-21

    A series of half-sandwich cyclopentadienyl rhodium(III) and iridium(III) complexes of the type [Cp*M(curc/bdcurc)Cl] and [Cp*M(curc/bdcurc)(PTA)][SO3CF3], in which Cp* = pentamethylcyclopentadienyl, curcH = curcumin and bdcurcH = bisdemethoxycurcumin as O^O-chelating ligands, and PTA = 1,3,5-triaza-7-phosphaadamantane, is described. The X-ray crystal structures of three of the complexes, i.e. [Cp*Rh(curc)(PTA)][SO3CF3] (5), [Cp*Rh(bdcurc)(PTA)][SO3CF3] (6) and [Cp*Ir(bdcurc)(PTA)][SO3CF3] (8), confirm the expected "piano-stool" geometry. With the exception of 5, the complexes are stable under pseudo-physiological conditions and are moderately cytotoxic to human ovarian carcinoma (A2780 and A2780cisR) cells and also to non-tumorigenic human embryonic kidney (HEK293) cells, but lack the cancer cell selectivity observed for related arene ruthenium(II) complexes.

  15. Equilibrium Fe isotope fractionation between inorganic aqueous Fe(III) and the siderophore complex, Fe(III)-desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Dideriksen, K.; Baker, J. A.; Stipp, S. L. S.

    2008-05-01

    In oxic oceans, most of the dissolved iron (Fe) exists as complexes with siderophore-like, strongly coordinating organic ligands. Thus, the isotope composition of the little amount of free inorganic Fe that is available for precipitation and preservation in the geological record may largely be controlled by isotope fractionation between the free and complexed iron. We have determined the equilibrium Fe isotope fractionation induced by organic ligand activity in experiments with solutions having co-existing inorganic Fe(III) species and siderophore complexes, Fe-desferrioxamine B (at pH 2). The two differently complexed Fe(III) pools were separated by addition of Na 2CO 3, which led to immediate precipitation of the inorganic Fe without causing significant dissociation of Fe-desferrioxamine complexes. Experiments using enriched 57Fe tracer showed that isotopic equilibration between the 57Fe-labelled inorganic species and the isotopically "normal" siderophore-bound Fe was rapid during the first few seconds and then became slower. Consequently, the data fitted poorly to first and second order reaction equations. However, with a two-stage reaction, the data fit perfectly with a first order equation for the slower stage, indicating that approximately 40% re-equilibration may take place during the separation of the two pools. To further test if the induced precipitation leads to experimental artefacts, the fractionation during precipitation of inorganic Fe was determined. Assuming a Rayleigh-type fractionation during precipitation, this experiment yielded an isotope fractionation factor of α56Fe solution-solid = 1.00027. Calculations based on these results indicate that isotopic re-equilibration is unlikely to significantly affect our determined equilibrium Fe isotope fractionation between inorganically and organically complexed Fe. To determine the equilibrium Fe isotope fractionation between inorganically and organically bound Fe(III), experiments with variable

  16. Complexation Studies of Bidentate Heterocyclic N-Donor Ligands with Nd(III) and Am(III)

    SciTech Connect

    Ogden, Mark; Hoch, Courtney L.; Sinkov, Sergey I.; Meier, Patrick; Lumetta, Gregg J.; Nash, Kenneth L.

    2011-11-28

    A new bidentate nitrogen donor complexing agent that combines pyridine and triazole functional groups, 2-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyridine (PTMP), has been synthesized. The strength of its complexes with trivalent americium (Am3+) and neodymium (Nd3+) in anhydrous methanol has been evaluated using spectrophotometric techniques. The purpose of this investigation is to assess this ligand (as representative of a class of similarly structured species) as a possible model compound for the challenging separation of trivalent actinides from lanthanides. This separation, important in the development of advanced nuclear fuel cycles, is best achieved through the agency of multidentate chelating agents containing some number of nitrogen or sulfur donor groups. To evaluate the relative strength of the bidentate complexes, the derived constants are compared to those of the same metal ions with 2,2*-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2-pyridin-2-yl-1H-benzimidazole (PBIm). At issue is the relative affinity of the triazole moiety for trivalent f element ions. For all ligands, the derived stability constants are higher for Am3+ than Nd3+. In the case of Am3+ complexes with phen and PBIm, the presence of 1:2 (AmL2) species is indicated. Possible separations are suggested based on the relative stability and stoichiometry of the Am3+ and Nd3+ complexes. It can be noted that the 1,2,3-triazolyl group imparts a potentially useful selectivity for trivalent actinides (An(III)) over trivalent lanthanides (Ln(III)), though the attainment of higher complex stoichiometries in actinide compared with lanthanide complexes may be an important driver for developing successful separations.

  17. Synthesis, characterisation and biological evaluation of lanthanide(III) complexes with 3-acetylcoumarin-o-aminobenzoylhydrazone (ACAB).

    PubMed

    Gudasi, Kalagouda B; Shenoy, Rashmi V; Vadavi, Ramesh S; Patil, Manjula S; Patil, Siddappa A

    2005-09-01

    Lanthanide(III) complexes of the general formula [Ln(ACAB)(2)(NO(3))(2)(H(2)O)(2)].NO(3).H(2)O where Ln=La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III) and Y(III), ACAB=3-acetylcoumarin-o-aminobenzoylhydrazone have been isolated and characterised based on elemental analyses, molar conductance, IR, (1)H- and (13)C-NMR, UV, TG/DTA and EPR spectral studies. The ligand behaves in bidentate fashion coordinating through hydrazide >C=O and nitrogen of >C=N. A coordination number of ten is assigned to the complexes. Antibacterial and Antifungal studies indicate an enhancement of activity of the ligand on complexation.

  18. Characterization of Hydrogen Complex Formation in III-V Semiconductors

    SciTech Connect

    Williams, Michael D

    2006-09-28

    Atomic hydrogen has been found to react with some impurity species in semiconductors. Hydrogenation is a methodology for the introduction of atomic hydrogen into the semiconductor for the express purpose of forming complexes within the material. Efforts to develop hydrogenation as an isolation technique for AlGaAs and Si based devices failed to demonstrate its commercial viability. This was due in large measure to the low activation energies of the formed complexes. Recent studies of dopant passivation in long wavelength (0.98 - 1.55m) materials suggested that for the appropriate choice of dopants much higher activation energies can be obtained. This effort studied the formation of these complexes in InP, This material is extensively used in optoelectronics, i.e., lasers, modulators and detectors. The experimental techniques were general to the extent that the results can be applied to other areas such as sensor technology, photovoltaics and to other material systems. The activation energies for the complexes have been determined and are reported in the scientific literature. The hydrogenation process has been shown by us to have a profound effect on the electronic structure of the materials and was thoroughly investigated. The information obtained will be useful in assessing the long term reliability of device structures fabricated using this phenomenon and in determining new device functionalities.

  19. Plane Transformations in a Complex Setting III: Similarities

    ERIC Educational Resources Information Center

    Dana-Picard, Thierry

    2009-01-01

    This is the third part of a study of plane transformations described in a complex setting. After the study of homotheties, translations, rotations and reflections, we proceed now to the study of plane similarities, either direct or inverse. Their group theoretical properties are described, and their action on classical geometrical objects is…

  20. Luminescent chemosensors for amines and ammonia based on Eu(III) chelate complexes

    NASA Astrophysics Data System (ADS)

    Sergeev, Alexander A.; Voznesenskiy, Sergey S.; Petrochenkova, Nataliya V.; Shishov, Alexander S.; Leonov, Andrei A.; Emelina, Tatiana B.; Mirochnik, Anatolii G.; Kulchin, Yuri N.

    2016-11-01

    Here we report a novel luminescent sensor for amines and ammonia based on Eu(III) tris-β-benzoylacetonate complexes obtained in various conditions. It has been revealed that interaction of Eu(III) tris-β-benzoylacetonate with analyte vapor results in increase of the Eu(III) luminescence intensity. Exposure of Eu(III) complexes to ammonia and methylamine vapors results in a rapid increase of the emission and excitation spectra intensity and a rapid recovery, almost to the initial value, when the sample is exposed to air. Moreover, luminescence decay time value of Eu(III) complexes is in dependence on analyte presence and increase in ammonia atmosphere and decrease under purging of pure air. The dependences of sensor response features upon preparation conditions were shown. The mechanism of the analyte vapors effect on Eu(III) luminescence intensification has been suggested using the data of IR spectroscopy and quantum chemistry calculations. The mechanism of luminescence sensitization consists in bonding of an analyte molecule with a water molecule into the coordination sphere of Eu(III). As a result, the bond of a water molecule with the luminescence center weakens and the blockage of the quenching of luminescence on OH-vibrations takes place. The obtained data can be used for development of sensor materials with selective optical sensitivity to ecologically harmful vapours of organic and inorganic compounds.

  1. [Synthesis of hydroxamic acids and study of their complexes with iron (II) and (III) ions].

    PubMed

    Nenortiene, Palma; Sapragoniene, Marija; Stankevicius, Antanas

    2002-01-01

    Hydroxamic acids are widespread in the tissues of plants, in metabolites of bacteria and fungi, including complex compounds with metal ions. These acids have wide spectrum of biological activity and therefore are perspective reagents for analysis of chemical elements. Fourteen aliphatic and aromatic derivatives of hydroxamic acids have been synthesized from esters of carboxylic acids. Photometric reactions of hydroxamic acids with iron (II) and (III) were investigated. Complex formation of iron (II) and (III) depending on pH was studied with series of synthesized hydroxamic acids: octanohydroxamic, maleic hydroxamic, 2-hydroxybenzoxydroxamic, benzoxydroxamic, phthalmonoxydroxamic and 3-metoxybenzohydroxamic acids. Composition of iron (III) complexes with 2-hydroxybenzohydroxamic, octanoxydroxamic, 3-metoxybenzohydroxamic acids and iron (II) with 2-hydroxybenzohydroxamic acid was studied by methods of mole ratio and isomolar solutions. Sensitivity of reagents was evaluated by values of absorption coefficients (epsilon). Stability of complexes in water and organic solvents was investigated. Interaction between iron (III) and hydroxamic acids (octanoxydroxamic, 2-hydroxybenzohydroxamic, 3-metoxybenzohydroxamic) have been applied for quantitative photometric analysis of iron (III) salts. Color reaction of iron (II) with 2-hydroxybenzohydroxamic acid was applied for quantitative photometric determination of iron (II) salts. 3-Metoxybenzohydroxamic acid was proposed as a new indicator for complexonometric analysis of iron (III). Chelatometric titration of iron (III) using this indicator is not influenced by copper, cobalt, zinc, manganese, so this methods is recommended for iron quantity detection in antianemic drugs, which are composed of latter microelements. Synthesis procedure of 2-benzoylamino-3-arylacrylhydroxamic acids from saturated azlactones was created. Color and precipitate reactions of iron (II) and (III), copper (II), nickel (II) and cobalt (II) ions with

  2. Efficient removal of Cr(III)-organic complexes from water using UV/Fe(III) system: Negligible Cr(VI) accumulation and mechanism.

    PubMed

    Ye, Yuxuan; Jiang, Zhao; Xu, Zhe; Zhang, Xiaolin; Wang, Dandan; Lv, Lu; Pan, Bingcai

    2017-09-13

    Most available processes are incapable of removing Cr(III)-organic complexes from water due to their high solubility, extremely slow decomplexation rate, and possible formation of more toxic Cr(VI) during oxidation. Herein, we proposed a new combined process, i.e., UV/Fe(III) followed by alkaline precipitation (namely UV/Fe(III)+OH), to achieve highly efficient and environmentally benign removal of Cr(III)-organic complexes from water. The combined process could remove Cr(III)-citrate from 10.4 mg Cr/L to 0.36 mg Cr/L and ∼60% total organic carbon as well. More attractively, negligible Cr(VI) (<0.06 mg/L) was formed during the process. In the viewpoint of mechanism, the added Fe(III) generates ·OH radicals to transform Cr(III) into Cr(VI) and simultaneously released the citrate ligand to form Fe(III)-citrate simultaneously. Then, the photolysis of Fe(III)-citrate under UV irradiation involved the citrate degradation and the production of massive Fe(II) species, which in turn transformed the formed Cr(VI) back to Cr(III). The free metal ions, including Cr(III), Fe(II) and Fe(III) were removed by the subsequent alkaline precipitation. Also, the combined process is applicable to other Cr(III) complexes with EDTA, tartrate, oxalate, acetate. The applicability of the combined process was further demonstrated by treating two real tanning effluents, resulting in the residual Cr(III) below 1.5 mg/L (the discharge standard of China) and negligible formation of Cr(VI) (<0.004 mg/L) as well. In general, the combined process has a great potential for efficient removal of Cr(III) complexes from contaminated waters. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Cyanide-bridged Mn(III)-Fe(III) bimetallic complexes based on the pentacyano(1-methylimidazole)ferrate(III) building block: structure and magnetic characterizations.

    PubMed

    Ni, Wei-Wei; Ni, Zhong-Hai; Cui, Ai-Li; Liang, Xin; Kou, Hui-Zhong

    2007-01-08

    Seven cyanide-bridged bimetallic complexes have been synthesized by the reaction of [Fe(1-CH3im)(CN)5]2- with Mn(III) Schiff base complexes. Their crystal structure and magnetic properties have been characterized. Five complexes, [Mn2(5-Brsalen)2Fe(CN)5(1-CH3im)] x H2O (1), [Mn2(5-Clsalen)2(H2O)2Fe(CN)5(1-CH3im)] x H2O (2), [Mn2(5-Clsaltn)2(H2O)2Fe(CN)5(1-CH3im)] (3), [Mn2(5-Clsaltmen)2(H2O)2Fe(CN)5(1-CH3im)] x H2O (4), and [Mn2(5-Brsaltmen)2(H2O)2Fe(CN)5(1-CH3im)] x CH3OH (5), are neutral and trinuclear with two [Mn(SB)]+ (SB2- = Schiff base ligands) and one [Fe(1-CH3im)(CN)5]2-. Complex {[Et4N][Mn(acacen)Fe(CN)5(1-CH3im)]}n x 6nH2O (6) is one-dimensional with alternate [Mn(acacen)]+ and [Fe(CN)5(1-CH3im)]2- units. The two-dimensional complex {[Mn4(saltmen)4Fe(CN)5(1-CH3im)]}n[ClO4]2n x 9nH2O (7) consists of Mn4Fe units which are further connected by the phenoxo oxygen atoms. Magnetic studies show the presence of ferromagnetic Mn(III)-Fe(III) coupling in the trinuclear compounds with the magnetic coupling constant (J) ranging from 4.5 to 6.0 cm-1, based on the Hamiltonian H = -2JSFe(SMn(1) + SMn(2)). Antiferromagnetic interaction has been observed in complex 6, whereas ferromagnetic coupling occurs in complex 7. Complexes 6 and 7 exhibit long-range magnetic ordering with a TN value of 4.0 K for 6 and Tc of 4.8 K for 7. Complex 6 shows metamagnetic behavior at 2 K, and complex 7 possesses a hysteresis loop with a coercive field of 500 Oe, typical of a soft ferromagnet.

  4. Synthesis and comparative anion binding profiles of two di-aqua Eu(III) complexes.

    PubMed

    Imperio, Daniela; Giovenzana, Giovanni B; Law, Ga-Lai; Parker, David; Walton, James W

    2010-11-07

    Two di-aqua Eu(iii) complexes of heptadentate ligands are reported that show differing reactivity profiles towards various anions; a cationic complex with two azaxanthone moieties exhibits pronounced selectivity towards bicarbonate with an affinity constant, logK = 2.65 (295 K, 0.1 M NaCl).

  5. Luminescent biscarbene iridium(III) complexes as living cell imaging reagents.

    PubMed

    Zhou, Yuyang; Jia, Junli; Li, Wanfei; Fei, Hao; Zhou, Ming

    2013-04-21

    Five iridium(III) complexes with two N-heterocyclic carbene (NHC) ligands and an ancillary ligand have been designed and successfully synthesized. With multicolor photoluminescence and low toxicity, these carbene complexes were tested, for the first time, as living cell imaging reagents and showed promise for application beyond the OLED (organic light emitting diode) area.

  6. Synthesis and characterization of a new Inonotus obliquus polysaccharide-iron(III) complex.

    PubMed

    Wang, Jia; Chen, Haixia; Wang, Yanwei; Xing, Lisha

    2015-04-01

    A new Inonotus obliquus polysaccharide-iron(III) complex (IOPS-iron) was synthesized and characterized. The preparation conditions of IOPS-iron(III) were optimized and the physicochemical properties were characterized by physicochemical methods, scanning electron microscopy (SEM), electron paramagnetic resonance (EPR) spectroscopy, fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, respectively. The highest iron content of IOPS-iron(III) complex (19.40%) was obtained at the conditions: the ratio of IOPS and FeCl3 • 6H2O was 3:5 (w/w), the pH value of alkali solution was 10, the reaction temperature was 30 °C and the reaction time was 6h. The iron(III) was shown to be bound through the binding sites of the polysaccharide IOPS and it could form spatially separated iron centers on the polysaccharide backbone. IOPS-iron(III) complex was found to have good digestive availability and antioxidant activities in the in vitro assays, which suggested the IOPS-iron(III) complex might be used as a new iron supplement candidate.

  7. Enantioselective epoxidation of non-functionalized alkenes using carbohydrate based salen-Mn(III) complexes.

    PubMed

    Zhao, Shanshan; Zhao, Jiquan; Zhao, Dongmin

    2007-02-05

    Three new salen ligands with carbohydrate moieties were prepared from a salicylaldehyde derivative obtained by reaction of 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose with 3-tert-butyl-5-(chloro-methyl)-2-hydroxybenzaldehyde. These ligands were coordinated with Mn(III) to give three chiral salen-Mn(III) complexes. The complexes were characterized and employed in the asymmetric epoxidation of unfunctionalized alkenes. Catalytic results showed that although there are no chiral groups on the diimine bridge, these complexes had some enantioselectivity, which indicates the carbohydrate moiety has an asymmetric inducing effect in the epoxidation reaction.

  8. Synthesis, Characterization, and Antifungal Studies of Cr(III) Complex of Norfloxacin and Bipiridyl Ligand

    PubMed Central

    Debnath, Anamika; Hussain, Firasat; Masram, Dhanraj T.

    2014-01-01

    A novel slightly distorted octahedral complex of Cr(III) of norfloxacin (Nor) with the formula [CrIII(Nor)(Bipy)Cl2]Cl·2CH3OH has been synthesized hydrothermally in the presence of a N-containing heterocyclic compound 2,2′-bipyridyl (Bipy). The complex was characterized with FT-IR, elemental analysis, UV-visible spectroscopy, and X-ray crystallography. Spectral studies suggest that the Nor acts as a deprotonated bidentate ligand. Thermal studies were also carried out. The synthesised complex was screened against four fungi Pythium aphanidermatum (PA), Sclerotinia rolfsii (SR), Rhizoctonia solani (RS), and Rhizoctonia bataticola (RB). PMID:25276111

  9. Highly efficient electrochemiluminescence from iridium(III) complexes with 2-phenylquinoline ligand.

    PubMed

    Zhou, Yuyang; Li, Wanfei; Yu, Linpo; Liu, Yang; Wang, Xiaomei; Zhou, Ming

    2015-01-28

    A series of cyclometalated iridium(III) complexes with 2-phenylquinoline ligand (1-4) were designed and synthesized, which were thoroughly investigated by the photophysics, electrochemistry, theoretical calculations and electrochemiluminescence (ECL). By incorporating methyl groups into the 2-phenylquinoline, the corresponding complexes 2 and 3 displayed lower oxidative potential and higher HOMO energy levels. Most importantly, compared with tris(2,2'-bipyridyl)ruthenium(II) ([Ru(bipy)3](2+)), these iridium(III) complexes demonstrated more intense ECL in acetonitrile solutions.

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

    PubMed

    Ahmed, Zubair; Iftikhar, K

    2013-11-07

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

  11. Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

    PubMed

    Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

    2013-03-04

    Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

  12. [Tl(III)(dota)](-): An Extraordinarily Robust Macrocyclic Complex.

    PubMed

    Fodor, Tamás; Bányai, István; Bényei, Attila; Platas-Iglesias, Carlos; Purgel, Mihály; Horváth, Gábor L; Zékány, László; Tircsó, Gyula; Tóth, Imre

    2015-06-01

    The X-ray structure of {C(NH2)3}[Tl(dota)]·H2O shows that the Tl(3+) ion is deeply buried in the macrocyclic cavity of the dota(4-) ligand (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate) with average Tl-N and Tl-O distances of 2.464 and 2.365 Å, respectively. The metal ion is directly coordinated to the eight donor atoms of the ligand, which results in a twisted square antiprismatic (TSAP') coordination around Tl(3+). A multinuclear (1)H, (13)C, and (205)Tl NMR study combined with DFT calculations confirmed the TSAP' structure of the complex in aqueous solution, which exists as the Λ(λλλλ)/Δ(δδδδ) enantiomeric pair. (205)Tl NMR spectroscopy allowed the protonation constant associated with the protonation of the complex according to [Tl(dota)](-) + H(+) ⇆ [Tl(Hdota)] to be determined, which turned out to be pK(H)Tl(dota) = 1.4 ± 0.1. [Tl(dota)](-) does not react with Br(-), even when using an excess of the anion, but it forms a weak mixed complex with cyanide, [Tl(dota)](-) + CN(-) ⇆ [Tl(dota)(CN)](2-), with an equilibrium constant of Kmix = 6.0 ± 0.8. The dissociation of the [Tl(dota)](-) complex was determined by UV-vis spectrophotometry under acidic conditions using a large excess of Br(-), and it was found to follow proton-assisted kinetics and to take place very slowly (∼10 days), even in 1 M HClO4, with the estimated half-life of the process being in the 10(9) h range at neutral pH. The solution dynamics of [Tl(dota)](-) were investigated using (13)C NMR spectroscopy and DFT calculations. The (13)C NMR spectra recorded at low temperature (272 K) point to C4 symmetry of the complex in solution, which averages to C4v as the temperature increases. This dynamic behavior was attributed to the Λ(λλλλ) ↔ Δ(δδδδ) enantiomerization process, which involves both the inversion of the macrocyclic unit and the rotation of the pendant arms. According to our calculations, the arm-rotation process limits the Λ(λλλλ) ↔

  13. Cryo-EM structure of respiratory complex I reveals a link to mitochondrial sulfur metabolism.

    PubMed

    D'Imprima, Edoardo; Mills, Deryck J; Parey, Kristian; Brandt, Ulrich; Kühlbrandt, Werner; Zickermann, Volker; Vonck, Janet

    2016-12-01

    Mitochondrial complex I is a 1MDa membrane protein complex with a central role in aerobic energy metabolism. The bioenergetic core functions are executed by 14 central subunits that are conserved from bacteria to man. Despite recent progress in structure determination, our understanding of the function of the ~30 accessory subunits associated with the mitochondrial complex is still limited. We have investigated the structure of complex I from the aerobic yeast Yarrowia lipolytica by cryo-electron microscopy. Our density map at 7.9Å resolution closely matches the 3.6-3.9Å X-ray structure of the Yarrowia lipolytica complex. However, the cryo-EM map indicated an additional subunit on the side of the matrix arm above the membrane surface, pointing away from the membrane arm. The density, which is not present in any previously described complex I structure and occurs in about 20 % of the particles, was identified as the accessory sulfur transferase subunit ST1. The Yarrowia lipolytica complex I preparation is active in generating H2S from the cysteine derivative 3-mercaptopyruvate, catalyzed by ST1. We thus provide evidence for a link between respiratory complex I and mitochondrial sulfur metabolism. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Activities of respiratory chain complexes and citrate synthase influenced by pharmacologically different antidepressants and mood stabilizers.

    PubMed

    Hroudova, Jana; Fisar, Zdenek

    2010-01-01

    Mitochondrial dysfunctions, impaired bioenergetics and dysfunction of neurotrophins are included in many neurodegenerative and psychiatric diseases. We investigated in vitro effects of pharmacologically different antidepressants and mood stabilizers on mitochondrial enzymes to discover, which mitochondrial functions could be involved in pathophysiology of mood disorders. In vitro effects of eight pharmacologically different antidepressants (desipramine, amitriptyline, imipramine, citalopram, venlafaxine, mirtazapine, tianeptine, and moclobemide) and three mood stabilizers (lithium, valproate, and olanzapine) on the activities of mitochondrial enzymes (citrate synthase and enzymes in electron transport chain, i.e. complexes I, II, IV) were measured in crude mitochondrial fraction isolated from pig brain. Most of the antidepressants and mood stabilizers inhibited the activities of respiratory electron transport chain complexes, complexes I and IV were the most affected. Statistically significant decrease of the complex I activity was caused by desipramine, amitriptyline, imipramine, citalopram, mirtazapine, valproate and olanzapine. Complex II was significantly inhibited only by amitriptyline, imipramine, citalopram and venlafaxine. Complex IV was significantly inhibited by all tested drugs except for citalopram and moclobemide. Unchanged or slightly increased citrate synthase activity was observed; significant activation of the enzyme was observed after citalopram, tianeptine and olanzapine. Our results indicate that antidepressants may act generally as inhibitors of complex I and complex IV of the electron transport chain. These mitochondrial enzymes are suggested as proper candidates in searching of new biological markers of mood disorders, targets of new antidepressants or predictors of response to pharmacotherapy.

  15. Redefining the roles of mitochondrial DNA-encoded subunits in respiratory Complex I assembly

    PubMed Central

    Vartak, Rasika; Deng, Janice; Fang, Hezhi; Bai, Yidong

    2015-01-01

    Respiratory Complex I deficiency is implicated in numerous degenerative and metabolic diseases. In particular, mutations in several mitochondrial DNA (mtDNA)-encoded Complex I subunits including ND4, ND5 and ND6 have been identified in several neurological diseases. We previously demonstrated that these subunits played essential roles in Complex I assembly which in turn affected mitochondrial function. Here, we carried out a comprehensive study of the Complex I assembly pathway. We identified a new Complex I intermediate containing both membrane and matrix arms at an early assembly stage. We find that lack of the ND6 subunit does not hinder membrane arm formation; instead it recruits ND1 and ND5 enter the intermediate. While ND4 is important for the formation of the newly identified intermediate, the addition of ND5 stabilizes the complex and is required for the critical transition from Complex I to supercomplexes assembly. As a result, the Complex I assembly pathway has been redefined in this study. PMID:25887158

  16. (Porphyrinato)bis(phthalocyaninato)dilanthanide(III) complexes presenting a sandwich triple-decker-like structure

    SciTech Connect

    Moussavi, M.; De Cian, A.; Fischer, J.; Weiss, R.

    1986-06-18

    Bis(phthalocyaninato)lanthanide(III) derivatives presenting a sandwich-type structure have been known for many years. These complexes are still intensively studied due to their semi-conductor and electrochromic properties. The synthesis and properties of bis(porphyrinato) and tris(porphyrinato)lanthanide(III) derivatives have also been reported. X-ray structural studies have shown that bis(porphyrinato) complexes have geometries that are similar to those displayed by the LnPc/sub 2/ complexes (Ln = lanthanide; Pc = phthalocyanine) whereas the tris(porphyrinato) derivatives present structures in which two lanthanide(III) metal cations are sandwiched between three macrocyclic rings in triple-decker-like geometry. Structural, magnetic, and spectroscopic properties of the green form of lutetium(III) bis(phthalocyanate) have shown that this complex is in a nonprotonated, one-electron-oxidized ligand form, Ln (Pc/sup 2 -/) (Pc..pi..). In such a molecule, the unpaired spin could be either located on one phthalocyanine ring or delocalized over both rings. In order to force the localization of the unpaired spin on one ring, the authors have tried to synthesize a dissymmetric mixed-ligand, porphyrin (Por) phthalocyanine (Pc), lanthanide sandwich Ln(Por)(Pc). However, under the conditions used, the authors obtained dilanthanide sandwich-triple-decker-like complexes. (Por(Ln)Pc(Ln)Pc) in which the two metal cations are sandwiched between three macrocyclic rings. They report the synthesis and spectral properties of such derivatives obtained with Ln = Nd(III), Eu(III), and Gd(III) and with meso-tetrakis(4-methoxyphenyl) porphyrin (H/sub 2/T(4-OCH/sub 3/)PP) and phthalocyanine (H/sub 2/Pc). The X-ray structure of the neodymim complex is also reported.

  17. Formation of Soluble Organo-Chromium(III) Complexes after Chromate Reduction in the Presence of Cellular Organics

    SciTech Connect

    Puzon, Geoffrey J.; Roberts, Arthur G.; Kramer, David M.; Xun, Luying

    2005-04-01

    Microbial reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] has been investigated as a method for bioremediation of Cr(VI) contaminated environments. The produced Cr(III) is thought to be insoluble Cr(OH)3; however, recent reports suggested a more complex fate of Cr(III). A bacterial enzyme system, using NADH as the reductant, converts Cr(VI) to a soluble NAD+-Cr(III) complex, and cytochrome c-mediated Cr(VI) reduction produces cytochrome c-Cr(III) adducts. In this study, Cr(VI) reduction in the presence of cellular organic metabolites formed both soluble and insoluble organo-Cr(III) end-products. Several soluble end-products were characterized by absorbance spectroscopy and electron paramagnetic resonance spectrometry as organo-Cr(III) complexes, similar to the known ascorbate-Cr(III) complex. The complexes remained soluble and stable upon dialysis against distilled H2O and over a broad pH range. The ready formation of stable organo-Cr(III) complexes suggests that organo-Cr(III) complexes are rather common, likely representing an integral part of the natural cycling of chromium. Finally, thus, organo-Cr(III) complexes may account for the mobile form of Cr(III) detected in the environment.

  18. Octanuclear [Ni(II)₄Ln(III)₄] complexes. Synthesis, crystal structures and magnetocaloric properties.

    PubMed

    Pasatoiu, Traian D; Ghirri, Alberto; Madalan, Augustin M; Affronte, Marco; Andruh, Marius

    2014-06-28

    Two original heterooctanuclear [Ni(II)4Ln(III)4] complexes (Ln(III) = Sm(III), Gd(III)) have been obtained starting from the [Ni(II)(valpn)(H2O)2] mononuclear precursor [H2valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol)] and the corresponding lanthanide nitrates, in the presence of azide anions, through slow capture of atmospheric CO2. Three weak and competitive exchange interactions, J(GdGd), J(GdNi), J(NiNi), make the ground state of this magnetic system degenerate at cryogenic temperature and zero field. This, along with the high spin of Gd(III), lead to a significant magnetocaloric effect spread in the temperature range 1 to 20 K (ΔSm[0-7 T, 3.5 K] = 19 J kg(-1) K(-1)).

  19. Chronic Intermittent Hypoxia Alters Local Respiratory Circuit Function at the Level of the preBötzinger Complex

    PubMed Central

    Garcia, Alfredo J.; Zanella, Sebastien; Dashevskiy, Tatiana; Khan, Shakil A.; Khuu, Maggie A.; Prabhakar, Nanduri R.; Ramirez, Jan-Marino

    2016-01-01

    Chronic intermittent hypoxia (CIH) is a common state experienced in several breathing disorders, including obstructive sleep apnea (OSA) and apneas of prematurity. Unraveling how CIH affects the CNS, and in turn how the CNS contributes to apneas is perhaps the most challenging task. The preBötzinger complex (preBötC) is a pre-motor respiratory network critical for inspiratory rhythm generation. Here, we test the hypothesis that CIH increases irregular output from the isolated preBötC, which can be mitigated by antioxidant treatment. Electrophysiological recordings from brainstem slices revealed that CIH enhanced burst-to-burst irregularity in period and/or amplitude. Irregularities represented a change in individual fidelity among preBötC neurons, and changed transmission from preBötC to the hypoglossal motor nucleus (XIIn), which resulted in increased transmission failure to XIIn. CIH increased the degree of lipid peroxidation in the preBötC and treatment with the antioxidant, 5,10,15,20-Tetrakis (1-methylpyridinium-4-yl)-21H,23H-porphyrin manganese(III) pentachloride (MnTMPyP), reduced CIH-mediated irregularities on the network rhythm and improved transmission of preBötC to the XIIn. These findings suggest that CIH promotes a pro-oxidant state that destabilizes rhythmogenesis originating from the preBötC and changes the local rhythm generating circuit which in turn, can lead to intermittent transmission failure to the XIIn. We propose that these CIH-mediated effects represent a part of the central mechanism that may perpetuate apneas and respiratory instability, which are hallmark traits in several dysautonomic conditions. PMID:26869872

  20. Pentanuclear [2.2] spirocyclic lanthanide(III) complexes: slow magnetic relaxation of the Dy(III) analogue.

    PubMed

    Biswas, Sourav; Das, Sourav; van Leusen, Jan; Kögerler, Paul; Chandrasekhar, Vadapalli

    2015-11-28

    The reaction of LnCl3·6H2O (Ln = Dy(3+), Tb(3+) and Ho(3+)) with the multisite coordinating ligand N'-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylidene)acetohydrazide (LH3) in the presence of pivalic acid (PivH) leads to the formation of three isostructural homometallic pentanuclear complexes, [Dy5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·9·5H2O·5MeOH (1), [Tb5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·10.5H2O·2MeOH·2CHCl3 (2) and [Ho5(LH)4(η(1)-Piv)(η(2)-Piv)3(μ2-η(2)η(1)Piv)2(H2O)]·Cl·14.5H2O·2CHCl3 (3). 1-3 are monocationic and are comprised of four doubly deprotonated [LH](2-) ligands along with six pivalate ions. These complexes possess a [2.2] spirocyclic topology formed by the fusion of two triangles of Ln(III) ions at a common vertex. The magneto chemical analysis reveals the presence of antiferromagnetic exchange interactions at low temperature, and the Dy(III) complex 1 gives an out-of-phase signal with a small curvature in alternating current (ac) magnetic susceptibility measurement. Application of a 3000 G static field during ac measurement intensifies the signals, revealing a second slow relaxation process in the Dy(III) analogue.

  1. Toxic variability and radiation potentiation by Rh(III) complexes in Salmonella typhimurium cells

    SciTech Connect

    Richmond, R.C.; O'Hara, J.; Picker, D.H.; Douple, E.B.

    1986-12-01

    Stationary-phase cells of Salmonella typhimurium were irradiated in phosphate-buffered saline in the presence of rhodium complexes to test for the potentiation of radiation-induced cell killing. Eleven Rh complexes, two Rh(I) and nine Rh(III), were tested. Seven Rh(III) complexes were found to be radiation potentiators; six potentiate only under hypoxic conditions, and one potentiates under both hypoxic and oxic conditions. Four of these seven Rh(III) complexes demonstrate potentiation that is 2 to 13 times greater than the sensitization caused by oxygen. Irradiating cells in Ham's F-12 culture medium rather than in phosphate-buffered saline eliminates this latter hypoxic radiation potentiation. None of the seven Rh(III) radiation potentiators are directly toxic to cells. However, four complexes were tested for hypoxic radiation-induced cytocidal toxicity, and three were found to be toxic after irradiation. The efficiency of this toxicity is not sufficient to account for the observed radiation potentiation. It is suggested that both reductive and oxidative free radical events are involved in the spectrum of Rh(III) potentiation observed.

  2. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand.

    PubMed

    Kanchana Devi, A; Ramesh, R

    2014-01-03

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E=P or As; X=Cl or Br; L=binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx≠gy≠gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (Ru(III)-Ru(III)/Ru(III)-Ru(IV); Ru(III)-Ru(IV)/Ru(IV)-Ru(IV)) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.

  3. Visible-light sensitized luminescent europium(III)-β-diketonate complexes: bioprobes for cellular imaging.

    PubMed

    Reddy, M L P; Divya, V; Pavithran, Rani

    2013-11-21

    Visible-light sensitized luminescent europium(III) molecular materials are of considerable importance because their outstanding photophysical properties make them well suited as labels in fluorescence-based bioassays and low-voltage driven pure red-emitters in optoelectronic technology. One challenge in this field is development of visible-light sensitizing ligands that can form highly emissive europium(III) complexes with sufficient stability and aqueous solubility for practical applications. Indeed, some of the recent reports have demonstrated that the excitation-window can be shifted to longer-wavelengths in europium(III)-β-diketonate complexes by appropriate molecular engineering and suitably expanded π-conjugation in the complex molecules. In this review, attention is focused on the latest innovations in the syntheses and photophysical properties of visible-light sensitized europium(III)-β-diketonate complexes and their application as bioprobes for cellular imaging. Furthermore, luminescent nanomaterials derived from long-wavelength sensitized europium(III)-β-diketonate complexes and their application in life sciences are also highlighted.

  4. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand

    NASA Astrophysics Data System (ADS)

    Kanchana Devi, A.; Ramesh, R.

    2014-01-01

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E = P or As; X = Cl or Br; L = binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx ≠ gy ≠ gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (RuIII-RuIII/RuIII-RuIV; RuIII-RuIV/RuIV-RuIV) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.

  5. Luminescent Iridium(III) Complex Labeled DNA for Graphene Oxide-Based Biosensors.

    PubMed

    Zhao, Qingcheng; Zhou, Yuyang; Li, Yingying; Gu, Wei; Zhang, Qi; Liu, Jian

    2016-02-02

    There has been growing interest in utilizing highly photostable iridium(III) complexes as new luminescent probes for biotechnology and life science. Herein, iridium(III) complex with carboxyl group was synthesized and activated with N-hydroxysuccinimide, followed by tagging to the amino terminate of single-stranded DNA (ssDNA). The Ir-ssDNA probe was further combined with graphene oxide (GO) nanosheets to develop a GO-based biosensor for target ssDNA detection. The quenching efficiency of GO, and the photostability of iridium(III) complex and GO-Ir-ssDNA biosensor, were also investigated. On the basis of the high luminescence quenching efficiency of GO toward iridium(III) complex, the GO-Ir-ssDNA biosensor exhibited minimal background signals, while strong emission was observed when Ir-ssDNA desorbed from GO nanosheets and formed a double helix with the specific target, leading to a high signal-to-background ratio. Moreover, it was found that luminescent intensities of iridium(III) complex and GO-Ir-ssDNA biosensor were around 15 and 3 times higher than those of the traditional carboxyl fluorescein (FAM) dye and the GO-FAM-ssDNA biosensor after UV irradiation, respectively. Our study suggested the sensitive and selective Ir-ssDNA probe was suitable for the development of highly photostable GO-based detection platforms, showing promise for application beyond the OLED (organic light emitting diode) area.

  6. Biological and protein-binding studies of newly synthesized polymer-cobalt(III) complexes.

    PubMed

    Vignesh, G; Pradeep, I; Arunachalam, S; Vignesh, S; Arthur James, R; Arun, R; Premkumar, K

    2016-03-01

    The polymer-cobalt(III) complexes, [Co(bpy)(dien)BPEI]Cl3 · 4H2O (bpy = 2,2'-bipyridine, dien = diethylentriamine, BPEI = branched polyethyleneimine) were synthesized and characterized. The interaction of these complexes with human serum albumin (HSA) and bovine serum albumin (BSA) was investigated under physiological conditions using various physico-chemical techniques. The results reveal that the fluorescence quenching of serum albumins by polymer-cobalt(III) complexes took place through static quenching. The binding of these complexes changed the molecular conformation of the protein considerably. The polymer-cobalt(III) complex with x = 0.365 shows antimicrobial activity against several human pathogens. This complex also induces cytotoxicity against MCF-7 through apoptotic induction. However, further studies are needed to decipher the molecular mode of action of polymer-cobalt(III) complex and for its possible utilization in anticancer therapy. Copyright © 2015 John Wiley & Sons, Ltd.

  7. Pre-Bötzinger complex: Generation and modulation of respiratory rhythm.

    PubMed

    Muñoz-Ortiz, J; Muñoz-Ortiz, E; López-Meraz, M L; Beltran-Parrazal, L; Morgado-Valle, C

    2016-07-18

    In mammals, the preBötzinger complex (preBötC) is a bilateral and symmetrical neural network located in the brainstem which is essential for the generation and modulation of respiratory rhythm. There are few human studies about the preBötC and, its relationship with neurological diseases has not been described. However, the importance of the preBötC in neural control of breathing and its potential participation in neurological diseases in humans, has been suggested based on pharmacological manipulation and lesion of the preBötC in animal models, both in vivo and in vitro. In this review, we describe the effects of some drugs on the inspiratory activity in vitro in a transverse slice that contains the preBötC, as well as some in vivo experiments. Drugs were classified according to their effects on the main neurotransmitter systems and their importance as stimulators or inhibitors of preBötC activity and therefore for the generation of the respiratory rhythm. Clinical neurologists will find this information relevant to understanding how the central nervous system generates the respiratory rhythm and may also relate this information to the findings made in daily practice. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. Honokiol induces superoxide production by targeting mitochondrial respiratory chain complex I in Candida albicans.

    PubMed

    Sun, Lingmei; Liao, Kai; Wang, Dayong

    2017-01-01

    Honokiol, a compound extracted from Magnolia officinalis, has antifungal activities by inducing mitochondrial dysfunction and triggering apoptosis in Candida albicans. However, the mechanism of honokiol-induced oxidative stress is poorly understood. The present investigation was designed to determine the specific mitochondrial reactive oxygen species (ROS)-generation component. We found that honokiol induced mitochondrial ROS accumulation, mainly superoxide anions (O2•-) measured by fluorescent staining method. The mitochondrial respiratory chain complex I (C I) inhibitor rotenone completely blocked O2•- production and provided the protection from the killing action of honokiol. Moreover, respiratory activity and the C I enzyme activity was significantly reduced after honokiol treatment. The differential gene-expression profile also showed that genes involved in oxidoreductase activity, electron transport, and oxidative phosphorylation were upregulated. The present work shows that honokiol may bind to mitochondrial respiratory chain C I, leading to mitochondrial dysfunction, accompanied by increased cellular superoxide anion and oxidative stress. This work not only provides insights on the mechanism by which honokiol interferes with fungal cell, demonstrating previously unknown effects on mitochondrial physiology, but also raises a note of caution on the use of M. officinalis as a Chinese medicine due to the toxic for mitochondria and suggests the possibility of using honokiol as chemosensitizer.

  9. Iron(III) complexing ability of carbohydrate derivatives.

    PubMed

    Ferrari, E; Saladini, M

    2004-06-01

    A solution study on the coordinative ability of galactaric acid (GalAH(2)), d-glucosamine (GlcN) and d-glucosaminic acid (GlcNAH) toward Fe(3+) ion is reported. UV spectroscopic study provides useful information to identify complex species formation and their stability constants are determined by means of potentiometric measurements. GalAH(2) behaves as chelating ligand through carboxylic oxygen and alpha-hydroxylic oxygen in the protonated or dissociated form depending on pH value. Two complex species [Fe(2)GalA(OH)(4)] and Na[FeGalAH(-2)] .2H(2)O are also isolated in the solid state and characterised through IR spectroscopy. GlcNAH also binds the Fe(3+) ion through carboxylic and hydroxylic groups, while NH(2) group is probably involved in metal coordination up to pH 4. GlcN demonstrates low ligating ability at acidic pH and does not prevent metal hydroxyde precipitation.

  10. Auditing of Monitoring and Respiratory Support Equipment in a Level III-C Neonatal Intensive Care Unit

    PubMed Central

    Bergon-Sendin, Elena; Perez-Grande, Carmen; Lora-Pablos, David; De la Cruz Bertolo, Javier; Moral-Pumarega, María Teresa; Bustos-Lozano, Gerardo; Pallas-Alonso, Carmen Rosa

    2015-01-01

    Background. Random safety audits (RSAs) are a safety tool but have not been widely used in hospitals. Objectives. To determine the frequency of proper use of equipment safety mechanisms in relation to monitoring and mechanical ventilation by performing RSAs. The study also determined whether factors related to the patient, time period, or characteristics of the area of admission influenced how the device safety systems were used. Methods. A prospective observational study was conducted in a level III-C Neonatal Intensive Care Unit (NICU) during 2012. 87 days were randomly selected. Appropriate overall use was defined when all evaluated variables were correctly programmed in the audited device. Results. A total of 383 monitor and ventilator audits were performed. The Kappa coefficient of interobserver agreement was 0.93. The rate of appropriate overall use of the monitors and respiratory support equipment was 33.68%. Significant differences were found with improved usage during weekends, OR 1.85 (1.12–3.06, p = 0.01), and during the late shift (3 pm to 10 pm), OR 1.59 (1.03–2.4, p = 0.03). Conclusions. Equipment safety systems of monitors and ventilators are not properly used. To improve patient safety, we should identify which alarms are really needed and where the difficulties lie for the correct alarm programming. PMID:26558277

  11. Auditing of Monitoring and Respiratory Support Equipment in a Level III-C Neonatal Intensive Care Unit.

    PubMed

    Bergon-Sendin, Elena; Perez-Grande, Carmen; Lora-Pablos, David; De la Cruz Bertolo, Javier; Moral-Pumarega, María Teresa; Bustos-Lozano, Gerardo; Pallas-Alonso, Carmen Rosa

    2015-01-01

    Random safety audits (RSAs) are a safety tool but have not been widely used in hospitals. To determine the frequency of proper use of equipment safety mechanisms in relation to monitoring and mechanical ventilation by performing RSAs. The study also determined whether factors related to the patient, time period, or characteristics of the area of admission influenced how the device safety systems were used. A prospective observational study was conducted in a level III-C Neonatal Intensive Care Unit (NICU) during 2012. 87 days were randomly selected. Appropriate overall use was defined when all evaluated variables were correctly programmed in the audited device. A total of 383 monitor and ventilator audits were performed. The Kappa coefficient of interobserver agreement was 0.93. The rate of appropriate overall use of the monitors and respiratory support equipment was 33.68%. Significant differences were found with improved usage during weekends, OR 1.85 (1.12-3.06, p = 0.01), and during the late shift (3 pm to 10 pm), OR 1.59 (1.03-2.4, p = 0.03). Equipment safety systems of monitors and ventilators are not properly used. To improve patient safety, we should identify which alarms are really needed and where the difficulties lie for the correct alarm programming.

  12. NIR-emissive iridium(III) corrole complexes as efficient singlet oxygen sensitizers.

    PubMed

    Sinha, Woormileela; Ravotto, Luca; Ceroni, Paola; Kar, Sanjib

    2015-10-28

    Three new iridium(iii) corrole complexes, having symmetrically and asymmetrically substituted corrole frameworks and judiciously varied axial ligands are prepared and characterized by various spectroscopic techniques including the X-ray structures of two of them. The observed phosphorescence at ambient temperature appears at much longer wavelengths than the previously reported Ir(iii) porphyrin/corrole derivatives. Efficiencies of these compounds in the generation of singlet oxygen are also studied for the first time.

  13. Structure of subcomplex Iβ of mammalian respiratory complex I leads to new supernumerary subunit assignments

    PubMed Central

    Zhu, Jiapeng; King, Martin S.; Yu, Minmin; Klipcan, Liron; Leslie, Andrew G. W.; Hirst, Judy

    2015-01-01

    Mitochondrial complex I (proton-pumping NADH:ubiquinone oxidoreductase) is an essential respiratory enzyme. Mammalian complex I contains 45 subunits: 14 conserved “core” subunits and 31 “supernumerary” subunits. The structure of Bos taurus complex I, determined to 5-Å resolution by electron cryomicroscopy, described the structure of the mammalian core enzyme and allowed the assignment of 14 supernumerary subunits. Here, we describe the 6.8-Å resolution X-ray crystallography structure of subcomplex Iβ, a large portion of the membrane domain of B. taurus complex I that contains two core subunits and a cohort of supernumerary subunits. By comparing the structures and composition of subcomplex Iβ and complex I, supported by comparisons with Yarrowia lipolytica complex I, we propose assignments for eight further supernumerary subunits in the structure. Our new assignments include two CHCH-domain containing subunits that contain disulfide bridges between CX9C motifs; they are processed by the Mia40 oxidative-folding pathway in the intermembrane space and probably stabilize the membrane domain. We also assign subunit B22, an LYR protein, to the matrix face of the membrane domain. We reveal that subunit B22 anchors an acyl carrier protein (ACP) to the complex, replicating the LYR protein–ACP structural module that was identified previously in the hydrophilic domain. Thus, we significantly extend knowledge of how the mammalian supernumerary subunits are arranged around the core enzyme, and provide insights into their roles in biogenesis and regulation. PMID:26371297

  14. Assembly of the Escherichia coli NADH:ubiquinone oxidoreductase (respiratory complex I).

    PubMed

    Friedrich, Thorsten; Dekovic, Doris Kreuzer; Burschel, Sabrina

    2016-03-01

    Energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, couples the electron transfer from NADH to ubiquinone with the translocation of four protons across the membrane. The Escherichia coli complex I is made up of 13 different subunits encoded by the so-called nuo-genes. The electron transfer is catalyzed by nine cofactors, a flavin mononucleotide and eight iron-sulfur (Fe/S)-clusters. The individual subunits and the cofactors have to be assembled together in a coordinated way to guarantee the biogenesis of the active holoenzyme. Only little is known about the assembly of the bacterial complex compared to the mitochondrial one. Due to the presence of so many Fe/S-clusters the assembly of complex I is intimately connected with the systems responsible for the biogenesis of these clusters. In addition, a few other proteins have been reported to be required for an effective assembly of the complex in other bacteria. The proposed role of known bacterial assembly factors is discussed and the information from other bacterial species is used in this review to draw an as complete as possible model of bacterial complex I assembly. In addition, the supramolecular organization of the complex in E. coli is briefly described. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Prof. Conrad Mullineaux.

  15. Spectrophotometric studies of holmium(III) chloride-aluminum(III) chloride vapor complexes

    SciTech Connect

    Williams, C.W.; Hessler, J.P.; Peterson, E.J.

    1980-01-01

    The gas complexation reactions between LnCl/sub 3/ and Al/sub 2/Cl/sub 6/ to yield molecular species of the form LnCl/sub 3/ (Al/sub 2/Cl/sub 6/)/sub x/ have been studied for a number of years. The spectrophotometric technique has been used to deduce the thermodynamic properties of the molecular species. We have studied the HoCl/sub 3/ (Al/sub 2/Cl/sub 6/)/sub x/ system from 600 to 900/sup 0/K and at Al/sub 2/Cl/sub 6/ pressures between 1 and 7 atm. The Ho/sup 3 +/ hypersensitive transition between /sup 5/I/sub 8/ and /sup 5/G/sub 6/ at 456 nm has been used to measure the complex vapor densities as a function of pressure and temperature. A temperature-dependence of the optical absorption spectrum was observed in samples with a constant Ho/sup 3 +/ ion density. These data cannot be understood in terms of the generally used treatment of molar absorptivity, but requires the introduction of an effective oscillator strength. A temperature-dependent oscillator effect is also observed and this is interpeted as evidence for the presence of multiple species with differing oscillator strengths. The consequence of these observations for the determination of equilibrium constants for the different species will be discussed.

  16. PARACEST properties of a dinuclear neodymium(III) complex bound to DNA or carbonate.

    PubMed

    Nwe, Kido; Andolina, Christopher M; Huang, Ching-Hui; Morrow, Janet R

    2009-07-01

    A dinuclear Nd(III) macrocyclic complex of 1 (1,4-bis[1-(4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane]-p-xylene) and mononuclear complexes of 1,4,7-tris-1,4,7,10-tetraazacyclododecane, 2, and 1,4,7-tris[(N-N-diethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane, 3, are prepared. Complexes of 1 and 2 give rise to a PARACEST (paramagnetic chemical exchange saturation transfer) peak from exchangeable amide protons that resonate approximately 12 ppm downfield from the bulk water proton resonance. The dinuclear Nd(III) complex is promising as a PARACEST contrast agent for MRI applications, because it has an optimal pH of 7.5 and the rate constant for amide proton exchange (2700 s(-1)) is nearly as large as it can be within slow exchange conditions with bulk water. Dinuclear Ln(2)(1) complexes (Ln(III) = Nd(III), Eu(III)) bind tightly to anionic ligands including carbonate, diethyl phosphate, and DNA. The CEST amide peak of Nd(2)(1) is enhanced by certain DNA sequences that contain hairpin loops, but decreases in the presence of diethyl phosphate or carbonate. Direct excitation luminescence studies of Eu(2)(1) show that double-stranded and hairpin-loop DNA sequences displace one water ligand on each Eu(III) center. DNA displaces carbonate ion despite the low dissociation constant for the Eu(2)(1) carbonate complex (K(d) = 15 microM). Enhancement of the CEST effect of a lanthanide complex by binding to DNA is a promising step toward the preparation of PARACEST agents containing DNA scaffolds.

  17. PARACEST Properties of a Dinuclear Neodymium(III) Complex Bound to DNA or Carbonate

    PubMed Central

    Nwe, Kido; Andolina, Christopher M.; Huang, Ching-Hui; Morrow, Janet R.

    2009-01-01

    A dinuclear Nd(III) macrocyclic complex of 1 (1,4-bis[1-(4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane]-p-xylene) and mononuclear complexes of 1,4,7-tris-1,4,7,10-tetraazacyclododecane 2, and 1,4,7-tris[(N-N-diethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane, 3, are prepared. Complexes of 1 and 2 give rise to a PARACEST (paramagnetic chemical exchange saturation transfer) peak from exchangeable amide protons that resonate approximately 12 ppm downfield from the bulk water proton resonance. The dinuclear Nd(III) complex is promising as a PARACEST contrast agent for MRI applications because it has an optimal pH of 7.5 and the rate constant for amide proton exchange (2700 s−1) is nearly as large as it can be within slow exchange conditions with bulk water. Dinuclear Ln2(1) complexes (Ln(III) = Nd(III), Eu(III)) bind tightly to anionic ligands including carbonate, diethylphosphate and DNA. The CEST amide peak of Nd2(1) is enhanced by certain DNA sequences that contain hairpin loops, but decreases in the presence of diethyl phosphate or carbonate. Direct excitation luminescence studies of Eu2(1) show that double-stranded and hairpin loop DNA sequences displace one water ligand on each Eu(III) center. DNA displaces carbonate ion despite the low dissociation constant for the Eu2(1) carbonate complex (Kd = 15 µM). Enhancement of the CEST effect of a lanthanide complex by binding to DNA is a promising step toward the preparation of PARACEST agents containing DNA scaffolds. PMID:19555071

  18. Single molecule magnet behaviour in a rare trinuclear {Cr(III)Dy} methoxo-bridged complex.

    PubMed

    Car, Pierre-Emmanuel; Favre, Annaïck; Caneschi, Andrea; Sessoli, Roberta

    2015-09-28

    The reaction of the chromium(iii) chloride tetrahydrofuran complex with the dipivaloylmethane ligand, the lanthanide alcoholic salt DyCl3·CH3OH and the 1,1,1-tris(hydroxymethyl)-ethane ligand resulted in the formation of a new trinuclear chromium-dysprosium complex. Magnetic investigations revealed that the new 3d-4f complex exhibits single molecule magnet behaviour.

  19. Testing the role of preBötzinger Complex somatostatin neurons in respiratory and vocal behaviors.

    PubMed

    Tupal, Srinivasan; Rieger, Michael A; Ling, Guang-Yi; Park, Thomas J; Dougherty, Joseph D; Goodchild, Ann K; Gray, Paul A

    2014-10-01

    Identifying neurons essential for the generation of breathing and related behaviors such as vocalisation is an important question for human health. The targeted loss of preBötzinger Complex (preBötC) glutamatergic neurons, including those that express high levels of somatostatin protein (SST neurons), eliminates normal breathing in adult rats. Whether preBötC SST neurons represent a functionally specialised population is unknown. We tested the effects on respiratory and vocal behaviors of eliminating SST neuron glutamate release by Cre-Lox-mediated genetic ablation of the vesicular glutamate transporter 2 (VGlut2). We found the targeted loss of VGlut2 in SST neurons had no effect on viability in vivo, or on respiratory period or responses to neurokinin 1 or μ-opioid receptor agonists in vitro. We then compared medullary SST peptide expression in mice with that of two species that share extreme respiratory environments but produce either high or low frequency vocalisations. In the Mexican free-tailed bat, SST peptide-expressing neurons extended beyond the preBötC to the caudal pole of the VII motor nucleus. In the naked mole-rat, however, SST-positive neurons were absent from the ventrolateral medulla. We then analysed isolation vocalisations from SST-Cre;VGlut2(F/F) mice and found a significant prolongation of the pauses between syllables during vocalisation but no change in vocalisation number. These data suggest that glutamate release from preBötC SST neurons is not essential for breathing but play a species- and behavior-dependent role in modulating respiratory networks. They further suggest that the neural network generating respiration is capable of extensive plasticity given sufficient time.

  20. [Automated RNA amplification for the rapid identification of Mycobacterium tuberculosis complex in respiratory specimens].

    PubMed

    Drouillon, V; Houriez, F; Buze, M; Lagrange, P; Herrmann, J-L

    2006-01-01

    Rapid and sensitive detection of Mycobacterium tuberculosis complex (MTB) directly on clinical respiratory specimens is essential for a correct management of patients suspected of tuberculosis. For this purpose PCR-based kits are available to detect MTB in respiratory specimen but most of them need at least 4 hours to be completed. New methods, based on TRC method (TRC: Transcription Reverse transcription Concerted--TRCRapid M. Tuberculosis--Tosoh Bioscience, Tokyo, Japon) and dedicated monitor have been developed. A new kit (TRC Rapid M. tuberculosis and Real-time monitor TRCRapid-160, Tosoh Corporation, Japan) enabling one step amplification and real-time detection of MTB 16S rRNA by a combination of intercalative dye oxazole yellow-linked DNA probe and isothermal RNA amplification directly on respiratory specimens has been tested in our laboratory. 319 respiratory specimens were tested in this preliminary study and results were compared to smear and culture. Fourteen had a positive culture for MTB. Among theses samples, smear was positive in 11 cases (78.6%) and TRC process was positive in 8 cases (57.1%). Overall sensitivity of TRC compared to smear positive samples is 73%. Theses first results demonstrated that a rapid identification of MTB was possible (less than 2 processing hours for 14 specimens and about 1 hour for 1 specimen) in most cases of smear positive samples using ready to use reagents for real time detection of MTB rRNA in clinical samples. New pretreatment and extraction reagents kits to increase the stability of the sputum RNA and the extraction efficiency are now tested in our laboratory.

  1. Testing the role of preBötzinger complex somatostatin neurons in respiratory and vocal behaviors

    PubMed Central

    Tupal, Srinivasan; Rieger, Michael A.; Ling, Guang-Yi; Park, Thomas J.; Dougherty, Joseph D.; Goodchild, Ann K.; Gray, Paul A.

    2015-01-01

    Identifying neurons essential for the generation of breathing and related behaviors such as vocalization is an important question for human health. The targeted loss of preBötzinger complex (preBötC) glutamatergic neurons, including those that express high levels of somatostatin protein (SST neurons), eliminates normal breathing in adult rats. Whether preBötC SST neurons represent a functionally specialized population is unknown. We tested the effects on respiratory and vocal behaviors of eliminating SST neuron glutamate release by Cre-Lox-mediated genetic ablation of the vesicular glutamate transporter 2 (VGlut2). We found the targeted loss of VGlut2 in SST neurons had no effect on viability in vivo, or on respiratory period or responses to neurokinin 1 or µ-opioid receptor agonists in vitro. We then compared medullary SST peptide expression in mice with that of two species that share extreme respiratory environments but produce either high or low frequency vocalizations. In the Mexican free-tailed bat, SST peptide-expressing neurons extended beyond the preBötC to the caudal pole of the VII motor nucleus. In the naked mole-rat, however, SST-positive neurons were absent from the ventrolateral medulla. We then analyzed isolation vocalizations from SST-Cre;VGlut2F/F mice and found a significant prolongation of the pauses between syllables during vocalization but no change in vocalization number. These data suggest that glutamate release from preBötC SST neurons is not essential for breathing but play a species- and behavior-dependent role in modulating respiratory networks. They further suggest that the neural network generating respiration is capable of extensive plasticity given sufficient time. PMID:25040660

  2. Synthesis and properties of polynitrophenyltetrazolatocobalt(III) complexes

    SciTech Connect

    Fronabarger, J.; Johnson, R.; Fleming, W.

    1986-01-01

    The explosive 3,5-dinitrophenyltetrazolato complex (3,5-DNP) tends to propagate in the deflagration mode which suggests its use as a pressure cartridge charge. However, the existence of 3,5-DNP as a hydrate appears to result in variations of thermomechanical properties thus rendering it undesirable for component use. The 2,4-DNP and 2,4,6-TNP analogs were synthesized. These exist in the anhydrous form under normal conditions and underwent DDT in component configuration. This negated their use in pressure cartridge applications. Synthetic procedures have been developed for 5-(2,4-dinitrophenyl)tetrazole and 5-picryltetrazole as well as for the precursor 2,4-dinitro- and 2,4,6-trinitrobenzonitriles. 6 refs.

  3. Thermodynamic and Spectroscopic Studies of Lanthanides(III) Complexation with Polyamines in Dimethyl Sulfoxide

    SciTech Connect

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Melchior, Andrea; Portanova, Roberto; Tolazzi, Marilena; Choppin, Gregory R.; Wang, Zheming

    2008-01-01

    The thermodynamic parameters of complexation of Ln(III) cations with tris(2-aminoethyl)amine (tren) and tetraethylenepentamine (tetren) were determined in dimethyl sulfoxide (DMSO) by potentiometry and calorimetry. The excitation and emission spectra and luminescence decay constants of Eu3+ and Tb3+ complexed by tren and tetren, as well as those of the same lanthanides(III) complexed with diethylenetriamine (dien) and triethylenetetramine (trien), were also obtained in the same solvent. The combination of thermodynamic and spectroscopic data showed that, in the 1:1 complexes, all nitrogens of the ligands bound to the lanthanides except in the case of tren, in which only pendant N bound. For the larger ligands (trien, tren, tetren) in the higher complexes (ML2), there was less complete binding by available donors, presumably due to steric crowding. FT-IR studies were carried out in an acetonitrile/DMSO mixture, suitably chosen in order to follow the changes in the primary solvation sphere of lanthanide(III) due to complexation of amine ligands. Results show that the mean number of molecules of DMSO removed from the inner coordination sphere of lanthanides(III) is lower than ligand denticity and that the coordination number of the metal ions increases with amine complexation from ~8 to ~10. Independently of the number and structure of the amines, linear trends, similar for all lanthanides, were obtained by plotting the values of ΔGj°, ΔHj° and TΔSj° for the complexation of ethylenediamine (en), dien, trien, tren and tetren as a function of the number of amine metal-coordinated nitrogen atoms. The main factors on which the thermodynamic functions of lanthanide(III) complexation reactions in DMSO depend are discussed.

  4. Developing polarizable potential for molecular dynamics of Cm(III)-carbonate complexes in liquid water.

    PubMed

    Spezia, Riccardo; Jeanvoine, Yannick; Vuilleumier, Rodolphe

    2014-08-01

    In this work we have developed a polarizable potential to study Cm(III) forming complexes with carbonate anions in liquid water. The potential was developed by employing an extension of the procedure that we used to study the hydration of lanthanoids(III) and actinoids(III). Force field performances were benchmarked against DFT results obtained by both geometry optimization and Car-Parrinello molecular dynamics. With this polarizable potential, we run extended molecular dynamics simulations in liquid water from which we were able to identify structural and dynamical properties of such systems. In particular, water exchange dynamics were analyzed in detail. We obtained an average of three water molecules in the first shell of Cm(III) that show a relatively fast exchange dynamic (faster than for bare ions). Summarizing these results, we were able to draw an analogy to the results from the lanthanoid(III) series. In particular, it seems that Cm(III) behaves more like Nd(III) than Gd(III), as one would expect based on the recent hydration results and on f orbital occupancy.

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

    PubMed

    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.

  6. Cellulose derivatives modified by sodium tellurate and a chromium(III) tellurate complex.

    PubMed

    Butler, Ian S; El-Sherbeny, Heba Allah M; Kenawy, Ibrahim; Mostafa, Sahar I

    2016-07-01

    A novel cellulose (Cell) derivative, sodium-tellurato (Cell-TeO(OH)4(ONa)/Cell-Cl), has been synthesized from the reaction of 6-chloro-6-deoxycellulose (Cell-Cl) with telluric acid in the presence of sodium hydroxide. The subsequent reaction of this polymeric material with chromium(III) in aqueous solution yields the [Cr(Cell-TeO3(OH)3/Cell-Cl)(Cell-TeO2(OH)4/Cell-Cl)(H2O)3] complex. The molecular structures and morphology of the new polymer and the Cr(III) complex have been examined using elemental analysis, solid-state (13)C NMR, UV-vis, XRD and FTIR spectroscopy, and SEM-EDX, TGA and magnetic measurements. The results are considered to be consistent with the formulations proposed. The deprotonation constants of the modified cellulose and the stability constant of the Cr(III) complex have been determined by pH-metric measurements.

  7. Kinetics of the reduction of cobalt(III) amine complexes by 1-hydroxy-1-methylethyl radicals

    SciTech Connect

    Kusaba, K.; Ogino, Hiroshi ); Bakac, A.; Espenon, J.H. )

    1989-03-08

    In order to better understand the rate constants for the reduction of several cobalt complexes by 1-hydroxy-1-methylene radicals ({sup {sm bullet}}C(CH{sub 3}){sub 2}OH), the reactions of {sup {sm bullet}}(CH{sub 3}){sub 2}OH with several cobalt(III) complexes of bidentate amines have been studied. The Marcus-Hush theory was deemed the most appropriate for analysis of the kinetic data. The correlation between the kinetics of the reduction of the Co(III) amines by C(CH{sub 3}){sub 2}OH and the reduction of the first d-d band for Co(III) complexes is discussed. 21 refs., 2 figs., 1 tab.

  8. Mitochondrial Complex I Activity is Conditioned by Supercomplex I-III2-IV Assembly in Brain Cells: Relevance for Parkinson's Disease.

    PubMed

    Lopez-Fabuel, Irene; Resch-Beusher, Monica; Carabias-Carrasco, Monica; Almeida, Angeles; Bolaños, Juan P

    2017-02-14

    The assembly of complex I (CI) with complexes III (CIII) and IV (CIV) of the mitochondrial respiratory chain (MRC) to configure I-III- or I-III-IV-containing supercomplexes (SCs) regulates mitochondrial energy efficiency and reactive oxygen species (mROS) production. However, whether the occurrence of SCs impacts on CI specific activity remains unknown to our knowledge. To investigate this issue, here we determined CI activity in primary neurons and astrocytes, cultured under identical antioxidants-free medium, from two mouse strains (C57Bl/6 and CBA) and Wistar rat, i.e. three rodent species with or without the ability to assemble CIV into SCs. We found that CI activity was 6- or 1.8-fold higher in astrocytes than in neurons, respectively, from rat or CBA mouse, which can form I-III2-IV SC; however, CI activity was similar in the cells from C57Bl/6 mouse, which does not form I-III2-IV SC. Interestingly, CII-III activity, which was comparable in neurons and astrocytes from mice, was about 50% lower in astrocytes when compared with neurons from rat, a difference that was abolished by antioxidants- or serum-containing media. CIV and citrate synthase activities were similar under all conditions studied. Interestingly, in rat astrocytes, CI abundance in I-III2-IV SC was negligible when compared with its abundance in I-III-containing SCs. Thus, CIV-containing SCs formation may determine CI specific activity in astrocytes, which is important to understand the mechanism for CI deficiency observed in Parkinson's disease.

  9. Studies on chemistry, spectroscopy and antioxidant activities of chromium(III)-hydrazide complexes.

    PubMed

    Shamshad, Bushra; Jamal, Rifat A; Ashiq, Uzma; Mahrooof-Tahir, Mohammad; Shaikh, Zara; Sultan, Sadaf; Khan, Khalid M

    2015-01-01

    Acid hydrazides are vital chemical entities due to their biological activities. Upon complexation with certain metal ions, their biological activities are known to be positively enhanced. The present work describes the synthesis of Cr(III)-hydrazide complexes, and their structural, spectroscopic and antioxidant properties to reveal their chemistry and biochemistry. Physical (magnetic moment, conductivity measurements), analytical (C, H, N and Cr analysis) and spectral (EI-Mass, FTIR) techniques are used for the characterization of synthesized compounds. All Cr(III)-hydrazide complexes exhibit octahedral geometry with general formula [Cr(L)2(H2O)2]Cl3. In these complexes, the hydrazide ligands are coordinated via carbonyl oxygen and terminal amino nitrogen in a bidentate fashion. All Cr(III)-hydrazide complexes were screened for in vitro diphenyldipicryl hydrazine (DPPH), superoxide dismutase and nitric oxide radical scavenging activities. Majority of the Cr(III)-hydrazide complexes were found to be more potent scavengers than their uncoordinated hydrazide ligands. This study demonstrates an interesting structure-activity relationship (SAR) which is presented here.

  10. One severe acute respiratory syndrome coronavirus protein complex integrates processive RNA polymerase and exonuclease activities.

    PubMed

    Subissi, Lorenzo; Posthuma, Clara C; Collet, Axelle; Zevenhoven-Dobbe, Jessika C; Gorbalenya, Alexander E; Decroly, Etienne; Snijder, Eric J; Canard, Bruno; Imbert, Isabelle

    2014-09-16

    In addition to members causing milder human infections, the Coronaviridae family includes potentially lethal zoonotic agents causing severe acute respiratory syndrome (SARS) and the recently emerged Middle East respiratory syndrome. The ∼30-kb positive-stranded RNA genome of coronaviruses encodes a replication/transcription machinery that is unusually complex and composed of 16 nonstructural proteins (nsps). SARS-CoV nsp12, the canonical RNA-dependent RNA polymerase (RdRp), exhibits poorly processive RNA synthesis in vitro, at odds with the efficient replication of a very large RNA genome in vivo. Here, we report that SARS-CoV nsp7 and nsp8 activate and confer processivity to the RNA-synthesizing activity of nsp12. Using biochemical assays and reverse genetics, the importance of conserved nsp7 and nsp8 residues was probed. Whereas several nsp7 mutations affected virus replication to a limited extent, the replacement of two nsp8 residues (P183 and R190) essential for interaction with nsp12 and a third (K58) critical for the interaction of the polymerase complex with RNA were all lethal to the virus. Without a loss of processivity, the nsp7/nsp8/nsp12 complex can associate with nsp14, a bifunctional enzyme bearing 3'-5' exoribonuclease and RNA cap N7-guanine methyltransferase activities involved in replication fidelity and 5'-RNA capping, respectively. The identification of this tripartite polymerase complex that in turn associates with the nsp14 proofreading enzyme sheds light on how coronaviruses assemble an RNA-synthesizing machinery to replicate the largest known RNA genomes. This protein complex is a fascinating example of the functional integration of RNA polymerase, capping, and proofreading activities.

  11. One severe acute respiratory syndrome coronavirus protein complex integrates processive RNA polymerase and exonuclease activities

    PubMed Central

    Subissi, Lorenzo; Posthuma, Clara C.; Collet, Axelle; Zevenhoven-Dobbe, Jessika C.; Gorbalenya, Alexander E.; Decroly, Etienne; Snijder, Eric J.; Canard, Bruno; Imbert, Isabelle

    2014-01-01

    In addition to members causing milder human infections, the Coronaviridae family includes potentially lethal zoonotic agents causing severe acute respiratory syndrome (SARS) and the recently emerged Middle East respiratory syndrome. The ∼30-kb positive-stranded RNA genome of coronaviruses encodes a replication/transcription machinery that is unusually complex and composed of 16 nonstructural proteins (nsps). SARS-CoV nsp12, the canonical RNA-dependent RNA polymerase (RdRp), exhibits poorly processive RNA synthesis in vitro, at odds with the efficient replication of a very large RNA genome in vivo. Here, we report that SARS-CoV nsp7 and nsp8 activate and confer processivity to the RNA-synthesizing activity of nsp12. Using biochemical assays and reverse genetics, the importance of conserved nsp7 and nsp8 residues was probed. Whereas several nsp7 mutations affected virus replication to a limited extent, the replacement of two nsp8 residues (P183 and R190) essential for interaction with nsp12 and a third (K58) critical for the interaction of the polymerase complex with RNA were all lethal to the virus. Without a loss of processivity, the nsp7/nsp8/nsp12 complex can associate with nsp14, a bifunctional enzyme bearing 3′-5′ exoribonuclease and RNA cap N7-guanine methyltransferase activities involved in replication fidelity and 5′-RNA capping, respectively. The identification of this tripartite polymerase complex that in turn associates with the nsp14 proofreading enzyme sheds light on how coronaviruses assemble an RNA-synthesizing machinery to replicate the largest known RNA genomes. This protein complex is a fascinating example of the functional integration of RNA polymerase, capping, and proofreading activities. PMID:25197083

  12. Cyclometalated Iridium(III) Imidazole Phenanthroline Complexes as Luminescent and Electrochemiluminescent G-Quadruplex DNA Binders.

    PubMed

    Castor, Katherine J; Metera, Kimberly L; Tefashe, Ushula M; Serpell, Christopher J; Mauzeroll, Janine; Sleiman, Hanadi F

    2015-07-20

    Six cyclometalated iridium(III) phenanthroimidazole complexes with different modifications to the imidazole phenanthroline ligand exhibit enhanced luminescence when bound to guanine (G-) quadruplex DNA sequences. The complexes bind with low micromolar affinity to human telomeric and c-myc sequences in a 1:1 complex:quadruplex stoichiometry. Due to the luminescence enhancement upon binding to G-quadruplex DNA, the complexes can be used as selective quadruplex indicators. In addition, the electrogenerated chemiluminescence of all complexes increases in the presence of specific G-quadruplex sequences, demonstrating potential for the development of an ECL-based G-quadruplex assay.

  13. Genome Analysis of Structure–Function Relationships in Respiratory Complex I, an Ancient Bioenergetic Enzyme

    PubMed Central

    Degli Esposti, Mauro

    2016-01-01

    Respiratory complex I (NADH:ubiquinone oxidoreductase) is a ubiquitous bioenergetic enzyme formed by over 40 subunits in eukaryotes and a minimum of 11 subunits in bacteria. Recently, crystal structures have greatly advanced our knowledge of complex I but have not clarified the details of its reaction with ubiquinone (Q). This reaction is essential for bioenergy production and takes place in a large cavity embedded within a conserved module that is homologous to the catalytic core of Ni–Fe hydrogenases. However, how a hydrogenase core has evolved into the protonmotive Q reductase module of complex I has remained unclear. This work has exploited the abundant genomic information that is currently available to deduce structure–function relationships in complex I that indicate the evolutionary steps of Q reactivity and its adaptation to natural Q substrates. The results provide answers to fundamental questions regarding various aspects of complex I reaction with Q and help re-defining the old concept that this reaction may involve two Q or inhibitor sites. The re-definition leads to a simplified classification of the plethora of complex I inhibitors while throwing a new light on the evolution of the enzyme function. PMID:26615219

  14. The multitude of iron-sulfur clusters in respiratory complex I.

    PubMed

    Gnandt, Emmanuel; Dörner, Katerina; Strampraad, Marc F J; de Vries, Simon; Friedrich, Thorsten

    2016-08-01

    Respiratory complex I couples the electron transfer from NADH to ubiquinone with the translocation of protons across the membrane. Complex I contains one non-covalently bound flavin mononucleotide and, depending on the species, up to ten iron-sulfur (Fe/S) clusters as cofactors. The reason for the presence of the multitude of Fe/S clusters in complex I remained enigmatic for a long time. The question was partly answered by investigations on the evolution of the complex revealing the stepwise construction of the electron transfer domain from several modules. Extension of the ancestral to the modern electron input domain was associated with the acquisition of several Fe/S-proteins. The X-ray structure of the complex showed that the NADH oxidation-site is connected with the quinone-reduction site by a chain of seven Fe/S-clusters. Fast enzyme kinetics revealed that this chain of Fe/S-clusters is used to regulate electron-tunneling rates within the complex. A possible function of the off-pathway cluster N1a is discussed. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

  15. RNA-activated DNA cleavage by the Type III-B CRISPR–Cas effector complex

    PubMed Central

    Estrella, Michael A.; Kuo, Fang-Ting; Bailey, Scott

    2016-01-01

    The CRISPR (clustered regularly interspaced short palindromic repeat) system is an RNA-guided immune system that protects prokaryotes from invading genetic elements. This system represents an inheritable and adaptable immune system that is mediated by multisubunit effector complexes. In the Type III-B system, the Cmr effector complex has been found to cleave ssRNA in vitro. However, in vivo, it has been implicated in transcription-dependent DNA targeting. We show here that the Cmr complex from Thermotoga maritima can cleave an ssRNA target that is complementary to the CRISPR RNA. We also show that binding of a complementary ssRNA target activates an ssDNA-specific nuclease activity in the histidine–aspartate (HD) domain of the Cmr2 subunit of the complex. These data suggest a mechanism for transcription-coupled DNA targeting by the Cmr complex and provide a unifying mechanism for all Type III systems. PMID:26848046

  16. Cyanido-Bridged {Ln(III)W(V)} Heterobinuclear Complexes: Synthesis and Magneto-Structural Study.

    PubMed

    Alexandru, Maria-Gabriela; Visinescu, Diana; Shova, Sergiu; Lloret, Francesc; Julve, Miguel

    2017-09-27

    A new series of cyanido-bridged {Ln(III)W(V)} heterobinuclear complexes of formula [Ln(III)(pyim)2(i-PrOH)(H2O)2(μ-CN)W(V)(CN)7]·2H2O [Ln = Gd (1), Tb (2), Dy (3), Ho (4), and Er (5); pyim = 2-(1H-imidazol-2-yl)-pyridine) and i-PrOH = isopropyl alcohol] were synthesized by one-pot reaction between (NH3Bu)3[W(CN)8] and [Ln(pyim)2](2+) complexes (generated in situ by mixing the corresponding Ln(III) ions and the pyim ligand). Compounds 1-5 are isomorphous and crystallize in the monoclinic system P21/n space group. Their crystal structure consists of binuclear units in which the octacyanotungstate(V) anion coordinates to the corresponding Ln(III) ion through a single cyanide ligand. The tungsten(V) and lanthanide(III) ions are eight-coordinated, in distorted square antiprism (W(V)) and distorted trigonal dodecahedron (Ln(III)) geometries, respectively. The direct-current (dc) magnetic properties for 1-5 reveal the occurrence of weak antiferromagnetic interactions between W(V) and Ln(III) cation, with (8)S7/2, (7)F6, (6)H15/2, (5)I8, and (4)I15/2 as ground terms for Gd(III), Tb(III), Dy(III) Ho(III), and Er(III), respectively [JWLn = -1.19(1) (1), -1.02(2) (2), -1.10(2) (3), -1.30(2) (4), and -1.50(3) cm(-1) (5), the spin Hamiltonian being defined as H = -JWLn SW·SLn]. The fit of the χMT data of 2-4 points out a positive value for the energy gap between the ML components (Δ). This feature is corroborated by their Q-band electron paramagnetic resonance spectra at low temperature, which clearly show MJ = 0 (2 and 4) and ±1/2 (3 and 5). Incipient frequency-dependent alternating-current magnetic susceptibility signals are observed for 3 and 5 under applied dc fields supporting the presence of slow magnetic relaxation behavior, the blocking temperatures being below 2.0 K. This new series of {Ln(III)W(V)} heterobinuclear compounds provides more insights into the exchange magnetic interaction between 5d and 4f centers via the cyanide-bridge, for which scarce information

  17. An Iridium(III) Complex Inhibits JMJD2 Activities and Acts as a Potential Epigenetic Modulator.

    PubMed

    Liu, Li-Juan; Lu, Lihua; Zhong, Hai-Jing; He, Bingyong; Kwong, Daniel W J; Ma, Dik-Lung; Leung, Chung-Hang

    2015-08-27

    A novel iridium(III) complex was synthesized and evaluated for its ability to target JMJD2 enzymatic activity. The iridium(III) complex 1 can inhibit JMJD2 activity and was selective for JMJD2 activity over JARID, JMJD3, and HDAC activities. Moreover, 1 suppressed the trimethylation of the p21 promoter on H3K9me3 and interrupted the JMJD2D-H3K9me3 interactions in human cells, suggesting that it could act as an epigenetic modulator. To our knowledge, 1 represents the first metal-based JMJD2 inhibitor reported in the literature.

  18. Stoichiometry of proton translocation by respiratory complex I and its mechanistic implications

    PubMed Central

    Wikström, Mårten; Hummer, Gerhard

    2012-01-01

    Complex I (NADH-ubiquinone oxidoreductase) in the respiratory chain of mitochondria and several bacteria functions as a redox-driven proton pump that contributes to the generation of the protonmotive force across the inner mitochondrial or bacterial membrane and thus to the aerobic synthesis of ATP. The stoichiometry of proton translocation is thought to be 4 H+ per NADH oxidized (2 e-). Here we show that a H+/2 e- ratio of 3 appears more likely on the basis of the recently determined H+/ATP ratio of the mitochondrial F1Fo-ATP synthase of animal mitochondria and of a set of carefully determined ATP/2 e- ratios for different segments of the mitochondrial respiratory chain. This lower H+/2 e- ratio of 3 is independently supported by thermodynamic analyses of experiments with both mitochondria and submitochondrial particles. A reduced H+/2 e- stoichiometry of 3 has important mechanistic implications for this proton pump. In a rough mechanistic model, we suggest a concerted proton translocation mechanism in the three homologous and tightly packed antiporter-like subunits L, M, and N of the proton-translocating membrane domain of complex I. PMID:22392981

  19. Luminescent dendritic cyclometalated iridium(III) polypyridine complexes: synthesis, emission behavior, and biological properties.

    PubMed

    Zhang, Kenneth Yin; Liu, Hua-Wei; Fong, Tommy Tsz-Him; Chen, Xian-Guang; Lo, Kenneth Kam-Wing

    2010-06-21

    Luminescent dendritic cyclometalated iridium(III) polypyridine complexes [{Ir(N--C)(2)}(n)(bpy-n)](PF(6))(n) (HN--C = 2-phenylpyridine, Hppy, n = 8 (ppy-8), 4 (ppy-4), 3 (ppy-3); HN--C = 2-phenylquinoline, Hpq, n = 8 (pq-8), 4 (pq-4), 3 (pq-3)) have been designed and synthesized. The properties of these dendrimers have been compared to those of their monomeric counterparts [Ir(N--C)(2)(bpy-1)](PF(6)) (HN--C = Hppy (ppy-1), Hpq (pq-1)). Cyclic voltammetric studies revealed that the iridium(IV/III) oxidation and bpy-based reduction occurred at about +1.24 to +1.29 V and -1.21 to -1.27 V versus SCE, respectively, for all the complexes. The molar absorptivity of the dendritic iridium(III) complexes is approximately proportional to the number of [Ir(N--C)(2)(N--N)] moieties in one complex molecule. However, the emission lifetimes and quantum yields are relatively independent of the number of [Ir(N--C)(2)(N--N)] units, suggesting negligible electronic communications between these units. Upon photoexcitation, the complexes displayed triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ir) --> pi*(bpy-n)) emission. The interaction of these complexes with plasmid DNA has been investigated by agarose gel retardation assays. The results showed that the dendritic iridium(III) complexes, unlike their monomeric counterparts, bound to the plasmid, and the interaction was electrostatic in nature. The lipophilicity of all the complexes has been determined by reversed-phase high-performance liquid chromatography (HPLC). Additionally, the cellular uptake of the complexes by the human cervix epithelioid carcinoma (HeLa) cell line has been examined by inductively coupled plasma mass spectrometry (ICP-MS), laser-scanning confocal microscopy, and flow cytometry. Upon internalization, all the complexes were localized in the perinuclear region, forming very sharp luminescent rings surrounding the nuclei. Interestingly, in addition to these rings, HeLa cells treated with the dendritic

  20. The globular cluster system of NGC 1316. III. Kinematic complexity

    NASA Astrophysics Data System (ADS)

    Richtler, T.; Hilker, M.; Kumar, B.; Bassino, L. P.; Gómez, M.; Dirsch, B.

    2014-09-01

    discernable out to 3' radius. The kinematic major axis of NGC 1316 is misaligned by about 10° with the photometric major axis, which might indicate a triaxial symmetry. A simple spherical model like that suggested by dynamical analyses of planetary nebulae also reproduces the velocity dispersions of the faint globular clusters. Conclusions: The central dark matter density of the present model resembles a giant elliptical galaxy. This contradicts population properties which indicate spiral galaxies as pre-merger components. Modified Newtonian dynamics (MOND) would provide a solution, but the kinematical complexity of NGC 1316 does not allow a really firm conclusion. However, NGC 1316 might anyway be a problem for a cold dark matter scenario, if the high dark matter density in the inner region is confirmed in future studies. Based on observations obtained with the VLT at ESO, Cerro Paranal, Chile under the programme 078.B-0856.Appendices are available in electronic form at http://www.aanda.org

  1. Ester-Modified Cyclometalated Iridium(III) Complexes as Mitochondria-Targeting Anticancer Agents

    PubMed Central

    Wang, Fang-Xin; Chen, Mu-He; Hu, Xiao-Ying; Ye, Rui-Rong; Tan, Cai-Ping; Ji, Liang-Nian; Mao, Zong-Wan

    2016-01-01

    Organometallic iridium complexes are potent anticancer candidates which act through different mechanisms from cisplatin-based chemotherapy regimens. Here, ten phosphorescent cyclometalated iridium(III) complexes containing 2,2′-bipyridine-4,4′-dicarboxylic acid and its diester derivatives as ligands are designed and synthesized. The modification by ester group, which can be hydrolysed by esterase, facilitates the adjustment of drug-like properties. The quantum yields and emission lifetimes are influenced by variation of the ester substituents on the Ir(III) complexes. The cytotoxicity of these Ir(III) complexes is correlated with the length of their ester groups. Among them, 4a and 4b are found to be highly active against a panel of cancer cells screened, including cisplatin-resistant cancer cells. Mechanism studies in vitro indicate that they undergo hydrolysis of ester bonds, accumulate in mitochondria, and induce a series of cell-death related events mediated by mitochondria. Furthermore, 4a and 4b can induce pro-death autophagy and apoptosis simultaneously. Our study indicates that ester modification is a simple and feasible strategy to enhance the anticancer potency of Ir(III) complexes. PMID:27958338

  2. Reactive oxygen species production induced by pore opening in cardiac mitochondria: The role of complex III.

    PubMed

    Korge, Paavo; Calmettes, Guillaume; John, Scott A; Weiss, James N

    2017-06-16

    Recent evidence has implicated succinate-driven reverse electron transport (RET) through complex I as a major source of damaging reactive oxygen species (ROS) underlying reperfusion injury after prolonged cardiac ischemia. However, this explanation may be incomplete, because RET on reperfusion is self-limiting and therefore transient. RET can only generate ROS when mitochondria are well polarized, and it ceases when permeability transition pores (PTP) open during reperfusion. Because prolonged ischemia/reperfusion also damages electron transport complexes, we investigated whether such damage could lead to ROS production after PTP opening has occurred. Using isolated cardiac mitochondria, we demonstrate a novel mechanism by which antimycin-inhibited complex III generates significant amounts of ROS in the presence of Mg(2+) and NAD(+) and the absence of exogenous substrates upon inner membrane pore formation by alamethicin or Ca(2+)-induced PTP opening. We show that H2O2 production under these conditions is related to Mg(2+)-dependent NADH generation by malic enzyme. H2O2 production is blocked by stigmatellin, indicating its origin from complex III, and by piericidin, demonstrating the importance of NADH-related ubiquinone reduction for ROS production under these conditions. For maximal ROS production, the rate of NADH generation has to be equal or below that of NADH oxidation, as further increases in [NADH] elevate ubiquinol-related complex III reduction beyond the optimal range for ROS generation. These results suggest that if complex III is damaged during ischemia, PTP opening may result in succinate/malate-fueled ROS production from complex III due to activation of malic enzyme by increases in matrix [Mg(2+)], [NAD(+)], and [ADP]. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Reactivity of a Cobalt(III)–Hydroperoxo Complex in Electrophilic Reactions

    SciTech Connect

    Shin, Bongki; Sutherlin, Kyle D.; Ohta, Takehiro; Ogura, Takashi; Solomon, Edward I.; Cho, Jaeheung

    2016-11-15

    The reactivity of mononuclear metal-hydroperoxo adducts has fascinated researchers in many areas due to their diverse biological and catalytic processes. In this study, a mononuclear cobalt(III)-peroxo complex bearing a tetradentate macrocyclic ligand, [CoIII(Me3-TPADP)(O2)]+ (Me3-TPADP = 3,6,9-trimethyl-3,6,9-triaza-1(2,6)-pyridinacyclodecaphane), was prepared by reacting [CoII(Me3-TPADP)(CH3CN)2]2+ with H2O2 in the presence of triethylamine. Upon protonation, the cobalt(III)- peroxo intermediate was converted into a cobalt(III)-hydroperoxo complex, [CoIII(Me3-TPADP)(O2H)(CH3CN)]2+. The mononuclear cobalt(III)-peroxo and -hydroperoxo intermediates were characterized by a variety of physicochemical methods. Results of electrospray ionization mass spectrometry clearly show the transformation of the intermediates: the peak at m/z 339.2 assignable to the cobalt(III)-peroxo species disappears with concomitant growth of the peak at m/z 190.7 corresponding to the cobalt(III)-hydroperoxo complex (with bound CH3CN). Isotope labeling experiments further support the existence of the cobalt(III)-peroxo and -hydroperoxo complexes. In particular, the O-O bond stretching frequency of the cobalt(III)-hydroperoxo complex was determined to be 851 cm-1 for 16O2H samples (803 cm-1 for 18O2H samples) and its Co-O vibrational energy was observed at 571 cm-1 for 16O2H samples (551 cm-1 for 18O2H samples; 568 cm-1 for 16O2 2H samples) by resonance Raman spectroscopy. Reactivity studies performed with the cobalt(III)-peroxo and -hydroperoxo complexes in organic functionalizations reveal that the latter is capable of

  4. Lanthanide(III)/actinide(III) differentiation in coordination of azine molecules to tris(cyclopentadienyl) complexes of cerium and uranium.

    PubMed

    Mehdoui, Thouraya; Berthet, Jean-Claude; Thuéry, Pierre; Ephritikhine, Michel

    2004-02-21

    Reaction of azine molecules L with the trivalent metallocenes [M(C5H4R)3](M = Ce, U; R = But, SiMe3) in toluene gave the Lewis base adducts [M(C5H4R)3(L)](L = pyridine, 3-picoline, 3,5-lutidine, 3-chloropyridine, pyridazine, pyrimidine, pyrazine, 3,5-dimethylpyrazine and s-triazine), except in the cases of M = U and L = 3-chloropyridine, pyridazine, pyrazine and s-triazine where oxidation of U(III) was found to occur. In the pairs of analogous compounds of Ce(III) and U(III), i.e.[M(C5H4But)3(L)](L = pyridine, picoline) and [M(C5H4SiMe3)3(L)](L = pyridine, lutidine, pyrimidine and dimethylpyrazine), the M-N and average M-C distances are longer for M = Ce than for M = U; however, within a series of azine adducts of the same metallocene, no significant variation is noted in the M-N and average M-C distances. The equilibria between [M(C5H4R)3], L and [M(C5H4R)3(L)] were studied by 1H NMR spectroscopy. The stability constants of the uranium complexes, KUL, are greater than those of the cerium counterparts, KCeL. The values of KML are much greater for R = SiMe3 than for R = But and a linear correlation is found between the logarithms of KML and the hydrogen-bond basicity pKHB scale of the azines. Thermodynamic parameters indicate that the enthalpy-entropy compensation effect holds for these complexation reactions. Competition reactions of [Ce(C5H4R)3] and [U(C5H4R)3] with L show that the selectivity of L in favour of U(III) increases with the [small pi] donor character of the metallocene and is proportional to the pi accepting ability of the azine molecule, measured by its reduction potential.

  5. Molecular structure and biological studies on Cr(III), Mn(II) and Fe(III) complexes of heterocyclic carbohydrazone ligand

    NASA Astrophysics Data System (ADS)

    Abu El-Reash, G. M.; El-Gammal, O. A.; Radwan, A. H.

    2014-03-01

    The chelating behavior of the ligand (H2APC) based on carbohydrazone core modified with pyridine end towards Cr(III), Mn(II) and Fe(III) ions have been examined. The 1H NMR and IR data for H2APC revealed the presence of two stereoisomers syn and anti in both solid state and in solution in addition to the tautomeric versatility based on the flexible nature of the hydrazone linkage leading to varied coordination modes. The spectroscopic data confirmed that the ligand behaves as a monobasic tridentate in Cr(III) and Fe(III) complexes and as neutral tetradentate in Mn(II) complex. The electronic spectra as well as the magnetic measurements confirmed the octahedral geometry for all complexes. The bond length and angles were evaluated by DFT method using material studio program for all complexes. The thermal behavior and the kinetic parameters of degradation were determined using Coats-Redfern and Horowitz-Metzger methods. The antioxidant (DDPH and ABTS methods), anti-hemolytic and cytotoxic activities of the compounds have been screened. Cr(III) complex and H2APC showed the highest antioxidant activity using ABTS and DPPH methods. With respect to in vitro Ehrlich ascites assay, H2APC exhibited the potent activity followed by Fe(III) and Cr(III)complexes.

  6. Imaging RNA polymerase III transcription using a photostable RNA-fluorophore complex.

    PubMed

    Song, Wenjiao; Filonov, Grigory S; Kim, Hyaeyeong; Hirsch, Markus; Li, Xing; Moon, Jared D; Jaffrey, Samie R

    2017-09-25

    Quantitative measurement of transcription rates in live cells is important for revealing mechanisms of transcriptional regulation. This is particularly challenging when measuring the activity of RNA polymerase III (Pol III), which transcribes growth-promoting small RNAs. To address this issue, we developed Corn, a genetically encoded fluorescent RNA reporter suitable for quantifying RNA transcription in cells. Corn binds and induces fluorescence of 3,5-difluoro-4-hydroxybenzylidene-imidazolinone-2-oxime, which resembles the fluorophore found in red fluorescent protein (RFP). Notably, Corn shows high photostability, enabling quantitative fluorescence imaging of mTOR-dependent Pol III transcription. We found that, unlike actinomycin D, mTOR inhibitors resulted in heterogeneous transcription suppression in individual cells. Quantitative imaging of Corn-tagged Pol III transcript levels revealed distinct Pol III transcription 'trajectories' elicited by mTOR inhibition. Together, these studies provide an approach for quantitative measurement of Pol III transcription by direct imaging of Pol III transcripts containing a photostable RNA-fluorophore complex.

  7. Structures of restriction endonuclease HindIII in complex with its cognate DNA and divalent cations.

    PubMed

    Watanabe, Nobuhisa; Takasaki, Yozo; Sato, Chika; Ando, Shoji; Tanaka, Isao

    2009-12-01

    The three-dimensional crystal structures of HindIII bound to its cognate DNA with and without divalent cations were solved at 2.17 and 2.00 A resolution, respectively. HindIII forms a dimer. The structures showed that HindIII belongs to the EcoRI-like (alpha-class) subfamily of type II restriction endonucleases. The cognate DNA-complex structures revealed the specific DNA-recognition mechanism of HindIII by which it recognizes the palindromic sequence A/AGCTT. In the Mg(2+) ion-soaked structure the DNA was cleaved and two ions were bound at each active site, corresponding to the two-metal-ion mechanism.

  8. An EXAFS spectroscopic study of Am(III) complexation with lactate.

    PubMed

    Fröhlich, Daniel R; Skerencak-Frech, Andrej; Kaplan, Ugras; Koke, Carsten; Rossberg, André; Panak, Petra J

    2015-11-01

    The pH dependence (1-7) of Am(III) complexation with lactate in aqueous solution is studied using extended X-ray absorption fine-structure (EXAFS) spectroscopy. Structural data (coordination numbers, Am--O and Am--C distances) of the formed Am(III)-lactate species are determined from the raw k(3)-weighted Am LIII-edge EXAFS spectra. Between pH 1 and pH 6, Am(III) speciation shifts continuously towards complexed species with increasing pH. At higher pH, the amount of complexed species decreases due to formation of hydroxo species. The coordination numbers and distances (3.41-3.43 Å) of the coordinating carbon atoms clearly point out that lactate is bound `side-on' to Am(III) through both the carboxylic and the α-hydroxy function of lactate. The experimentally determined coordination numbers are compared with speciation calculations on the basis of tabulated thermodynamic stability constants. Both EXAFS data and thermodynamic modelling are in very good agreement. The EXAFS spectra are also analyzed by iterative transformation factor analysis to further verify the determined Am(III) speciation and the used structural model.

  9. Three-Coordinate Terminal Imidoiron(III) Complexes: Structure, Spectroscopy, and Mechanism of Formation

    PubMed Central

    Cowley, Ryan E.; DeYonker, Nathan J.; Eckert, Nathan A.; Cundari, Thomas R.; DeBeer, Serena; Bill, Eckhard; Ottenwaelder, Xavier; Flaschenriem, Christine; Holland, Patrick L.

    2010-01-01

    Reaction of 1-adamantyl azide with iron(I) diketiminate precursors gives metastable but isolable imidoiron(III) complexes LFe=NAd (L = bulky β-diketiminate ligand; Ad = 1-adamantyl). This paper addresses: (1) the spectroscopic and structural characterization of the Fe=N multiple bond in these interesting three-coordinate iron imido complexes, and (2) the mechanism through which the imido complexes form. The iron(III) imido complexes have been examined by 1H NMR and EPR spectroscopies and temperature-dependent magnetic susceptibility (SQUID), and structurally characterized by crystallography and/or X-ray absorption (EXAFS) measurements. These data show that the imido complexes have quartet ground states and short (1.68 ± 0.01 Å) iron-nitrogen bonds. The formation of the imido complexes proceeds through unobserved iron–RN3 intermediates, which are indicated by QM/MM computations to be best described as iron(II) with an RN3 radical anion. The radical character on the organoazide bends its NNN linkage to enable easy N2 loss and imido complex formation. The product distribution between imidoiron(III) products and hexazene-bridged diiron(II) products is solvent-dependent, and the solvent dependence can be explained by coordination of certain solvents to the iron(I) precursor prior to interaction with the organoazide. PMID:20524625

  10. [Synthesis, characterization and luminescence properties of novel beta-diketone and Eu(III) ternary complex].

    PubMed

    Cheng, Guo; Wei, Chang-Ping; Ren, Xiao-Ming; Wang, He; Wei, Wen-Tao

    2011-09-01

    The novel beta-diketone 1-(4-bromophenyl)-3-phenylpropane-1, 3-dione (L) was synthesized at room temperature by classical Claisen condensation reaction. With the beta-diketone L as the first ligand and phen as the secondary ligand, and a new rare-earth Eu (III) ternary complex was prepared. The ligand L and ternary complex were characterized by elemental analysis, IR spectra, UV spectra and fluorescence spectra. IR spectra indicated that: the novel ligand L contained the structure of beta-diketone, where the content of enol was high; the Eu3+ ion in the ternary complex was coordinated with six oxygen atoms of three L ligands and two nitrogen atoms of the second ligand phen. UV spectra showed that the main absorption was from the first ligand L in the Eu (III) ternary complex. The excitation and emission spectra of the ternary complex were measured and investigated. Fluorescence spectra demonstrated that the ternary complex could emit characteristic fluorescence of rare earth Eu3+ ion and the strongest emission band was narrow which was attributed to the 5 D0 --> 7 F2 transitions of the 4f electrons of the central Eu3+ ions. So, the new Eu(III) ternary complex is an excellent red-emitter which would be regarded as a valuable material with bright red fluorescence because it presents good monochromaticity.

  11. Spontaneous Tl(I)-to-Tl(III) oxidation in dynamic heterobimetallic Hg(II)/Tl(I) porphyrin complexes.

    PubMed

    Ndoyom, Victoria; Fusaro, Luca; Roisnel, Thierry; Le Gac, Stéphane; Boitrel, Bernard

    2016-01-11

    Strapped heterobimetallic Hg(II)/Tl(I) porphyrin complexes, with both metal ions bridged by the N-core in a dynamic way, undergo spontaneous Tl(I)-to-Tl(III) oxidation leading to a mono-Tl(III) complex and a mixed valence Tl(I)/Tl(III) bimetallic complex. It provides a new opportunity to tune metal ion translocations in bimetallic porphyrin systems.

  12. The role of geochemistry and energetics in the evolution of modern respiratory complexes from a proton-reducing ancestor.

    PubMed

    Schut, Gerrit J; Zadvornyy, Oleg; Wu, Chang-Hao; Peters, John W; Boyd, Eric S; Adams, Michael W W

    2016-07-01

    Complex I or NADH quinone oxidoreductase (NUO) is an integral component of modern day respiratory chains and has a close evolutionary relationship with energy-conserving [NiFe]-hydrogenases of anaerobic microorganisms. Specifically, in all of biology, the quinone-binding subunit of Complex I, NuoD, is most closely related to the proton-reducing, H2-evolving [NiFe]-containing catalytic subunit, MbhL, of membrane-bound hydrogenase (MBH), to the methanophenzine-reducing subunit of a methanogenic respiratory complex (FPO) and to the catalytic subunit of an archaeal respiratory complex (MBX) involved in reducing elemental sulfur (S°). These complexes also pump ions and have at least 10 homologous subunits in common. As electron donors, MBH and MBX use ferredoxin (Fd), FPO uses either Fd or cofactor F420, and NUO uses either Fd or NADH. In this review, we examine the evolutionary trajectory of these oxidoreductases from a proton-reducing ancestral respiratory complex (ARC). We hypothesize that the diversification of ARC to MBH, MBX, FPO and eventually NUO was driven by the larger energy yields associated with coupling Fd oxidation to the reduction of oxidants with increasing electrochemical potential, including protons, S° and membrane soluble organic compounds such as phenazines and quinone derivatives. Importantly, throughout Earth's history, the availability of these oxidants increased as the redox state of the atmosphere and oceans became progressively more oxidized as a result of the origin and ecological expansion of oxygenic photosynthesis. ARC-derived complexes are therefore remarkably stable respiratory systems with little diversity in core structure but whose general function appears to have co-evolved with the redox state of the biosphere. This article is part of a Special Issue entitled Respiratory Complex I, edited by Volker Zickermann and Ulrich Brandt. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Cytotoxic activity of new neodymium (III) complexes of bis-coumarins.

    PubMed

    Kostova, Irena; Manolov, Ilia; Momekov, Georgi

    2004-09-01

    Complexes of neodymium (III) with bis-coumarins: 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one); bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-2-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-4-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane were synthesized by reaction of neodymium (III) salt and the ligands, in amounts equal to metal:ligand molar ratio of 1:2. The complexes were prepared by adding an aqueous solution of neodymium (III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to ca. 5.0 by adding dilute solution of sodium hydroxide. The neodymium (III) complexes with bis-coumarins were characterized by different physicochemical methods-elemental analysis, IR-, (1)H- and (13)C-NMR-spectroscopies and mass-spectral data. The spectral data of neodymium (III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the Nd (III) complexes the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the nu(C=O) red shift observed, participation of the carbonyl groups in the coordination to the metal ion was also suggested. Cytotoxic screening by MTT assay was carried out. The complexes were tested on HL-60, HL-60/Dox and SKW-3 cell lines. The overall results from the preliminary screening program revealed that all of the new Nd (III) complexes reach 50% inhibition of the malignant cells proliferation and thus could be considered as biologically active. On the basis of the IC(50) values obtained compounds Nd(L(1))(OH).H(2)O and Nd(L(3))(OH).2H(2)O were found to exert superior activity in comparison to the remaining complexes.

  14. Synthesis and characterization of dopamine substitue tripodal trinuclear [(salen/salophen/salpropen)M] (Mdbnd Cr(III), Mn(III), Fe(III) ions) capped s-triazine complexes: Investigation of their thermal and magnetic properties

    NASA Astrophysics Data System (ADS)

    Uysal, Şaban; Koç, Ziya Erdem

    2016-04-01

    In this work, we aimed to synthesize and characterize a novel tridirectional ligand including three catechol groups and its novel tridirectional-trinuclear triazine core complexes. For this purpose, we used melamine (2,4,6-triamino-1,3,5-triazine) (MA) as starting material. 2,4,6-tris(4-carboxybenzimino)-1,3,5-triazine (II) was synthesized by the reaction of an equivalent melamine (I) and three equivalent 4-carboxybenzaldehyde. 4,4‧,4″-((1E,1‧E,1″E)-((1,3,5-triazine-2,4,6-triyl)tris(azanylylidene))tris(methanylylidene))tris(N-(3,4-dihydroxyphenethyl)benzamide) L (IV) was synthesized by the reaction of one equivalent (II) and three equivalent dopamine (3,4-dihydroxyphenethylamine) (DA) by using two different methods. (II, III, IV) and nine novel trinuclear Cr(III), Mn(III) and Fe(III) complexes of (IV) were characterized by means of elemental analyses, 1H NMR, FT-IR spectrometry, LC-MS (ESI+) and thermal analyses. The metal ratios of the prepared complexes were performed using Atomic Absorption Spectrophotometry (AAS). We also synthesized novel tridirectional-trinuclear systems and investigated their effects on magnetic behaviors of [salen, salophen, salpropen Cr(III)/Mn(III)/Fe(III)] capped complexes. The complexes were determined to be low-spin distorted octahedral Mn(III) and Fe(III), and distorted octahedral Cr(III) all bridged by catechol group.

  15. Luminescent Alkyne-Bearing Terbium(III) Complexes and Their Application to Bioorthogonal Protein Labeling.

    PubMed

    O'Malley, William I; Abdelkader, Elwy H; Aulsebrook, Margaret L; Rubbiani, Riccardo; Loh, Choy-Theng; Grace, Michael R; Spiccia, Leone; Gasser, Gilles; Otting, Gottfried; Tuck, Kellie L; Graham, Bim

    2016-02-15

    Two new bifunctional macrocyclic chelate ligands that form luminescent terbium(III) complexes featuring an alkyne group for conjugation to (bio)molecules via the Cu(I)-catalyzed "click" reaction were synthesized. Upon ligation, the complexes exhibit a significant luminescent enhancement when excited at the λ(max) of the "clicked" products. To demonstrate the utility of the complexes for luminescent labeling, they were conjugated in vitro to E. coli aspartate/glutamate-binding protein incorporating a genetically encoded p-azido-L-phenylalanine or p-(azidomethyl)-L-phenylalanine residue. The complexes may prove useful for time-gated assay applications.

  16. Theoretical studies on the photophysical properties of some Iridium (III) complexes used for OLED

    NASA Astrophysics Data System (ADS)

    Urinda, Sharmistha; Das, Goutam; Pramanik, Anup; Sarkar, Pranab

    2016-09-01

    The structural and photophysical properties of four heteroleptic Iridium (III) complexes, based on 1-phenylpyrazole ligand, have been investigated theoretically. The effect of chemical substitution on the absorption and the emission spectra of the complexes has been studied and compared with the experimental data. We observe a significant structural change in the lowest triplet excited state as compared to the ground singlet state. We compute the emission wavelength of the complexes by considering the spin-orbit coupling. Using these understandings, we predict two new complexes having deeper blue emission which are supposed to be better efficient OLED materials.

  17. DNA interaction of europium(III) complex containing 2,2'-bipyridine and its antimicrobial activity.

    PubMed

    Jahani, Shohreh; Khorasani-Motlagh, Mozhgan; Noroozifar, Meissam

    2016-01-01

    The interaction of native fish salmon DNA (FS-DNA) with [Eu(bpy)3Cl2(H2O)]Cl, where bpy is 2,2'-bipyridine, is studied at physiological pH in Tris-HCl buffer by spectroscopic methods, viscometric techniques as well as circular dichroism (CD). These experiments reveal that Eu(III) complex has interaction with FS-DNA. Moreover, binding constant and binding site size have been determined. The value of Kb has been defined 2.46 ± .02 × 10(5) M(-1). The thermodynamic parameters are calculated by Van't Hoff equation, the results show that the interaction of the complex with FS-DNA is an entropically driven phenomenon. CD spectroscopy followed by viscosity as well as fluorescence and UV--Vis measurements indicate that the complex interacts with FS-DNA via groove binding mode. Also, the synthesized Eu(III) complex has been screened for antimicrobial activities.

  18. Modeling rare earth complexes: Sparkle/PM3 parameters for thulium(III)

    NASA Astrophysics Data System (ADS)

    Freire, Ricardo O.; Rocha, Gerd B.; Simas, Alfredo M.

    2006-07-01

    The Sparkle model, recently defined for Tm(III) within AM1 [R.O. Freire, G.B. Rocha, A.M. Simas, Chem. Phys. Lett. 411 (2005) 61], is now extended to PM3. For the same 15 complexes previously used, the Sparkle/PM3 unsigned mean error, for all interatomic distances between the Tm(III) ion and the directly coordinating oxygen or nitrogen atoms, is 0.08 Å, a level of accuracy equivalent to the Sparkle/AM1 figure of 0.07 Å, as well as to results from present day ab initio effective core potential calculations. The results thus indicate that both Sparkle/AM1 and Sparkle/PM3 models may prove useful for luminescent Tm(III) complex design.

  19. A Neutrally Charged Trimethylmanganese(III) Complex: Synthesis, Characterization, and Disproportionation Chemistry

    SciTech Connect

    Stalzer, Madelyn M.; Telser, Joshua; Krzystek, Jurek; Motta, Alessandro; Delferro, Massimiliano; Marks, Tobin J.

    2016-08-22

    The synthesis and properties of an unusual, neutrally charged and volatile N,N,N',N'-tetramethylethylenediamine trimethyl manganese(III) complex, (TMEDA)MnMe3, are described, along with its facile disproportionation to the corresponding Mn(II) and Mn(IV) complexes. Characterization by single-crystal XRD, UV-vis spectroscopy, high-frequency and -field EPR (HFEPR), magnetic susceptibility, and density functional theory (DFT) computations indicate that the (TMEDA)MnMe3 electronic structure can be described as largely square pyramidal Mn(III) centered. The paucity of manganese(III) polyalkyls and the simplicity and reactivity of this compound implicate it as a potentially useful synthetic building block.

  20. Geometric and Electronic Structure of a Peroxomanganese(III) Complex Supported by a Scorpionate Ligand

    PubMed Central

    Colmer, Hannah E.; Geiger, Robert A.; Leto, Domenick F.; Wijeratne, Gayan B.; Day, Victor W.; Jackson, Timothy A.

    2014-01-01

    A monomeric MnII complex has been prepared with the facially-coordinating TpPh2 ligand, (TpPh2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate). The X-ray crystal structure shows three coordinating solvent molecules resulting in a six-coordinate complex with Mn-ligand bond lengths that are consistent with a high-spin MnII ion. Treatment of this MnII complex with excess KO2 at room temperature resulted in the formation of a MnIII-O2 complex that is stable for several days at ambient conditions, allowing for the determination of the X-ray crystal structure of this intermediate. The electronic structure of this peroxomanganese(III) adduct was examined by using electronic absorption, electron paramagnetic resonance (EPR), low-temperature magnetic circular dichroism (MCD), and variable-temperature variable-field (VTVH) MCD spectroscopies. Density functional theory (DFT), time-dependent (TD)-DFT, and multireference ab initio CASSCF/NEVPT2 calculations were used to assign the electronic transitions and further investigate the electronic structure of the peroxomanganese(III) species. The lowest ligand-field transition in the electronic absorption spectrum of the MnIII-O2 complex exhibits a blue shift in energy compared to other previously characterized peroxomanganese(III) complexes that results from a large axial bond elongation, reducing the metal-ligand covalency and stabilizing the σ-antibonding Mn dz2 MO that is the donor MO for this transition. PMID:25312785

  1. Investigation of the extraction complexes of light lanthanides(III) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid by EXAFS, IR, and MS in comparison with the americium(III) complex.

    PubMed

    Guoxin, Tian; Yongjun, Zhu; Jingming, Xu; Ping, Zhang; Tiandou, Hu; Yaning, Xie; Jing, Zhang

    2003-02-10

    The structure of the extraction complexes of light lanthanides (La(III), Nd(III), Eu(III)) with bis(2,4,4-trimethylpentyl)dithiophosphinic acid (HBTMPDTP) have been characterized with extended X-ray absorption fine structure spectroscopy (EXAFS), IR, and MS; the IR spectrum of the extraction complex of (241)Am with HBTMPDTP has been studied too. The molecular formula of the extraction complexes of lanthanides is deduced to be HML(4).H(2)O (M = La, Nd, Eu; L = anion of HBTMPDTP). The coordination number of Ln(III) in the complexes is 8; the coordinated donor atoms are 7 sulfur atoms from 4 HBTMDTP molecules and 1 O atom from a hydrated water molecule. With the increase of the atomic number of Ln, the coordination bond lengths of Ln-O and Ln-S decrease in the complexes. For La(III), Nd(III), and Eu(III), the coordination bond lengths of Ln-O are 2.70, 2.56, and 2.50, respectively, the coordination bond lengths of Ln-S are 3.01, 2.91, and 2.84, respectively, and the average distances between Ln and P atoms are 3.60, 3.53, and 3.46, respectively. The structure of the extraction complexes of Ln(III) with HBTMDTP is different from that of the Am(III) extraction complex. The results of IR show that there is no water coordinated with Am in the extraction complex. The molecular formula of the complex of Am(III) is deduced as being HAmL(4), and there are 8 S atoms from 4 HBTMPDTP molecules coordinated with Am. Composition and structure differences of the extraction complexes may be one of the most most important factors affecting the excellent selectivity of HBTMPDTP for Am(III) over Ln(III).

  2. Iridium(III) soft salts from dinuclear cationic and mononuclear anionic complexes for OLED devices.

    PubMed

    Nasr, Gihane; Guerlin, Audrey; Dumur, Frédéric; Beouch, Layla; Dumas, Eddy; Clavier, Gilles; Miomandre, Fabien; Goubard, Fabrice; Gigmes, Didier; Bertin, Denis; Wantz, Guillaume; Mayer, Cédric R

    2011-10-14

    Two iridium(III) soft salts based on ion-paired dinuclear cationic and mononuclear anionic complexes were designed and investigated as phosphorescent emitters for solution processed OLEDs. New dinuclear cationic complexes were prepared with two different bridging ligands, a carbazole and a phenylene spacer. Best devices were designed with the soft salt bearing a carbazole moiety. This journal is © The Royal Society of Chemistry 2011

  3. Structural studies of lanthanide(III) 1,2-ethylene-diphosphonic acid complexes

    SciTech Connect

    McIlwraith, H.; Zhang, J.; Rogers, R.D.

    1995-12-31

    1,2-Ethylenediphosphonic acid can be classified in a class of extractants known as thermally unstable complexants (TUCS). Extraction accomplished using TUCS ligands can be followed by thermal degradation of the extractant. Despite their proposed utility in separation, few structures of lanthanide(III)/TUCS complexes are known. Structural studies can help us to understand the extraction mechanism and the interaction between metal ions and the ligand.

  4. Synthesis and spectroscopic studies of iron (III) complex with a quinolone family member (pipemidic acid)

    NASA Astrophysics Data System (ADS)

    Skrzypek, D.; Szymanska, B.; Kovala-Demertzi, Dimitra; Wiecek, Joanna; Talik, E.; Demertzis, Mavroudis A.

    2006-12-01

    The interaction of iron (III) with pipemidic acid, Hpipem, afforded the complex [Fe (pipem) (HO)2 (H2O)]2. The new complex has been characterised by elemental analyses, infra-red, EPR and XPS spectroscopies. The monoanion, pipem, exhibits O, O ligation through the carbonyl and carboxylato oxygen atoms. Six coordinate dimer distorted octahedral configuration has been proposed for [Fe (pipem) (HO)2 (H2O)]2.

  5. Spectroscopic characterization of genotoxic chromium(V) peptide complexes: Oxidation of Chromium(III) triglycine, tetraglycine and pentaglycine complexes.

    PubMed

    Headlam, Henrietta A; Lay, Peter A

    2016-09-01

    Evidence is growing that metabolites of Cr(III) dietary supplements are partially oxidized to carcinogenic Cr(VI) and Cr(V) in vivo. Hence, we examined oxidations of Cr(III) peptide (triglycine, tetraglycine and pentaglycine) complexes to Cr(VI) and Cr(V) by PbO2 at 37°C and physiological pH values between 3.85 and 7.4. The products were characterized by EPR and UV/Vis spectroscopies and electrospray mass spectrometry. At pH3.85, the monomeric Cr(V) complexes produced were relatively unstable and degraded over min to hr under the acidic conditions. The triglycine and tetraglycine Cr(V) complexes had five-line (14)N-superhyperfine-coupled EPR signals; giso, (AN) values 1.9824 (2.44×10(-4)cm(-1)) and 1.9825 (2.43×10(-4)cm(-1)), respectively. The pentaglycine Cr(V) complex had a seven-line (14)N-superhyperfine-coupled EPR signal: giso=1.9844; AN=2.27×10(-4)cm(-1). In phosphate buffer (pH7.4 and 5.85), several Cr(V) intermediates were produced, but Cr(VI) was the end product. For the triglycine, tetraglycine and pentaglycine Cr(V) complexes, the giso (AN, 10(-4)cm(-1)) values were 1.9831 (2.17), 1.9843 (2.27) and 1.9844 (2.30), respectively. A second EPR signal with unresolved superhyperfine structure was observed at giso~1.966. At 1min, the tetraglycine and pentaglycine Cr(V) complexes, had another signal at giso~1.978, which decayed relative to the other signals with time. This chemistry has relevance to: (i) certain types of DNA damage produced by Cr carcinogens; (ii) the intracellular oxidation of Cr(III) to Cr(VI); and (iii) redox recycling of Cr(III) metabolites formed from both the intracellular reduction of carcinogenic Cr(VI) and from Cr(III) supplements.

  6. Synthesis and luminescence modulation of pyrazine-based gold(III) pincer complexes.

    PubMed

    Fernandez-Cestau, Julio; Bertrand, Benoît; Blaya, Maria; Jones, Garth A; Penfold, Thomas J; Bochmann, Manfred

    2015-12-04

    The first examples of pyrazine-based gold(III) pincer complexes are reported; their intense photoemissions can be modified by protonation, N-alkylation or metal ions, without the need for altering the ligand framework. Emissions shift from red (77 K) to blue (298 K) due to thermally activated delayed fluorescence (TADF).

  7. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance[].

    PubMed

    Moore, Evan G; D'Aléo, Anthony; Xu, Jide; Raymond, Kenneth N

    2009-10-13

    The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV/visible and then efficiently transfer the energy to the lanthanoid center. The synthesis and the complexation of Ln(III) cations (Ln=Eu; Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu(III) complex ([Eu(3LI-bis-LYS-1,2-HOPO)](-)) has been evaluated in terms of its thermodynamic stability, UV/visible absorption and luminescence properties. For this complex the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid (DTPA) at pH= 7.4. This Eu(III) complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH= 7.4) when compared to other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)](-). This overall improvement was achieved by saturating the coordination sphere of the Eu(III) cation, yielding an increased metal centered efficiency by excluding solvent water molecules from the metal's inner sphere.

  8. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance[1

    PubMed Central

    Moore, Evan G.; D’Aléo, Anthony; Xu, Jide; Raymond, Kenneth N.

    2010-01-01

    The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV/visible and then efficiently transfer the energy to the lanthanoid center. The synthesis and the complexation of Ln(III) cations (Ln=Eu; Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu(III) complex ([Eu(3LI-bis-LYS-1,2-HOPO)]−) has been evaluated in terms of its thermodynamic stability, UV/visible absorption and luminescence properties. For this complex the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid (DTPA) at pH= 7.4. This Eu(III) complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH= 7.4) when compared to other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)]−. This overall improvement was achieved by saturating the coordination sphere of the Eu(III) cation, yielding an increased metal centered efficiency by excluding solvent water molecules from the metal’s inner sphere. PMID:20543961

  9. A neutral dinuclear Ir(iii) complex for anti-counterfeiting and data encryption.

    PubMed

    Jiang, Yang; Li, Guangfu; Che, Weilong; Liu, Yingjie; Xu, Bin; Shan, Guogang; Zhu, Dongxia; Su, Zhongmin; Bryce, Martin R

    2017-03-09

    A neutral dinuclear Ir(iii) Schiff base complex PIBIP has been synthesized and shown to exhibit both piezochromic luminescence (PCL) and aggregation induced emission (AIE) behaviour. An efficient second-level anti-counterfeit trademark and a data encryption device were fabricated using PIBIP as the active material.

  10. Synthesis and Base Hydrolysis of a Cobalt(III) Complex Coordinated by a Thioether Ligand

    ERIC Educational Resources Information Center

    Roecker, Lee

    2008-01-01

    A two-week laboratory experiment for students in advanced inorganic chemistry is described. Students prepare and characterize a cobalt(III) complex coordinated by a thioether ligand during the first week of the experiment and then study the kinetics of Co-S bond cleavage in basic solution during the second week. The synthetic portion of the…

  11. Synthesis and Base Hydrolysis of a Cobalt(III) Complex Coordinated by a Thioether Ligand

    ERIC Educational Resources Information Center

    Roecker, Lee

    2008-01-01

    A two-week laboratory experiment for students in advanced inorganic chemistry is described. Students prepare and characterize a cobalt(III) complex coordinated by a thioether ligand during the first week of the experiment and then study the kinetics of Co-S bond cleavage in basic solution during the second week. The synthetic portion of the…

  12. Eu(III) Complexes of Octadentate 1-Hydroxy-2-pyridinones: Stability and Improved Photophysical Performance

    SciTech Connect

    Moore, Evan G.; D'Aleo, Anthony; Xu, Jide; Raymond, Kenneth N.

    2009-05-29

    The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV-visible and then efficiently transfer the energy to the lanthanoid centre. The synthesis and the complexation of Ln{sup III} cations (Ln = Eu, Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two L-lysine units (3LI-bis-LYS) is described. This octadentate Eu{sup III} complex ([Eu(3LI-bis-LYS-1,2-HOPO)]{sup -}) has been evaluated in terms of its thermodynamic stability, UV-visible absorption and luminescence properties. For this complex, the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid at pH = 7.4. This Eu{sup III} complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH = 7.4) when compared with other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)]{sup -}. This overall improvement was achieved by saturating the coordination sphere of the Eu{sup III} cation, yielding an increased metal-centred efficiency by excluding solvent water molecules from the metal's inner sphere.

  13. Exploring the Influence of Diamagnetic Ions on the Mechanism of Magnetization Relaxation in {Co(III)2Ln(III)2} (Ln = Dy, Tb, Ho) "Butterfly" Complexes.

    PubMed

    Vignesh, Kuduva R; Langley, Stuart K; Murray, Keith S; Rajaraman, Gopalan

    2017-03-06

    The synthesis and magnetic and theoretical studies of three isostructural heterometallic [Co(III)2Ln(III)2(μ3-OH)2(o-tol)4(mdea)2(NO3)2] (Ln = Dy (1), Tb (2), Ho (3)) "butterfly" complexes are reported (o-tol = o-toluate, (mdea)(2-) = doubly deprotonated N-methyldiethanolamine). The Co(III) ions are diamagnetic in these complexes. Analysis of the dc magnetic susceptibility measurements reveal antiferromagnetic exchange coupling between the two Ln(III) ions for all three complexes. ac magnetic susceptibility measurements reveal single-molecule magnet (SMM) behavior for complex 1, in the absence of an external magnetic field, with an anisotropy barrier Ueff of 81.2 cm(-1), while complexes 2 and 3 exhibit field induced SMM behavior, with a Ueff value of 34.2 cm(-1) for 2. The barrier height for 3 could not be quantified. To understand the experimental observations, we performed DFT and ab initio CASSCF+RASSI-SO calculations to probe the single-ion properties and the nature and magnitude of the Ln(III)-Ln(III) magnetic coupling and to develop an understanding of the role the diamagnetic Co(III) ion plays in the magnetization relaxation. The calculations were able to rationalize the experimental relaxation data for all complexes and strongly suggest that the Co(III) ion is integral to the observation of SMM behavior in these systems. Thus, we explored further the effect that the diamagnetic Co(III) ions have on the magnetization blocking of 1. We did this by modeling a dinuclear {Dy(III)2} complex (1a), with the removal of the diamagnetic ions, and three complexes of the types {K(I)2Dy(III)2} (1b), {Zn(II)2Dy(III)2} (1c), and {Ti(IV)2Dy(III)2} (1d), each containing a different diamagnetic ion. We found that the presence of the diamagnetic ions results in larger negative charges on the bridging hydroxides (1b > 1c > 1 > 1d), in comparison to 1a (no diamagnetic ion), which reduces quantum tunneling of magnetization effects, allowing for more desirable SMM characteristics

  14. Dissolution of Fe(III)(hydr) oxides by metal-EDTA complexes

    SciTech Connect

    Nowack, B.; Sigg, L. |

    1997-03-01

    The dissolution of Fe(III)(hydr)oxides (goethite and hydrous ferric oxide) by metal-EDTA complexes occurs by ligand-promoted dissolution. The process is initiated by the adsorption of metal-EDTA complexes to the surface and is followed by the dissociation of the complex at the surface and the release of Fe(III)EDTA into solution. The dissolution rate is decreased to a great extent if EDTA is complexed by metals in comparison to the uncomplexed EDTA. The rate decreases in the order EDTA > CaEDTA > PbEDTA > ZnEDTA > CuEDTA > Co(II)EDTA > NiEDTA. Two different rate-limiting steps determine the dissolution process: (1) detachment of Fe(III) from the oxide-structure and (2) dissociation of the metal-EDTA complexes. In the case of goethite, step 1 is slower than step 2 and the dissolution rates by various metals are similar. In the case of hydrous ferric oxide, step 2 is rate-limiting and the effect of the complexed metal is very pronounced. 35 refs., 11 figs., 4 tabs.

  15. Mononuclear ruthenium(III) complexes containing chelating thiosemicarbazones: Synthesis, characterization and catalytic property

    NASA Astrophysics Data System (ADS)

    Raja, N.; Ramesh, R.

    2010-02-01

    Mononuclear ruthenium(III) complexes of the type [RuX(EPh 3) 2(L)] (E = P or As; X = Cl or Br; L = dibasic terdentate dehydroacetic acid thiosemicarbazones) have been synthesized from the reaction of thiosemicarbazone ligands with ruthenium(III) precursors, [RuX 3(EPh 3) 3] (where E = P, X = Cl; E = As, X = Cl or Br) and [RuBr 3(PPh 3) 2(CH 3OH)] in benzene. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-vis and EPR spectral data. These complexes are paramagnetic and show intense d-d and charge transfer transitions in dichloromethane. The complexes show rhombic EPR spectra at LNT which are typical of low-spin distorted octahedral ruthenium(III) species. All the complexes are redox active and display an irreversible metal centered redox processes. Complex [RuCl(PPh 3) 2(DHA-PTSC)] ( 5) was used as catalyst for transfer hydrogenation of ketones in the presence of isopropanol/KOH and was found to be the active species.

  16. The mechanism of coupling between electron transfer and proton translocation in respiratory complex I.

    PubMed

    Sazanov, Leonid A

    2014-08-01

    NADH-ubiquinone oxidoreductase (complex I) is the first and largest enzyme in the respiratory chain of mitochondria and many bacteria. It couples the transfer of two electrons between NADH and ubiquinone to the translocation of four protons across the membrane. Complex I is an L-shaped assembly formed by the hydrophilic (peripheral) arm, containing all the redox centres performing electron transfer and the membrane arm, containing proton-translocating machinery. Mitochondrial complex I consists of 44 subunits of about 1 MDa in total, whilst the prokaryotic enzyme is simpler and generally consists of 14 conserved "core" subunits. Recently we have determined the first atomic structure of the entire complex I, using the enzyme from Thermus thermophilus (536 kDa, 16 subunits, 9 Fe-S clusters, 64 TM helices). Structure suggests a unique coupling mechanism, with redox energy of electron transfer driving proton translocation via long-range (up to ~200 Å) conformational changes. It resembles a steam engine, with coupling elements (akin to coupling rods) linking parts of this molecular machine.

  17. Targeting metabolic flexibility by simultaneously inhibiting respiratory complex I and lactate generation retards melanoma progression

    PubMed Central

    Chaube, Balkrishna; Malvi, Parmanand; Singh, Shivendra Vikram; Mohammad, Naoshad; Meena, Avtar Singh; Bhat, Manoj Kumar

    2015-01-01

    Melanoma is a largely incurable skin malignancy owing to the underlying molecular and metabolic heterogeneity confounded by the development of resistance. Cancer cells have metabolic flexibility in choosing either oxidative phosphorylation (OXPHOS) or glycolysis for ATP generation depending upon the nutrient availability in tumor microenvironment. In this study, we investigated the involvement of respiratory complex I and lactate dehydrogenase (LDH) in melanoma progression. We show that inhibition of complex I by metformin promotes melanoma growth in mice via elevating lactate and VEGF levels. In contrast, it leads to the growth arrest in vitro because of enhanced extracellular acidification as a result of increased glycolysis. Inhibition of LDH or lactate generation causes decrease in glycolysis with concomitant growth arrest both in vitro and in vivo. Blocking lactate generation in metformin-treated melanoma cells results in diminished cell proliferation and tumor progression in mice. Interestingly, inhibition of either LDH or complex I alone does not induce apoptosis, whereas inhibiting both together causes depletion in cellular ATP pool resulting in metabolic catastrophe induced apoptosis. Overall, our study suggests that LDH and complex I play distinct roles in regulating glycolysis and cell proliferation. Inhibition of these two augments synthetic lethality in melanoma. PMID:26484566

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

    PubMed Central

    Ajali, Uzoechi; Ukoha, Pius O.

    2014-01-01

    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. PMID:25505991

  19. Thermodynamic Features of the Complexation of Neodymium(III) and Americium(III) by Lactate in Trifluoromethanesulfonate Media.

    SciTech Connect

    Peter R. Zalupski; Leigh R. Martin; Kenneth L. Nash

    2010-10-01

    The protonation of lactate has been studied in a variety of electrolyte solutions using microcalorimetry to reveal a distinct medium influence imposed on the thermochemistry of the investigated equilibrium. The thermochemistry of lactate protonation, when studied directly in 1.0 M sodium lactate, agreed well with the studies performed in trifluoromethanesulfonate (triflate). This thermodynamic agreement suggests that the physical chemistry of lactate in the solutions applicable to the TALSPEAK process – a solvent extraction method for separating trivalent actinides from trivalent lanthanides within the scope of used nuclear fuel processing efforts – may be simulated in triflate solutions. Potentiometry, spectrophotometry and microcalorimetry have been subsequently used to study the thermodynamic features of neodymium and americium complexation by lactate using triflate as a strong background electrolyte. Three successive mononuclear lactate complexes were identified for Nd(III) and Am(III). The stability constants for neodymium, log ß1 = 2.60 ± 0.01, log ß2 = 4.66 ± 0.02 and log ß3 = 5.6 ± 0.1, and for americium, log ß1 = 2.60 ± 0.06, log ß2 = 4.7 ± 0.1 and log ß3 = 6.2 ± 0.2, were found to closely agree with the thermodynamic studies reported in sodium perchlorate solutions. Consequently, the thermodynamic medium effect, imposed on the TALSPEAK-related solution equilibria by the presence of strong background electrolytes such as NaClO4 and NaNO3, do not significantly impact the speciation in solution.

  20. Photolysis of Iron (III) carboxylate complexes relevant for tropospheric aqueous particles and cloud droplets

    NASA Astrophysics Data System (ADS)

    Herrmann, H.; Weller, C.; Bräuer, P.; Tilgner, A.

    2012-12-01

    Absorption spectra and Fe(II) quantum yields of iron(III) coordination complexes with oxalate, malonate, succinate, glutarate, tartronate, tartrate, gluconate, glyoxalate and pyruvate were experimentally determined. Measured quantum yields of malonate, glutarate and gluconate complexes are in the range of 0.02 < Φ < 0.05, while succinate, tartrate, pyruvate, glyoxylate and tartronate complexes show values between 0.12 < Φ < 1.21. For some systems, the effect of dissolved oxygen on the quantum yields was considered. Oxygen generally lowers the Fe(II) quantum yield for the complexes with tartronate, pyruvate, glyoxalate and gluconate. No oxygen effect was observed with tartrate and, surprisingly, in the case of succinate complexes a higher quantum yield was observed at 351 nm under increased oxygen concentrations in solution. In the case of oxalate, a dependence of the quantum yield on the initial concentration of iron(III) oxalato complexes was observed. A kinetic simulation of the reaction system after the photolysis was performed for oxalate, succinate, glyoxalate and tartrate complexes to characterize the influence of secondary thermal reactions on the quantum yield. A tropospheric chemistry simulation with the multiphase chemistry mechanism CAPRAM involving the photolysis of the studied complexes and subsequent reactions of the resulting species shows that the contribution of the iron complex photochemistry to the formation of oxidants such as the hydroperoxyl radical and its anion, the hydroxyl radical and H2O2 is low in comparison to other sources. However, it is shown that Fe(III) complex photolysis represents a major sink for some ligands in addition to the oxidation via free radicals.

  1. Chlorido-containing ruthenium(II) and iridium(III) complexes as antimicrobial agents.

    PubMed

    Pandrala, Mallesh; Li, Fangfei; Feterl, Marshall; Mulyana, Yanyan; Warner, Jeffrey M; Wallace, Lynne; Keene, F Richard; Collins, J Grant

    2013-04-07

    A series of polypyridyl-ruthenium(II) and -iridium(III) complexes that contain labile chlorido ligands, [{M(tpy)Cl}(2){μ-bb(n)}](2/4+) {Cl-Mbb(n); where M = Ru or Ir; tpy = 2,2':6',2''-terpyridine; and bb(n) = bis[4(4'-methyl-2,2'-bipyridyl)]-1,n-alkane (n = 7, 12 or 16)} have been synthesised and their potential as antimicrobial agents examined. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the series of metal complexes against four strains of bacteria - Gram positive Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA), and Gram negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) - have been determined. All the ruthenium complexes were highly active and bactericidal. In particular, the Cl-Rubb(12) complex showed excellent activity against all bacterial cell lines with MIC values of 1 μg mL(-1) against the Gram positive bacteria and 2 and 8 μg mL(-1) against E. coli and P. aeruginosa, respectively. The corresponding iridium(III) complexes also showed significant antimicrobial activity in terms of MIC values; however and surprisingly, the iridium complexes were bacteriostatic rather than bactericidal. The inert iridium(III) complex, [{Ir(phen)(2)}(2){μ-bb(12)}](6+) {where phen = 1,10-phenanthroline) exhibited no antimicrobial activity, suggesting that it could not cross the bacterial membrane. The mononuclear model complex, [Ir(tpy)(Me(2)bpy)Cl]Cl(2) (where Me(2)bpy = 4,4'-dimethyl-2,2'-bipyridine), was found to aquate very rapidly, with the pK(a) of the iridium-bound water in the corresponding aqua complex determined to be 6.0. This suggests the dinuclear complexes [Ir(tpy)Cl}(2){μ-bb(n)}](4+) aquate and deprotonate rapidly and enter the bacterial cells as 4+ charged hydroxo species.

  2. Phosphorescent iridium(III) complexes: toward high phosphorescence quantum efficiency through ligand control.

    PubMed

    You, Youngmin; Park, Soo Young

    2009-02-28

    Phosphorescent Ir(III) complexes attract enormous attention because they allow highly efficient electrophosphorescence. In pursuing the development of Ir(III) complexes during the last decade, significant progress has been made in terms of the colour-tunability, thermal- and photo-stability, phase homogeneity, and phosphorescence efficiency. By far, extensive synthetic efforts have been focused on the molecular design of ligands to achieve a wide range of phosphorescence colour that is compatible with organic light-emitting device (OLED) applications. In contrast, less has been known about a collective structure-property relationship for phosphorescence quantum efficiency. In fact, a few rule-of-thumbs for high phosphorescence quantum efficiency have been occasionally reported, but a collective rationale is yet to be investigated. In this article, we provide a comprehensive review of 8 different methods reported so far to achieve high phosphorescence quantum efficiency from Ir(III) complexes. The methods included herein are limited to the cases of intramolecular controls, and thus are discussed in terms of variations in ligand structures: (1) geometric isomer control, (2) rigid structure and restricted intramolecular motion, (3) larger mixing of 1MLCT and 3LC states, (4) de-stabilizing a thermally accessible non-emissive state, (5) introducing dendrimer structures, (6) control in substituents of ligands, (7) confining the phosphorescent region of a mixed ligand Ir(III) complex and (8) sensitized phosphorescence by using attached energy donors. Each method is closely related to intramolecular excited state interactions, which strongly affect radiative or non-radiative transitions. A comprehensive understanding of these methods leads us to conclude that the modulation in ligand structures has a profound effect on both the phosphorescence colour and phosphorescence quantum efficiency. Thus, the judicious selection of ligand structures and their chelate disposition

  3. Enhancing the photocytotoxic potential of curcumin on terpyridyl lanthanide(III) complex formation.

    PubMed

    Hussain, Akhtar; Somyajit, Kumar; Banik, Bhabatosh; Banerjee, Samya; Nagaraju, Ganesh; Chakravarty, Akhil R

    2013-01-07

    Lanthanide(III) complexes [Ln(R-tpy)(cur)(NO3)2] (Ln = La(III) in 1, 2; Gd(III) in 5, 6) and [Ln(R-tpy)(scur)(NO3)2] (Ln = La(III) in 3, 4; Gd(III) in 7, 8), where R-tpy is 4′-phenyl-2,2′:6′,2′′-terpyridine (ph-tpy in 1, 3, 5, 7), 4′-(1-pyrenyl)-2,2′:6′,2′′-terpyridine (py-tpy in 2, 4, 6, 8), Hcur is curcumin (in 1, 2, 5, 6) and Hscur is diglucosylcurcumin (in 3, 4, 7, 8), were prepared and their DNA photocleavage activity and photocytotoxicity studied. Complexes [La(ph-tpy)(cur)(NO3)2] (1) and [Gd(ph-tpy)(cur)(NO3)2] (5) were structurally characterized. The complexes in aqueous-DMF showed an absorption band near 430 nm and an emission band near 515 nm when excited at 420 nm. The complexes are moderate binders to calf-thymus DNA. They cleave plasmid supercoiled DNA to its nicked circular form in UV-A (365 nm) and visible light (454 nm) via (1)O2 and ˙OH pathways. The complexes are remarkably photocytotoxic in HeLa cells in visible light (λ = 400–700 nm) and are non-toxic in the dark. FACScan analysis of the HeLa cells treated with 2 and 4 showed cell death via an apoptotic pathway. Nuclear localization of 1–4 is evidenced from confocal imaging on HeLa cells. The hydrolytic instability of curcumin gets significantly reduced upon binding to the lanthanide ions while retaining its photocytotoxic potential.

  4. The origin, composition, and reactivity of dissolved iron(III) complexes in coastal organic- and iron-rich sediments

    NASA Astrophysics Data System (ADS)

    Beckler, Jordon S.; Jones, Morris E.; Taillefert, Martial

    2015-03-01

    The redox chemistry and speciation of Fe in both solid and dissolved phases were characterized in the organic- and Fe-rich sediments of the Satilla River estuary in South-East Georgia (USA) on a series of four cruises between July 2007 and January 2008. Results indicate that dissolved Fe is present in relatively high concentration in the overlying waters at the freshwater end of the estuary and flocculates along the river as the salinity increases downstream. Soluble organic-Fe(III) complexes comprise the majority of dissolved Fe (<0.2 μm) in the suboxic pore waters of the upriver stations that are characterized by high concentrations of poorly crystalline Fe(III) (oxy)hydroxides. In contrast, SO42--reducing conditions downstream prevent the accumulation of organic-Fe(III) in the pore waters by titrating Fe from the sediment. Separation of dissolved Fe by size exclusion chromatography revealed that Fe(II) is complexed by organic ligands in the pore waters while the organic-Fe(III) complexes are either small or highly reactive with the column matrix. Finally, dissimilatory Fe(III) reduction, stimulated by inoculating anaerobic sediments with a Fe(III)-reducing bacterium (FeRB), Shewanella putrefaciens strain 200, increased production of soluble organic-Fe(III) complexes, and addition of reactive Fe(III) hydroxides accelerated the non-reductive dissolution of Fe(III) (oxy)hydroxides irrespective of the presence of exogenous FeRB. These findings suggest soluble organic-Fe(III) complexes in suboxic pore waters may be produced both as intermediates during the dissimilatory reduction of Fe(III) (oxy)hydroxides by Fe(III)-reducing microorganisms and during the oxidation of organic-Fe(II) complexes by Fe(III) (oxy)hydroxides. These soluble organic-Fe(III) complexes are stable in pore waters and may flux from the sediments to the continental shelf.

  5. Iron(III) protoporphyrin IX complexes of the antimalarial Cinchona alkaloids quinine and quinidine.

    PubMed

    de Villiers, Katherine A; Gildenhuys, Johandie; le Roex, Tanya

    2012-04-20

    The antimalarial properties of the Cinchona alkaloids quinine and quinidine have been known for decades. Surprisingly, 9-epiquinine and 9-epiquinidine are almost inactive. A lack of definitive structural information has precluded a clear understanding of the relationship between molecular structure and biological activity. In the current study, we have determined by single crystal X-ray diffraction the structures of the complexes formed between quinine and quinidine and iron(III) protoporphyrin IX (Fe(III)PPIX). Coordination of the alkaloid to the Fe(III) center is a key feature of both complexes, and further stability is provided by an intramolecular hydrogen bond formed between a propionate side chain of Fe(III)PPIX and the protonated quinuclidine nitrogen atom of either alkaloid. These interactions are believed to be responsible for inhibiting the incorporation of Fe(III)PPIX into crystalline hemozoin during its in vivo detoxification. It is also possible to rationalize the greater activity of quinidine compared to that of quinine.

  6. Substrate complexes of human dipeptidyl peptidase III reveal the mechanism of enzyme inhibition

    PubMed Central

    Kumar, Prashant; Reithofer, Viktoria; Reisinger, Manuel; Wallner, Silvia; Pavkov-Keller, Tea; Macheroux, Peter; Gruber, Karl

    2016-01-01

    Human dipeptidyl-peptidase III (hDPP III) is a zinc-dependent hydrolase cleaving dipeptides off the N-termini of various bioactive peptides. Thus, the enzyme is likely involved in a number of physiological processes such as nociception and is also implicated in several forms of cancer. We present high-resolution crystal structures of hDPP III in complex with opioid peptides (Met-and Leu-enkephalin, endomorphin-2) as well as with angiotensin-II and the peptide inhibitor IVYPW. These structures confirm the previously reported large conformational change of the enzyme upon ligand binding and show that the structure of the closed conformation is independent of the nature of the bound peptide. The overall peptide-binding mode is also conserved ensuring the correct positioning of the scissile peptide bond with respect to the catalytic zinc ion. The structure of the angiotensin-II complex shows, how longer peptides are accommodated in the binding cleft of hDPP III. Differences in the binding modes allow a distinction between real substrates and inhibitory peptides or “slow” substrates. The latter displace a zinc bound water molecule necessitating the energetically much less favoured anhydride mechanism as opposed to the favoured promoted-water mechanism. The structural data also form the necessary framework for the design of specific hDPP III inhibitors. PMID:27025154

  7. Spectroscopic and pH-metric studies on the complexation of a novel tripodal amine-phenol ligand towards Al(III), Ga(III) and In(III)

    NASA Astrophysics Data System (ADS)

    Sahoo, Suban K.; Bera, Rati kanta; Kanungo, B. K.; Baral, Minati

    2012-04-01

    The aqueous coordination chemistry of a newly synthesized tripodal amine-phenol ligand, cis,cis-1,3,5-tris{(2-hydroxybenzyl)aminomethyl}cyclohexane (THAC) towards H+, Al3+, Ga3+ and In3+ ions have been investigated in aqueous medium of 0.1 M KCl ionic strength and 25 ± 1 °C by potentiometric and spectrophotometric methods. Three protonation constants assigned to phenolic hydroxyl groups were determined and were used as input data to evaluate the formation constants of the metal complexes. The ligand formed various monomeric metal complex species MLH3, MLH2, MLH, ML and MLH-1 with Ga(III) and In(III); MLH3, ML and MLH-1 with Al(III). The calculated stability constants followed the order Ga(III) > In(III) > Al(III), and their pM values at physiological condition were found to be higher than the corresponding transferrin complexes.

  8. Spectroscopic and pH-metric studies on the complexation of a novel tripodal amine-phenol ligand towards Al(III), Ga(III) and In(III).

    PubMed

    Sahoo, Suban K; Bera, Rati Kanta; Kanungo, B K; Baral, Minati

    2012-04-01

    The aqueous coordination chemistry of a newly synthesized tripodal amine-phenol ligand, cis,cis-1,3,5-tris{(2-hydroxybenzyl)aminomethyl}cyclohexane (THAC) towards H+, Al3+, Ga3+ and In3+ ions have been investigated in aqueous medium of 0.1 M KCl ionic strength and 25±1 °C by potentiometric and spectrophotometric methods. Three protonation constants assigned to phenolic hydroxyl groups were determined and were used as input data to evaluate the formation constants of the metal complexes. The ligand formed various monomeric metal complex species MLH3, MLH2, MLH, ML and MLH(-1) with Ga(III) and In(III); MLH3, ML and MLH(-1) with Al(III). The calculated stability constants followed the order Ga(III)>In(III)>Al(III), and their pM values at physiological condition were found to be higher than the corresponding transferrin complexes.

  9. Homoleptic trimethylsilylacetylide complexes of chromium(III), iron(II), and cobalt(III): syntheses, structures, and ligand field parameters.

    PubMed

    Berben, Louise A; Long, Jeffrey R

    2005-11-14

    A straightforward method for synthesizing soluble homoleptic trimethylsilylacetylide complexes of first-row transition metal ions is presented. Reaction of anhydrous CrCl2 with an excess of LiCCSiMe3 in THF at -25 degrees C affords orange Li3[Cr(CCSiMe3)6].6THF (1), while analogous reactions employing M(CF3SO3)2 (M = Fe or Co) generate pale yellow Li4[Fe(CCSiMe3)6].4LiCCSiMe3.4Et2O (2) and colorless Li3[Co(CCSiMe3)6].6THF (3). Slightly modified reaction conditions lead to Li8[Cr2O4(CCSiMe3)6].6LiCCSiMe3.4glyme (4), featuring a bis-mu-oxo-bridged binuclear complex, and Li3[Co(CCSiMe3)5(CCH)].LiCF3SO3.8THF (5). The crystal structures of 1-3 show the trimethylsilylacetylide complexes to display an octahedral coordination geometry, with M-C distances of 2.077(3), 1.917(7)-1.935(7), and 1.908(3) angstroms for M = Cr(III), Fe(II), and Co(III), respectively, and nearly linear M-C[triple bond]C angles. The UV-visible absorption spectrum of [Cr(CCSiMe3)6]3- in hexanes exhibits one spin-allowed d-d transition (4T2g <-- 4A1g) and three lower-energy spin-forbidden d-d transitions. The spectra of [Fe(CCSiMe3)6]4- and [Co(CCSiMe3)6]3- in acetonitrile display high-intensity charge-transfer bands, which obscure all d-d transitions except for the lowest-energy spin-allowed band (1T1g <-- 1A1g) of the latter complex. Time-dependent density functional theory (TD-DFT) calculations were employed as an aide in assigning the observed transitions. Taken together, the results are most consistent with the ligand field parameters delta(o) = 20,200 cm(-1) and B = 530 cm(-1) for [Cr(CCSiMe3)6]3-, delta(o) = 32 450 cm(-1) and B = 460 cm(-1) for [Fe(CCSiMe3)6]4- and delta(o) = 32 500 cm(-1) and B = 516 cm(-1) for [Co(CCSiMe3)6]3-. Ground-state DFT calculations support the conclusion that trimethylsilylacetylide acts as a pi-donor ligand.

  10. Spectroscopic studies on the interaction between tryptophan-erbium(III) complex and herring sperm DNA.

    PubMed

    Zhao, Na; Wang, Xingming; Pan, Haizhuan; Hu, Yamin; Ding, Lisheng

    2010-05-01

    By means of UV and fluorescence spectra, the binding ratios between Er(III)-Trp and DNA in physiological pH environment (pH 7.40) were determined as n(Trp):n(Er(III))=3:1 and (n)ER(III)(Trp)(3):(n)(DNA) = 2:1, and the apparent molar absorptivity of epsilon(Er(III)-Trp-DNA) is 4.33 x 10(5) L mol(-1)cm(-1) which was confirmed by molar ratio method. The binding constants at different temperatures K(B25 degrees C)(theta)=1.93 x 10(4)L mol(-1) and K(B37 degrees C)(theta)=5.28 x 10(3)L mol(-1) were obtained by double reciprocal method. Thermodynamic function computation demonstrates that Delta(r)H(m)(theta) is the primary driving power of the interaction between Er(III)(Trp)(3) and DNA. By combination analysis of the Scatchard method and CD spectrometry, we suggested that the interaction mode between Er(III)(Trp)(3) complex and herring sperm DNA is groove and intercalation bindings.

  11. Sham feeding disrupts phase III of the duodenal migrating motor complex in humans.

    PubMed

    Pouderoux, P; Veyrac, M; Michel, H

    1995-09-01

    The role of the vagus nerve in the control of the intestinal migrating motor complex (MMC) is unclear. This study aimed to evaluate the effect of physiological vagal stimulation with sham feeding on phase III of the MMC. Antroduodenal motility was recorded in six healthy volunteers. The first phase III was used as a control, and sham feeding was performed during the second phase III. The MMC was disrupted within 1.5 +/- 0.4 min of sham feeding and its duration was shorter than the control phase III. Phase III propagation was inhibited in all subjects, most of them exhibiting no propagation beyond the third duodenal recording site. During sham feeding, the antrum exhibited transient phasic contractions in five out of six subjects. The duodenal motility index recorded for up to 30 min after the onset of the sham feeding was unchanged in five out of six subjects. We conclude that sham feeding consistently interrupted phase III of the duodenal MMC and induced antral contractions, but failed to provoke significant motor events in the duodenum.

  12. Development of a one-run real-time PCR detection system for pathogens associated with bovine respiratory disease complex.

    PubMed

    Kishimoto, Mai; Tsuchiaka, Shinobu; Rahpaya, Sayed Samim; Hasebe, Ayako; Otsu, Keiko; Sugimura, Satoshi; Kobayashi, Suguru; Komatsu, Natsumi; Nagai, Makoto; Omatsu, Tsutomu; Naoi, Yuki; Sano, Kaori; Okazaki-Terashima, Sachiko; Oba, Mami; Katayama, Yukie; Sato, Reiichiro; Asai, Tetsuo; Mizutani, Tetsuya

    2017-03-18

    Bovine respiratory disease complex (BRDC) is frequently found in cattle worldwide. The etiology of BRDC is complicated by infections with multiple pathogens, making identification of the causal pathogen difficult. Here, we developed a detection system by applying TaqMan real-time PCR (Dembo respiratory-PCR) to screen a broad range of microbes associated with BRDC in a single run. We selected 16 bovine respiratory pathogens (bovine viral diarrhea virus, bovine coronavirus, bovine parainfluenza virus 3, bovine respiratory syncytial virus, influenza D virus, bovine rhinitis A virus, bovine rhinitis B virus, bovine herpesvirus 1, bovine adenovirus 3, bovine adenovirus 7, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Trueperella pyogenes, Mycoplasma bovis and Ureaplasma diversum) as detection targets and designed novel specific primer-probe sets for nine of them. The assay performance was assessed using standard curves from synthesized DNA. In addition, the sensitivity of the assay was evaluated by spiking solutions extracted from nasal swabs that were negative by Dembo respiratory-PCR for nucleic acids of pathogens or synthesized DNA. All primer-probe sets showed high sensitivity. In this study, a total of 40 nasal swab samples from cattle on six farms were tested by Dembo respiratory-PCR. Dembo respiratory-PCR can be applied as a screening system with wide detection targets.

  13. Development of a one-run real-time PCR detection system for pathogens associated with bovine respiratory disease complex

    PubMed Central

    KISHIMOTO, Mai; TSUCHIAKA, Shinobu; RAHPAYA, Sayed Samim; HASEBE, Ayako; OTSU, Keiko; SUGIMURA, Satoshi; KOBAYASHI, Suguru; KOMATSU, Natsumi; NAGAI, Makoto; OMATSU, Tsutomu; NAOI, Yuki; SANO, Kaori; OKAZAKI-TERASHIMA, Sachiko; OBA, Mami; KATAYAMA, Yukie; SATO, Reiichiro; ASAI, Tetsuo; MIZUTANI, Tetsuya

    2017-01-01

    Bovine respiratory disease complex (BRDC) is frequently found in cattle worldwide. The etiology of BRDC is complicated by infections with multiple pathogens, making identification of the causal pathogen difficult. Here, we developed a detection system by applying TaqMan real-time PCR (Dembo respiratory-PCR) to screen a broad range of microbes associated with BRDC in a single run. We selected 16 bovine respiratory pathogens (bovine viral diarrhea virus, bovine coronavirus, bovine parainfluenza virus 3, bovine respiratory syncytial virus, influenza D virus, bovine rhinitis A virus, bovine rhinitis B virus, bovine herpesvirus 1, bovine adenovirus 3, bovine adenovirus 7, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Trueperella pyogenes, Mycoplasma bovis and Ureaplasma diversum) as detection targets and designed novel specific primer-probe sets for nine of them. The assay performance was assessed using standard curves from synthesized DNA. In addition, the sensitivity of the assay was evaluated by spiking solutions extracted from nasal swabs that were negative by Dembo respiratory-PCR for nucleic acids of pathogens or synthesized DNA. All primer-probe sets showed high sensitivity. In this study, a total of 40 nasal swab samples from cattle on six farms were tested by Dembo respiratory-PCR. Dembo respiratory-PCR can be applied as a screening system with wide detection targets. PMID:28070089

  14. Intramolecular deactivation processes in complexes of salicylic acid or glycolic acid with Eu(III).

    PubMed

    Kuke, S; Marmodée, B; Eidner, S; Schilde, U; Kumke, M U

    2010-04-01

    The complexation of Eu(III) by 2-hydroxy benzoic acid (2HB) or glycolic acid (GL) was investigated using steady-state and time-resolved laser spectroscopy. Experiments were carried out in H(2)O as well as in D(2)O in the temperature range of 80KIII) luminescence spectra and luminescence decay times were evaluated with respect to the temperature dependence of (i) the luminescence decay time tau, (ii) the energy of the D5(0)-->F7(0) transition, (iii) the width of the D5(0)-->F7(0) transition, and (iv) the asymmetry ratio calculated from the luminescence intensities of the D5(0)-->F7(2) and D5(0)-->F7(1) transition, respectively. The differences in ligand-related luminescence quenching are discussed. Based on the temperature dependence of the luminescence decay times an activation energy for the ligand-specific non-radiative deactivation in Eu(III)-2HB or Eu(III)-GL complexes was determined. It is stressed that ligand-specific quenching processes (other than OH quenching induced by water molecules) need to be determined and considered in detail, in order to extract speciation-relevant information from luminescence data (e.g., estimation of the number of water molecules n(H(2)0) in the first coordination sphere of Eu(III)). In case of 2HB, conclusions drawn from the evaluation of the Eu(III) luminescence are compared with results of a X-ray structure analysis. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Near-infrared (NIR) emitting Nd/Yb(III) complexes sensitized by MLCT states of Ru(II)/Ir(III) metalloligands in the visible light region.

    PubMed

    Zhang, Lu-Yin; Hou, Ya-Jun; Pan, Mei; Chen, Ling; Zhu, Yi-Xuan; Yin, Shao-Yun; Shao, Guang; Su, Cheng-Yong

    2015-09-14

    Four Ru(II)/Ir(III) metalloligands have been designed and synthesized from polypyridine and bibenzimidazole (BiBzIm) organic ligands, which show strong visible light absorption via metal-to-ligand charge transfer (MLCT) transitions. Nd/Yb(III) complexes were further assembled from these Ru(II)/Ir(III) metalloligands, and Ln(III)-centered NIR emissions can be efficiently sensitized by (3)MLCT states of the metalloligands in the visible-light region. The energy transfer rates for the complexes are generally in the order Nd > Yb, which is due to the better matching between (3)MLCT states of Ru(II)/Ir(III) metalloligands and densely distributed excited states of Nd(III) ions. Long decayed lifetimes on a μs scale and high quantum yields up to 1% are obtained in these lanthanide complexes, suggesting that the Ru(II)/Ir(III) metalloligands can serve as a good visible light harvesting antenna to efficiently sensitize Ln(III)-based NIR luminescence.

  16. Americium(iii) and europium(iii) complex formation with lactate at elevated temperatures studied by spectroscopy and quantum chemical calculations.

    PubMed

    Barkleit, Astrid; Kretzschmar, Jerome; Tsushima, Satoru; Acker, Margret

    2014-08-07

    Thermodynamic parameters for the complex formation of Am(iii) and Eu(iii) with lactate were determined with UV-vis and time-resolved laser-induced fluorescence spectroscopy (TRLFS) in a temperature range between 25 and 70 °C. The reaction enthalpy decreased with increasing ionic strength. ATR FT-IR and NMR spectroscopy in combination with density functional theory (DFT) calculations revealed structural details of the Eu(iii) lactate 1 : 1 complex: a chelating coordination mode of the lactate with a monodentate binding carboxylate group and the hydroxyl group being deprotonated.

  17. Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol.

    PubMed

    Kostova, Irena; Manolov, Ilia; Radulova, Maritza

    2004-06-01

    A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.

  18. Dissolution of iron(III)(HYDR)oxides by metal-EDTA-complexes

    SciTech Connect

    Nowack, B.; Sigg, L.

    1996-10-01

    The dissolution of Fe(III)(hydroxides) (goethite and hydrous ferric oxide) by metal-EDTA complexes occurs by ligand-promoted dissolution. The process is initiated by adsorption of the metal-EDTA to the surface, dissociation of the complex at the surface and release of Fe(III)EDTA into solution. The dissolution rate is decreased to a great extent if EDTA is complexed by metals in comparison to uncomplexed EDTA. The rate decreases in the order EDTA >> CaEDTA > PbEDTA > ZnEDTA > CuEDTA > Co(II)EDTA > NiEDTA. Two different rate-limiting steps determine the system: (1) detachment of Fe(III) from the oxide-structure and (2) dissociation of the metal-EDTA complexes. In the case of goethite, step (1) is more important than (2) and the difference in the dissolution rate for several metals is small. In the case of hydrous ferric oxide, step (2) is rate-limiting and the effect of the complexed metal is very pronounced.

  19. Enantioselective cleavage of supercoiled plasmid DNA catalyzed by chiral macrocyclic lanthanide(III) complexes.

    PubMed

    Krężel, Artur; Lisowski, Jerzy

    2012-02-01

    The enantiomers of the Sm (III), Eu (III) and Yb (III) complexes [LnL(NO(3))(2)](NO(3)) of a chiral hexaazamacrocycle were tested as catalysts for the hydrolytic cleavage of supercoiled plasmid DNA. The catalytic activity was remarkably enantioselective; while the [LnL(SSSS)(NO(3))(2)](NO(3)) enantiomers promoted the cleavage of plasmid pBR322 from the supercoiled form (SC) to the nicked form (NC), the [LnL(RRRR)(NO(3))(2)](NO(3)) enantiomers were inactive. Kinetics of plasmid DNA hydrolysis was also investigated by agarose electrophoresis and it indicated typical single-exponential cleavage reaction. The hydrolytic mechanism of DNA cleavage was confirmed by the successful ligation of hydrolysis product by T4 ligase. The NMR study of the solutions of the complexes in various buffers indicated that the complexes exist as monomeric cationic complexes [LnL(H(2)O)(3)](3+) in slightly acidic solutions and as dimeric cationic complexes [Ln(2)L(2)(μ-OH)(2)(H(2)O)(2)](4+) in slightly basic 8mM solutions, with the latter form being a possible catalyst for hydrolysis of phosphodiester bonds.

  20. Synthesis, spectroscopic, thermal and anticancer studies of metal-antibiotic chelations: Ca(II), Fe(III), Pd(II) and Au(III) chloramphenicol complexes

    NASA Astrophysics Data System (ADS)

    Al-Khodir, Fatima A. I.; Refat, Moamen S.

    2016-09-01

    Four Ca(II), Fe(III), Pd(II) and Au(III) complexes of chloramphenicol drug have been synthesized and well characterized using elemental analyses, (infrared, electronic, and 1H-NMR) spectra, magnetic susceptibility measurement, and thermal analyses. Infrared spectral data show that the chloramphenicol drug coordinated to Ca(II), Pd(II) and Au(III) metal ions through two hydroxyl groups with 1:1 or 1:2 M ratios, but Fe(III) ions chelated towards chloramphenicol drug via the oxygen and nitrogen atoms of amide group with 1:2 ratio based on presence of keto↔enol form. The X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques were used to identify the nano-size particles of both iron(III) and gold(III) chloramphenicol complexes. The antimicrobial assessments of the chloramphenicol complexes were scanned and collected the results against of some kind of bacteria and fungi. The cytotoxic activity of the gold(III) complex was tested against the human colon carcinoma (HCT-116) and human hepatocellular carcinoma (HepG-2) tumor cell lines.

  1. Uranium(iii) and thorium(iv) alkyl complexes as potential starting materials.

    PubMed

    Behrle, Andrew C; Myers, Alexander J; Rungthanaphatsophon, Pokpong; Lukens, Wayne W; Barnes, Charles L; Walensky, Justin R

    2016-12-13

    The synthesis and characterisation of a rare U(iii) alkyl complex, U[η(4)-Me2NC(H)C6H5]3, using the dimethylbenzylamine (DMBA) ligand has been accomplished. While attempting to prepare the U(iv) compound, reduction to the U(iii) complex occurred. In the analogous Th(iv) system, C-H bond activation of a methyl group of one dimethylamine was observed yielding Th[η(4)-Me2NC(H)C6H5]2[η(5)-(CH2)MeNC(H)C6H5] with a dianionic DMBA ligand. The utility of these complexes as starting materials has been analyzed using a bulky dithiocarboxylate ligand to yield tetravalent actinide species.

  2. Titanocene(III) complexes with 2-phosphinoaryloxide ligands for the catalytic dehydrogenation of dimethylamine borane.

    PubMed

    Klahn, Marcus; Hollmann, Dirk; Spannenberg, Anke; Brückner, Angelika; Beweries, Torsten

    2015-07-21

    A study of the dehydrogenation of dimethylamine borane using different titanocene(III) complexes with 2-phosphinoaryloxide ligands is presented. Complexes Cp2Ti(κ(2)-O, P-O-C6H4-PR2) (3a: R = i-Pr, 3b: R = Ph) (Cp = η(5)-cyclopentadienyl) and Cp*2Ti(κ(1)-O-O-C6H4-PR2) (5a: R = i-Pr, 5b: R = Ph) (Cp* = η(5)-pentamethylcyclopentadienyl) were prepared by reactions of the 2-phosphinophenol ligand with different titanocene sources and fully characterised. Their catalytic activity depends on the steric influence of the cyclopentadienyl ligand, the coordination mode of the 2-phosphinoaryloxide ligand and on the used solvent. Complex 3a showed a turnover number of 43.2 in the neat substrate after 24 hours. EPR investigations were used to elucidate the fate of the Ti(III) catalyst.

  3. Synthesis of Cr(III)-Morin Complex: Characterization and Antioxidant Study

    PubMed Central

    Panhwar, Qadeer K.; Memon, Shahabuddin

    2014-01-01

    The complex formation between Cr(III) and morin was carried out in methanol and confirmed by analytical characterization using UV-Vis, IR, 1H NMR, and TG-DTA. UV-Vis shows significant bathochromic shift in benzoyl upon coordination as well as IR well illustrates the peak shift of C=O group and formation of a O–Cr(III) bond. Likewise, 1H NMR studies clarify that Cr(III) metal ion replaces the 5OH proton hence; 5-hydroxy-4-keto site is employed by morin in chelation to form six-membered stable ring system out of three available chelating sites. In addition, TG-DTA denotes the presence of coordinated and crystalline water molecules. The melting point of the complex was found to be 389°C by DSC. In addition, Cr(III)-morin complex was found to be a more potent antioxidant than morin as evaluated by DPPH• and FRAP methods. PMID:24688439

  4. Stereoelectronic Effects in Cl2 Elimination from Binuclear Pt(III) Complexes.

    PubMed

    Powers, David C; Hwang, Seung Jun; Anderson, Bryce L; Yang, Haifeng; Zheng, Shao-Liang; Chen, Yu-Sheng; Cook, Timothy R; Gabbaï, François P; Nocera, Daniel G

    2016-11-21

    Halogen photoelimination is the critical energy-storing step of metal-catalyzed HX-splitting photocycles. Homo- and heterobimetallic Pt(III) complexes display among the highest quantum efficiencies for halogen elimination reactions. Herein, we examine in detail the mechanism and energetics of halogen elimination from a family of binuclear Pt(III) complexes featuring meridionally coordinated Pt(III) trichlorides. Transient absorption spectroscopy, steady-state photocrystallography, and far-infrared vibrational spectroscopy suggest a halogen elimination mechanism that proceeds via two sequential halogen-atom-extrusion steps. Solution-phase calorimetry experiments of the meridional complexes have defined the thermodynamics of halogen elimination, which show a decrease in the photoelimination quantum efficiency with an increase in the thermochemically defined Pt-X bond strength. Conversely, when compared to an isomeric facial Pt(III) trichloride, a much more efficient photoelimination is observed for the fac isomer than would be predicted based on thermochemistry. This difference in the fac vs mer isomer photochemistry highlights the importance of stereochemistry on halogen elimination efficiency and points to a mechanism-based strategy for achieving halogen elimination reactions that are both efficient and energy storing.

  5. Factors associated with development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics.

    PubMed

    Joffe, Daniel J; Lelewski, Roxana; Weese, J Scott; Mcgill-Worsley, Jamie; Shankel, Catharine; Mendonca, Sonia; Sager, Tara; Smith, Michael; Poljak, Zvonimir

    2016-01-01

    This study investigated the association between presence of respiratory pathogens and development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics. In total, 86 dogs were tested using a commercial PCR respiratory panel; 64 dogs were considered as cases and 22 were control dogs matched by veterinary clinic. No control animals (0/22) were positive for canine parainfluenza virus (CPIV), whereas 27/64 (42%) CIRDC cases were positive. Furthermore, 81% of case dogs tested positive for Mycoplasma cynos, compared with 73% of control dogs. Canine respiratory corona virus (CRCoV) was detected in no control dogs compared with 9.4% of clinical dogs. No animals were positive for any influenza virus type A present in the diagnostic panel. Presence of CPIV was associated (P < 0.01) with the occurrence of CIRDC after adjustment for demographic factors and presence of CRCoV (P = 0.09).

  6. Factors associated with development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics

    PubMed Central

    Joffe, Daniel J.; Lelewski, Roxana; Weese, J. Scott; Mcgill-Worsley, Jamie; Shankel, Catharine; Mendonca, Sonia; Sager, Tara; Smith, Michael; Poljak, Zvonimir

    2016-01-01

    This study investigated the association between presence of respiratory pathogens and development of Canine Infectious Respiratory Disease Complex (CIRDC) in dogs in 5 Canadian small animal clinics. In total, 86 dogs were tested using a commercial PCR respiratory panel; 64 dogs were considered as cases and 22 were control dogs matched by veterinary clinic. No control animals (0/22) were positive for canine parainfluenza virus (CPIV), whereas 27/64 (42%) CIRDC cases were positive. Furthermore, 81% of case dogs tested positive for Mycoplasma cynos, compared with 73% of control dogs. Canine respiratory corona virus (CRCoV) was detected in no control dogs compared with 9.4% of clinical dogs. No animals were positive for any influenza virus type A present in the diagnostic panel. Presence of CPIV was associated (P < 0.01) with the occurrence of CIRDC after adjustment for demographic factors and presence of CRCoV (P = 0.09). PMID:26740697

  7. Deformylation Reaction by a Nonheme Manganese(III)-Peroxo Complex via Initial Hydrogen-Atom Abstraction.

    PubMed

    Barman, Prasenjit; Upadhyay, Pranav; Faponle, Abayomi S; Kumar, Jitendra; Nag, Sayanta Sekhar; Kumar, Devesh; Sastri, Chivukula V; de Visser, Sam P

    2016-09-05

    Metal-peroxo intermediates are key species in the catalytic cycles of nonheme metalloenzymes, but their chemical properties and reactivity patterns are still poorly understood. The synthesis and characterization of a manganese(III)-peroxo complex with a pentadentate bispidine ligand system and its reactivity with aldehydes was studied. Manganese(III)-peroxo can react through hydrogen-atom abstraction reactions instead of the commonly proposed nucleophilic addition reaction. Evidence of the mechanism comes from experiments which identify a primary kinetic isotope effect of 5.4 for the deformylation reaction. Computational modeling supports the established mechanism and identifies the origin of the reactivity preference of hydrogen-atom abstraction over nucleophilic addition.

  8. Single-molecule magnetism in three related {Co(III)2Dy(III)2}-acetylacetonate complexes with multiple relaxation mechanisms.

    PubMed

    Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

    2013-06-17

    Three new heterometallic complexes with formulas of [Dy(III)2Co(III)2(OMe)2(teaH)2(acac)4(NO3)2] (1), [Dy(III)2Co(III)2(OH)2(teaH)2(acac)4(NO3)2]·4H2O (2), and [Dy(III)2Co(III)2(OMe)2(mdea)2(acac)4(NO3)2] (3) were characterized by single-crystal X-ray diffraction and by dc and ac magnetic susceptibility measurements. All three complexes have an identical "butterfly"-type metallic core that consists of two Dy(III) ions occupying the "body" position and two diamagnetic low-spin Co(III) ions occupying the outer "wing-tips". Each complex displays single-molecule magnet (SMM) behavior in zero applied magnetic field, with thermally activated anisotropy barriers of 27, 28, and 38 K above 7.5 K for 1-3, respectively, as well as observing a temperature-independent mechanism of relaxation below 5 K for 1 and 2 and at 3 K for 3, indicating fast quantum tunneling of magnetization (QTM). A second, faster thermally activated relaxation mechanism may also be active under a zero applied dc field as derived from the Cole-Cole data. Interestingly, these complexes demonstrate further relaxation modes that are strongly dependent upon the application of a static dc magnetic field. Dilution experiments that were performed on 1, in the {Y(III)2Co(III)2} diamagnetic analog, show that the slow magnetic relaxation is of a single-ion origin, but it was found that the neighboring ion also plays an important role in the overall relaxation dynamics.

  9. Synthesis and physico-chemical studies of cyclometalated heteroleptic iridium(III) complexes.

    PubMed

    Jayabharathi, Jayaraman; Thanikachalam, Venugopal; Srinivasan, Natesan; Jayamoorthy, Karunamoorthy

    2012-07-01

    Phosphorescent studies of 2-arylimidazole heteroleptic cyclometalated iridium(III) complexes with picolinic acid as the ancillary ligand were made. The observed experimental data reveals that these complexes possess dominantly (3)MLCT and (3)π-π* excited states and the solvent shift of these complexes are interpreted by Reichardt-Dimroth and Marcus solvent functions. The results are consistent with prior assignments on the absorption band to a metal-to-ligand charge transfer excited state associated with chelating ligand. Emission kinetic studies exploited that the radiative transition (k(r)), increases with increasing λ(emi). Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Solvation of Co(III)-cysteinato complexes in water: a DFT-based molecular dynamics study.

    PubMed

    Spezia, Riccardo; Bresson, Carole; Den Auwer, Christophe; Gaigeot, Marie-Pierre

    2008-05-22

    Structural, dynamical, and vibrational properties of complexes made of metal cobalt(III) coordinated to different amounts of cysteine molecules were investigated with DFT-based Car-Parrinello molecular dynamics (CPMD) simulations in liquid water solution. The systems are composed of Co(III):3Cys and Co(III):2Cys immersed in liquid water which are modeled by about 110 explicit water molecules, thus one of the biggest molecular systems studied with ab initio molecular simulations so far. In such a way, we were able to investigate structural and dynamical properties of a model of a typical metal binding site used by several proteins. Cobalt, mainly a toxicological agent, can replace the natural binding metal and thus modify the biochemical activity. The structure of the surrounding solvent around the metal-ligands complexes is reported in detail, as well as the metal-ligands coordination bonds, using radial distribution functions and electronic analyses with Mayer bond orders. Structures of the Cocysteine complexes are found in very good agreement with EXAFS experimental data, stressing the importance of considering the surrounding solvent in the modeling. A vibrational analysis is also conducted and compared to experiment, which strengthens the reliability of the solvent interactions with the Cocysteine complexes from our molecular dynamics simulations, as well as the dynamics of the systems. From this preliminary analysis, we could suggest a vibrational fingerprint able to distinguish Co(III):2Cys from Co(III):3Cys. Our simulations also show the importance of considering a quantum explicit solvent, as solute-to-solvent proton transfer events have been observed.

  11. Complexation of Lactate with Nd(III) and Eu(III) at Variable Temperatures: Studies by Potentiometry, Microcalorimetry, Optical Absorption and Luminescence Spectroscopy

    SciTech Connect

    Tian, Guoxin; Martin, Leigh R.; Rao, Linfeng

    2010-10-01

    Complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy and microcalorimetry. Stability constants of three successive lactate complexes (ML{sup 2+}, ML{sup 2+} and ML{sub 3}(aq), where M stands for Nd and Eu, and L stands for lactate) at 10, 25, 40, 55 and 70 C were determined. The enthalpies of complexation at 25 C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) with lactate is exothermic, and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated {alpha}-hydroxyl group of lactate participates in the complexation.

  12. The ins and outs of breath holding: simple demonstrations of complex respiratory physiology.

    PubMed

    Skow, Rachel J; Day, Trevor A; Fuller, Jonathan E; Bruce, Christina D; Steinback, Craig D

    2015-09-01

    The physiology of breath holding is complex, and voluntary breath-hold duration is affected by many factors, including practice, psychology, respiratory chemoreflexes, and lung stretch. In this activity, we outline a number of simple laboratory activities or classroom demonstrations that illustrate the complexity of the integrative physiology behind breath-hold duration. These activities require minimal equipment and are easily adapted to small-group demonstrations or a larger-group inquiry format where students can design a protocol and collect and analyze data from their classmates. Specifically, breath-hold duration is measured during a number of maneuvers, including after end expiration, end inspiration, voluntary prior hyperventilation, and inspired hyperoxia. Further activities illustrate the potential contribution of chemoreflexes through rebreathing and repeated rebreathing after a maximum breath hold. The outcome measures resulting from each intervention are easily visualized and plotted and can comprise a comprehensive data set to illustrate and discuss complex and integrated cardiorespiratory physiology. Copyright © 2015 The American Physiological Society.

  13. Electrogenerated chemiluminescence from heteroleptic iridium(III) complexes with multicolor emission.

    PubMed

    Zhou, Yuyang; Gao, Hongfang; Wang, Xiaomei; Qi, Honglan

    2015-02-16

    Electrogenerated chemiluminescence (ECL) with different emission colors is important in the development of multichannel analytical techniques. In this report, five new heteroleptic iridium(III) complexes were synthesized, and their photophysical, electrochemical, and ECL properties were studied. Here, 2-(2,4-difluorophenyl)pyridine (dfppy, complex 1), 2-phenylbenzo[d]thiazole (bt, complex 2), and 2-phenylpyridine (ppy, complex 3) were used as the main ligands to tune the emission color, while avobenzone (avo) was used as the ancillary ligand. For comparison, complexes 4 and 5 with 2-phenylpyridine and 2-phenylbenzo[d]thiazole as the main ligand, respectively, and acetyl acetone (acac) as the ancillary ligand were also synthesized. All five iridium(III) complexes had strong intraligand absorption bands (π–π*) in the UV region (below 350 nm) and a featureless MLCT (d−π*) transition in the visible 400–500 nm range. Multicolored emissions were observed for these five iridium(III) complexes, including green, orange, and red for complexes 4, 5, 2, 1, 3, respectively. Density functional theory calculations indicate that the electronic density of the highest occupied molecular orbital is entirely located on the C^N ligands and the iridium atom, while the formation of the lowest unoccupied molecular orbital (LUMO) is complicated. The LUMO is mainly assigned to the ancillary ligand for complexes 1 and 3 but to the C^N ligand for complexes 2, 4, and 5. Cyclic voltammetry studies showed that all these complexes have a reversible oxidation wave, but no reduction waves were found in the electrochemical windows of CH2Cl2. The E1/2(ox) values of these complexes ranged from 0.642 to 0.978 V for complexes 3, 4, 2, 5, 1, (in increasing order) and are all lower than that of Ru(bpy)3(2+). Most importantly, when using tripropylamine as a coreactant, complexes 1–5 exhibited intense ECL signals with an emission wavelength centered at 616, 580, 663, 536, and 569 nm, respectively

  14. Synthesis, structural characterization and photoluminescence properties of a novel La(III) complex

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Ceyhan, Gökhan; Atcı, Emine; McKee, Vickie; Tümer, Mehmet

    2015-05-01

    In this study, a novel La(III) complex [La(H2L)2(NO3)3(MeOH)] of a Schiff base ligand was synthesized and characterized by spectroscopic and analytical methods. Single crystals of the complex suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a MeOH solution of the complex which was found to crystallise as [La(H2L)2(NO3)3(MeOH)]ṡ2MeOHṡH2O. The structure was solved in monoclinic crystal system, P21/n space group with unit cell parameters a = 10.5641(11), b = 12.6661(16), c = 16.0022(17) Å, α = 67.364(2), β = 83.794(2)°, γ = 70.541(2)°, V = 1862.9(4) Å3 and Z = 2 with R final value of 0.526. In the complex, the La(III) ion is ten-coordinated by O atoms, five of which come from three nitrate ions, four from the two Schiff base ligands and one from MeOH oxygen atom. The Schiff base ligands in the structure are in a zwitter ion form with the phenolic H transferred to the imine N atom. Thermal properties of the La(III) complex were examined by thermogravimetric analysis and the complex was found to be thermally stable up to 310 °C. The Schiff base ligand and its La(II) complex were screened for their in vitro antimicrobial activity against Bacillus megaterium, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus (Gram positive bacteria), Klebsiella pneumonia, Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa (Gram negative bacteria), Candida albicans,Yarrowia lipolytica (fungus) and Saccharomyces cerevisiae (yeast). The complex shows more antimicrobial activity than the free ligand.

  15. Anion responsive Europium (III) complexes for Optical Sensing and PARACEST MRI

    NASA Astrophysics Data System (ADS)

    Buttarazzi, Leandro Alfredo

    The Eu(III) complexes of 1-(acetyl-7-Methyl-4-(trifluoromethyl) quinolin-2(1H)-one)4,7,10 tris(2-hydroxypropyl)-1,4,7,10-tetraazacycladodecane (Eu(S-THPC)3+ ) and 1-(acetyl-dioctadecylamine)4,7,10 tris(hydroxypropyl)-1,4,7,10-tetraazacycladodecane (Eu(S-THMC)3+) were studied in order to develop complexes that are both optical sensors and MRI contrast agents that respond to biologically relevant anions. Both complexes are related to Eu(S-THP) where S-THP = (1S,4S,7S,10S)-1,4,7,10-tetrakis(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane. Eu(III) excitation, emission and time resolved luminescence spectroscopy experiments were used to study binding of the anions. One complex, Eu(THPC)3+ has an appended carbostyril dye for sensitization of Eu(III) luminescence. Luminescence experiments were done on this complex in order to quantify the effectiveness of the energy transfer from the dye to the lanthanide and to obtain binding constants of the anions from the Eu(III) emission peaks. Emission spectra were obtained by exciting the chromophore at 340 nm. Our results suggest that phosphate binds with a dissociation constant (Kd) of 4.2mM and citrate binds with a Kd of 228 uM. The quantum yield for the complex was low compared to other reported complexes in literature. Eu(S-THMC) 3+, and Eu(S-THMAC)3+ containing long carbon chains for incorporation into liposomes were explored as an approach to develop complexes with increased sensitivity as CEST agents. CEST experiments with the complex incorporated into a liposome and as a micelle were carried out. Liposome formation was achieved but no CEST effect was observed with two different lanthanide complexes. Eu(S-THMC)3+ gave the most promising results by showing CEST in acetonitrile and 50/50 acetonitrile/H 2O. However further experiments with this complex in buffered aqueous solution failed. Yb(S-THMAC)3+ solubility was poor in both acetonitrile and in water and this likely prevented the observation of CEST spectra.

  16. Novel reduction of Cr(VI) from wastewater using a naturally derived microcapsule loaded with rutin-Cr(III) complex.

    PubMed

    Qi, Yun; Jiang, Meng; Cui, Yuan-Lu; Zhao, Lin; Liu, Shejiang

    2015-03-21

    The harmfulness of carcinogenic hexavalent chromium (Cr(VI)) is dramatically decreased when Cr(VI) is reduced to trivalent chromium (Cr(III)). Rutin, a natural flavonoid, exhibits excellent antioxidant activity by coordinating metal ions. In this study, a complex containing rutin and Cr(III) (rutin-Cr(III)) was synthesized and characterized. The rutin-Cr(III) complex was much easier to reduce than rutin. The reduction of the rutin-Cr(III) complex was highly pH-dependent, with 90% of the Cr(VI) being reduced to Cr(III) in 2h under optimal conditions. A biodegradable, sustained-release system encapsulating the rutin-Cr(III) complex in a alginate-chitosan microcapsule (rutin-Cr(III) ACMS) was also evaluated, and the reduction of Cr(VI) was assessed. This study also demonstrated that low-pH solutions increased the reduction rate of Cr(VI). The environmentally friendly microcapsules can reduce Cr(VI) for prolonged periods of time and can easily biodegrade after releasing the rutin-Cr(III) complex. Given the excellent performance of rutin-Cr(III) ACMS, the microcapsule system represents an effective system for the remediation of Cr(VI) pollution.

  17. Treacher Collins syndrome mutations in Saccharomyces cerevisiae destabilizes RNA polymerase I and III complex integrity.

    PubMed

    Walker-Kopp, Nancy; Jackobel, Ashleigh J; Pannafino, Gianno N; Morocho, Paola A; Xu, Xia; Knutson, Bruce A

    2017-08-14

    Treacher Collins syndrome (TCS) is a craniofacial disorder that is characterized by the malformation of the facial bones. Mutations in three genes (TCOF1, POLR1C, and POLR1D) involved in RNA polymerase I (Pol I) transcription account for more than 90% of disease cases. Two of these TCS-associated genes, POLR1C and POLR1D, encode for essential Pol I/III subunits that form a heterodimer necessary for Pol I/III assembly, and many TCS mutations lie along their evolutionarily conserved dimerization interface. Here we elucidate the molecular basis of TCS mutations in S. cerevisiae, and present a new model for how TCS mutations may disrupt Pol I and III complex integrity. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Synthesis, Structural and Spectroscopic Characterization, and Reactivities of Mononuclear Cobalt(III)-Peroxo Complexes

    PubMed Central

    Cho, Jaeheung; Sarangi, Ritimukta; Kang, Hye Yeon; Lee, Jung Yoon; Kubo, Minoru; Ogura, Takashi; Solomon, Edward I.; Nam, Wonwoo

    2010-01-01

    Metal-dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)- peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+, were synthesized by reacting [Co(12-TMC)(CH3CN)]2+ and [Co(13-TMC)(CH3CN)]2+, respectively, with H2O2 in the presence of triethylamine. The mononuclear cobalt(III)-peroxo intermediates were isolated and characterized by various spectroscopic techniques and X-ray crystallography, and the structural and spectroscopic characterization demonstrated unambiguously that the peroxo ligand is bound in a side-on η2 fashion. The O-O bond stretching frequency of [Co(12-TMC)(O2)]+ and [Co(13- TMC)(O2)]+ was determined to be 902 cm−1 by resonance Raman spectroscopy. The structural properties of the CoO2 core in both complexes are nearly identical; the O-O bond distances of [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+ were 1.4389(17) Å and 1.438(6) Å, respectively. The cobalt(III)-peroxo complexes showed reactivities in the oxidation of aldehydes and O2-transfer reactions. In the aldehyde oxidation reactions, the nucleophilic reactivity of the cobalt-peroxo complexes was significantly dependent on the ring size of the macrocyclic ligands, with the reactivity of [Co(13-TMC)(O2)]+ > [Co(12-TMC)(O2)]+. In the O2-transfer reactions, the cobalt(III)-peroxo complexes transferred the bound peroxo group to a manganese(II) complex, affording the corresponding cobalt(II) and manganese(III)- peroxo complexes. The reactivity of the cobalt-peroxo complexes in O2-transfer was also significantly dependent on the ring size of tetraazamacrocycles, and the reactivity order in the O2-transfer reactions was the same as that observed in the aldehyde oxidation reactions. PMID:21062059

  19. Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies

    NASA Astrophysics Data System (ADS)

    Priya, N. Padma; Arunachalam, S.; Manimaran, A.; Muthupriya, D.; Jayabalakrishnan, C.

    2009-04-01

    An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl-aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

  20. 17O NMR study of diamagnetic and paramagnetic lanthanide(III)-DOTA complexes in aqueous solution.

    PubMed

    Fusaro, Luca; Luhmer, Michel

    2014-08-18

    The complexes between the polyaminocarboxylate DOTA ligand and the whole series of stable lanthanide(III) metal ions, except Gd(3+), were studied in aqueous solution by (17)O NMR. For all of the paramagnetic systems, the (17)O NMR signals of both the nonchelating (O1) and chelating (O2) oxygen atoms could be detected, and for some of them, the signals of both the SAP and TSAP (TSAP') conformational isomers were also observed. Line width data analysis reveals that signal broadening is not dominated by paramagnetic relaxation enhancement, as it was believed to be. The data indicate that quadrupole relaxation and, for some complexes, chemical exchange between the SAP and TSAP isomers are the major contributions to the (17)O NMR line width at 25 °C. Besides, the Fermi contact and pseudocontact contributions to the observed lanthanide-induced shifts could be extracted. The (17)O hyperfine coupling constants determined for O2 in the SAP and TSAP isomers are similar to each other and to the values reported for several Gd(III) complexes comprising fast-exchanging ligands. Interestingly, the results suggest that (17)O NMR should prove to be useful for the study of highly paramagnetic Gd(III) complexes of nonlabile ligands.

  1. Innovative magnetic resonance imaging diagnostic agents based on paramagnetic Gd(III) complexes.

    PubMed

    Aime, Silvio; Dastrù, Walter; Crich, Simonetta Geninatti; Gianolio, Eliana; Mainero, Valentina

    2002-01-01

    Gd(III) complexes are under intense scrutiny as contrast agents for magnetic resonance imaging (MRI). They act by enhancing tissutal proton relaxation rates. Much has already been done in order to get an in-depth understanding of the relationships between structure, dynamics, and contrastographic ability of these paramagnetic complexes. Their potential in the assessment of flow, perfusion, and capillary permeability has already been established. The next challenges are in the field of molecular imaging applications, which would allow the attainment of early diagnosis based on the recognition of specific reporters of the onset of the pathological state. To this end, Gd(III) complexes have to be endowed with improved targeting capabilities by conjugating suitable recognition synthons on their surfaces. Small peptides are candidates of choice for the attainment of this goal. Moreover, the intrinsic low sensitivity of the NMR techniques implies the need to deliver large amounts of contrast agents to the target in order to get its visualization in the resulting images. Highly efficient delivery systems have been identified, which bring a great promise for the development of innovative diagnostic agents based on Gd(III) complexes.

  2. Novel Ru(III) Complexes with Some Benzothiazole Derivatives: Synthesis, Physicochemical and Pharmacological Investigations.

    PubMed

    Nikolova, A; Momekov, G; Bakalova, A; Nikolova, K; Ivanov, D

    2015-06-01

    In this work we present 3 new complexes of Ruthenium (III) with a general formula HL[Ru(L)2Cl4], where L=benzothiazole, 2-methylbenzothiazole and 2-mercaptobenzothiazole. The syntheses were carried out in polar medium under argon. The compounds obtained were characterised by IR-, (1)H-NMR- (13)C-NMR-, UV-VIS-spectroscopy and conductivity measurements. The ligands behaved as monodentate, bounding Ru(III) through the nitrogen atoms from the heterocycle. The cytotoxicity of the new complexes was tested against 2 human leukemic cell lines (K-562 and KE-37), using the MTT-dye reduction assay. The Ru(III) coordination compound with 2-methylbenzothiazole displayed superior activity compared to the other novel complexes. Its IC50 values were comparable to that of the reference cytotoxic drug cisplatin. In general, the ligands displayed only marginal inhibitory effects on the human leukemic cell lines. Moreover, the ability of the complexes to trigger apoptosis was evaluated using a commercially available DNA-fragmentation ELISA kit and the obtained data indicated that their proapoptotic effects well correlate to the MTT-bioassay data.

  3. Thermodynamic stability, kinetic inertness and relaxometric properties of monoamide derivatives of lanthanide(III) DOTA complexes.

    PubMed

    Tei, Lorenzo; Baranyai, Zsolt; Gaino, Luca; Forgács, Attila; Vágner, Adrienn; Botta, Mauro

    2015-03-28

    A complete thermodynamic and kinetic solution study on lanthanide(III) complexes with monoacetamide (DOTAMA, L1) and monopropionamide (DOTAMAP, L2) derivatives of DOTA (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) was undertaken with the aim to elucidate their stability and inertness in aqueous media. The stability constants of GdL1 and GdL2 are comparable, whereas a more marked difference is found in the kinetic inertness of the two complexes. The formation of the Eu(III) and Ce(III) complexes takes place via the formation of the protonated intermediates which can deprotonate and transform into the final complex through a OH(-) assisted pathway. GdL2 shows faster rates of acid catalysed decomplexation with respect to GdL1, which has a kinetic inertness comparable to GdDOTA. Nevertheless, GdL2 is one order of magnitude more inert than GdDO3A. A novel DOTAMAP-based bifunctional chelating ligand and its deoxycholic acid derivative (L5) were also synthesized. Since the coordinated water molecule in GdL2 is characterized by an exchange rate ca. two orders of magnitude greater than in GdL1, the relaxivity of the macromolecular derivatives of L5 should not be limited by the slow water exchange process. The relaxometric properties of the supramolecular adduct of GdL5 with human serum albumin (HSA) were investigated in aqueous solution by measuring the magnetic field dependence of the (1)H relaxivity which, at 20 MHz and 298 K, shows a 430% increase over that of the unbound GdL5 chelate. Thus, Gd(III) complexes with DOTAMAP macrocyclic ligands can represent good candidates for the development of stable and highly effective bioconjugate systems for molecular imaging applications.

  4. Photodegradation of hexabromocyclododecane (HBCD) by Fe(III) complexes/H2O 2 under simulated sunlight.

    PubMed

    Zhou, Danna; Wu, Yao; Feng, Xiaonan; Chen, Yong; Wang, Zongping; Tao, Tao; Wei, Dongbin

    2014-05-01

    Hexabromocyclododecane (HBCD) is a globally produced brominated flame retardant used primarily as an additive flame retardant in polystyrene and textile products. Photodegradation of HBCD in the presence of Fe(III)-carboxylate complexes/H2O2 was investigated under simulated sunlight. The degradation of HBCD decreased with increasing pH in the Fe(III)-oxalate solutions. In contrast, the optimum pH was 5.0 for the Fe(III)-citrate-catalyzed photodegradation within the range of 3.0 to 7.0. For both Fe(III)-oxalate and Fe(III)-citrate complexes, the increase of carboxylate concentrations facilitated the photodegradation. The photochemical removal of HBCD was related to the photoreactivity and speciation distribution of Fe(III) complexes. The addition of H2O2 markedly accelerated the degradation of HBCD in the presence of Fe(III)-citrate complexes. The quenching experiments showed that ·OH was responsible for the photodegradation of HBCD in the Fe(III)-carboxylate complexes/H2O2 solutions. The results suggest that Fe(III) complexes/H2O2 catalysis is a potential method for the removal of HBCD in the aqueous solutions.

  5. Carbohydrate-appended tumor targeting iron(III) complexes showing photocytotoxicity in red light.

    PubMed

    Basu, Uttara; Khan, Imran; Hussain, Akhtar; Gole, Bappaditya; Kondaiah, Paturu; Chakravarty, Akhil R

    2014-02-17

    Glucose-appended photocytotoxic iron(III) complexes of a tridentate Schiff base phenolate ligand [Fe(bpyag)(L)](NO3) (1-3), where bpyag is N,N-bis(2-pyridylmethyl)-2-aminoethyl-β-D-glucopyranoside and H2L is 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (H2phap) in 1, 3-(2-hydroxyphenylimino)-9-anthrylbutan-1-one (H2anap) in 2, and 3-(2-hydroxyphenylimino)-1-pyrenylbutan-1-one (H2pyap) in 3, were synthesized and characterized. The complex [Fe(dpma)(anap)](NO3) (4), having bis-(2-pyridylmethyl)benzylamine (dpma), in which the glucose moiety of bpyag is substituted by a phenyl group, was used as a control, and the complex [Fe(dpma)(anap)](PF6) (4a) was structurally characterized by X-ray crystallography. The structure shows a FeN4O2 core in a distorted octahedral geometry. The high-spin iron(III) complexes with magnetic moment value of ∼5.9 μB showed a low-energy phenolate-to-Fe(III) charge-transfer (CT) absorption band as a shoulder near 500 nm with a tail extending to 700 nm and an irreversible Fe(III)-Fe(II) redox couple near -0.6 V versus saturated calomel electrode. The complexes are avid binders to calf thymus DNA and showed photocleavage of supercoiled pUC19 DNA in red (647 nm) and green (532 nm) light. Complexes 2 and 3 displayed significant photocytotoxicity in red light, with an IC50 value of ∼20 μM in HeLa and HaCaT cells, and no significant toxicity in dark. The cell death is via an apoptotic pathway, by generation of reactive oxygen species. Preferential internalization of the carbohydrate-appended complexes 2 and 3 was evidenced in HeLa cells as compared to the control complex 4. A 5-fold increase in the cellular uptake was observed for the active complexes in HeLa cells. The photophysical properties of the complexes are rationalized from the density functional theory calculations.

  6. Lanthanide(III) Complexes of Tripodal N-Donor Ligands: Structural Models for the Species Involved in Solvent Extraction of Actinides(III).

    PubMed

    Wietzke, Raphaël; Mazzanti, Marinella; Latour, Jean-Marc; Pécaut, Jacques; Cordier, Pierre-Yves; Madic, Charles

    1998-12-28

    The complexation of lanthanides(III) by the tripodal ligands tpa (tris[(2-pyridyl)methyl]amine) and tpza (tris[(2-pyrazinyl)methyl]amine) has been investigated by solution NMR studies and by X-ray crystallography. The crystallographic studies show that both tpa and the new ligand tpza form complexes with a 1:1 metal:ligand ratio in which the tripodal amine acts as a tetradentate ligand. For the tpa complexes the remaining coordination sites are occupied by chloride counterions to give 7-coordination (Eu, Tb, Lu) or by chloride counterions and a methanol molecule to give 8-coordination (Nd). In [Nd(tpza)(H(2)O)(3)(CH(3)CN)(3)](ClO(4))(3).3H(2)O the remaining coordination sites are occupied by water and acetonitrile molecules to give 10-coordination while the perchlorate counterions remain non coordinating. Tpza complexes have been isolated from acetonitrile solution and dissociate completely in methanol, while the complexes of the more basic tpa can be isolated from methanol and exist in water in equilibrium with the free ligand. Solvent extraction studies of lanthanides(III) and actinides(III) from nitric acid solutions show that the new ligand tpza is, unlike tpa, a selective complexant of actinides(III). Considering their structural analogy, this difference could be explained in terms of the electronic differences between the two ligands resulting in a stronger affinity of actinides(III) for the softer donor tpza.

  7. Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems

    SciTech Connect

    Lumetta, Gregg J.; Sinkov, Sergey I.; Krause, Jeanette A.; Sweet, Lucas E.

    2016-01-27

    The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO– anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di-(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.

  8. High-spin chloro mononuclear MnIII complexes: a multifrequency high-field EPR study.

    PubMed

    Mantel, Claire; Chen, Hongyu; Crabtree, Robert H; Brudvig, Gary W; Pécaut, Jacques; Collomb, Marie-Noëlle; Duboc, Carole

    2005-03-01

    The isolation, structural characterization, and electronic properties of two six-coordinated chloromanganese (III) complexes, [Mn(terpy)(Cl)3] (1) and [Mn(Phterpy)(Cl)3] (2), are reported (terpy = 2,2':6'2"-terpyridine, Phterpy = 4'-phenyl-2,2':6',2"-terpyridine). These complexes complement a series of mononuclear azide and fluoride Mn(lll) complexes synthesized with neutral N-tridentate ligands, [Mn(L)(X)3] (X = F- or N3 and L = terpy or bpea [N,N-bis(2-pyridylmethyl)-ethylamine)], previously described. Similar to these previous complexes, 1 and 2 exhibit a Jahn-Teller distortion of the octahedron, characteristic of a high-spin Mn(III) complex (S = 2). The analysis of the crystallographic data shows that, in both cases, the manganese ion lies in the center of a distorted octahedron characterized by an elongation along the tetragonal axis. Their electronic properties were investigated by multifrequency EPR (190-475 GHz) performed in the solid state at different temperatures (5-15 K). This study confirms our previous results and further shows that: i) the sign of D is correlated with the nature of the tetragonal distortion; ii) the magnitude of D is not sensitive to the nature of the anions in our series of rhombic complexes, contrary to the porphyrinic systems; iii) the [E/D] values (0.124 for 1 and 0.085 for 2) are smaller compared to those found for the [Mn(L)(X)3] complexes (in the range of 0.146 to 0.234); and iv) the E term increases when the ligand-field strength of the equatorial ligands decreases.

  9. Biotin-conjugated tumour-targeting photocytotoxic iron(III) complexes.

    PubMed

    Saha, Sounik; Majumdar, Ritankar; Hussain, Akhtar; Dighe, Rajan R; Chakravarty, Akhil R

    2013-07-28

    Iron(III) complexes [FeL(B)] (1-4) of a tetradentate phenolate-based ligand (H3L) and biotin-conjugated dipyridophenazine bases (B), viz. 7-aminodipyrido [3,2-a:2',3'-c]-phenazine (dppza in 1), (N-dipyrido[3,2-a:2',3'-c]-phenazino)amidobiotin (dppzNB in 2), dipyrido [3,2-a:2',3'-c]-phenazine-11-carboxylic acid (dppzc in 3) and 2-((2-biotinamido)ethyl) amido-dipyrido[3,2-a:2',3'-c]-phenazine (dppzCB in 4) are prepared, characterized and their interaction with streptavidin and DNA and their photocytotoxicity and cellular uptake in various cells studied. The high-spin iron(III) complexes display Fe(III)/Fe(II) redox couple near -0.7 V versus saturated calomel electrode in dimethyl sulfoxide-0.1 M tetrabutylammonium perchlorate. The complexes show non-specific interaction with DNA as determined from the binding studies. Complexes with appended biotin moiety show similar binding to streptavidin as that of free biotin, suggesting biotin conjugation to dppz does not cause any loss in its binding affinity to streptavidin. The photocytotoxicity of the complexes is tested in HepG2, HeLa and HEK293 cell lines. Complex 2 shows higher photocytotoxicity in HepG2 cells than in HeLa or HEK293, forming reactive oxygen species. This effect is attributed to the presence of overexpressed sodium-dependent multi-vitamin transporters in HepG2 cells. Microscopic studies in HepG2 cells show internalization of the biotin complexes 2 and 4 essentially occurring by receptor-mediated endocytosis, which is similar to that of native biotin and biotin fluorescein isothiocyanate conjugate.

  10. Cyclometalated iridium(III)-guanidinium complexes as mitochondria-targeted anticancer agents.

    PubMed

    Song, Xing-Dong; Kong, Xia; He, Shu-Fen; Chen, Jia-Xi; Sun, Jing; Chen, Bing-Bing; Zhao, Jin-Wu; Mao, Zong-Wan

    2017-09-29

    Guanidinium-functionalized molecules are commonly studied for their use as pharmaceutically active compounds and drugs carriers. Herein, four cyclometalated iridium(III) complexes containing guanidinium ligands have been synthesized and characterized as potential anticancer agents. These complexes exhibit moderate antitumor activity in HeLa, MCF-7, HepG2, CNE-2, and A549 human tumor cells. Interestingly, all complexes showed higher cytotoxicity than cisplatin against a cisplatin-resistant cell line A549R, and less cytotoxicity on the nontumorigenic LO2 cells. Intracellular distribution studies suggest that these complexes are selectively localized in the mitochondria. Mechanism studies indicate that these complexes arrested the cell cycle in the G0/G1 phase and can influence mitochondrial integrity, inducing cancer cell death through reactive oxygen species (ROS)-dependent pathways. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  11. Synthesis, characterization and biodistribution of tris(beta-diketonato)technetium(III) complexes.

    PubMed

    Leesmeister, K; Schwochau, K

    1992-01-01

    New tris(beta-diketonato) complexes of trivalent 99Tc/99mTc with the ligands hexane-2,4-dione, heptane-2,4-dione, heptane-3,5-dione, and octane-3,5-dione were synthesized by reduction of pertechnetate with dithionite in the presence of excess beta-diketone. The complexes were purified by HPLC, identified by elemental analysis and FAB mass spectrometry, and characterized by vis./u.v./i.r. spectrophotometry. The hexane-2,4-dionato complex crystallizes in the monoclinic space group P21/c, isostructurally with pentane-2,4-dionatotechnetium(III). Biodistribution measurements in mice showed the neutral and lipophilic 99mTc-diketonato complexes to penetrate the blood-brain barrier. However, increasing lipophilicity decreased the brain uptake except for the heptane-2,4-dionato complex, which displayed the highest uptake of 0.82% injected dose/g.

  12. Potent anticancer activity of photo-activated oxo-bridged diiron(III) complexes.

    PubMed

    Chanu, S Binita; Banerjee, Samya; Roy, Mithun

    2017-01-05

    Cancer-specific anticancer drugs are still an elusive goal. Using light as the temporal control to generate cytotoxic species from photo-activated prodrug in the presence or absence of molecular oxygen has shown potential application targeted chemotherapy as in photodynamic therapy (PDT). In the present work we explored the chemistry of several photo-active (μ-oxo)diiron(III) complexes of the following formulation [{Fe(μ-O) (L-his)(B)}2](ClO4)2 (1a-1c), [Fe2(μ-O)(H2O)2B4](ClO4)4 (2b, 2c) and [Fe2(μ-O)(μ-O2CMe)B4](ClO4)3 (3b, 3c), L-his = l-histidine, B is 2,2'-bipyridine, 1,10-phenanthroline (phen) and dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) complexes for tumor-specific anticancer activity. Facile redox chemistry and photochemical aspects of the complexes prompted us to investigate the cytotoxic as well as the photo-activated cytotoxic properties of the complexes to the cancer cells. In the present investigation we explored the cancer-specific condition of excess concentration of H2O2 for our approach to targeted chemotherapy. Cytotoxic effect of the complexes to the cancer cells was found to be significantly higher than in normal cells indicating tumor-specific anticancer activity of the complexes. Cytotoxic effect was even more pronounced when the cancer cells treated with the complexes were exposed to the visible light (400-700 nm). There was >12 fold increase in cytotoxicity of the photoactivated complexes in cancer cells (MCF-7) in comparison to the normal cells (MCF-10a). We have defined a factor viz. cancer cell specificity factor (f) describing the targeted photochemotherapeutic effect of the complexes at their specific concentration. The factor (f) > 1 indicated the cancer cell specificity of the complexes, while f > 2.5 for the complexes under the visible light exposure suggested photodynamic effect. DCFDA assay indicated the presence of excess of ROS in the treated HeLa cells. ROS concentration was found to increase even more on visible

  13. Dysprosium(III)-diethylenetriaminepentaacetate complexes of aminocyclodextrins as chiral NMR shift reagents.

    PubMed

    Wenzel, T J; Miles, R D; Zomlefer, K; Frederique, D E; Roan, M A; Troughton, J S; Pond, B V; Colby, A L

    2000-01-01

    A metal chelating ligand is bonded to alpha-, beta-, and gamma-cyclodextrin by the reaction of diethylenetraminepentaacetic dianhydride with the corresponding 6-mono- and 2-mono(amine)cyclodextrin. Adding Dy(III) to the cyclodextrin derivatives causes shifts in the (1)H-NMR spectra of substrates such as propranolol, tryptophan, aspartame, carbinoxamine, pheniramine, doxylamine, and 1-anilino-8-naphthalenesulfonate. The Dy(III)-induced shifts enhance the enantiomeric resolution in the NMR spectra of several substrates. Enhancements in enantiomeric resolution using cyclodextrin derivatives with the amine tether are compared to previously described compounds in which the chelating ligand is attached through an ethylenediamine tether. In general, the Dy(III) complex of the 6-beta-derivative with the amine tether is a more effective chiral resolving agent than the complex with the ethylenediamine tether. The opposite trend is observed with the 2-beta-derivatives. The presence of the chelating ligand in the 2-beta-derivative hinders certain substrates from entering the cavity. For cationic substrates, evidence suggests that a cooperative association involving inclusion in the cavity and association with the Dy(III) unit occurs. Enhancements in enantiomeric resolution in the spectrum of tryptophan are greater for the secondary alpha- and gamma-derivatives than the beta-derivative.

  14. Architecture of TFIIIC and its role in RNA polymerase III pre-initiation complex assembly

    NASA Astrophysics Data System (ADS)

    Male, Gary; von Appen, Alexander; Glatt, Sebastian; Taylor, Nicholas M. I.; Cristovao, Michele; Groetsch, Helga; Beck, Martin; Müller, Christoph W.

    2015-06-01

    In eukaryotes, RNA Polymerase III (Pol III) is specifically responsible for transcribing genes encoding tRNAs and other short non-coding RNAs. The recruitment of Pol III to tRNA-encoding genes requires the transcription factors (TF) IIIB and IIIC. TFIIIC has been described as a conserved, multi-subunit protein complex composed of two subcomplexes, called τA and τB. How these two subcomplexes are linked and how their interaction affects the formation of the Pol III pre-initiation complex (PIC) is poorly understood. Here we use chemical crosslinking mass spectrometry and determine the molecular architecture of TFIIIC. We further report the crystal structure of the essential TPR array from τA subunit τ131 and characterize its interaction with a central region of τB subunit τ138. The identified τ131-τ138 interacting region is essential in vivo and overlaps with TFIIIB-binding sites, revealing a crucial interaction platform for the regulation of tRNA transcription initiation.

  15. The CA domain of the respiratory complex I is required for normal embryogenesis in Arabidopsis thaliana.

    PubMed

    Córdoba, Juan Pablo; Marchetti, Fernanda; Soto, Débora; Martin, María Victoria; Pagnussat, Gabriela Carolina; Zabaleta, Eduardo

    2016-03-01

    The NADH-ubiquinone oxidoreductase [complex I (CI), EC 1.6.5.3] of the mitochondrial respiratory chain is the principal entry point of electrons, and vital in maintaining metabolism and the redox balance. In a variety of eukaryotic organisms, except animal and fungi (Opisthokonta), it contains an extra domain composed of putative gamma carbonic anhydrases subunits, named the CA domain, which was proposed to be essential for complex I assembly. There are two kinds of carbonic anhydrase subunits: CAs (of which there are three) and carbonic anhydrase-like proteins (CALs) (of which there are two). In plants, the CA domain has been linked to photorespiration. In this work, we report that Arabidopsis mutant plants affected in two specific CA subunits show a lethal phenotype. Double homozygous knockouts ca1ca2 embryos show a significant developmental delay compared to the non-homozygous embryos, which show a wild-type (WT) phenotype in the same silique. Mutant embryos show impaired mitochondrial membrane potential and mitochondrial reactive oxygen species (ROS) accumulation. The characteristic embryo greening does not take place and fewer but larger oil bodies are present. Although seeds look dark brown and wrinkled, they are able to germinate 12 d later than WT seeds. However, they die immediately, most likely due to oxidative stress.Since the CA domain is required for complex I biogenesis, it is predicted that in ca1ca2 mutants no complex I could be formed, triggering the lethal phenotype. The in vivo composition of a functional CA domain is proposed.

  16. Deciphering upper respiratory tract microbiota complexity in healthy calves and calves that develop respiratory disease using shotgun metagenomics.

    PubMed

    Gaeta, Natália C; Lima, Svetlana F; Teixeira, Andre G; Ganda, Erika K; Oikonomou, Georgios; Gregory, Lilian; Bicalho, Rodrigo C

    2017-02-01

    Bovine respiratory disease (BRD) is a multifactorial disorder responsible for severe economic losses in dairy and feedlot herds. Advances in next-generation sequencing mean that microbial communities in clinical samples, including non-culturable bacteria, can be characterized. Our aim was to evaluate the microbiota of the upper respiratory tract of healthy calves and calves with BRD using whole-genome sequencing (shotgun metagenomics). We performed deep nasopharyngeal swabs on 16 Holstein heifer calves (10 healthy and 6 diagnosed with BRD during the study) at 14 and 28 d of life in 1 dairy herd near Ithaca, New York. Total DNA was extracted, and whole-genome sequencing was performed using the MiSeq Illumina platform (Illumina Inc., San Diego, CA). Samples included 5 predominant phyla: Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Tenericutes. At the genus level, we observed differences between groups for Pseudomonas spp. At the species level, Mannheimia haemolytica was the most abundant bacterium detected. We detected significant differences between groups of calves in the relative abundance of Pseudomonas fluorescens. Pasteurella multocida was among the 20 most abundant species, and Moraxella catarrhalis, commonly associated with pneumonia in humans, was detected in all groups. Analysis of resistance to antibiotics and compounds profiling revealed differences in cobalt-zinc-cadmium resistance. Further research to elucidate the role of Moraxella catarrhalis in BRD is warranted. Genes that were resistant to cobalt-zinc-cadmium, observed mostly in calves with BRD, might be associated with difficulties in antibiotic treatment. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  17. Synthesis, characterization and antibacterial studies of ruthenium(III) complexes derived from chitosan schiff base.

    PubMed

    Vadivel, T; Dhamodaran, M

    2016-09-01

    Chitosan can be modified chemically by condensation reaction of deacetylated chitosan with aldehyde in homogeneous phase. This condensation is carried by primary amine (NH2) with aldehyde (CHO) to form corresponding schiff base. The chitosan biopolymer schiff base derivatives are synthesized with substituted aldehydes namely 4-hydroxy-3-methoxy benzaldehyde, 2-hydroxy benzaldehyde, and 2-hydroxy-3-methoxy benzaldehyde, becomes a complexing agent or ligand. The Ruthenium(III) complexes were obtained by complexation of Ruthenium with schiff base ligands and this product exhibits as an excellent solubility and more biocompatibility. The novel series of schiff base Ruthenium(III) complexes are characterized by Elemental analysis, FT-IR spectroscopy, and Thermo-gravimetric analysis (TGA). The synthesized complexes have been subjected to antibacterial study. The antibacterial results indicated that the antibacterial activity of the complexes were more effective against Gram positive and Gram negative pathogenic bacteria. These findings are giving suitable support for developing new antibacterial agent and expand our scope for applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Colorimetric and luminescent bifunctional iridium(III) complexes for the sensitive recognition of cyanide ions

    NASA Astrophysics Data System (ADS)

    Chen, Xiudan; Wang, Huili; Li, Jing; Hu, Wenqin; Li, Mei-Jin

    2017-02-01

    Two new cyclometalated iridium(III) complexes [(ppy)2Irppz]Cl (1) and [(ppy)2Irbppz]Cl (2) (where ppy = 2-phenylpyridine, ppz = 4,7-phenanthrolino-5,6:5,6-pyrazine, bppz = 2.3-di-2-pyridylpyrazine), were designed and synthesized. The structure of [(ppy)2Irppz]Cl was determined by single crystal X-ray diffraction. Their photophysical properties were also studied. This kind of complexes could coordinate with Cu2 +, the photoluminescence (PL) of the complex was quenched, and the color changed from orange-red to green. The forming M-Cu (M: complexes 1 and 2) ensemble could be further utilized as a colorimetric and emission "turn-on" bifunctional detection for CN-, especially for complex 1-Cu2 + showed a high sensitivity toward CN- with a limit of diction is 97 nM. Importantly, this kind of iridium(III) complexes shows a unique recognition of cyanide ions over other anions which makes it an eligible sensing probe for cyanide ions.

  19. Perfluoroalkyl Cobalt(III) Fluoride and Bis(perfluoroalkyl) Complexes: Catalytic Fluorination and Selective Difluorocarbene Formation.

    PubMed

    Leclerc, Matthew C; Bayne, Julia M; Lee, Graham M; Gorelsky, Serge I; Vasiliu, Monica; Korobkov, Ilia; Harrison, Daniel J; Dixon, David A; Baker, R Tom

    2015-12-30

    Four perfluoroalkyl cobalt(III) fluoride complexes have been synthesized and characterized by elemental analysis, multinuclear NMR spectroscopy, X-ray crystallography, and powder X-ray diffraction. The remarkable cobalt fluoride (19)F NMR chemical shifts (-716 to -759 ppm) were studied computationally, and the contributing paramagnetic and diamagnetic factors were extracted. Additionally, the complexes were shown to be active in the catalytic fluorination of p-toluoyl chloride. Furthermore, two examples of cobalt(III) bis(perfluoroalkyl)complexes were synthesized and their reactivity studied. Interestingly, abstraction of a fluoride ion from these complexes led to selective formation of cobalt difluorocarbene complexes derived from the trifluoromethyl ligand. These electrophilic difluorocarbenes were shown to undergo insertion into the remaining perfluoroalkyl fragment, demonstrating the elongation of a perfluoroalkyl chain arising from a difluorocarbene insertion on a cobalt metal center. The reactions of both the fluoride and bis(perfluoroalkyl) complexes provide insight into the potential catalytic applications of these model systems to form small fluorinated molecules as well as fluoropolymers.

  20. Green Phosphorescence and Electroluminescence of Sulfur Pentafluoride-Functionalized Cationic Iridium(III) Complexes.

    PubMed

    Shavaleev, Nail M; Xie, Guohua; Varghese, Shinto; Cordes, David B; Slawin, Alexandra M Z; Momblona, Cristina; Ortí, Enrique; Bolink, Henk J; Samuel, Ifor D W; Zysman-Colman, Eli

    2015-06-15

    We report on four cationic iridium(III) complexes [Ir(C^N)2(dtBubpy)](PF6) that have sulfur pentafluoride-modified 1-phenylpyrazole and 2-phenylpyridine cyclometalating (C^N) ligands (dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridyl). Three of the complexes were characterized by single-crystal X-ray structure analysis. In cyclic voltammetry, the complexes undergo reversible oxidation of iridium(III) and irreversible reduction of the SF5 group. They emit bright green phosphorescence in acetonitrile solution and in thin films at room temperature, with emission maxima in the range of 482-519 nm and photoluminescence quantum yields of up to 79%. The electron-withdrawing sulfur pentafluoride group on the cyclometalating ligands increases the oxidation potential and the redox gap and blue-shifts the phosphorescence of the iridium complexes more so than the commonly employed fluoro and trifluoromethyl groups. The irreversible reduction of the SF5 group may be a problem in organic electronics; for example, the complexes do not exhibit electroluminescence in light-emitting electrochemical cells (LEECs). Nevertheless, the complexes exhibit green to yellow-green electroluminescence in doped multilayer organic light-emitting diodes (OLEDs) with emission maxima ranging from 501 nm to 520 nm and with an external quantum efficiency (EQE) of up to 1.7% in solution-processed devices.

  1. Hydrolysis and cytotoxic properties of osmium(II)/(III)-DMSO-azole complexes. Short communication.

    PubMed

    Egger, Alexander; Cebrián-Losantos, Berta; Stepanenko, Iryna N; Krokhin, Artem A; Eichinger, Rene; Jakupec, Michael A; Arion, Vladimir B; Keppler, Bernhard K

    2008-08-01

    The antiproliferative properties of the osmium(II) complexes cis,fac-[Os(II)Cl(2)(DMSO)(3)(L)] and trans,cis,cis-[Os(II)Cl(2)(DMSO)(2)(L)(2)] (L = 1H-pyrazole, 1H-imidazole) were studied in three human cancer cell lines, namely 41M (ovary), SK-BR-3 (breast), and SW480 (colon). Their activities were compared with those of osmium(III) and ruthenium(III) NAMI-A type complexes on HT-29 (colon) and SK-BR-3 cancer cell lines. While IC(50) values of all the Os(II) complexes were found to be >1000 microM in all cell lines, Os and Ru-NAMI-A type complexes showed remarkable antiproliferative activity. The marginal in vitro cytotoxicity of the Os(II) compounds is presumably attributed to their resistance to hydrolysis. However, the Os-NAMI-A complexes, which are also kinetically stable in aqueous solution, showed reasonable antiproliferative activity in vitro when compared with the analogous Ru compounds and with the Os(II)-DMSO-azole species, indicating that hydrolysis might be not a prerequisite for the antitumor activity of Os-NAMI-A type complexes.

  2. Complete Mitochondrial Complex I Deficiency Induces an Up-Regulation of Respiratory Fluxes That Is Abolished by Traces of Functional Complex I1[OPEN

    PubMed Central

    Feher, Kristen; Fernie, Alisdair R.

    2015-01-01

    Complex I (NADH:ubiquinone oxidoreductase) is central to cellular NAD+ recycling and accounts for approximately 40% of mitochondrial ATP production. To understand how complex I function impacts respiration and plant development, we isolated Arabidopsis (Arabidopsis thaliana) lines that lack complex I activity due to the absence of the catalytic subunit NDUFV1 (for NADH:ubiquinone oxidoreductase flavoprotein1) and compared these plants with ndufs4 (for NADH:ubiquinone oxidoreductase Fe-S protein4) mutants possessing trace amounts of complex I. Unlike ndufs4 plants, ndufv1 lines were largely unable to establish seedlings in the absence of externally supplied sucrose. Measurements of mitochondrial respiration and ATP synthesis revealed that compared with ndufv1, the complex I amounts retained by ndufs4 did not increase mitochondrial respiration and oxidative phosphorylation capacities. No major differences were seen in the mitochondrial proteomes, cellular metabolomes, or transcriptomes between ndufv1 and ndufs4. The analysis of fluxes through the respiratory pathway revealed that in ndufv1, fluxes through glycolysis and the tricarboxylic acid cycle were dramatically increased compared with ndufs4, which showed near wild-type-like fluxes. This indicates that the strong growth defects seen for plants lacking complex I originate from a switch in the metabolic mode of mitochondria and an up-regulation of respiratory fluxes. Partial reversion of these phenotypes when traces of active complex I are present suggests that complex I is essential for plant development and likely acts as a negative regulator of respiratory fluxes. PMID:26134164

  3. Decaffeinated green tea extract rich in epigallocatechin-3-gallate prevents fatty liver disease by increased activities of mitochondrial respiratory chain complexes in diet-induced obesity mice.

    PubMed

    Santamarina, Aline B; Carvalho-Silva, Milena; Gomes, Lara M; Okuda, Marcos H; Santana, Aline A; Streck, Emilio L; Seelaender, Marilia; do Nascimento, Claudia M Oller; Ribeiro, Eliane B; Lira, Fábio S; Oyama, Lila Missae

    2015-11-01

    Nonalcoholic fatty liver disease has been considered the hepatic manifestation of obesity. It is unclear whether supplementation with green tea extract rich in epigallocatechin-3-gallate (EGCG) influences the activity of mitochondrial respiratory chain complexes and insulin resistance in the liver. EGCG regulated hepatic mitochondrial respiratory chain complexes and was capable of improving lipid metabolism, attenuating insulin resistance in obese mice. Mice were divided into four groups: control diet+water (CW) or EGCG (CE) and hyperlipidic diet+water (HFW) or EGCG (HFE). All animals received water and diets ad libitum for 16 weeks. Placebo groups received water (0.1 ml/day) and EGCG groups (0.1 ml EGCG and 50 mg/kg/day) by gavage. Cytokines concentrations were obtained by ELISA, protein expression through Western blotting and mitochondrial complex enzymatic activity by colorimetric assay of substrate degradation. HFW increased body weight gain, adiposity index, retroperitoneal and mesenteric adipose tissue relative weight, serum glucose, insulin and Homeostasis Model Assessment of Basal Insulin Resistance (HOMA-IR); glucose intolerance was observed in oral glucose tolerance test (OGTT) as well as ectopic fat liver deposition. HFE group decreased body weight gain, retroperitoneal and mesenteric adipose tissue relative weight, HOMA-IR, insulin levels and liver fat accumulation; increased complexes II-III and IV and malate dehydrogenase activities and improvement in glucose uptake in OGTT and insulin sensitivity by increased protein expression of total AKT, IRα and IRS1. We did not find alterations in inflammatory parameters analyzed. EGCG was able to prevent obesity stimulating the mitochondrial complex chain, increasing energy expenditure, particularly from the oxidation of lipid substrates, thereby contributing to the prevention of hepatic steatosis and improved insulin sensitivity. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Disruption of a nuclear gene encoding a mitochondrial gamma carbonic anhydrase reduces complex I and supercomplex I + III2 levels and alters mitochondrial physiology in Arabidopsis.

    PubMed

    Perales, Mariano; Eubel, Holger; Heinemeyer, Jesco; Colaneri, Alejandro; Zabaleta, Eduardo; Braun, Hans-Peter

    2005-07-08

    Mitochondrial NADH dehydrogenase (complex I) of plants includes quite a number of plant-specific subunits, some of which exhibit sequence similarity to bacterial gamma-carbonic anhydrases. A homozygous Arabidopsis knockout mutant carrying a T-DNA insertion in a gene encoding one of these subunits (At1g47260) was generated to investigate its physiological role. Isolation of mitochondria and separation of mitochondrial protein complexes by Blue-native polyacrylamide gel electrophoresis or sucrose gradient ultracentrifugation revealed drastically reduced complex I levels. Furthermore, the mitochondrial I + III2 supercomplex was very much reduced in mutant plants. Remaining complex I had normal molecular mass, suggesting substitution of the At1g47260 protein by one or several of the structurally related subunits of this respiratory protein complex. Immune-blotting experiments using polyclonal antibodies directed against the At1g47260 protein indicated its presence within complex I, the I + III2 supercomplex and smaller protein complexes, which possibly represent subcomplexes of complex I. Changes within the mitochondrial proteome of mutant cells were systematically monitored by fluorescence difference gel electrophoresis using 2D Blue-native/SDS and 2D isoelectric focussing/SDS polyacrylamide gel electrophoresis. Complex I subunits are largely absent within the mitochondrial proteome. Further mitochondrial proteins are reduced in mutant plants, like mitochondrial ferredoxin, others are increased, like formate dehydrogenase. Development of mutant plants was normal under standard growth conditions. However, a suspension cell culture generated from mutant plants exhibited clearly reduced growth rates and respiration. In summary, At1g47260 is important for complex I assembly in plant mitochondria and respiration. A role of At1g47260 in mitochondrial one-carbon metabolism is supported by micro-array analyses.

  5. Electron tunneling rates in respiratory complex I are tuned for efficient energy conversion.

    PubMed

    de Vries, Simon; Dörner, Katerina; Strampraad, Marc J F; Friedrich, Thorsten

    2015-02-23

    Respiratory complex I converts the free energy of ubiquinone reduction by NADH into a proton motive force, a redox reaction catalyzed by flavin mononucleotide(FMN) and a chain of seven iron-sulfur centers. Electron transfer rates between the centers were determined by ultrafast freeze-quenching and analysis by EPR and UV/Vis spectroscopy. The complex rapidly oxidizes three NADH molecules. The electron-tunneling rate between the most distant centers in the middle of the chain depends on the redox state of center N2 at the end of the chain, and is sixfold slower when N2 is reduced. The conformational changes that accompany reduction of N2 decrease the electronic coupling of the longest electron-tunneling step. The chain of iron-sulfur centers is not just a simple electron-conducting wire; it regulates the electron-tunneling rate synchronizing it with conformation-mediated proton pumping, enabling efficient energy conversion. Synchronization of rates is a principle means of enhancing the specificity of enzymatic reactions. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

  6. Redox-induced activation of the proton pump in the respiratory complex I.

    PubMed

    Sharma, Vivek; Belevich, Galina; Gamiz-Hernandez, Ana P; Róg, Tomasz; Vattulainen, Ilpo; Verkhovskaya, Marina L; Wikström, Mårten; Hummer, Gerhard; Kaila, Ville R I

    2015-09-15

    Complex I functions as a redox-linked proton pump in the respiratory chains of mitochondria and bacteria, driven by the reduction of quinone (Q) by NADH. Remarkably, the distance between the Q reduction site and the most distant proton channels extends nearly 200 Å. To elucidate the molecular origin of this long-range coupling, we apply a combination of large-scale molecular simulations and a site-directed mutagenesis experiment of a key residue. In hybrid quantum mechanics/molecular mechanics simulations, we observe that reduction of Q is coupled to its local protonation by the His-38/Asp-139 ion pair and Tyr-87 of subunit Nqo4. Atomistic classical molecular dynamics simulations further suggest that formation of quinol (QH2) triggers rapid dissociation of the anionic Asp-139 toward the membrane domain that couples to conformational changes in a network of conserved charged residues. Site-directed mutagenesis data confirm the importance of Asp-139; upon mutation to asparagine the Q reductase activity is inhibited by 75%. The current results, together with earlier biochemical data, suggest that the proton pumping in complex I is activated by a unique combination of electrostatic and conformational transitions.

  7. Respiratory complex I deficiency induces drought tolerance by impacting leaf stomatal and hydraulic conductances.

    PubMed

    Djebbar, Reda; Rzigui, Touhami; Pétriacq, Pierre; Mauve, Caroline; Priault, Pierrick; Fresneau, Chantal; De Paepe, Marianne; Florez-Sarasa, Igor; Benhassaine-Kesri, Ghouziel; Streb, Peter; Gakière, Bertrand; Cornic, Gabriel; De Paepe, Rosine

    2012-03-01

    To investigate the role of plant mitochondria in drought tolerance, the response to water deprivation was compared between Nicotiana sylvestris wild type (WT) plants and the CMSII respiratory complex I mutant, which has low-efficient respiration and photosynthesis, high levels of amino acids and pyridine nucleotides, and increased antioxidant capacity. We show that the delayed decrease in relative water content after water withholding in CMSII, as compared to WT leaves, is due to a lower stomatal conductance. The stomatal index and the abscisic acid (ABA) content were unaffected in well-watered mutant leaves, but the ABA/stomatal conductance relation was altered during drought, indicating that specific factors interact with ABA signalling. Leaf hydraulic conductance was lower in mutant leaves when compared to WT leaves and the role of oxidative aquaporin gating in attaining a maximum stomatal conductance is discussed. In addition, differences in leaf metabolic status between the mutant and the WT might contribute to the low stomatal conductance, as reported for TCA cycle-deficient plants. After withholding watering, TCA cycle derived organic acids declined more in CMSII leaves than in the WT, and ATP content decreased only in the CMSII. Moreover, in contrast to the WT, total free amino acid levels declined whilst soluble protein content increased in CMSII leaves, suggesting an accelerated amino acid remobilisation. We propose that oxidative and metabolic disturbances resulting from remodelled respiration in the absence of Complex I activity could be involved in bringing about the lower stomatal and hydraulic conductances.

  8. Redox-induced activation of the proton pump in the respiratory complex I

    PubMed Central

    Sharma, Vivek; Belevich, Galina; Gamiz-Hernandez, Ana P.; Róg, Tomasz; Vattulainen, Ilpo; Verkhovskaya, Marina L.; Wikström, Mårten; Hummer, Gerhard; Kaila, Ville R. I.

    2015-01-01

    Complex I functions as a redox-linked proton pump in the respiratory chains of mitochondria and bacteria, driven by the reduction of quinone (Q) by NADH. Remarkably, the distance between the Q reduction site and the most distant proton channels extends nearly 200 Å. To elucidate the molecular origin of this long-range coupling, we apply a combination of large-scale molecular simulations and a site-directed mutagenesis experiment of a key residue. In hybrid quantum mechanics/molecular mechanics simulations, we observe that reduction of Q is coupled to its local protonation by the His-38/Asp-139 ion pair and Tyr-87 of subunit Nqo4. Atomistic classical molecular dynamics simulations further suggest that formation of quinol (QH2) triggers rapid dissociation of the anionic Asp-139 toward the membrane domain that couples to conformational changes in a network of conserved charged residues. Site-directed mutagenesis data confirm the importance of Asp-139; upon mutation to asparagine the Q reductase activity is inhibited by 75%. The current results, together with earlier biochemical data, suggest that the proton pumping in complex I is activated by a unique combination of electrostatic and conformational transitions. PMID:26330610

  9. Brownie, a Gene Involved in Building Complex Respiratory Devices in Insect Eggshells

    PubMed Central

    Irles, Paula; Bellés, Xavier; Piulachs, M. Dolors

    2009-01-01

    Background Insect eggshells must combine protection for the yolk and embryo with provisions for respiration and for the entry of sperm, which are ensured by aeropyles and micropyles, respectively. Insects which oviposit the eggs in an egg-case have a double problem of respiration as gas exchange then involves two barriers. An example of this situation is found in the cockroach Blattella germanica, where the aeropyle and the micropyle are combined in a complex structure called the sponge-like body. The sponge-like body has been well described morphologically, but nothing is known about how it is built up. Methodology/Principal Findings In a library designed to find genes expressed during late chorion formation in B. germanica, we isolated the novel sequence Bg30009 (now called Brownie), which was outstanding due to its high copy number. In the present work, we show that Brownie is expressed in the follicle cells localized in the anterior pole of the oocyte in late choriogenesis. RNA interference (RNAi) of Brownie impaired correct formation of the sponge-like body and, as a result, the egg-case was also ill-formed and the eggs were not viable. Conclusions/Significance Results indicate that the novel gene Brownie plays a pivotal role in building up the sponge-like body. Brownie is the first reported gene involved in the construction of complex eggshell respiratory structures. PMID:20020062

  10. X-ray diffraction, FTIR, UV-VIS and SEM studies on chromium (III) complexes

    SciTech Connect

    Mishra, Ashutosh; Dwivedi, Jagrati Shukla, Kritika

    2015-06-24

    Five Chromium (III) complexes have been prepared using Schiff base ligands which derived from benzoin and five different amino acids (H{sub 2}N-R). Samples were characterized by XRD, FTIR, UV-VIS and SEM method. X-Ray diffraction pattern analyzed that all chromium (III) complexes have hexagonal structure and crystalline, in nature, using Bruker D8 Advance instrument. Using VERTAX 70, FTIR spectroscopy reveals that Samples have (C=N), (C-O), (M-N) and (M-O) bonds in the range of 4000-400cm{sup −1}. UV-VIS spectroscopy give information that samples absorb the visible light which is in the range of 380-780nm. For this, Lambda 960 spectrometer used. SEM is designed for studying of the solid objects, using JEOL JSM 5600 instrument.

  11. Synthesis, characterization and antibacterial study of cyclometalated rhodium(III) complex containing dithiocarbamate

    NASA Astrophysics Data System (ADS)

    Mansouri, Ghobad; Heidarizadi, Fateme; Naghipour, Ali; Notash, Behrouz

    2016-10-01

    The novel cyclometalated Rh(III) complex, [Rh(phpy)2(SˆS)], Where phpy is 2-phenylpyridine and (SˆS) is diethyldithiocarbamate, has been prepared and characterized by elemental analysis, IR, 13C and 1H NMR, electronic absorption and Fluorescence spectroscopies, cyclic voltammetry, and X-ray crystallography. The crystal structure of [Rh(phpy)2(SˆS)] shows that the coordination geometry around the Rh(III) is a distorted octahedron, with bite angles of 71.19-81.04° for all three bidentate ligands. Electrochemical analysis by cyclic voltammetry reveals irreversible redox behavior of the rhodium centre. Antibacterial activity of the complex has also been studied by agar disc diffusion method against three Gram-negative bacteria (Pseudomonas aeroginosa, Salmonella typhi and Escherichia coli) and two Gram-positive bacteria (Staphylococcus aureus and Corynebacterium renale).

  12. Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties

    NASA Astrophysics Data System (ADS)

    Selvi, Canan; Nartop, Dilek

    2012-09-01

    New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

  13. Heptachlor induced mitochondria-mediated cell death via impairing electron transport chain complex III

    SciTech Connect

    Hong, Seokheon; Kim, Joo Yeon; Hwang, Joohyun; Shin, Ki Soon; Kang, Shin Jung

    2013-08-09

    Highlights: •Heptachlor inhibited mitochondrial electron transport chain complex III activity. •Heptachlor promoted generation of reactive oxygen species. •Heptachlor induced Bax activation. •Heptachlor induced mitochondria-mediated and caspase-dependent apoptosis. -- Abstract: Environmental toxins like pesticides have been implicated in the pathogenesis of Parkinson’s disease (PD). Epidemiological studies suggested that exposures to organochlorine pesticides have an association with an increased PD risk. In the present study, we examined the mechanism of toxicity induced by an organochlorine pesticide heptachlor. In a human dopaminergic neuroblastoma SH-SY5Y cells, heptachlor induced both morphological and functional damages in mitochondria. Interestingly, the compound inhibited mitochondrial electron transport chain complex III activity. Rapid generation of reactive oxygen species and the activation of Bax were then detected. Subsequently, mitochondria-mediated, caspase-dependent apoptosis followed. Our results raise a possibility that an organochlorine pesticide heptachlor can act as a neurotoxicant associated with PD.

  14. Interaction of curcumin with Al(III) and its complex structures based on experiments and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Jiang, Teng; Wang, Long; Zhang, Sui; Sun, Ping-Chuan; Ding, Chuan-Fan; Chu, Yan-Qiu; Zhou, Ping

    2011-10-01

    Curcumin has been recognized as a potential natural drug to treat the Alzheimer's disease (AD) by chelating baleful metal ions, scavenging radicals and preventing the amyloid β (Aβ) peptides from the aggregation. In this paper, Al(III)-curcumin complexes with Al(III) were synthesized and characterized by liquid-state 1H, 13C and 27Al nuclear magnetic resonance (NMR), mass spectroscopy (MS), ultraviolet spectroscopy (UV) and generalized 2D UV-UV correlation spectroscopy. In addition, the density functional theory (DFT)-based UV and chemical shift calculations were also performed to view insight into the structures and properties of curcumin and its complexes. It was revealed that curcumin could interact strongly with Al(III) ion, and form three types of complexes under different molar ratios of [Al(III)]/[curcumin], which would restrain the interaction of Al(III) with the Aβ peptide, reducing the toxicity effect of Al(III) on the peptide.

  15. Evaluating the metagenome of two sampling locations in the nasal cavity of cattle with bovine respiratory disease complex

    USDA-ARS?s Scientific Manuscript database

    Bovine respiratory disease complex (BRDC) is a multi-factor disease, and disease incidence may be associated with an animal’s commensal microbiota (metagenome). Evaluation of the animal’s resident microbiota in the nasal cavity may help us to understand the impact of the metagenome on incidence of ...

  16. Closed genomes and phenotypes of seven Histophilus somni isolates from beef calves with bovine respiratory disease complex

    USDA-ARS?s Scientific Manuscript database

    Background: Histophilus somni is a fastidious gram-negative opportunistic pathogenic Pasteurellacea that affects multiple organ systems and is one of three principle bacterial species contributing to bovine respiratory disease complex (BRDC) in North American feed yard cattle. BRDC outbreaks accoun...

  17. Experimental and Computational Evidence for the Mechanism of Intradiol Catechol Dioxygenation by Non-Heme Iron(III) Complexes

    PubMed Central

    Jastrzebski, Robin; Quesne, Matthew G; Weckhuysen, Bert M; de Visser, Sam P; Bruijnincx, Pieter C A

    2014-01-01

    Catechol intradiol dioxygenation is a unique reaction catalyzed by iron-dependent enzymes and non-heme iron(III) complexes. The mechanism by which these systems activate dioxygen in this important metabolic process remains controversial. Using a combination of kinetic measurements and computational modelling of multiple iron(III) catecholato complexes, we have elucidated the catechol cleavage mechanism and show that oxygen binds the iron center by partial dissociation of the substrate from the iron complex. The iron(III) superoxide complex that is formed subsequently attacks the carbon atom of the substrate by a rate-determining C=O bond formation step. PMID:25322920

  18. Photocatalytic C-C Bond Cleavage and Amination of Cycloalkanols by Cerium(III) Chloride Complex.

    PubMed

    Guo, Jing-Jing; Hu, Anhua; Chen, Yilin; Sun, Jianfeng; Tang, Haoming; Zuo, Zhiwei

    2016-12-05

    A general strategy for the cleavage and amination of C-C bonds of cycloalkanols has been achieved through visible-light-induced photoredox catalysis utilizing a cerium(III) chloride complex. This operationally simple methodology has been successfully applied to a wide array of unstrained cyclic alcohols, and represents the first example of catalytic C-C bond cleavage and functionalization of unstrained secondary cycloalkanols.

  19. Synthesis and structures of a pincer-type rhodium(iii) complex: reactivity toward biomolecules.

    PubMed

    Milutinović, Milan M; Bogojeski, Jovana V; Klisurić, Olivera; Scheurer, Andreas; Elmroth, Sofi K C; Bugarčić, Živadin D

    2016-10-04

    A novel rhodium(iii) complex [Rh(III)(H2L(tBu))Cl3] (1) (H2L(tBu) = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine) containing a pincer type, tridentate nitrogen-donor chelate system was synthesized. Single crystal X-ray structure analysis revealed that 1 crystallizes in the orthorhombic space group Pbcn with a = 20.7982(6), b = 10.8952(4), c = 10.9832(4) Å, V = 2488.80(15) Å(3), and eight molecules in the unit cell. The rhodium center in the complex [Rh(III)(H2L(tBu))Cl3] (1) is coordinated in a slightly distorted octahedral geometry by the tridentate N,N,N-donor and three chloro ligands, adopting a mer arrangement with an essentially planar ligand skeleton. Due to the tridentate coordination of the N,N,N-donor, the central nitrogen atom N1 is located closer to the Rh(III) center. The reactivity of the synthesized complex toward small biomolecules (l-methionine (l-Met), guanosine-5'-monophosphate (5'-GMP), l-histidine (l-His) and glutathione (GSH)) and to a series of duplex DNAs and RNA was investigated. The order of reactivity of the studied small biomolecules is: 5'-GMP > GSH > l-Met > l-His. Duplex RNA reacts faster with the [Rh(III)(H2L(tBu))Cl3] complex than duplex DNA, while shorter duplex DNA (15mer GG) reacts faster compared with 22mer GG duplex DNA. In addition, a higher reactivity is achieved with a DNA duplex with a centrally located GG-sequence than with a 22GTG duplex DNA, in which the GG-sequence is separated by a T base. Furthermore, the interaction of this metal complex 1 with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) was examined by absorption (UV-Vis) and emission spectral studies (EthBr displacement studies). Overall, the studied complex exhibited good DNA and BSA interaction ability.

  20. Theoretical and spectroscopic studies of pyridyl substituted bis-coumarins and their new neodymium (III) complexes

    NASA Astrophysics Data System (ADS)

    Kostova, Irena; Trendafilova, Natasha; Mihaylov, Tzvetan

    2005-07-01

    Ab initio, DFT and spectroscopic studies of 3,3'-( o-pyridinomethylene)di-[4-hydroxycoumarin], 3,3'-( m-pyridinomethylene)di-[4-hydroxycoumarin] and 3,3'-( p-pyridinomethylene)di-[4-hydroxycoumarin] were performed. The molecular and electronic structures of the compounds were investigated using accurate HF and B3LYP/6-31G(d) calculations. Molecular quantities as vertical ionization potential, electron affinity, electronegativity, hardness and electrophilicity indices of the neutral species were calculated and discussed. Molecular electrostatic potential was considered as an additional molecular characteristic for predicting the most probable sites for electrophilic attack. The molecular structure and quantities of the dianionic species, which are active in solution, were calculated and discussed. The theoretical results suggested that both carbonyl and both hydroxyl oxygen atoms are preferred binding sites for electrophilic attack, in particular for a metal coordination. Further, the coordination abilities of the compounds were studied in complexation reactions with Nd(III). Complexes of Nd(III) with o-, m- and p-3,3'-(pyridinomethylene)di-[4-hydroxycoumarin] were synthesized and characterized by different physicochemical methods: elemental analysis, IR, 1H NMR spectroscopies and mass spectral data. The experimental data confirmed the theoretical predictions that the ligands in Nd(III) complexes are tetradentate and bound the metal ion through both carbonyl and both deprotonated hydroxyl oxygen atoms.

  1. Kinetic studies of nitrate removal from aqueous solution using granular chitosan-Fe(III) complex.

    PubMed

    Hu, Qili; Chen, Nan; Feng, Chuanping; Zhang, Jing; Hu, Weiwu; Lv, Long

    2016-01-01

    In the present study, a granular chitosan-Fe(III) complex was prepared as a feasible adsorbent for the removal of nitrate from an aqueous solution. There was no significant change in terms of nitrate removal efficiency over a wide pH range of 3-11. Nitrate adsorption on the chitosan-Fe(III) complex followed the Langmuir-Freundlich isotherm model. In order to more accurately reflect adsorption and desorption behaviors at the solid/solution interface, kinetic model I and kinetic model II were proposed to simulate the interfacial process in a batch system. Nitrate adsorption on the chitosan-Fe(III) complex followed the pseudo-first-order kinetic model and kinetic model I. The proposed half-time could provide useful information for optimizing process design. Adsorption and desorption rate constants obtained from kinetic model I and kinetic model II were beneficial to understanding the interfacial process and the extent of adsorption reaction. Kinetic model I and kinetic model II implied that nitrate uptake exponentially approaches a limiting value.

  2. Crystal structures of two ytterbium(III) complexes comprising alkynylamidinate ligands

    PubMed Central

    Wang, Sida; Sroor, Farid M.; Liebing, Phil; Lorenz, Volker; Hilfert, Liane; Edelmann, Frank T.

    2016-01-01

    Two ytterbium(III) complexes comprising alkynylamidinate ligands, namely bis­(η5-cyclo­penta­dien­yl)(3-cyclo­propyl-N,N′-diiso­propyl­propynamidinato-κ2 N,N′)ytterbium(III), [Yb(C5H5)2(C12H19N2)] or Cp2Yb[(iPr2N)2C—C≡C—c-C3H5] (1) and tris­(3-phenyl-N,N′-di­cyclo­hexyl­propynamidinato-κ2 N,N′)ytterbium(III), [Yb(C21H27N2)3] or Yb[(CyN)2C—C≡C—Ph]3 (Cy = cyclo­hex­yl) (2) have been synthesized and structurally characterized. Both complexes are monomers; for complex 2, the contribution to the scattering from highly disordered toluene solvent molecules in these voids was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON. The stated crystal data for Mr, μ etc. do not take these into account. PMID:27920904

  3. Structural and catalytic properties of some azo-rhodanine Ruthenium(III) complexes

    NASA Astrophysics Data System (ADS)

    Shoair, A. F.; El-Bindary, A. A.; Abd El-Kader, M. K.

    2017-09-01

    Novel azo-rhodanine ruthenium(III) complexes of the type trans-[Ru(Ln)2(AsPh3)2]Cl (Ln = monobasic bidentate anions of 5-(4‧-methoxyphenylazo)-3-phenylamino-2-thioxothiazolidin-4-one (HL1), 5-(phenylazo)-3-phenylamino-2-thioxothiazolidin-4-one (HL2) and 5-(4‧-chlorophenylazo)-3-phenylamino-2-thioxothiazolidin-4-one (HL3); AsPh3 = triphenylarsine) have been synthesized and characterized by elemental analysis, spectroscopic (IR, 1H NMR and UV-VIS), magnetic, X-ray diffraction, mass spectra and thermal analysis techniques. These techniques confirm the formation of octahedral ruthenium(III) complexes. The Ru(III) complexes were tested as a catalysts for the oxidation of benzyl alcohol to benzaldehyde with N-methylmorpholine-N-oxide as a co-oxidant. The effect of time, temperature, and solvent were also studied and the mechanism of this catalytic oxidation reaction is suggested. Molecular docking was used to predict the binding between azo rhodanine derivatives (HLn) with the receptor of 3qum- immune system receptor of human prostate specific antigen (PSA) in a Fab sandwich with a high affinity and a PCa selective antibody.

  4. Crystal structures of two ytterbium(III) complexes comprising alkynylamidinate ligands.

    PubMed

    Wang, Sida; Sroor, Farid M; Liebing, Phil; Lorenz, Volker; Hilfert, Liane; Edelmann, Frank T

    2016-09-01

    Two ytterbium(III) complexes comprising alkynylamidinate ligands, namely bis-(η(5)-cyclo-penta-dien-yl)(3-cyclo-propyl-N,N'-diiso-propyl-propynamidinato-κ(2)N,N')ytterbium(III), [Yb(C5H5)2(C12H19N2)] or Cp2Yb[( (i) Pr2N)2C-C≡C-c-C3H5] (1) and tris-(3-phenyl-N,N'-di-cyclo-hexyl-propynamidinato-κ(2)N,N')ytterbium(III), [Yb(C21H27N2)3] or Yb[(CyN)2C-C≡C-Ph]3 (Cy = cyclo-hex-yl) (2) have been synthesized and structurally characterized. Both complexes are monomers; for complex 2, the contribution to the scattering from highly disordered toluene solvent molecules in these voids was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18] in PLATON. The stated crystal data for Mr, μ etc. do not take these into account.

  5. Me-3,2-HOPO Complexes of Near Infra-Red (NIR) Emitting Lanthanides: Efficient Sensitization of Yb(III) and Nd(III) in Aqueous Solution

    SciTech Connect

    Moore, Evan G.; Xu, Jide; Dodani, Sheel; Jocher, Christoph; D'Aleo, Anthony; Seitz, Michael; Raymond, Kenneth

    2009-11-10

    The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution ({Phi}{sub tot}{sup Yb} {approx} 0.09-0.22%). Furthermore, the complexes demonstrate very high stability (pYb {approx} 18.8-21.9) in aqueous solution, making them good candidates for further development as probes for NIR imaging. Analysis of the low temperature (77 K) photophysical measurements for a model Gd(III) complex were used to gain an insight into the electronic structure, and were found to agree well with corresponding TD-DFT calculations at the B3LYP/6-311G{sup ++}(d,p) level of theory for a simplified model monovalent sodium complex.

  6. Me-3,2-HOPO Complexes of Near Infra-Red (NIR) Emitting Lanthanides: Efficient Sensitization of Yb(III) and Nd(III) in Aqueous Solution

    PubMed Central

    Moore, Evan G.; Xu, Jide; Dodani, Sheel C.; Jocher, Christoph J.; D'Aléo, Anthony; Seitz, Michael; Raymond, Kenneth N.

    2011-01-01

    The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution (ΦtotYb~0.09−0.22%). Furthermore, the complexes demonstrate very high stability (pYb ~ 18.8 – 21.9) in aqueous solution, making them good candidates for further development as probes for NIR imaging. Analysis of the low temperature (77 K) photophysical measurements for a model Gd(III) complex were used to gain an insight into the electronic structure, and were found to agree well with corresponding TD-DFT calculations at the B3LYP/6-311G++(d,p) level of theory for a simplified model monovalent sodium complex. PMID:20364838

  7. Unexpected formation of a novel pyridinium-containing catecholate ligand and its manganese(III) complex.

    PubMed

    Sheriff, Tippu S; Watkinson, Michael; Motevalli, Majid; Lesin, Jocelyne F

    2010-01-07

    Nucleophilic aromatic substitution of tetrachloro-o-benzoquinone by pyridine and reduction of the o-quinone to the catechol by hydroxylamine forms 1,2-dihydroxy-3,5,6-trichlorobenzene-4-pyridinium chloride. This compound reacts with manganese(II) acetate in air to form chlorobis(3,5,6-trichlorobenzene 4-pyridinium catecholate)manganese(III), which represents the first complex of this ligand class to be structurally characterized by X-ray diffraction; this complex is active in the catalytic reduction of dioxygen to hydrogen peroxide under ambient conditions and turnover frequencies (TOFs) >10,000 h(-1) can be obtained.

  8. A colorimetric chemosensor for Cu2+ ion detection based on an iridium(III) complex

    NASA Astrophysics Data System (ADS)

    Wang, Modi; Leung, Ka-Ho; Lin, Sheng; Chan, Daniel Shiu-Hin; Kwong, Daniel W. J.; Leung, Chung-Hang; Ma, Dik-Lung

    2014-10-01

    We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1-3 bearing a rhodamine-linked NˆN ligand for the detection of Cu2+ ions. Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu2+ ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8. Furthermore, the potential application of this system for the monitoring of Cu2+ ions in tap water or natural river water samples was demonstrated.

  9. A colorimetric chemosensor for Cu2+ ion detection based on an iridium(III) complex

    PubMed Central

    Wang, Modi; Leung, Ka-Ho; Lin, Sheng; Chan, Daniel Shiu-Hin; Kwong, Daniel W. J.; Leung, Chung-Hang; Ma, Dik-Lung

    2014-01-01

    We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1−3 bearing a rhodamine-linked NˆN ligand for the detection of Cu2+ ions. Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu2+ ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8. Furthermore, the potential application of this system for the monitoring of Cu2+ ions in tap water or natural river water samples was demonstrated. PMID:25348724

  10. Studies on the mechanism of action of antitumor bis(aminophenolate) ruthenium(III) complexes.

    PubMed

    Dömötör, Orsolya; de Almeida, Rodrigo F M; Côrte-Real, Leonor; Matos, Cristina P; Marques, Fernanda; Matos, António; Real, Carla; Kiss, Tamás; Enyedy, Éva Anna; Helena Garcia, M; Tomaz, Ana Isabel

    2017-03-01

    Two recently published Ru(III) complexes bearing (N2O2) tetradentate bis(aminophenolate) ligands, formulated as [Ru(III)(salan)(PPh3)Cl] (salan is the tetradentate ligand 6,6'-(1S,2S)-cyclohexane-1,2-diylbis(azanediyl)bis(methylene)bis(3-methoxyphenol) in complex 1, or 2,2'-(1S,2S)-cyclohexane-1,2-diylbis(azanediyl)bis(methylene)bis(4-methoxyphenol) in complex 2; PPh3 is triphenylphosphane) and found very active against ovarian and breast adenocarcinoma human cells were studied to outline their antitumor mode of action. The human cisplatin-sensitive ovarian adenocarcinoma line A2780 was used herein as the cell model. At a 24h challenge (similarly as found before for 72h) both complexes are active, their cytotoxicity being comparable to that of cisplatin in the same conditions. As a possible target in the cell for their action, the interaction of 1 and 2 with DNA was assessed through displacement of well-established DNA fluorescent probes (ethidium bromide, EB, and 4',6-diamidino-2-phenylindole, DAPI) through steady-state and time-resolved fluorescence spectroscopy. The whole emission spectra were analyzed globally for the binary DNA-probe and ternary DNA-probe-Ru(III) complex systems. Both Ru(III) complexes can displace EB and bind to DNA with similar and moderate strong affinity with conditional stability constants of logK'=(5.05±0.01) for 1 and logK'=(4.79±0.01) for 2. The analysis of time-domain fluorescence intensity decays confirmed both qualitatively and quantitatively the model used to describe the binding and competition processes. Cell studies indicated that apoptosis is the major mechanism of cell death for both complexes, with 2 (the more active complex) promoting that process more efficiently than 1. Transmission electron micrographs revealed clear alterations on intracellular organization consistent with the induction of programmed cell death processes.

  11. Construction of four low-dimensional NIR-luminescence-tunable Yb(III) complexes.

    PubMed

    Zheng, Zhi-Peng; Zhang, Xiu-Xia; Li, Teng; Yang, Jian; Wei, Lei-Ming; Zhang, Li-Guo; Lin, Xiao-Ming; Cai, Yue-Peng

    2014-10-07

    Four low-dimensional ytterbium(iii)-organic compounds through hydrothermal reactions of quinoline-2,3-dicarboxylic acid (2,3-H2qldc) and oxalic acid (H2ox) with Yb2O3, namely, [Yb(2,3-qldc)(ox)1/2(H2O)3·(H2O)4]n (1), [Yb(2,3-qldc)(ox)1/2(H2O)2·(H2O)2]n (2), [Yb(2,3-Hqldc)(ox)(H2O)2·(H2O)]n (3) and [Yb(2,3-Hqldc)(ox)(H2O)·(H2O)2]n (4), were first synthesized and characterized by elemental analysis (EA), infrared spectroscopy (IR), thermogravimetric analysis (TG), and single-crystal X-ray diffraction. When the reactant ratio of 2,3-H2qldc : H2ox : Yb2O3 is 2 : 1 : 1, 1-D chain-like complex 1 with three coordinated water molecules around the Yb(iii) ion was obtained in mixed solvents of H2O and CH3OH (v : v = 10 : 1) at 70 °C, and with the increase of temperature to 100 °C, the same reactants gave 2-D 6(3) topological layer-like complex 2 with two coordinated water molecules in the coordination sphere of the Yb(iii) ion. However, when the reactant ratio was changed to 1 : 1 : 1, two 2-D 6(3) topological layer-like complexes 3 (70 °C) and 4 (100 °C) were obtained at different temperatures, in which the coordination water molecules in 3 and 4 are two and one, respectively. Obviously, these results reveal that the reaction temperature and reactant ratios play critical roles in the structural direction of these low-dimensional compounds. Interestingly, with the gradual loss of coordination water molecules to the Yb(iii) ion, the near infrared (NIR) emission of four Yb(iii)-based compounds 1-4 can be gradually strengthened with increasing order of 1 < 3 < 2 < 4, indicating that these ytterbium(iii) complexes have tunable near infrared luminescence.

  12. Synthesis, luminescence properties of Eu(III) and Tb(III) complexes with a novel aromatic carboxylic acid and their interactions with bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Shen, Liqun; Yang, Zhengfa; Tang, Ruiren

    2012-12-01

    A novel aromatic carboxylic acid ligand (L) was synthesized and its corresponding Eu(III) and Tb(III) complexes, Na3EuLCl3·2H2O (EuL) and Na3TbLCl3·3H2O (TbL), were successfully prepared. L and its corresponding complexes were characterized by means of MS, elemental analysis, IR, 1H NMR and TG. The luminescence spectra of Eu(III) and Tb(III) complexes were investigated and the results showed that L was an efficient sensitizer for Eu(III) and Tb(III) luminescence. The interactions of L, EuL and TbL with bovine serum albumin (BSA) have been investigated through fluorescence spectroscopy under physiological conditions. The Stern-Volmer analysis indicated that the fluorescence quenching of BSA by L, EuL and TbL was resulted from static mechanism, and the binding constants (Ka) were 2.22 × 104, 1.33 × 105 and 4.27 × 105 at 300 K, respectively. The binding sites (n) and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated at different temperatures. According to the theoretical and experimental results, van der Waals interactions and hydrogen bonds were found to play major roles in the binding reaction. Furthermore, UV-Vis absorption spectroscopy and synchronous fluorescence spectra indicated that the conformation of BSA was changed. The results obtained in the work can help understand the action mode between L and its corresponding Eu(III) and Tb(III) complexes with BSA, and they are also expected to provide important information of designs of new inspired drugs based on Eu and Tb.

  13. Synthesis, spectral and electrochemical properties of Al(III) and Zn(II) complexes with flavonoids

    NASA Astrophysics Data System (ADS)

    Souza, Rubens F. V. de; De Giovani, Wagner F.

    2005-07-01

    The synthesis, electrochemical and spectral (UV-vis, 1H NMR, IR, fluorescence) properties as well as thermal behaviors of Al(III) and Zn(II) complexes with the flavonoids quercetin (H 2L 1), rutin (H 2L 2) and galangin (HL 3) are presented. The complexes may be formulated as [Al 2(L 1)(H 2O) 8]Cl 4, [Al 3(L 2) 2(H 2O) 12]Cl 5, [Al(L 3)(H 2O) 4]Cl 2, [Zn 2(L 1)(H 2O) 4]Cl 2, [Zn 3(L 2) 2(H 2O) 6]Cl 2 and [Zn(L 3)(H 2O) 2]Cl. The higher fluorescence intensities of the complexes related to the free flavonoids, are attributed to the coordination of the ligands to the small, highly charged Al(III) and Zn(II) ions. The coordination effectively increases the rigidity of the ligand structure and increases the fluorescence quantum yield by reducing the probability of non-radiative energy dissipation process. Antioxidant activities of the compounds were also investigated under an electrochemical point of view. The cyclic voltammetric data show a considerable decrease of the oxidation potentials of the complexes related to that of the free flavonoids. Thus, the flavonoid-metal complexes are more effective antioxidants than the free flavonoids.

  14. Synthesis and photophysical properties of europium(III)-β-diketonate complexes applied in LEDs.

    PubMed

    Shao, Guang; Yu, Huijuan; Zhang, Na; He, Yanjian; Feng, Kejun; Yang, Xin; Cao, Rihui; Gong, Menglian

    2014-01-14

    Six β-diketonate ligands were used to prepare the corresponding antenna europium(III) ternary complexes using 1,10-phenanthroline as an ancillary ligand. All the complexes exhibited high decomposition temperatures. Photophysical properties such as FT-IR spectra, UV-Vis absorption spectra, excitation and emission spectra, relative luminescent intensity ratios, luminescence decay curves and quantum yields based on the complexes were systematically studied and compared with each other. The energy-transfer mechanism was proposed as a ligand-sensitized luminescence process. Bright red light-emitting diodes (LEDs) were then fabricated by coating the complexes onto 395 nm-emitting InGaN chips. The light emission from the InGaN chips could be completely absorbed in the spectra of LEDs. The Commission International de I'Eclairage (CIE) chromaticity coordinates are close to the National Television Standard Committee (NTSC) standard value for the red color. All these findings indicate that these Eu(III) complexes are promising red phosphors for fabrication of near UV-based white LEDs.

  15. Electrostatics, hydration, and proton transfer dynamics in the membrane domain of respiratory complex I.

    PubMed

    Kaila, Ville R I; Wikström, Mårten; Hummer, Gerhard

    2014-05-13

    Complex I serves as the primary electron entry point into the mitochondrial and bacterial respiratory chains. It catalyzes the reduction of quinones by electron transfer from NADH, and couples this exergonic reaction to the translocation of protons against an electrochemical proton gradient. The membrane domain of the enzyme extends ∼180 Å from the site of quinone reduction to the most distant proton pathway. To elucidate possible mechanisms of the long-range proton-coupled electron transfer process, we perform large-scale atomistic molecular dynamics simulations of the membrane domain of complex I from Escherichia coli. We observe spontaneous hydration of a putative proton entry channel at the NuoN/K interface, which is sensitive to the protonation state of buried glutamic acid residues. In hybrid quantum mechanics/classical mechanics simulations, we find that the observed water wires support rapid proton transfer from the protein surface to the center of the membrane domain. To explore the functional relevance of the pseudosymmetric inverted-repeat structures of the antiporter-like subunits NuoL/M/N, we constructed a symmetry-related structure of a possible alternate-access state. In molecular dynamics simulations, we find the resulting structural changes to be metastable and reversible at the protein backbone level. However, the increased hydration induced by the conformational change persists, with water molecules establishing enhanced lateral connectivity and pathways for proton transfer between conserved ionizable residues along the center of the membrane domain. Overall, the observed water-gated transitions establish conduits for the unidirectional proton translocation processes, and provide a possible coupling mechanism for the energy transduction in complex I.

  16. Enhanced anti-cancer activities of a gold(III) pyrrolidinedithiocarbamato complex incorporated in a biodegradable metal-organic framework.

    PubMed

    Sun, Raymond Wai-Yin; Zhang, Ming; Li, Dan; Li, Mian; Wong, Alice Sze-Tsai

    2016-10-01

    An anti-cancer active gold(III) pyrrolidinedithiocarbamato complex [(PDTC)Au(III)Cl2] (1) has been synthesized and characterized by means of X-ray crystallography. Compared to the pyrrolidinedithiocarbamate ligand itself, this gold(III) complex displays an up to 33-fold higher anti-cancer potency towards a panel of cancer cell lines including the cisplatin-resistant ovarian carcinoma cell line (A2780cis). As demonstrated by a set of Transwell® assay-based cytotoxicity experiments, incorporating this gold(III) complex in a zinc-based biodegradable metal-organic framework (MOF) displays a significant enhancement in anti-cancer activity towards A2780cis than the gold(III) complex alone. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Grafting of a novel gold(III) complex on nanoporous MCM-41 and evaluation of its toxicity in Saccharomyces cerevisiae.

    PubMed

    Fazaeli, Yousef; Amini, Mostafa M; Ashourion, Hamed; Heydari, Homayoun; Majdabadi, Abbas; Jalilian, Amir Reza; Abolmaali, Shamsozoha

    2011-01-01

    The goal of this research was to investigate the potential of newly synthesized gold complex trichloro(2,4,6-trimethylpyridine)Au(III) as an anticancer agent. The gold(III) complex was synthesized and grafted on nanoporous silica, MCM-41, to produce AuCl(3)@PF-MCM- 41 (AuCl(3) grafted on pyridine-functionalized MCM-41). The toxicity of trichloro(2,4,6- trimethylpyridine)Au(III) and AuCl(3)@PF-MCM-41 in Saccharomyces cerevisiae (as a model system) was studied. The gold(III) complex showed a mid cytotoxic effect on yeast viability. Using the drug delivery system, nanoporous MCM-41, the gold(III) complex became a strong inhibitor for growth of yeast cells at a very low concentration. Furthermore, the animal tests revealed a high uptake of AuCl(3)@PF-MCM-41 in tumor cells. The stability of the compound was confirmed in human serum.

  18. Photodegradation of propranolol by Fe(III)-citrate complexes: kinetics, mechanism and effect of environmental media.

    PubMed

    Chen, Yong; Liu, Zizheng; Wang, Zongping; Xue, Miaomiao; Zhu, Xianchen; Tao, Tao

    2011-10-30

    Photogeneration of HO was optimized in Fe(III)-citrate solution within the pH range of 3.0-9.0 to investigate its photoreactivity at neutral pH without the addition of H(2)O(2) under simulated sunlight. The generation of HO decreased with increasing pH within the range of 6.0-9.0 at the Fe(III)-to-citrate ratio of 10:50 (10(-6)M). However, when the concentration of citrate increased to 1.5 × 10(-4)M, the formation rate of HO increased in the order of pH 9.0<3.0<7.0<4.0<5.0. The pH-dependent HO production was governed by the stability of Fe(II)/Fe(II)-citrate and the amount of O(2)(-) in the solution. Propranolol can be efficiently photodegraded in Fe(III)-citrate system at pH 7.0 with pseudo-first-order constant 3.1 × 10(-4)s(-1). HO was verified to be the main reactive oxygen species (ROS) responsible for the photodegradation of propranolol. The presence of metal ions inhibited the Fe(III)-cit-induced photodegradation in the order of Mn(2+)>Cu(2+)>Ca(2+)>Mg(2+). Both humic acid (HA) and fulvic acid (FA) markedly suppressed the degradation of propranolol. Moreover, the iron in Fe(III)-citrate system was reused by a simple addition of citrate to the reaction solution. By GC-MS analysis, the photoproducts of the propranolol were identified and the degradation pathway was proposed. This work suggests that Fe(III)-citrate complexes are good alternative for the advanced treatment of organic pollutants at neutral pH in aqueous solution. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Circular and Chainlike Copper(II)-Lanthanide(III) Complexes Generated by Assembly Reactions of Racemic and Chiral Copper(II) Cross-Linking Ligand Complexes with Ln(III)(NO3)3·6H2O (Ln(III) = Gd(III), Tb(III), Dy(III)).

    PubMed

    Ueno, Takahiro; Fujinami, Takeshi; Matsumoto, Naohide; Furusawa, Masaki; Irie, Ryo; Re, Nazzareno; Kanetomo, Takuya; Ishida, Takayuki; Sunatsuki, Yukinari

    2017-02-06

    The 1:1 assembly reaction of the racemic form of the cross-linking ligand complex Na[Cu(II)L(dpen(1R2R/1S2S))] with Ln(III)(NO3)3·6H2O gave the centrosymmetric circular (Cu(II)Ln(III))2 complex [Cu(II)L(dpen(1R2R/1S2S))Ln(III)(NO3)2]2 (1Ln: Ln = Gd, Tb, Dy), while the reaction of the enantiopure form Na[Cu(II)L(dpen(1R2R))] with Ln(III)(NO3)3·6H2O gave the chiral chainlike (Cu(II)Ln(III))1∞ complex [Cu(II)L(dpen(1R2R))Ln(III)(NO3)2(CH3CN)]1∞·CH3CN (2Ln: Ln = Gd, Tb, Dy), where {Cu(II)L(dpen(1R2R))}(-) is (N-((1R,2R)-2-(((E)-3-ethoxy-2-oxybenzylidene)amino)-1,2-diphenylethyl)-2-oxybenzamide)copper(II) and {Cu(II)L(dpen(1R2R/1S2S))}(-) is the racemic mixture of {Cu(II)L(dpen(1R2R))}(-) and {Cu(II)L(dpen(1S2S))}(-). The copper(II) component functions as a cross-linking ligand complex and bridges two Ln(III) ions at two phenoxo oxygen atoms and one ethoxy oxygen atom, as well as at an amido oxygen atom. For 1Ln, two binuclear species of [Cu(II)L(dpen(1R2R))Ln(III)(NO3)2] and [Cu(II)L(dpen(1S2S))Ln(III)(NO3)2] with opposite chiralities are linked by two amido oxygen atoms O3 and O3* to form a centrosymmetric circular structure with Gd-Cu = 3.370(1) Å and Gd-Cu* = 5.627(1) Å. For 2Ln, binuclear species with the same chirality are bridged by Gd-O3* = 2.228(5) Å to form a chiral chainlike structure with Gd-Cu = 3.3348(9) Å and Gd-Cu* = 6.2326(9) Å. The bridged angles through the amido group of Gd-O3*═C7* are 133.9(5) and 177.6(4)° for 1Gd and 2Gd, respectively. The magnetic susceptibilities of 1Gd and 2Gd were analyzed by the spin-only Hamiltonian on the basis of the circular tetranuclear (-Cu(II)Gd(III)-)2 and linear chainlike (-Cu(II)Gd(III)-)1∞ structures, respectively. The Cu(II)-Gd(III) magnetic interactions through two phenoxo bridges and a three-atom N-C═O bridge, J1 and J2, are both ferromagnetic to be J1 = +4.6 cm(-1) and J2 = +1.8 cm(-1) for 1Gd and J1 = +4.2 cm(-1) and J2 = +0.037 cm(-1) for 2Gd. The J2 value of 2Gd is much smaller than that

  20. Synthesis and Mossbauer spectroscopy of macrocyclic complexes of iron(III)

    NASA Astrophysics Data System (ADS)

    Mishra, A.; Sura, Kamaljeet S.; Sharma, P.

    2016-10-01

    The article deals with a fresh series of the complexes of the type: [Fe(III)(TML)Cl]Cl2; where TML is a tetra-dentate macrocyclic ligand; has been synthesized by condensation of o-phenylenediamine, diethyl malonate and diazonium ion in the ethanolic medium, through refluxing with FeCl3.The synthesized metal complexes were characterized by Mossbauer spectroscopy. Mossbauer measurements were carried out using standard PC-based spectrometer equipped with Weissel velocity drive operating in the constant acceleration mode. Mossbauer study interprets paramagnetic nature of complexes. Mossbauer measurement of complex 1 and 2 has been taken to find out the value of isomer shift and quadrapole splitting and oxidation state after complaxsation.

  1. DNA interactions of cobalt(III) mixed-polypyridyl complexes containing asymmetric ligands.

    PubMed

    Wang, Xiang-Li; Chao, Hui; Li, Hong; Hong, Xian-Lan; Liu, Yun-Jun; Tan, Li-Feng; Ji, Liang-Nian

    2004-06-01

    Three novel asymmetric ligands, 3-(pyridine-2-yl)-5,6-diphenyl-as-triazine (pdtb), 3-(pyridine-2-yl)-as-triazino[5,6-f]acenaphthylene (pdta) and 3-(pyridine-2-yl)-as-triazino[5,6-f]phenanthroline (pdtp) and their cobalt(III) complexes have been synthesized and characterized. Binding of the three complexes with calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods, viscosity, cyclic voltammetry, and electrophoresis measurements. The experimental results indicate that the size and shape of the intercalated ligand have a marked effect on the binding affinity of complexes to CT-DNA. Complexes 2 and 3 have also been found to promote cleavage of plasmid pBR322 DNA from the supercoiled form I to the open circular form II upon irradiation.

  2. Determination of Judd-Ofelt intensity parameters of pure samarium(III) complexes.

    PubMed

    Monteiro, Jorge Henrique Santos Klier; Mazali, Italo Odone; Sigoli, Fernando Aparecido

    2011-11-01

    This work reports an alternative aproach to obtain the Judd-Ofelt intensity parameters of Sm(III) complexes with the general formula: [Sm(tta)(3)(L)(n)], with L = H(2)O, triphenylphosphine oxide (tppo), 2,2'-bipyridine (bipy) and 1,10-phenantroline (phen); n = 2 for H(2)O and tppo and n = 1 for phen and bipy, using the absorption spectra of rare earth complexes where the powders are dispersed in KBr pellets. This approach can be applied to other complexes of rare earth ions that have spin allowed transitions and it is validated by comparing the emission spectra of the complexes with those dispersed in KBr pellets.

  3. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide

    NASA Astrophysics Data System (ADS)

    Kharchenko, Valerii I.; Kurbatov, Ilya A.; Cherednichenko, Alexander I.; Mirochnik, Anatoly G.; Zhikhareva, Polina A.

    2017-03-01

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb3 + ion (transitions 5D4 → 7FJ, J = 3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  4. Electronic structure and spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide.

    PubMed

    Kharchenko, Valerii I; Kurbatov, Ilya A; Cherednichenko, Alexander I; Mirochnik, Anatoly G; Zhikhareva, Polina A

    2017-03-05

    Spectral properties of terbium(III) nitrate complex with hexamethylphosphoramide have been studied by quantum-chemical methods within the density functional theory and methods of luminescent and X-ray photoelectron spectroscopy. Analysis of the luminescence excitation spectrum of the complex has indicated the absence of intramolecular transfer of electronic excitation energy from the ligand levels to the resonance levels of the rare earth central ion, so luminescence of the complex is associated with the electronic f-f-transitions of Tb(3+) ion (transitions (5)D4→(7)FJ, J=3-6). According to quantum-chemical modeling of the excited singlet and triplet levels of the complex, the excitation energy transfer from the ligands onto the central ion does not occur because of the significant difference of energies of their excited states.

  5. Speciation of organic-soluble europium(III) α1-Wells-Dawson complexes.

    PubMed

    Burton-Pye, Benjamin P; Francesconi, Lynn C

    2011-05-07

    In this contribution, we provide a comprehensive understanding of the speciation of the Eu(III) complex of the lacunary Wells-Dawson isomer, α1-[P(2)W(17)O(61)](10-) in organic media. The Wells-Dawson polyoxometalate, α1-[P(2)W(17)O(61)](10-) (abbreviated as α1) forms well-defined complexes with europium(III) (and other lanthanide(III)) ions in aqueous solution of predominantly 1 : 1 stoichiometries. The 8-coordinate Eu(III) ion is bound to 4 basic terminal oxygens (O(α1)) and four water molecules (O(H(2)O)) that complete the coordination sphere. Tetra-n-butylammonium (TBA) cations are employed to render the [(H(2)O)(4)Eu(α1-P(2)W(17)O(61))](7-) (Eu-α1) complex soluble in acetonitrile. Europium(III) provides the unique opportunity to employ luminescence spectroscopy and multinuclear NMR to probe the coordination environment. We interrogate the innermost coordination sphere of the Eu(III) ion in acetonitrile solution and in MeCN/H(2)O mixtures. We provide evidence toward the fractional displacement and coordination of acetonitrile within the TBA salts, that is consistent with recent EXAFS data. (31)P NMR and Stern-Volmer quenching studies suggest that dimerization to the 2 : 2 species is negligible in acetonitrile and MeCN-H(2)O mixtures. The decreasing transition energy in the excitation spectroscopy of the TBA-Eu-α1 analog upon dilution is consistent with a nephelauxetic effect, which is attributed to a slight increase in covalency upon replacement of water with acetonitrile. Determination of the number of bound waters (q) is also consistent with acetonitrile-water exchange. The reactivity of the 1 : 1 TBA-Eu-α1 with heterocyclic aromatic amines (1,10-phenanthroline, phen, and 2,2' bipyridine, bipy) in MeCN was probed by titrations monitoring the Eu(III) emission upon sensitization by the "antenna ligands". Binding constants for the products 1 : 1 TBA(x-y)H(y)[(Phen)(H(2)O)(2)Eu(α1-P(2)W(17)O(61))] and 1 : 2 TBA(x-y)H(y)[(Phen)(2)Eu(α1-P(2)W(17)O(61

  6. Synthesis, characterization, and reactivity of a side-on manganese(iii)-peroxo complex bearing a pentadentate aminopyridine ligand.

    PubMed

    Du, Junyi; Xu, Daqian; Zhang, Chunxi; Xia, Chungu; Wang, Yong; Sun, Wei

    2016-06-21

    A manganese(ii) complex has been prepared with a proline-derived pentadentate ligand (Pro3Py), and it can be converted to a peroxomanganese(iii) complex in the presence of H2O2 and triethylamine. The resulting peroxomanganese(iii) complex was well characterised by UV-vis, EPR and ESI-MS techniques, and the geometric structure was discussed based on DFT calculations.

  7. Cytotoxic and genotoxic potential of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA complex in human hepatoma (HepG2) cells.

    PubMed

    Novotnik, Breda; Ščančar, Janez; Milačič, Radmila; Filipič, Metka; Žegura, Bojana

    2016-07-01

    Chromium (Cr) and ethylenediaminetetraacetate (EDTA) are common environmental pollutants and can be present in high concentrations in surface waters at the same time. Therefore, chelation of Cr with EDTA can occur and thereby stable Cr(III)-EDTA complex is formed. Since there are no literature data on Cr(III)-EDTA toxicity, the aim of our work was to evaluate and compare Cr(III)-EDTA cytotoxic and genotoxic activity with those of Cr(VI) and Cr(III)-nitrate in human hepatoma (HepG2) cell line. First the effect of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on cell viability was studied in the concentration range from 0.04 μg mL(-1) to 25 μg mL(-1) after 24 h exposure. Further the influence of non-cytotoxic concentrations of Cr(VI), Cr(III)-nitrate and Cr(III)-EDTA on DNA damage and genomic stability was determined with the comet assay and cytokinesis block micronucleus cytome assay, respectively. Cell viability was decreased only by Cr(VI) at concentrations above 1.0 μg mL(-1). Cr(VI) at ≥0.2 μg mL(-1) and Cr(III) at ≥1.0 μg mL(-1) induced DNA damage, while after Cr(III)-EDTA exposure no formation DNA strand breaks was determined. Statistically significant formation of micronuclei was induced only by Cr(VI) at ≥0.2 μg mL(-1), while no influence on the frequency of nuclear buds nor nucleoplasmic bridges was observed at any exposure. This study provides the first evidence that Cr(III)-EDTA did not induce DNA damage and had no influence on the genomic stability of HepG2 cells.

  8. Structural and electronic dependence of the single-molecule-magnet behavior of dysprosium(III) complexes.

    PubMed

    Campbell, Victoria E; Bolvin, Hélène; Rivière, Eric; Guillot, Regis; Wernsdorfer, Wolfgang; Mallah, Talal

    2014-03-03

    We investigate and compare the magnetic properties of two isostructural Dy(III)-containing complexes. The Dy(III) ions are chelated by hexadentate ligands and possess two apical bidendate nitrate anions. In dysprosium(III) N,N'-bis(imine-2-yl)methylene-1,8-diamino-3,6-dioxaoctane (1), the ligand's donor atoms are two alkoxo, two pyridine, and two imine nitrogen atoms. Dysprosium(III) N,N'-bis(amine-2-yl)methylene-1,8-diamino-3,6-dioxaoctane (2) is identical with 1 except for one modification: the two imine groups have been replaced by amine groups. This change has a minute effect on the structure and a larger effect the magnetic behavior. The two complexes possess slow relaxation of the magnetization in the presence of an applied field of 1000 Oe but with a larger barrier for reorientation of the magnetization for 1 (Ueff/kB = 50 K) than for 2 (Ueff/kB = 34 K). First-principles calculations using the spin-orbit complete active-space self-consistent-field method were performed and allowed to fit the experimental magnetization data. The calculations gave the energy spectrum of the 2J + 1 sublevels issued from the J = 15/2 free-ion ground state. The lowest-lying sublevels were found to have a large contribution of MJ = ±15/2 for 1, while for 2, MJ = ±13/2 was dominant. The observed differences were attributed to a synergistic effect between the electron density of the ligand and the small structural changes provoked by a slight alteration of the coordination environment. It was observed that the stronger ligand field (imine) resulted in complex 1 with a larger energy barrier for reorientation of the magnetization than 2.

  9. Crystallization of Mitochondrial Respiratory Complex II fromChicken Heart: A Membrane-Protein Complex Diffracting to 2.0Angstrom

    SciTech Connect

    Huang, Li-shar; Borders, Toni M.; Shen, John T.; Wang, Chung-Jen; Berry, Edward A.

    2004-12-17

    Procedure is presented for preparation of diffraction-quality crystals of a vertebrate mitochondrial respiratory Complex II. The crystals have the potential to diffract to at least 2.0 Angstrom with optimization of post-crystal-growth treatment and cryoprotection. This should allow determination of the structure of this important and medically relevant membrane protein complex at near-atomic resolution and provide great detail of the mode of binding of substrates and inhibitors at the two substrate-binding sites.

  10. Gd(III) complexes for electron-electron dipolar spectroscopy: Effects of deuteration, pH and zero field splitting

    NASA Astrophysics Data System (ADS)

    Garbuio, Luca; Zimmermann, Kaspar; Häussinger, Daniel; Yulikov, Maxim

    2015-10-01

    Spectral parameters of Gd(III) complexes are intimately linked to the performance of the Gd(III)-nitroxide or Gd(III)-Gd(III) double electron-electron resonance (DEER or PELDOR) techniques, as well as to that of relaxation induced dipolar modulation enhancement (RIDME) spectroscopy with Gd(III) ions. These techniques are of interest for applications in structural biology, since they can selectively detect site-to-site distances in biomolecules or biomolecular complexes in the nanometer range. Here we report relaxation properties, echo detected EPR spectra, as well as the magnitude of the echo reduction effect in Gd(III)-nitroxide DEER for a series of Gadolinium(III) complexes with chelating agents derived from tetraazacyclododecane. We observed that solvent deuteration does not only lengthen the relaxation times of Gd(III) centers but also weakens the DEER echo reduction effect. Both of these phenomena lead to an improved signal-to-noise ratios or, alternatively, longer accessible distance range in pulse EPR measurements. The presented data enrich the knowledge on paramagnetic Gd(III) chelate complexes in frozen solutions, and can help optimize the experimental conditions for most types of the pulse measurements of the electron-electron dipolar interactions.

  11. Synthesis, Characterization, DNA Interaction, and Antitumor Activities of La (III) Complex with Schiff Base Ligand Derived from Kaempferol and Diethylenetriamine

    PubMed Central

    Wang, Qin; Huang, Yu; Zhang, Jin-Sheng; Yang, Xin-Bin

    2014-01-01

    A novel La (III) complex, [LaL(H2O)3]NO3·3H2O, with Schiff base ligand L derived from kaempferol and diethylenetriamine, has been synthesized and characterized by elemental analysis, IR, UV-visible, 1H NMR, thermogravimetric analysis, and molar conductance measurements. The fluorescence spectra, circular dichroism spectra, and viscosity measurements and gel electrophoresis experiments indicated that the ligand L and La (III) complex could bind to CT-DNA presumably via intercalative mode and the La (III) complex showed a stronger ability to bind and cleave DNA than the ligand L alone. The binding constants (Kb) were evaluated from fluorescence data and the values ranged from 0.454 to 0.659 × 105 L mol−1 and 1.71 to 17.3 × 105 L mol−1 for the ligand L and La (III) complex, respectively, in the temperature range of 298–310 K. It was also found that the fluorescence quenching mechanism of EB-DNA by ligand L and La (III) complex was a static quenching process. In comparison to free ligand L, La (III) complex exhibited enhanced cytotoxic activities against tested tumor cell lines HL-60 and HepG-2, which may correlate with the enhanced DNA binding and cleaving abilities of the La (III) complex. PMID:25371657

  12. Fluorescent and ultraviolet-visible spectroscopy studies on the antioxidation and DNA binding properties of binuclear Tb(III) complexes.

    PubMed

    Liu, Yongchun; Jiang, Xinhui; Yang, Zhengyin; Zheng, Xudong; Liu, Jianning; Zhou, Tianlin

    2010-09-01

    Tb(III) complexes were prepared from Tb(NO(3))(3)·6H(2)O and four Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde with aroylhydrazines. X-ray crystal and other structural analyses indicate that Tb(III) and every ligand can form a binuclear Tb(III) complex with 1:1 metal-to-ligand stoichiometry and nine-coordination at the Tb(III) center. Viscosity titration experiments and fluorescent and ultraviolet-visible (UV-Vis) spectroscopy results indicate that all the Tb(III) complexes can bind to Calf thymus DNA through intercalation with the binding constants at the order of magnitude of 10(6)-10(7) M(-1), and they may be used as potential anticancer drugs, but complexes containing active phenolic hydroxy groups may have stronger antitumor activities. Antioxidation results indicate that all the Tb(III) complexes have strong abilities of scavenging hydroxyl radicals and superoxide radicals, but complexes containing active phenolic hydroxy groups show stronger scavenging effects on hydroxyl radicals and complexes containing N-heteroaromatic substituent show stronger scavenging effects on superoxide radicals. However, Tb(III) emission with these systems is not observed, for these ligands rather are quenchers and unable to sensitize this metal ion.

  13. The structures of CyMe4-BTBP complexes of americium(iii) and europium(iii) in solvents used in solvent extraction, explaining their separation properties.

    PubMed

    Ekberg, Christian; Löfström-Engdahl, Elin; Aneheim, Emma; Foreman, Mark R StJ; Geist, Andreas; Lundberg, Daniel; Denecke, Melissa; Persson, Ingmar

    2015-11-14

    Separation of trivalent actinoid (An(iii)) and lanthanoid (Ln(iii)) ions is extremely challenging due to their similar ionic radii and chemical properties. Poly-aromatic nitrogen compounds acting as tetradentate chelating ligands to the metal ions in the extraction, have the ability to sufficiently separate An(iii) from Ln(iii). One of these compounds, 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzol[1,2,4]triazin-3-yl)[2,2]bipyridine, CyMe4-BTBP, has proven to be resistant towards acidic environments and strong radiation from radioactive decomposition. EXAFS studies of the dicomplexes of CyMe4-BTBP with americium(iii) and europium(iii) in nitrobenzene, cyclohexanone, 1-hexanol, 1-octanol and malonamide (DMDOHEMA) in 1-octanol have been carried out to get a deeper understanding of the parameters responsible for the separation. The predominating complexes independent of solvent used are [Am(CyMe4-BTBP)2(NO3)](2+) and [Eu(CyMe4-BTBP)2](3+), respectively, which are present as outer-sphere ion-pairs with nitrate ions in the studied solvents with low relative permittivity. The presence of a nitrate ion in the first coordination sphere of the americium(iii) complex compensates the charge density of the complex considerably in comparison when only outer-sphere ion-pairs are formed as for the [Eu(CyMe4-BTBP)2](3+) complex. The stability and solubility of a complex in a solvent with low relative permittivity increase with decreasing charge density. The [Am(CyMe4-BTBP)2(NO3)](2+) complex will therefore be increasingly soluble and stabilized over the [Eu(CyMe4-BTBP)2](3+) complex in solvents with decreasing relative permittivity of the solvent. The separation of americium(iii) from europium(iii) with CyMe4-BTBP as extraction agent will increase with decreasing relative permittivity of the solvent, and thereby also with decreasing solubility of CyMe4-BTBP. The choice of solvent is therefore a balance of a high separation factor and sufficient solubility of the CyMe4-BTBP

  14. Integrated Investigation on the Production and Fate of Organo-Cr(III) Complexes from Microbial Reduction of Chromate

    SciTech Connect

    Xun, Luying

    2005-06-01

    Our objective is to investigate the complexity of chromium biogeocycling. Our results clearly support more complexity. In short, the chromium cycle is not as simple as the conversion between Cr(III) and Cr(VI) in inorganic forms. We have obtained more evidence to prove the formation of soluble organo-Cr(III) complexes from microbial reduction of Cr(VI). The complexes are relatively stable due to the slow ligand exchange of Cr(III). However, some microorganisms can consume the organic ligands and release Cr(III), which then precipitates. Efforts are being made to characterize the organo-Cr(III) complexes and investigate their behavior in soil. Progress and efforts are summarized for each task. Task 1. Production of soluble organo-Cr(III) complexes by selected microorganisms A total of eight organisms were screened for production of soluble organo-Cr(III) complexes by culturing in both growth and non growth media containing 4 mg/L of Cr(VI); three were Gram positive and five were Gram negative. The Gram-positive bacteria were Cellulomonas sp. ES 6, Rhodococcus sp., and Leafsonia sp., while Shewanella oneidensis MR 1, Desulfovibrio desulfuricans G20, D. vulgaris Hildenborough, Pseudomonas putida MK 1 and Ps. aeruginosa PAO 1 were Gram negative. Purifications of the soluble organo-Cr(III) complexes produced by Cellulomonas sp. ES 6, Shewanella. oneidensis MR 1, Rhodococcus sp., and D. vulgaris Hildenborough were carried out. The culture supernatants were lyophilized and extracted first with methanol followed by water. The extracts were then analyzed for soluble Cr. The majority of the Cr(III) was present in the water-soluble fraction for all of the bacteria tested (data not shown), revealing a general phenomenon of soluble Cr(III) production. Cellulomonas sp. ES6 produced the highest amount of soluble Cr(III) (364 ppm) and D. vulgaris Hildenborough produced the least (143 ppm). Seventy eight percent of the soluble Cr(III) produced by Shewanella. oneidensis MR 1 was

  15. Mn(II) Oxidation by the Multicopper Oxidase Complex Mnx: A Coordinated Two-Stage Mn(II)/(III) and Mn(III)/(IV) Mechanism.

    PubMed

    Soldatova, Alexandra V; Romano, Christine A; Tao, Lizhi; Stich, Troy A; Casey, William H; Britt, R David; Tebo, Bradley M; Spiro, Thomas G

    2017-08-23

    The bacterial manganese oxidase MnxG of the Mnx protein complex is unique among multicopper oxidases (MCOs) in carrying out a two-electron metal oxidation, converting Mn(II) to MnO2 nanoparticles. The reaction occurs in two stages: Mn(II) → Mn(III) and Mn(III) → MnO2. In a companion study , we show that the electron transfer from Mn(II) to the low-potential type 1 Cu of MnxG requires an activation step, likely forming a hydroxide br