WorldWideScience

Sample records for diferric-tyrosyl radical cofactor

  1. Escherichia coli class Ib ribonucleotide reductase contains a dimanganese(III)-tyrosyl radical cofactor in vivo†

    Science.gov (United States)

    Cotruvo, Joseph A.; Stubbe, JoAnne

    2011-01-01

    Escherichia coli class Ib ribonucleotide reductase (RNR) converts nucleoside 5′-diphosphates to deoxynucleoside 5′-diphosphates in iron-limited and oxidative stress conditions. We have recently demonstrated in vitro that this RNR is active with both diferric-tyrosyl radical (FeIII2-Y•) and dimanganese(III)-Y• (MnIII2-Y•) cofactors in the β2 subunit, NrdF [Cotruvo J.A., Jr. and Stubbe J., Biochemistry (2010) 49, 1297–1309]. Here we demonstrate, by purification of this protein from its endogenous levels in an E. coli strain deficient in its five known iron uptake pathways and grown under iron-limited conditions, that the MnIII2-Y• cofactor is assembled in vivo. This is the first definitive determination of the active cofactor of a class Ib RNR purified from its native organism without overexpression. From 88 g of cell paste, 150 μg of NrdF was isolated with ~95% purity, with 0.2 Y•/β2, 0.9 Mn/β2, and a specific activity of 720 nmol/min/mg. In these conditions, the class Ib RNR is the primary active RNR in the cell. Our results strongly suggest that E. coli NrdF is an obligate manganese protein in vivo and that the MnIII2-Y• cofactor assembly pathway we have identified in vitro involving the flavodoxin-like protein NrdI, present inside the cell at catalytic levels, is operative in vivo. PMID:21250660

  2. Streptococcus sanguinis class Ib ribonucleotide reductase: high activity with both iron and manganese cofactors and structural insights.

    Science.gov (United States)

    Makhlynets, Olga; Boal, Amie K; Rhodes, Delacy V; Kitten, Todd; Rosenzweig, Amy C; Stubbe, JoAnne

    2014-02-28

    Streptococcus sanguinis is a causative agent of infective endocarditis. Deletion of SsaB, a manganese transporter, drastically reduces S. sanguinis virulence. Many pathogenic organisms require class Ib ribonucleotide reductase (RNR) to catalyze the conversion of nucleotides to deoxynucleotides under aerobic conditions, and recent studies demonstrate that this enzyme uses a dimanganese-tyrosyl radical (Mn(III)2-Y(•)) cofactor in vivo. The proteins required for S. sanguinis ribonucleotide reduction (NrdE and NrdF, α and β subunits of RNR; NrdH and TrxR, a glutaredoxin-like thioredoxin and a thioredoxin reductase; and NrdI, a flavodoxin essential for assembly of the RNR metallo-cofactor) have been identified and characterized. Apo-NrdF with Fe(II) and O2 can self-assemble a diferric-tyrosyl radical (Fe(III)2-Y(•)) cofactor (1.2 Y(•)/β2) and with the help of NrdI can assemble a Mn(III)2-Y(•) cofactor (0.9 Y(•)/β2). The activity of RNR with its endogenous reductants, NrdH and TrxR, is 5,000 and 1,500 units/mg for the Mn- and Fe-NrdFs (Fe-loaded NrdF), respectively. X-ray structures of S. sanguinis NrdIox and Mn(II)2-NrdF are reported and provide a possible rationale for the weak affinity (2.9 μM) between them. These streptococcal proteins form a structurally distinct subclass relative to other Ib proteins with unique features likely important in cluster assembly, including a long and negatively charged loop near the NrdI flavin and a bulky residue (Thr) at a constriction in the oxidant channel to the NrdI interface. These studies set the stage for identifying the active form of S. sanguinis class Ib RNR in an animal model for infective endocarditis and establishing whether the manganese requirement for pathogenesis is associated with RNR.

  3. Radical S-adenosylmethionine (SAM) enzymes in cofactor biosynthesis: a treasure trove of complex organic radical rearrangement reactions.

    Science.gov (United States)

    Mehta, Angad P; Abdelwahed, Sameh H; Mahanta, Nilkamal; Fedoseyenko, Dmytro; Philmus, Benjamin; Cooper, Lisa E; Liu, Yiquan; Jhulki, Isita; Ealick, Steven E; Begley, Tadhg P

    2015-02-13

    In this minireview, we describe the radical S-adenosylmethionine enzymes involved in the biosynthesis of thiamin, menaquinone, molybdopterin, coenzyme F420, and heme. Our focus is on the remarkably complex organic rearrangements involved, many of which have no precedent in organic or biological chemistry. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Cofactor Editing by the G-protein Metallochaperone Domain Regulates the Radical B12 Enzyme IcmF.

    Science.gov (United States)

    Li, Zhu; Kitanishi, Kenichi; Twahir, Umar T; Cracan, Valentin; Chapman, Derrell; Warncke, Kurt; Banerjee, Ruma

    2017-03-10

    IcmF is a 5'-deoxyadenosylcobalamin (AdoCbl)-dependent enzyme that catalyzes the carbon skeleton rearrangement of isobutyryl-CoA to butyryl-CoA. It is a bifunctional protein resulting from the fusion of a G-protein chaperone with GTPase activity and the cofactor- and substrate-binding mutase domains with isomerase activity. IcmF is prone to inactivation during catalytic turnover, thus setting up its dependence on a cofactor repair system. Herein, we demonstrate that the GTPase activity of IcmF powers the ejection of the inactive cob(II)alamin cofactor and requires the presence of an acceptor protein, adenosyltransferase, for receiving it. Adenosyltransferase in turn converts cob(II)alamin to AdoCbl in the presence of ATP and a reductant. The repaired cofactor is then reloaded onto IcmF in a GTPase-gated step. The mechanistic details of cofactor loading and offloading from the AdoCbl-dependent IcmF are distinct from those of the better characterized and homologous methylmalonyl-CoA mutase/G-protein chaperone system. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Lanthanide Cofactors for Triphosphorylation Ribozymes

    Science.gov (United States)

    Sweeney, K. J.; Müller, U. F.

    2017-07-01

    RNA world organisms could have used trimetaphosphate as energy source for thermodynamically unfavorable RNA polymerization. Using in vitro selection we show here that Lanthanides can serve as cofactors for ribozyme-catalyzed RNA triphosphorylation.

  6. Spectroscopic Evidence for a H Bond Network at Y356 Located at the Subunit Interface of Active E. coli Ribonucleotide Reductase.

    Science.gov (United States)

    Nick, Thomas U; Ravichandran, Kanchana R; Stubbe, JoAnne; Kasanmascheff, Müge; Bennati, Marina

    2017-07-18

    The reaction catalyzed by E. coli ribonucleotide reductase (RNR) composed of α and β subunits that form an active α2β2 complex is a paradigm for proton-coupled electron transfer (PCET) processes in biological transformations. β2 contains the diferric tyrosyl radical (Y 122 ·) cofactor that initiates radical transfer (RT) over 35 Å via a specific pathway of amino acids (Y 122 · ⇆ [W 48 ] ⇆ Y 356 in β2 to Y 731 ⇆ Y 730 ⇆ C 439 in α2). Experimental evidence exists for colinear and orthogonal PCET in α2 and β2, respectively. No mechanistic model yet exists for the PCET across the subunit (α/β) interface. Here, we report unique EPR spectroscopic features of Y 356 ·-β, the pathway intermediate generated by the reaction of 2,3,5-F 3 Y 122 ·-β2/CDP/ATP with wt-α2, Y 731 F-α2, or Y 730 F-α2. High field EPR (94 and 263 GHz) reveals a dramatically perturbed g tensor. [ 1 H] and [ 2 H]-ENDOR reveal two exchangeable H bonds to Y 356 ·: a moderate one almost in-plane with the π-system and a weak one. DFT calculation on small models of Y· indicates that two in-plane, moderate H bonds (r O-H ∼1.8-1.9 Å) are required to reproduce the g x value of Y 356 · (wt-α2). The results are consistent with a model, in which a cluster of two, almost symmetrically oriented, water molecules provide the two moderate H bonds to Y 356 · that likely form a hydrogen bond network of water molecules involved in either the reversible PCET across the subunit interface or in H + release to the solvent during Y 356 oxidation.

  7. Optimization Strategies for Hardware-Based Cofactorization

    Science.gov (United States)

    Loebenberger, Daniel; Putzka, Jens

    We use the specific structure of the inputs to the cofactorization step in the general number field sieve (GNFS) in order to optimize the runtime for the cofactorization step on a hardware cluster. An optimal distribution of bitlength-specific ECM modules is proposed and compared to existing ones. With our optimizations we obtain a speedup between 17% and 33% of the cofactorization step of the GNFS when compared to the runtime of an unoptimized cluster.

  8. Cofactor engineering for advancing chemical biotechnology.

    Science.gov (United States)

    Wang, Yipeng; San, Ka-Yiu; Bennett, George N

    2013-12-01

    Cofactors provide redox carriers for biosynthetic reactions, catabolic reactions and act as important agents in transfer of energy for the cell. Recent advances in manipulating cofactors include culture conditions or additive alterations, genetic modification of host pathways for increased availability of desired cofactor, changes in enzyme cofactor specificity, and introduction of novel redox partners to form effective circuits for biochemical processes and biocatalysts. Genetic strategies to employ ferredoxin, NADH and NADPH most effectively in natural or novel pathways have improved yield and efficiency of large-scale processes for fuels and chemicals and have been demonstrated with a variety of microbial organisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Streptococcus sanguinis Class Ib Ribonucleotide Reductase

    Science.gov (United States)

    Makhlynets, Olga; Boal, Amie K.; Rhodes, DeLacy V.; Kitten, Todd; Rosenzweig, Amy C.; Stubbe, JoAnne

    2014-01-01

    Streptococcus sanguinis is a causative agent of infective endocarditis. Deletion of SsaB, a manganese transporter, drastically reduces S. sanguinis virulence. Many pathogenic organisms require class Ib ribonucleotide reductase (RNR) to catalyze the conversion of nucleotides to deoxynucleotides under aerobic conditions, and recent studies demonstrate that this enzyme uses a dimanganese-tyrosyl radical (MnIII2-Y•) cofactor in vivo. The proteins required for S. sanguinis ribonucleotide reduction (NrdE and NrdF, α and β subunits of RNR; NrdH and TrxR, a glutaredoxin-like thioredoxin and a thioredoxin reductase; and NrdI, a flavodoxin essential for assembly of the RNR metallo-cofactor) have been identified and characterized. Apo-NrdF with FeII and O2 can self-assemble a diferric-tyrosyl radical (FeIII2-Y•) cofactor (1.2 Y•/β2) and with the help of NrdI can assemble a MnIII2-Y• cofactor (0.9 Y•/β2). The activity of RNR with its endogenous reductants, NrdH and TrxR, is 5,000 and 1,500 units/mg for the Mn- and Fe-NrdFs (Fe-loaded NrdF), respectively. X-ray structures of S. sanguinis NrdIox and MnII2-NrdF are reported and provide a possible rationale for the weak affinity (2.9 μm) between them. These streptococcal proteins form a structurally distinct subclass relative to other Ib proteins with unique features likely important in cluster assembly, including a long and negatively charged loop near the NrdI flavin and a bulky residue (Thr) at a constriction in the oxidant channel to the NrdI interface. These studies set the stage for identifying the active form of S. sanguinis class Ib RNR in an animal model for infective endocarditis and establishing whether the manganese requirement for pathogenesis is associated with RNR. PMID:24381172

  10. Engineering redox balance through cofactor systems.

    Science.gov (United States)

    Chen, Xiulai; Li, Shubo; Liu, Liming

    2014-06-01

    Redox balance plays an important role in the production of enzymes, pharmaceuticals, and chemicals. To meet the demands of industrial production, it is desirable that microbes maintain a maximal carbon flux towards target metabolites with no fluctuations in redox. This requires functional cofactor systems that support dynamic homeostasis between different redox states or functional stability in a given redox state. Redox balance can be achieved by improving the self-balance of a cofactor system, regulating the substrate balance of a cofactor system, and engineering the synthetic balance of a cofactor system. This review summarizes how cofactor systems can be manipulated to improve redox balance in microbes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Genetic characterization and role in virulence of the ribonucleotide reductases of Streptococcus sanguinis.

    Science.gov (United States)

    Rhodes, DeLacy V; Crump, Katie E; Makhlynets, Olga; Snyder, Melanie; Ge, Xiuchun; Xu, Ping; Stubbe, JoAnne; Kitten, Todd

    2014-02-28

    Streptococcus sanguinis is a cause of infective endocarditis and has been shown to require a manganese transporter called SsaB for virulence and O2 tolerance. Like certain other pathogens, S. sanguinis possesses aerobic class Ib (NrdEF) and anaerobic class III (NrdDG) ribonucleotide reductases (RNRs) that perform the essential function of reducing ribonucleotides to deoxyribonucleotides. The accompanying paper (Makhlynets, O., Boal, A. K., Rhodes, D. V., Kitten, T., Rosenzweig, A. C., and Stubbe, J. (2014) J. Biol. Chem. 289, 6259-6272) indicates that in the presence of O2, the S. sanguinis class Ib RNR self-assembles an essential diferric-tyrosyl radical (Fe(III)2-Y(•)) in vitro, whereas assembly of a dimanganese-tyrosyl radical (Mn(III)2-Y(•)) cofactor requires NrdI, and Mn(III)2-Y(•) is more active than Fe(III)2-Y(•) with the endogenous reducing system of NrdH and thioredoxin reductase (TrxR1). In this study, we have shown that deletion of either nrdHEKF or nrdI completely abolishes virulence in an animal model of endocarditis, whereas nrdD mutation has no effect. The nrdHEKF, nrdI, and trxR1 mutants fail to grow aerobically, whereas anaerobic growth requires nrdD. The nrdJ gene encoding an O2-independent adenosylcobalamin-cofactored RNR was introduced into the nrdHEKF, nrdI, and trxR1 mutants. Growth of the nrdHEKF and nrdI mutants in the presence of O2 was partially restored. The combined results suggest that Mn(III)2-Y(•)-cofactored NrdF is required for growth under aerobic conditions and in animals. This could explain in part why manganese is necessary for virulence and O2 tolerance in many bacterial pathogens possessing a class Ib RNR and suggests NrdF and NrdI may serve as promising new antimicrobial targets.

  12. Genetic Characterization and Role in Virulence of the Ribonucleotide Reductases of Streptococcus sanguinis * ♦

    Science.gov (United States)

    Rhodes, DeLacy V.; Crump, Katie E.; Makhlynets, Olga; Snyder, Melanie; Ge, Xiuchun; Xu, Ping; Stubbe, JoAnne; Kitten, Todd

    2014-01-01

    Streptococcus sanguinis is a cause of infective endocarditis and has been shown to require a manganese transporter called SsaB for virulence and O2 tolerance. Like certain other pathogens, S. sanguinis possesses aerobic class Ib (NrdEF) and anaerobic class III (NrdDG) ribonucleotide reductases (RNRs) that perform the essential function of reducing ribonucleotides to deoxyribonucleotides. The accompanying paper (Makhlynets, O., Boal, A. K., Rhodes, D. V., Kitten, T., Rosenzweig, A. C., and Stubbe, J. (2014) J. Biol. Chem. 289, 6259–6272) indicates that in the presence of O2, the S. sanguinis class Ib RNR self-assembles an essential diferric-tyrosyl radical (FeIII2-Y•) in vitro, whereas assembly of a dimanganese-tyrosyl radical (MnIII2-Y•) cofactor requires NrdI, and MnIII2-Y• is more active than FeIII2-Y• with the endogenous reducing system of NrdH and thioredoxin reductase (TrxR1). In this study, we have shown that deletion of either nrdHEKF or nrdI completely abolishes virulence in an animal model of endocarditis, whereas nrdD mutation has no effect. The nrdHEKF, nrdI, and trxR1 mutants fail to grow aerobically, whereas anaerobic growth requires nrdD. The nrdJ gene encoding an O2-independent adenosylcobalamin-cofactored RNR was introduced into the nrdHEKF, nrdI, and trxR1 mutants. Growth of the nrdHEKF and nrdI mutants in the presence of O2 was partially restored. The combined results suggest that MnIII2-Y•-cofactored NrdF is required for growth under aerobic conditions and in animals. This could explain in part why manganese is necessary for virulence and O2 tolerance in many bacterial pathogens possessing a class Ib RNR and suggests NrdF and NrdI may serve as promising new antimicrobial targets. PMID:24381171

  13. Co-factor activated recombinant adenovirus proteinases

    Science.gov (United States)

    Anderson, Carl W.; Mangel, Walter F.

    1996-08-06

    This application describes methods and expression constructs for producing activatable recombinant adenovirus proteinases. Purified activatable recombinant adenovirus proteinases and methods of purification are described. Activated adenovirus proteinases and methods for obtaining activated adenovirus proteinases are further included. Isolated peptide cofactors of adenovirus proteinase activity, methods of purifying and identifying said peptide cofactors are also described. Antibodies immunoreactive with adenovirus proteinases, immunospecific antibodies, and methods for preparing them are also described. Other related methods and materials are also described.

  14. Replacing Electron Transport Cofactors with Hydrogenases

    KAUST Repository

    Laamarti, Rkia

    2016-12-01

    Enzymes have found applications in a broad range of industrial production processes. While high catalytic activity, selectivity and mild reaction conditions are attractive advantages of the biocatalysts, particularly costs arising from required cofactors pose a sever limitation. While cofactor-recycling systems are available, their use implies constraints for process set-up and conditions, which are a particular problem e.g. for solid-gas-phase reactions. Several oxidoreductases are able to directly exchange electrons with electrodes. Hence, the co-immobilization of both, an electron-utilizing and an electron-generating oxidoreductase on conductive nanoparticles should facilitate the direct electron flow from an enzymatic oxidation to a reduction reaction circumventing redox-cofactors requirements. In such a set-up, hydrogenases could generate and provide electrons directly form gaseous hydrogen. This thesis describes the co-immobilization of the oxygen tolerant hydrogenases from C. eutropha or C. metallidurans and cytochrome P450BM3 as test system. Conductive material in the form of carbon nanotubes (CNT) serves as a suitable support. A combination of the hydrogenase and the catalytic domain of P450BM3 immobilized on carbon nanotubes were tested for the oxidation of lauric acid in the presence of hydrogen instead of an electron-transport cofactor. The GC-MS analysis reveals the conversion of 4% of lauric acid (LA) into three products, which correspond to the hydroxylated lauric acid in three different positions with a total turnover (TON) of 34. The product distribution is similar to that obtained when using the wildtype P450BM3 with the nicotinamide adenine dinucleotide phosphate (NADPH) cofactor. Such electronic coupling couldn’t be achieved for the conversion of other substrates such as propane and cyclohexane, probably due to the high uncoupling rate within the heme-domain of cytochrome P450BM3 when unnatural substrates are introduced.

  15. Enzyme cofactors: Double-edged sword for catalysis

    Science.gov (United States)

    Ivanov, Ivaylo

    2013-01-01

    The metal cofactors responsible for the activity of CDK2 -- a representative member of the kinase superfamily of enzymes -- have now been shown to also have inhibitory effects during the catalytic cycle.

  16. Metabolic and Transcriptional Response to Cofactor Perturbations in Escherichia coli

    DEFF Research Database (Denmark)

    Holm, Anders Koefoed; Blank, L.M.; Oldiges, M.

    2010-01-01

    Metabolic cofactors such as NADH and ATP play important roles in a large number of cellular reactions, and it is of great interest to dissect the role of these cofactors in different aspects of metabolism. Toward this goal, we overexpressed NADH oxidase and the soluble F1-ATPase in Escherichia coli...... of redox and energy metabolism and should help in developing metabolic engineering strategies in E. coli....

  17. Cofactors involved in light-driven charge separation in photosystem I identified by subpicosecond infrared spectroscopy.

    Science.gov (United States)

    Di Donato, Mariangela; Stahl, Andreas D; van Stokkum, Ivo H M; van Grondelle, Rienk; Groot, Marie-Louise

    2011-02-01

    Photosystem I is one of the key players in the conversion of solar energy into chemical energy. While the chlorophyll dimer P(700) has long been identified as the primary electron donor, the components involved in the primary charge separation process in PSI remain undetermined. Here, we have studied the charge separation dynamics in Photosystem I trimers from Synechococcus elongatus by femtosecond vis-pump/mid-infrared-probe spectroscopy upon excitation at 700, 710, and 715 nm. Because of the high specificity of the infrared region for the redox state and small differences in the molecular structure of pigments, we were able to clearly identify specific marker bands indicating chlorophyll (Chl) oxidation. Magnitudes of chlorophyll cation signals are observed to increase faster than the time resolution of the experiment (~0.2 ps) upon both excitation conditions: 700 nm and selective red excitation. Two models, involving either ultrafast charge separation or charge transfer character of the red pigments in PSI, are discussed to explain this observation. A further increase in the magnitudes of cation signals on a subpicosecond time scale (0.8-1 ps) indicates the formation of the primary radical pair. Evolution in the cation region with time constants of 7 and 40 ps reveals the formation of the secondary radical pair, involving a secondary electron donor. Modeling of the data allows us to extract the spectra of the two radical pairs, which have IR signatures consistent with A+A₀- and P₇₀₀+A₁-. We conclude that the cofactor chlorophyll A acts as the primary donor in PSI. The existence of an equilibrium between the two radical pairs we interpret as concerted hole/electron transfer between the pairs of electron donors and acceptors, until after 40 ps, relaxation leads to a full population of the P₇₀₀+A₁. radical pair.

  18. Radical Evil

    Directory of Open Access Journals (Sweden)

    Carlos Manrique

    2007-12-01

    Full Text Available There is an aporia in Kant’s analysis of evil: he defines radical evilas an invisible disposition of the will, but he also demands an inferential connection between visible evil actions and this invisible disposition. This inference,however, undermines the radical invisibility of radical evil according to Kant’s own definition of the latter. Noting how this invisibility of moral worth is a distinctive feature of Kant’s approach to the moral problem, the paper then asks why, in the Groundwork, he nonetheless forecloses a question about evil that seems to be consistent with this approach. It is argued that to account for this aporia and this foreclosure, one has to interrogate the way in which the category of religion orients Kant’s incipient philosophy of history in Die Religion.

  19. Metabolic impact of redox cofactor perturbations in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Hou, Jin; Lages, Nuno; Oldiges, M.

    2009-01-01

    to induce widespread changes in metabolism. We present a detailed analysis of the impact of perturbations in redox cofactors in the cytosol or mitochondria on glucose and energy metabolism in Saccharomyces cerevisiae to aid metabolic engineering decisions that involve cofactor engineering. We enhanced NADH...... oxidation by introducing NADH oxidase or alternative oxidase, its ATP-mediated conversion to NADPH using NADH kinase as well as the interconversion of NADH and NADPH independent of ATP by the soluble, non-proton-translocating bacterial transhydrogenase. Decreasing cytosolic NADH level lowered glycerol...

  20. Quantum mechanics/molecular mechanics studies on the mechanism of action of cofactor pyridoxal 5'-phosphate in ornithine 4,5-aminomutase.

    Science.gov (United States)

    Pang, Jiayun; Scrutton, Nigel S; Sutcliffe, Michael J

    2014-09-01

    A computational study was performed on the experimentally elusive cyclisation step in the cofactor pyridoxal 5'-phosphate (PLP)-dependent D-ornithine 4,5-aminomutase (OAM)-catalysed reaction. Calculations using both model systems and a combined quantum mechanics/molecular mechanics approach suggest that regulation of the cyclic radical intermediate is achieved through the synergy of the intrinsic catalytic power of cofactor PLP and the active site of the enzyme. The captodative effect of PLP is balanced by an enzyme active site that controls the deprotonation of both the pyridine nitrogen atom (N1) and the Schiff-base nitrogen atom (N2). Furthermore, electrostatic interactions between the terminal carboxylate and amino groups of the substrate and Arg297 and Glu81 impose substantial "strain" energy on the orientation of the cyclic intermediate to control its trajectory. In addition the "strain" energy, which appears to be sensitive to both the number of carbon atoms in the substrate/analogue and the position of the radical intermediates, may play a key role in controlling the transition of the enzyme from the closed to the open state. Our results provide new insights into several aspects of the radical mechanism in aminomutase catalysis and broaden our understanding of cofactor PLP-dependent reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Time-resolved fluorescence analysis of the mobile flavin cofactor

    Indian Academy of Sciences (India)

    Conformational heterogeneity of the FAD cofactor in -hydroxybenzoate hydroxylase (PHBH) was investigated with time-resolved polarized flavin fluorescence. For binary enzyme/substrate (analogue) complexes of wild-type PHBH and Tyr222 mutants, crystallographic studies have revealed two distinct flavin conformations ...

  2. Cofactory: Sequence-based prediction of cofactor specificity of Rossmann folds

    DEFF Research Database (Denmark)

    Geertz-Hansen, Henrik Marcus; Blom, Nikolaj; Feist, Adam

    2014-01-01

    Obtaining optimal cofactor balance to drive production is a challenge metabolically engineered microbial strains. To facilitate identification of heterologous enzymes with desirable altered cofactor requirements from native content, we have developed Cofactory, a method for prediction of enzyme...

  3. Radical fashion and radical fashion innovation

    NARCIS (Netherlands)

    Zhang, D.; Benedetto, Di A.C.

    2010-01-01

    This is a study of the related concepts of radical fashion and radical fashion innovation. Radical fashions are defined here as those that may never enter the market at all, and exist primarily on runway shows, in exhibitions and in publicity; by contrast, radical fashion innovations may be very

  4. Insight into cofactor recognition in arylamine N-acetyltransferase enzymes

    DEFF Research Database (Denmark)

    Xu, Ximing; Li de la Sierra-Gallay, Inés; Kubiak, Xavier Jean Philippe

    2015-01-01

    Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes that catalyze the acetyl-CoA-dependent acetylation of arylamines. To better understand the mode of binding of the cofactor by this family of enzymes, the structure of Mesorhizobium loti NAT1 [(RHILO)NAT1] was determined...... for Bacillus anthracis NAT1 and Homo sapiens NAT2. Therefore, in contrast to previous data, this study shows that different orthologous NATs can bind their cofactors in a similar way, suggesting that the mode of binding CoA in this family of enzymes is less diverse than previously thought. Moreover......, it supports the notion that the presence of the `mammalian/eukaryotic insertion loop' in certain NAT enzymes impacts the mode of binding CoA by imposing structural constraints....

  5. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis

    Science.gov (United States)

    Giancaspero, Teresa Anna; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina Maria; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-04-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in energetic metabolism, epigenetics, protein folding, as well as in a number of diverse regulatory processes. The problem of localisation of flavin cofactor synthesis events and in particular of the FAD synthase (EC 2.7.7.2) in HepG2 cells is addressed here by confocal microscopy in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalysed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesising activity, hFADS is able to operate as a FAD "chaperone". The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear or a mitochondrial enzyme that is lysine specific demethylase 1 (LSD1, EC 1.-.-.-) and dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4), respectively which carry out similar reactions of oxidative demethylation, assisted by tetrahydrofolate used to form 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells.

  6. Radical SAM, A Novel Protein Superfamily Linking Unresolved Steps in Familiar Biosynthetic Pathways with Radical Mechanisms: Functional Characterization Using New Analysis and Information Visualization Methods

    Energy Technology Data Exchange (ETDEWEB)

    Sofia, Heidi J.; Chen, Guang; Hetzler, Elizabeth G.; Reyes Spindola, Jorge F.; Miller, Nancy E.

    2001-03-01

    A large protein superfamily with over 500 members has been discovered and analyzed using powerful new bioinformatics and information visualization methods. Evidence exists that these proteins generate a 5?-deoxyadenosyl radical by reductive cleavage of S-adenosylmethionine (SAM) through an unusual Fe-S center. Radical SAM superfamily proteins function in DNA precursor, vitamin, cofactor, antibiotic, and herbicide biosynthesis in a collection of basic and familiar pathways. One of the members is interferon-inducible and is considered a candidate drug target for osteoporosis. The identification of this superfamily suggests that radical-based catalysis is important in a number of previously well-studied but unresolved biochemical pathways.

  7. Insights into hydrocarbon formation by nitrogenase cofactor homologs.

    Science.gov (United States)

    Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W

    2015-04-14

    The L-cluster is an all-iron homolog of nitrogenase cofactors. Driven by europium(II) diethylenetriaminepentaacetate [Eu(II)-DTPA], the isolated L-cluster is capable of ATP-independent reduction of CO and CN(-) to C1 to C4 and C1 to C6 hydrocarbons, respectively. Compared to its cofactor homologs, the L-cluster generates considerably more CH4 from the reduction of CO and CN(-), which could be explained by the presence of a "free" Fe atom that is "unmasked" by homocitrate as an additional site for methanation. Moreover, the elevated CH4 formation is accompanied by a decrease in the amount of longer hydrocarbons and/or the lengths of the hydrocarbon products, illustrating a competition between CH4 formation/release and C-C coupling/chain extension. These observations suggest the possibility of designing simpler synthetic clusters for hydrocarbon formation while establishing the L-cluster as a platform for mechanistic investigations of CO and CN(-) reduction without complications originating from the heterometal and homocitrate components. Nitrogenase is a metalloenzyme that is highly complex in structure and uniquely versatile in function. It catalyzes two reactions that parallel two important industrial processes: the reduction of nitrogen to ammonia, which parallels the Haber-Bosch process in ammonia production, and the reduction of carbon monoxide to hydrocarbons, which parallels the Fischer-Tropsch process in fuel production. Thus, the significance of nitrogenase can be appreciated from the perspective of the useful products it generates: (i) ammonia, the "fixed" nitrogen that is essential for the existence of the entire human population; and (ii) hydrocarbons, the "recycled" carbon fuel that could be used to directly address the worldwide energy shortage. This article provides initial insights into the catalytic characteristics of various nitrogenase cofactors in hydrocarbon formation. The reported assay system provides a useful tool for mechanistic

  8. Conformational control of cofactors in nature: The effect of methoxy group orientation on the electronic structure of ubisemiquinone

    Science.gov (United States)

    De Almeida, Wagner B.; O'Malley, Patrick J.

    2018-03-01

    Ubiquinone is the key electron and proton transfer agent in biology. Its mechanism involves the formation of its intermediate one-electron reduced form, the ubisemiquinone radical. This is formed in a protein-bound form which permits the semiquinone to vary its electronic and redox properties. This can be achieved by hydrogen bonding acceptance by one or both oxygen atoms or as we now propose by restricted orientations for the methoxy groups of the headgroup. We show how the orientation of the two methoxy groups of the quinone headgroup affects the electronic structure of the semiquinone form and demonstrate a large dependence of the ubisemiquinone spin density distribution on the orientation each methoxy group takes with respect to the headgroup ring plane. This is shown to significantly modify associated hyperfine couplings which in turn needs to be accounted for in interpreting experimental values in vivo. The study uncovers the key potential role the methoxy group orientation can play in controlling the electronic structure and spin density of ubisemiquinone and provides an electronic-level insight into the variation in electron affinity and redox potential of ubiquinone as a function of the methoxy orientation. Taken together with the already known influence of cofactor conformation on heme and chlorophyll electronic structure, it reveals a more widespread role for cofactor conformational control of electronic structure and associated electron transfer in biology.

  9. Refining the reaction mechanism of O2 towards its co-substrate in cofactor-free dioxygenases

    Directory of Open Access Journals (Sweden)

    Pedro J. Silva

    2016-12-01

    Full Text Available Cofactor-less oxygenases perform challenging catalytic reactions between singlet co-substrates and triplet oxygen, in spite of apparently violating the spin-conservation rule. In 1-H-3-hydroxy-4-oxoquinaldine-2,4-dioxygenase, the active site has been suggested by quantum chemical computations to fine tune triplet oxygen reactivity, allowing it to interact rapidly with its singlet substrate without the need for spin inversion, and in urate oxidase the reaction is thought to proceed through electron transfer from the deprotonated substrate to an aminoacid sidechain, which then feeds the electron to the oxygen molecule. In this work, we perform additional quantum chemical computations on these two systems to elucidate several intriguing features unaddressed by previous workers. These computations establish that in both enzymes the reaction proceeds through direct electron transfer from co-substrate to O2 followed by radical recombination, instead of minimum-energy crossing points between singlet and triplet potential energy surfaces without formal electron transfer. The active site does not affect the reactivity of oxygen directly but is crucial for the generation of the deprotonated form of the co-substrates, which have redox potentials far below those of their protonated forms and therefore may transfer electrons to oxygen without sizeable thermodynamic barriers. This mechanism seems to be shared by most cofactor-less oxidases studied so far.

  10. On the Metal Cofactor in the Tyrosinase Family

    Directory of Open Access Journals (Sweden)

    Francisco Solano

    2018-02-01

    Full Text Available The production of pigment in mammalian melanocytes requires the contribution of at least three melanogenic enzymes, tyrosinase and two other accessory enzymes called the tyrosinase-related proteins (Trp1 and Trp2, which regulate the type and amount of melanin. The last two proteins are paralogues to tyrosinase, and they appeared late in evolution by triplication of the tyrosinase gene. Tyrosinase is a copper-enzyme, and Trp2 is a zinc-enzyme. Trp1 has been more elusive, and the direct identification of its metal cofactor has never been achieved. However, due to its enzymatic activity and similarities with tyrosinase, it has been assumed as a copper-enzyme. Recently, recombinant human tyrosinase and Trp1 have been expressed in enough amounts to achieve for the first time their crystallization. Unexpectedly, it has been found that Trp1 contains a couple of Zn(II at the active site. This review discusses data about the metal cofactor of tyrosinase and Trps. It points out differences in the studied models, and it proposes some possible points accounting for the apparent discrepancies currently appearing. Moreover, some proposals about the possible flexibility of the tyrosinase family to uptake copper or zinc are discussed.

  11. Oxygen diffusion pathways in a cofactor-independent dioxygenase

    Science.gov (United States)

    Di Russo, Natali V.; Condurso, Heather L.; Li, Kunhua; Bruner, Steven D.; Roitberg, Adrian E.

    2015-01-01

    Molecular oxygen plays an important role in a wide variety of enzymatic reactions. Through recent research efforts combining computational and experimental methods a new view of O2 diffusion is emerging, where specific channels guide O2 to the active site. The focus of this work is DpgC, a cofactor-independent oxygenase. Molecular dynamics simulations, together with mutagenesis experiments and xenon-binding data, reveal that O2 reaches the active site of this enzyme using three main pathways and four different access points. These pathways connect a series of dynamic hydrophobic pockets, concentrating O2 at a specific face of the enzyme substrate. Extensive molecular dynamics simulations provide information about which pathways are more frequently used. This data is consistent with the results of kinetic measurements on mutants and is difficult to obtain using computational cavity-location methods. Taken together, our results reveal that although DpgC is rare in its ability of activating O2 in the absence of cofactors or metals, the way O2 reaches the active site is similar to that reported for other O2-using proteins: multiple access channels are available, and the architecture of the pathway network can provide regio- and stereoselectivity. Our results point to the existence of common themes in O2 access that are conserved among very different types of proteins. PMID:26508997

  12. Radical Change by Entrepreneurial Design

    National Research Council Canada - National Science Library

    Roberts, Nancy C

    1998-01-01

    .... How radical change in public policy has occurred in the past is then documented. We find examples of radical change by chance, radical change by consensus, radical change by learning, and radical change by entrepreneurial design...

  13. Zinc is the metal cofactor of Borrelia burgdorferi peptide deformylase.

    Science.gov (United States)

    Nguyen, Kiet T; Wu, Jen-Chieh; Boylan, Julie A; Gherardini, Frank C; Pei, Dehua

    2007-12-15

    Peptide deformylase (PDF, E.C. 3.5.1.88) catalyzes the removal of N-terminal formyl groups from nascent ribosome-synthesized polypeptides. PDF contains a catalytically essential divalent metal ion, which is tetrahedrally coordinated by three protein ligands (His, His, and Cys) and a water molecule. Previous studies revealed that the metal cofactor is a Fe2+ ion in Escherichia coli and many other bacterial PDFs. In this work, we found that PDFs from two iron-deficient bacteria, Borrelia burgdorferi and Lactobacillus plantarum, are stable and highly active under aerobic conditions. The native B. burgdorferi PDF (BbPDF) was purified 1200-fold and metal analysis revealed that it contains approximately 1.1 Zn2+ ion/polypeptide but no iron. Our studies suggest that PDF utilizes different metal ions in different organisms. These data have important implications in designing PDF inhibitors and should help address some of the unresolved issues regarding PDF structure and catalytic function.

  14. Cofactors in allergic reactions to food : physical exercise and alcohol are the most important

    NARCIS (Netherlands)

    Versluis, Astrid; van Os-Medendorp, Harmieke; Kruizinga, Astrid G; Blom, W Marty; Houben, Geert F; Knulst, André C

    2016-01-01

    INTRODUCTION: Involvement of cofactors, like physical exercise, alcohol consumption and use of several types of medication, are associated with more severe food allergic symptoms. However, there is limited evidence on how often cofactors play a role in food allergic reactions. The study aimed to get

  15. Application of NAD(P)H oxidase for cofactor regeneration in dehydrogenase catalyzed oxidations

    DEFF Research Database (Denmark)

    Rehn, Gustav; Pedersen, Asbjørn Toftgaard; Woodley, John

    2016-01-01

    alcohol dehydrogenases. However, their effective use requires an effective regeneration of the oxidized nicotinamide cofactor (NAD(P)+), which is critical for the economic feasibility of the process. NAD(P)H oxidase is an enzyme class of particular interest for this cofactor regeneration since it enables...

  16. Beyond the Protein Matrix : Probing Cofactor Variants in a Baeyer-Villiger Oxygenation Reaction

    NARCIS (Netherlands)

    Martinoli, Christian; Dudek, Hanna M.; Orru, Roberto; Edmondson, Dale E.; Fraaije, Marco W.; Mattevi, Andrea

    2013-01-01

    A general question in biochemistry is the interplay between the chemical properties of cofactors and the surrounding protein matrix. Here, the functions of NADP(+) and FAD are explored by investigation of a representative monooxygenase reconstituted with chemically modified cofactor analogues. Like

  17. Molybdenum-cofactor deficiency: an easily missed cause of neonatal convulsions

    NARCIS (Netherlands)

    Slot, H. M.; Overweg-Plandsoen, W. C.; Bakker, H. D.; Abeling, N. G.; Tamminga, P.; Barth, P. G.; van Gennip, A. H.

    1993-01-01

    Intractable seizures in the neonatal period may be caused by molybdenum-cofactor deficiency, an inborn error which combines the deficiencies of sulphite oxidase and xanthine dehydrogenase. The neurological symptoms of molybdenum cofactor and isolated sulphite oxidase deficiencies are identical. Two

  18. A radical approach to radical innovation

    NARCIS (Netherlands)

    D. Deichmann (Dirk); J.C.M. van den Ende (Jan)

    2014-01-01

    textabstractInnovation pays. Amazon, Apple, Facebook, Google – nearly every one of today’s most successful companies has a talent for developing radical new ideas. But how best to encourage radical initiative taking from employees, and does their previous success or failure at it play a role?

  19. Nuclear Receptor Cofactors in PPARγ-Mediated Adipogenesis and Adipocyte Energy Metabolism

    Directory of Open Access Journals (Sweden)

    Emily Powell

    2007-01-01

    Full Text Available Transcriptional cofactors are integral to the proper function and regulation of nuclear receptors. Members of the peroxisome proliferator-activated receptor (PPAR family of nuclear receptors are involved in the regulation of lipid and carbohydrate metabolism. They modulate gene transcription in response to a wide variety of ligands, a process that is mediated by transcriptional coactivators and corepressors. The mechanisms by which these cofactors mediate transcriptional regulation of nuclear receptor function are still being elucidated. The rapidly increasing array of cofactors has brought into focus the need for a clear understanding of how these cofactors interact in ligand- and cell-specific manners. This review highlights the differential effects of the assorted cofactors regulating the transcriptional action of PPARγ and summarizes the recent advances in understanding the physiological functions of corepressors and coactivators.

  20. EFFECTS OF CIGARETTE SMOKING ON ERYTHROCYTE ANTIOXIDATIVE ENZYME ACTIVITIES AND PLASMA CONCENTRATIONS OF THEIR COFACTORS

    Directory of Open Access Journals (Sweden)

    M. Zahraie

    2005-07-01

    Full Text Available Tobacco smoke contains numerous compounds, many ‎of which are oxidants and capable of producing free radical and enhancing ‎the oxidative stress. The aim of this study was to investigate the effect of cigarette smoking on the erythrocyte antioxidative enzyme activities and the plasma ‎concentration of their cofactors. ‎Sixty eight healthy men were enrolled, 32 of whom had never smoked and 36 had smoked at least 10 cigarettes per day for ‎at least one year. Hemolysate superoxide dismutase (Cu-Zn SOD, glutathione peroxidase (GSH-Px and ‎catalase (CAT activities were measured using spectrophotometer. Plasma copper, zinc and selenium concentrations were determined ‎using atomic absorption spectrophotometer. Plasma iron concentration was determined by colorimetric ‎method. We found that erythrocyte Cu-Zn SOD activity was significantly higher in tobacco smokers ‎compared with non-smokers (1294 ± 206.7 U/gHb in smokers vs. 1121.6 ± 237.8 U/gHb in non-‎smokers, P < 0.01. While plasma selenium concentration was significantly lower in tobacco ‎smokers (62.7±14.8 μg/L in smokers vs. 92.1 ± 17.5 μg/L in non-smokers, P < 0.01, there were no significant ‎differences in erythrocyte GSH-Px and CAT activities and plasma copper, zinc and iron concentrations between the two groups. ‎It seems that cigarette smoking can alter antioxidative enzymes activity and plasma concentration of some trace elements.

  1. Diversity and Functional Analysis of the FeMo-Cofactor Maturase NifB

    Directory of Open Access Journals (Sweden)

    Simon Arragain

    2017-11-01

    Full Text Available One of the main hurdles to engineer nitrogenase in a non-diazotrophic host is achieving NifB activity. NifB is an extremely unstable and oxygen sensitive protein that catalyzes a low-potential SAM-radical dependent reaction. The product of NifB activity is called NifB-co, a complex [8Fe-9S-C] cluster that serves as obligate intermediate in the biosyntheses of the active-site cofactors of all known nitrogenases. Here we study the diversity and phylogeny of naturally occurring NifB proteins, their protein architecture and the functions of the distinct NifB domains in order to understand what defines a catalytically active NifB. Focus is on NifB from the thermophile Chlorobium tepidum (two-domain architecture, the hyperthermophile Methanocaldococcus infernus (single-domain architecture and the mesophile Klebsiella oxytoca (two-domain architecture, showing in silico characterization of their nitrogen fixation (nif gene clusters, conserved NifB motifs, and functionality. C. tepidum and M. infernus NifB were able to complement an Azotobacter vinelandii (ΔnifB mutant restoring the Nif+ phenotype and thus demonstrating their functionality in vivo. In addition, purified C. tepidum NifB exhibited activity in the in vitro NifB-dependent nitrogenase reconstitution assay. Intriguingly, changing the two-domain K. oxytoca NifB to single-domain by removal of the C-terminal NifX-like extension resulted in higher in vivo nitrogenase activity, demonstrating that this domain is not required for nitrogen fixation in mesophiles.

  2. Free radical inactivation of trypsin

    International Nuclear Information System (INIS)

    Cudina, Ivana; Jovanovic, S.V.

    1988-01-01

    Reactivities of free radical oxidants, radical OH, Br2-anion radical and Cl 3 COO radical and a reductant, CO2-anion radical, with trypsin and reactive protein components were determined by pulse radiolysis of aqueous solutions at pH 7, 20 0 C. Highly reactive free radicals, radical OH, Br2-anion radical and CO2-anion radical, react with trypsin at diffusion controlled rates. Moderately reactive trichloroperoxy radical, k(Cl 3 COO radical + trypsin) preferentially oxidizes histidine residues. The efficiency of inactivation of trypsin by free radicals is inversely proportional to their reactivity. The yields of inactivation of trypsin by radical OH, Br2-anion radical and CO2-anion radical are low, G(inactivation) = 0.6-0.8, which corresponds to ∼ 10% of the initially produced radicals. In contrast, Cl 3 COO radical inactivates trypsin with ∼ 50% efficiency, i.e. G(inactivation) = 3.2. (author)

  3. Relocalization of human chromatin remodeling cofactor TIP48 in mitosis

    International Nuclear Information System (INIS)

    Sigala, Barbara; Edwards, Mina; Puri, Teena; Tsaneva, Irina R.

    2005-01-01

    TIP48 is a highly conserved eukaryotic AAA + protein which is an essential cofactor for several complexes involved in chromatin acetylation and remodeling, transcriptional and developmental regulation and nucleolar organization and trafficking. We show that TIP48 abundance in HeLa cells did not change during the cell cycle, nor did its distribution in various biochemical fractions. However, we observed distinct changes in the subcellular localization of TIP48 during M phase using immunofluorescence microscopy. Our studies demonstrate that in interphase cells TIP48 was found mainly in the nucleus and exhibited a distinct localization in the nuclear periphery. As the cells entered mitosis, TIP48 was excluded from the condensing chromosomes but showed association with the mitotic apparatus. During anaphase, some TIP48 was detected in the centrosome colocalizing with tubulin but the strongest staining appeared in the mitotic equator associated with the midzone central spindle. Accumulation of TIP48 in the midzone and the midbody was observed in late telophase and cytokinesis. This redeployment of TIP48 during anaphase and cytokinesis was independent of microtubule assembly. The relocation of endogenous TIP48 to the midzone/midbody under physiological conditions suggests a novel and distinct function for TIP48 in mitosis and possible involvement in the exit of mitosis

  4. Emissive Synthetic Cofactors: An Isomorphic, Isofunctional, and Responsive NAD+ Analogue.

    Science.gov (United States)

    Rovira, Alexander R; Fin, Andrea; Tor, Yitzhak

    2017-11-08

    The synthesis, photophysics, and biochemical utility of a fluorescent NAD + analogue based on an isothiazolo[4,3-d]pyrimidine core (N tz AD + ) are described. Enzymatic reactions, photophysically monitored in real time, show N tz AD + and N tz ADH to be substrates for yeast alcohol dehydrogenase and lactate dehydrogenase, respectively, with reaction rates comparable to that of the native cofactors. A drop in fluorescence is seen as N tz AD + is converted to N tz ADH, reflecting a complementary photophysical behavior to that of the native NAD + /NADH. N tz AD + and N tz ADH serve as substrates for NADase, which selectively cleaves the nicotinamide's glycosidic bond yielding tz ADP-ribose. N tz AD + also serves as a substrate for ribosyl transferases, including human adenosine ribosyl transferase 5 (ART5) and Cholera toxin subunit A (CTA), which hydrolyze the nicotinamide and transfer tz ADP-ribose to an arginine analogue, respectively. These reactions can be monitored by fluorescence spectroscopy, in stark contrast to the corresponding processes with the nonemissive NAD + .

  5. Cofactor requirement of HpyAV restriction endonuclease.

    Directory of Open Access Journals (Sweden)

    Siu-Hong Chan

    Full Text Available BACKGROUND: Helicobacter pylori is the etiologic agent of common gastritis and a risk factor for gastric cancer. It is also one of the richest sources of Type II restriction-modification (R-M systems in microorganisms. PRINCIPAL FINDINGS: We have cloned, expressed and purified a new restriction endonuclease HpyAV from H. pylori strain 26695. We determined the HpyAV DNA recognition sequence and cleavage site as CCTTC 6/5. In addition, we found that HpyAV has a unique metal ion requirement: its cleavage activity is higher with transition metal ions than in Mg(++. The special metal ion requirement of HpyAV can be attributed to the presence of a HNH catalytic site similar to ColE9 nuclease instead of the canonical PD-X-D/EXK catalytic site found in many other REases. Site-directed mutagenesis was carried out to verify the catalytic residues of HpyAV. Mutation of the conserved metal-binding Asn311 and His320 to alanine eliminated cleavage activity. HpyAV variant H295A displayed approximately 1% of wt activity. CONCLUSIONS/SIGNIFICANCE: Some HNH-type endonucleases have unique metal ion cofactor requirement for optimal activities. Homology modeling and site-directed mutagenesis confirmed that HpyAV is a member of the HNH nuclease family. The identification of catalytic residues in HpyAV paved the way for further engineering of the metal binding site. A survey of sequenced microbial genomes uncovered 10 putative R-M systems that show high sequence similarity to the HpyAV system, suggesting lateral transfer of a prototypic HpyAV-like R-M system among these microorganisms.

  6. Molybdenum cofactor deficiency: Identification of a patient with homozygote mutation in the MOCS3 gene

    NARCIS (Netherlands)

    Huijmans, Jan G. M.; Schot, Rachel; de Klerk, Johannis B. C.; Williams, Monique; de Coo, René F. M.; Duran, Marinus; Verheijen, Frans W.; van Slegtenhorst, Marjon; Mancini, Grazia M. S.

    2017-01-01

    We describe the clinical presentation and 17 years follow up of a boy, born to consanguineous parents and presenting with intellectual disability (ID), autism, "marfanoid" dysmorphic features, and moderate abnormalities of sulfite metabolism compatible with molybdenum cofactor deficiency, but normal

  7. Organic cofactors participated more frequently than transition metals in redox reactions of primitive proteins.

    Science.gov (United States)

    Ji, Hong-Fang; Chen, Lei; Zhang, Hong-Yu

    2008-08-01

    Protein redox reactions are one of the most basic and important biochemical actions. As amino acids are weak redox mediators, most protein redox functions are undertaken by protein cofactors, which include organic ligands and transition metal ions. Since both kinds of redox cofactors were available in the pre-protein RNA world, it is challenging to explore which one was more involved in redox processes of primitive proteins? In this paper, using an examination of the redox cofactor usage of putative ancient proteins, we infer that organic ligands participated more frequently than transition metals in redox reactions of primitive proteins, at least as protein cofactors. This is further supported by the relative abundance of amino acids in the primordial world. Supplementary material for this article can be found on the BioEssays website. (c) 2008 Wiley Periodicals, Inc.

  8. Redox cofactor engineering in industrial microorganisms: strategies, recent applications and future directions.

    Science.gov (United States)

    Liu, Jiaheng; Li, Huiling; Zhao, Guangrong; Caiyin, Qinggele; Qiao, Jianjun

    2018-05-01

    NAD and NADP, a pivotal class of cofactors, which function as essential electron donors or acceptors in all biological organisms, drive considerable catabolic and anabolic reactions. Furthermore, they play critical roles in maintaining intracellular redox homeostasis. However, many metabolic engineering efforts in industrial microorganisms towards modification or introduction of metabolic pathways, especially those involving consumption, generation or transformation of NAD/NADP, often induce fluctuations in redox state, which dramatically impede cellular metabolism, resulting in decreased growth performance and biosynthetic capacity. Here, we comprehensively review the cofactor engineering strategies for solving the problematic redox imbalance in metabolism modification, as well as their features, suitabilities and recent applications. Some representative examples of in vitro biocatalysis are also described. In addition, we briefly discuss how tools and methods from the field of synthetic biology can be applied for cofactor engineering. Finally, future directions and challenges for development of cofactor redox engineering are presented.

  9. Bleaching herbicide norflurazon inhibits phytoene desaturase by competition with the cofactors.

    Science.gov (United States)

    Breitenbach, J; Zhu, C; Sandmann, G

    2001-11-01

    Cofactor requirement was determined for the heterologous expressed phytoene desaturases from the cyanobacterium Synechococcus and the higher plant Gentiana lutea. The cyanobacterial enzyme is dependent on either NAD(P) or plastoquinone, whereas only quinones such as plastoquinone can function as a cofactor for the phytoene desaturase from G. lutea. Enzyme kinetic studies were carried out to determine a possible competition between the cofactors and the bleaching herbicide norflurazon. For the Synechococcus enzyme, competition between norflurazon and NADP, as well as plastoquinone, could be demonstrated. The K(m) values for these cofactors were 6.6 mM and 0.23 microM, respectively. Inhibition of the phytoene desaturase from G. lutea by norflurazon was also competitive with respect to plastoquinone. The K(m) values of both enzymes for plastoquinone were very close.

  10. A General Tool for Engineering the NAD/NADP Cofactor Preference of Oxidoreductases.

    Science.gov (United States)

    Cahn, Jackson K B; Werlang, Caroline A; Baumschlager, Armin; Brinkmann-Chen, Sabine; Mayo, Stephen L; Arnold, Frances H

    2017-02-17

    The ability to control enzymatic nicotinamide cofactor utilization is critical for engineering efficient metabolic pathways. However, the complex interactions that determine cofactor-binding preference render this engineering particularly challenging. Physics-based models have been insufficiently accurate and blind directed evolution methods too inefficient to be widely adopted. Building on a comprehensive survey of previous studies and our own prior engineering successes, we present a structure-guided, semirational strategy for reversing enzymatic nicotinamide cofactor specificity. This heuristic-based approach leverages the diversity and sensitivity of catalytically productive cofactor binding geometries to limit the problem to an experimentally tractable scale. We demonstrate the efficacy of this strategy by inverting the cofactor specificity of four structurally diverse NADP-dependent enzymes: glyoxylate reductase, cinnamyl alcohol dehydrogenase, xylose reductase, and iron-containing alcohol dehydrogenase. The analytical components of this approach have been fully automated and are available in the form of an easy-to-use web tool: Cofactor Specificity Reversal-Structural Analysis and Library Design (CSR-SALAD).

  11. The glmS ribozyme cofactor is a general acid-base catalyst.

    Science.gov (United States)

    Viladoms, Júlia; Fedor, Martha J

    2012-11-21

    The glmS ribozyme is the first natural self-cleaving ribozyme known to require a cofactor. The d-glucosamine-6-phosphate (GlcN6P) cofactor has been proposed to serve as a general acid, but its role in the catalytic mechanism has not been established conclusively. We surveyed GlcN6P-like molecules for their ability to support self-cleavage of the glmS ribozyme and found a strong correlation between the pH dependence of the cleavage reaction and the intrinsic acidity of the cofactors. For cofactors with low binding affinities, the contribution to rate enhancement was proportional to their intrinsic acidity. This linear free-energy relationship between cofactor efficiency and acid dissociation constants is consistent with a mechanism in which the cofactors participate directly in the reaction as general acid-base catalysts. A high value for the Brønsted coefficient (β ~ 0.7) indicates that a significant amount of proton transfer has already occurred in the transition state. The glmS ribozyme is the first self-cleaving RNA to use an exogenous acid-base catalyst.

  12. Orgasm after radical prostatectomy

    NARCIS (Netherlands)

    Koeman, M; VanDriel, MF; Schultz, WCMW; Mensink, HJA

    Objective To evaluate the ability to obtain and the quality of orgasm after radical prostatectomy, Patients and methods The orgasms experienced after undergoing radical prostatectomy were evaluated in 20 men (median age 65 years, range 56-76) using a semi-structured interview and a self-administered

  13. Physiology of free radicals

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2011-01-01

    Full Text Available Free radicals imply that every atom, molecule, ion, group of atoms, or molecules with one or several non-paired electrons in outer orbital. Among these are: nitrogenoxide (NO•, superoxide-anion-radical (O2•-, hydroxyl radical (OH•, peroxyl radical (ROO•, alcoxyl radical (RO• and hydroperoxyl radical (HO2•. However, reactive oxygen species also include components without non-paired electrons in outer orbital (so-called reactive non-radical agents, such as: singlet oxygen (1O2, peroxynitrite (ONOO-, hydrogen-peroxide (H2O2, hypochloric acid (eg. HOCl and ozone (O3. High concentrations of free radicals lead to the development of oxidative stress which is a precondition for numerous pathological effects. However, low and moderate concentrations of these matter, which occur quite normally during cell metabolic activity, play multiple significant roles in many reactions. Some of these are: regulation of signal pathways within the cell and between cells, the role of chemoattractors and leukocyte activators, the role in phagocytosis, participation in maintaining, changes in the position and shape of the cell, assisting the cell during adaption and recovery from damage (e.g.caused by physical effort, the role in normal cell growth, programmed cell death (apoptosis and cell ageing, in the synthesis of essential biological compounds and energy production, as well as the contribution to the regulation of the vascular tone, actually, tissue vascularization.

  14. Radicals in arithmetic

    NARCIS (Netherlands)

    W.J. Palenstijn (Willem Jan)

    2014-01-01

    htmlabstractLet K be a field. A radical is an element of the algebraic closure of K of which a power is contained in K. In this thesis we develop a method for determining what we call entanglement. This describes unexpected additive relations between radicals, and is encoded in an entanglement

  15. Radicals in arithmetic

    NARCIS (Netherlands)

    Palenstijn, Willem Jan

    2014-01-01

    Let K be a field. A radical is an element of the algebraic closure of K of which a power is contained in K. In this thesis we develop a method for determining what we call entanglement. This describes unexpected additive relations between radicals, and is encoded in an entanglement group. We give

  16. Muonium and muonic radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Geeson, D.; Symons, M.C.R.

    1985-01-01

    An energetic positive muon which is injected in a liquid sample of substrate molecules (S) creates an ionization track consisting of substrate cations (S + ) and electrons. Near the end of this track the muon may combine with an electron to form muonium (Mu) which is observable in inert liquids, but which reacts by addition to form a radical. Alternatively, the electron can add to S to form S - , which then combines with the muon to form the radical. Furthermore, instead of ending up in Mu or in a radical the muon may stay in a diamagnetic environment as a solvated muon, or as a muon substituting a proton in a molecule. Of interest in these schemes are the mechanisms and rates of formation of muonated radicals and in particular the rate constants for their reactions to products. Investigations are based on the observation of Mu and the radical by means of the μSR technique in transverse magnetic fields. (Auth.)

  17. Genome-scale consequences of cofactor balancing in engineered pentose utilization pathways in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Amit Ghosh

    Full Text Available Biofuels derived from lignocellulosic biomass offer promising alternative renewable energy sources for transportation fuels. Significant effort has been made to engineer Saccharomyces cerevisiae to efficiently ferment pentose sugars such as D-xylose and L-arabinose into biofuels such as ethanol through heterologous expression of the fungal D-xylose and L-arabinose pathways. However, one of the major bottlenecks in these fungal pathways is that the cofactors are not balanced, which contributes to inefficient utilization of pentose sugars. We utilized a genome-scale model of S. cerevisiae to predict the maximal achievable growth rate for cofactor balanced and imbalanced D-xylose and L-arabinose utilization pathways. Dynamic flux balance analysis (DFBA was used to simulate batch fermentation of glucose, D-xylose, and L-arabinose. The dynamic models and experimental results are in good agreement for the wild type and for the engineered D-xylose utilization pathway. Cofactor balancing the engineered D-xylose and L-arabinose utilization pathways simulated an increase in ethanol batch production of 24.7% while simultaneously reducing the predicted substrate utilization time by 70%. Furthermore, the effects of cofactor balancing the engineered pentose utilization pathways were evaluated throughout the genome-scale metabolic network. This work not only provides new insights to the global network effects of cofactor balancing but also provides useful guidelines for engineering a recombinant yeast strain with cofactor balanced engineered pathways that efficiently co-utilizes pentose and hexose sugars for biofuels production. Experimental switching of cofactor usage in enzymes has been demonstrated, but is a time-consuming effort. Therefore, systems biology models that can predict the likely outcome of such strain engineering efforts are highly useful for motivating which efforts are likely to be worth the significant time investment.

  18. Salvage robotic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Samuel D Kaffenberger

    2014-01-01

    Full Text Available Failure of non-surgical primary treatment for localized prostate cancer is a common occurrence, with rates of disease recurrence ranging from 20% to 60%. In a large proportion of patients, disease recurrence is clinically localized and therefore potentially curable. Unfortunately, due to the complex and potentially morbid nature of salvage treatment, radical salvage surgery is uncommonly performed. In an attempt to decrease the morbidity of salvage therapy without sacrificing oncologic efficacy, a number of experienced centers have utilized robotic assistance to perform minimally invasive salvage radical prostatectomy. Herein, we critically evaluate the existing literature on salvage robotic radical prostatectomy with a focus on patient selection, perioperative complications and functional and early oncologic outcomes. These results are compared with contemporary and historical open salvage radical prostatectomy series and supplemented with insights we have gained from our experience with salvage robotic radical prostatectomy. The body of evidence by which conclusions regarding the efficacy and safety of robotic salvage radical prostatectomy can be drawn comprises fewer than 200 patients with limited follow-up. Preliminary results are promising and some outcomes have been favorable when compared with contemporary open salvage prostatectomy series. Advantages of the robotic platform in the performance of salvage radical prostatectomy include decreased blood loss, short length of stay and improved visualization. Greater experience is required to confirm the long-term oncologic efficacy and functional outcomes as well as the generalizability of results achieved at experienced centers.

  19. Investigation of the cofactor controlled substrate specificity of yeast inorganic pyrophosphatase

    International Nuclear Information System (INIS)

    Dunaway-Mariano, D.; Barry, R.J.; Brush, T.; Ting, S.J.

    1986-01-01

    The PPase reaction requires the participation of three metal ion cofactors. One metal ion binds to PP activating it for reaction and the other two bind to the enzyme activating it for catalysis. Of the metal ions tested only Mg 2+ , Zn 2+ , Co 2+ , Mn 2+ can perform all these roles. Most trivalent metal ions can function to activate the PP for reaction but cannot activate the enzyme for catalysis. The Mg 2+ activated enzyme is specific for M-PP and M-PPS complexes while the Zn 2+ activated enzyme also acts on metal complexes of PPP, PPPOR, PPOR and PPF. 18 O-Incorporation studies show that the substituted phosphoryl group of the unsymmetrical PP complexes always serves as the leaving group. To gain insight into the mechanism of the cofactor control over the substrate specificity the order of substrate/cofactor binding to the enzyme was examined. Dead end inhibition studies in which Cr(III)PP served as substrate and Mg 2+ as cofactor indicate that the mechanism is rapid equilibrium ordered (CrPP binds first) while dead end inhibitor induced activator inhibition studies with Mg 2+ and MgPP indicate that the kinetic mechanism is steady state preferred order. Cofactor-enzyme binding was studied as a function of substrate structure and the results obtained rule out interference of Mg 2+ binding by substrate analogs as an explanation for the different substrate specificities of the Zn 2+ and Mg 2+ activated enzymes

  20. Expression and localization of tubulin cofactors TBCD and TBCE in human gametes.

    Science.gov (United States)

    Jiménez-Moreno, Victoria; Agirregoitia, Ekaitz

    2017-06-01

    The tubulin cofactors TBCD and TBCE play an essential role in regulation of the microtubule dynamics in a wide variety of somatic cells, but little information is known about the expression of these cofactors in human sperm and oocytes. In this study, we focused on the investigation of the presence of, and the differential distribution of, the tubulin cofactors TBCD and TBCE in human sperm and during human oocyte maturation. We performed expression assays for TBCD and TBCE by reverse transcription-polymerase chain reaction (RT-PCR), western blot and immunofluorescence and verified the presence of both cofactors in human gametes. TBCD and TBCE were located mainly in the middle region and in the tail of the sperm while in the oocyte the localization was cytosolic. The mRNA of both tubulin cofactors were present in the human oocytes but not in sperm cells. This finding gives a first insight into where TBCD and TBCE could carry out their function in the continuous changes that the cytoskeleton experiences during gametogenesis and also prior to fertilization.

  1. Gnosticism and Radical Feminism

    DEFF Research Database (Denmark)

    Cahana, Jonathan

    2016-01-01

    and radical feminism would easily fall under this definition. There is, however, one major difference: since radical feminism is a relatively recent phenomenon which also benefited from modern modes of text production and preservation, almost all of the sources are still with us. This, in turn, may allow us...... to use radical feminism to make certain aspects of ancient Gnosticism re-emerge from their long submersion, provided that enough similarities can be independently drawn between the two phenomena to merit such a comparison. This paper therefore presents a comparison between concepts and positions...

  2. Homegrown religious radicalization

    DEFF Research Database (Denmark)

    Khawaja, Iram

    It has been reported that a growing number of youngsters from Western Europe are engaging in conflicts motivated by religious and political conflicts in the Middle East. This paper explores the reasons behind this seemingly religious radicalization from the point of view of the youngsters...... youngsters and parents of youngsters who have chosen a radicalized path in life. The paper will shed light on how the sense of and yearning for belonging and recognition have to be taken into account in our understanding of homegrown religious radicalization...

  3. Radical chemistry of artemisinin

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2011-12-29

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  4. Radical chemistry of artemisinin

    Science.gov (United States)

    Denisov, Evgenii T.; Solodova, S. L.; Denisova, Taisa G.

    2010-12-01

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  5. Radical chemistry of artemisinin

    International Nuclear Information System (INIS)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G

    2010-01-01

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  6. Radical's view of sciences

    International Nuclear Information System (INIS)

    Mittal, J.P.

    2004-01-01

    Full text: General concept in radiation biology is that free radicals are highly reactive and they can damage vital cellular molecules leading to injurious effects. However, in this talk, evidence will be presented through the techniques of electron paramagnetic resonance ( EPR ) and pulse radiolysis that free radicals can be highly selective in their reaction with the target molecules. In addition, attempts will be made to present a brief account of emerging scenario of free radical generation, identification and their involvement in radiation damage mechanisms in chemical and biological systems

  7. Radical chemistry of artemisinin

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2010-12-29

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  8. Moderate and Radical Islam

    National Research Council Canada - National Science Library

    Rabasa, Angel

    2005-01-01

    This report presents the statement of Angel Rabasa, PhD, Senior Policy Analyst, The RAND Corporation, to the Committee on Armed Services, Defense Review Terrorism and Radical Islam Gap Panel, United...

  9. [On the influence of local molecular environment on the redox potential of electron transfer cofactors in bacterial photosynthetic reaction centers].

    Science.gov (United States)

    Krasil'nikov, P M; Noks, P P; Rubin, A B

    2011-01-01

    The addition of cryosolvents (glycerol, dimethylsulfoxide) to a water solution containing bacterial photosynthetic reaction centers changes the redox potential of the bacteriochlorophyll dimer, but does not affect the redox potential of the quinone primary acceptor. It has been shown that the change in redox potential can be produced by changes of the electrostatic interactions between cofactors and the local molecular environment modified by additives entered into the solution. The degree of influence of a solvent on the redox potential of various cofactors is determined by degree of availability of these cofactors for molecules of solvent, which depends on the arrangement of cofactors in the structure of reaction centers.

  10. Separation of xylose and glucose using an integrated membrane system for enzymatic cofactor regeneration and downstream purification

    DEFF Research Database (Denmark)

    Morthensen, Sofie Thage; Sigurdardóttir, Sigyn Björk; Meyer, Anne S.

    2017-01-01

    Mixtures of xylose, glucose and pyruvate were fed to a membrane bioreactor equipped with a charged NF membrane (NTR 7450). Value-added products were obtained in the reactor via enzymatic cofactor-dependent catalysis of glucose to gluconic acid and pyruvate to lactic acid, respectively. The initial...... cofactor (NADH) concentration could be decreased to 10% of the stoichiometric value (relative to glucose) without compromising process time and substrate conversion via i) efficient cofactor regeneration and ii) high retention of cofactor (R=0.98) in the membrane bioreactor. Furthermore, accumulation...

  11. Cytosolic iron chaperones: Proteins delivering iron cofactors in the cytosol of mammalian cells.

    Science.gov (United States)

    Philpott, Caroline C; Ryu, Moon-Suhn; Frey, Avery; Patel, Sarju

    2017-08-04

    Eukaryotic cells contain hundreds of metalloproteins that are supported by intracellular systems coordinating the uptake and distribution of metal cofactors. Iron cofactors include heme, iron-sulfur clusters, and simple iron ions. Poly(rC)-binding proteins are multifunctional adaptors that serve as iron ion chaperones in the cytosolic/nuclear compartment, binding iron at import and delivering it to enzymes, for storage (ferritin) and export (ferroportin). Ferritin iron is mobilized by autophagy through the cargo receptor, nuclear co-activator 4. The monothiol glutaredoxin Glrx3 and BolA2 function as a [2Fe-2S] chaperone complex. These proteins form a core system of cytosolic iron cofactor chaperones in mammalian cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Synthesis, delivery and regulation of eukaryotic heme and Fe-S cluster cofactors.

    Science.gov (United States)

    Barupala, Dulmini P; Dzul, Stephen P; Riggs-Gelasco, Pamela Jo; Stemmler, Timothy L

    2016-02-15

    In humans, the bulk of iron in the body (over 75%) is directed towards heme- or Fe-S cluster cofactor synthesis, and the complex, highly regulated pathways in place to accomplish biosynthesis have evolved to safely assemble and load these cofactors into apoprotein partners. In eukaryotes, heme biosynthesis is both initiated and finalized within the mitochondria, while cellular Fe-S cluster assembly is controlled by correlated pathways both within the mitochondria and within the cytosol. Iron plays a vital role in a wide array of metabolic processes and defects in iron cofactor assembly leads to human diseases. This review describes progress towards our molecular-level understanding of cellular heme and Fe-S cluster biosynthesis, focusing on the regulation and mechanistic details that are essential for understanding human disorders related to the breakdown in these essential pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Chemomimetic biocatalysis: exploiting the synthetic potential of cofactor-dependent enzymes to create new catalysts.

    Science.gov (United States)

    Prier, Christopher K; Arnold, Frances H

    2015-11-11

    Despite the astonishing breadth of enzymes in nature, no enzymes are known for many of the valuable catalytic transformations discovered by chemists. Recent work in enzyme design and evolution, however, gives us good reason to think that this will change. We describe a chemomimetic biocatalysis approach that draws from small-molecule catalysis and synthetic chemistry, enzymology, and molecular evolution to discover or create enzymes with non-natural reactivities. We illustrate how cofactor-dependent enzymes can be exploited to promote reactions first established with related chemical catalysts. The cofactors can be biological, or they can be non-biological to further expand catalytic possibilities. The ability of enzymes to amplify and precisely control the reactivity of their cofactors together with the ability to optimize non-natural reactivity by directed evolution promises to yield exceptional catalysts for challenging transformations that have no biological counterparts.

  14. Violent Radicalization in Europe

    DEFF Research Database (Denmark)

    Dalgaard-Nielsen, Anja

    2010-01-01

    When, why, and how do people living in a democracy become radicalized to the point of being willing to use or directly support the use of terrorist violence against fellow citizens? This question has been at the center of academic and public debate over the past years as terrorist attacks...... within this field and to answer the question: From an empirical point of view, what is known and what is not known about radicalization connected to militant Islamism in Europe?...

  15. Co-factors necessary for PPAR mediated transactivation of endogenous target genes

    DEFF Research Database (Denmark)

    Grøntved, Lars; Nielsen, Ronni; Stunnenberg, Henk

    of endogenous target gene in different cell types are elusive. To mutually compare the ability of the PPAR subtypes to activate endogenous target genes in a given cell, PPARa, PPARb/d and PPARg2 were HA tagged and rapidly, equally and synchronously expressed using adenoviral delivery. Within a few hours after...... subtype specific activation of target genes. Accumulating evidence suggests that transcriptional co-factors can function as master regulators for nuclear receptors and impose promoter selectivity. To study co-factor necessity for PPAR mediated transactivation of endogenous target genes, specific co...

  16. Laparoscopic radical trachelectomy.

    Science.gov (United States)

    Rendón, Gabriel J; Ramirez, Pedro T; Frumovitz, Michael; Schmeler, Kathleen M; Pareja, Rene

    2012-01-01

    The standard treatment for patients with early-stage cervical cancer has been radical hysterectomy. However, for women interested in future fertility, radical trachelectomy is now considered a safe and feasible option. The use of minimally invasive surgical techniques to perform this procedure has recently been reported. We report the first case of a laparoscopic radical trachelectomy performed in a developing country. The patient is a nulligravid, 30-y-old female with stage IB1 adenocarcinoma of the cervix who desired future fertility. She underwent a laparoscopic radical trachelectomy and bilateral pelvic lymph node dissection. The operative time was 340 min, and the estimated blood loss was 100mL. There were no intraoperative or postoperative complications. The final pathology showed no evidence of residual disease, and all pelvic lymph nodes were negative. At 20 mo of follow-up, the patient is having regular menses but has not yet attempted to become pregnant. There is no evidence of recurrence. Laparoscopic radical trachelectomy with pelvic lymphadenectomy in a young woman who desires future fertility may also be an alternative technique in the treatment of early cervical cancer in developing countries.

  17. Switching an O2 sensitive glucose oxidase bioelectrode into an almost insensitive one by cofactor redesign.

    Science.gov (United States)

    Tremey, Emilie; Suraniti, Emmanuel; Courjean, Olivier; Gounel, Sébastien; Stines-Chaumeil, Claire; Louerat, Frédéric; Mano, Nicolas

    2014-06-04

    In the 5-8 mM glucose concentration range, of particular interest for diabetes management, glucose oxidase bioelectrodes are O2 dependent, which decrease their efficiencies. By replacing the natural cofactor of glucose oxidase, we succeeded in turning an O2 sensitive bioelectrode into an almost insensitive one.

  18. Engineering cofactor flexibility enhanced 2,3-butanediol production in Escherichia coli.

    Science.gov (United States)

    Liang, Keming; Shen, Claire R

    2017-12-01

    Enzymatic reduction of acetoin into 2,3-butanediol (2,3-BD) typically requires the reduced nicotinamide adenine dinucleotide (NADH) or its phosphate form (NADPH) as electron donor. Efficiency of 2,3-BD biosynthesis, therefore, is heavily influenced by the enzyme specificity and the cofactor availability which varies dynamically. This work describes the engineering of cofactor flexibility for 2,3-BD production by simultaneous overexpression of an NADH-dependent 2,3-BD dehydrogenase from Klebsiella pneumoniae (KpBudC) and an NADPH-specific 2,3-BD dehydrogenase from Clostridium beijerinckii (CbAdh). Co-expression of KpBudC and CbAdh not only enabled condition versatility for 2,3-BD synthesis via flexible utilization of cofactors, but also improved production stereo-specificity of 2,3-BD without accumulation of acetoin. With optimization of medium and fermentation condition, the co-expression strain produced 92 g/L of 2,3-BD in 56 h with 90% stereo-purity for (R,R)-isoform and 85% of maximum theoretical yield. Incorporating cofactor flexibility into the design principle should benefit production of bio-based chemical involving redox reactions.

  19. Reorientational properties of fluorescent analogues of the protein kinase C cofactors diacylglycerol and phorbol ester.

    NARCIS (Netherlands)

    Pap, E.H.W.; Ketelaars, M.; Borst, J.W.; Hoek, van A.; Visser, A.J.W.G.

    1996-01-01

    The reorientational properties of the fluorescently labelled protein kinase C (PKC) cofactors diacylglycerol (DG) and phorbol ester (PMA) in vesicles and mixed micelles have been investigated using time-resolved polarised fluorescence. The sn-2 acyl chain of DG was replaced by diphenylhexatriene-

  20. RNAi-Based Identification of Gene-Specific Nuclear Cofactor Networks Regulating Interleukin-1 Target Genes

    Directory of Open Access Journals (Sweden)

    Johanna Meier-Soelch

    2018-04-01

    Full Text Available The potent proinflammatory cytokine interleukin (IL-1 triggers gene expression through the NF-κB signaling pathway. Here, we investigated the cofactor requirements of strongly regulated IL-1 target genes whose expression is impaired in p65 NF-κB-deficient murine embryonic fibroblasts. By two independent small-hairpin (shRNA screens, we examined 170 genes annotated to encode nuclear cofactors for their role in Cxcl2 mRNA expression and identified 22 factors that modulated basal or IL-1-inducible Cxcl2 levels. The functions of 16 of these factors were validated for Cxcl2 and further analyzed for their role in regulation of 10 additional IL-1 target genes by RT-qPCR. These data reveal that each inducible gene has its own (quantitative requirement of cofactors to maintain basal levels and to respond to IL-1. Twelve factors (Epc1, H2afz, Kdm2b, Kdm6a, Mbd3, Mta2, Phf21a, Ruvbl1, Sin3b, Suv420h1, Taf1, and Ube3a have not been previously implicated in inflammatory cytokine functions. Bioinformatics analysis indicates that they are components of complex nuclear protein networks that regulate chromatin functions and gene transcription. Collectively, these data suggest that downstream from the essential NF-κB signal each cytokine-inducible target gene has further subtle requirements for individual sets of nuclear cofactors that shape its transcriptional activation profile.

  1. Separation of photo-induced radical pair in cryptochrome to a functionally critical distance

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Domratcheva, Tatiana; Schulten, Klaus

    2014-01-01

    Cryptochrome is a blue light receptor that acts as a sensor for the geomagnetic field and assists many animals in long-range navigation. The magnetoreceptor function arises from light-induced formation of a radical pair through electron transfer between a flavin cofactor (FAD) and a triad...... of tryptophan residues. Here, this electron transfer is investigated by quantum chemical and classical molecular dynamics calculations. The results reveal how sequential electron transfer, assisted by rearrangement of polar side groups in the cryptochrome interior, can yield a FAD-Trp radical pair state...... step can overcome in speed both recombination (electron back-transfer) and proton transfer involving the radical pair reached after primary electron transfer....

  2. Radical dematerialization and degrowth

    Science.gov (United States)

    Kallis, Giorgos

    2017-05-01

    The emission targets agreed in Paris require a radical reduction of material extraction, use and disposal. The core claim of this article is that a radical dematerialization can only be part and parcel of degrowth. Given that capitalist economies are designed to grow, this raises the question of whether, and under what circumstances, the inevitable `degrowth' can become socially sustainable. Three economic policies are discussed in this direction: work-sharing, green taxes and public money. This article is part of the themed issue 'Material demand reduction'.

  3. Muon substituted free radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Gygax, F.N.; Brinkman, G.A.; Louwrier, P.W.F.; McKenna, D.; Ramos, M.; Webster, B.C.

    1984-01-01

    Spin polarized energetic positive muons are injected as magnetic probes into unsaturated organic liquids. They are implemented via fast chemical processes ( -10 s) in various molecules. Of particular interest among these are muonium substituted free radicals. The technique allows determination of accurate rate coefficients for fast chemical reactions of radicals. Furthermore, radiochemical processes occuring in picoseconds after injection of the muon are studied. Of fundamental interest are also the structural and dynamical implications of substituting a proton by a muon, or in other terms, a hydrogen atom by a muonium atom. Selected examples for each of these three types of experiments are given. (Auth.)

  4. Proteolytic cleavage orchestrates cofactor insertion and protein assembly in [NiFe]-hydrogenase biosynthesis.

    Science.gov (United States)

    Senger, Moritz; Stripp, Sven T; Soboh, Basem

    2017-07-14

    Metalloenzymes catalyze complex and essential processes, such as photosynthesis, respiration, and nitrogen fixation. For example, bacteria and archaea use [NiFe]-hydrogenases to catalyze the uptake and release of molecular hydrogen (H 2 ). [NiFe]-hydrogenases are redox enzymes composed of a large subunit that harbors a NiFe(CN) 2 CO metallo-center and a small subunit with three iron-sulfur clusters. The large subunit is synthesized with a C-terminal extension, cleaved off by a specific endopeptidase during maturation. The exact role of the C-terminal extension has remained elusive; however, cleavage takes place exclusively after assembly of the [NiFe]-cofactor and before large and small subunits form the catalytically active heterodimer. To unravel the functional role of the C-terminal extension, we used an enzymatic in vitro maturation assay that allows synthesizing functional [NiFe]-hydrogenase-2 of Escherichia coli from purified components. The maturation process included formation and insertion of the NiFe(CN) 2 CO cofactor into the large subunit, endoproteolytic cleavage of the C-terminal extension, and dimerization with the small subunit. Biochemical and spectroscopic analysis indicated that the C-terminal extension of the large subunit is essential for recognition by the maturation machinery. Only upon completion of cofactor insertion was removal of the C-terminal extension observed. Our results indicate that endoproteolytic cleavage is a central checkpoint in the maturation process. Here, cleavage temporally orchestrates cofactor insertion and protein assembly and ensures that only cofactor-containing protein can continue along the assembly line toward functional [NiFe]-hydrogenase. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Counter radicalization development assistance

    OpenAIRE

    van Hippel, Karin

    2006-01-01

    The paper reviews current research and practice and recommends strategies for development agencies working in the Arab and Muslim world. It builds on the basic assumption that the realization of the Millennium Development Goals will be vital to reduce support for terrorism in the long term. Within this overall framework, emphasis is placed on particular programs that could be specifically applied to counter radicalization.

  6. Radically enhanced molecular recognition

    KAUST Repository

    Trabolsi, Ali; Khashab, Niveen M.; Fahrenbach, Albert C.; Friedman, Douglas C.; Colvin, Michael T.; Coti, Karla K.; Bení tez, Diego S.; Tkatchouk, Ekaterina; Olsen, John Carl; Belowich, Matthew E.; Carmieli, Raanan; Khatib, Hussam A.; Goddard, William Andrew III; Wasielewski, Michael R.; Stoddart, Fraser Fraser Raser

    2009-01-01

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.

  7. Sexuality Following Radical Prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Serefoglu, Ege C; Albersen, Maarten

    2017-01-01

    incontinence in relation to sexual activity after surgery. This can present at the time of orgasm (ie, climacturia) or arise during arousal. In general, the problem subsides with time and pelvic floor training and tension penile loops can be used as treatments. Orgasmic disturbances after radical prostatectomy...

  8. Radically enhanced molecular recognition

    KAUST Repository

    Trabolsi, Ali

    2009-12-17

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.

  9. Online Radicalization: Bangladesh Perspective

    Science.gov (United States)

    2017-06-09

    radicalization through cyberspace, Bangladesh mostly implements hard powers such as removing contents and restricting access to the internet. However, freedom...cyberspace, Bangladesh mostly implements hard powers such as removing contents and restricting access to the internet. However, freedom of speech...67 An Organizational Approach to Implement the Measures........................................ 69 Formation of

  10. Cation radicals of xanthophylls.

    Science.gov (United States)

    Galinato, Mary Grace I; Niedzwiedzki, Dariusz; Deal, Cailin; Birge, Robert R; Frank, Harry A

    2007-10-01

    Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment-protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene, and lycopene were generated in solution using ferric chloride as an oxidant and then studied by absorption spectroscopy. The investigation provides a view toward understanding the molecular features that determine the spectral properties of cation radicals of carotenoids. The absorption spectral data reveal a shift to longer wavelength with increasing pi-chain length. However, zeaxanthin and beta-cryptoxanthin exhibit cation radical spectra blue-shifted compared to that of beta-carotene, despite all of these molecules having 11 conjugated carbon-carbon double bonds. CIS molecular orbital theory quantum computations interpret this effect as due to the hydroxyl groups in the terminal rings selectively stabilizing the highest occupied molecular orbitals of preferentially populated s-trans-isomers. The data are expected to be useful in the analysis of spectral results from PSII pigment-protein complexes seeking to understand the role of carotene and xanthophyll cation radicals in regulating excited state energy flow, in protecting PSII reaction centers against photoinhibition, and in dissipating excess light energy absorbed by photosynthetic organisms but not used for photosynthesis.

  11. Free radical transfer in polymers

    International Nuclear Information System (INIS)

    Sonntag, C. von; Bothe, E.; Ulanski, P.

    1998-01-01

    For the present study of free-radical transfer in polymers pulse radiolysis and product studies have been carried out in aqueous solutions using thus far only the water-soluble polymers polyacrylic acid, polymethacrylic acid and polyvinyl alcohol. When OH radicals, generated in the radiolysis of N 2 O-saturated aqueous solutions, react with polymers the lifetime of the polymer radical thus created very much depends on the number of radicals per polymer chain. When there are a large number of radicals per chain their bimolecular decay may be faster than the corresponding (diffusion controlled) decay of monomeric radicals, but when the macromolecule contains only few or even just one radical their lifetime is considerably prolonged. Highly charged polymers such as polyacrylic acid at high pH attain a rod-like conformation which again favors a long lifetime of the radicals. Under such conditions, radical transfer reactions can occur. For example, in polyacrylic acid OH radicals generate two kinds of radicals side by side. The radical in β-position to the carboxylate group converts into the thermodynamically more stable α-radicals by an H-transfer reaction as can be followed by spectrophotometry. Besides radical transfer reactions β-fragmentation reactions occur causing chain scission. Such reactions can be followed in a pulse radiolysis experiment by conductometry, because counter ions are released upon chain scission. Such a process is especially effective in the case of polymethacrylic acid, where it results in a chain depolymerization. An intramolecular H-abstraction is also observed in the γ-radiolysis of polyacrylic acid with the corresponding peroxyl radicals. This causes a chain reaction to occur. The resulting hydroperoxides are unstable and decarboxylate given rise to acetylacetone-like products. In polyvinyl alcohol the peroxyl radicals in α-position to the alcohol function undergo HO 2 -elimination. This prevents a scission of the polymer chain in the

  12. Muonium-containing vinyl radicals

    International Nuclear Information System (INIS)

    Rhodes, C.J.; Symons, M.C.R.; Roduner, E.; Heming, M.

    1987-01-01

    Exposure of trimethylsilylacetylene and bis(trimethylsilyl)acetylene to positive muons gave radicals whose muon-electron hyperfine coupling constants establish that the corresponding vinyl radicals were formed. (author)

  13. Optimal cofactor swapping can increase the theoretical yield for chemical production in Escherichia coli and Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    King, Zachary A.; Feist, Adam

    2014-01-01

    Maintaining cofactor balance is a critical function in microorganisms, but often the native cofactor balance does not match the needs of an engineered metabolic flux state. Here, an optimization procedure is utilized to identify optimal cofactor-specificity "swaps" for oxidoreductase enzymes...... specificity of central metabolic enzymes (especially GAPD and ALCD2x) is shown to increase NADPH production and increase theoretical yields for native products in E. coli and yeast-including l-aspartate, l-lysine, l-isoleucine, l-proline, l-serine, and putrescine-and non-native products in E. coli-including 1...

  14. DEAH-RHA helicase•Znf cofactor systems in kinetoplastid RNA editing and evolutionarily distant RNA processes

    Science.gov (United States)

    Cruz-Reyes, Jorge; Mooers, Blaine H.M.; Abu-Adas, Zakaria; Kumar, Vikas; Gulati, Shelly

    2016-01-01

    Multi-zinc finger proteins are an emerging class of cofactors in DEAH-RHA RNA helicases across highly divergent eukaryotic lineages. DEAH-RHA helicase•zinc finger cofactor partnerships predate the split of kinetoplastid protozoa, which include several human pathogens, from other eukaryotic lineages 100–400 Ma. Despite a long evolutionary history, the prototypical DEAH-RHA domains remain highly conserved. This short review focuses on a recently identified DEAH-RHA helicase•zinc finger cofactor system in kinetoplastid RNA editing, and its potential functional parallels with analogous systems in embryogenesis control in nematodes and antivirus protection in humans. PMID:27540585

  15. Solution Structure of LXXLL-related Cofactor Peptide of Orphan Nuclear Receptor FTZ-F1

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Ji Hye; Lee, Chul Jin; Jung, Jin Won; Lee, Weon Tae [Yonsei University, Seoul (Korea, Republic of)

    2012-02-15

    Functional interaction between Drosophila orphan receptor FTZ-F1 (NR5A3) and a segmentation gene product fushi tarazu (FTZ) is crucial for regulating genes related to define the identities of alternate segmental regions in the Drosophila embryo. FTZ binding to the ligand-binding domain (LBD) of FTZ-F1 is of essence in activating its transcription process. We determined solution structures of the cofactor peptide (FTZ{sup PEP}) derived from FTZ by NMR spectroscopy. The cofactor peptide showed a nascent helical conformation in aqueous solution, however, the helicity was increased in the presence of TFE. Furthermore, FTZ{sup PEP} formed α- helical conformation upon FTZ-F1 binding, which provides a receptor bound structure of FTZ{sup PEP}. The solution structure of FTZ{sup PEP} in the presence of FTZ-F1 displays a long stretch of the α-helix with a bend in the middle of helix.

  16. Kinetics based reaction optimization of enzyme catalysed reduction of formaldehyde to methanol with synchronous cofactor regeneration

    DEFF Research Database (Denmark)

    Marpani, Fauziah Binti; Sárossy, Zsuzsa; Pinelo, Manuel

    2017-01-01

    regeneration of the reducing equivalents during reaction is required. Herein, we report the optimization of the enzymatic conversion of formaldehyde (CHOH) to CH3 OH by alcohol dehydrogenase, the final step of the enzymatic redox reaction of CO2 to CH3 OH, with kinetically synchronous enzymatic cofactor...... regeneration using either glucose dehydrogenase (System I) or xylose dehydrogenase (System II). A mathematical model of the enzyme kinetics was employed to identify the best reaction set-up for attaining optimal cofactor recycling rate and enzyme utilization efficiency. Targeted process optimization...... experiments were conducted to verify the kinetically modelled results. Repetitive reaction cycles were shown to enhance the yield of CH3 OH, increase the total turnover number (TTN) and the biocatalytic productivity rate (BPR) value for both system I and II whilst minimizing the exposure of the enzymes...

  17. Solution Structure of LXXLL-related Cofactor Peptide of Orphan Nuclear Receptor FTZ-F1

    International Nuclear Information System (INIS)

    Yun, Ji Hye; Lee, Chul Jin; Jung, Jin Won; Lee, Weon Tae

    2012-01-01

    Functional interaction between Drosophila orphan receptor FTZ-F1 (NR5A3) and a segmentation gene product fushi tarazu (FTZ) is crucial for regulating genes related to define the identities of alternate segmental regions in the Drosophila embryo. FTZ binding to the ligand-binding domain (LBD) of FTZ-F1 is of essence in activating its transcription process. We determined solution structures of the cofactor peptide (FTZ PEP ) derived from FTZ by NMR spectroscopy. The cofactor peptide showed a nascent helical conformation in aqueous solution, however, the helicity was increased in the presence of TFE. Furthermore, FTZ PEP formed α- helical conformation upon FTZ-F1 binding, which provides a receptor bound structure of FTZ PEP . The solution structure of FTZ PEP in the presence of FTZ-F1 displays a long stretch of the α-helix with a bend in the middle of helix

  18. A toxic imbalance of Hsp70s in Saccharomyces cerevisiae is caused by competition for cofactors.

    Science.gov (United States)

    Keefer, Kathryn M; True, Heather L

    2017-09-01

    Molecular chaperones are responsible for managing protein folding from translation through degradation. These crucial machines ensure that protein homeostasis is optimally maintained for cell health. However, 'too much of a good thing' can be deadly, and the excess of chaperones can be toxic under certain cellular conditions. For example, overexpression of Ssa1, a yeast Hsp70, is toxic to cells in folding-challenged states such as [PSI+]. We discovered that overexpression of the nucleotide exchange factor Sse1 can partially alleviate this toxicity. We further argue that the basis of the toxicity is related to the availability of Hsp70 cofactors, such as Hsp40 J-proteins and nucleotide exchange factors. Ultimately, our work informs future studies about functional chaperone balance and cautions against therapeutic chaperone modifications without a thorough examination of cofactor relationships. © 2017 John Wiley & Sons Ltd.

  19. Crystallization and preliminary X-ray analysis of tubulin-folding cofactor A from Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Lu, Lu; Nan, Jie; Mi, Wei; Wei, Chun-Hong; Li, Lan-Fen; Li, Yi

    2010-01-01

    Tubulin-folding cofactor A from A. thaliana has been crystallized and preliminarily analyzed using X-ray diffraction. Tubulin-folding cofactor A (TFC A) is a molecular post-chaperonin that is involved in the β-tubulin-folding pathway. It has been identified in many organisms including yeasts, humans and plants. In this work, Arabidopsis thaliana TFC A was expressed in Escherichia coli and purified to homogeneity. After thrombin cleavage, a well diffracting crystal was obtained by the sitting-drop vapour-diffusion method at 289 K. The crystal diffracted to 1.6 Å resolution using synchrotron radiation and belonged to space group I4 1 , with unit-cell parameters a = 55.0, b = 55.0, c = 67.4 Å

  20. Probing the structural basis of oxygen binding in a cofactor-independent dioxygenase.

    Science.gov (United States)

    Li, Kunhua; Fielding, Elisha N; Condurso, Heather L; Bruner, Steven D

    2017-07-01

    The enzyme DpgC is included in the small family of cofactor-independent dioxygenases. The chemistry of DpgC is uncommon as the protein binds and utilizes dioxygen without the aid of a metal or organic cofactor. Previous structural and biochemical studies identified the substrate-binding mode and the components of the active site that are important in the catalytic mechanism. In addition, the results delineated a putative binding pocket and migration pathway for the co-substrate dioxygen. Here, structural biology is utilized, along with site-directed mutagenesis, to probe the assigned dioxygen-binding pocket. The key residues implicated in dioxygen trafficking were studied to probe the process of binding, activation and chemistry. The results support the proposed chemistry and provide insight into the general mechanism of dioxygen binding and activation.

  1. Free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E.; Wasley, Richard J.

    1979-01-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a getter additive comprising a compound or mixture of compounds capable of capturing or deactivating free radicals or ions under mechanical or electrical shock conditions and which is not an explosive. Exemplary getter additives are isocyanates, olefins and iodine.

  2. Trends in radical prostatectomy.

    Science.gov (United States)

    Eastham, James; Tokuda, Yuji; Scardino, Peter

    2009-02-01

    The surgical treatment of prostate cancer ideally removes the entire cancer, avoids excessive blood loss or serious perioperative complications, and results in complete recovery of continence and potency. To achieve this, the surgeon must excise sufficient periprostatic tissue to cure the cancer while preserving the cavernosal nerves required for erectile function and the neuromusculature required for normal urinary and bowel function. Here we will examine recent trends in radical prostatectomy, focusing on surgical technique.

  3. Kinetics based reaction optimization of enzyme catalyzed reduction of formaldehyde to methanol with synchronous cofactor regeneration.

    Science.gov (United States)

    Marpani, Fauziah; Sárossy, Zsuzsa; Pinelo, Manuel; Meyer, Anne S

    2017-12-01

    Enzymatic reduction of carbon dioxide (CO 2 ) to methanol (CH 3 OH) can be accomplished using a designed set-up of three oxidoreductases utilizing reduced pyridine nucleotide (NADH) as cofactor for the reducing equivalents electron supply. For this enzyme system to function efficiently a balanced regeneration of the reducing equivalents during reaction is required. Herein, we report the optimization of the enzymatic conversion of formaldehyde (CHOH) to CH 3 OH by alcohol dehydrogenase, the final step of the enzymatic redox reaction of CO 2 to CH 3 OH, with kinetically synchronous enzymatic cofactor regeneration using either glucose dehydrogenase (System I) or xylose dehydrogenase (System II). A mathematical model of the enzyme kinetics was employed to identify the best reaction set-up for attaining optimal cofactor recycling rate and enzyme utilization efficiency. Targeted process optimization experiments were conducted to verify the kinetically modeled results. Repetitive reaction cycles were shown to enhance the yield of CH 3 OH, increase the total turnover number (TTN) and the biocatalytic productivity rate (BPR) value for both system I and II whilst minimizing the exposure of the enzymes to high concentrations of CHOH. System II was found to be superior to System I with a yield of 8 mM CH 3 OH, a TTN of 160 and BPR of 24 μmol CH 3 OH/U · h during 6 hr of reaction. The study demonstrates that an optimal reaction set-up could be designed from rational kinetics modeling to maximize the yield of CH 3 OH, whilst simultaneously optimizing cofactor recycling and enzyme utilization efficiency. © 2017 Wiley Periodicals, Inc.

  4. Potential role of Arabidopsis PHP as an accessory subunit of the PAF1 transcriptional cofactor.

    Science.gov (United States)

    Park, Sunchung; Ek-Ramos, Maria Julissa; Oh, Sookyung; van Nocker, Steven

    2011-08-01

    Paf1C is a transcriptional cofactor that has been implicated in various transcription-associated mechanisms spanning initiation, elongation and RNA processing, and is important for multiple aspects of development in Arabidopsis. Our recent studies suggest Arabidopsis Paf1C is crucial for proper regulation of genes within H3K27me3-enriched chromatin, and that a protein named PHP may act as an accessory subunit of Paf1C that promotes this function.

  5. Metabolic Regulation of Histone Acetyltransferases by Endogenous Acyl-CoA Cofactors

    OpenAIRE

    Montgomery, David C.; Sorum, Alexander W.; Guasch, Laura; Nicklaus, Marc C.; Meier, Jordan L.

    2015-01-01

    The finding that chromatin modifications are sensitive to changes in cellular cofactor levels potentially links altered tumor cell metabolism and gene expression. However, the specific enzymes and metabolites that connect these two processes remain obscure. Characterizing these metabolic-epigenetic axes is critical to understanding how metabolism supports signaling in cancer, and developing therapeutic strategies to disrupt this process. Here, we describe a chemical approach to define the met...

  6. S-Adenosyl-L-Homocysteine Hydrolase Inhibition by a Synthetic Nicotinamide Cofactor Biomimetic

    Directory of Open Access Journals (Sweden)

    Lyn L. Kailing

    2018-03-01

    Full Text Available S-adenosyl-L-homocysteine (SAH hydrolases (SAHases are involved in the regulation of methylation reactions in many organisms and are thus crucial for numerous cellular functions. Consequently, their dysregulation is associated with severe health problems. The SAHase-catalyzed reaction is reversible and both directions depend on the redox activity of nicotinamide adenine dinucleotide (NAD+ as a cofactor. Therefore, nicotinamide cofactor biomimetics (NCB are a promising tool to modulate SAHase activity. In the present in vitro study, we investigated 10 synthetic truncated NAD+ analogs against a SAHase from the root-nodulating bacterium Bradyrhizobium elkanii. Among this set of analogs, one was identified to inhibit the SAHase in both directions. Isothermal titration calorimetry (ITC and crystallography experiments suggest that the inhibitory effect is not mediated by a direct interaction with the protein. Neither the apo-enzyme (i.e., deprived of the natural cofactor, nor the holo-enzyme (i.e., in the NAD+-bound state were found to bind the inhibitor. Yet, enzyme kinetics point to a non-competitive inhibition mechanism, where the inhibitor acts on both, the enzyme and enzyme-SAH complex. Based on our experimental results, we hypothesize that the NCB inhibits the enzyme via oxidation of the enzyme-bound NADH, which may be accessible through an open molecular gate, leaving the enzyme stalled in a configuration with oxidized cofactor, where the reaction intermediate can be neither converted nor released. Since the reaction mechanism of SAHase is quite uncommon, this kind of inhibition could be a viable pharmacological route, with a low risk of off-target effects. The NCB presented in this work could be used as a template for the development of more potent SAHase inhibitors.

  7. CD/MCD/VTVH-MCD Studies of Escherichia coli Bacterioferritin Support a Binuclear Iron Cofactor Site.

    Science.gov (United States)

    Kwak, Yeonju; Schwartz, Jennifer K; Huang, Victor W; Boice, Emily; Kurtz, Donald M; Solomon, Edward I

    2015-12-01

    Ferritins and bacterioferritins (Bfrs) utilize a binuclear non-heme iron binding site to catalyze oxidation of Fe(II), leading to formation of an iron mineral core within a protein shell. Unlike ferritins, in which the diiron site binds Fe(II) as a substrate, which then autoxidizes and migrates to the mineral core, the diiron site in Bfr has a 2-His/4-carboxylate ligand set that is commonly found in diiron cofactor enzymes. Bfrs could, therefore, utilize the diiron site as a cofactor rather than for substrate iron binding. In this study, we applied circular dichroism (CD), magnetic CD (MCD), and variable-temperature, variable-field MCD (VTVH-MCD) spectroscopies to define the geometric and electronic structures of the biferrous active site in Escherichia coli Bfr. For these studies, we used an engineered M52L variant, which is known to eliminate binding of a heme cofactor but to have very minor effects on either iron oxidation or mineral core formation. We also examined an H46A/D50A/M52L Bfr variant, which additionally disrupts a previously observed mononuclear non-heme iron binding site inside the protein shell. The spectral analyses define a binuclear and an additional mononuclear ferrous site. The biferrous site shows two different five-coordinate centers. After O2 oxidation and re-reduction, only the mononuclear ferrous signal is eliminated. The retention of the biferrous but not the mononuclear ferrous site upon O2 cycling supports a mechanism in which the binuclear site acts as a cofactor for the O2 reaction, while the mononuclear site binds the substrate Fe(II) that, after its oxidation to Fe(III), migrates to the mineral core.

  8. Quantum localization and protein-assisted vibrational energy flow in cofactors

    International Nuclear Information System (INIS)

    Leitner, David M

    2010-01-01

    Quantum effects influence vibrational dynamics and energy flow in biomolecules, which play a central role in biomolecule function, including control of reaction kinetics. Lifetimes of many vibrational modes of proteins and their temperature dependence, as determined by quantum golden-rule-based calculations, exhibit trends consistent with experimental observation and distinct from estimates based on classical modeling. Particularly notable are quantum coherence effects that give rise to localization of vibrational states of sizable organic molecules in the gas phase. Even when such a molecule, for instance a cofactor, is embedded in a protein, remnants of quantum localization survive that influence vibrational energy flow and its dependence on temperature. We discuss these effects on the mode-damping rates of a cofactor embedded in a protein, using the green fluorescent protein chromophore as a specific example. We find that for cofactors of this size embedded in their protein and solvent environment at room temperature a golden-rule calculation often overestimates the mode-damping rate.

  9. A live zebrafish-based screening system for human nuclear receptor ligand and cofactor discovery.

    Science.gov (United States)

    Tiefenbach, Jens; Moll, Pamela R; Nelson, Meryl R; Hu, Chun; Baev, Lilia; Kislinger, Thomas; Krause, Henry M

    2010-03-22

    Nuclear receptors (NRs) belong to a superfamily of transcription factors that regulate numerous homeostatic, metabolic and reproductive processes. Taken together with their modulation by small lipophilic molecules, they also represent an important and successful class of drug targets. Although many NRs have been targeted successfully, the majority have not, and one third are still orphans. Here we report the development of an in vivo GFP-based reporter system suitable for monitoring NR activities in all cells and tissues using live zebrafish (Danio rerio). The human NR fusion proteins used also contain a new affinity tag cassette allowing the purification of receptors with bound molecules from responsive tissues. We show that these constructs 1) respond as expected to endogenous zebrafish hormones and cofactors, 2) facilitate efficient receptor and cofactor purification, 3) respond robustly to NR hormones and drugs and 4) yield readily quantifiable signals. Transgenic lines representing the majority of human NRs have been established and are available for the investigation of tissue- and isoform-specific ligands and cofactors.

  10. A live zebrafish-based screening system for human nuclear receptor ligand and cofactor discovery.

    Directory of Open Access Journals (Sweden)

    Jens Tiefenbach

    2010-03-01

    Full Text Available Nuclear receptors (NRs belong to a superfamily of transcription factors that regulate numerous homeostatic, metabolic and reproductive processes. Taken together with their modulation by small lipophilic molecules, they also represent an important and successful class of drug targets. Although many NRs have been targeted successfully, the majority have not, and one third are still orphans. Here we report the development of an in vivo GFP-based reporter system suitable for monitoring NR activities in all cells and tissues using live zebrafish (Danio rerio. The human NR fusion proteins used also contain a new affinity tag cassette allowing the purification of receptors with bound molecules from responsive tissues. We show that these constructs 1 respond as expected to endogenous zebrafish hormones and cofactors, 2 facilitate efficient receptor and cofactor purification, 3 respond robustly to NR hormones and drugs and 4 yield readily quantifiable signals. Transgenic lines representing the majority of human NRs have been established and are available for the investigation of tissue- and isoform-specific ligands and cofactors.

  11. Crystallization and preliminary crystallographic analysis of molybdenum-cofactor biosynthesis protein C from Thermus thermophilus

    International Nuclear Information System (INIS)

    Kanaujia, Shankar Prasad; Ranjani, Chellamuthu Vasuki; Jeyakanthan, Jeyaraman; Baba, Seiki; Chen, Lirong; Liu, Zhi-Jie; Wang, Bi-Cheng; Nishida, Masami; Ebihara, Akio; Shinkai, Akeo; Kuramitsu, Seiki; Shiro, Yoshitsugu; Sekar, Kanagaraj; Yokoyama, Shigeyuki

    2006-01-01

    The molybdenum-cofactor biosynthesis protein C from T. thermophilus has been crystallized in two different space groups, P2 1 and R32; the crystals diffracted to 1.9 and 1.75 Å resolution, respectively. The Gram-negative aerobic eubacterium Thermus thermophilus is an extremely important thermophilic microorganism that was originally isolated from a thermal vent environment in Japan. The molybdenum cofactor in this organism is considered to be an essential component required by enzymes that catalyze diverse key reactions in the global metabolism of carbon, nitrogen and sulfur. The molybdenum-cofactor biosynthesis protein C derived from T. thermophilus was crystallized in two different space groups. Crystals obtained using the first crystallization condition belong to the monoclinic space group P2 1 , with unit-cell parameters a = 64.81, b = 109.84, c = 115.19 Å, β = 104.9°; the crystal diffracted to a resolution of 1.9 Å. The other crystal form belonged to space group R32, with unit-cell parameters a = b = 106.57, c = 59.25 Å, and diffracted to 1.75 Å resolution. Preliminary calculations reveal that the asymmetric unit contains 12 monomers and one monomer for the crystals belonging to space group P2 1 and R32, respectively

  12. CoFactor: Folate Requirement for Optimization of 5-Fluouracil Activity in Anticancer Chemotherapy

    Directory of Open Access Journals (Sweden)

    Muhammad Wasif Saif

    2010-01-01

    Full Text Available Intracellular reduced folate exists as a “pool” of more than 6 interconvertable forms. One of these forms, 5,10 methylenetetrahydrofolic acid (CH2THF, is the key one-carbon donor and reduced folate substrate for thymidylate synthase (TS. This pathway has been an important target for chemotherapy as it provides one of the necessary nucleotide substrates for DNA synthesis. The fluoropyrimidine 5-fluorouracil (5-FU exerts its main cytotoxic activity through TS inhibition. Leucovorin (5-formyltetrahydrofolate; LV has been used to increase the intracellular reduced folate pools and enhance TS inhibition. However, it must be metabolized within the cell through multiple intracellular enzymatic steps to form CH2THF. CoFactor (USAN fotrexorin calcium, (dl-5,10,-methylenepteroyl-monoglutamate calcium salt is a reduced folate that potentiates 5-FU cytotoxicity. According to early clinical trials, when 5-FU is modulated by CoFactor instead of LV, there is greater anti-tumor activity and less toxicity. This review presents the emerging role of CoFactor in colorectal and nongastrointestinal malignancies.

  13. Cofactor engineering to regulate NAD+/NADH ratio with its application to phytosterols biotransformation.

    Science.gov (United States)

    Su, Liqiu; Shen, Yanbing; Zhang, Wenkai; Gao, Tian; Shang, Zhihua; Wang, Min

    2017-10-30

    Cofactor engineering is involved in the modification of enzymes related to nicotinamide adenine dinucleotides (NADH and NAD + ) metabolism, which results in a significantly altered spectrum of metabolic products. Cofactor engineering plays an important role in metabolic engineering but is rarely reported in the sterols biotransformation process owing to its use of multi-catabolic enzymes, which promote multiple consecutive reactions. Androst-4-ene-3, 17-dione (AD) and androst-1, 4-diene-3, 17-dione (ADD) are important steroid medicine intermediates that are obtained via the nucleus oxidation and the side chain degradation of phytosterols by Mycobacterium. Given that the biotransformation from phytosterols to AD (D) is supposed to be a NAD + -dependent process, this work utilized cofactor engineering in Mycobacterium neoaurum and investigated the effect on cofactor and phytosterols metabolism. Through the addition of the coenzyme precursor of nicotinic acid in the phytosterols fermentation system, the intracellular NAD + /NADH ratio and the AD (D) production of M. neoaurum TCCC 11978 (MNR M3) were higher than in the control. Moreover, the NADH: flavin oxidoreductase was identified and was supposed to exert a positive effect on cofactor regulation and phytosterols metabolism pathways via comparative proteomic profiling of MNR cultured with and without phytosterols. In addition, the NADH: flavin oxidoreductase and a water-forming NADH oxidase from Lactobacillus brevis, were successfully overexpressed and heterologously expressed in MNR M3 to improve the intracellular ratio of NAD + /NADH. After 96 h of cultivation, the expression of these two enzymes in MNR M3 resulted in the decrease in intracellular NADH level (by 51 and 67%, respectively) and the increase in NAD + /NADH ratio (by 113 and 192%, respectively). Phytosterols bioconversion revealed that the conversion ratio of engineered stains was ultimately improved by 58 and 147%, respectively. The highest AD (D

  14. Efficacy and safety of cyclic pyranopterin monophosphate substitution in severe molybdenum cofactor deficiency type A : a prospective cohort study

    NARCIS (Netherlands)

    Schwahn, Bernd C.; Van Spronsen, Francjan J.; Belaidi, Abdel A.; Bowhay, Stephen; Christodoulou, John; Derks, Terry G.; Hennermann, Julia B.; Jameson, Elisabeth; Koenig, Kai; McGregor, Tracy L.; Font-Montgomery, Esperanza; Santamaria-Araujo, Jose A.; Santra, Saikat; Vaidya, Mamta; Vierzig, Anne; Wassmer, Evangeline; Weis, Ilona; Wong, Flora Y.; Veldman, Alex; Schwarz, Guenter

    2015-01-01

    Background Molybdenum cofactor deficiency (MoCD) is characterised by early, rapidly progressive postnatal encephalopathy and intractable seizures, leading to severe disability and early death. Previous treatment attempts have been unsuccessful. After a pioneering single treatment we now report the

  15. Redox-dependent substrate-cofactor interactions in the Michaelis-complex of a flavin-dependent oxidoreductase

    Science.gov (United States)

    Werther, Tobias; Wahlefeld, Stefan; Salewski, Johannes; Kuhlmann, Uwe; Zebger, Ingo; Hildebrandt, Peter; Dobbek, Holger

    2017-07-01

    How an enzyme activates its substrate for turnover is fundamental for catalysis but incompletely understood on a structural level. With redox enzymes one typically analyses structures of enzyme-substrate complexes in the unreactive oxidation state of the cofactor, assuming that the interaction between enzyme and substrate is independent of the cofactors oxidation state. Here, we investigate the Michaelis complex of the flavoenzyme xenobiotic reductase A with the reactive reduced cofactor bound to its substrates by X-ray crystallography and resonance Raman spectroscopy and compare it to the non-reactive oxidized Michaelis complex mimics. We find that substrates bind in different orientations to the oxidized and reduced flavin, in both cases flattening its structure. But only authentic Michaelis complexes display an unexpected rich vibrational band pattern uncovering a strong donor-acceptor complex between reduced flavin and substrate. This interaction likely activates the catalytic ground state of the reduced flavin, accelerating the reaction within a compressed cofactor-substrate complex.

  16. A water-forming NADH oxidase from Lactobacillus pentosus and its potential application in the regeneration of synthetic biomimetic cofactors

    Directory of Open Access Journals (Sweden)

    Claudia eNowak

    2015-09-01

    Full Text Available The cell-free biocatalytic production of fine chemicals by oxidoreductases has continuously grown over the past years. Since especially dehydrogenases depend on the stoichiometric use of nicotinamide pyridine cofactors, an integrated efficient recycling system is crucial to allow process operation under economic conditions. Lately, the variety of cofactors for biocatalysis was broadened by the utilization of totally synthetic and cheap biomimetics. Though, to date the regeneration has been limited to chemical or electrochemical methods. Here, we report an enzymatic recycling by the flavoprotein NADH-oxidase from Lactobacillus pentosus (LpNox. Since this enzyme has not been described before, we first characterized it in regard to its optimal reaction parameters. We found that the heterologously overexpressed enzyme only contained 13 % FAD. In vitro loading of the enzyme with FAD, resulted in a higher specific activity towards its natural cofactor NADH as well as different nicotinamide derived biomimetics. Apart from the enzymatic recycling, which gives water as a by-product by transferring four electrons onto oxygen, unbound FAD can also catalyse the oxidation of biomimetic cofactors. Here a two electron process takes place yielding H2O2 instead. The enzymatic and chemical recycling was compared in regard to reaction kinetics for the natural and biomimetic cofactors. With LpNox and FAD, two recycling strategies for biomimetic cofactors are described with either water or hydrogen peroxide as a by-product.

  17. Manipulating radicals: Using cobalt to steer radical reactions

    OpenAIRE

    Chirilă, A.

    2017-01-01

    This thesis describes research aimed at understanding and exploiting metallo-radical reactivity and explores reactions mediated by square planar, low-spin cobalt(II) complexes. A primary goal was to uncover novel reactivity of discrete cobalt(III)-bound carbene radicals generated upon reaction of the cobalt(II) catalysts with carbene precursors. Another important goal was to replace cobalt(II)-porphyrin catalysts with cheaper and easier to prepare metallo-radical analogues. Therefore the cata...

  18. Improving metabolic efficiency of the reverse beta-oxidation cycle by balancing redox cofactor requirement.

    Science.gov (United States)

    Wu, Junjun; Zhang, Xia; Zhou, Peng; Huang, Jiaying; Xia, Xiudong; Li, Wei; Zhou, Ziyu; Chen, Yue; Liu, Yinghao; Dong, Mingsheng

    2017-11-01

    Previous studies have made many exciting achievements on pushing the functional reversal of beta-oxidation cycle (r-BOX) to more widespread adoption for synthesis of a wide variety of fuels and chemicals. However, the redox cofactor requirement for the efficient operation of r-BOX remains unclear. In this work, the metabolic efficiency of r-BOX for medium-chain fatty acid (C 6 -C 10 , MCFA) production was optimized by redox cofactor engineering. Stoichiometric analysis of the r-BOX pathway and further experimental examination identified NADH as a crucial determinant of r-BOX process yield. Furthermore, the introduction of formate dehydrogenase from Candida boidinii using fermentative inhibitor byproduct formate as a redox NADH sink improved MCFA titer from initial 1.2g/L to 3.1g/L. Moreover, coupling of increasing the supply of acetyl-CoA with NADH to achieve fermentative redox balance enabled product synthesis at maximum titers. To this end, the acetate re-assimilation pathway was further optimized to increase acetyl-CoA availability associated with the new supply of NADH. It was found that the acetyl-CoA synthetase activity and intracellular ATP levels constrained the activity of acetate re-assimilation pathway, and 4.7g/L of MCFA titer was finally achieved after alleviating these two limiting factors. To the best of our knowledge, this represented the highest titer reported to date. These results demonstrated that the key constraint of r-BOX was redox imbalance and redox engineering could further unleash the lipogenic potential of this cycle. The redox engineering strategies could be applied to acetyl-CoA-derived products or other bio-products requiring multiple redox cofactors for biosynthesis. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  19. Dissociation of activated protein C functions by elimination of protein S cofactor enhancement.

    LENUS (Irish Health Repository)

    Harmon, Shona

    2008-11-07

    Activated protein C (APC) plays a critical anticoagulant role in vivo by inactivating procoagulant factor Va and factor VIIIa and thus down-regulating thrombin generation. In addition, APC bound to the endothelial cell protein C receptor can initiate protease-activated receptor-1 (PAR-1)-mediated cytoprotective signaling. Protein S constitutes a critical cofactor for the anticoagulant function of APC but is not known to be involved in regulating APC-mediated protective PAR-1 signaling. In this study we utilized a site-directed mutagenesis strategy to characterize a putative protein S binding region within the APC Gla domain. Three single amino acid substitutions within the APC Gla domain (D35T, D36A, and A39V) were found to mildly impair protein S-dependent anticoagulant activity (<2-fold) but retained entirely normal cytoprotective activity. However, a single amino acid substitution (L38D) ablated the ability of protein S to function as a cofactor for this APC variant. Consequently, in assays of protein S-dependent factor Va proteolysis using purified proteins or in the plasma milieu, APC-L38D variant exhibited minimal residual anticoagulant activity compared with wild type APC. Despite the location of Leu-38 in the Gla domain, APC-L38D interacted normally with endothelial cell protein C receptor and retained its ability to trigger PAR-1 mediated cytoprotective signaling in a manner indistinguishable from that of wild type APC. Consequently, elimination of protein S cofactor enhancement of APC anticoagulant function represents a novel and effective strategy by which to separate the anticoagulant and cytoprotective functions of APC for potential therapeutic gain.

  20. Biochemical and genetic characterization of three molybdenum cofactor hydroxylases in Arabidopsis thaliana

    DEFF Research Database (Denmark)

    Hoff, Tine; Frandsen, Gitte Inselmann; Rocher, Anne

    1998-01-01

    Aldehyde oxidases and xanthine dehydrogenases/oxidases belong to the molybdenum cofactor dependent hydroxylase class of enzymes. Zymograms show that Arabidopsis thaliana has at least three different aldehyde oxidases and one xanthine oxidase. Three different cDNA clones encoding putative aldehyde...... oxidases (AtAO1, 2, 3) were isolated. An aldehyde oxidase is the last step in abscisic acid (ABA) biosynthesis. AtAO1 is mainly expressed in seeds and roots which might reflect that it is involved in ABA biosynthesis....

  1. Crystallographic investigation of the cooperative interaction between trimethoprim, reduced cofactor and dihydrofolate reductase

    International Nuclear Information System (INIS)

    Champness, J.N.; Stammers, D.K.; Beddell, C.R.

    1986-01-01

    The structure of the complex between E. coli form I dihydrofolate reductase, the antibacterial trimethoprim and NADPH has been determined by X-ray crystallography. The inhibitor and cofactor are in mutual contact. A flexible chain segment which includes Met 20 is in contact with the inhibitor in the presence of NADPH, but more distant in its absence. By contrast, the inhibitor conformation is little changed with NADPH present. The authors discuss these observations with regard to the mutually cooperative binding of these ligands to the protein, and to the associated enhancement of inhibitory selectivity shown by trimethoprim for bacterial as opposed to vertebrate enzyme. (Auth.)

  2. Markers, Cofactors and Staging Systems in the Study of HIV Disease Progression: A Review

    Directory of Open Access Journals (Sweden)

    MC Portela

    1997-07-01

    Full Text Available This paper is aimed at providing a comprehensive review of markers, cofactors and staging systems used for HIV disease, focusing on some aspects that nowadays could even be considered historical, and advancing in current issues such as the prognostic value of viral load measurements, viral genotypic and phenotypic characterization, and new HIV disease treatment protocols. CD4+ cell values, combined with the new viral markers mentioned are promising as a parsimonious predictor set for defining both severity and progression. An adequate predictor of patient resource use for planning purposes still needs to be defined

  3. Cofactor-binding sites in proteins of deviating sequence: comparative analysis and clustering in torsion angle, cavity, and fold space.

    Science.gov (United States)

    Stegemann, Björn; Klebe, Gerhard

    2012-02-01

    Small molecules are recognized in protein-binding pockets through surface-exposed physicochemical properties. To optimize binding, they have to adopt a conformation corresponding to a local energy minimum within the formed protein-ligand complex. However, their conformational flexibility makes them competent to bind not only to homologous proteins of the same family but also to proteins of remote similarity with respect to the shape of the binding pockets and folding pattern. Considering drug action, such observations can give rise to unexpected and undesired cross reactivity. In this study, datasets of six different cofactors (ADP, ATP, NAD(P)(H), FAD, and acetyl CoA, sharing an adenosine diphosphate moiety as common substructure), observed in multiple crystal structures of protein-cofactor complexes exhibiting sequence identity below 25%, have been analyzed for the conformational properties of the bound ligands, the distribution of physicochemical properties in the accommodating protein-binding pockets, and the local folding patterns next to the cofactor-binding site. State-of-the-art clustering techniques have been applied to group the different protein-cofactor complexes in the different spaces. Interestingly, clustering in cavity (Cavbase) and fold space (DALI) reveals virtually the same data structuring. Remarkable relationships can be found among the different spaces. They provide information on how conformations are conserved across the host proteins and which distinct local cavity and fold motifs recognize the different portions of the cofactors. In those cases, where different cofactors are found to be accommodated in a similar fashion to the same fold motifs, only a commonly shared substructure of the cofactors is used for the recognition process. Copyright © 2011 Wiley Periodicals, Inc.

  4. Cervical carcinogenesis: the role of co-factors and generation of reactive oxygen species Carcinogénesis cervical: co-factores y antioxidantes

    Directory of Open Access Journals (Sweden)

    Anna Giuliano

    2003-01-01

    Full Text Available Several HPV co-factors have been proposed, some more or less consistently associated with cervical dysplasia and cancer risk. More research, using prospective cohort designs, is needed to further describe where in carcinogenesis these factors are working and to assess the biological mechanism of these factors. In addition, further research is needed to define the role of various hormonal contraceptive formulations in promoting cervical carcinogenesis. While many interesting scientific questions remain to be answered, results from the numerous epidemiological studies conducted to date indicate that cervical dysplasia and cancer may be reduced if the oxidant antioxidant ratio is shifted to more of and antioxidant profile. In addition to cervical cancer screening, a reduction in cervical cancer incidence may be accomplished by reducing tobacco use, increasing nutritional status, and utilizing barrier contraception to prevent infection with other sexually acquired infections.Diversos co-factores de riesgo han sido asociados consistentemente con displasia cervical y cáncer invasor. Es necesario un mayor número de investigaciones que utilicen diseños de cohorte prospectivos para describir el proceso de carcinogénesis y el mecanismo biológico de cada uno de estos factores. Adicionalmente, futuras investigaciones serán necesarias para definir el papel de los anticonceptivos hormonales en la promoción de la carcinogénesis cervical. Mientras que muchas preguntas científicas interesantes permanecen sin ser respondidas, resultados de numerosos estudios epidemiológicos que se desarrollan actualmente, indican que la displasia cervical y cáncer podrán ser reducidos si la tasa de oxidantes-antioxidantes es cambiada a más de un perfil antioxidante. Además de la detección oportuna de cáncer cervical, puede lograrse una reducción de la incidencia de esta enfermedad disminuyendo el consumo de tabaco, incrementando el estatus nutricional, y

  5. Hydroxyl radical reactivity with diethylhydroxylamine

    International Nuclear Information System (INIS)

    Gorse, R.A. Jr.; Lii, R.R.; Saunders, B.B.

    1977-01-01

    Diethylhydroxylamine (DEHA) reacts with gas-phase hydroxyl radicals on every third collision, whereas the corresponding reaction in aqueous solution is considerably slower. The high gas-phase reactivity explains the predicted inhibitory effect of DEHA in atmospheric smog processes. Results from the studies in the aqueous phase are helpful in predicting the mechanism of the reaction of DEHA with hydroxyl radicals

  6. Muoniated acyl and thioacyl radicals

    International Nuclear Information System (INIS)

    McKenzie, Iain; Brodovitch, Jean-Claude; Ghandi, Khashayar; Percival, Paul W.

    2006-01-01

    The product of the reaction of muonium with tert-butylisocyanate was previously assigned as the muoniated tert-butylaminyl radical (I. McKenzie, J.-C. Brodovitch, K. Ghandi, S. Kecman, P. W. Percival, Physica B 326 (2003) 76). This assignment is incorrect since the muon and 14 N hyperfine-coupling constants (hfcc) of this radical would have the opposite sign, which is in conflict with the experimental results. The radical is now reassigned as the muoniated N-tert-butylcarbamoyl radical, based on the similarities between the experimental muon and 14 N hfcc and hfcc calculated at the UB3LYP/6-311G(d,p)//UB3LYP/EPR-III level. The large zero-point energy in the N-Mu bond results in the dissociation barrier of the muoniated N-tert-butylcarbamoyl radical being above the combined energy of the reactants, in contrast to the N-tert-butylcarbamoyl radical where the dissociation barrier lies below the combined energy of the reactants. The reaction of muonium with tert-butylisothiocyanate produced both conformers of the muoniated N-tert-butylthiocarbamoyl radical and their assignment was based on the similarities between the experimental and calculated muon hfcc. These are the first acyl and thioacyl radicals to be directly detected by muon spin spectroscopy

  7. Muoniated acyl and thioacyl radicals

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, Iain [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Brodovitch, Jean-Claude [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Ghandi, Khashayar [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Percival, Paul W. [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada)]. E-mail: percival@sfu.ca

    2006-03-31

    The product of the reaction of muonium with tert-butylisocyanate was previously assigned as the muoniated tert-butylaminyl radical (I. McKenzie, J.-C. Brodovitch, K. Ghandi, S. Kecman, P. W. Percival, Physica B 326 (2003) 76). This assignment is incorrect since the muon and {sup 14}N hyperfine-coupling constants (hfcc) of this radical would have the opposite sign, which is in conflict with the experimental results. The radical is now reassigned as the muoniated N-tert-butylcarbamoyl radical, based on the similarities between the experimental muon and {sup 14}N hfcc and hfcc calculated at the UB3LYP/6-311G(d,p)//UB3LYP/EPR-III level. The large zero-point energy in the N-Mu bond results in the dissociation barrier of the muoniated N-tert-butylcarbamoyl radical being above the combined energy of the reactants, in contrast to the N-tert-butylcarbamoyl radical where the dissociation barrier lies below the combined energy of the reactants. The reaction of muonium with tert-butylisothiocyanate produced both conformers of the muoniated N-tert-butylthiocarbamoyl radical and their assignment was based on the similarities between the experimental and calculated muon hfcc. These are the first acyl and thioacyl radicals to be directly detected by muon spin spectroscopy.

  8. Discovery and validation of information theory-based transcription factor and cofactor binding site motifs.

    Science.gov (United States)

    Lu, Ruipeng; Mucaki, Eliseos J; Rogan, Peter K

    2017-03-17

    Data from ChIP-seq experiments can derive the genome-wide binding specificities of transcription factors (TFs) and other regulatory proteins. We analyzed 765 ENCODE ChIP-seq peak datasets of 207 human TFs with a novel motif discovery pipeline based on recursive, thresholded entropy minimization. This approach, while obviating the need to compensate for skewed nucleotide composition, distinguishes true binding motifs from noise, quantifies the strengths of individual binding sites based on computed affinity and detects adjacent cofactor binding sites that coordinate with the targets of primary, immunoprecipitated TFs. We obtained contiguous and bipartite information theory-based position weight matrices (iPWMs) for 93 sequence-specific TFs, discovered 23 cofactor motifs for 127 TFs and revealed six high-confidence novel motifs. The reliability and accuracy of these iPWMs were determined via four independent validation methods, including the detection of experimentally proven binding sites, explanation of effects of characterized SNPs, comparison with previously published motifs and statistical analyses. We also predict previously unreported TF coregulatory interactions (e.g. TF complexes). These iPWMs constitute a powerful tool for predicting the effects of sequence variants in known binding sites, performing mutation analysis on regulatory SNPs and predicting previously unrecognized binding sites and target genes. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  9. How Diverse are the Protein-Bound Conformations of Small-Molecule Drugs and Cofactors?

    Science.gov (United States)

    Friedrich, Nils-Ole; Simsir, Méliné; Kirchmair, Johannes

    2018-03-01

    Knowledge of the bioactive conformations of small molecules or the ability to predict them with theoretical methods is of key importance to the design of bioactive compounds such as drugs, agrochemicals and cosmetics. Using an elaborate cheminformatics pipeline, which also evaluates the support of individual atom coordinates by the measured electron density, we compiled a complete set (“Sperrylite Dataset”) of high-quality structures of protein-bound ligand conformations from the PDB. The Sperrylite Dataset consists of a total of 10,936 high-quality structures of 4548 unique ligands. Based on this dataset, we assessed the variability of the bioactive conformations of 91 small molecules—each represented by a minimum of ten structures—and found it to be largely independent of the number of rotatable bonds. Sixty-nine molecules had at least two distinct conformations (defined by an RMSD greater than 1 Å). For a representative subset of 17 approved drugs and cofactors we observed a clear trend for the formation of few clusters of highly similar conformers. Even for proteins that share a very low sequence identity, ligands were regularly found to adopt similar conformations. For cofactors, a clear trend for extended conformations was measured, although in few cases also coiled conformers were observed. The Sperrylite Dataset is available for download from http://www.zbh.uni-hamburg.de/sperrylite_dataset.

  10. Human HOX Proteins Use Diverse and Context-Dependent Motifs to Interact with TALE Class Cofactors.

    Science.gov (United States)

    Dard, Amélie; Reboulet, Jonathan; Jia, Yunlong; Bleicher, Françoise; Duffraisse, Marilyne; Vanaker, Jean-Marc; Forcet, Christelle; Merabet, Samir

    2018-03-13

    HOX proteins achieve numerous functions by interacting with the TALE class PBX and MEIS cofactors. In contrast to this established partnership in development and disease, how HOX proteins could interact with PBX and MEIS remains unclear. Here, we present a systematic analysis of HOX/PBX/MEIS interaction properties, scanning all paralog groups with human and mouse HOX proteins in vitro and in live cells. We demonstrate that a previously characterized HOX protein motif known to be critical for HOX-PBX interactions becomes dispensable in the presence of MEIS in all except the two most anterior paralog groups. We further identify paralog-specific TALE-binding sites that are used in a highly context-dependent manner. One of these binding sites is involved in the proliferative activity of HOXA7 in breast cancer cells. Together these findings reveal an extraordinary level of interaction flexibility between HOX proteins and their major class of developmental cofactors. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  11. Neutrino mass matrices with two vanishing cofactors and Fritzsch texture for charged lepton mass matrix

    Science.gov (United States)

    Wang, Weijian; Guo, Shu-Yuan; Wang, Zhi-Gang

    2016-04-01

    In this paper, we study the cofactor 2 zero neutrino mass matrices with the Fritzsch-type structure in charged lepton mass matrix (CLMM). In the numerical analysis, we perform a scan over the parameter space of all the 15 possible patterns to get a large sample of viable scattering points. Among the 15 possible patterns, three of them can accommodate the latest lepton mixing and neutrino mass data. We compare the predictions of the allowed patterns with their counterparts with diagonal CLMM. In this case, the severe cosmology bound on the neutrino mass set a strong constraint on the parameter space, rendering two patterns only marginally allowed. The Fritzsch-type CLMM will have impact on the viable parameter space and give rise to different phenomenological predictions. Each allowed pattern predicts the strong correlations between physical variables, which is essential for model selection and can be probed in future experiments. It is found that under the no-diagonal CLMM, the cofactor zeros structure in neutrino mass matrix is unstable as the running of renormalization group (RG) from seesaw scale to the electroweak scale. A way out of the problem is to propose the flavor symmetry under the models with a TeV seesaw scale. The inverse seesaw model and a loop-induced model are given as two examples.

  12. A DEAD box protein facilitates HIV-1 replication as a cellular co-factor of Rev

    International Nuclear Information System (INIS)

    Fang Jianhua; Kubota, Satoshi; Yang Bin; Zhou Naiming; Zhang Hui; Godbout, Roseline; Pomerantz, Roger J.

    2004-01-01

    HIV-1 Rev escorts unspliced viral mRNAs out of the nucleus of infected cells, which allows formation of infectious HIV-1 virions. We have identified a putative DEAD box (Asp-Glu-Ala-Asp) RNA helicase, DDX1, as a cellular co-factor of Rev, through yeast and mammalian two-hybrid systems using the N-terminal motif of Rev as 'bait'. DDX1 is not a functional homolog of HIV-1 Rev, but down-regulation of DDX1 resulted in an alternative splicing pattern of Rev-responsive element (RRE)-containing mRNA, and attenuation of Gag p24 antigen production from HLfb rev(-) cells rescued by exogenous Rev. Co-transfection of a DDX1 expression vector with HIV-1 significantly increased viral production. DDX1 binding to Rev, as well as to the RRE, strongly suggest that DDX1 affects Rev function through the Rev-RRE axis. Moreover, down-regulation of DDX1 altered the steady state subcellular distribution of Rev, from nuclear/nucleolar to cytoplasmic dominance. These findings indicate that DDX1 is a critical cellular co-factor for Rev function, which maintains the proper subcellular distribution of this lentiviral regulatory protein. Therefore, alterations in DDX1-Rev interactions could induce HIV-1 persistence and targeting DDX1 may lead to rationally designed and novel anti-HIV-1 strategies and therapeutics

  13. Live Cell Discovery of Microbial Vitamin Transport and Enzyme-Cofactor Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Lindsey N.; Koech, Phillip K.; Plymale, Andrew E.; Landorf, Elizabeth V.; Konopka, Allan; Collart, Frank; Lipton, Mary S.; Romine, Margaret F.; Wright, Aaron T.

    2016-02-02

    The rapid completion of microbial genomes is inducing a conundrum in functional gene discovery. Novel methods are critically needed to shorten the gap between characterizing a microbial genome and experimentally validating bioinformatically-predicted functions. Of particular importance are transport mechanisms, used to shuttle nutrients and metabolites across cell mem-branes, such as B vitamins, which are indispensable to metabolic reactions crucial to the survival of diverse microbes ranging from members of environmental microbial communities to human pathogens. Methods to accurately assign function and specificity for a wide range of experimentally unidentified and/or predicted membrane-embedded transport proteins, and characterization of intra-cellular enzyme-cofactor/nutrient associations are needed to enable a significantly improved understanding of microbial biochemis-try and physiology, how microbes associate with others, and how they sense and respond to environmental perturbations. Chemical probes derived from B vitamins B1, B2, and B7 have allowed us to experimentally address the aforementioned needs by identifying B vitamin transporters and intracellular protein-cofactor associations through live cell labeling of the filamentous anoxygenic pho-toheterotroph, Chloroflexus aurantiacus J-10-fl, known for both B vitamin biosynthesis and environmental salvage. Our probes provide a unique opportunity to directly link cellular activity and protein function back to ecosystem and/or host dynamics by iden-tifying B vitamin transport and disposition mechanisms required for survival.

  14. Influence of common mucosal co-factors on HIV infection in the female genital tract.

    Science.gov (United States)

    Ferreira, Victor H; Kafka, Jessica K; Kaushic, Charu

    2014-06-01

    Women constitute almost half of HIV-infected population globally, and the female genital tract (FGT) accounts for approximately 40% of all new HIV infections worldwide. The FGT is composed of upper and lower parts, distinct in their morphological and functional characteristics. Co-factors in the genital microenvironment, such as presence of hormones, semen, and other sexually transmitted infections, can facilitate or deter HIV infection and play a critical role in determining susceptibility to HIV. In this review, we examine some of these co-factors and their potential influence. Presence of physical and chemical barriers such as epithelial tight junctions, mucus, and anti-microbial peptides can actively block and inhibit viral replication, presenting a significant deterrent to HIV. Upon exposure, HIV and other pathogens first encounter the genital epithelium: cells that express a wide repertoire of pattern recognition receptors that can recognize and directly initiate innate immune responses. These and other interactions in the genital tract can lead to direct and indirect inflammation and enhance the number of local target cells, immune activation, and microbial translocation, all of which promote HIV infection and replication. Better understanding of the dynamics of HIV transmission in the female genital tract would be invaluable for improving the design of prophylactic strategies against HIV. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Deducing the temporal order of cofactor function in ligand-regulated gene transcription: theory and experimental verification.

    Science.gov (United States)

    Dougherty, Edward J; Guo, Chunhua; Simons, S Stoney; Chow, Carson C

    2012-01-01

    Cofactors are intimately involved in steroid-regulated gene expression. Two critical questions are (1) the steps at which cofactors exert their biological activities and (2) the nature of that activity. Here we show that a new mathematical theory of steroid hormone action can be used to deduce the kinetic properties and reaction sequence position for the functioning of any two cofactors relative to a concentration limiting step (CLS) and to each other. The predictions of the theory, which can be applied using graphical methods similar to those of enzyme kinetics, are validated by obtaining internally consistent data for pair-wise analyses of three cofactors (TIF2, sSMRT, and NCoR) in U2OS cells. The analysis of TIF2 and sSMRT actions on GR-induction of an endogenous gene gave results identical to those with an exogenous reporter. Thus new tools to determine previously unobtainable information about the nature and position of cofactor action in any process displaying first-order Hill plot kinetics are now available.

  16. Radical production in biological systems

    International Nuclear Information System (INIS)

    Johnson, J.R.; Akabani, G.

    1994-10-01

    This paper describes our effort to develop a metric for radiation exposure that is more fundamental than adsorbed dose and upon which a metric for exposure to chemicals could be based. This metric is based on the production of radicals by the two agents. Radicals produced by radiation in biological systems commonly assumed to be the same as those produced in water despite the presence of a variety of complex molecules. This may explain why the extensive efforts to describe the relationship between energy deposition (track structure) and molecular damage to DNA, based on the spectrum of radicals produced, have not been successful in explaining simple biological effects such as cell killing. Current models assume that DNA and its basic elements are immersed in water-like media and only model the production and diffusion of water-based radicals and their interaction with DNA structures; these models lack the cross sections associated with each macro-component of DNA and only treat water-based radicals. It has been found that such models are not realistic because DNA is not immersed in pure water. A computer code capable of simulating electron tracks, low-energy electrons, energy deposition in small molecules, and radical production and diffusion in water like media has been developed. This code is still in at a primitive stage and development is continuing. It is being used to study radical production by radiation, and radical diffusion and interactions in simple molecular systems following their production. We are extending the code to radical production by chemicals to complement our PBPK modeling efforts. It therefore has been developed primarily for use with radionuclides that are in biological materials, and not for radiation fields

  17. Guest Editorial: Processes of Radicalization and De-Radicalization

    Directory of Open Access Journals (Sweden)

    Donatella Della Porta

    2012-05-01

    Full Text Available The study of radicalization and de-radicalization, understood as processes leading towards the increased or decreased use of political violence, is central to the question of how political violence emerges, how it can be prevented, and how it can be contained. The focus section of this issue of the International Journal of Conflict and Violence addresses radicalization and de-radicalization, seeking to develop a more comprehensive understanding of the processes, dynamics, and mechanisms involved and taking an interdisciplinary approach to overcome the fragmentation into separate disciplines and focus areas. Contributions by Pénélope Larzillière, Felix Heiduk, Bill Kissane, Hank Johnston, Christian Davenport and Cyanne Loyle, Veronique Dudouet, and Lasse Lindekilde address repressive settings, legitimacy, institutional aspects, organizational outcomes, and dynamics in Europe, Asia, Africa, and North and South America.

  18. Redox properties of free radicals

    International Nuclear Information System (INIS)

    Neta, P.

    1981-01-01

    Results of electron transfer reactions observed and monitored by pulse radiolysis are reported. This technique allows determination of the first one-electron reduction or oxidation of a compound rather than the overall two-electron transfer usually reported. Pulse radiolysis allows the determination of absolute rate constants for reactions of free radicals and helps elucidate the mechanisms involved. Studies using this technique to study radicals derived from quinones, nitro compounds, pyridines, phenols, and anilines are reported. Radicals of biochemical interest arising from riboflavin, ascorbic acid, vitamin K 3 , vitamin E, MAD + , porphyrins, etc. have also been studied

  19. Hot wire radicals and reactions

    International Nuclear Information System (INIS)

    Zheng Wengang; Gallagher, Alan

    2006-01-01

    Threshold ionization mass spectroscopy is used to measure radical (and stable gas) densities at the substrate of a tungsten hot wire (HW) reactor. We report measurements of the silane reaction probability on the HW and the probability of Si and H release from the HW. We describe a model for the atomic H release, based on the H 2 dissociation model. We note major variations in silicon-release, with dependence on prior silane exposure. Measured radical densities versus silane pressure yield silicon-silane and H-silane reaction rate coefficients, and the dominant radical fluxes to the substrate

  20. Quantification of methanogenic biomass by enzyme-linked immunosorbent assay and by analysis of specific methanogenic cofactors

    Energy Technology Data Exchange (ETDEWEB)

    Gorris, L G.M.; Kemp, H A; Archer, D B

    1987-01-01

    The reliability and accuracy with which enzyme-linked immunosorbent assay (ELISA) and an assay of methanogenic cofactors detect and quantify methanogenic species were investigated. Both assays required standardization with laboratory cultures of methanogenic bacteria and were applied to mixtures of pure cultures and samples from anaerobic digesters. ELISA was shown to be a simple method for detecting and quantifying individual methanogenic species. The range of species which can be assayed is limited by the range of antisera available but, potentially, ELISA can be applied to all methanogens. Although the cofactor assay is not species-specific it can distinguish hydrogenotrophic and acetotrophic methanogens and is quantitative.

  1. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2013-01-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  2. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2014-07-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  3. Why Nature Uses Radical SAM Enzymes so Widely: Electron Nuclear Double Resonance Studies of Lysine 2,3-Aminomutase Show the 5'-dAdo• "Free Radical" Is Never Free.

    Science.gov (United States)

    Horitani, Masaki; Byer, Amanda S; Shisler, Krista A; Chandra, Tilak; Broderick, Joan B; Hoffman, Brian M

    2015-06-10

    Lysine 2,3-aminomutase (LAM) is a radical S-adenosyl-L-methionine (SAM) enzyme and, like other members of this superfamily, LAM utilizes radical-generating machinery comprising SAM anchored to the unique Fe of a [4Fe-4S] cluster via a classical five-membered N,O chelate ring. Catalysis is initiated by reductive cleavage of the SAM S-C5' bond, which creates the highly reactive 5'-deoxyadenosyl radical (5'-dAdo•), the same radical generated by homolytic Co-C bond cleavage in B12 radical enzymes. The SAM surrogate S-3',4'-anhydroadenosyl-L-methionine (anSAM) can replace SAM as a cofactor in the isomerization of L-α-lysine to L-β-lysine by LAM, via the stable allylic anhydroadenosyl radical (anAdo•). Here electron nuclear double resonance (ENDOR) spectroscopy of the anAdo• radical in the presence of (13)C, (2)H, and (15)N-labeled lysine completes the picture of how the active site of LAM from Clostridium subterminale SB4 "tames" the 5'-dAdo• radical, preventing it from carrying out harmful side reactions: this "free radical" in LAM is never free. The low steric demands of the radical-generating [4Fe-4S]/SAM construct allow the substrate target to bind adjacent to the S-C5' bond, thereby enabling the 5'-dAdo• radical created by cleavage of this bond to react with its partners by undergoing small motions, ∼0.6 Å toward the target and ∼1.5 Å overall, that are controlled by tight van der Waals contact with its partners. We suggest that the accessibility to substrate and ready control of the reactive C5' radical, with "van der Waals control" of small motions throughout the catalytic cycle, is common within the radical SAM enzyme superfamily and is a major reason why these enzymes are the preferred means of initiating radical reactions in nature.

  4. Halogens are key cofactors in building of collagen IV scaffolds outside the cell.

    Science.gov (United States)

    Brown, Kyle L; Hudson, Billy G; Voziyan, Paul A

    2018-05-01

    The purpose of this review is to highlight recent advances in understanding the molecular assembly of basement membranes, as exemplified by the glomerular basement membrane (GBM) of the kidney filtration apparatus. In particular, an essential role of halogens in the basement membrane formation has been discovered. Extracellular chloride triggers a molecular switch within non collagenous domains of collagen IV that induces protomer oligomerization and scaffold assembly outside the cell. Moreover, bromide is an essential cofactor in enzymatic cross-linking that reinforces the stability of scaffolds. Halogenation and halogen-induced oxidation of the collagen IV scaffold in disease states damage scaffold function. Halogens play an essential role in the formation of collagen IV scaffolds of basement membranes. Pathogenic damage of these scaffolds by halogenation and halogen-induced oxidation is a potential target for therapeutic interventions.

  5. Roles of Fe-S proteins: from cofactor synthesis to iron homeostasis to protein synthesis.

    Science.gov (United States)

    Pain, Debkumar; Dancis, Andrew

    2016-06-01

    Fe-S cluster assembly is an essential process for all cells. Impairment of Fe-S cluster assembly creates diseases in diverse and surprising ways. In one scenario, the loss of function of lipoic acid synthase, an enzyme with Fe-S cluster cofactor in mitochondria, impairs activity of various lipoamide-dependent enzymes with drastic consequences for metabolism. In a second scenario, the heme biosynthetic pathway in red cell precursors is specifically targeted, and iron homeostasis is perturbed, but lipoic acid synthesis is unaffected. In a third scenario, tRNA modifications arising from action of the cysteine desulfurase and/or Fe-S cluster proteins are lost, which may lead to impaired protein synthesis. These defects can then result in cancer, neurologic dysfunction or type 2 diabetes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Proteolytic activation transforms heparin cofactor II into a host defense molecule.

    Science.gov (United States)

    Kalle, Martina; Papareddy, Praveen; Kasetty, Gopinath; Tollefsen, Douglas M; Malmsten, Martin; Mörgelin, Matthias; Schmidtchen, Artur

    2013-06-15

    The abundant serine proteinase inhibitor heparin cofactor II (HCII) has been proposed to inhibit extravascular thrombin. However, the exact physiological role of this plasma protein remains enigmatic. In this study, we demonstrate a previously unknown role for HCII in host defense. Proteolytic cleavage of the molecule induced a conformational change, thereby inducing endotoxin-binding and antimicrobial properties. Analyses employing representative peptide epitopes mapped these effects to helices A and D. Mice deficient in HCII showed increased susceptibility to invasive infection by Pseudomonas aeruginosa, along with a significantly increased cytokine response. Correspondingly, decreased levels of HCII were observed in wild-type animals challenged with bacteria or endotoxin. In humans, proteolytically cleaved HCII forms were detected during wounding and in association with bacteria. Thus, the protease-induced uncovering of cryptic epitopes in HCII, which transforms the molecule into a host defense factor, represents a previously unknown regulatory mechanism in HCII biology and innate immunity.

  7. Cofactor specificity switch in Shikimate dehydrogenase by rational design and consensus engineering.

    Science.gov (United States)

    García-Guevara, Fernando; Bravo, Iris; Martínez-Anaya, Claudia; Segovia, Lorenzo

    2017-08-01

    Consensus engineering has been used to design more stable variants using the most frequent amino acid at each site of a multiple sequence alignment; sometimes consensus engineering modifies function, but efforts have mainly been focused on studying stability. Here we constructed a consensus Rossmann domain for the Shikimate dehydrogenase enzyme; separately we decided to switch the cofactor specificity through rational design in the Escherichia coli Shikimate dehydrogenase enzyme and then analyzed the effect of consensus mutations on top of our design. We found that consensus mutations closest to the 2' adenine moiety increased the activity in our design. Consensus engineering has been shown to result in more stable proteins and our findings suggest it could also be used as a complementary tool for increasing or modifying enzyme activity during design. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  8. Characterization of a "TRAMP-like" co-factor of the human RNA exosome

    DEFF Research Database (Denmark)

    Christensen, Marianne Skovgaard; Kristiansen, Maiken Søndergaard; Lubas, Michal Szymon

    Genome-wide studies in yeast, plants and humans have revealed numerous new transcripts in what was previously thought to be silent DNA or junk DNA. One class of non-coding transcript discovered recently is the PROMoter uPstream Transcripts (PROMPTs), which is only seen upon depletion of the RNA...... exosome, the major 3’-5’ exonuclease complex in human cells. PROMPTs have a lot in common with the yeast Cryptic Unstable Transcripts (CUTs), which are degraded by the concerted effort of the exosome, and its co-factor complex TRAMP (Trf4p/Air1p/Mtr4p). We have identified human proteins with functional...... similarities to components of the yeast TRAMP complex, and show that these are involved in the degradation of PROMPTs. While, these proteins form transient complexes with the exosome, our preliminary results also indicate that complex formation can occur directly with catalytic components of the exosome...

  9. Characterization of water-forming NADH oxidases for co-factor regeneration

    DEFF Research Database (Denmark)

    Rehn, Gustav; Pedersen, Asbjørn Toftgaard; J. Charnock, Simon

    an environmentaland economic perspective [1]. Alcohol dehydrogenases (ADH) offer one such alternative. However, the reaction requires the oxidized nicotinamide co-factor (NAD+) that must be recycled due to its high cost contribution. One regeneration method that offers certain advantages is the oxidation of NADH......Traditional chemical methods for alcohol oxidation are often associated with issues such as high consumption of expensive oxidizing agents, generation of metal waste and the use of environmentally undesirable organic solvents. Developing green, selective catalysts is therefore important from...... using water forming NADH oxidases (NOX-2). The implementation of the ADH/NOX system for alcohol oxidation, however, requires consideration of several different issues. Enzyme activity and stability at relevant pH and temperature conditions, but also the tolerance to the substrates and products present...

  10. Substrate- and Cofactor-independent Inhibition of Histone Demethylase KDM4C

    DEFF Research Database (Denmark)

    Leurs, Ulrike; Lohse, Brian; Rand, Kasper Dyrberg

    2014-01-01

    Inhibition of histone demethylases has within recent years advanced into a new strategy for treating cancer and other diseases. Targeting specific histone demethylases can be challenging as the active sites of KDM1A-B and KDM-4A-D histone demethylases, respectively, are highly conserved. Most...... inhibitors developed up-to-date target either the cofactor- or substrate-binding sites of these enzymes, resulting in a lack of selectivity and off-target effects. This study describes the discovery of the first peptide-based inhibitors of KDM4 histone demethylases that do not share the histone peptide...... sequence, or inhibit through substrate competition. Through screening of DNA-encoded peptide libraries against KDM1 and -4 histone demethylases by phage display, two cyclic peptides targeting the histone demethylase KDM4C were identified and developed as inhibitors by amino acid replacement, truncation...

  11. Identification and Characterization of the Novel p97 co-factors, Rep8 and ASPL

    DEFF Research Database (Denmark)

    Klausen, Louise Kjær

    to the ER membrane with the UBX domain situated in the cytosol. Mouse Rep8 is highly tissue-specific and abundant in gonads. In tests, Rep8 is expressed in post-meiotic round spermatids, whereas in ovaries Rep8 is expressed in granulosa cells. Additional precipitation experiments revealed that Rep8......The highly conserved and ubiquitin-specific AAA ATPase p97 acts on ubiquitylated substrates in diverse cellular mechanisms such as chromatin-associated degradation, fusion of homotypic membranes and ER-associated degradation. Different p97 cofactors associate with the ATPase, thereby constituting...... that ASPL localizes to the ER membrane and in vitro ASPL leads to disassembly of the p97 hexameric ATPase. Rep8 was found to interact with p97 both in vitro and in vivo, and the binding was mediated through the N-domain of p97 and the UBX domain of Rep8. Localization studies showed that Rep8 localizes...

  12. Income poverty, poverty co-factors, and the adjustment of children in elementary school.

    Science.gov (United States)

    Ackerman, Brian P; Brown, Eleanor D

    2006-01-01

    Since 1990, there have been great advances in how developmental researchers construct poverty. These advances are important because they may help inform social policy at many levels and help frame how American culture constructs poverty for children, both symbolically and in the opportunities children and families get to escape from poverty. Historically, developmental perspectives have embodied social address and main effects models, snapshot views of poverty effects at single points in time, and a rather narrow focus on income as the symbolic marker of the ecology of disadvantage. More recent views, in contrast, emphasize the diverse circumstances of disadvantaged families and diverse outcomes of disadvantaged children, the multiple sources of risk and the multiple determinants of poor outcomes for these children, dynamic aspects of that ecology, and change as well as continuity in outcome trajectories. The advances also consist of more powerful frames for understanding the ecology of disadvantage and the risk it poses for child outcomes. Most developmental researchers still tend to frame causal variables ultimately in terms of the dichotomy between social causation and social selection views, with a primary emphasis on the former. In part, this framing has reflected limitations of sample size and design, because the theoretical and empirical power of reciprocal selection models is clear (Kim et al., 2003). The conceptual advances that prompt such models include widespread acknowledgement of third variable problems in interpreting effects, of the clear need for multivariate approaches, and the need to pursue mechanisms and moderators of the relations between causal candidates and child outcomes. In the context of these advances, one of the core goals of our research program has been to construct robust representations of environmental adversity for disadvantaged families. Most of our research focuses on contextual co-factors at a family level (e.g., maternal

  13. Radical Change by Entrepreneurial Design

    National Research Council Canada - National Science Library

    Roberts, Nancy C

    1998-01-01

    .... Radical change by entrepreneurial design then becomes the focal point, in order to acquaint the reader with the strategies and tactics of well-known entrepreneurs who have been successful in molding...

  14. Penile rehabilitation after radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Ohl, Dana A; Ralph, David

    2013-01-01

    The pathophysiology of erectile dysfunction after radical prostatectomy (RP) is believed to include neuropraxia, which leads to temporarily reduced oxygenation and subsequent structural changes in penile tissue. This results in veno-occlusive dysfunction, therefore, penile rehabilitation programmes...

  15. Rice Bran Metabolome Contains Amino Acids, Vitamins & Cofactors, and Phytochemicals with Medicinal and Nutritional Properties.

    Science.gov (United States)

    Zarei, Iman; Brown, Dustin G; Nealon, Nora Jean; Ryan, Elizabeth P

    2017-12-01

    Rice bran is a functional food that has shown protection against major chronic diseases (e.g. obesity, diabetes, cardiovascular disease and cancer) in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals. Food metabolomics uses multiple chromatography and mass spectrometry platforms to detect and identify a diverse range of small molecules with high sensitivity and precision, and has not been completed for rice bran. This study utilized global, non-targeted metabolomics to identify small molecules in rice bran, and conducted a comprehensive search of peer-reviewed literature to determine bioactive compounds. Three U.S. rice varieties (Calrose, Dixiebelle, and Neptune), that have been used for human dietary intervention trials, were assessed herein for bioactive compounds that have disease control and prevention properties. The profiling of rice bran by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) identified 453 distinct phytochemicals, 209 of which were classified as amino acids, cofactors & vitamins, and secondary metabolites, and were further assessed for bioactivity. A scientific literature search revealed 65 compounds with health properties, 16 of which had not been previously identified in rice bran. This suite of amino acids, cofactors & vitamins, and secondary metabolites comprised 46% of the identified rice bran metabolome, which substantially enhanced our knowledge of health-promoting rice bran compounds provided during dietary supplementation. Rice bran metabolite profiling revealed a suite of biochemical molecules that can be further investigated and exploited for multiple nutritional therapies and medical food applications. These bioactive compounds may also be biomarkers of dietary rice bran intake. The medicinal compounds associated with rice bran can function as a network across metabolic pathways and this

  16. Radical prostatectomy. Results and indications

    International Nuclear Information System (INIS)

    Jacqmin, D.

    1997-01-01

    Radical prostatectomy is the surgical curative treatment of localized prostate cancer. The survival is good in young patients (<70) with T2 N0M0 tumors and more than 10 year's life expectancy. Side-effects are urinary incontinence, impotence and anastomosis stricture. Quality of life should be considered as an important factor for the choice of the patient between radical prostatectomy, radiotherapy and follow-up. (author)

  17. Radical Islamism and Failed Developmentalism

    OpenAIRE

    Rahnema, Saeed

    2008-01-01

    The rise of radical Islamism in recent years does not limit the applicability of the concept of cultural nationalism. Rather the two are intertwined in ways which this article will attempt to highlight. Islam took specific national forms as modern nation-states arose and the contemporary resurgence of radical Islamism also follows that modern pattern. I examine the emergence of the three most important movements in the Islamic world, namely, the Muslim Brotherhood in Egypt, Jama'at-e Islami i...

  18. Laparoscopic radical cystectomy: key points

    Directory of Open Access Journals (Sweden)

    D. V. Perlin

    2018-01-01

    Full Text Available Background. Radical cystectomy remains the golden standard for treatment of muscle invasive bladder cancer. Objective: to duplicate with highest accuracy the open radical cystectomy procedure, which we successfully utilized earlier in our clinic, in the of laparoscopic conditions in order to preserve the advantages of minimally invasive procedures and retain the reliability of the tried and tested open surgery.Materials and methods. In the report were included 35 patients (27 men and 8 women with bladder cancer, who underwent laparoscopic radical cystectomy in Volgograd Regional Center of Urology and Nephrology between April 2013 and March 2016. Only the patients who had been submitted to full intracorporal ileal conduits were included.Results. The mean operative time was 378 minutes, the mean blood loss was 285 millilitres, the mean length of hospital stay was 12.4 days, only 20 % of patients required the narcotic anesthetics. The postoperative complication rate was 11.4 %. However, the majority of the patients were successfully treated with minimally invasive procedures. Generally, our results were similar to other reported studies.Conclusion. Laparoscopic radical cystectomy is a safe and efficient modality of treatment of bladder cancer. However, it needs more procedures and longer observation period to establish laparoscopic radical cystectomy as an alternative to open radical cystectomy.

  19. Protein S binding to human endothelial cells is required for expression of cofactor activity for activated protein C

    NARCIS (Netherlands)

    Hackeng, T. M.; Hessing, M.; van 't Veer, C.; Meijer-Huizinga, F.; Meijers, J. C.; de Groot, P. G.; van Mourik, J. A.; Bouma, B. N.

    1993-01-01

    An important feedback mechanism in blood coagulation is supplied by the protein C/protein S anticoagulant pathway. In this study we demonstrate that the binding of human protein S to cultured human umbilical vein endothelial cells (HUVECs) is required for the expression of cofactor activity of

  20. The games radicals play : special issue on free radicals and radical ions

    OpenAIRE

    Walton, J.C.; Williams, F.

    2015-01-01

    Chemistry and Physics have aptly been described as “most excellent children of Intellect and Art” [1]. Both these “children” engage with many playthings, and molecules rank as one of their first favorites, especially radicals, which are amongst the most lively and exciting. Checking out radicals dancing to the music of entropy round their potential energy ballrooms is surely both entertaining and enlightening. Radicals’ old favorite convolutions are noteworthy, but the new styles, modes and a...

  1. Involvement of the Cys-Tyr cofactor on iron binding in the active site of human cysteine dioxygenase.

    Science.gov (United States)

    Arjune, Sita; Schwarz, Guenter; Belaidi, Abdel A

    2015-01-01

    Sulfur metabolism has gained increasing medical interest over the last years. In particular, cysteine dioxygenase (CDO) has been recognized as a potential marker in oncology due to its altered gene expression in various cancer types. Human CDO is a non-heme iron-dependent enzyme, which catalyzes the irreversible oxidation of cysteine to cysteine sulfinic acid, which is further metabolized to taurine or pyruvate and sulfate. Several studies have reported a unique post-translational modification of human CDO consisting of a cross-link between cysteine 93 and tyrosine 157 (Cys-Tyr), which increases catalytic efficiency in a substrate-dependent manner. However, the reaction mechanism by which the Cys-Tyr cofactor increases catalytic efficiency remains unclear. In this study, steady-state kinetics were determined for wild type CDO and two different variants being either impaired or saturated with the Cys-Tyr cofactor. Cofactor formation in CDO resulted in an approximately fivefold increase in k cat and tenfold increase in k cat/K m over the cofactor-free CDO variant. Furthermore, iron titration experiments revealed an 18-fold decrease in K d of iron upon cross-link formation. This finding suggests a structural role of the Cys-Tyr cofactor in coordinating the ferrous iron in the active site of CDO in accordance with the previously postulated reaction mechanism of human CDO. Finally, we identified product-based inhibition and α-ketoglutarate and glutarate as CDO inhibitors using a simplified well plate-based activity assay. This assay can be used for high-throughput identification of additional inhibitors, which may contribute to understand the functional importance of CDO in sulfur amino acid metabolism and related diseases.

  2. Conversion of alkyl radicals to allyl radicals in irradiated single crystal mats of polyethylene

    International Nuclear Information System (INIS)

    Fujimura, T.; Hayakawa, N.; Kuriyama, I.

    1978-01-01

    The decay of alkyl radicals, the conversion of alkyl radicals to allyl radicals and the trapping of allyl radicals in irradiated single crystal mats of polyethylene have been studied by electron spin resonance (e.s.r.). It has been suggested that in the crystal core alkyl radicals react with trans-vinylene double bonds and are converted into trans-vinylene allyl radicals; at the crystal surface, alkyl radicals react with vinyl end groups and are converted into allyl radicals with vinyl end groups. The decay of radical pairs and the formation of trans-vinylene double bonds are discussed. (author)

  3. 17.9.3 Radical cations of diazo compounds

    Science.gov (United States)

    Davies, A. G.

    This document is part of Subvolume E2 `Phosphorus-Centered Radicals, Radicals Centered on Other Heteroatoms, Organic Radical Ions' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  4. Photoionization of the OH radical

    International Nuclear Information System (INIS)

    Dehmer, P.M.

    1985-01-01

    The hydroxyl radical (OH) is one of the most thoroughly studied free radicals because of its importance in atmospheric chemistry, combustion processes, and the interstellar medium. Detailed experimental and theoretical studies have been performed on the ground electronic state (X 2 PI/sub i/) and on the four lowest bound excited electronic states (A 2 Σ + , B 2 Σ + , D 2 Σ - , and C 2 Σ + ). However, because it is difficult to distinguish the spectrum of OH from the spectra of the various radical precursors, the absorption spectrum in the wavelength region below 1200 A has not been well characterized. In the present work, the spectrum of OH has been determined in the wavelength region from 750 to 950 A using the technique of photoionization mass spectrometry. This technique allows complete separation of the spectrum of OH from that of the other components of the discharge and permits the unambiguous determination of the spectrum of OH

  5. Radical-Mediated Enzymatic Polymerizations

    Science.gov (United States)

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  6. Donor free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E. [15 Way Points Rd., Danville, CA 94526; Wasley, Richard J. [4290 Colgate Way, Livermore, CA 94550

    1980-04-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a donor additive comprising an organic compound or mixture of organic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and which is not an explosive, or an inorganic compound or mixture of inorganic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and selected from ammonium or alkali metal persulfates.

  7. Radical feminists & trans activists truce

    OpenAIRE

    Mackay, F.

    2014-01-01

    #GenderWeek: Truce! When radical feminists and trans feminists empathise\\ud Feminist Times\\ud By Finn Mackay \\ud read all #GenderWeek articles.\\ud We wanted to explore the ground between the polarised, entrenched positions in the so-called “TERF-war”. Radical feminists on one pole, trans-inclusionary feminists and trans activists on the other. The disputed territory being women-only space, language and the ever changing legal framework surrounding gender.\\ud Entrenchment leads to stalemate. S...

  8. Rational modification of Corynebacterium glutamicum dihydrodipicolinate reductase to switch the nucleotide-cofactor specificity for increasing l-lysine production.

    Science.gov (United States)

    Xu, Jian-Zhong; Yang, Han-Kun; Liu, Li-Ming; Wang, Ying-Yu; Zhang, Wei-Guo

    2018-03-25

    l-lysine is an important amino acid in animals and humans and NADPH is a vital cofactor for maximizing the efficiency of l-lysine fermentation. Dihydrodipicolinate reductase (DHDPR), an NAD(P)H-dependent enzyme, shows a variance in nucleotide-cofactor affinity in bacteria. In this study, we rationally engineered Corynebacterium glutamicum DHDPR (CgDHDPR) to switch its nucleotide-cofactor specificity resulting in an increase in final titer (from 82.6 to 117.3 g L -1 ), carbon yield (from 0.35 to 0.44 g [g glucose] -1 ) and productivity (from 2.07 to 2.93 g L -1  hr -1 ) of l-lysine in JL-6 ΔdapB::Ec-dapB C115G,G116C in fed-batch fermentation. To do this, we comparatively analyzed the characteristics of CgDHDPR and Escherichia coli DHDPR (EcDHDPR), indicating that hetero-expression of NADH-dependent EcDHDPR increased l-lysine production. Subsequently, we rationally modified the conserved structure of cofactor-binding motif, and results indicated that introducing the mutation K11A or R13A in CgDHDPR and introducing the mutation R16A or R39A in EcDHDPR modifies the nucleotide-cofactor affinity of DHDPR. Lastly, the effects of these mutated DHDPRs on l-lysine production were investigated. The highest increase (26.2%) in l-lysine production was observed for JL-6 ΔdapB::Ec-dapB C115G,G116C , followed by JL-6 Cg-dapB C37G,G38C (21.4%) and JL-6 ΔdapB::Ec-dapB C46G,G47C (15.2%). This is the first report of a rational modification of DHDPR that enhances the l-lysine production and yield through the modulation of nucleotide-cofactor specificity. © 2018 Wiley Periodicals, Inc.

  9. A novel cofactor-binding mode in bacterial IMP dehydrogenases explains inhibitor selectivity.

    Science.gov (United States)

    Makowska-Grzyska, Magdalena; Kim, Youngchang; Maltseva, Natalia; Osipiuk, Jerzy; Gu, Minyi; Zhang, Minjia; Mandapati, Kavitha; Gollapalli, Deviprasad R; Gorla, Suresh Kumar; Hedstrom, Lizbeth; Joachimiak, Andrzej

    2015-02-27

    The steadily rising frequency of emerging diseases and antibiotic resistance creates an urgent need for new drugs and targets. Inosine 5'-monophosphate dehydrogenase (IMP dehydrogenase or IMPDH) is a promising target for the development of new antimicrobial agents. IMPDH catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD(+), which is the pivotal step in the biosynthesis of guanine nucleotides. Potent inhibitors of bacterial IMPDHs have been identified that bind in a structurally distinct pocket that is absent in eukaryotic IMPDHs. The physiological role of this pocket was not understood. Here, we report the structures of complexes with different classes of inhibitors of Bacillus anthracis, Campylobacter jejuni, and Clostridium perfringens IMPDHs. These structures in combination with inhibition studies provide important insights into the interactions that modulate selectivity and potency. We also present two structures of the Vibrio cholerae IMPDH in complex with IMP/NAD(+) and XMP/NAD(+). In both structures, the cofactor assumes a dramatically different conformation than reported previously for eukaryotic IMPDHs and other dehydrogenases, with the major change observed for the position of the NAD(+) adenosine moiety. More importantly, this new NAD(+)-binding site involves the same pocket that is utilized by the inhibitors. Thus, the bacterial IMPDH-specific NAD(+)-binding mode helps to rationalize the conformation adopted by several classes of prokaryotic IMPDH inhibitors. These findings offer a potential strategy for further ligand optimization. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. A Novel Cofactor-binding Mode in Bacterial IMP Dehydrogenases Explains Inhibitor Selectivity*

    Science.gov (United States)

    Makowska-Grzyska, Magdalena; Kim, Youngchang; Maltseva, Natalia; Osipiuk, Jerzy; Gu, Minyi; Zhang, Minjia; Mandapati, Kavitha; Gollapalli, Deviprasad R.; Gorla, Suresh Kumar; Hedstrom, Lizbeth; Joachimiak, Andrzej

    2015-01-01

    The steadily rising frequency of emerging diseases and antibiotic resistance creates an urgent need for new drugs and targets. Inosine 5′-monophosphate dehydrogenase (IMP dehydrogenase or IMPDH) is a promising target for the development of new antimicrobial agents. IMPDH catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD+, which is the pivotal step in the biosynthesis of guanine nucleotides. Potent inhibitors of bacterial IMPDHs have been identified that bind in a structurally distinct pocket that is absent in eukaryotic IMPDHs. The physiological role of this pocket was not understood. Here, we report the structures of complexes with different classes of inhibitors of Bacillus anthracis, Campylobacter jejuni, and Clostridium perfringens IMPDHs. These structures in combination with inhibition studies provide important insights into the interactions that modulate selectivity and potency. We also present two structures of the Vibrio cholerae IMPDH in complex with IMP/NAD+ and XMP/NAD+. In both structures, the cofactor assumes a dramatically different conformation than reported previously for eukaryotic IMPDHs and other dehydrogenases, with the major change observed for the position of the NAD+ adenosine moiety. More importantly, this new NAD+-binding site involves the same pocket that is utilized by the inhibitors. Thus, the bacterial IMPDH-specific NAD+-binding mode helps to rationalize the conformation adopted by several classes of prokaryotic IMPDH inhibitors. These findings offer a potential strategy for further ligand optimization. PMID:25572472

  11. A peptide of heparin cofactor II inhibits endotoxin-mediated shock and invasive Pseudomonas aeruginosa infection.

    Directory of Open Access Journals (Sweden)

    Martina Kalle

    Full Text Available Sepsis and septic shock remain important medical problems with high mortality rates. Today's treatment is based mainly on using antibiotics to target the bacteria, without addressing the systemic inflammatory response, which is a major contributor to mortality in sepsis. Therefore, novel treatment options are urgently needed to counteract these complex sepsis pathologies. Heparin cofactor II (HCII has recently been shown to be protective against Gram-negative infections. The antimicrobial effects were mapped to helices A and D of the molecule. Here we show that KYE28, a 28 amino acid long peptide representing helix D of HCII, is antimicrobial against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive Bacillus subtilis and Staphylococcus aureus, as well as the fungus Candida albicans. Moreover, KYE28 binds to LPS and thereby reduces LPS-induced pro-inflammatory responses by decreasing NF-κB/AP-1 activation in vitro. In mouse models of LPS-induced shock, KYE28 significantly enhanced survival by dampening the pro-inflammatory cytokine response. Finally, in an invasive Pseudomonas infection model, the peptide inhibited bacterial growth and reduced the pro-inflammatory response, which lead to a significant reduction of mortality. In summary, the peptide KYE28, by simultaneously targeting bacteria and LPS-induced pro-inflammatory responses represents a novel therapeutic candidate for invasive infections.

  12. An antimicrobial helix A-derived peptide of heparin cofactor II blocks endotoxin responses in vivo.

    Science.gov (United States)

    Papareddy, Praveen; Kalle, Martina; Singh, Shalini; Mörgelin, Matthias; Schmidtchen, Artur; Malmsten, Martin

    2014-05-01

    Host defense peptides are key components of the innate immune system, providing multi-facetted responses to invading pathogens. Here, we describe that the peptide GKS26 (GKSRIQRLNILNAKFAFNLYRVLKDQ), corresponding to the A domain of heparin cofactor II (HCII), ameliorates experimental septic shock. The peptide displays antimicrobial effects through direct membrane disruption, also at physiological salt concentration and in the presence of plasma and serum. Biophysical investigations of model lipid membranes showed the antimicrobial action of GKS26 to be mirrored by peptide incorporation into, and disordering of, bacterial lipid membranes. GKS26 furthermore binds extensively to bacterial lipopolysaccharide (LPS), as well as its endotoxic lipid A moiety, and displays potent anti-inflammatory effects, both in vitro and in vivo. Thus, for mice challenged with ip injection of LPS, GKS26 suppresses pro-inflammatory cytokines, reduces vascular leakage and infiltration in lung tissue, and normalizes coagulation. Together, these findings suggest that GKS26 may be of interest for further investigations as therapeutic against severe infections and septic shock. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. A peptide of heparin cofactor II inhibits endotoxin-mediated shock and invasive Pseudomonas aeruginosa infection.

    Science.gov (United States)

    Kalle, Martina; Papareddy, Praveen; Kasetty, Gopinath; van der Plas, Mariena J A; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

    2014-01-01

    Sepsis and septic shock remain important medical problems with high mortality rates. Today's treatment is based mainly on using antibiotics to target the bacteria, without addressing the systemic inflammatory response, which is a major contributor to mortality in sepsis. Therefore, novel treatment options are urgently needed to counteract these complex sepsis pathologies. Heparin cofactor II (HCII) has recently been shown to be protective against Gram-negative infections. The antimicrobial effects were mapped to helices A and D of the molecule. Here we show that KYE28, a 28 amino acid long peptide representing helix D of HCII, is antimicrobial against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, the Gram-positive Bacillus subtilis and Staphylococcus aureus, as well as the fungus Candida albicans. Moreover, KYE28 binds to LPS and thereby reduces LPS-induced pro-inflammatory responses by decreasing NF-κB/AP-1 activation in vitro. In mouse models of LPS-induced shock, KYE28 significantly enhanced survival by dampening the pro-inflammatory cytokine response. Finally, in an invasive Pseudomonas infection model, the peptide inhibited bacterial growth and reduced the pro-inflammatory response, which lead to a significant reduction of mortality. In summary, the peptide KYE28, by simultaneously targeting bacteria and LPS-induced pro-inflammatory responses represents a novel therapeutic candidate for invasive infections.

  14. Metabolic Regulation of Histone Acetyltransferases by Endogenous Acyl-CoA Cofactors.

    Science.gov (United States)

    Montgomery, David C; Sorum, Alexander W; Guasch, Laura; Nicklaus, Marc C; Meier, Jordan L

    2015-08-20

    The finding that chromatin modifications are sensitive to changes in cellular cofactor levels potentially links altered tumor cell metabolism and gene expression. However, the specific enzymes and metabolites that connect these two processes remain obscure. Characterizing these metabolic-epigenetic axes is critical to understanding how metabolism supports signaling in cancer, and developing therapeutic strategies to disrupt this process. Here, we describe a chemical approach to define the metabolic regulation of lysine acetyltransferase (KAT) enzymes. Using a novel chemoproteomic probe, we identify a previously unreported interaction between palmitoyl coenzyme A (palmitoyl-CoA) and KAT enzymes. Further analysis reveals that palmitoyl-CoA is a potent inhibitor of KAT activity and that fatty acyl-CoA precursors reduce cellular histone acetylation levels. These studies implicate fatty acyl-CoAs as endogenous regulators of histone acetylation, and suggest novel strategies for the investigation and metabolic modulation of epigenetic signaling. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. AMOEBA Polarizable Force Field Parameters of the Heme Cofactor in Its Ferrous and Ferric Forms.

    Science.gov (United States)

    Wu, Xiaojing; Clavaguera, Carine; Lagardère, Louis; Piquemal, Jean-Philip; de la Lande, Aurélien

    2018-04-16

    We report the first parameters of the heme redox cofactors for the polarizable AMOEBA force field in both the ferric and ferrous forms. We consider two types of complexes, one with two histidine side chains as axial ligands and one with a histidine and a methionine side chain as ligands. We have derived permanent multipoles from second-order Møller-Plesset perturbation theory (MP2). The sets of parameters have been validated in a first step by comparison of AMOEBA interaction energies of heme and a collection of biologically relevant molecules with MP2 and Density Functional Theory (DFT) calculations. In a second validation step, we consider interaction energies with large aggregates comprising around 80 H 2 O molecules. These calculations are repeated for 30 structures extracted from semiempirical PM7 DM simulations. Very encouraging agreement is found between DFT and the AMOEBA force field, which results from an accurate treatment of electrostatic interactions. We finally report long (10 ns) MD simulations of cytochromes in two redox states with AMOEBA testing both the 2003 and 2014 AMOEBA water models. These simulations have been carried out with the TINKER-HP (High Performance) program. In conclusion, owing to their ubiquity in biology, we think the present work opens a wide array of applications of the polarizable AMOEBA force field on hemeproteins.

  16. Improved Method for the Incorporation of Heme Cofactors into Recombinant Proteins Using Escherichia coli Nissle 1917.

    Science.gov (United States)

    Fiege, Kerstin; Querebillo, Christine Joy; Hildebrandt, Peter; Frankenberg-Dinkel, Nicole

    2018-05-15

    Recombinant production of heme proteins in Escherichia coli is often limited by the availability of heme in the host. Therefore, several methods, including the reconstitution of heme proteins after production but prior to purification or the HPEX system, conferring the ability to take up external heme have been developed and used in the past. Here we describe the use of the apathogenic E. coli strain Nissle 1917 (EcN) as a suitable host for the recombinant production of heme proteins. EcN has an advantage over commonly used lab strains in that it is able to take up heme from the environment through the heme receptor ChuA. Expression of several heme proteins from different prokaryotic sources led to high yield and quantitative incorporation of the cofactor when heme was supplied in the growth medium. Comparative UV-vis and resonance Raman measurements revealed that the method employed has significant influence on heme coordination with the EcN system representing the most native situation. Therefore, the use of EcN as a host for recombinant heme protein production represents an inexpensive and straightforward method to facilitate further investigations of structure and function.

  17. Recruitment of RNA polymerase II cofactor PC4 to DNA damage sites

    Science.gov (United States)

    Mortusewicz, Oliver; Roth, Wera; Li, Na; Cardoso, M. Cristina; Meisterernst, Michael; Leonhardt, Heinrich

    2008-01-01

    The multifunctional nuclear protein positive cofactor 4 (PC4) is involved in various cellular processes including transcription, replication, and chromatin organization. Recently, PC4 has been identified as a suppressor of oxidative mutagenesis in Escherichia coli and Saccharomyces cerevisiae. To investigate a potential role of PC4 in mammalian DNA repair, we used a combination of live cell microscopy, microirradiation, and fluorescence recovery after photobleaching analysis. We found a clear accumulation of endogenous PC4 at DNA damage sites introduced by either chemical agents or laser microirradiation. Using fluorescent fusion proteins and specific mutants, we demonstrated that the rapid recruitment of PC4 to laser-induced DNA damage sites is independent of poly(ADP-ribosyl)ation and γH2AX but depends on its single strand binding capacity. Furthermore, PC4 showed a high turnover at DNA damages sites compared with the repair factors replication protein A and proliferating cell nuclear antigen. We propose that PC4 plays a role in the early response to DNA damage by recognizing single-stranded DNA and may thus initiate or facilitate the subsequent steps of DNA repair. PMID:19047459

  18. The geochemical record of the ancient nitrogen cycle, nitrogen isotopes, and metal cofactors.

    Science.gov (United States)

    Godfrey, Linda V; Glass, Jennifer B

    2011-01-01

    The nitrogen (N) cycle is the only global biogeochemical cycle that is driven by biological functions involving the interaction of many microorganisms. The N cycle has evolved over geological time and its interaction with the oxygen cycle has had profound effects on the evolution and timing of Earth's atmosphere oxygenation (Falkowski and Godfrey, 2008). Almost every enzyme that microorganisms use to manipulate N contains redox-sensitive metals. Bioavailability of these metals has changed through time as a function of varying redox conditions, and likely influenced the biological underpinnings of the N cycle. It is possible to construct a record through geological time using N isotopes and metal concentrations in sediments to determine when the different stages of the N cycle evolved and the role metal availability played in the development of key enzymes. The same techniques are applicable to understanding the operation and changes in the N cycle through geological time. However, N and many of the redox-sensitive metals in some of their oxidation states are mobile and the isotopic composition or distribution can be altered by subsequent processes leading to erroneous conclusions. This chapter reviews the enzymology and metal cofactors of the N cycle and describes proper utilization of methods used to reconstruct evolution of the N cycle through time. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Dual utilization of NADPH and NADH cofactors enhances xylitol production in engineered Saccharomyces cerevisiae.

    Science.gov (United States)

    Jo, Jung-Hyun; Oh, Sun-Young; Lee, Hyeun-Soo; Park, Yong-Cheol; Seo, Jin-Ho

    2015-12-01

    Xylitol, a natural sweetener, can be produced by hydrogenation of xylose in hemicelluloses. In microbial processes, utilization of only NADPH cofactor limited commercialization of xylitol biosynthesis. To overcome this drawback, Saccharomyces cerevisiae D452-2 was engineered to express two types of xylose reductase (XR) with either NADPH-dependence or NADH-preference. Engineered S. cerevisiae DWM expressing both the XRs exhibited higher xylitol productivity than the yeast strain expressing NADPH-dependent XR only (DWW) in both batch and glucose-limited fed-batch cultures. Furthermore, the coexpression of S. cerevisiae ZWF1 and ACS1 genes in the DWM strain increased intracellular concentrations of NADPH and NADH and improved maximum xylitol productivity by 17%, relative to that for the DWM strain. Finally, the optimized fed-batch fermentation of S. cerevisiae DWM-ZWF1-ACS1 resulted in 196.2 g/L xylitol concentration, 4.27 g/L h productivity and almost the theoretical yield. Expression of the two types of XR utilizing both NADPH and NADH is a promising strategy to meet the industrial demands for microbial xylitol production. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Engineering of the glycerol decomposition pathway and cofactor regulation in an industrial yeast improves ethanol production.

    Science.gov (United States)

    Zhang, Liang; Tang, Yan; Guo, Zhongpeng; Shi, Guiyang

    2013-10-01

    Glycerol is a major by-product of industrial ethanol production and its formation consumes up to 4 % of the sugar substrate. This study modified the glycerol decomposition pathway of an industrial strain of Saccharomyces cerevisiae to optimize the consumption of substrate and yield of ethanol. This study is the first to couple glycerol degradation with ethanol formation, to the best of our knowledge. The recombinant strain overexpressing GCY1 and DAK1, encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, in glycerol degradation pathway, exhibited a moderate increase in ethanol yield (2.9 %) and decrease in glycerol yield (24.9 %) compared to the wild type with the initial glucose concentration of 15 % under anaerobic conditions. However, when the mhpF gene, encoding acetylating NAD⁺-dependent acetaldehyde dehydrogenase from Escherichia coli, was co-expressed in the aforementioned recombinant strain, a further increase in ethanol yield by 5.5 % and decrease in glycerol yield by 48 % were observed for the resultant recombinant strain GDMS1 when acetic acid was added into the medium prior to inoculation compared to the wild type. The process outlined in this study which enhances glycerol consumption and cofactor regulation in an industrial yeast is a promising metabolic engineering strategy to increase ethanol production by reducing the formation of glycerol.

  1. Ntdin, a tobacco senescence-associated gene, is involved in molybdenum cofactor biosynthesis.

    Science.gov (United States)

    Yang, Seung Hwan; Berberich, Thomas; Miyazaki, Atsushi; Sano, Hiroshi; Kusano, Tomonobu

    2003-10-01

    To date, dozens of genes have been reported to be up-regulated with senescence in higher plants. Radish din1 and its ortholog sen1 of Arabidopsis are known as such, but their function is not clear yet. Here we have isolated their counterpart cDNA from tobacco and designated it as NTDIN: Its product, Ntdin, a 185 amino acid polypeptide with 56.8% and 54.2% identity to Atsen1 and Rsdin1, respectively, is localized in chloroplasts. Transcripts of Ntdin are induced by sulfate or nitrate but not by phosphate, suggesting its involvement in sulfur and nitrogen metabolism. A database search revealed that Ntdin shows similarity with the C-terminal region of Nicotiana plumbaginifolia Cnx5, which functions in molybdenum cofactor (Moco) biosynthesis. Transgenic tobacco plants with suppressed Ntdin are more tolerant to chlorate, a substrate analog of nitrate reductase, than controls, implying low nitrate reductase activity in the transgenic plants due to a deficiency of Moco. Indeed, enzymatic activities of two molybdoenzymes, nitrate reductase and xanthine dehydrogenase, in transgenic plants are found to be significantly lower than in control plants. Direct measurement of Moco contents reveals that those transgenic plants contain about 5% Moco of those of the control plants. Abscisic acid and indole-3-acidic acid, whose biosynthetic pathways require Moco, up-regulated Ntdin expression. Taken together, it is concluded that Ntdin functions in a certain step in Moco biosynthesis.

  2. DNA-binding protects p53 from interactions with cofactors involved in transcription-independent functions.

    Science.gov (United States)

    Lambrughi, Matteo; De Gioia, Luca; Gervasio, Francesco Luigi; Lindorff-Larsen, Kresten; Nussinov, Ruth; Urani, Chiara; Bruschi, Maurizio; Papaleo, Elena

    2016-11-02

    Binding-induced conformational changes of a protein at regions distant from the binding site may play crucial roles in protein function and regulation. The p53 tumour suppressor is an example of such an allosterically regulated protein. Little is known, however, about how DNA binding can affect distal sites for transcription factors. Furthermore, the molecular details of how a local perturbation is transmitted through a protein structure are generally elusive and occur on timescales hard to explore by simulations. Thus, we employed state-of-the-art enhanced sampling atomistic simulations to unveil DNA-induced effects on p53 structure and dynamics that modulate the recruitment of cofactors and the impact of phosphorylation at Ser215. We show that DNA interaction promotes a conformational change in a region 3 nm away from the DNA binding site. Specifically, binding to DNA increases the population of an occluded minor state at this distal site by more than 4-fold, whereas phosphorylation traps the protein in its major state. In the minor conformation, the interface of p53 that binds biological partners related to p53 transcription-independent functions is not accessible. Significantly, our study reveals a mechanism of DNA-mediated protection of p53 from interactions with partners involved in the p53 transcription-independent signalling. This also suggests that conformational dynamics is tightly related to p53 signalling. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  3. Tubulin cofactor B regulates microtubule densities during microglia transition to the reactive states

    International Nuclear Information System (INIS)

    Fanarraga, M.L.; Villegas, J.C.; Carranza, G.; Castano, R.; Zabala, J.C.

    2009-01-01

    Microglia are highly dynamic cells of the CNS that continuously survey the welfare of the neural parenchyma and play key roles modulating neurogenesis and neuronal cell death. In response to injury or pathogen invasion parenchymal microglia transforms into a more active cell that proliferates, migrates and behaves as a macrophage. The acquisition of these extra skills implicates enormous modifications of the microtubule and actin cytoskeletons. Here we show that tubulin cofactor B (TBCB), which has been found to contribute to various aspects of microtubule dynamics in vivo, is also implicated in microglial cytoskeletal changes. We find that TBCB is upregulated in post-lesion reactive parenchymal microglia/macrophages, in interferon treated BV-2 microglial cells, and in neonate amoeboid microglia where the microtubule densities are remarkably low. Our data demonstrate that upon TBCB downregulation both, after microglia differentiation to the ramified phenotype in vivo and in vitro, or after TBCB gene silencing, microtubule densities are restored in these cells. Taken together these observations support the view that TBCB functions as a microtubule density regulator in microglia during activation, and provide an insight into the understanding of the complex mechanisms controlling microtubule reorganization during microglial transition between the amoeboid, ramified, and reactive phenotypes

  4. Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway.

    Science.gov (United States)

    Lovelock, Sarah L; Lloyd, Richard C; Turner, Nicholas J

    2014-04-25

    Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1 cB elimination mechanism. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Reaction between protein radicals and other biomolecules

    DEFF Research Database (Denmark)

    Østdal, H.; Davies, M.J.; Andersen, Henrik Jørgen

    2002-01-01

    The present study investigates the reactivity of bovine serum albumin (BSA) radicals towards different biomolecules (urate, linoleic acid, and a polypeptide, poly(Glu-Ala-Tyr)). The BSA radical was formed at room temperature through a direct protein-to-protein radical transfer from H(2)O(2....... Subsequent analysis showed a decrease in the concentration of urate upon reaction with the BSA radical, while the BSA radical in the presence of poly(Glu-Ala-Tyr) resulted in increased formation of the characteristic protein oxidation product, dityrosine. Reaction between the BSA radical and a linoleic acid...

  6. Laparoscopically assisted vaginal radical trachelectomy

    International Nuclear Information System (INIS)

    Bielik, T.; Karovic, M.; Trska, R.

    2013-01-01

    Purpose: Radical trachelectomy is a fertility-sparing procedure with the aim to provide adequate oncological safety to patients with cervical cancer while preserving their fertility. The purpose of this study was to retrospectively evaluate, in a series of 3 patients, the feasibility, morbidity, and safety of laparoscopically assisted vaginal radical trachelectomy for early cervical cancer. Patients and Methods: Three non consecutive patients with FIGO stage IA1 and IB1 cervical cancer was evaluated in a period of years 2008 - 2011. The patients underwent a laparoscopic pelvic lymphadenectomy and radical parametrectomy class II procedure according to the Piver classification. The section of vaginal cuff, trachelectomy, permanent cerclage and isthmo-vaginal anastomosis ware realised by vaginal approach. Results: The median operative time, the median blood loss and the mean number of resected pelvic nodes was comparable with published data. Major intraoperative complications did not occur and no patient required a blood transfusion. The median follow-up time was 33 (38-59) months. One vaginal recurrence occurred in 7 months after primary surgery. The patient was underwent a radicalisation procedure and adjuvant oncologic therapy and now is free of disease. Conclusions: Laparoscopically assisted vaginal radical trachelectomy (LAVRT)may be an alternative in fertility-preserving surgery for early cervical cancer. The procedure offers patients potential benefits of minimally invasive surgery with adequate oncological safety, but it should be reserved for oncologic surgeons trained in advanced laparoscopic procedures. (author)

  7. Is Radical Innovation Management Misunderstood?

    DEFF Research Database (Denmark)

    Kristiansen, Jimmi Normann; Gertsen, Frank

    2015-01-01

    This paper poses a critical view on radical innovation (RI) management research and practice. The study investigates how expected RI performance influences firms’ under- standing of their RI capability. RI performance is often based on output measures such as market shares or fiscal return...

  8. Exploring the Theories of Radicalization

    Directory of Open Access Journals (Sweden)

    Maskaliūnaitė Asta

    2015-12-01

    Full Text Available After the London bombings in July 2005, the concern of terrorism scholars and policy makers has turned to “home-grown” terrorism and potential for political violence from within the states. “Radicalization” became a new buzz word. This article follows a number of reviews of the literature on radicalization and offers another angle for looking at this research. First, it discusses the term “radicalization” and suggests the use of the following definition of radicalization as a process by which a person adopts belief systems which justify the use of violence to effect social change and comes to actively support as well as employ violent means for political purposes. Next, it proposes to see the theories of radicalization focusing on the individual and the two dimensions of his/her motivation: whether that motivation is internal or external and whether it is due to personal choice or either internal (due to some psychological traits or external compulsion. Though not all theories fall neatly within these categories, they make it possible to make comparisons of contributions from a variety of different areas thus reflecting on the interdisciplinary nature of the study of terrorism in general and radicalization as a part of it.

  9. Ultrasound-induced radical polymerization

    NARCIS (Netherlands)

    Kuijpers, M.W.A.; Kemmere, M.F.; Keurentjes, J.T.F.

    2004-01-01

    Sonochemistry comprises all chemical effects that are induced by ultrasound. Most of these effects are caused by cavitations, ie, the collapse of microscopic bubbles in a liquid. The chemical effects of ultrasound include the formation of radicals and the enhancement of reaction rates at ambient

  10. Erectile function after radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Frey, Anders; Jakobsen, Henrik

    2016-01-01

    collected database and a cross-sectional, questionnaire-based study in patients following radical prostatectomy. Erectile function was assessed with the IIEF-5 and the question "Is your erectile function as good as before the surgery (yes/no)". Patients were included if they were sexually active before...

  11. Panning for SNuRMs: using cofactor profiling for the rational discovery of selective nuclear receptor modulators.

    Science.gov (United States)

    Kremoser, Claus; Albers, Michael; Burris, Thomas P; Deuschle, Ulrich; Koegl, Manfred

    2007-10-01

    Drugs that target nuclear receptors are clinically, as well as commercially, successful. Their widespread use, however, is limited by an inherent propensity of nuclear receptors to trigger beneficial, as well as adverse, pharmacological effects upon drug activation. Hence, selective drugs that display reduced adverse effects, such as the selective estrogen receptor modulator (SERM) Raloxifene, have been developed by guidance through classical cell culture assays and animal trials. Full agonist and selective modulator nuclear receptor drugs, in general, differ by their ability to recruit certain cofactors to the receptor protein. Hence, systematic cofactor profiling is advancing into an approach for the rationally guided identification of selective NR modulators (SNuRMs) with improved therapeutic ratio.

  12. Biocatalytic hydroxylation of n-butane with in situ cofactor regeneration at low temperature and under normal pressure

    Directory of Open Access Journals (Sweden)

    Svenja Staudt

    2012-02-01

    Full Text Available The hydroxylation of n-alkanes, which proceeds in the presence of a P450-monooxygenase advantageously at temperatures significantly below room temperature, is described. In addition, an enzymatic hydroxylation of the “liquid gas” n-butane with in situ cofactor regeneration, which does not require high-pressure conditions, was developed. The resulting 2-butanol was obtained as the only regioisomer, at a product concentration of 0.16 g/L.

  13. Elucidation of new condition-dependent roles for fructose-1,6-bisphosphatase linked to cofactor balances.

    Directory of Open Access Journals (Sweden)

    Du Toit W P Schabort

    Full Text Available The cofactor balances in metabolism is of paramount importance in the design of a metabolic engineering strategy and understanding the regulation of metabolism in general. ATP, NAD+ and NADP+ balances are central players linking the various fluxes in central metabolism as well as biomass formation. NADP+ is especially important in the metabolic engineering of yeasts for xylose fermentation, since NADPH is required by most yeasts in the initial step of xylose utilisation, including the fast-growing Kluyveromyces marxianus. In this simulation study of yeast metabolism, the complex interplay between these cofactors was investigated; in particular, how they may affect the possible roles of fructose-1,6-bisphosphatase, the pentose phosphate pathway, glycerol production and the pyruvate dehydrogenase bypass. Using flux balance analysis, it was found that the potential role of fructose-1,6-bisphosphatase was highly dependent on the cofactor specificity of the oxidative pentose phosphate pathway and on the carbon source. Additionally, the excessive production of ATP under certain conditions might be involved in some of the phenomena observed, which may have been overlooked to date. Based on these findings, a strategy is proposed for the metabolic engineering of a future xylose-fermenting yeast for biofuel production.

  14. O-, N-Atoms-Coordinated Mn Cofactors within a Graphene Framework as Bioinspired Oxygen Reduction Reaction Electrocatalysts.

    Science.gov (United States)

    Yang, Yang; Mao, Kaitian; Gao, Shiqi; Huang, Hao; Xia, Guoliang; Lin, Zhiyu; Jiang, Peng; Wang, Changlai; Wang, Hui; Chen, Qianwang

    2018-05-28

    Manganese (Mn) is generally regarded as not being sufficiently active for the oxygen reduction reaction (ORR) compared to other transition metals such as Fe and Co. However, in biology, manganese-containing enzymes can catalyze oxygen-evolving reactions efficiently with a relative low onset potential. Here, atomically dispersed O and N atoms coordinated Mn active sites are incorporated within graphene frameworks to emulate both the structure and function of Mn cofactors in heme-copper oxidases superfamily. Unlike previous single-metal catalysts with general M-N-C structures, here, it is proved that a coordinated O atom can also play a significant role in tuning the intrinsic catalytic activities of transition metals. The biomimetic electrocatalyst exhibits superior performance for the ORR and zinc-air batteries under alkaline conditions, which is even better than that of commercial Pt/C. The excellent performance can be ascribed to the abundant atomically dispersed Mn cofactors in the graphene frameworks, confirmed by various characterization methods. Theoretical calculations reveal that the intrinsic catalytic activity of metal Mn can be significantly improved via changing local geometry of nearest coordinated O and N atoms. Especially, graphene frameworks containing the Mn-N 3 O 1 cofactor demonstrate the fastest ORR kinetics due to the tuning of the d electronic states to a reasonable state. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Absorption and emission spectroscopic characterization of BLUF protein Slr1694 from Synechocystis sp. PCC6803 with roseoflavin cofactor.

    Science.gov (United States)

    Zirak, P; Penzkofer, A; Mathes, T; Hegemann, P

    2009-11-09

    The wild-type BLUF protein Slr1694 from Synechocystis sp. PCC6803 (BLUF=blue-light sensor using FAD) has flavin adenosine dinucleotide (FAD) as natural cofactor. This light sensor causes positive phototaxis of the marine cyanobacterium. In this study the FAD cofactor of the wild-type Slr1694 was replaced by roseoflavin (RoF) and the roseoflavin derivatives RoFMN and RoFAD during heterologous expression in a riboflavin auxotrophic E. coli strain. An absorption and emission spectroscopic characterization of the cofactor-exchanged-Slr1694 (RoSlr) was carried out both under dark conditions and under illuminated conditions. The behaviour of RoF embedded in RoSlr in aqueous solution at pH 8 is compared with the behaviour of RoF in aqueous solution. The fluorescence of RoF and RoSlr is quenched by photo-induced twisted intra-molecular charge transfer at room temperature with stronger effect for RoF. The fluorescence quenching is diminished at liquid nitrogen temperature. Light exposure of RoSlr causes irreversible conversion of the protein embedded roseoflavins to 8-methylamino-flavins, 8-dimethylamino-lumichrome and 8-methylamino-lumichrome.

  16. Catalase in peroxidase clothing: Interdependent cooperation of two cofactors in the catalytic versatility of KatG.

    Science.gov (United States)

    Njuma, Olive J; Ndontsa, Elizabeth N; Goodwin, Douglas C

    2014-02-15

    Catalase-peroxidase (KatG) is found in eubacteria, archaea, and lower eukaryotae. The enzyme from Mycobacterium tuberculosis has received the greatest attention because of its role in activation of the antitubercular pro-drug isoniazid, and the high frequency with which drug resistance stems from mutations to the katG gene. Generally, the catalase activity of KatGs is striking. It rivals that of typical catalases, enzymes with which KatGs share no structural similarity. Instead, catalatic turnover is accomplished with an active site that bears a strong resemblance to a typical peroxidase (e.g., cytochrome c peroxidase). Yet, KatG is the only member of its superfamily with such capability. It does so using two mutually dependent cofactors: a heme and an entirely unique Met-Tyr-Trp (MYW) covalent adduct. Heme is required to generate the MYW cofactor. The MYW cofactor allows KatG to leverage heme intermediates toward a unique mechanism for H2O2 oxidation. This review evaluates the range of intermediates identified and their connection to the diverse catalytic processes KatG facilitates, including mechanisms of isoniazid activation. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Flavonoids as scavengers of nitric oxide radical.

    NARCIS (Netherlands)

    van Acker, S.A.B.E.; Tromp, M.N.J.L.; Haenen, G.R.M.M.; van der Vijgh, W.J.F.; Bast, A.

    1995-01-01

    Flavonoids are a group of naturally occurring compounds used, e.g., in the treatment of vascular endothelial damage. They are known to be excellent scavengers of oxygen free radicals. Since the nitric oxide radical (

  18. O conceito de mal radical The concept of radical evil

    Directory of Open Access Journals (Sweden)

    Adriano Correia

    2005-01-01

    Full Text Available A noção de mal radical aparece em Kant no contexto da discussão da religião nos limites da simples razão e busca dar conta da complexa relação entre o respeito pela lei moral e o amor-próprio na definição do móbil para a ação. Na busca por identificar o fundamento da propensão para o mal no homem, Kant se vê diante da dificuldade de ter de articular natureza e liberdade, e ainda que a noção de mal radical possa conservar algumas ambigüidades, permite conceber uma noção de responsabilidade compatível com uma inata propensão para o mal. Neste texto busco explicitar alguns passos fundamentais na construção do conceito por Kant.The concept of radical evil appears in Kant's theory when he discusses the religion in the limits of the mere reason and aims explain the complex relationship between respect for the moral law and the self-love, for establish the motive of the action. By aiming identify the basis of human inclination to evil, Kant is faced with the trouble of have to put nature and freedom in connection. Despite of the concept of radical evil retain some ambiguity, it allows conceive a notion of responsibility suitable to an inherent inclination to evil. In this paper is my purpose to explain some basic moments of Kantian formulation of that notion.

  19. Free radicals in chemical carcinogenesis.

    Science.gov (United States)

    Clemens, M R

    1991-12-15

    During the past decade, remarkable progress has been made in our understanding of cancer-causing agents, mechanisms of cancer formation and the behavior of cancer cells. Cancer is characterized primarily by an increase in the number of abnormal cells derived from a given normal tissue, invasion of adjacent tissues by these abnormal cells, and lymphatic or blood-borne spread of malignant cells to regional lymph nodes and to distant sites (metastasis). It has been estimated that about 75-80% of all human cancers are environmentally induced, 30-40% of them by diet. Only a small minority, possibly no more than 2% of all cases, result purely from inherent genetic changes. Several lines of evidence confirm that the fundamental molecular event or events that cause a cell to become malignant occur at the level of the DNA and a variety of studies indicate that the critical molecular event in chemical carcinogenesis is the interaction of the chemical agent with DNA. The demonstration that DNA isolated from tumor cells can transfect normal cells and render them neoplastic provides direct proof that an alteration of the DNA is responsible for cancer. The transforming genes, or oncogenes, have been identified by restriction endonuclease mapping. One of the characteristics of tumor cells generated by transformation with viruses, chemicals, or radiation is their reduced requirement for serum growth factors. A critical significance of electrophilic metabolites of carcinogenes in chemical carcinogenesis has been demonstrated. A number of "proximate" and "ultimate" metabolites, especially those of aromatic amines, were described. The "ultimate" forms of carcinogens actually interact with cellular constituents to cause neoplastic transformation and are the final metabolic products in most pathways. Recent evidence indicates that free radical derivatives of chemical carcinogens may be produced both metabolically and nonenzymatically during their metabolism. Free radicals carry no

  20. Muonium radicals in benzene-styrene mixtures

    International Nuclear Information System (INIS)

    Ng, B.W.; Stadlbauer, J.W.; Walker, D.C.

    1984-01-01

    Muonium radicals were observed through their μ + SR precession frequencies in high transverse magnetic fields in pure benzene, pure styrene and their mixtures, all as liquids at room temperature. In benzene-styrene mixtures, the radicals obtained in each pure liquid are both present, so no slow (10 -9 -10 -5 s) intermolecular exchange occurs; but strong selectivity was found with the formation of the radical from styrene being about eight-times more probable than the radical from benzene. (Auth.)

  1. Aspergillus fumigatus SidA is a highly specific ornithine hydroxylase with bound flavin cofactor.

    Science.gov (United States)

    Chocklett, Samuel W; Sobrado, Pablo

    2010-08-10

    Ferrichrome is a hydroxamate-containing siderophore produced by the pathogenic fungus Aspergillus fumigatus under iron-limiting conditions. This siderophore contains N(5)-hydroxylated l-ornithines essential for iron binding. A. fumigatus siderophore A (Af SidA) catalyzes the flavin- and NADPH-dependent hydroxylation of l-ornithine in ferrichrome biosynthesis. Af SidA was recombinantly expressed and purified as a soluble tetramer and is the first member of this class of flavin monooxygenases to be isolated with a bound flavin cofactor. The enzyme showed typical saturation kinetics with respect to l-ornithine while substrate inhibition was observed at high concentrations of NADPH and NADH. Increasing amounts of hydrogen peroxide were measured as a function of reduced nicotinamide coenzyme concentration, indicating that inhibition was caused by increased uncoupling. Af SidA is highly specific for its amino acid substrate, only hydroxylating l-ornithine. An 8-fold preference in the catalytic efficiency was determined for NADPH compared to NADH. In the absence of substrate, Af SidA can be reduced by NADPH, and a C4a-(hydro)peroxyflavin intermediate is observed. The decay of this intermediate is accelerated by l-ornithine binding. This intermediate was only stabilized by NADPH and not by NADH, suggesting a role for NADP(+) in the stabilization of intermediates in the reaction of Af SidA. NADP(+) is a competitive inhibitor with respect to NADPH, demonstrating that Af SidA forms a ternary complex with NADP(+) and l-ornithine during catalysis. The data suggest that Af SidA likely proceeds by a sequential kinetic mechanism.

  2. Importance of lipopolysaccharide aggregate disruption for the anti-endotoxic effects of heparin cofactor II peptides.

    Science.gov (United States)

    Singh, Shalini; Papareddy, Praveen; Kalle, Martina; Schmidtchen, Artur; Malmsten, Martin

    2013-11-01

    Lipid membrane and lipopolysaccharide (LPS) interactions were investigated for a series of amphiphilic and cationic peptides derived from human heparin cofactor II (HCII), using dual polarization interferometry, ellipsometry, circular dichroism (CD), cryoTEM, and z-potential measurements. Antimicrobial effects of these peptides were compared to their ability to disorder bacterial lipid membranes, while their capacity to block endotoxic effects of LPS was correlated to the binding of these peptides to LPS and its lipid A moiety, and to charge, secondary structure, and morphology of peptide/LPS complexes. While the peptide KYE28 (KYEITTIHNLFRKLTHRLFRRNFGYTLR) displayed potent antimicrobial and anti-endotoxic effects, its truncated variants KYE21 (KYEITTIHNLFRKLTHRLFRR) and NLF20 (NLFRKLTHRLFRRNFGYTLR) provide some clues on structure-activity relations, since KYE21 retains both the antimicrobial and anti-endotoxic effects of KYE28 (although both attenuated), while NLF20 retains the antimicrobial but only a fraction of the anti-endotoxic effect, hence locating the anti-endotoxic effects of KYE28 to its N-terminus. The antimicrobial effect, on the other hand, is primarily located at the C-terminus of KYE28. While displaying quite different endotoxic effects, these peptides bind to a similar extent to both LPS and lipid A, and also induce comparable LPS scavenging on model eukaryotic membranes. In contrast, fragmentation and densification of LPS aggregates, in turn dependent on the secondary structure in the peptide/LPS aggregates, correlate to the anti-endotoxic effect of these peptides, thus identifying peptide-induced packing transitions in LPS aggregates as key for anti-endotoxic functionality. This aspect therefore needs to be taken into account in the development of novel anti-endotoxic peptide therapeutics. Copyright © 2013. Published by Elsevier B.V.

  3. Metal cofactor modulated folding and target recognition of HIV-1 NCp7.

    Science.gov (United States)

    Ren, Weitong; Ji, Dongqing; Xu, Xiulian

    2018-01-01

    The HIV-1 nucleocapsid 7 (NCp7) plays crucial roles in multiple stages of HIV-1 life cycle, and its biological functions rely on the binding of zinc ions. Understanding the molecular mechanism of how the zinc ions modulate the conformational dynamics and functions of the NCp7 is essential for the drug development and HIV-1 treatment. In this work, using a structure-based coarse-grained model, we studied the effects of zinc cofactors on the folding and target RNA(SL3) recognition of the NCp7 by molecular dynamics simulations. After reproducing some key properties of the zinc binding and folding of the NCp7 observed in previous experiments, our simulations revealed several interesting features in the metal ion modulated folding and target recognition. Firstly, we showed that the zinc binding makes the folding transition states of the two zinc fingers less structured, which is in line with the Hammond effect observed typically in mutation, temperature or denaturant induced perturbations to protein structure and stability. Secondly, We showed that there exists mutual interplay between the zinc ion binding and NCp7-target recognition. Binding of zinc ions enhances the affinity between the NCp7 and the target RNA, whereas the formation of the NCp7-RNA complex reshapes the intrinsic energy landscape of the NCp7 and increases the stability and zinc affinity of the two zinc fingers. Thirdly, by characterizing the effects of salt concentrations on the target RNA recognition, we showed that the NCp7 achieves optimal balance between the affinity and binding kinetics near the physiologically relevant salt concentrations. In addition, the effects of zinc binding on the inter-domain conformational flexibility and folding cooperativity of the NCp7 were also discussed.

  4. Dual functionality of β-tryptase protomers as both proteases and cofactors in the active tetramer.

    Science.gov (United States)

    Maun, Henry R; Liu, Peter S; Franke, Yvonne; Eigenbrot, Charles; Forrest, William F; Schwartz, Lawrence B; Lazarus, Robert A

    2018-04-16

    Human β-tryptase, a tetrameric trypsin-like serine protease, is an important mediator of the allergic inflammatory responses in asthma. During acute hypersensitivity reactions, mast cells degranulate, releasing active tetramer as a complex with proteoglycans. Extensive efforts have focused on developing therapeutic β-tryptase inhibitors, but its unique activation mechanism is less well explored. Tryptase is active only after proteolytic removal of the pro-domain followed by tetramer formation via two distinct symmetry-related interfaces. We show that the cleaved I16G mutant cannot tetramerize, likely due to impaired insertion of its N-terminus into its 'activation pocket', indicating allosteric linkage at multiple sites on each protomer. We engineered cysteines into each of the two distinct interfaces (Y75C for small or I99C for large) to assess the activity of each tetramer and disulfide-locked dimer. Using size-exclusion chromatography and enzymatic assays, we demonstrate that the two large tetramer interfaces regulate enzymatic activity, elucidating the importance of this protein-protein interaction for allosteric regulation. Notably, the I99C large interface dimer is active, even in the absence of heparin. We show that a monomeric β-tryptase mutant (I99C*:Y75A:Y37bA where C* is cysteinylated Cys99) cannot form a dimer or tetramer, yet is active, but only in the presence of heparin. Thus heparin both stabilizes the tetramer and allosterically conditions the active site. We hypothesize that each β-tryptase protomer in the tetramer has two distinct roles, acting both as a protease and as a cofactor for its neighboring protomer, to allosterically regulate enzymatic activity, providing a rationale for direct correlation of tetramer stability with proteolytic activity. Copyright © 2018, The American Society for Biochemistry and Molecular Biology.

  5. Metal cofactor modulated folding and target recognition of HIV-1 NCp7.

    Directory of Open Access Journals (Sweden)

    Weitong Ren

    Full Text Available The HIV-1 nucleocapsid 7 (NCp7 plays crucial roles in multiple stages of HIV-1 life cycle, and its biological functions rely on the binding of zinc ions. Understanding the molecular mechanism of how the zinc ions modulate the conformational dynamics and functions of the NCp7 is essential for the drug development and HIV-1 treatment. In this work, using a structure-based coarse-grained model, we studied the effects of zinc cofactors on the folding and target RNA(SL3 recognition of the NCp7 by molecular dynamics simulations. After reproducing some key properties of the zinc binding and folding of the NCp7 observed in previous experiments, our simulations revealed several interesting features in the metal ion modulated folding and target recognition. Firstly, we showed that the zinc binding makes the folding transition states of the two zinc fingers less structured, which is in line with the Hammond effect observed typically in mutation, temperature or denaturant induced perturbations to protein structure and stability. Secondly, We showed that there exists mutual interplay between the zinc ion binding and NCp7-target recognition. Binding of zinc ions enhances the affinity between the NCp7 and the target RNA, whereas the formation of the NCp7-RNA complex reshapes the intrinsic energy landscape of the NCp7 and increases the stability and zinc affinity of the two zinc fingers. Thirdly, by characterizing the effects of salt concentrations on the target RNA recognition, we showed that the NCp7 achieves optimal balance between the affinity and binding kinetics near the physiologically relevant salt concentrations. In addition, the effects of zinc binding on the inter-domain conformational flexibility and folding cooperativity of the NCp7 were also discussed.

  6. Horizontal acquisition of a hypoxia-responsive molybdenum cofactor biosynthesis pathway contributed to Mycobacterium tuberculosis pathoadaptation.

    Science.gov (United States)

    Levillain, Florence; Poquet, Yannick; Mallet, Ludovic; Mazères, Serge; Marceau, Michael; Brosch, Roland; Bange, Franz-Christoph; Supply, Philip; Magalon, Axel; Neyrolles, Olivier

    2017-11-01

    The unique ability of the tuberculosis (TB) bacillus, Mycobacterium tuberculosis, to persist for long periods of time in lung hypoxic lesions chiefly contributes to the global burden of latent TB. We and others previously reported that the M. tuberculosis ancestor underwent massive episodes of horizontal gene transfer (HGT), mostly from environmental species. Here, we sought to explore whether such ancient HGT played a part in M. tuberculosis evolution towards pathogenicity. We were interested by a HGT-acquired M. tuberculosis-specific gene set, namely moaA1-D1, which is involved in the biosynthesis of the molybdenum cofactor. Horizontal acquisition of this gene set was striking because homologues of these moa genes are present all across the Mycobacterium genus, including in M. tuberculosis. Here, we discovered that, unlike their paralogues, the moaA1-D1 genes are strongly induced under hypoxia. In vitro, a M. tuberculosis moaA1-D1-null mutant has an impaired ability to respire nitrate, to enter dormancy and to survive in oxygen-limiting conditions. Conversely, heterologous expression of moaA1-D1 in the phylogenetically closest non-TB mycobacterium, Mycobacterium kansasii, which lacks these genes, improves its capacity to respire nitrate and grants it with a marked ability to survive oxygen depletion. In vivo, the M. tuberculosis moaA1-D1-null mutant shows impaired survival in hypoxic granulomas in C3HeB/FeJ mice, but not in normoxic lesions in C57BL/6 animals. Collectively, our results identify a novel pathway required for M. tuberculosis resistance to host-imposed stress, namely hypoxia, and provide evidence that ancient HGT bolstered M. tuberculosis evolution from an environmental species towards a pervasive human-adapted pathogen.

  7. The Antioxidant Cofactor Alpha-Lipoic Acid May Control Endogenous Formaldehyde Metabolism in Mammals

    Directory of Open Access Journals (Sweden)

    Anastasia V. Shindyapina

    2017-12-01

    Full Text Available The healthy human body contains small amounts of metabolic formaldehyde (FA that mainly results from methanol oxidation by pectin methylesterase, which is active in a vegetable diet and in the gastrointestinal microbiome. With age, the ability to maintain a low level of FA decreases, which increases the risk of Alzheimer's disease and dementia. It has been shown that 1,2-dithiolane-3-pentanoic acid or alpha lipoic acid (ALA, a naturally occurring dithiol and antioxidant cofactor of mitochondrial α-ketoacid dehydrogenases, increases glutathione (GSH content and FA metabolism by mitochondrial aldehyde dehydrogenase 2 (ALDH2 thus manifests a therapeutic potential beyond its antioxidant property. We suggested that ALA can contribute to a decrease in the FA content of mammals by acting on ALDH2 expression. To test this assumption, we administered ALA in mice in order to examine the effect on FA metabolism and collected blood samples for the measurement of FA. Our data revealed that ALA efficiently eliminated FA in mice. Without affecting the specific activity of FA-metabolizing enzymes (ADH1, ALDH2, and ADH5, ALA increased the GSH content in the brain and up-regulated the expression of the FA-metabolizing ALDH2 gene in the brain, particularly in the hippocampus, but did not impact its expression in the liver in vivo or in rat liver isolated from the rest of the body. After ALA administration in mice and in accordance with the increased content of brain ALDH2 mRNA, we detected increased ALDH2 activity in brain homogenates. We hypothesized that the beneficial effects of ALA on patients with Alzheimer's disease may be associated with accelerated ALDH2-mediated FA detoxification and clearance.

  8. Free radicals in health and disease

    International Nuclear Information System (INIS)

    Gonet, B.

    1993-01-01

    Free radicals appear in the cells as the result of exogenic factors (ionizing radiation, UV) or reactions naturally occurring in the cell. Free radical reactions may cause destruction of macromolecules (DNA, lipids, proteins). Free radical pathology is important in many diseases and aging processes in organisms

  9. Oxygen free radicals in rheumatoid arthritis

    NARCIS (Netherlands)

    P. Biemond (Pieter)

    1986-01-01

    textabstractCurrent knowledge strongly suggests that oxygen free radicals are involved in the pathogenesis of RA. Additional information about the mechanism of free radical attack is necessary in order to find out if interaction with the mechanism of free radical damage can be used in the treatment

  10. Radical carbonylations using a continuous microflow system

    Directory of Open Access Journals (Sweden)

    Takahide Fukuyama

    2009-07-01

    Full Text Available Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

  11. A muoniated radical in selenium

    International Nuclear Information System (INIS)

    Reid, I.D.; Cox, S.F.J.; Jayasooriya, U.A.; Zimmermann, U.

    2003-01-01

    We report new 0.3 T transverse-field μSR experiments in crystalline Se which show only a small, slowly relaxing muon signal at 300 K, accounting for about 30% of the incoming muon polarization. However, at 90 K signals are observed around 74 and 157 MHz, characteristic of a radical with a hyperfine coupling of 231 MHz. Very fast relaxation which increases with temperature makes these signals impossible to follow beyond 200 K. Above 400 K a quickly relaxing diamagnetic signal becomes visible, its relaxation falling with increasing temperature. In the melt (>490 K) just a single non-relaxing diamagnetic signal is seen. These observations may be explained by electron spin-exchange with a muoniated radical

  12. DNA Binding Hydroxyl Radical Probes

    OpenAIRE

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2012-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different c...

  13. Anatomical landmarks of radical prostatecomy.

    Science.gov (United States)

    Stolzenburg, Jens-Uwe; Schwalenberg, Thilo; Horn, Lars-Christian; Neuhaus, Jochen; Constantinides, Costantinos; Liatsikos, Evangelos N

    2007-03-01

    In the present study, we review current literature and based on our experience, we present the anatomical landmarks of open and laparoscopic/endoscopic radical prostatectomy. A thorough literature search was performed with the Medline database on the anatomy and the nomenclature of the structures surrounding the prostate gland. The correct handling of puboprostatic ligaments, external urethral sphincter, prostatic fascias and neurovascular bundle is necessary for avoiding malfunction of the urogenital system after radical prostatectomy. When evaluating new prostatectomy techniques, we should always take into account both clinical and final oncological outcomes. The present review adds further knowledge to the existing "postprostatectomy anatomical hazard" debate. It emphasizes upon the role of the puboprostatic ligaments and the course of the external urethral sphincter for urinary continence. When performing an intrafascial nerve sparing prostatectomy most urologists tend to approach as close to the prostatic capsula as possible, even though there is no concurrence regarding the nomenclature of the surrounding fascias and the course of the actual neurovascular bundles. After completion of an intrafascial technique the specimen does not contain any periprostatic tissue and thus the detection of pT3a disease is not feasible. This especially becomes problematic if the tumour reaches the resection margin. Nerve sparing open and laparoscopic radical prostatectomy should aim in maintaining sexual function, recuperating early continence after surgery, without hindering the final oncological outcome to the procedure. Despite the different approaches for radical prostatectomy the key for better results is the understanding of the anatomy of the bladder neck and the urethra.

  14. Radical Smiles Rearrangement: An Update

    Directory of Open Access Journals (Sweden)

    Ingrid Allart-Simon

    2016-07-01

    Full Text Available Over the decades the Smiles rearrangement and its variants have become essential synthetic tools in modern synthetic organic chemistry. In this mini-review we summarized some very recent results of the radical version of these rearrangements. The selected examples illustrate the synthetic power of this approach, especially if it is incorporated into a domino process, for the preparation of polyfunctionalized complex molecules.

  15. Free radical reactions of daunorubicin

    International Nuclear Information System (INIS)

    Houee-Levin, C.

    1991-01-01

    Daunorubicin is an antitumor antibiotic activated in vivo by reduction. Its mechanism of action involves DNA and topoisomerase attack, but side effects are cytotoxicity related to free radical formation. Therefore the mechanism of the one-electron reduction of the drug and the reactions of the daunorubicin transients towards compounds of biological interest have been studied by the methods of radiolysis, in order to provide possible explanations of the drug mechanism of action. Their relative importance in cellular conditions is discussed [fr

  16. Geoscientists and the Radical Middle

    Science.gov (United States)

    Tinker, S. W.

    2015-12-01

    Addressing the great challenges facing society requires industry, government, and academia to work together. I call this overlap space, where compromises are made and real solutions determined, the Radical Middle. Radical because it can appear at times as if the loudest and most publicly influential voices lie outside of the actual solution space, content to provoke but not problem-solve. One key area where geoscientists can play a lead role in the Radical Middle is in the overlap between energy, the environment, and the economy. Globally, fossil fuels still represent 85% of the aggregate energy mix. As existing conventional oil and natural-gas reservoir production continues to slowly decline, unconventional reservoirs, led today by shale and other more expensive resources, will represent a growing part of the oil and gas production mix. Many of these unconventional reservoirs require hydraulic fracturing. The positive economic impact of hydraulic fracturing and associated natural gas and oil production on the United States economy is well documented and undeniable. Yet there are environmental concerns about fracking, and some states and nations have imposed moratoria. This energy-environment-economy space is ideal for leadership from the geosciences. Another such overlap space is the potential for geoscience leadership in relations with China, whose economy and global presence continue to expand. Although China is building major hydropower and natural-gas power plants, as well as nuclear reactors, coal is still king—with the associated environmental impacts. Carbon sequestration—onshore in brine and to enhance oil recovery, as well as offshore—could prove viable. It is vital that educated and objective geoscientists from industry, government, and academia leave their corners and work together in the Radical Middle to educate the public and develop and deliver balanced, economically sensible energy and environmental strategies.

  17. EPR spin trapping of protein radicals

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan; Hawkins, Clare Louise

    2004-01-01

    Electron paramagnetic resonance (EPR) spin trapping was originally developed to aid the detection of low-molecular-mass radicals formed in chemical systems. It has subsequently found widespread use in biology and medicine for the direct detection of radical species formed during oxidative stress...... tumbling radicals are often broad and relatively poor in distinctive features, a number of techniques have been developed that allow a wealth of information to be obtained about the nature, site, and reactions of such radicals. This article summarizes recent developments in this area and reviews selected...... examples of radical formation on proteins....

  18. A paradigm shift for radical SAM reactions: The organometallic intermediate Ω is central to catalysis.

    Science.gov (United States)

    Byer, Amanda S; Yang, Hao; McDaniel, Elizabeth C; Kathiresan, Venkatesan; Impano, Stella; Pagnier, Adrien; Watts, Hope; Denler, Carly; Vagstad, Anna; Piel, Jörn; Duschene, Kaitlin S; Shepard, Eric M; Shields, Thomas P; Scott, Lincoln G; Lilla, Edward A; Yokoyama, Kenichi; Broderick, William E; Hoffman, Brian M; Broderick, Joan B

    2018-06-28

    Radical S-adenosyl-L-methionine (SAM) en-zymes comprise a vast superfamily catalyzing diverse reactions essential to all life through ho-molytic SAM cleavage to liberate the highly-reactive 5-deoxyadenosyl radical (5-dAdo•). Our recent observation of a catalytically compe-tent organometallic intermediate Ω that forms dur-ing reaction of the radical SAM (RS) enzyme py-ruvate formate-lyase activating-enzyme (PFL-AE) was therefore quite surprising, and led to the question of its broad relevance in the superfamily. We now show that Ω in PFL-AE forms as an in-termediate under a variety of mixing order condi-tions, suggesting it is central to catalysis in this enzyme. We further demonstrate that Ω forms in a suite of RS enzymes chosen to span the totality of superfamily reaction types, implicating Ω as essential in catalysis across the RS superfamily. Finally, EPR and electron nuclear double reso-nance spectroscopy establish that Ω involves an Fe-C5 bond between 5-dAdo• and the [4Fe-4S] cluster. An analogous organometallic bond is found in the well-known adenosylcobalamin (co-enzyme B12) cofactor used to initiate radical reac-tions via a 5'-dAdo• intermediate. Generation of a 5'-dAdo• intermediate via homolytic metal-carbon bond cleavage thus appears to be similar for Ω and coenzyme B12. However coenzyme B12 is involved in enzymes catalyzing of only a small number (~12) of distinct reactions, while the RS superfamily has more than 100,000 distinct se-quences and over 80 reaction types character-ized to date. The appearance of Ω across the RS superfamily therefore dramatically enlarges the sphere of bio-organometallic chemistry in Nature.

  19. Youth De-Radicalization: A Canadian Framework

    Directory of Open Access Journals (Sweden)

    Hafal (Haval Ahmad

    2017-09-01

    Full Text Available Youth radicalization leading to violence has become a growing fear among Canadians, as terrorist attacks are carried out in Western states. Although Canada has suffered relatively fewer acts of violence, this fear has intensified and a de-radicalization strategy is needed in the Canadian context. In a qualitative case study methodology, interviews were conducted with school counsellors, religious leaders, and academics to explore solutions to youth radicalization. Youth de-radicalization approaches from the United Kingdom were analyzed and found that community-based initiatives were missing from programming. Social identity theory is used to explain that youth join radicalized groups to feel a sense of belonging and have to be provided an alternative and moderate group identity to de-radicalize. This study found youth de-radicalization in Canada is best served through a community collaboration approach.

  20. Chemical repair of trypsin-histidinyl radical

    International Nuclear Information System (INIS)

    Jovanovic, S.V.; Ruvarac, I.; Jankovic, I.; Josimovic, L.

    1991-01-01

    Oxyl radicals, such as hydroxyl, alkoxyl and peroxyl, react with biomolecules to produce bioradicals. Unless chemically repaired by suitable antioxidants, these bioradicals form stable products. This leads to loss of biological function of parent biomolecules with deleterious biological results, such as mutagenesis and cancer. Consequently, the understanding of the mechanisms of oxyl radical damage to biomolecules and chemical repair of such damage is crucial for the development of strategies for anticarcinogenesis and radioprotection. In this study the chemical repair of the histidinyl radical generated upon the trichloromethylperoxyl radical reaction with trypsin vas investigated by gamma radiolysis. The trypsin histidinyl radical is a resonance-stabilized heterocyclic free radical which was found to be unreactive with oxygen. The efficacy of the chemical repair of the trypsin-histidinyl radical by endogenous antioxidants which are electron donors (e.g. 5-hydroxytryptophan, uric acid) is compared to that of antioxidants which are H-atom donors (e. g. glutathione). 9 refs., 2 figs., 1 tab

  1. FAR RIGHT RADICALIZATION AND SOCIALIST RADICALIZATION IN INTERWAR ROMANIA

    Directory of Open Access Journals (Sweden)

    IONUŢ BUTOI

    2017-03-01

    Full Text Available In his comments on Mircea Vulcănescu. O microistorie a interbelicului românesc (Eikon, 2015, Emanuel Copilaş states that, regarding the cause of the far right radicalization manifested in the interwar Romania, I share the same historical explanation about fascism as Ernst Nolte. In this concise answer, I explain why this is an unsuitable comparison by summarizing the historiographical perspective I use in the cited volume. Nevertheless, Copilaş’s comments are reopening a debate about how to explain the Romanian fascism

  2. Iron Sulfur and Molybdenum Cofactor Enzymes Regulate the Drosophila Life Cycle by Controlling Cell Metabolism

    Science.gov (United States)

    Marelja, Zvonimir; Leimkühler, Silke; Missirlis, Fanis

    2018-01-01

    Iron sulfur (Fe-S) clusters and the molybdenum cofactor (Moco) are present at enzyme sites, where the active metal facilitates electron transfer. Such enzyme systems are soluble in the mitochondrial matrix, cytosol and nucleus, or embedded in the inner mitochondrial membrane, but virtually absent from the cell secretory pathway. They are of ancient evolutionary origin supporting respiration, DNA replication, transcription, translation, the biosynthesis of steroids, heme, catabolism of purines, hydroxylation of xenobiotics, and cellular sulfur metabolism. Here, Fe-S cluster and Moco biosynthesis in Drosophila melanogaster is reviewed and the multiple biochemical and physiological functions of known Fe-S and Moco enzymes are described. We show that RNA interference of Mocs3 disrupts Moco biosynthesis and the circadian clock. Fe-S-dependent mitochondrial respiration is discussed in the context of germ line and somatic development, stem cell differentiation and aging. The subcellular compartmentalization of the Fe-S and Moco assembly machinery components and their connections to iron sensing mechanisms and intermediary metabolism are emphasized. A biochemically active Fe-S core complex of heterologously expressed fly Nfs1, Isd11, IscU, and human frataxin is presented. Based on the recent demonstration that copper displaces the Fe-S cluster of yeast and human ferredoxin, an explanation for why high dietary copper leads to cytoplasmic iron deficiency in flies is proposed. Another proposal that exosomes contribute to the transport of xanthine dehydrogenase from peripheral tissues to the eye pigment cells is put forward, where the Vps16a subunit of the HOPS complex may have a specialized role in concentrating this enzyme within pigment granules. Finally, we formulate a hypothesis that (i) mitochondrial superoxide mobilizes iron from the Fe-S clusters in aconitase and succinate dehydrogenase; (ii) increased iron transiently displaces manganese on superoxide dismutase, which

  3. Hydrogen Activation by Biomimetic [NiFe]-Hydrogenase Model Containing Protected Cyanide Cofactors

    Science.gov (United States)

    Manor, Brian C.; Rauchfuss, Thomas B.

    2013-01-01

    Described are experiments that allow incorporation of cyanide cofactors and hydride substrate into active site models [NiFe]-hydrogenases (H2ases). Complexes of the type (CO)2(CN)2Fe(pdt)Ni(dxpe), (dxpe = dppe, 1; dxpe = dcpe, 2) bind the Lewis acid B(C6F5)3 (BArF3) to give the adducts (CO)2(CNBArF3)2Fe(pdt)Ni(dxpe), (1(BArF3)2, 2(BArF3)2). Upon decarbonylation using amine oxides, these adducts react with H2 to give hydrido derivatives Et4N[(CO)(CNBArF3)2Fe(H)(pdt)Ni(dxpe)], (dxpe = dppe, Et4N[H3(BArF3)2]; dxpe = dcpe, Et4N[H4(BArF3)2]). Crystallographic analysis shows that Et4N[H3(BArF3)2] generally resembles the active site of the enzyme in the reduced, hydride-containing states (Ni-C/R). The Fe-H…Ni center is unsymmetrical with rFe-H = 1.51(3) and rNi-H = 1.71(3) Å. Both crystallographic and 19F NMR analysis show that the CNBArF3− ligands occupy basal and apical sites. Unlike cationic Ni-Fe hydrides, [H3(BArF3)2]− and [H4(BArF3)2]− oxidize at mild potentials, near the Fc+/0 couple. Electrochemical measurements indicate that in the presence of base, [H3(BArF3)2]− catalyzes the oxidation of H2. NMR evidence indicates dihydrogen bonding between these anionic hydrides and ammonium salts, which is relevant to the mechanism of hydrogenogenesis. In the case of Et4N[H3(BArF3)2], strong acids such as HCl induce H2 release to give the chloride Et4N[(CO)(CNBArF3)2Fe(pdt)(Cl)Ni(dppe)]. PMID:23899049

  4. Iron Sulfur and Molybdenum Cofactor Enzymes Regulate the Drosophila Life Cycle by Controlling Cell Metabolism

    Directory of Open Access Journals (Sweden)

    Zvonimir Marelja

    2018-02-01

    Full Text Available Iron sulfur (Fe-S clusters and the molybdenum cofactor (Moco are present at enzyme sites, where the active metal facilitates electron transfer. Such enzyme systems are soluble in the mitochondrial matrix, cytosol and nucleus, or embedded in the inner mitochondrial membrane, but virtually absent from the cell secretory pathway. They are of ancient evolutionary origin supporting respiration, DNA replication, transcription, translation, the biosynthesis of steroids, heme, catabolism of purines, hydroxylation of xenobiotics, and cellular sulfur metabolism. Here, Fe-S cluster and Moco biosynthesis in Drosophila melanogaster is reviewed and the multiple biochemical and physiological functions of known Fe-S and Moco enzymes are described. We show that RNA interference of Mocs3 disrupts Moco biosynthesis and the circadian clock. Fe-S-dependent mitochondrial respiration is discussed in the context of germ line and somatic development, stem cell differentiation and aging. The subcellular compartmentalization of the Fe-S and Moco assembly machinery components and their connections to iron sensing mechanisms and intermediary metabolism are emphasized. A biochemically active Fe-S core complex of heterologously expressed fly Nfs1, Isd11, IscU, and human frataxin is presented. Based on the recent demonstration that copper displaces the Fe-S cluster of yeast and human ferredoxin, an explanation for why high dietary copper leads to cytoplasmic iron deficiency in flies is proposed. Another proposal that exosomes contribute to the transport of xanthine dehydrogenase from peripheral tissues to the eye pigment cells is put forward, where the Vps16a subunit of the HOPS complex may have a specialized role in concentrating this enzyme within pigment granules. Finally, we formulate a hypothesis that (i mitochondrial superoxide mobilizes iron from the Fe-S clusters in aconitase and succinate dehydrogenase; (ii increased iron transiently displaces manganese on superoxide

  5. Tubulin binding cofactor C (TBCC) suppresses tumor growth and enhances chemosensitivity in human breast cancer cells

    International Nuclear Information System (INIS)

    Hage-Sleiman, Rouba; Herveau, Stéphanie; Matera, Eva-Laure; Laurier, Jean-Fabien; Dumontet, Charles

    2010-01-01

    Microtubules are considered major therapeutic targets in patients with breast cancer. In spite of their essential role in biological functions including cell motility, cell division and intracellular transport, microtubules have not yet been considered as critical actors influencing tumor cell aggressivity. To evaluate the impact of microtubule mass and dynamics on the phenotype and sensitivity of breast cancer cells, we have targeted tubulin binding cofactor C (TBCC), a crucial protein for the proper folding of α and β tubulins into polymerization-competent tubulin heterodimers. We developed variants of human breast cancer cells with increased content of TBCC. Analysis of proliferation, cell cycle distribution and mitotic durations were assayed to investigate the influence of TBCC on the cell phenotype. In vivo growth of tumors was monitored in mice xenografted with breast cancer cells. The microtubule dynamics and the different fractions of tubulins were studied by time-lapse microscopy and lysate fractionation, respectively. In vitro sensitivity to antimicrotubule agents was studied by flow cytometry. In vivo chemosensitivity was assayed by treatment of mice implanted with tumor cells. TBCC overexpression influenced tubulin fraction distribution, with higher content of nonpolymerizable tubulins and lower content of polymerizable dimers and microtubules. Microtubule dynamicity was reduced in cells overexpressing TBCC. Cell cycle distribution was altered in cells containing larger amounts of TBCC with higher percentage of cells in G2-M phase and lower percentage in S-phase, along with slower passage into mitosis. While increased content of TBCC had little effect on cell proliferation in vitro, we observed a significant delay in tumor growth with respect to controls when TBCC overexpressing cells were implanted as xenografts in vivo. TBCC overexpressing variants displayed enhanced sensitivity to antimicrotubule agents both in vitro and in xenografts. These

  6. The human membrane cofactor CD46 is a receptor for species B adenovirus serotype 3.

    Science.gov (United States)

    Sirena, Dominique; Lilienfeld, Benjamin; Eisenhut, Markus; Kälin, Stefan; Boucke, Karin; Beerli, Roger R; Vogt, Lorenz; Ruedl, Christiane; Bachmann, Martin F; Greber, Urs F; Hemmi, Silvio

    2004-05-01

    Many human adenovirus (Ad) serotypes use the coxsackie B virus-Ad receptor (CAR). Recently, CD46 was suggested to be a receptor of species B Ad serotype 11 (Ad11), Ad14, Ad16, Ad21, Ad35, and Ad50. Using Sindbis virus-mediated cDNA library expression, we identify here the membrane cofactor protein CD46 as a surface receptor of species B Ad3. All four major CD46 transcripts and one minor CD46 transcript expressed in nucleated human cells were isolated. Rodent BHK cells stably expressing the BC1 form of CD46 bound radiolabeled Ad3 with a dissociation constant of 0.3 nM, identical to that of CD46-positive HeLa cells expressing twice as many Ad3 binding sites. Pull-down experiments with recombinant Ad3 fibers and a soluble form of the CD46 extracellular domain linked to the Fc portion of human immunoglobulin G (CD46ex-Fc) indicated direct interactions of the Ad3 fiber knob with CD46ex-Fc but not CARex-Fc (Fc-linked extracellular domain of CAR). Ad3 colocalized with cell surface CD46 in both rodent and human cells at the light and electron microscopy levels. Anti-CD46 antibodies and CD46ex-Fc inhibited Ad3 binding to CD46-expressing BHK cells more than 10-fold and to human cells 2-fold. In CD46-expressing BHK cells, wild-type Ad3 and a chimeric Ad consisting of the Ad5 capsid and the Ad3 fiber elicited dose-dependent cytopathic effects and transgene expression, albeit less efficiently than in human cells. Together, our results show that all of the major splice forms of CD46 are predominant and functional binding sites of Ad3 on CD46-expressing rodent and human cells but may not be the sole receptor of species B Ads on human cells. These results have implications for understanding viral pathogenesis and therapeutic gene delivery.

  7. Radical probing of spliceosome assembly.

    Science.gov (United States)

    Grewal, Charnpal S; Kent, Oliver A; MacMillan, Andrew M

    2017-08-01

    Here we describe the synthesis and use of a directed hydroxyl radical probe, tethered to a pre-mRNA substrate, to map the structure of this substrate during the spliceosome assembly process. These studies indicate an early organization and proximation of conserved pre-mRNA sequences during spliceosome assembly. This methodology may be adapted to the synthesis of a wide variety of modified RNAs for use as probes of RNA structure and RNA-protein interaction. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Iron and iron derived radicals

    International Nuclear Information System (INIS)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fast! Think small! In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab

  9. Remembering Dutch-Moluccan radicalism

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2016-01-01

    This article examines memory politics in relation to radical actions of young Dutch-Moluccans, more specifically a train hijacking in 1977 at the village of De Punt in the Netherlands. The article examines how these historical events were remembered in the drama-documentary television film, De Punt...... of the web debate examines how viewers reacted to this interpretation. The web debate functioned as a participatory forum, where collective and national memories and postcolonial history were intensely discussed, and the debate made room for some degree of reconciliation between viewers of Dutch......-Moluccan and of Dutch majority background...

  10. Laser spectroscopy of hydrocarbon radicals

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [Harvard Univ., Cambridge, MA (United States)

    1993-12-01

    The author reports the application of supersonic jet flash pyrolysis to the specific preparation of a range of organic radicals, biradicals, and carbenes in a skimmed molecular beam. Each species was produced cleanly and specifically, with little or no secondary reactions by the thermal dissociation of appropriately designed and synthesized organic precursors. Photoelectron spectra of the three isomeric C{sub 3}H{sub 2} carbenes, ortho-benzyne, and the {alpha},3-dehydrotoluene biradical, were used to establish adiabatic ionization potentials for use in thermochemical determinations.

  11. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  12. Radical constructivism: Between realism and solipsism

    Science.gov (United States)

    Martínez-Delgado, Alberto

    2002-11-01

    This paper criticizes radical constructivism of the Glasersfeld type, pointing out some contradictions between the declared radical principles and their theoretical and practical development. These contradictions manifest themselves in a frequent oscillation between solipsism and realism, despite constructivist claims to be an anti-realist theory. The paper also points out the contradiction between the relativism of the radical constructivist principles and the constructivist exclusion of other epistemological or educational paradigms. It also disputes the originality and importance of the radical constructivist paradigm, suggesting the idea of an isomorphism between radical constructivist theory and contemplative realism. In addition, some pedagogical and scientific methodological aspects of the radical constructivist model are examined. Although radical constructivism claims to be a rational theory and advocates deductive thinking, it is argued that there is no logical deductive connection between the radical principles of constructivism and the radical constructivist ideas about scientific research and learning. The paper suggests the possibility of an ideological substratum in the construction and hegemonic success of subjective constructivism and, finally, briefly advances an alternative realist model to epistemological and educational radical constructivism.

  13. Oxidation of the FAD cofactor to the 8-formyl-derivative in human electron-transferring flavoprotein

    Science.gov (United States)

    Augustin, Peter; Toplak, Marina; Fuchs, Katharina; Gerstmann, Eva Christine; Prassl, Ruth; Winkler, Andreas; Macheroux, Peter

    2018-01-01

    The heterodimeric human (h) electron-transferring flavoprotein (ETF) transfers electrons from at least 13 different flavin dehydrogenases to the mitochondrial respiratory chain through a non-covalently bound FAD cofactor. Here, we describe the discovery of an irreversible and pH-dependent oxidation of the 8α-methyl group to 8-formyl-FAD (8f-FAD), which represents a unique chemical modification of a flavin cofactor in the human flavoproteome. Furthermore, a set of hETF variants revealed that several conserved amino acid residues in the FAD-binding pocket of electron-transferring flavoproteins are required for the conversion to the formyl group. Two of the variants generated in our study, namely αR249C and αT266M, cause glutaric aciduria type II, a severe inherited disease. Both of the variants showed impaired formation of 8f-FAD shedding new light on the potential molecular cause of disease development. Interestingly, the conversion of FAD to 8f-FAD yields a very stable flavin semiquinone that exhibited slightly lower rates of electron transfer in an artificial assay system than hETF containing FAD. In contrast, the formation of 8f-FAD enhanced the affinity to human dimethylglycine dehydrogenase 5-fold, indicating that formation of 8f-FAD modulates the interaction of hETF with client enzymes in the mitochondrial matrix. Thus, we hypothesize that the FAD cofactor bound to hETF is subject to oxidation in the alkaline (pH 8) environment of the mitochondrial matrix, which may modulate electron transport between client dehydrogenases and the respiratory chain. This discovery challenges the current concepts of electron transfer processes in mitochondria. PMID:29301933

  14. Identification of the APC/C co-factor FZR1 as a novel therapeutic target for multiple myeloma.

    Science.gov (United States)

    Crawford, Lisa J; Anderson, Gordon; Johnston, Cliona K; Irvine, Alexandra E

    2016-10-25

    Multiple Myeloma (MM) is a haematological neoplasm characterised by the clonal proliferation of malignant plasma cells in the bone marrow. The success of proteasome inhibitors in the treatment of MM has highlighted the importance of the ubiquitin proteasome system (UPS) in the pathogenesis of this disease. In this study, we analysed gene expression of UPS components to identify novel therapeutic targets within this pathway in MM. Here we demonstrate how this approach identified previously validated and novel therapeutic targets. In addition we show that FZR1 (Fzr), a cofactor of the multi-subunit E3 ligase complex anaphase-promoting complex/cyclosome (APC/C), represents a novel therapeutic target in myeloma. The APC/C associates independently with two cofactors, Fzr and Cdc20, to control cell cycle progression. We found high levels of FZR1 in MM primary cells and cell lines and demonstrate that expression is further increased on adhesion to bone marrow stromal cells (BMSCs). Specific knockdown of either FZR1 or CDC20 reduced viability and induced growth arrest of MM cell lines, and resulted in accumulation of APC/CFzr substrate Topoisomerase IIα (TOPIIα) or APC/CCdc20 substrate Cyclin B. Similar effects were observed following treatment with proTAME, an inhibitor of both APC/CFzr and APC/CCdc20. Combinations of proTAME with topoisomerase inhibitors, etoposide and doxorubicin, significantly increased cell death in MM cell lines and primary cells, particularly if TOPIIα levels were first increased through pre-treatment with proTAME. Similarly, combinations of proTAME with the microtubule inhibitor vincristine resulted in enhanced cell death. This study demonstrates the potential of targeting the APC/C and its cofactors as a therapeutic approach in MM.

  15. Niveles plasmáticos e interacciones del sistema cofactor 2 de la heparina-trombina-dermatan sulfato

    OpenAIRE

    Rossi, Eleonora Beatriz

    1999-01-01

    El Cofactor II de la Heparina (HCII) es un inhibidor fisiológico del sistema de coagulación, miembro de la familia de serpinas. Inhibe específicamente trombina, una enzima clave del sistema hemostático. La capacidad del HCII de inhibir trombina es potenciada mas de 1000 veces por la presencia de glicosaminoglicano el Dermatán Sulfato (DS),. Aún no está claramente definido el papel que desempeña el HCII en la fisiología de la Hemostasia, postulándose su deficiencia corno leve factor de riesgo ...

  16. Integrating biocompatible chemistry and manipulating cofactor partitioning in metabolically engineeredLactococcus lactisfor fermentative production of (3S)-acetoin

    DEFF Research Database (Denmark)

    Liu, Jianming; Solem, Christian; Jensen, Peter Ruhdal

    2016-01-01

    Biocompatible chemistry (BC), i.e. non-enzymatic chemical reactions compatible with living organisms, is increasingly used in conjunction with metabolically engineered microorganisms for producing compounds that do not usually occur naturally. Here we report production of one such compound, (3S......)-acetoin, a valuable precursor for chiral synthesis, using a metabolically engineered Lactococcus lactis strain growing under respiratory conditions with ferric iron serving as a BC component. The strain used has all competing product pathways inactivated, and an appropriate cofactor balance is achieved by fine...

  17. Structural evidence for the partially oxidized dipyrromethene and dipyrromethanone forms of the cofactor of porphobilinogen deaminase: structures of the Bacillus megaterium enzyme at near-atomic resolution

    International Nuclear Information System (INIS)

    Azim, N.; Deery, E.; Warren, M. J.; Wolfenden, B. A. A.; Erskine, P.; Cooper, J. B.; Coker, A.; Wood, S. P.; Akhtar, M.

    2014-01-01

    The enzyme porphobilinogen deaminase (PBGD; hydroxymethylbilane synthase; EC 2.5.1.61) catalyses a key early step in the biosynthesis of tetrapyrroles in which four molecules of the monopyrrole porphobilinogen are condensed to form a linear tetrapyrrole. Two near-atomic resolution structures of PBGD from B. megaterium are reported that demonstrate the time-dependent accumulation of partially oxidized forms of the cofactor, including one that possesses a tetrahedral C atom in the terminal pyrrole ring. The enzyme porphobilinogen deaminase (PBGD; hydroxymethylbilane synthase; EC 2.5.1.61) catalyses an early step of the tetrapyrrole-biosynthesis pathway in which four molecules of the monopyrrole porphobilinogen are condensed to form a linear tetrapyrrole. The enzyme possesses a dipyrromethane cofactor, which is covalently linked by a thioether bridge to an invariant cysteine residue (Cys241 in the Bacillus megaterium enzyme). The cofactor is extended during the reaction by the sequential addition of the four substrate molecules, which are released as a linear tetrapyrrole product. Expression in Escherichia coli of a His-tagged form of B. megaterium PBGD has permitted the X-ray analysis of the enzyme from this species at high resolution, showing that the cofactor becomes progressively oxidized to the dipyrromethene and dipyrromethanone forms. In previously solved PBGD structures, the oxidized cofactor is in the dipyromethenone form, in which both pyrrole rings are approximately coplanar. In contrast, the oxidized cofactor in the B. megaterium enzyme appears to be in the dipyrromethanone form, in which the C atom at the bridging α-position of the outer pyrrole ring is very clearly in a tetrahedral configuration. It is suggested that the pink colour of the freshly purified protein is owing to the presence of the dipyrromethene form of the cofactor which, in the structure reported here, adopts the same conformation as the fully reduced dipyrromethane form

  18. Intramolecular transformation of thiyl radicals to α-aminoalkyl radicals: 'ab initio' calculations on homocystein

    International Nuclear Information System (INIS)

    Chhun, S.; Berges, J.; Bleton, V.; Abedinzadeh, Z.

    2000-01-01

    One-electron oxidation of thiols by oxidizing radicals leads to the formation of thiyl radical and carbon-centered radicals. It has been shown experimentally that in the absence of oxygen, the thiyl radicals derived from certain thiols of biological interest such as glutathion, cysteine and homocysteine decay rapidly by intramolecular rearrangement reactions into the carbon-centered radical. In the present work we have investigated theoretically the structure and the stability of thiyl and carbon-centered radicals of homocysteine in order to check the possibility of this rearrangement. (author)

  19. Radicalization In Pakistan And The Spread Of Radical Islam In Pakistan

    Directory of Open Access Journals (Sweden)

    Bahir ahmad

    2015-08-01

    Full Text Available ABSTRACT It is pertinent to mention that radicalism is not intrinsic to Islam and radical interpretations of the religion or for that matter may occur within any way of life and religion Saikal 2003 and yet the question remains as to why Muslims in certain geographical regions have more radical approaches towards their religion and also that what are the causes of such radicalization. Becoming a radical Muslim is not even a matter of a day nor is it a sudden process. There are several reasons behind making a person radical peaceful angry smiling or tolerant. For knowing the reason behind radicalization or radicals persons one has to understand the causes. Tracing these causes is one of the ways to eliminate such behavior. The first step in the elimination of the radical sentiments in a person is to develop peace in his personality Fair Malhotra amp Shapiro 2010. The chapter which has been addressed here is going to shed light on the roots and symptoms of the radicalism. There will be a brief discussion on how the roots of radicalism can be traced and can be eliminated. The assessment and discussion will be conducted on the parameters of the economy media politics and theology from social cultural point of view. According to the analysis of Ahrari 2000 political factor is one of the major and direct factors which have resulted in causing of the radicalism. These factors however intertwine with one another. Radical actions cannot take place only because of the political factors.

  20. Fluorescence lifetime measurement of radical ions

    International Nuclear Information System (INIS)

    Ichinose, Nobuyuki; Kinugasa, Jun-ichiro; Hagiri, Masahide; Nakayama, Toshihiro; Murakami, Hiroshi; Kishimoto, Maki; Daido, Hiroyuki

    2004-01-01

    One-photonic excitation of a charge transfer complex of hexamethoxybenzene (HMB) and nitrosonium tetrafluoroborate (NO + BF 4 - ) in acetonitrile afforded fluorescences emission from excited radical cation of HMB (HMB + *). Lifetime of the excited radical ion species was measured to be 7 ps by the pump-probe transient absorption technique. The lifetime was much shorter than that of free radical ion (63 ps), indicating the presence of an interaction between HMB + * and NO in the excited complex. (author)

  1. Reorientation dynamics of cyclohexadienyl radicals in zeolites

    International Nuclear Information System (INIS)

    Stolmar, M.; Roduner, E.; Dilger, H.; Himmer, U.; Shelley, M.; Reid, I.D.

    1997-01-01

    The dynamics of the muonium substituted cyclohexadienyl radical adsorbed on silicalite and NaZSM-5 is investigated by means of avoided level crossing muon spin resonance. The influence of benzene loading on the mobility of the radical is studied. At low loadings the radicals were found to be located on a single adsorption site where they undergo a wobbling type of motion. With increasing loading an additional species adsorbed on a different site is observed

  2. The Rise of Radicals in Bioinorganic Chemistry

    OpenAIRE

    Gray, Harry B.; Winkler, Jay R.

    2016-01-01

    Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O_2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) a...

  3. Inactivation of Lactobacillus leichmannii ribonucleotide reductase by 2',2'-difluoro-2'-deoxycytidine 5'-triphosphate: adenosylcobalamin destruction and formation of a nucleotide-based radical.

    Science.gov (United States)

    Lohman, Gregory J S; Gerfen, Gary J; Stubbe, Joanne

    2010-02-23

    Ribonucleotide reductase (RNR, 76 kDa) from Lactobacillus leichmannii is a class II RNR that requires adenosylcobalamin (AdoCbl) as a cofactor. It catalyzes the conversion of nucleoside triphosphates to deoxynucleotides and is 100% inactivated by 1 equiv of 2',2'-difluoro-2'-deoxycytidine 5'-triphosphate (F(2)CTP) in cytidine, characterized by mass spectrometry and NMR spectroscopy, indicating the trapped nucleotide had lost both of its fluorides and gained an oxygen. High-field ENDOR studies with [1'-(2)H]F(2)CTP from the reaction quenched at 30 s revealed a radical that is nucleotide-based. The relationship between this radical and the trapped cytidine analogue provides insight into the nonalkylative pathway for RNR inactivation relative to the alkylative pathway.

  4. Spectroscopic studies of the iron and manganese reconstituted tyrosyl radical in Bacillus cereus ribonucleotide reductase R2 protein.

    Directory of Open Access Journals (Sweden)

    Ane B Tomter

    Full Text Available Ribonucleotide reductase (RNR catalyzes the rate limiting step in DNA synthesis where ribonucleotides are reduced to the corresponding deoxyribonucleotides. Class Ib RNRs consist of two homodimeric subunits: R1E, which houses the active site; and R2F, which contains a metallo cofactor and a tyrosyl radical that initiates the ribonucleotide reduction reaction. We studied the R2F subunit of B. cereus reconstituted with iron or alternatively with manganese ions, then subsequently reacted with molecular oxygen to generate two tyrosyl-radicals. The two similar X-band EPR spectra did not change significantly over 4 to 50 K. From the 285 GHz EPR spectrum of the iron form, a g(1-value of 2.0090 for the tyrosyl radical was extracted. This g(1-value is similar to that observed in class Ia E. coli R2 and class Ib R2Fs with iron-oxygen cluster, suggesting the absence of hydrogen bond to the phenoxyl group. This was confirmed by resonance Raman spectroscopy, where the stretching vibration associated to the radical (C-O, ν(7a = 1500 cm(-1 was found to be insensitive to deuterium-oxide exchange. Additionally, the (18O-sensitive Fe-O-Fe symmetric stretching (483 cm(-1 of the metallo-cofactor was also insensitive to deuterium-oxide exchange indicating no hydrogen bonding to the di-iron-oxygen cluster, and thus, different from mouse R2 with a hydrogen bonded cluster. The HF-EPR spectrum of the manganese reconstituted RNR R2F gave a g(1-value of ∼2.0094. The tyrosyl radical microwave power saturation behavior of the iron-oxygen cluster form was as observed in class Ia R2, with diamagnetic di-ferric cluster ground state, while the properties of the manganese reconstituted form indicated a magnetic ground state of the manganese-cluster. The recent activity measurements (Crona et al., (2011 J Biol Chem 286: 33053-33060 indicates that both the manganese and iron reconstituted RNR R2F could be functional. The manganese form might be very important, as it has 8

  5. Structural insights into the cofactor-assisted substrate recognition of yeast methylglyoxal/isovaleraldehyde reductase Gre2.

    Science.gov (United States)

    Guo, Peng-Chao; Bao, Zhang-Zhi; Ma, Xiao-Xiao; Xia, Qingyou; Li, Wei-Fang

    2014-09-01

    Saccharomyces cerevisiae Gre2 (EC1.1.1.283) serves as a versatile enzyme that catalyzes the stereoselective reduction of a broad range of substrates including aliphatic and aromatic ketones, diketones, as well as aldehydes, using NADPH as the cofactor. Here we present the crystal structures of Gre2 from S. cerevisiae in an apo-form at 2.00Å and NADPH-complexed form at 2.40Å resolution. Gre2 forms a homodimer, each subunit of which contains an N-terminal Rossmann-fold domain and a variable C-terminal domain, which participates in substrate recognition. The induced fit upon binding to the cofactor NADPH makes the two domains shift toward each other, producing an interdomain cleft that better fits the substrate. Computational simulation combined with site-directed mutagenesis and enzymatic activity analysis enabled us to define a potential substrate-binding pocket that determines the stringent substrate stereoselectivity for catalysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Cofactor and CO2 donor regulation involved in reductive routes for polymalic acid production by Aureobasidium pullulans CCTCC M2012223.

    Science.gov (United States)

    Zou, Xiang; Tu, Guangwei; Zan, Zhanquan

    2014-10-01

    Polymalic acid (PMA) is a water-soluble polyester with many attractive properties for biomedical application. Its monomer L-malic acid is widely used in the food industry and also a potential C4 platform chemical. Cofactor and CO2 donor involved in the reductive routes were investigated for PMA production by Aureobasidium pullulans. Biotin as the key cofactor of pyruvate carboxylase was favor for the PMA biosynthesis. Na2CO3 as CO2 donor can obviously improved PMA titer when compared with no CO2 supplier NaOH, and also exhibit more advantages than the other donor CaCO3 because of its water-soluble characteristic. A combinational process with addition of biotin 70 mg/L and Na2CO3 as the CO2 donor was scaled-up in 50 L fermentor, achieving the high product 34.3 g/L of PMA and productivity of 0.41 g/L h. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application.

  7. Purification, crystallization and preliminary crystallographic analysis of a multiple cofactor-dependent DNA ligase from Sulfophobococcus zilligii

    International Nuclear Information System (INIS)

    Supangat, Supangat; An, Young Jun; Sun, Younguk; Kwon, Suk-Tae; Cha, Sun-Shin

    2010-01-01

    A recombinant multiple cofactor-dependent DNA ligase from S. zilligii has been purified and crystallized. X-ray diffraction data were collected to 2.9 Å resolution and the crystals belonged to space group P1. A recombinant DNA ligase from Sulfophobococcus zilligii that shows multiple cofactor specificity (ATP, ADP and GTP) was expressed in Escherichia coli and purified under reducing conditions. Crystals were obtained by the microbatch crystallization method at 295 K in a drop containing 1 µl protein solution (10 mg ml −1 ) and an equal volume of mother liquor [0.1 M HEPES pH 7.5, 10%(w/v) polyethylene glycol 10 000]. A data set was collected to 2.9 Å resolution using synchrotron radiation. The crystals belonged to space group P1, with unit-cell parameters a = 63.7, b = 77.1, c = 77.8 Å, α = 83.4, β = 82.4, γ = 74.6°. Assuming the presence of two molecules in the unit cell, the solvent content was estimated to be about 53.4%

  8. Lineage-Specific Viral Hijacking of Non-canonical E3 Ubiquitin Ligase Cofactors in the Evolution of Vif Anti-APOBEC3 Activity

    Directory of Open Access Journals (Sweden)

    Joshua R. Kane

    2015-05-01

    Full Text Available HIV-1 encodes the accessory protein Vif, which hijacks a host Cullin-RING ubiquitin ligase (CRL complex as well as the non-canonical cofactor CBFβ, to antagonize APOBEC3 antiviral proteins. Non-canonical cofactor recruitment to CRL complexes by viral factors, to date, has only been attributed to HIV-1 Vif. To further study this phenomenon, we employed a comparative approach combining proteomic, biochemical, structural, and virological techniques to investigate Vif complexes across the lentivirus genus, including primate (HIV-1 and simian immunodeficiency virus macaque [SIVmac] and non-primate (FIV, BIV, and MVV viruses. We find that CBFβ is completely dispensable for the activity of non-primate lentiviral Vif proteins. Furthermore, we find that BIV Vif requires no cofactor and that MVV Vif requires a novel cofactor, cyclophilin A (CYPA, for stable CRL complex formation and anti-APOBEC3 activity. We propose modular conservation of Vif complexes allows for potential exaptation of functions through the acquisition of non-CRL-associated host cofactors while preserving anti-APOBEC3 activity.

  9. The Games Radicals Play: Special Issue on Free Radicals and Radical Ions

    Directory of Open Access Journals (Sweden)

    John C. Walton

    2015-02-01

    Full Text Available Chemistry and Physics have aptly been described as “most excellent children of Intellect and Art” [1]. Both these “children” engage with many playthings, and molecules rank as one of their first favorites, especially radicals, which are amongst the most lively and exciting. Checking out radicals dancing to the music of entropy round their potential energy ballrooms is surely both entertaining and enlightening. Radicals’ old favorite convolutions are noteworthy, but the new styles, modes and arrangements appearing on the scene are even more interesting. Some of these are ephemeral and enjoy only a brief appearance, others are retro-types reappearing in new guises, still others are genuinely new and “go viral” in the scientific world. This Special Issue of Molecules contains the observations and reflections of a select group of chemists and physicists fascinated by this spectacle. It contains an eclectic mix reflecting on new modes and advances as well as on permutations and combinations that revive mature themes. [...

  10. Students' Ideas and Radical Constructivism

    Science.gov (United States)

    Sánchez Gómez, Pedro J.

    2016-08-01

    In this article, I study, from the point of view of the analytic philosophy of mind, the compatibility of students' ideas studies (SIS) with radical constructivism (RC). I demonstrate that RC is based on a psychology of narrow mental states; that is, the idea that the mental content of an individual can be fully characterised without any reference external to her or him. I show that this fact imposes some severe restrictions to SIS to be incorporated into RC. In particular, I argue that only qualitative studies can comply with the requirement of narrowness. Nevertheless, I propose that quantitative works can be employed as sources of types in order to study token actual students. I use this type-token dichotomy to put forward an outline of a theory of the relation between school contents and mental contents. In this view, token mental contents regarding a given topic can be defined, and probed, only by resorting to typical school contents.

  11. DNA Binding Hydroxyl Radical Probes.

    Science.gov (United States)

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2012-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different chromophores which produce fluorescent products when hydroxylated. Of these, the coumarin system suffers from the fewest disadvantages. We have therefore examined its behavior when linked to a cationic peptide ligand designed to bind strongly to DNA.

  12. Photoionisation of the tropyl radical

    Directory of Open Access Journals (Sweden)

    Kathrin H. Fischer

    2013-04-01

    Full Text Available We present a study on the photoionisation of the cycloheptatrienyl (tropyl radical, C7H7, using tunable vacuum ultraviolet synchrotron radiation. Tropyl is generated by flash pyrolysis from bitropyl. Ions and electrons are detected in coincidence, permitting us to record mass-selected photoelectron spectra. The threshold photoelectron spectrum of tropyl, corresponding to the X+ 1A1’ ← X 2E2” transition, reveals an ionisation energy of 6.23 ± 0.02 eV, in good agreement with Rydberg extrapolations, but slightly lower than the value derived from earlier photoelectron spectra. Several vibrations can be resolved and are reassigned to the C–C stretch mode ν16+ and to a combination of ν16+ with the ring breathing mode ν2+. Above 10.55 eV dissociative photoionisation of tropyl is observed, leading to the formation of C5H5+ and C2H2.

  13. Free radicals in biology. Volume II

    International Nuclear Information System (INIS)

    Pryor, W.A.

    1976-01-01

    This volume continues the treatment of topics in free radical biology and free radical pathology from Volume I. In the first chapter, pyridinyl radicals, radicals which are models for those derived from NAD, are discussed. Pyridinyl radicals can be synthesized and isolated and directly studied in a number of chemical systems. The next chapter treats the role of glutathione in the cell. It is becoming even more apparent that this vital thiol controls a large number of important cellular functions. The GSH/GSSG balance has recently been implicated as a control for cellular development; this balance also may be important in relaying the effects of oxidants from one site to another in the body. The next chapter outlines the reactions of singlet oxygen; some of these involve free radicals and some do not. This reactive intermediate appears to be important both in photochemical smog and in cellular chemistry where singlet oxygen is produced by nonphotochemical processes. The production of free radicals from dry tissues, a controversial area with conflicting claims is reviewed. The next chapter outlines the current status of the studies of photochemical smog. The next two chapters treat specific reactive materials which are present in smog. The first discusses the chemistry of nitrogen oxides and ozone. The second chapter treats the chemistry of the peroxyacyl nitrites. These compounds, although present in only small concentration, are among the most toxic components of smog. The last two chapters treat radiation damage to proteins and radiation protection and radical reactions produced by radiation in nucleic acids

  14. Measuring Atmospheric Free Radicals Using Chemical Amplification

    Science.gov (United States)

    1988-05-01

    CH 3Br, H2S, and SO2 [Logan et al., 1981]. Recently, the OH radical has been determined as the dominant loss mechanism for isoprene and monoterpenes ...W. Heaps, D. Philen, and T. McGee, Bondary Layer Measurements of the OH Radical in the Vicinity of an Isolated Power Plant Plume: SO2 and NO2

  15. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  16. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    B. Mourrain; J.B. Lasserre; M. Laurent (Monique); P. Rostalski; P. Trebuchet (Philippe)

    2013-01-01

    htmlabstractIn this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and

  17. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    Lasserre, J.B.; Laurent, M.; Mourrain, B.; Rostalski, P.; Trébuchet, P.

    2013-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming its complex (resp. real) variety is finite. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-definite

  18. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    B. Mourrain; J.B. Lasserre; M. Laurent (Monique); P. Rostalski; P. Trebuchet (Philippe)

    2011-01-01

    htmlabstractIn this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and

  19. Quantification of hydroxyl radical produced during phacoemulsification.

    Science.gov (United States)

    Gardner, Jonathan M; Aust, Steven D

    2009-12-01

    To quantitate hydroxyl radicals produced during phacoemulsification with various irrigating solutions and conditions used in cataract surgery. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. All experiments were performed using an Infiniti Vision System phacoemulsifier with irrigation and aspiration. Hydroxyl radicals were quantitated using electron spin resonance spectroscopy and a spectrophotometric assay for malondialdehyde, which is formed by the oxidation of deoxyribose by the hydroxyl radical. Hydroxyl radical production increased during longitudinal-stroking phacoemulsification as power levels were increased in a nonlinear, nonexponential fashion. The detection of hydroxyl radical was reduced in irrigating solutions containing organic molecules (eg, citrate, acetate, glutathione, dextrose) and further reduced in Navstel, an irrigating solution containing a viscosity-modifying agent, hydroxypropyl methylcellulose. Hydroxyl radicals produced in settings representative of those used in phacoemulsification cataract surgery were quantitated using the deoxyribose method. Hydroxyl radical production was dependent on the level of ultrasound power applied and the irrigating solution used. Oxidative stress on the eye during phacoemulsification may be minimized by using irrigating solutions that contain organic molecules, including the viscosity-modifying agent hydroxypropyl methylcellulose, that can compete for reaction with hydroxyl radicals.

  20. Self-Terminating, Oxidative Radical Cyclizations

    Directory of Open Access Journals (Sweden)

    Uta Wille

    2004-05-01

    Full Text Available The recently discovered novel concept of self-terminating, oxidative radical cyclizations, through which alkynes can be converted into carbonyl compounds under very mild reaction conditions using O-centered inorganic and organic radicals as oxidants, is described

  1. An Appreciation of Free Radical Chemistry

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 9. An Appreciation of Free Radical Chemistry - 6. Experiments Involving Free Radicals. G Nagendrappa. Classroom Volume 10 Issue 9 September 2005 pp 79-84 ...

  2. Radical Behaviorism and Buddhism: Complementarities and Conflicts

    Science.gov (United States)

    Diller, James W.; Lattal, Kennon A.

    2008-01-01

    Comparisons have been made between Buddhism and the philosophy of science in general, but there have been only a few attempts to draw comparisons directly with the philosophy of radical behaviorism. The present review therefore considers heretofore unconsidered points of comparison between Buddhism and radical behaviorism in terms of their…

  3. Protein Cofactors Are Essential for High-Affinity DNA Binding by the Nuclear Factor κB RelA Subunit.

    Science.gov (United States)

    Mulero, Maria Carmen; Shahabi, Shandy; Ko, Myung Soo; Schiffer, Jamie M; Huang, De-Bin; Wang, Vivien Ya-Fan; Amaro, Rommie E; Huxford, Tom; Ghosh, Gourisankar

    2018-05-22

    Transcription activator proteins typically contain two functional domains: a DNA binding domain (DBD) that binds to DNA with sequence specificity and an activation domain (AD) whose established function is to recruit RNA polymerase. In this report, we show that purified recombinant nuclear factor κB (NF-κB) RelA dimers bind specific κB DNA sites with an affinity significantly lower than that of the same dimers from nuclear extracts of activated cells, suggesting that additional nuclear cofactors might facilitate DNA binding by the RelA dimers. Additionally, recombinant RelA binds DNA with relatively low affinity at a physiological salt concentration in vitro. The addition of p53 or RPS3 (ribosomal protein S3) increases RelA:DNA binding affinity 2- to >50-fold depending on the protein and ionic conditions. These cofactor proteins do not form stable ternary complexes, suggesting that they stabilize the RelA:DNA complex through dynamic interactions. Surprisingly, the RelA-DBD alone fails to bind DNA under the same solution conditions even in the presence of cofactors, suggesting an important role of the RelA-AD in DNA binding. Reduced RelA:DNA binding at a physiological ionic strength suggests that multiple cofactors might be acting simultaneously to mitigate the electrolyte effect and stabilize the RelA:DNA complex in vivo. Overall, our observations suggest that the RelA-AD and multiple cofactor proteins function cooperatively to prime the RelA-DBD and stabilize the RelA:DNA complex in cells. Our study provides a mechanism for nuclear cofactor proteins in NF-κB-dependent gene regulation.

  4. Site-Specific Bioconjugation of an Organometallic Electron Mediator to an Enzyme with Retained Photocatalytic Cofactor Regenerating Capacity and Enzymatic Activity

    Directory of Open Access Journals (Sweden)

    Sung In Lim

    2015-04-01

    Full Text Available Photosynthesis consists of a series of reactions catalyzed by redox enzymes to synthesize carbohydrates using solar energy. In order to take the advantage of solar energy, many researchers have investigated artificial photosynthesis systems mimicking the natural photosynthetic enzymatic redox reactions. These redox reactions usually require cofactors, which due to their high cost become a key issue when constructing an artificial photosynthesis system. Combining a photosensitizer and an Rh-based electron mediator (RhM has been shown to photocatalytically regenerate cofactors. However, maintaining the high concentration of cofactors available for efficient enzymatic reactions requires a high concentration of the expensive RhM; making this process cost prohibitive. We hypothesized that conjugation of an electron mediator to a redox enzyme will reduce the amount of electron mediators necessary for efficient enzymatic reactions. This is due to photocatalytically regenerated NAD(PH being readily available to a redox enzyme, when the local NAD(PH concentration near the enzyme becomes higher. However, conventional random conjugation of RhM to a redox enzyme will likely lead to a substantial loss of cofactor regenerating capacity and enzymatic activity. In order to avoid this issue, we investigated whether bioconjugation of RhM to a permissive site of a redox enzyme retains cofactor regenerating capacity and enzymatic activity. As a model system, a RhM was conjugated to a redox enzyme, formate dehydrogenase obtained from Thiobacillus sp. KNK65MA (TsFDH. A RhM-containing azide group was site-specifically conjugated to p-azidophenylalanine introduced to a permissive site of TsFDH via a bioorthogonal strain-promoted azide-alkyne cycloaddition and an appropriate linker. The TsFDH-RhM conjugate exhibited retained cofactor regenerating capacity and enzymatic activity.

  5. Hydroxyl-radical-induced oxidation of cyclic dipeptides: Reactions of free peptide radicals and their peroxyl radicals

    International Nuclear Information System (INIS)

    Mieden, O.J.

    1989-01-01

    In the course of this study investigations were carried out into the reactions of hydroxyl radicals and hydrogen atoms with cyclic dipeptides as well as the subsequent reactions of peptide radicals and their peroxyl radicals in aqueous solution. The radiolysis products formed in the absence and presence of oxygen or transient metal complexes were characterized and determined on a quantitative basis. The linking of information from product analyses to the kinetic data for transient species obtained by time-resolving UV/VIS and conductivity measurements (pulse radiolysis) as well as computer-assisted simulations of individual events during the reaction permitted an evaluation of the mechanisms underlying the various processes and an identification of interim products with short life-times, which did or did not belong to the group of radicals. Through the characterization of key reactions of radicals and peroxyl radicals of this substance class a major advance has been made towards a better understanding of the role of radicals in the peptide compound and the mechanisms involved in indirect radiation effects on long-chain peptides and proteins. (orig.) [de

  6. Metal-catalyzed living radical polymerization and radical polyaddition for precision polymer synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, M; Satoh, K [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kamigaito, M, E-mail: kamigait@apchem.nagoya-u.ac.j

    2009-08-01

    The metal-catalyzed radical addition reaction can be evolved into two different polymerization mechanisms, i.e.; chain- and step-growth polymerizations, while both the polymerizations are based on the same metal-catalyzed radical formation reaction. The former is a widely employed metal-catalyzed living radical polymerization or atom transfer radical polymerization of common vinyl monomers, and the latter is a novel metal-catalyzed radical polyaddition of designed monomer with an unconjugated C=C double bond and a reactive C-Cl bond in one molecule. The simultaneous ruthenium-catalyzed living radical polymerization of methyl acrylate and radical polyaddition of 3-butenyl 2-chloropropionate was achieved with Ru(Cp*)Cl(PPh{sub 3}){sub 2} to afford the controlled polymers, in which the homopolymer segments with the controlled chain length were connected by the ester linkage.

  7. Cofactor of BRCA1: A new genetic marker for common malignant liver cancer

    Directory of Open Access Journals (Sweden)

    Editorial Office

    2016-08-01

    Full Text Available A new study has identified a vital gene in the pathogenesis and progression of liver cancer hepatocellular carcinoma (HCC, according to a team of biotechnology researchers at The American University in Cairo, Egypt, in a scientific paper published recently by AMOR. The study on human gene ‘Cofactor of BRCA1’ (dubbed COBRA1 and its potential role as a reliable cancer predictor for HCC is especially important due to the disease’s grim outlook. HCC is “ranked as the second most common cause of cancer-related deaths in the world in 2012,” the authors said. “Thus, it is considered as a highly aggressive cancer with poor prognosis,” they added. According to data from the Surveillance Epidemiology and End Results (SEER program, hepatocellular carcinoma accounts for 90% of all liver cancers worldwide. In the United States, HCC represents the fastest growing cause of cancer mortality overall and the second fastest growing cause of cancer deaths among women. Globally, the incidence of HCC in developing nations is over twice that of in developed countries – East Asia having highest incidence of HCC with the rate of 35 male cases per 100,000, followed by the continent of Africa. HCC mortality statistics in the developing countries is also more than double compared to the First World nations, with the annual loss of 33.5 and 23.73 lives per 100,000 in Asia and Africa, respectively. In addition, “HCC is usually diagnosed in the late stages of the tumor where, at some point, treatment is of limited efficacy. Thus, prognoses and follow-ups are necessary to regularly assess the patients and to predict any risks before the deterioration of patients’ condition,” said researcher Aya Youssef and her fellow team members. The behaviour of COBRA1 in the development and progression of several cancers has previously been studied and established, the researchers wrote. “For example, cell lines and tissues isolated from late-stage metastatic breast

  8. The crystal structure of escherichia coli MoaB suggests a probable role in molybdenum cofactor synthesis

    International Nuclear Information System (INIS)

    Sanishvili, R.; Beasley, S.; Skarina, T; Glesne, D; Joachimiak, A; Edwards, A; Savchenko, A.; Univ. Health Network; Univ. of Toronto

    2004-01-01

    The crystal structure of Escherichia coli MoaB was determined by multiwavelength anomalous diffraction phasing and refined at 1.6 Angstrom resolution. The molecule displayed a modified Rossman fold. MoaB is assembled into a hexamer composed of two trimers. The monomers have high structural similarity with two proteins, MogA and MoeA, from the molybdenum cofactor synthesis pathway in E. Coli, as well as with domains of mammalian gephyrin and plant Cnx1, which are also involved in molybdopterin synthesis. Structural comparison between these proteins and the amino acid conservation patterns revealed a putative active site in MoaB. The structural analysis of this site allowed to advance several hypothesis which can be tested in further studies

  9. Orgasmic Dysfunction after Radical Prostatectomy

    Directory of Open Access Journals (Sweden)

    Paolo Capogrosso

    2017-04-01

    Full Text Available In addition to urinary incontinence and erectile dysfunction, several other impairments of sexual function potentially occurring after radical prostatectomy (RP have been described; as a whole, these less frequently assessed disorders are referred to as neglected side effects. In particular, orgasmic dysfunctions (ODs have been reported in a non-negligible number of cases, with detrimental impacts on patients’ overall sexual life. This review aimed to comprehensively discuss the prevalence and physiopathology of post-RP ODs, as well as potential treatment options. Orgasm-associated incontinence (climacturia has been reported to occur in between 20% and 93% of patients after RP. Similarly, up to 19% of patients complain of postoperative orgasm-associated pain, mainly referred pain at the level of the penis. Moreover, impairment in the sensation of orgasm or even complete anorgasmia has been reported in 33% to 77% of patients after surgery. Clinical and surgical factors including age, the use of a nerve-sparing technique, and robotic surgery have been variably associated with the risk of ODs after RP, although robust and reliable data allowing for a proper estimation of the risk of postoperative orgasmic function impairment are still lacking. Likewise, little evidence regarding the management of postoperative ODs is currently available. In general, physicians should be aware of the prevalence of ODs after RP, in order to properly counsel all patients both preoperatively and immediately post-RP about the potential occurrence of bothersome and distressful changes in their overall sexual function.

  10. Orgasmic Dysfunction after Radical Prostatectomy

    Science.gov (United States)

    Ventimiglia, Eugenio; Cazzaniga, Walter; Montorsi, Francesco; Salonia, Andrea

    2017-01-01

    In addition to urinary incontinence and erectile dysfunction, several other impairments of sexual function potentially occurring after radical prostatectomy (RP) have been described; as a whole, these less frequently assessed disorders are referred to as neglected side effects. In particular, orgasmic dysfunctions (ODs) have been reported in a non-negligible number of cases, with detrimental impacts on patients' overall sexual life. This review aimed to comprehensively discuss the prevalence and physiopathology of post-RP ODs, as well as potential treatment options. Orgasm-associated incontinence (climacturia) has been reported to occur in between 20% and 93% of patients after RP. Similarly, up to 19% of patients complain of postoperative orgasm-associated pain, mainly referred pain at the level of the penis. Moreover, impairment in the sensation of orgasm or even complete anorgasmia has been reported in 33% to 77% of patients after surgery. Clinical and surgical factors including age, the use of a nerve-sparing technique, and robotic surgery have been variably associated with the risk of ODs after RP, although robust and reliable data allowing for a proper estimation of the risk of postoperative orgasmic function impairment are still lacking. Likewise, little evidence regarding the management of postoperative ODs is currently available. In general, physicians should be aware of the prevalence of ODs after RP, in order to properly counsel all patients both preoperatively and immediately post-RP about the potential occurrence of bothersome and distressful changes in their overall sexual function. PMID:28459142

  11. ORGASMIC FUNCTION AFTER RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    D. Yu. Pushkar

    2014-07-01

    Full Text Available Objective: to study orgasmic function (OF in patients undergoing radical prostatectomy (RPE.Subjects and methods. Seventy-nine patients who had undergone RPE for locally advanced prostate cancer without hormone and radiation therapies were examined. The patients’ mean age was 59.3 years. The mean EF-IIEF domain score was 24.4. OF was estimated by IIEF question 10 and the authors’ questionnaire. The Spearman rank correction coefficient and Mann-Whitney U-Wilcoxon tests were used.Results. After RPE, there was a reduction in the mean IIEF question 10 score from 3.9 (confidence interval 3.7–4.1 to 3.3 (3–3.5 (p = 0.000. The following changes were found in orgasm intensity: no changes in 43 %, mild worsening in 42 %, severe worsening in 8 %, and enhancement in 4 %; orgasm could not be achieved in 4 % of the patients. Pain usually of low intensity was reported by 8.8 %. The poor factors for preserving OF were its low baseline level, elderly age, or severe post-RPE erectile dysfunction.Conclusion. There were significant OF changes after RPE, which should be kept in mind while treating this category of patients.

  12. Specificity of anti-phospholipid antibodies in infectious mononucleosis: a role for anti-cofactor protein antibodies

    Science.gov (United States)

    Sorice, M; Pittoni, V; Griggi, T; Losardo, A; Leri, O; Magno, M S; Misasi, R; Valesini, G

    2000-01-01

    The antigen specificity of anti-phospholipid antibodies in infectious mononucleosis (IM) was studied using ELISA for the detection of anti-β2-glycoprotein I (β2-GPI), anti-annexin V, anti-protein S and anti-prothrombin antibodies and TLC immunostaining for the detection of anti-phospholipid antibodies. This technique enabled us to look at antibodies reacting to ‘pure’ phospholipid antigens in the absence of protein contamination. Sera from 46 patients with IM, 18 with systemic lupus erythematosus (SLE), 21 with primary anti-phospholipid antibody syndrome (PAPS), 50 with Helicobacter pylori infection and 30 healthy blood donors were tested. This study highlights anti-phospholipid antibodies in patients with IM as specific ‘pure’ anti-cardiolipin antibodies, while in PAPS and SLE patients anti-phosphatidylserine and anti-phosphatidylethanolamine antibodies were also found. This investigation also shows that the anti-cardiolipin antibodies found in IM can be present with anti-cofactor protein antibodies. The higher prevalence of anti-cofactor antibodies found in IM sera than in Helicobacter pylori sera may be due to the immunostimulatory effect and/or the polyclonal activation often observed in course of Epstein–Barr virus infection. However, anti-β2-GPI and, to a lesser extent, anti-prothrombin antibodies occur with a significantly lower prevalence in IM than in PAPS patients. This finding suggests that these antibodies should be regarded as the expression of the broad autoimmune syndrome involving the phospholipid-binding plasma proteins. PMID:10792380

  13. TcoF-DB: dragon database for human transcription co-factors and transcription factor interacting proteins

    KAUST Repository

    Schaefer, Ulf

    2010-10-21

    The initiation and regulation of transcription in eukaryotes is complex and involves a large number of transcription factors (TFs), which are known to bind to the regulatory regions of eukaryotic DNA. Apart from TF-DNA binding, protein-protein interaction involving TFs is an essential component of the machinery facilitating transcriptional regulation. Proteins that interact with TFs in the context of transcription regulation but do not bind to the DNA themselves, we consider transcription co-factors (TcoFs). The influence of TcoFs on transcriptional regulation and initiation, although indirect, has been shown to be significant with the functionality of TFs strongly influenced by the presence of TcoFs. While the role of TFs and their interaction with regulatory DNA regions has been well-studied, the association between TFs and TcoFs has so far been given less attention. Here, we present a resource that is comprised of a collection of human TFs and the TcoFs with which they interact. Other proteins that have a proven interaction with a TF, but are not considered TcoFs are also included. Our database contains 157 high-confidence TcoFs and additionally 379 hypothetical TcoFs. These have been identified and classified according to the type of available evidence for their involvement in transcriptional regulation and their presence in the cell nucleus. We have divided TcoFs into four groups, one of which contains high-confidence TcoFs and three others contain TcoFs which are hypothetical to different extents. We have developed the Dragon Database for Human Transcription Co-Factors and Transcription Factor Interacting Proteins (TcoF-DB). A web-based interface for this resource can be freely accessed at http://cbrc.kaust.edu.sa/tcof/ and http://apps.sanbi.ac.za/tcof/. © The Author(s) 2010.

  14. Thiamin diphosphate in biological chemistry: new aspects of thiamin metabolism, especially triphosphate derivatives acting other than as cofactors.

    Science.gov (United States)

    Bettendorff, Lucien; Wins, Pierre

    2009-06-01

    Prokaryotes, yeasts and plants synthesize thiamin (vitamin B1) via complex pathways. Animal cells capture the vitamin through specific high-affinity transporters essential for internal thiamin homeostasis. Inside the cells, thiamin is phosphorylated to higher phosphate derivatives. Thiamin diphosphate (ThDP) is the best-known thiamin compound because of its role as an enzymatic cofactor. However, in addition to ThDP, at least three other thiamin phosphates occur naturally in most cells: thiamin monophosphate, thiamin triphosphate (ThTP) and the recently discovered adenosine thiamin triphosphate. It has been suggested that ThTP has a specific neurophysiological role, but recent data favor a much more basic metabolic function. During amino acid starvation, Escherichia coli accumulate ThTP, possibly acting as a signal involved in the adaptation of the bacteria to changing nutritional conditions. In animal cells, ThTP can phosphorylate some proteins, but the physiological significance of this mechanism remains unknown. Adenosine thiamin triphosphate, recently discovered in E. coli, accumulates during carbon starvation and might act as an alarmone. Among the proteins involved in thiamin metabolism, thiamin transporters, thiamin pyrophosphokinase and a soluble 25-kDa thiamin triphosphatase have been characterized at the molecular level, in contrast to thiamin mono- and diphosphatases whose specificities remain to be proven. A soluble enzyme catalyzing the synthesis of adenosine thiamin triphosphate from ThDP and ADP or ATP has been partially characterized in E. coli, but the mechanism of ThTP synthesis remains elusive. The data reviewed here illustrate the complexity of thiamin biochemistry, which is not restricted to the cofactor role of ThDP.

  15. Putative endogenous filovirus VP35-like protein potentially functions as an IFN antagonist but not a polymerase cofactor.

    Directory of Open Access Journals (Sweden)

    Tatsunari Kondoh

    Full Text Available It has been proposed that some non-retroviral RNA virus genes are integrated into vertebrate genomes. Endogenous filovirus-like elements (EFLs have been discovered in some mammalian genomes. However, their potential roles in ebolavirus infection are unclear. A filovirus VP35-like element (mlEFL35 is found in the little brown bat (Myotis lucifugus genome. Putative mlEFL35-derived protein (mlEFL35p contains nearly full-length amino acid sequences corresponding to ebolavirus VP35. Ebola virus VP35 has been shown to bind double-stranded RNA, leading to inhibition of type I interferon (IFN production, and is also known as a viral polymerase cofactor that is essential for viral RNA transcription/replication. In this study, we transiently expressed mlEFL35p in human kidney cells and investigated its biological functions. We first found that mlEFL35p was coimmunoprecipitated with itself and ebolavirus VP35s but not with the viral nucleoprotein. Then the biological functions of mlEFL35p were analyzed by comparing it to ebolavirus VP35s. We found that the expression of mlEFL35p significantly inhibited human IFN-β promoter activity as well as VP35s. By contrast, expression of mlEFL35p did not support viral RNA transcription/replication and indeed slightly decrease the reporter gene expression in a minigenome assay. These results suggest that mlEFL35p potentially acts as an IFN antagonist but not a polymerase cofactor.

  16. Molybdenum cofactor deficiency causes translucent integument, male-biased lethality, and flaccid paralysis in the silkworm Bombyx mori.

    Science.gov (United States)

    Fujii, Tsuguru; Yamamoto, Kimiko; Banno, Yutaka

    2016-06-01

    Uric acid accumulates in the epidermis of Bombyx mori larvae and renders the larval integument opaque and white. Yamamoto translucent (oya) is a novel spontaneous mutant with a translucent larval integument and unique phenotypic characteristics, such as male-biased lethality and flaccid larval paralysis. Xanthine dehydrogenase (XDH) that requires a molybdenum cofactor (MoCo) for its activity is a key enzyme for uric acid synthesis. It has been observed that injection of a bovine xanthine oxidase, which corresponds functionally to XDH and contains its own MoCo activity, changes the integuments of oya mutants from translucent to opaque and white. This finding suggests that XDH/MoCo activity might be defective in oya mutants. Our linkage analysis identified an association between the oya locus and chromosome 23. Because XDH is not linked to chromosome 23 in B. mori, MoCo appears to be defective in oya mutants. In eukaryotes, MoCo is synthesized by a conserved biosynthesis pathway governed by four loci (MOCS1, MOCS2, MOCS3, and GEPH). Through a candidate gene approach followed by sequence analysis, a 6-bp deletion was detected in an exon of the B. mori molybdenum cofactor synthesis-step 1 gene (BmMOCS1) in the oya strain. Moreover, recombination was not observed between the oya and BmMOCS1 loci. These results indicate that the BmMOCS1 locus is responsible for the oya locus. Finally, we discuss the potential cause of male-biased lethality and flaccid paralysis observed in the oya mutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. TcoF-DB: dragon database for human transcription co-factors and transcription factor interacting proteins

    KAUST Repository

    Schaefer, Ulf; Schmeier, Sebastian; Bajic, Vladimir B.

    2010-01-01

    The initiation and regulation of transcription in eukaryotes is complex and involves a large number of transcription factors (TFs), which are known to bind to the regulatory regions of eukaryotic DNA. Apart from TF-DNA binding, protein-protein interaction involving TFs is an essential component of the machinery facilitating transcriptional regulation. Proteins that interact with TFs in the context of transcription regulation but do not bind to the DNA themselves, we consider transcription co-factors (TcoFs). The influence of TcoFs on transcriptional regulation and initiation, although indirect, has been shown to be significant with the functionality of TFs strongly influenced by the presence of TcoFs. While the role of TFs and their interaction with regulatory DNA regions has been well-studied, the association between TFs and TcoFs has so far been given less attention. Here, we present a resource that is comprised of a collection of human TFs and the TcoFs with which they interact. Other proteins that have a proven interaction with a TF, but are not considered TcoFs are also included. Our database contains 157 high-confidence TcoFs and additionally 379 hypothetical TcoFs. These have been identified and classified according to the type of available evidence for their involvement in transcriptional regulation and their presence in the cell nucleus. We have divided TcoFs into four groups, one of which contains high-confidence TcoFs and three others contain TcoFs which are hypothetical to different extents. We have developed the Dragon Database for Human Transcription Co-Factors and Transcription Factor Interacting Proteins (TcoF-DB). A web-based interface for this resource can be freely accessed at http://cbrc.kaust.edu.sa/tcof/ and http://apps.sanbi.ac.za/tcof/. © The Author(s) 2010.

  18. Structural basis of thermal stability of the tungsten cofactor synthesis protein MoaB from Pyrococcus furiosus.

    Directory of Open Access Journals (Sweden)

    Nastassia Havarushka

    Full Text Available Molybdenum and tungsten cofactors share a similar pterin-based scaffold, which hosts an ene-dithiolate function being essential for the coordination of either molybdenum or tungsten. The biosynthesis of both cofactors involves a multistep pathway, which ends with the activation of the metal binding pterin (MPT by adenylylation before the respective metal is incorporated. In the hyperthermophilic organism Pyrococcus furiosus, the hexameric protein MoaB (PfuMoaB has been shown to catalyse MPT-adenylylation. Here we determined the crystal structure of PfuMoaB at 2.5 Å resolution and identified key residues of α3-helix mediating hexamer formation. Given that PfuMoaB homologues from mesophilic organisms form trimers, we investigated the impact on PfuMoaB hexamerization on thermal stability and activity. Using structure-guided mutagenesis, we successfully disrupted the hexamer interface in PfuMoaB. The resulting PfuMoaB-H3 variant formed monomers, dimers and trimers as determined by size exclusion chromatography. Circular dichroism spectroscopy as well as chemical cross-linking coupled to mass spectrometry confirmed a wild-type-like fold of the protomers as well as inter-subunits contacts. The melting temperature of PfuMoaB-H3 was found to be reduced by more than 15 °C as determined by differential scanning calorimetry, thus demonstrating hexamerization as key determinant for PfuMoaB thermal stability. Remarkably, while a loss of activity at temperatures higher than 50 °C was observed in the PfuMoaB-H3 variant, at lower temperatures, we determined a significantly increased catalytic activity. The latter suggests a gain in conformational flexibility caused by the disruption of the hexamerization interface.

  19. User involvement competence for radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher

    2007-01-01

    -assisted navigation systems. The case study analysis reveals that firms who closely interact with specific users benefit significantly for their radical innovation work. These users have a high motivation toward new solutions, are open to new technologies, possess diverse competencies, and are embedded into a very......One important market related capability for firms which seek to develop radical innovations is the competence to involve the 'right' users at the 'right' time in the 'right' form. While former studies have identified a rather passive role of users in the radical innovation process, this paper...

  20. User involvement competence for radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher

    2007-01-01

    One important market related capability for firms which seek to develop radical innovations is the competence to involve the 'right' users at the 'right' time in the 'right' form. While former studies have identified a rather passive role of users in the radical innovation process, this paper......-assisted navigation systems. The case study analysis reveals that firms who closely interact with specific users benefit significantly for their radical innovation work. These users have a high motivation toward new solutions, are open to new technologies, possess diverse competencies, and are embedded into a very...

  1. Engineering a horseradish peroxidase C stable to radical attacks by mutating multiple radical coupling sites.

    Science.gov (United States)

    Kim, Su Jin; Joo, Jeong Chan; Song, Bong Keun; Yoo, Young Je; Kim, Yong Hwan

    2015-04-01

    Peroxidases have great potential as industrial biocatalysts. In particular, the oxidative polymerization of phenolic compounds catalyzed by peroxidases has been extensively examined because of the advantage of this method over other conventional chemical methods. However, the industrial application of peroxidases is often limited because of their rapid inactivation by phenoxyl radicals during oxidative polymerization. In this work, we report a novel protein engineering approach to improve the radical stability of horseradish peroxidase isozyme C (HRPC). Phenylalanine residues that are vulnerable to modification by the phenoxyl radicals were identified using mass spectrometry analysis. UV-Vis and CD spectra showed that radical coupling did not change the secondary structure or the active site of HRPC. Four phenylalanine (Phe) residues (F68, F142, F143, and F179) were each mutated to alanine residues to generate single mutants to examine the role of these sites in radical coupling. Despite marginal improvement of radical stability, each single mutant still exhibited rapid radical inactivation. To further reduce inactivation by radical coupling, the four substitution mutations were combined in F68A/F142A/F143A/F179A. This mutant demonstrated dramatic enhancement of radical stability by retaining 41% of its initial activity compared to the wild-type, which was completely inactivated. Structure and sequence alignment revealed that radical-vulnerable Phe residues of HPRC are conserved in homologous peroxidases, which showed the same rapid inactivation tendency as HRPC. Based on our site-directed mutagenesis and biochemical characterization, we have shown that engineering radical-vulnerable residues to eliminate multiple radical coupling can be a good strategy to improve the stability of peroxidases against radical attack. © 2014 Wiley Periodicals, Inc.

  2. Some reactions of oxidizing radicals with enzymes in aqueous solution

    International Nuclear Information System (INIS)

    Cundall, R.B.; Bisby, R.H.; Hoe, S.T.; Sims, H.E.; Anderson, R.F.

    1979-01-01

    A range of oxidizing radicals including some inorganic radical anions and the superoxide radical, can be generated by radiolysis of aqueous solutions. These radicals are more selective in their reactions with amino acids than the hydroxyl radical. Factors controlling the apparent reactivity of radical anions with proteins, such as free radical equilibria and ion-binding, are described. The superoxide radical inactivates papain by reaction with the cysteine residue. This reaction has been studied in solutions subjected to radiations of varying linear energy transfer. (Auth.)

  3. Radical pancreaticoduodenectomy for benign disease.

    LENUS (Irish Health Repository)

    Kavanagh, D O

    2008-01-01

    Whipple\\'s procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple\\'s procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple\\'s procedure during a 15-year period (1987-2002) were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%). One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30-75). The major presenting features included jaundice (five), pain (two), gastric outlet obstruction (one), and recurrent gastrointestinal haemorrhage (one). Investigations included ultrasound (eight), computerised tomography (eight), endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology), and endoscopic ultrasound (two). The pathological diagnosis included benign biliary stricture (two), chronic pancreatitis (two), choledochal cyst (one), inflammatory pseudotumour (one), cystic duodenal wall dysplasia (one), duodenal angiodysplasia (one), and granular cell neoplasm (one). There was no operative mortality. Morbidity included intra-abdominal collection (one), anastomotic leak (one), liver abscess (one), and myocardial infarction (one). All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple\\'s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound-guided fine needle aspirate (EUS-FNA) may reduce the need for Whipple\\'s operation

  4. Radical Pancreaticoduodenectomy for Benign Disease

    Directory of Open Access Journals (Sweden)

    D. O. Kavanagh

    2008-01-01

    Full Text Available Whipple's procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple's procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple's procedure during a 15-year period (1987–2002 were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%. One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30–75. The major presenting features included jaundice (five, pain (two, gastric outlet obstruction (one, and recurrent gastrointestinal haemorrhage (one. Investigations included ultrasound (eight, computerised tomography (eight, endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology, and endoscopic ultrasound (two. The pathological diagnosis included benign biliary stricture (two, chronic pancreatitis (two, choledochal cyst (one, inflammatory pseudotumour (one, cystic duodenal wall dysplasia (one, duodenal angiodysplasia (one, and granular cell neoplasm (one. There was no operative mortality. Morbidity included intra-abdominal collection (one, anastomotic leak (one, liver abscess (one, and myocardial infarction (one. All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple'’s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound–guided fine needle aspirate (EUS-FNA may reduce the need for Whipple's operation in

  5. Mechanism of the reaction of ebselen with endogenous thiols : dihydrolipoate is a better cofactor than glutathione in the peroxidase activity of ebselen

    NARCIS (Netherlands)

    Haenen, G R; De Rooij, B M; Vermeulen, N P; Bast, A

    The therapeutic effect of ebselen has been linked to its peroxidase activity. In the present study, the peroxidase activity of ebselen toward H2O2 with the endogenous thiols GSH and dihydrolipoate [L(SH)2] as cofactors was determined. When GSH was used, peroxide removal was described by a ter uni

  6. Relative contributions of decay accelerating factor (DAF), membrane cofactor protein (MCP) and CD59 in the protection of melanocytes from homologous complement

    NARCIS (Netherlands)

    Venneker, G. T.; Vodegel, R. M.; Okada, N.; Westerhof, W.; Bos, J. D.; Asghar, S. S.

    1998-01-01

    Complement regulatory molecules, membrane cofactor protein (MCP), decay accelerating factor (DAF) and CD59, protect body cells from autologous complement. They have wide tissue distribution but nothing is known about the expression of these molecules on human melanocytes. Since melanocytes are lysed

  7. Photodynamically generated bovine serum albumin radicals

    DEFF Research Database (Denmark)

    Silvester, J A; Timmins, G S; Davies, Michael Jonathan

    1998-01-01

    Porphyrin-sensitized photoxidation of bovine serum albumin (BSA) results in oxidation of the protein at (at least) two different, specific sites: the Cys-34 residue giving rise to a thiyl radical (RS.); and one or both of the tryptophan residues (Trp-134 and Trp-214) resulting in the formation...... of tertiary carbon-centred radicals and disruption of the tryptophan ring system. In the case of porphyrins such as hematoporphyrin, which bind at specific sites on BSA, these species appear to arise via long-range transfer of damage within the protein structure, as the binding site is some distance from...... the ultimate site of radical formation. This transfer of damage is shown to depend on a number of factors including the conformation of the protein, the presence of blocking groups and pH. Alteration of the protein conformation results in radical formation at additional (or alternative) sites, as does blocking...

  8. Radical production in the radiolysis of benzene

    International Nuclear Information System (INIS)

    LaVerne, J.A.; Araos, M.S.

    1998-01-01

    Complete text of publication follows. Benzene is the prototypical aromatic compound and yet the radiation chemistry of the radicals formed in its radiolysis is not well understood. Temporal information on the yield of phenyl radical, the major radical produced in the radiolysis, is important for understanding the radiation chemistry of many other types of aromatic compounds including some polymers. The effects of track structure on the production of phenyl radicals have been examined using iodine-scavenging techniques. The variation of the yields of iodobenzene and the other major molecular products such as biphenyl as a function of iodine concentration gives a good indication of the competition kinetics occurring in particle tracks. Experimental results of the scavenger experiments will be shown and their implications in the radiolysis of condensed hydrocarbons will be discussed

  9. Radical Sustainable Innovation of office buildings

    DEFF Research Database (Denmark)

    Koch, Christian; Berker, Thomas; Koch-Ørvad, Nina

    2017-01-01

    by high degrees of newness in the entire life cycle. RSI should offer significant enhancements of known benefits, entirely new benefits, or substantial cost reductions, leading to the transformation of existing markets, the creation of sustainable growth, and global sustainability. Thus, if buildings were....../could be radically new. How to evaluate radicality is a major challenge. It is tentatively proposed, to use standards for sustainable office buildings. Standards are developed to accelerate the sustainable development but has to some extent come to constrain possibilities of radical innovation. As the criteria...... of newness is incorporated in standards, going beyond them, could be viewed as radical. Empirically a selection of international cases of office buildings with very high scores of BREEAM, LEED and DGNB are examined. Six selected cases were analysed more in detail, one of them, Geelens...

  10. Interactions between simple radicals and water

    International Nuclear Information System (INIS)

    Crespo-Otero, Rachel; Sanchez-Garcia, Elsa; Suardiaz, Reynier; Montero, Luis A.; Sander, Wolfram

    2008-01-01

    The interactions of the simple radicals CH 3 , NH 2 , OH, and F with water have been studied by DFT (UB3LYP/6-311++G(2d,2p)) and ab initio (RHF-UCCSD(T)/6-311++G(2d,2p)) methods. In this order the number of lone pairs (from zero to three), the electronegativity, and the strength of the X-H bonds increase (X = C, N, and O). The various minima of the radical-water complexes were located using the multiple minima hypersurface (MMH) approach which had previously been proven to be useful for closed-shell molecules. The role of the unpaired electron in hydrogen bonding was investigated using the natural bond orbital (NBO) analysis. A considerable contribution of the unpaired electron to the complex stabilization was only found for the methyl radical and the fluorine atom, whereas in the aminyl and the hydroxyl radical the role of the unpaired electron is negligible

  11. Psychopathology according to behaviorism: a radical restatement.

    Science.gov (United States)

    Pérez-Alvarez, Marino

    2004-11-01

    This article is a radical restatement of the predominant psychopathology, which is characterized by nosological systems and by its approach towards a neurobiological conception of the so-called mental disorders. The "radical" sense of this restatement is that of radical behaviorism itself. As readers will recall, "radical" applied to behaviorism means total (not ignoring anything that interests psychology), pragmatic (referring to the practical sense of knowledge), and it also derives from the Latin word for "root" (and thus implies change beginning at a system's roots or getting to the root of things, in this case, of psychological disorders). Based on this, I introduce the Aristotelian distinction of material and form, which, besides being behaviorist avant la lettre, is used here as a critical instrument to unmask the hoax of psychopathology as it is presented. The implications of this restatement are discussed, some of them already prepared for clinical practice.

  12. Radical-Local Teaching and Learning

    DEFF Research Database (Denmark)

    Hedegaard, Mariane; Chaiklin, Seth

    radical-local teaching and learning approach. The first half of the book introduces the idea of radical-local teaching and learning and develops the theoretical background for this perspective, drawing on the cultural-historical research tradition, particularly from Vygotsky, El'konin, Davydov......, and Aidarova. The second half of the book addresses the central concern of radical-local teaching and learning - how to relate educational practices to children's specific historical and cultural conditions. The experiment was conducted for an academic year in an afterschool programme in the East Harlem......Radical-Local Teaching and Learning presents a theoretical perspective for analyzing and planning educational programmes for schoolchildren. To realize both general societal interests and worthwhile personal development, the content of educational programmes for children must be grounded...

  13. Prison Radicalization: The New Extremist Training Grounds?

    National Research Council Canada - National Science Library

    Coffin, Jr., McKinley D

    2007-01-01

    As a nation with the largest prison population in the world, the United States has all the ingredients for criminals, extremists, and religious radicals to collaborate in producing a new breed of homegrown terrorist...

  14. Neo-liberal Governing of 'Radicals'

    DEFF Research Database (Denmark)

    Lindekilde, Lasse

    2012-01-01

    The Danish government’s counter-radicalization Action Plan of 2009 had intended and unintended effects. Primarily targeting Danish Muslims, it employs neoliberal governmentality approaches of governance through individual support and response, information and knowledge, empowerment, surveillance...

  15. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Neumark, D.M. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  16. Catalytic surface radical in dye-decolorizing peroxidase: a computational, spectroscopic and site-directed mutagenesis study

    Science.gov (United States)

    Linde, Dolores; Pogni, Rebecca; Cañellas, Marina; Lucas, Fátima; Guallar, Victor; Baratto, Maria Camilla; Sinicropi, Adalgisa; Sáez-Jiménez, Verónica; Coscolín, Cristina; Romero, Antonio; Medrano, Francisco Javier; Ruiz-Dueñas, Francisco J.; Martínez, Angel T.

    2014-01-01

    Dye-decolorizing peroxidase (DyP) of Auricularia auricula-judae has been expressed in Escherichia coli as a representative of a new DyP family, and subjected to mutagenic, spectroscopic, crystallographic and computational studies. The crystal structure of DyP shows a buried haem cofactor, and surface tryptophan and tyrosine residues potentially involved in long-range electron transfer from bulky dyes. Simulations using PELE (Protein Energy Landscape Exploration) software provided several binding-energy optima for the anthraquinone-type RB19 (Reactive Blue 19) near the above aromatic residues and the haem access-channel. Subsequent QM/MM (quantum mechanics/molecular mechanics) calculations showed a higher tendency of Trp-377 than other exposed haem-neighbouring residues to harbour a catalytic protein radical, and identified the electron-transfer pathway. The existence of such a radical in H2O2-activated DyP was shown by low-temperature EPR, being identified as a mixed tryptophanyl/tyrosyl radical in multifrequency experiments. The signal was dominated by the Trp-377 neutral radical contribution, which disappeared in the W377S variant, and included a tyrosyl contribution assigned to Tyr-337 after analysing the W377S spectra. Kinetics of substrate oxidation by DyP suggests the existence of high- and low-turnover sites. The high-turnover site for oxidation of RB19 (kcat> 200 s−1) and other DyP substrates was assigned to Trp-377 since it was absent from the W377S variant. The low-turnover site/s (RB19 kcat ~20 s−1) could correspond to the haem access-channel, since activity was decreased when the haem channel was occluded by the G169L mutation. If a tyrosine residue is also involved, it will be different from Tyr-337 since all activities are largely unaffected in the Y337S variant. PMID:25495127

  17. Analysis of radicals of irradiated garlic

    International Nuclear Information System (INIS)

    Kameya, Hiromi; Kaimori, Yoshihiko; Ukai, Mitsuko

    2010-01-01

    The detection method of gamma ray irradiated garlic using Electron Spin Resonance(ESR)spectroscopy was studied. The ESR spectrum was consisted of one singlet signal at g=2.00. This signal is due to an organic free radical. Upon irradiation, the intensity of the signal was increased. Also two signals due to cellulose radical were detected nearby the singlet. The intensity of the singlet signal was increased as depend on the increase of the irradiation dose level. (author)

  18. Western radicalization: rethinking the psychology of terrorism

    OpenAIRE

    Pierson, Vern

    2017-01-01

    Approved for public release; distribution is unlimited The U.S. strategy to counter violent extremism relies heavily on the expert consensus that terrorists are engaging in political group speak and are by nature psychologically normal. Thus, anyone is susceptible to radicalization. To counter radicalization, finding answers is like finding a needle in a haystack. However, in the psychologically similar phenomenon of arson by firefighter—when a firefighter deliberately sets and then exting...

  19. Free radicals trapped in polyethylene matrix

    International Nuclear Information System (INIS)

    Shimada, S.; Maeda, M.; Hori, Y.; Kashiwabara, H.

    1977-01-01

    Two types of alkyl radicals were found to be trapped in irradiated crystals grown from polyethylene solution. One of them corresponds to the broad sextet pattern of the e.s.r. spectrum and the other corresponds to the sharp sextet pattern. The free radicals attributed to the broad sextet began to disappear at a lower temperature than the temperature at which the free radicals attributed to the sharp sextet disappeared. When butadiene molecules were brought into contact with the specimen, the decay of the free radicals corresponding to the broad sextet was accelerated. When the specimen was subjected to fuming nitric acid treatment, no broad sextet was observed. The mat of the crystals was aligned so that the c-axes of its crystallites were perpendicular to its surface. The broad sextet showed no anisotropy when the angle between the direction of applied magnetic field and that of the c-axis of the crystallite was varied. On the other hand, the sharp component of the spectrum showed apparent anisotropy. It can be concluded that the broad component comes from the free radicals trapped in the lamellar surface and the sharp component is attributed to the free radicals trapped in the inner part of the crystallite. (author)

  20. Radical and Not So Radical Transgressions: Invading Backstage Domains

    Directory of Open Access Journals (Sweden)

    Lada Čale Feldman

    2012-06-01

    Full Text Available Featuring as one of the privileged metaphors in humanities and social sciences, theatre provides primarily an image of a circumscribed space whose spatial syntax and modes of human engagement take place within and with respect to the larger space of the city, the world, and, as in Calderon’s Gran teatro del mundo, the universe. It is precisely as a special organization of spatiality that theatre reached the status of Foucault’s radical hetero-topos, flexible as it proved to be as a model for not only counter-representing all the human dealings in the external space, but also of conceptualizing, as in Freud’s psychoanalysis, man’s inner world, his psychic topography. But theatre is above all a concrete place, a built form with its own spatial history, its changing social and ideological functions, and its ways of bestowing to the bodies that enter into it actual or phantasm identities, thoughts, sensations, feelings and memories.My intervention will deal with one of the ruling borders/dichotomies/barriers of theatrical space, the one dividing “front stage” from “backstage” regions. In his detailed analysis of the latter in an individual and concrete theatre building, Andrew Filmer relies among others on Edward Soja’s “trialectics of being”, and thus also on Lefebvre’s categories of perceptual, conceptual and lived aspects of spatiality which Soja evokes, which will here be of particular interest. In contrast to the repercussions of such an analytical triad for the ethnographic study of concrete theatrical sites, I will ask how it pertains to potential manipulations of the aforementioned division of front-stage and backstage within contemporary performance practice. The temporal aspect of this manipulation should also be emphasized, having in mind the historical provenance of a whole backstage mythology – evidenced in numerous novels, plays and films situated in the backstage world - in the elaborated architectural

  1. Development of a new free radical absorption capacity assay method for antioxidants: aroxyl radical absorption capacity (ARAC).

    Science.gov (United States)

    Nagaoka, Shin-ichi; Nagai, Kanae; Fujii, Yuko; Ouchi, Aya; Mukai, Kazuo

    2013-10-23

    A new free radical absorption capacity assay method is proposed with use of an aroxyl radical (2,6-di-tert-butyl-4-(4'-methoxyphenyl)phenoxyl radical) and stopped-flow spectroscopy and is named the aroxyl radical absorption capacity (ARAC) assay method. The free radical absorption capacity (ARAC value) of each tocopherol was determined through measurement of the radical-scavenging rate constant in ethanol. The ARAC value could also be evaluated through measurement of the half-life of the aroxyl radical during the scavenging reaction. For the estimation of the free radical absorption capacity, the aroxyl radical was more suitable than the DPPH radical, galvinoxyl, and p-nitrophenyl nitronyl nitroxide. The ARAC value in tocopherols showed the same tendency as the free radical absorption capacities reported previously, and the tendency was independent of an oxygen radical participating in the scavenging reaction and of a medium surrounding the tocopherol and oxygen radical. The ARAC value can be directly connected to the free radical-scavenging rate constant, and the ARAC method has the advantage of treating a stable and isolable radical (aroxyl radical) in a user-friendly organic solvent (ethanol). The ARAC method was also successfully applied to a palm oil extract. Accordingly, the ARAC method would be useful in free radical absorption capacity assay of antioxidative reagents and foods.

  2. X-ray absorption spectroscopy on the calcium cofactor to the manganese cluster in photosynthetic oxygen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Cinco, Roehl M. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Along with Mn, calcium and chloride ions are necessary cofactors for oxygen evolution in Photosystem II (PS II). To further test and verify whether Ca is close to the Mn cluster, the authors substituted strontium for Ca and probed from the Sr point of view for any nearby Mn. The extended X-ray absorption fine structure (EXAFS) of Sr-reactivated PS II indicates major differences between the intact and NH2OH-treated samples. In intact samples, the Fourier transform of the Sr EXAFS shows a Fourier peak that is missing in inactive samples. This peak II is best simulated by two Mn neighbors at a distance of 3.5 Angstrom, confirming the proximity of Ca (Sr) cofactor to the Mn cluster. In addition, polarized Sr EXAFS on oriented Sr-reactivated samples shows this peak II is dichroic: large magnitude at 10 degrees (angle between the PS II membrane normal and the x-ray electric field vector) and small at 80 degrees. Analysis of the dichroism yields the relative angle between the Sr-Mn vector and membrane normal (23 degrees ± 4 degrees), and the isotropic coordination number for these layered samples. X-ray absorption spectroscopy has also been employed to assess the degree of similarity between the manganese cluster in PS II and a family of synthetic manganese complexes containing the distorted cubane [Mn4O3X] core (X = benzoate, acetate, methoxide, hydroxide, azide, fluoride, chloride or bromide). In addition, Mn4O3Cl complexes containing three or six terminal Cl ligands at three of the Mn were included in this study. The EXAFS method detects the small changes in the core structures as X is varied in this series, and serves to exclude these distorted cubanes of C3v symmetry as a topological model for the Mn catalytic cluster. The sulfur K-edge x-ray absorption near-edge structure (XANES) spectra for the amino acids cysteine, methionine, their corresponding oxidized forms cystine and methionine sulfoxide, and

  3. Free radicals in wood induced by γ-radiation

    International Nuclear Information System (INIS)

    Xu Honglin; Zhang Wenhui

    1994-01-01

    The free radicals in wood induced by γ-radiation were studied by electron spin resonance. The fine structure of the ESR signal from sawdust samples irradiated could be resolved into various radicals. These free radicals have a very long lifetime. The major spectrum for the free radicals will exponentially increased along with the radiation dose according to Y 1-Exp(-α a D). The intensity of radiation radicals is dependent on tree species. The stronger the intensity of mechanic free radicals is, the stronger the intensity of radiation free radicals

  4. HPLC-ESR techniques for detection of complex trapped radicals

    International Nuclear Information System (INIS)

    Tu Tiecheng; Dong Jirong; Lin Nianyun; Xie Leidong; Liu Rengzhong

    1992-01-01

    High performance liquid chromatography (HPLC) and ESR combined examination of radical species is an advanced techniques for separation and identification of complex radical species. At SRCL, Waters 990 HPLC has been used to separate the complex trapped radicals and Varian E-112 ESR spectrometer to record the spectra of single trapped radicals after HPLC separation. The advantages of the combined techniques are described as bellow: HPLC is used to separate the long-lived complex trapped radicals derived from reaction of short-lived radicals with spin trap. ESR spectra from single trapped radicals, obtained following HPLC separation of complex trapped radicals, are recorded one by one and well resolved. The structures of short-lived radicals can be inferred from the ESR spectra of the long-lived trapped radicals

  5. Why Nature Uses Radical SAM Enzymes so Widely: Electron Nuclear Double Resonance Studies of Lysine 2,3-Aminomutase Show the 5′-dAdo• “Free Radical” Is Never Free

    Science.gov (United States)

    Horitani, Masaki; Byer, Amanda S.; Shisler, Krista A.; Chandra, Tilak; Broderick, Joan B.; Hoffman, Brian M.

    2015-01-01

    Lysine 2,3-aminomutase (LAM) is a radical S-adenosyl-L-methionine (SAM) enzyme and, like other members of this superfamily, LAM utilizes radical-generating machinery comprising SAM anchored to the unique Fe of a [4Fe-4S] cluster via a classical five-membered N,O chelate ring. Catalysis is initiated by reductive cleavage of the SAM S–C5′ bond, which creates the highly reactive 5′-deoxyadenosyl radical (5′-dAdo•), the same radical generated by homolytic Co–C bond cleavage in B12 radical enzymes. The SAM surrogate S-3′,4′-anhydroadenosyl-L-methionine (anSAM) can replace SAM as a cofactor in the isomerization of L-α-lysine to L-β-lysine by LAM, via the stable allylic anhydroadenosyl radical (anAdo•). Here electron nuclear double resonance (ENDOR) spectroscopy of the anAdo• radical in the presence of 13C, 2H, and 15N-labeled lysine completes the picture of how the active site of LAM from Clostridium subterminale SB4 “tames” the 5′-dAdo• radical, preventing it from carrying out harmful side reactions: this “free radical” in LAM is never free. The low steric demands of the radical-generating [4Fe-4S]/SAM construct allow the substrate target to bind adjacent to the S–C5′ bond, thereby enabling the 5′-dAdo• radical created by cleavage of this bond to react with its partners by undergoing small motions, ~0.6 Å toward the target and ~1.5 Å overall, that are controlled by tight van der Waals contact with its partners. We suggest that the accessibility to substrate and ready control of the reactive C5′ radical, with “van der Waals control” of small motions throughout the catalytic cycle, is common within the radical SAM enzyme superfamily and is a major reason why these enzymes are the preferred means of initiating radical reactions in nature. PMID:25923449

  6. Synthesis and Characterization of Ethylenedithio-MPTTF-PTM Radical Dyad as a Potential Neutral Radical Conductor

    DEFF Research Database (Denmark)

    Souto, Manuel; Bendixen, Dan; Jensen, Morten

    2016-01-01

    During the last years there has been a high interest in the development of new purely-organic single-component conductors. Very recently, we have reported a new neutral radical conductor based on the perchlorotriphenylmethyl (PTM) radical moiety linked to a monopyrrolo-tetrathiafulvalene (MPTTF...

  7. How to counter radical narratives: Dutch deradicalization policy in the case of Moluccan and Islamic radicals

    NARCIS (Netherlands)

    Demant, F.; de Graaf, B.

    2010-01-01

    This article deals with the role of government in encouraging the decline of radical movements. The question posed is: "Which story can the government tell to encourage the decline of radical groups and the disengagement of their members?" The article makes use of the survey of factors promoting

  8. Reduction of quinones and phenoxy radicals by extracellular glucose dehydrogenase from Glomerella cingulata suggests a role in plant pathogenicity.

    Science.gov (United States)

    Sygmund, Christoph; Klausberger, Miriam; Felice, Alfons K; Ludwig, Roland

    2011-11-01

    The plant-pathogenic fungus Glomerella cingulata (anamorph Colletotrichum gloeosporoides) secretes high levels of an FAD-dependent glucose dehydrogenase (GDH) when grown on tomato juice-supplemented media. To elucidate its molecular and catalytic properties, GDH was produced in submerged culture. The highest volumetric activity was obtained in shaking flasks after 6 days of cultivation (3400 U l⁻¹, 4.2 % of total extracellular protein). GDH is a monomeric protein with an isoelectric point of 5.6. The molecular masses of the glycoforms ranged from 95 to 135 kDa, but after deglycosylation, a single 68 kDa band was obtained. The absorption spectrum is typical for an FAD-containing enzyme with maxima at 370 and 458 nm and the cofactor is non-covalently bound. The preferred substrates are glucose and xylose. Suitable electron acceptors are quinones, phenoxy radicals, 2,6-dichloroindophenol, ferricyanide and ferrocenium hexafluorophosphate. In contrast, oxygen turnover is very low. The GDH-encoding gene was cloned and phylogenetic analysis of the translated protein reveals its affiliation to the GMC family of oxidoreductases. The proposed function of this quinone and phenoxy radical reducing enzyme is to neutralize the action of plant laccase, phenoloxidase or peroxidase activities, which are increased in infected plants to evade fungal attack.

  9. Radical Transversal Lightlike Submanifolds of Indefinite Para-Sasakian Manifolds

    OpenAIRE

    Shukla S.S.; Yadav Akhilesh

    2014-01-01

    In this paper, we study radical transversal lightlike submanifolds and screen slant radical transversal lightlike submanifolds of indefinite para-Sasakian manifolds giving some non-trivial examples of these submanifolds. Integrability conditions of distributions D and RadTM on radical transversal lightlike submanifolds and screen slant radical transversal lightlike submanifolds of indefinite para-Sasakian manifolds, have been obtained. We also study totally contact umbilical radical transvers...

  10. Radical-Local Teaching and Learning

    DEFF Research Database (Denmark)

    Hedegaard, Mariane; Chaiklin, Seth

    Radical-Local Teaching and Learning presents a theoretical perspective for analyzing and planning educational programmes for schoolchildren. To realize both general societal interests and worthwhile personal development, the content of educational programmes for children must be grounded in the l......Radical-Local Teaching and Learning presents a theoretical perspective for analyzing and planning educational programmes for schoolchildren. To realize both general societal interests and worthwhile personal development, the content of educational programmes for children must be grounded...... radical-local teaching and learning approach. The first half of the book introduces the idea of radical-local teaching and learning and develops the theoretical background for this perspective, drawing on the cultural-historical research tradition, particularly from Vygotsky, El'konin, Davydov......, and Aidarova. The second half of the book addresses the central concern of radical-local teaching and learning - how to relate educational practices to children's specific historical and cultural conditions. The experiment was conducted for an academic year in an afterschool programme in the East Harlem...

  11. Radical-pair based avian magnetoreception

    Science.gov (United States)

    Procopio, Maria; Ritz, Thorsten

    2014-03-01

    Behavioural experiments suggest that migratory birds possess a magnetic compass sensor able to detect the direction of the geomagnetic. One hypothesis for the basis of this remarkable sensory ability is that the coherent quantum spin dynamics of photoinduced radical pair reactions transduces directional magnetic information from the geomagnetic field into changes of reaction yields, possibly involving the photoreceptor cryptochrome in the birds retina. The suggested radical-pair based avian magnetoreception has attracted attention in the field of quantum biology as an example of a biological sensor which might exploit quantum coherences for its biological function. Investigations on such a spin-based sensor have focussed on uncovering the design features for the design of a biomimetic magnetic field sensor. We study the effects of slow fluctuations in the nuclear spin environment on the directional signal. We quantitatively evaluate the robustness of signals under fluctuations on a timescale longer than the lifetime of a radical pair, utilizing two models of radical pairs. Our results suggest design principles for building a radical-pair based compass sensor that is both robust and highly directional sensitive.

  12. Vibronic Spectroscopy of the Phenylcyanomethyl Radical

    Science.gov (United States)

    Mehta, Deepali N.; Kidwell, Nathanael M.; Zwier, Timothy S.

    2011-06-01

    Resonance stabilized radicals (RSRs) are thought to be key intermediates in the formation of larger molecules in planetary atmospheres. Given the nitrogen-rich atmosphere of Titan, and the prevalence of nitriles there, it is likely that nitrile and isonitrile RSRs could be especially important in pathways leading to the formation of more complex nitrogen-containing compounds and the aerosols ("tholins") that are ultimately produced. In this talk, the results of a gas phase, jet-cooled vibronic spectroscopy study of the phenylcyanomethyl radical (C_6H_5.{C}HCN), the nitrogen-containing analog of the 1-phenylpropargyl radical, will be presented. A resonant two color photon ionization spectrum over the range 21,350-22,200 Cm-1 (450.0-468.0 nm) has been recorded, and the D_0-D_1 origin band has been tentatively identified at 21,400 Cm-1. Studies identifying the ionization threshold, and characterizing the vibronic structure will also be presented. An analogous study of the phenylisocyanomethyl radical, C_6H_5.{C}HNC, is currently being pursued for comparison with that of phenylcyanomethyl radical.

  13. Introducing Stable Radicals into Molecular Machines.

    Science.gov (United States)

    Wang, Yuping; Frasconi, Marco; Stoddart, J Fraser

    2017-09-27

    Ever since their discovery, stable organic radicals have received considerable attention from chemists because of their unique optical, electronic, and magnetic properties. Currently, one of the most appealing challenges for the chemical community is to develop sophisticated artificial molecular machines that can do work by consuming external energy, after the manner of motor proteins. In this context, radical-pairing interactions are important in addressing the challenge: they not only provide supramolecular assistance in the synthesis of molecular machines but also open the door to developing multifunctional systems relying on the various properties of the radical species. In this Outlook, by taking the radical cationic state of 1,1'-dialkyl-4,4'-bipyridinium (BIPY •+ ) as an example, we highlight our research on the art and science of introducing radical-pairing interactions into functional systems, from prototypical molecular switches to complex molecular machines, followed by a discussion of the (i) limitations of the current systems and (ii) future research directions for designing BIPY •+ -based molecular machines with useful functions.

  14. Analysis of radicals induced in irradiated foods

    International Nuclear Information System (INIS)

    Kishida, Keigo; Kaimori, Yoshihiko; Kawamura, Shoei; Sakamoto, Yuhki; Nakamura, Hideo; Ukai, Mitsuko; Kikuchi, Masahiro; Shimoyama, Yuhei; Kobayashi, Yasuhiko

    2012-01-01

    By electron spin resonance (ESR) spectroscopy, we revealed free radicals in γ-ray irradiated foods; black pepper, green coffee bean and ginseng. We also analyzed the decay behavior of radiation induced free radicals during storage of irradiated foods. The ESR spectrum of experimental irradiated foods consists of a sextet signal centered at g=2.0 and a singlet signal at the same g-value position and a singlet signal at g=4.0. The singlet signal at g=2.0 is originated from organic free radicals and its peak intensity showed the dependence of γ-ray irradiation dose levels. The signal intensity was decreased during storage. Only after 3 hours of radiation treatment the peak intensity was decreased fast and after that the intensity was decreased slowly. The relaxation times, T 1 and T 2 , of radiation induced free radicals showed the variations before and after irradiation. During long time storage period it was shown that T 1 was increased and T 2 was decreased. By analysis of decay process using the simulation methods based on the theory of reaction speed, it is considered that at least two kinds of radicals were induced in irradiated foods during long time storage. (author)

  15. Risk factors for human papillomavirus exposure and co-factors for cervical cancer in Latin America and the Caribbean.

    Science.gov (United States)

    Almonte, Maribel; Albero, Ginesa; Molano, Mónica; Carcamo, César; García, Patricia J; Pérez, Gonzalo

    2008-08-19

    The incidence of cervical cancer in Latin America and the Caribbean (LAC) is among the highest in the world. Because there are major demographic shifts happening in LAC countries (population growth, urbanization and ageing) cervical cancer incidence and mortality will likely continue to be a significant public health problem. Overall human papillomavirus (HPV) prevalence in the LAC general population has been found to be 2-fold higher than the average worldwide prevalence. The large HPV and cancer burden may be explained by the highly prevalent HPV variants of HPV types -16 and 18, which have an increased oncogenic potential. Given the major mode of transmission of genital HPV is sexual, certain, patterns of sexual behaviour (early age at first sexual intercourse, number of sexual partners and sexual behaviour of the partner) are associated with an increased risk of HPV genital acquisition. Although HPV infection is necessary for carcinogenesis, certain co-factors (high parity, long term use of oral contraceptives, smoking and co-infection with the human immunodeficiency virus (HIV)) help in the progression from infection to cancer. Many studies that have contributed to this evidence have been carried out in LAC and are reviewed and summarised in this article. Since HPV vaccines will likely take years to implement, and many more years to show impact on disease, cervical cancer screening programmes remain as the key intervention to control disease in LAC in the years to come.

  16. Development of CHARMM-Compatible Force-Field Parameters for Cobalamin and Related Cofactors from Quantum Mechanical Calculations.

    Science.gov (United States)

    Pavlova, Anna; Parks, Jerry M; Gumbart, James C

    2018-02-13

    Corrinoid cofactors such as cobalamin are used by many enzymes and are essential for most living organisms. Therefore, there is broad interest in investigating cobalamin-protein interactions with molecular dynamics simulations. Previously developed parameters for cobalamins are based mainly on crystal structure data. Here, we report CHARMM-compatible force field parameters for several corrinoids developed from quantum mechanical calculations. We provide parameters for corrinoids in three oxidation states, Co 3+ , Co 2+ , and Co 1+ , and with various axial ligands. Lennard-Jones parameters for the cobalt center in the Co(II) and Co(I) states were optimized using a helium atom probe, and partial atomic charges were obtained with a combination of natural population analysis (NPA) and restrained electrostatic potential (RESP) fitting approaches. The Force Field Toolkit was used to optimize all bonded terms. The resulting parameters, determined solely from calculations of cobalamin alone or in water, were then validated by assessing their agreement with density functional theory geometries and by analyzing molecular dynamics simulation trajectories of several corrinoid proteins for which X-ray crystal structures are available. In each case, we obtained excellent agreement with the reference data. In comparison to previous CHARMM-compatible parameters for cobalamin, we observe a better agreement for the fold angle and lower RMSD in the cobalamin binding site. The approach described here is readily adaptable for developing CHARMM-compatible force-field parameters for other corrinoids or large biomolecules.

  17. Discovery of cofactor-specific, bactericidal Mycobacterium tuberculosis InhA inhibitors using DNA-encoded library technology.

    Science.gov (United States)

    Soutter, Holly H; Centrella, Paolo; Clark, Matthew A; Cuozzo, John W; Dumelin, Christoph E; Guie, Marie-Aude; Habeshian, Sevan; Keefe, Anthony D; Kennedy, Kaitlyn M; Sigel, Eric A; Troast, Dawn M; Zhang, Ying; Ferguson, Andrew D; Davies, Gareth; Stead, Eleanor R; Breed, Jason; Madhavapeddi, Prashanti; Read, Jon A

    2016-12-06

    Millions of individuals are infected with and die from tuberculosis (TB) each year, and multidrug-resistant (MDR) strains of TB are increasingly prevalent. As such, there is an urgent need to identify novel drugs to treat TB infections. Current frontline therapies include the drug isoniazid, which inhibits the essential NADH-dependent enoyl-acyl-carrier protein (ACP) reductase, InhA. To inhibit InhA, isoniazid must be activated by the catalase-peroxidase KatG. Isoniazid resistance is linked primarily to mutations in the katG gene. Discovery of InhA inhibitors that do not require KatG activation is crucial to combat MDR TB. Multiple discovery efforts have been made against InhA in recent years. Until recently, despite achieving high potency against the enzyme, these efforts have been thwarted by lack of cellular activity. We describe here the use of DNA-encoded X-Chem (DEX) screening, combined with selection of appropriate physical properties, to identify multiple classes of InhA inhibitors with cell-based activity. The utilization of DEX screening allowed the interrogation of very large compound libraries (10 11 unique small molecules) against multiple forms of the InhA enzyme in a multiplexed format. Comparison of the enriched library members across various screening conditions allowed the identification of cofactor-specific inhibitors of InhA that do not require activation by KatG, many of which had bactericidal activity in cell-based assays.

  18. Relationship between intracellular pH, metabolic co-factors and caspase-3 activation in cancer cells during apoptosis.

    Science.gov (United States)

    Sergeeva, Tatiana F; Shirmanova, Marina V; Zlobovskaya, Olga A; Gavrina, Alena I; Dudenkova, Varvara V; Lukina, Maria M; Lukyanov, Konstantin A; Zagaynova, Elena V

    2017-03-01

    A complex cascade of molecular events occurs in apoptotic cells but cell-to-cell variability significantly complicates determination of the order and interconnections between different processes. For better understanding of the mechanisms of programmed cell death, dynamic simultaneous registration of several parameters is required. In this paper we used multiparameter fluorescence microscopy to analyze energy metabolism, intracellular pH and caspase-3 activation in living cancer cells in vitro during staurosporine-induced apoptosis. We performed metabolic imaging of two co-factors, NAD(P)H and FAD, and used the genetically encoded pH-indicator SypHer1 and the FRET-based sensor for caspase-3 activity, mKate2-DEVD-iRFP, to visualize these parameters by confocal fluorescence microscopy and two-photon fluorescence lifetime imaging microscopy. The correlation between energy metabolism, intracellular pH and caspase-3 activation and their dynamic changes were studied in CT26 cancer cells during apoptosis. Induction of apoptosis was accompanied by a switch to oxidative phosphorylation, cytosol acidification and caspase-3 activation. We showed that alterations in cytosolic pH and the activation of oxidative phosphorylation are relatively early events associated with the induction of apoptosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A disulfide-stabilized conformer of methionine synthase reveals an unexpected role for the histidine ligand of the cobalamin cofactor

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Supratim; Koutmos, Markos; Pattridge, Katherine A.; Ludwig, Martha L.; Matthews, Rowena G. (Michigan)

    2008-07-08

    B{sub 12}-dependent methionine synthase (MetH) from Escherichia coli is a large modular protein that is alternately methylated by methyltetrahydrofolate to form methylcobalamin and demethylated by homocysteine to form cob(I)alamin. Major domain rearrangements are required to allow cobalamin to react with three different substrates: homocysteine, methyltetrahydrofolate, and S-adenosyl-l-methionine (AdoMet). These same rearrangements appear to preclude crystallization of the wild-type enzyme. Disulfide cross-linking was used to lock a C-terminal fragment of the enzyme into a unique conformation. Cysteine point mutations were introduced at Ile-690 and Gly-743. These cysteine residues span the cap and the cobalamin-binding module and form a cross-link that reduces the conformational space accessed by the enzyme, facilitating protein crystallization. Here, we describe an x-ray structure of the mutant fragment in the reactivation conformation; this conformation enables the transfer of a methyl group from AdoMet to the cobalamin cofactor. In the structure, the axial ligand to the cobalamin, His-759, dissociates from the cobalamin and forms intermodular contacts with residues in the AdoMet-binding module. This unanticipated intermodular interaction is expected to play a major role in controlling the distribution of conformers required for the catalytic and the reactivation cycles of the enzyme.

  20. Cofactor balance by nicotinamide nucleotide transhydrogenase (NNT) coordinates reductive carboxylation and glucose catabolism in the tricarboxylic acid (TCA) cycle.

    Science.gov (United States)

    Gameiro, Paulo A; Laviolette, Laura A; Kelleher, Joanne K; Iliopoulos, Othon; Stephanopoulos, Gregory

    2013-05-03

    Cancer and proliferating cells exhibit an increased demand for glutamine-derived carbons to support anabolic processes. In addition, reductive carboxylation of α-ketoglutarate by isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) was recently shown to be a major source of citrate synthesis from glutamine. The role of NAD(P)H/NAD(P)(+) cofactors in coordinating glucose and glutamine utilization in the tricarboxylic acid (TCA) cycle is not well understood, with the source(s) of NADPH for the reductive carboxylation reaction remaining unexplored. Nicotinamide nucleotide transhydrogenase (NNT) is a mitochondrial enzyme that transfers reducing equivalents from NADH to NADPH. Here, we show that knockdown of NNT inhibits the contribution of glutamine to the TCA cycle and activates glucose catabolism in SkMel5 melanoma cells. The increase in glucose oxidation partially occurred through pyruvate carboxylase and rendered NNT knockdown cells more sensitive to glucose deprivation. Importantly, knocking down NNT inhibits reductive carboxylation in SkMel5 and 786-O renal carcinoma cells. Overexpression of NNT is sufficient to stimulate glutamine oxidation and reductive carboxylation, whereas it inhibits glucose catabolism in the TCA cycle. These observations are supported by an impairment of the NAD(P)H/NAD(P)(+) ratios. Our findings underscore the role of NNT in regulating central carbon metabolism via redox balance, calling for other mechanisms that coordinate substrate preference to maintain a functional TCA cycle.

  1. Shared Sulfur Mobilization Routes for tRNA Thiolation and Molybdenum Cofactor Biosynthesis in Prokaryotes and Eukaryotes

    Directory of Open Access Journals (Sweden)

    Silke Leimkühler

    2017-01-01

    Full Text Available Modifications of transfer RNA (tRNA have been shown to play critical roles in the biogenesis, metabolism, structural stability and function of RNA molecules, and the specific modifications of nucleobases with sulfur atoms in tRNA are present in pro- and eukaryotes. Here, especially the thiomodifications xm5s2U at the wobble position 34 in tRNAs for Lys, Gln and Glu, were suggested to have an important role during the translation process by ensuring accurate deciphering of the genetic code and by stabilization of the tRNA structure. The trafficking and delivery of sulfur nucleosides is a complex process carried out by sulfur relay systems involving numerous proteins, which not only deliver sulfur to the specific tRNAs but also to other sulfur-containing molecules including iron–sulfur clusters, thiamin, biotin, lipoic acid and molybdopterin (MPT. Among the biosynthesis of these sulfur-containing molecules, the biosynthesis of the molybdenum cofactor (Moco and the synthesis of thio-modified tRNAs in particular show a surprising link by sharing protein components for sulfur mobilization in pro- and eukaryotes.

  2. Expression of an Arabidopsis molybdenum cofactor sulphurase gene in soybean enhances drought tolerance and increases yield under field conditions.

    Science.gov (United States)

    Li, Yajun; Zhang, Jiachang; Zhang, Juan; Hao, Ling; Hua, Jinping; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu

    2013-08-01

    LOS5/ABA3 gene encoding molybdenum cofactor sulphurase is involved in aldehyde oxidase (AO) activity in Arabidopsis, which indirectly regulates ABA biosynthesis and increased stress tolerance. Here, we used a constitutive super promoter to drive LOS5/ABA3 overexpression in soybean (Glycine max L.) to enhance drought tolerance in growth chamber and field conditions. Expression of LOS5/ABA3 was up-regulated by drought stress, which led to increasing AO activity and then a notable increase in ABA accumulation. Transgenic soybean under drought stress had reduced water loss by decreased stomatal aperture size and transpiration rate, which alleviated leaf wilting and maintained higher relative water content. Exposed to drought stress, transgenic soybean exhibited reduced cell membrane damage by reducing electrolyte leakage and production of malondialdehyde and promoting proline accumulation and antioxidant enzyme activities. Also, overexpression of LOS5/ABA3 enhanced expression of stress-up-regulated genes. Furthermore, the seed yield of transgenic plants is at least 21% higher than that of wide-type plants under drought stress conditions in the field. These data suggest that overexpression of LOS5/ABA3 could improve drought tolerance in transgenic soybean via enhanced ABA accumulation, which could activate expression of stress-up-regulated genes and cause a series of physiological and biochemical resistant responses. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  3. Cooperation of decay-accelerating factor and membrane cofactor protein in regulating survival of human cervical cancer cells

    International Nuclear Information System (INIS)

    Gao, Ling-Juan; Guo, Shu-Yu; Cai, You-Qun; Gu, Ping-Qing; Su, Ya-Juan; Gong, Hui; Liu, Yun; Chen, Chen

    2009-01-01

    Decay-accelerating factor (DAF) and membrane cofactor protein (MCP) are the key molecules involved in cell protection against autologus complement, which restricts the action of complement at critical stages of the cascade reaction. The cooperative effect of DAF and MCP on the survival of human cervical cancer cell (ME180) has not been demonstrated. In this study we applied, for the first time, short hairpin RNA (shRNA) to knock down the expression of the DAF and MCP with the aim of exploiting complement more effectively for tumor cell damage. Meanwhile, we investigated the cooperative effects of DAF and MCP on the viability and migration, moreover the proliferation of ME180 cell. The results showed that shRNA inhibition of DAF and MCP expression enhanced complement-dependent cytolysis (CDC) up to 39% for MCP and up to 36% for DAF, and the combined inhibition of both regulators yielded further additive effects in ME180 cells. Thus, the activities of DAF and MCP, when present together, are greater than the sum of the two protein individually. These data indicated that combined DAF and MCP shRNA described in this study may offer an additional alternative to improve the efficacy of antibody-and complement-based cancer immunotherapy

  4. Vinylcyclopropylacyl and polyeneacyl radicals. Intramolecular ketene alkyl radical additions in ring synthesis.

    Science.gov (United States)

    De Boeck, Benoit; Herbert, Nicola M A; Harrington-Frost, Nicole M; Pattenden, Gerald

    2005-01-21

    Treatment of a variety of substituted vinylcyclopropyl selenyl esters, e.g. 11, with Bu(3)SnH-AIBN in refluxing benzene leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations via their ketene alkyl radical equivalents producing cyclohexenones in 50-60% yield. By contrast, treatment of conjugated triene selenyl esters, e.g. 32, with Bu(3)SnH-AIBN produces substituted 2-cyclopentenones via intramolecular cyclisations of their ketene alkyl radical intermediates. Under the same radical-initiating conditions the selenyl esters derived from o-vinylbenzoic acid and o-vinylcinnamic acid undergo intramolecular cyclisations producing 1-indanone and 5,6-dihydrobenzocyclohepten-7-one respectively in 60-70% yields. A tandem radical cyclisation from the alpha,beta,gamma,delta-diene selenyl ester 31 provides an expeditious synthesis of the diquinane 35 in 69% yield.

  5. Fragmentation characteristics of the unstable [CH3 CO][radical sign] radicals generated by neutralization of [CH3CO]+ cations

    Science.gov (United States)

    Hop, C. E. C. A.; Holmes, J. L.

    1991-03-01

    The stability and fragmentation characteristics of [CH3 CO][radical sign] radicals, generated by vertical charge exchange between acetyl cations and permanent gases or metal vapours (He, Xe, NO, Cd, Na and K), were examined mass spectrometrically. Two dissociation reactions were observed, the losses of CH[radical sign]3 and H[radical sign]. The H[radical sign] loss reaction, the higher energy dissociation, became of greater importance as the exothermicity of the charge exchange was increased. Based on the analysis of the kinetic energy releases it was concluded that these decompositions arose from the population of two excited states of the [CH3 CO][radical sign] radical.

  6. Time resolved resonance Raman spectra of anilino radical and aniline radical cation

    International Nuclear Information System (INIS)

    Tripathi, G.N.R.; Schuler, R.H.

    1987-01-01

    We report, in this paper, submicrosecond time resolved resonance Raman spectra of anilino radical and its radical cation as observed in pulse radiolytic studies of the oxidation of aniline in aqueous solution. By excitation in resonance with the broad and weak electronic transition of anilino radical at 400 nm (ε--1250 M -1 cm -1 ) we have observed, for the first time, the vibrational features of this radical. The Wilson ν 8 /sub a/ ring stretching mode at 1560 cm -1 is most strongly resonance enhanced. The ν 7 /sub a/ CN stretching band at 1505 cm -1 , which is shifted to higher frequency by 231 cm -1 with respect to aniline, is also prominent. The frequency of this latter mode indicates that the CN bond in the radical has considerable double bond character. The Raman spectrum of aniline radical cation, excited in resonance with the --425 nm electronic absorption (ε--4000 M -1 cm -1 ), shows features which are similar to phenoxyl radical. Most of the observed frequencies of this radical in solution are in good agreement with vibrational energies determined by recent laser photoelectron spectroscopic studies in the vapor phase. The bands most strongly enhanced in the resonance Raman spectrum are, however, weak in the photoelectron spectrum. While the vibrational frequencies observed for anilino radical and its isoelectronic cation are quite similar, the resonance enhancement patterns are very different. In particular the ν 14 b 2 mode of anilino radical observed at 1324 cm -1 is highly resonance enhanced because of strong vibronic coupling between the 400 nm 2 A 2 -- 2 B 1 and the higher 2 B 1 -- 2 B 1 electronic transitions

  7. Resveratrol products resulting by free radical attack

    Energy Technology Data Exchange (ETDEWEB)

    Bader, Yvonne; Quint, R.M. [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria)], E-mail: nikola.getoff@univie.ac.at

    2008-06-15

    Trans-resveratrol (trans-3,4',5-trihydroxystilbene; RES), which is contained in red wine and many plants, is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. Among other duties, RES has been reported to have anti-carcinogenetic activities, which could be attributed to its antioxidant properties. The degradation of RES was studied under various conditions. The products (aldehydes, carboxylic acids, etc.) generated from RES by the attack of free radicals were registered as a function of the radical concentration (absorbed radiation dose). Based on the obtained data it appears that the OH radicals are initiating the rather complicated process, which involves of the numerous consecutive reactions. A possible starting reaction mechanism is presented.

  8. Optimal pain management for radical prostatectomy surgery

    DEFF Research Database (Denmark)

    Joshi, Grish P; Jaschinski, Thomas; Bonnet, Francis

    2015-01-01

    BACKGROUND: Increase in the diagnosis of prostate cancer has increased the incidence of radical prostatectomy. However, the literature assessing pain therapy for this procedure has not been systematically evaluated. Thus, optimal pain therapy for patients undergoing radical prostatectomy remains...... controversial. METHODS: Medline, Embase, and Cochrane Central Register of Controlled Trials were searched for studies assessing the effects of analgesic and anesthetic interventions on pain after radical prostatectomy. All searches were conducted in October 2012 and updated in June 2015. RESULTS: Most...... treatments studied improved pain relief and/or reduced opioid requirements. However, there were significant differences in the study designs and the variables evaluated, precluding quantitative analysis and consensus recommendations. CONCLUSIONS: This systematic review reveals that there is a lack...

  9. Customers as Partners in Radical Service Innovation

    DEFF Research Database (Denmark)

    Scupola, Ada; Nicolajsen, Hanne Westh

    2009-01-01

      Purpose- The main purpose of this paper is to investigate customer involvement and related challenges in radical service innovations in engineering consulting services Design/methodology/approach - The paper uses a case study approach and so called rich descriptions to investigate customer...... involvement, roles and related challenges and conditions in radical service innovations.Findings- One main finding is that customers can engage in radical service innovations in engineering consultancy services and may play a decisive role. In doing this they most likely take on all the three user involvement...... roles defined in the literature of New Service and New Product Development. Also a number of conditions are found to be necessary in order for this collaboration to succeed. The conclusion is that another understanding and handling of the customer/supplier relation is needed along with a need...

  10. Radiation chemistry of aromatic dimer radical cations

    International Nuclear Information System (INIS)

    Okamoto, Kazumasa; Tagawa, Seiichi

    2009-01-01

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  11. Formation of stable radicals during perfluoroalkane radiolysis

    International Nuclear Information System (INIS)

    Allayarov, S.R.; Demidov, S.V.; Kiryukhin, D.P.; Mikhajlov, A.I.; Barkalov, I.M.

    1984-01-01

    Accumulation and stabilization kinetics of perfluoroalkyls during α-radiolysis ( 60 Co) of perfluoralkanes (PFA) in a wide temperature range for different PFA fractions differing in the average molecular weight, is investigated. It is noted that low temperature (PFA) radiolysis (77 K) is of a linear nature of accumulation of stabilized radicals up to doses of approximately 700 KGy. In the case of PFA radiolysis at 300 K radiation yields of stable radicals are somewhat lower than at 47 K and at doses of 200-300 KGy, their accumulation ceases. It is shown that kinetics of formation and accumulation of stable radicals does not depend on molecular mass and PFA fraction viscosity. Perfluoroalkyl stability is explained by intra molecular conformation spheric insulation of the free valency. Perfluoroalkyl stability in different PFA fractions in a wide time range in different media is investigated

  12. Hearing Status after Radical Mastoidectomy without Tympanoplasty.

    Science.gov (United States)

    Khan, Shamaila Nawaz; Udaipurwala, Iqbal Hussain; Mehmood, Talat; Rahat, Zahid Mehmood

    2017-12-01

    To find out the impairment of hearing associated with radical mastoidectomy by measuring the quantitative difference in the functional hearing level before and after radical mastoidectomy operation without tympanoplasty. Cross-sectional comparative study. Department of Otorhinolaryngology and Head Neck Surgery, Bahawal Victoria Hospital, Bahawalpur and PNS Shifa Hospital, Karachi, from November 2009 to January 2013. Eighty-five patients, diagnosed clinically as chronic suppurative otitis media with extensive cholesteatoma having history of ear discharge and hearing impairment for more than 6 weeks duration and requiring radical mastoidectomy for treatment, were included in this study. Pure tone audiogram was done before and after radical mastoidectomy. Hearing impairment was compared in each patient before and after the operation. Among the 85 patients, 54 (63.5%) were males and 31 (36.5%) were females, with the age ranged between 18 to 63 years, mean age being 42.31 4.8 years. The mean increase in hearing loss after radical mastoidectomy in air conduction was 7.19 dB, bone conduction was 4.16 dB, and air-bone gap was 3.75 dB (0.001). The ear became dry and safe in 82 patients (96.5%) out of a total of 85, and only 3 patients required revision surgery at a second stage. Radical mastoidectomy has a least negligible effect on hearing status and one should not limit this technique due to the concern of aggravated hearing in patients with extensive cholesteatoma at the cost of dry and safe ears, which should be of prime importance.

  13. Structures of Saccharomyces cerevisiae D-arabinose dehydrogenase Ara1 and its complex with NADPH: implications for cofactor-assisted substrate recognition.

    Science.gov (United States)

    Hu, Xiao-Qian; Guo, Peng-Chao; Ma, Jin-Di; Li, Wei-Fang

    2013-11-01

    The primary role of yeast Ara1, previously mis-annotated as a D-arabinose dehydrogenase, is to catalyze the reduction of a variety of toxic α,β-dicarbonyl compounds using NADPH as a cofactor at physiological pH levels. Here, crystal structures of Ara1 in apo and NADPH-complexed forms are presented at 2.10 and 2.00 Å resolution, respectively. Ara1 exists as a homodimer, each subunit of which adopts an (α/β)8-barrel structure and has a highly conserved cofactor-binding pocket. Structural comparison revealed that induced fit upon NADPH binding yielded an intact active-site pocket that recognizes the substrate. Moreover, the crystal structures combined with computational simulation defined an open substrate-binding site to accommodate various substrates that possess a dicarbonyl group.

  14. The structure of tubulin-binding cofactor A from Leishmania major infers a mode of association during the early stages of microtubule assembly

    Energy Technology Data Exchange (ETDEWEB)

    Barrack, Keri L.; Fyfe, Paul K.; Hunter, William N., E-mail: w.n.hunter@dundee.ac.uk [University of Dundee, Dow Street, Dundee DD1 5EH, Scotland (United Kingdom)

    2015-04-21

    The structure of a tubulin-binding cofactor from L. major is reported and compared with yeast, plant and human orthologues. Tubulin-binding cofactor A (TBCA) participates in microtubule formation, a key process in eukaryotic biology to create the cytoskeleton. There is little information on how TBCA might interact with β-tubulin en route to microtubule biogenesis. To address this, the protozoan Leishmania major was targeted as a model system. The crystal structure of TBCA and comparisons with three orthologous proteins are presented. The presence of conserved features infers that electrostatic interactions that are likely to involve the C-terminal tail of β-tubulin are key to association. This study provides a reagent and template to support further work in this area.

  15. Acute TNF-induced repression of cell identity genes is mediated by NFκB-directed redistribution of cofactors from super-enhancers

    DEFF Research Database (Denmark)

    Schmidt, Søren Fisker; Larsen, Bjørk Ditlev; Loft, Anne

    2015-01-01

    The proinflammatory cytokine tumor necrosis factor (TNF) plays a central role in low-grade adipose tissue inflammation and development of insulin resistance during obesity. In this context, nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) is directly involved and required for the...... specifically repressing super-enhancer-associated cell identity genes....... binding to the associated enhancers but rather loss of cofactors and enhancer RNA (eRNA) selectively from high-occupancy sites within super-enhancers. Based on these data, we have developed models that, with high accuracy, predict which enhancers and genes are repressed by TNF in adipocytes. We show...... that these models are applicable to other cell types where TNF represses genes associated with super-enhancers in a highly cell-type-specific manner. Our results propose a novel paradigm for NFκB-mediated repression, whereby NFκB selectively redistributes cofactors from high-occupancy enhancers, thereby...

  16. Exploring how lead users develop radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher; Gemuenden, Hans Georg; Hienerth, C.

    2008-01-01

    in order to transform their radically new solutions into functional prototypes and then to convince established manufacturers of the technological and market potential of their innovations. Using a comparative case study design in the high-tech field of medical equipment technology, we find that individual...... the supply of diversified knowledge, the development and coordination of a network for further development of the innovation, and initial tests of technical or market feasibility. Our findings have implications for manufacturing firms that wish to design radical innovation projects with (individual) lead...

  17. Preparation and study of dialkyl nitroxide radicals

    International Nuclear Information System (INIS)

    Chenavas, P.

    1969-01-01

    These radicals are obtained by oxidation of N-hydroxy-imides with lead tetracetate or p-nitro-perbenzoic acid. These imides are prepared by heating dicarboxylic acids anhydrides with benzyloxy-amine followed by catalytic hydrogenation of N-benzyloxy-imides so obtained. Two series of radicals have mainly been studied, the first concerning five-membered cyclic imides, the second six-membered cyclic imides, these molecules having methyls substituents or no on the carbon ring. N. M. R. spectra of some O-benzyl-imides have been analysed. These different results have made it possible to study the conformation and stereochemistry of these imides. (author) [fr

  18. RADICAL. Radiation information centre with analysing logic

    International Nuclear Information System (INIS)

    Rantanen, H.

    1998-01-01

    in an emergency, the production of data is overwhelming and the need of accurate and up-to-date information is essential. In Finland a new system (RADICAL) has been developed in order to automatically collect and maintain an overall view of the radiation situation and to facilitate the analysis of the consequences of any radiation incident. The project was started in the beginning of 1992 and the system was operational in summer 1994. The main objectives of the development process and how they are being fulfilled with the RADICAL system are discussed. (author)

  19. Dibromine radical anion reactions with heme enzymes

    International Nuclear Information System (INIS)

    Gebicka, L.; Gebicki, J.L.

    1996-01-01

    Reactions of Br 2 radical anion with heme enzymes, catalase horseradish peroxidase, have been studied by pulse radiolysis. It has been found that Br 2 - does not react with the heme centre of investigated enzymes. Dibromine radical anion reacts with tryptophan residues of catalase without any influence on the activity of catalase. It is suggested that in pulse radiolysis studies, where horseradish peroxidase is at about tenfold excess toward Br 2 - , the enzyme is modified rather by Br 2 , than by Br 2 - . (author). 26 refs., 3 figs

  20. Radical Islamism and Migrant Integration in Denmark

    DEFF Research Database (Denmark)

    Goli, Marco; Rezaei, Shahamak

    2011-01-01

    It has been suggested that alienation and failed integration may be causes of “Homegrown Radical Islamism” in Western societies. Western countries often expect that migrants and their descendants residing there as citizens will embrace or support common democratic ideals as a predicate for – or c......It has been suggested that alienation and failed integration may be causes of “Homegrown Radical Islamism” in Western societies. Western countries often expect that migrants and their descendants residing there as citizens will embrace or support common democratic ideals as a predicate...

  1. Resonance ionization detection of combustion radicals

    Energy Technology Data Exchange (ETDEWEB)

    Cool, T.A. [Cornell Univ., Ithaca, NY (United States)

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  2. Competing with the radical right: Distances between the European radical right and other parties on typical radical right issues

    NARCIS (Netherlands)

    Immerzeel, T.; Lubbers, M.; Coffé, H.

    2016-01-01

    The popularity of European Radical Right Populist parties (RRPs) has led to investigations into the distances between RRPs' and other parties' stances regarding immigration. This article adds to this literature by investigating the distance between RRPs and the other parties on a wider variety of

  3. Competing with the radical right. Distances between the European radical right and other parties on typical radical right issues

    NARCIS (Netherlands)

    Immerzeel, T.; Lubbers, M.; Coffe, H.R.

    2015-01-01

    The popularity of European Radical Right Populist parties (RRPs) has led to investigations into the distances between RRPs’ and other parties’ stances regarding immigration. This article adds to this literature by investigating the distance between RRPs and the other parties on a wider variety of

  4. Crystal Structure of the Thermus thermophilus 16 S rRNA Methyltransferase RsmC in Complex with Cofactor and Substrate Guanosine

    Energy Technology Data Exchange (ETDEWEB)

    Demirci, H.; Gregory, S; Dahlberg, A; Jogl, G

    2008-01-01

    Post-transcriptional modification is a ubiquitous feature of ribosomal RNA in all kingdoms of life. Modified nucleotides are generally clustered in functionally important regions of the ribosome, but the functional contribution to protein synthesis is not well understood. Here we describe high resolution crystal structures for the N{sup 2}-guanine methyltransferase RsmC that modifies residue G1207 in 16 S rRNA near the decoding site of the 30 S ribosomal subunit. RsmC is a class I S-adenosyl-l-methionine-dependent methyltransferase composed of two methyltransferase domains. However, only one S-adenosyl-l-methionine molecule and one substrate molecule, guanosine, bind in the ternary complex. The N-terminal domain does not bind any cofactor. Two structures with bound S-adenosyl-l-methionine and S-adenosyl-l-homocysteine confirm that the cofactor binding mode is highly similar to other class I methyltransferases. Secondary structure elements of the N-terminal domain contribute to cofactor-binding interactions and restrict access to the cofactor-binding site. The orientation of guanosine in the active site reveals that G1207 has to disengage from its Watson-Crick base pairing interaction with C1051 in the 16 S rRNA and flip out into the active site prior to its modification. Inspection of the 30 S crystal structure indicates that access to G1207 by RsmC is incompatible with the native subunit structure, consistent with previous suggestions that this enzyme recognizes a subunit assembly intermediate.

  5. Differential developmental expression of transcription factors GATA-4 and GATA-6, their cofactor FOG-2 and downstream target genes in testicular carcinoma in situ and germ cell tumors

    DEFF Research Database (Denmark)

    Salonen, Jonna; Rajpert-De Meyts, E; Mannisto, Susanna

    2010-01-01

    Testicular germ cell cancer is the most common malignancy among young males. The pre-invasive precursor, carcinoma in situ testis (CIS), presumably originates from arrested and transformed fetal gonocytes. Given that GATA transcription factors have essential roles in embryonic and testicular deve...... development, we explored the expression of GATA-4, GATA-6, cofactor friend of GATA (FOG)-2, and downstream target genes during human testis development and addressed the question whether changes in this pathway may contribute to germ cell neoplasms....

  6. Serum Hydroxyl Radical Scavenging Capacity as Quantified with Iron-Free Hydroxyl Radical Source

    Science.gov (United States)

    Endo, Nobuyuki; Oowada, Shigeru; Sueishi, Yoshimi; Shimmei, Masashi; Makino, Keisuke; Fujii, Hirotada; Kotake, Yashige

    2009-01-01

    We have developed a simple ESR spin trapping based method for hydroxyl (OH) radical scavenging-capacity determination, using iron-free OH radical source. Instead of the widely used Fenton reaction, a short (typically 5 seconds) in situ UV-photolysis of a dilute hydrogen peroxide aqueous solution was employed to generate reproducible amounts of OH radicals. ESR spin trapping was applied to quantify OH radicals; the decrease in the OH radical level due to the specimen’s scavenging activity was converted into the OH radical scavenging capacity (rate). The validity of the method was confirmed in pure antioxidants, and the agreement with the previous data was satisfactory. In the second half of this work, the new method was applied to the sera of chronic renal failure (CRF) patients. We show for the first time that after hemodialysis, OH radical scavenging capacity of the CRF serum was restored to the level of healthy control. This method is simple and rapid, and the low concentration hydrogen peroxide is the only chemical added to the system, that could eliminate the complexity of iron-involved Fenton reactions or the use of the pulse-radiolysis system. PMID:19794928

  7. Glutathione--hydroxyl radical interaction: a theoretical study on radical recognition process.

    Directory of Open Access Journals (Sweden)

    Béla Fiser

    Full Text Available Non-reactive, comparative (2 × 1.2 μs molecular dynamics simulations were carried out to characterize the interactions between glutathione (GSH, host molecule and hydroxyl radical (OH(•, guest molecule. From this analysis, two distinct steps were identified in the recognition process of hydroxyl radical by glutathione: catching and steering, based on the interactions between the host-guest molecules. Over 78% of all interactions are related to the catching mechanism via complex formation between anionic carboxyl groups and the OH radical, hence both terminal residues of GSH serve as recognition sites. The glycine residue has an additional role in the recognition of OH radical, namely the steering. The flexibility of the Gly residue enables the formation of further interactions of other parts of glutathione (e.g. thiol, α- and β-carbons with the lone electron pair of the hydroxyl radical. Moreover, quantum chemical calculations were carried out on selected GSH/OH(• complexes and on appropriate GSH conformers to describe the energy profile of the recognition process. The relative enthalpy and the free energy changes of the radical recognition of the strongest complexes varied from -42.4 to -27.8 kJ/mol and from -21.3 to 9.8 kJ/mol, respectively. These complexes, containing two or more intermolecular interactions, would be the starting configurations for the hydrogen atom migration to quench the hydroxyl radical via different reaction channels.

  8. Expression, purification, crystallization and preliminary phasing of the heteromerization domain of the tRNA-export and aminoacylation cofactor Arc1p from yeast

    International Nuclear Information System (INIS)

    Simader, Hannes; Suck, Dietrich

    2006-01-01

    The heteromerization domain of an aminoacyl-tRNA synthetase cofactor from yeast was crystallized, complete selenomethionine MAD data were collected to 2.8 Å resolution and preliminary phasing reveals the presence of 20 monomers in the asymmetric unit. Eukaryotic aminoacyl-tRNA synthetases (aaRSs) must be integrated into an efficient tRNA-export and shuttling machinery. This is reflected by the presence of additional protein–protein interaction domains and a correspondingly higher degree of complex formation in eukaryotic aaRSs. However, the structural basis of interaction between eukaryotic aaRSs and associated protein cofactors has remained elusive. The N-terminal heteromerization domain of the tRNA aminoacylation and export cofactor Arc1p has been cloned from yeast, expressed and purified. Crystals have been obtained belonging to space group C2, with unit-cell parameters a = 222.32, b = 89.46, c = 126.79 Å, β = 99.39°. Calculated Matthews coefficients are compatible with the presence of 10–25 monomers in the asymmetric unit. A complete multiple-wavelength anomalous dispersion data set has been collected from a selenomethionine-substituted crystal at 2.8 Å resolution. Preliminary phasing reveals the presence of 20 monomers organized in five tetramers per asymmetric unit

  9. Identification of an Isothiocyanate on the HypEF Complex Suggests a Route for Efficient Cyanyl-Group Channeling during [NiFe]-Hydrogenase Cofactor Generation.

    Directory of Open Access Journals (Sweden)

    Sven T Stripp

    Full Text Available [NiFe]-hydrogenases catalyze uptake and evolution of H2 in a wide range of microorganisms. The enzyme is characterized by an inorganic nickel/ iron cofactor, the latter of which carries carbon monoxide and cyanide ligands. In vivo generation of these ligands requires a number of auxiliary proteins, the so-called Hyp family. Initially, HypF binds and activates the precursor metabolite carbamoyl phosphate. HypF catalyzes removal of phosphate and transfers the carbamate group to HypE. In an ATP-dependent condensation reaction, the C-terminal cysteinyl residue of HypE is modified to what has been interpreted as thiocyanate. This group is the direct precursor of the cyanide ligands of the [NiFe]-hydrogenase active site cofactor. We present a FT-IR analysis of HypE and HypF as isolated from E. coli. We follow the HypF-catalyzed cyanation of HypE in vitro and screen for the influence of carbamoyl phosphate and ATP. To elucidate on the differences between HypE and the HypEF complex, spectro-electrochemistry was used to map the vibrational Stark effect of naturally cyanated HypE. The IR signature of HypE could ultimately be assigned to isothiocyanate (-N=C=S rather than thiocyanate (-S-C≡N. This has important implications for cyanyl-group channeling during [NiFe]-hydrogenase cofactor generation.

  10. Engineering Cofactor Preference of Ketone Reducing Biocatalysts: A Mutagenesis Study on a γ-Diketone Reductase from the Yeast Saccharomyces cerevisiae Serving as an Example

    Directory of Open Access Journals (Sweden)

    Michael Katzberg

    2010-04-01

    Full Text Available The synthesis of pharmaceuticals and catalysts more and more relies on enantiopure chiral building blocks. These can be produced in an environmentally benign and efficient way via bioreduction of prochiral ketones catalyzed by dehydrogenases. A productive source of these biocatalysts is the yeast Saccharomyces cerevisiae, whose genome also encodes a reductase catalyzing the sequential reduction of the γ-diketone 2,5-hexanedione furnishing the diol (2S,5S-hexanediol and the γ-hydroxyketone (5S-hydroxy-2-hexanone in high enantio- as well as diastereoselectivity (ee and de >99.5%. This enzyme prefers NADPH as the hydrogen donating cofactor. As NADH is more stable and cheaper than NADPH it would be more effective if NADH could be used in cell-free bioreduction systems. To achieve this, the cofactor binding site of the dehydrogenase was altered by site-directed mutagenesis. The results show that the rational approach based on a homology model of the enzyme allowed us to generate a mutant enzyme having a relaxed cofactor preference and thus is able to use both NADPH and NADH. Results obtained from other mutants are discussed and point towards the limits of rationally designed mutants.

  11. Acquisition of complement inhibitor serine protease factor I and its cofactors C4b-binding protein and factor H by Prevotella intermedia.

    Science.gov (United States)

    Malm, Sven; Jusko, Monika; Eick, Sigrun; Potempa, Jan; Riesbeck, Kristian; Blom, Anna M

    2012-01-01

    Infection with the Gram-negative pathogen Prevotella intermedia gives rise to periodontitis and a growing number of studies implies an association of P. intermedia with rheumatoid arthritis. The serine protease Factor I (FI) is the central inhibitor of complement degrading complement components C3b and C4b in the presence of cofactors such as C4b-binding protein (C4BP) and Factor H (FH). Yet, the significance of complement inhibitor acquisition in P. intermedia infection and FI binding by Gram-negative pathogens has not been addressed. Here we show that P. intermedia isolates bound purified FI as well as FI directly from heat-inactivated human serum. FI bound to bacteria retained its serine protease activity as shown in degradation experiments with (125)I-labeled C4b. Since FI requires cofactors for its activity we also investigated the binding of purified cofactors C4BP and FH and found acquisition of both proteins, which retained their activity in FI mediated degradation of C3b and C4b. We propose that FI binding by P. intermedia represents a new mechanism contributing to complement evasion by a Gram-negative bacterial pathogen associated with chronic diseases.

  12. Radical scavenging activity of crude polysaccharides from Camellia sinensis

    Directory of Open Access Journals (Sweden)

    Yang Fan

    2011-01-01

    Full Text Available A preparation of crude polysaccharides (TPS was isolated from Camellia sinensis by precipitation and ultrafiltration. TPS1, TPS2, and TPS3 had molecular weights of 240, 21.4, and 2.46 kDa, respectively. The radical scavenging activities of TPS were evaluated by DPPH free radical, hydroxyl radical and superoxide radical scavenging. These results revealed that TPS exhibited strong radical scavenging activity in a concentration-dependent manner. TPS3 with lowest molecular weight showed a higher radical scavenging activity.

  13. Understanding political radicalization: The two-pyramids model.

    Science.gov (United States)

    McCauley, Clark; Moskalenko, Sophia

    2017-04-01

    This article reviews some of the milestones of thinking about political radicalization, as scholars and security officials struggled after 9/11 to discern the precursors of terrorist violence. Recent criticism of the concept of radicalization has been recognized, leading to a 2-pyramids model that responds to the criticism by separating radicalization of opinion from radicalization of action. Security and research implications of the 2-pyramids model are briefly described, ending with a call for more attention to emotional experience in understanding both radicalization of opinion and radicalization of action. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  14. Interaction with the Redox Cofactor MYW and Functional Role of a Mobile Arginine in Eukaryotic Catalase-Peroxidase

    Science.gov (United States)

    2016-01-01

    Catalase-peroxidases (KatGs) are unique bifunctional heme peroxidases with an additional posttranslationally formed redox-active Met-Tyr-Trp cofactor that is essential for catalase activity. On the basis of studies of bacterial KatGs, controversial mechanisms of hydrogen peroxide oxidation were proposed. The recent discovery of eukaryotic KatGs with differing pH optima of catalase activity now allows us to scrutinize those postulated reaction mechanisms. In our study, secreted KatG from the fungus Magnaporthe grisea (MagKatG2) was used to analyze the role of a remote KatG-typical mobile arginine that was shown to interact with the Met-Tyr-Trp adduct in a pH-dependent manner in bacterial KatGs. Here we present crystal structures of MagKatG2 at pH 3.0, 5.5, and 7.0 and investigate the mobility of Arg461 by molecular dynamics simulation. Data suggest that at pH ≥4.5 Arg461 mostly interacts with the deprotonated adduct Tyr. Elimination of Arg461 by mutation to Ala slightly increases the thermal stability but does not alter the active site architecture or the kinetics of cyanide binding. However, the variant Arg461Ala lost the wild-type-typical optimum of catalase activity at pH 5.25 (kcat = 6450 s–1) but exhibits a broad plateau between pH 4.5 and 7.5 (kcat = 270 s–1 at pH 5.5). Moreover, significant differences in the kinetics of interconversion of redox intermediates of wild-type and mutant protein mixed with either peroxyacetic acid or hydrogen peroxide are observed. These findings together with published data from bacterial KatGs allow us to propose a role of Arg461 in the H2O2 oxidation reaction of KatG. PMID:27293030

  15. Functional analysis of the interaction of the human immunodeficiency virus type 1 Rev nuclear export signal with its cofactors

    International Nuclear Information System (INIS)

    Kiss, A.; Li, L.; Gettemeier, T.; Venkatesh, L.K.

    2003-01-01

    Human immunodeficiency virus type 1 (HIV-1) Rev-mediated nuclear export of viral RNAs involves the interaction of its leucine-rich nuclear export sequence (NES) with nuclear cofactors. In yeast two-hybrid screens of a human lymph node derived cDNA expression library, we identified the human nucleoporin Nup98 as a highly specific and potent interactor of the Rev NES. Using an extensive panel of nuclear export positive and negative mutants of the functionally homologous NESs of the HIV-1 Rev, human T cell leukemia virus type 1 (HTLV-1) Rex, and equine infectious anemia virus (EIAV) Rev proteins, physiologically significant interaction of hNup98 with the various NESs was demonstrated. Missense mutations in the yeast nuclear export factor Crm1p that abrogated Rev NES interaction with the XXFG repeat-containing nucleoporin, Rab/hRIP, had minimal effects on the interaction of GLFG repeat-containing hNup98. Functional analysis of Nup98 domains required for nuclear localization demonstrated that the entire ORF was required for efficient incorporation into the nuclear envelope. A putative nuclear localization signal was identified downstream of the GLFG repeat region. Whereas overexpression of both full-length Nup98 and the amino-terminal GLFG repeat region, but not the unique carboxy-terminal region, induced significant suppression of HIV unspliced RNA export, lower levels of exogenous Nup98 expression resulted in a relatively modest increase in unspliced RNA export. These results suggest a physiological role for hNup98 in modulating Rev-dependent RNA export during HIV infection

  16. Structural rearrangements occurring upon cofactor binding in the Mycobacterium smegmatis β-ketoacyl-acyl carrier protein reductase MabA.

    Science.gov (United States)

    Küssau, Tanja; Flipo, Marion; Van Wyk, Niel; Viljoen, Albertus; Olieric, Vincent; Kremer, Laurent; Blaise, Mickaël

    2018-05-01

    In mycobacteria, the ketoacyl-acyl carrier protein (ACP) reductase MabA (designated FabG in other bacteria) catalyzes the NADPH-dependent reduction of β-ketoacyl-ACP substrates to β-hydroxyacyl-ACP products. This first reductive step in the fatty-acid biosynthesis elongation cycle is essential for bacteria, which makes MabA/FabG an interesting drug target. To date, however, very few molecules targeting FabG have been discovered and MabA remains the only enzyme of the mycobacterial type II fatty-acid synthase that lacks specific inhibitors. Despite the existence of several MabA/FabG crystal structures, the structural rearrangement that occurs upon cofactor binding is still not fully understood. Therefore, unlocking this knowledge gap could help in the design of new inhibitors. Here, high-resolution crystal structures of MabA from Mycobacterium smegmatis in its apo, NADP + -bound and NADPH-bound forms are reported. Comparison of these crystal structures reveals the structural reorganization of the lid region covering the active site of the enzyme. The crystal structure of the apo form revealed numerous residues that trigger steric hindrance to the binding of NADPH and substrate. Upon NADPH binding, these residues are pushed away from the active site, allowing the enzyme to adopt an open conformation. The transition from an NADPH-bound to an NADP + -bound form is likely to facilitate release of the product. These results may be useful for subsequent rational drug design and/or for in silico drug-screening approaches targeting MabA/FabG.

  17. Can the United States Defeat Radical Islam

    Science.gov (United States)

    2008-05-22

    It strongly disapproves of idolatry, the popular cult of saints and tomb visitation. 11...twentieth century, Sayyid Qutb (1906-1966), an Egyptian Islamic radical, referencing al-Wahhab, developed a modified concept of jahiliyya. In Qutb’s...It strongly disapproves of idolatry, the popular cult of saints and tomb visitation. When ibn Taymiyya was asked if the murderous. Mongols, who

  18. Identity and Islamic Radicalization in Western Europe

    NARCIS (Netherlands)

    S.M. Murshed (Syed); S. Pavan (Sara)

    2009-01-01

    textabstractThis paper argues that both socio-economic disadvantage and political factors, such as the West’s foreign policy with regard to the Muslim world, along with historical grievances, play a part in the development of Islamic radicalized collective action in Western Europe. We emphasise the

  19. Lipophilic fluorescent products of free radicals

    Czech Academy of Sciences Publication Activity Database

    Ivica, Josko; Wilhelm, Jiří

    2014-01-01

    Roč. 158, č. 3 (2014), s. 365-372 ISSN 1213-8118 R&D Projects: GA ČR(CZ) GAP303/11/0298 Institutional support: RVO:67985823 Keywords : lipofuscin-like pigments * lipid peroxidation * free radical s * fluorescence Subject RIV: CE - Biochemistry Impact factor: 1.200, year: 2014

  20. Radical Negativity: Music Education for Social Justice

    Science.gov (United States)

    McLaren, Peter

    2011-01-01

    According to Hedges (2010), the real enemies of the liberal class are radical thinkers such as Noam Chomsky and Ralph Nader, iconoclastic intellectuals who possess the moral autonomy to defy the power elite. While this author agrees with Hedges, he would take this argument even further. In this article, the author argues that the real enemy of…

  1. Unimolecular reaction dynamics of free radicals

    International Nuclear Information System (INIS)

    Terry A. Miller

    2006-01-01

    Free radical reactions are of crucial importance in combustion and in atmospheric chemistry. Reliable theoretical models for predicting the rates and products of these reactions are required for modeling combustion and atmospheric chemistry systems. Unimolecular reactions frequently play a crucial role in determining final products. The dissociations of vinyl, CH2= CH, and methoxy, CH3O, have low barriers, about 13,000 cm-1 and 8,000 cm-1, respectively. Since barriers of this magnitude are typical of free radicals these molecules should serve as benchmarks for this important class of reactions. To achieve this goal, a detailed understanding of the vinyl and methoxy radicals is required. Results for dissociation dynamics of vinyl and selectively deuterated vinyl radical are reported. Significantly, H-atom scrambling is shown not to occur in this reaction. A large number of spectroscopic experiments for CH3O and CHD2O have been performed. Spectra recorded include laser induced fluorescence (LIF), laser excited dispersed fluorescence (LEDF), fluorescence dip infrared (FDIR) and stimulated emission pumping (SEP). Such results are critical for implementing dynamics experiments involving the dissociation of methoxy

  2. Neglected Side Effects After Radical Prostatectomy

    DEFF Research Database (Denmark)

    Frey, Anders Ullmann; Sønksen, Jens; Fode, Mikkel

    2014-01-01

    INTRODUCTION: A series of previously neglected sexually related side effects to radical prostatectomy (RP) has been identified over the recent years. These include orgasm-associated incontinence (OAI), urinary incontinence in relation to sexual stimulation (UISS), altered perception of orgasm, or...

  3. Letter: OCCO*+, NNCO*+ and NNNN*+ radical cations.

    Science.gov (United States)

    Flammang, R; Srinivas, R; Nguyen, M T; Gerbaux, P

    2007-01-01

    Chemical ionization of a mixture of nitrogen and carbon monoxide produces three stable isobaric species at m/z 56: OCCO, OCNN and NNNN radical cations. Separated at increased resolution, these ions are readily identified by collisional activation. Neutralization-reionization experiments performed on two different mass spectrometers have not allowed the detection of any recovery signals for the corresponding neutrals.

  4. Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic ...

    African Journals Online (AJOL)

    Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic Profile of Methanol Extracts of Wild Plants of Southern Sonora, Mexico. EF Moran-Palacio, LA Zamora-Álvarez, NA Stephens-Camacho, GA Yáñez- Farías, A Virgen-Ortiz, O Martínez-Cruz, JA Rosas-Rodríguez ...

  5. Quantification of Radicals Generated in a Sonicator

    Directory of Open Access Journals (Sweden)

    Kassim Badmus

    2016-06-01

    Full Text Available The hydroxyl radical (OH• is a powerful oxidant produced as a consequence of cavitation in water. It can react nonspecifically in breaking down persistent organic pollutants in water into their mineral form. It can also recombine to form hydrogen peroxide which is very useful in water treatment. In this study, terephthalic acid (TA and potassium iodide dosimetry were used to quantify and investigate the behaviour of the generated OH radical in a laboratory scale sonicator. The 2-hydroxyl terephthalic acid (HTA formed during terephthalic acid dosimetry was determined by optical fibre spectrometer. The production rate of HTA served as a means of evaluating and characterizing the OH• generated over given time in a sonicator. The influence of sonicator power intensity, solution pH and irradiation time upon OH• generation were investigated. Approximately 2.2 ´ 10-9 M s-1 of OH radical was generated during the sonication process. The rate of generation of the OH radicals was established to be independent of the concentration of the initial reactant. Thus, the rate of generation of OH• can be predicted by zero order kinetics in a sonicator.

  6. Parents’ Perspectives on Radicalization: A Qualitative Study

    NARCIS (Netherlands)

    E. Sikkens (Elga); M.R.P.J.R.S. van San (Marion); S. Sieckelinck (Stijn); M. de Winter (Micha)

    2018-01-01

    textabstractAbstract: Radicalization of young people might be influenced by the way parents react towards the development of political or religious ideals. However, these reactions have hardly been explored. This study aimed to discover how parents reacted to the development of extreme ideals, and

  7. Radical Feminism and the Subject of Writing.

    Science.gov (United States)

    Rhodes, Jacqueline

    The radical feminists of the late 1960s and early 1970s, as well as their online counterparts today, offer provocative examples of networked textuality, a discourse dependent on the constant and visible contextualization of self and writing within the discourses of hegemony. Given its potential use for liberatory writing pedagogies, it seems…

  8. Formation of radical cations of diaryloxadiazoles

    International Nuclear Information System (INIS)

    Helmstreit, W.

    1988-01-01

    The nature of the formation of the radical cation of the 2,5-bis-(p-diethylaminophenyl)-1,3,4-oxadiazole (PC) in liquid n-butyl chloride and acetonitrile has been investigated by observing excited state fluorescence and transient absorption using nanosecond pulse radiolysis and laser flash photolysis. The formation of solute oxonium ions has also been observed. At concentrations -4 mol dm -3 the growth time at which the transient absorption of the radical cation reaches the maximum follows the rise time of the electron pulse ( 2 laser yields the solute radical cation in an acetonitrile solution of 2 x 10 -4 mol dm -3 PC via an electronically excited state. Here, the generation time was smaller than 5 ns. The yield of the cation is increased by addition of CCl 4 . A reaction mechanism is proposed that explains the fast cation formation in terms of an exciplex formed by interaction between an electronically excited state of diaryloxadiazole and the ground state of the solvent. This exciplex yields the solute radical cation. (author)

  9. Albert Einstein: Radical Pacifist and Democrat

    Science.gov (United States)

    Jayaraman, T.

    We draw attention here to the radical political grounding of Einstein's pacifism. We also drescribe some less commonly known aspects of his commitment to civil liberties, particularly in the context of the anti-l hysteria and anti-racism current in the United States of the late 1940s and 1950s. We also examine briefly his views on socialism.

  10. Phytochemical screening, free radical scavenging and antibacterial ...

    African Journals Online (AJOL)

    Cassia sieberiana is a tropical plant, widely distributed throughout Sudan and Guinea savannah. It is used in traditional medicine for the treatment of malarial, cancer and stomach ache. The study was conducted to screen for phytochemicals, free radical scavenging and antibacterial potentials of the root bark.

  11. Radicals derived from acetaldehyde and vinyl alcohol.

    Science.gov (United States)

    Estep, Marissa L; Morgan, W James; Winkles, Alexander T; Abbott, Adam S; Villegas-Escobar, Nery; Mullinax, J Wayne; Turner, Walter E; Wang, Xiao; Turney, Justin M; Schaefer, Henry F

    2017-10-18

    Vinyl alcohol and acetaldehyde are isoelectronic products of incomplete butanol combustion. Along with the radicals resulting from the removal of atomic hydrogen or the hydroxyl radical, these species are studied here using ab initio methods as complete as coupled cluster theory with single, double, triple, and perturbative quadruple excitations [CCSDT(Q)], with basis sets as large as cc-pV5Z. The relative energies provided herein are further refined by including corrections for relativistic effects, the frozen core approximation, and the Born-Oppenheimer approximation. The effects of anharmonic zero-point vibrational energies are also treated. The syn conformer of vinyl alcohol is predicted to be lower in energy than the anti conformer by 1.1 kcal mol -1 . The alcoholic hydrogen of syn-vinyl alcohol is found to be the easiest to remove, requiring 84.4 kcal mol -1 . Five other radicals are also carefully considered, with four conformers investigated for the 1-hydroxyvinyl radical. Beyond energetics, we have conducted an overhaul of the spectroscopic literature for these species. Our results also provide predictions for fundamental modes yet to be reported experimentally. To our knowledge, the ν 3 (3076 cm -1 ) and ν 4 (2999 cm -1 ) C-H stretches for syn-vinyl alcohol and all but one of the vibrational modes for anti-vinyl alcohol (ν 1 -ν 14 ) are yet to be observed experimentally. For the acetyl radical, ν 6 (1035 cm -1 ), ν 11 (944 cm -1 ), ν 12 (97 cm -1 ), and accounting for our changes to the assignment of the 1419.9 cm -1 experimental mode, ν 10 (1441 cm -1 ), are yet to be observed. We have predicted these unobserved fundamentals and reassigned the experimental 1419.9 cm -1 frequency in the acetyl radical to ν 4 rather than to ν 10 . Our work also strongly supports reassignment of the ν 10 and ν 11 fundamentals of the vinoxy radical. We suggest that the bands assigned to the overtones of these fundamentals were in fact combination bands. Our

  12. Pertinent issues related to laparoscopic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Sidney C. Abreu

    2003-12-01

    Full Text Available PURPOSE: We describe the critical steps of the laparoscopic radical prostatectomy (LRP technique and discuss how they impact upon the pertinent issues regarding prostate cancer surgery: blood loss, potency and continence. RESULTS: A major advantage of LRP is the reduced operative blood loss. The precise placement of the dorsal vein complex stitch associated with the tamponading effect of the CO2 pneumoperitoneum significantly decrease venous bleeding, which is the main source of blood loss during radical prostatectomy. At the Cleveland Clinic, the average blood loss of our first 100 patients was 322.5 ml, resulting in low transfusion rates. The continuous venous bleeding narrowed pelvic surgical field and poor visibility can adversely impact on nerve preservation during open radical prostatectomy. Laparoscopy, with its enhanced and magnified vision in a relatively bloodless field allows for excellent identification and handling of the neurovascular bundles. During open retropubic radical prostatectomy, the pubic bone may impair visibility and access to the urethral stump, and the surgeon must tie the knots relying on tactile sensation alone. Consequently, open prostatectomy is associated with a prolonged catheterization period of 2 - 3 weeks. Comparatively, during laparoscopic radical prostatectomy all sutures are meticulously placed and each is tied under complete visual control, resulting in a precise mucosa-to-mucosa approximation. CONCLUSION: The laparoscopic approach may represent a reliable less invasive alternative to the conventional open approach. Despite the encouraging preliminary anatomical and functional outcomes, prospective randomized comparative trials are required to critically evaluate the role of laparoscopy for this sophisticated and delicate operation.

  13. Multiple free-radical scavenging capacity in serum

    Science.gov (United States)

    Oowada, Shigeru; Endo, Nobuyuki; Kameya, Hiromi; Shimmei, Masashi; Kotake, Yashige

    2012-01-01

    We have developed a method to determine serum scavenging-capacity profile against multiple free radical species, namely hydroxyl radical, superoxide radical, alkoxyl radical, alkylperoxyl radical, alkyl radical, and singlet oxygen. This method was applied to a cohort of chronic kidney disease patients. Each free radical species was produced with a common experimental procedure; i.e., uv/visible-light photolysis of free-radical precursor/sensitizer. The decrease in free-radical concentration by the presence of serum was quantified with electron spin resonance spin trapping method, from which the scavenging capacity was calculated. There was a significant capacity change in the disease group (n = 45) as compared with the healthy control group (n = 30). The percent values of disease’s scavenging capacity with respect to control group indicated statistically significant differences in all free-radical species except alkylperoxyl radical, i.e., hydroxyl radical, 73 ± 12% (p = 0.001); superoxide radical, 158 ± 50% (p = 0.001); alkoxyl radical, 121 ± 30% (p = 0.005); alkylperoxyl radical, 123 ± 32% (p>0.1); alkyl radical, 26 ± 14% (p = 0.001); and singlet oxygen, 57 ± 18% (p = 0.001). The scavenging capacity profile was illustrated using a radar chart, clearly demonstrating the characteristic change in the disease group. Although the cause of the scavenging capacity change by the disease state is not completely understood, the profile of multiple radical scavenging capacities may become a useful diagnostic tool. PMID:22962529

  14. TRANSITION METAL CATALYSIS IN CONTROLLED RADICAL POLYMERIZATION: ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    Science.gov (United States)

    Novel and diversified macromolecular structures, which include polymers with designed topologies (top), compostions (middle), and functionalities (bottom), can be prepared by atom transfer radical polymerization processes. These polymers can be synthesized from a large variety of...

  15. Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons

    International Nuclear Information System (INIS)

    Barnabas, M.V.; Trifunac, A.D.

    1994-01-01

    Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by γ-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations

  16. Glutathione as a radical scavenger and the biological consequences of thiyl radical production

    International Nuclear Information System (INIS)

    Winterbourn, C.C.

    1996-01-01

    A large number of compounds that have toxic effects can be metabolised to free radicals and secondary reactive oxygen species. These may be directly damaging or affect cell function by altering regulatory mechanisms through changing redox status. Protection is provided by an integrated system of antioxidant defenses. This includes reduced glutathione (GSH), one of the functions of which is as a free radical scavenger. For GSH to be an effective radical scavenging antioxidant, therefore, it must act in concert with superoxide dismutase to remove the superoxide so generated. Superoxide is produced in a variety of metabolic processes. It is also a secondary product of radicals reacting with oxygen either directly or through GSH. The biological reactivity of superoxide has been the subject of much debate ever since the discovery of superoxide dismutase in 1968. It has more recently become apparent that its rapid reaction with nitric oxide to give peroxynitrite, and its ability to reversibly oxidise and inactivate iron sulphur enzymes, contribute to the toxicity of superoxide. Another mechanism that could be important involves addition reactions of superoxide with other radicals to give organic peroxides. This reaction, to form a tyrosine peroxide, has come to authors attention through the study of the scavenging of tyrosyl radicals by GSH. It is also shown that a tyrosine peroxide is a major product of the oxidation of tyrosine by neutrophils

  17. Radical surgery compared with intracavitary cesium followed by radical surgery in cervical carcinoma stage IB

    Energy Technology Data Exchange (ETDEWEB)

    Tinga, D.J.; Bouma, J.; Aalders, J.G. (Dept. of Obstetrics and Gynaecology, State Univ. Hospital, Groningen (Netherlands)); Hollema, H. (Dept. of Pathology, State Univ. Hospital, Groningen (Netherlands))

    1990-01-01

    Forty-nine patients aged {le} 45 years, with cervical carcinoma stage IB ({le} 3 cm) were treated with either primary radical surgery (n = 26), or intracavitary irradiation followed by radical surgery (n = 23). With primary surgery, ovarian function had been preserved in 15 of the 25 patients, who were alive and well. Seven of the primary surgery patients were irradiated postoperatively and 2 others with a central recurrence were cured by irradiation. One other patient, who was not irradiated postoperatively, had an intestinal metastasis and died of the disease. If any of the adverse prognostic factors (as reported in the literature) had been considered as an indication for postoperative irradiation, 17 patients instead of 7 would have been irradiated after primary radical surgery. In the comparable group of 23 patients treated by intracavitary irradiation and radical surgery (and in 4 cases postoperative irradiation as well) there was no recurrence. There was no significant statistical difference between the treatment results in the cesium + surgery group and those who underwent primary radical surgery. Young patients with early cervical carcinoma without prognostic indicators for postoperative irradiation can benefit from primary radical surgery, because their ovarian function can be preserved. (authors).

  18. Radical surgery compared with intracavitary cesium followed by radical surgery in cervical carcinoma stage IB

    International Nuclear Information System (INIS)

    Tinga, D.J.; Bouma, J.; Aalders, J.G.; Hollema, H.

    1990-01-01

    Forty-nine patients aged ≤ 45 years, with cervical carcinoma stage IB (≤ 3 cm) were treated with either primary radical surgery (n = 26), or intracavitary irradiation followed by radical surgery (n = 23). With primary surgery, ovarian function had been preserved in 15 of the 25 patients, who were alive and well. Seven of the primary surgery patients were irradiated postoperatively and 2 others with a central recurrence were cured by irradiation. One other patient, who was not irradiated postoperatively, had an intestinal metastasis and died of the disease. If any of the adverse prognostic factors (as reported in the literature) had been considered as an indication for postoperative irradiation, 17 patients instead of 7 would have been irradiated after primary radical surgery. In the comparable group of 23 patients treated by intracavitary irradiation and radical surgery (and in 4 cases postoperative irradiation as well) there was no recurrence. There was no significant statistical difference between the treatment results in the cesium + surgery group and those who underwent primary radical surgery. Young patients with early cervical carcinoma without prognostic indicators for postoperative irradiation can benefit from primary radical surgery, because their ovarian function can be preserved. (authors)

  19. Pyrimidine nucleobase radical reactivity in DNA and RNA

    Science.gov (United States)

    Greenberg, Marc M.

    2016-11-01

    Nucleobase radicals are major products of the reactions between nucleic acids and hydroxyl radical, which is produced via the indirect effect of ionizing radiation. The nucleobase radicals also result from hydration of cation radicals that are produced via the direct effect of ionizing radiation. The role that nucleobase radicals play in strand scission has been investigated indirectly using ionizing radiation to generate them. More recently, the reactivity of nucleobase radicals resulting from formal hydrogen atom or hydroxyl radical addition to pyrimidines has been studied by independently generating the reactive intermediates via UV-photolysis of synthetic precursors. This approach has provided control over where the reactive intermediates are produced within biopolymers and facilitated studying their reactivity. The contributions to our understanding of pyrimidine nucleobase radical reactivity by this approach are summarized.

  20. Isoflurane preconditions myocardium against infarction via release of free radicals

    NARCIS (Netherlands)

    Müllenheim, Jost; Ebel, Dirk; Frässdorf, Jan; Preckel, Benedikt; Thämer, Volker; Schlack, Wolfgang

    2002-01-01

    BACKGROUND: Isoflurane exerts cardioprotective effects that mimic the ischemic preconditioning phenomenon. Generation of free radicals is implicated in ischemic preconditioning. The authors investigated whether isoflurane-induced preconditioning may involve release of free radicals. METHODS:

  1. Mechanism of protection of adenosine from sulphate radical anion ...

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Repair by caffeic acid; repair of adenosine radicals; oxidation by sulphate radical anions. ... known that hydroxycinnamic acids are natural anti- oxidants ... acid. 2. Experimental ..... ously and independently under kinetic conditions at.

  2. Free Radical Scavenging Properties of Annona squamosa

    Science.gov (United States)

    Vikas, Biba; Akhil B, S; P, Remani; Sujathan, K

    2017-10-26

    Annona squamosa has extensively been used in the traditional and folkloric medicine and found to possess many biological activities. Different solvents, petroleum ether, chloroform, ethyl acetate and methanol extracts of Annona squamosa seeds (ASPE, ASCH, ASEA, ASME) have been used to prepare plant extracts. The present investigations dealt with the free radical scavenging activity of four extracts using various techniques such as total reducing power estimation, total phenolic count, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging effect, evaluation of ABTS cation decolorisation capacity, FRAP assay, hdroxyl radical scavenging assay, super oxide assay and Nitric oxide radical scavenging assay of the extracts. The results showed that the four extracts of Annona squamosa showed significant reducing power in four extracts. The total phenolic contents in petroleum ether, chloroform, ethyl acetate, methanol extracts and positive control were 0.64±0.17, 0.54±0.27, 0.49±0.24, 0.57±0.22 and 0.66±0.33. The antioxidant capacity by ABTS assay of ASPE, ASCH, ASEA, ASME and positive control, trolox showed 77.75±0.5,73.25±1.7,78.5± 1.2 , 80 ± 0.8 μg/ml and 94.2 ± 0.9 respectively. The (50 % scavenging activity) SA50 of ASPE and ASCH, ASEA and ASME was found to be 34.4 μg/ml, 43.8 μg/ml 34.7 μg/m and 28.8 μg/ml respectively by DPPH assay. The percentage of hydroxyl radical scavenging increased with the increasing concentration of the extracts. ASPE, ASCH, ASEA and ASME showed superoxide radical scavenging activity, as indicated by their values 66 ± 0.5, 68 ± 1 ,63 ± 1 and 70 ± 0.5 μg/ml respectively compared to gallic acid which was 97 ± 0.5 μg/ml. The values for scavenging of nitric oxide for ASPE, ASCH, ASEA and ASME were 91.0 ± 1.0, 66.75 ± 0.5, 71.75 ± 1.1 and 75.75 ± 1.15 μg/ml while value for standard ascorbic acid was 91.0 ± 1.0 μg/ml. The results revealed strong antioxidants in four extracts may lead to the development of potent

  3. Leadership Styles for the Five Stages of Radical Change

    Science.gov (United States)

    1998-04-01

    radical change. This article continues prior work on radical change with theory and research on leadership style. The result is a model of radical...every stage of that process. Leadership style and organiza- tional change theory and re- search have ex- isted for de- cades, but have rarely con...phase, inspire and en- ergize them to adopt the change after it Figure 3. Senior Manager Leadership Styles for the Five Phases of Radical Change Phase

  4. Superoxide radical (O2-) reactivity with respect to glutathione

    International Nuclear Information System (INIS)

    Sekaki, A.; Gardes-Albert, M.; Ferradini, C.

    1984-01-01

    Influence of superoxide radicals formed during gamma irradiation of glutathione in aerated aqueous solutions is examined. Solutions are buffered at pH7 and contain sodium formate for capture of H and OH radicals which are transformed in COO - radicals and then O 2 - radicals. G value of glutathione disparition vs glutathione concentration are given with and without enzyme or catalase. Reaction mechanism are interpreted [fr

  5. Radical transfer between proteins: role of tyrosine, tryptophan and protein peroxyl radicals

    International Nuclear Information System (INIS)

    Irwin, J.A.; Ostdal, H.; Davies, M.J.

    1998-01-01

    Reaction of the Fe(III) forms of the heme proteins myoglobin (Mb) and horseradish peroxidase (HRP) with H 2 O 2 gives rise to high-oxidation-state heme-derived species which can be described as a Fe(IV)-oxo porphyrin radical-cation ('Compound 1'). In the case of Mb, the Fe(IV)-oxo porphyrin radical-cation undergoes rapid electron transfer with the surrounding protein to give protein (globin)-derived radicals and an Fe(lV)-oxo species ('Compound 2'). The globin-derived radicals have been shown to be located at two (or more) sites: Tyr-103 or Trp-14, with the latter radical known to react with oxygen to give a Trp-derived peroxyl radical (Mb-Trp-OO*). With HRP, the Fe(lV)-oxo porphyrin radical-cation carries out two successive one-electron oxidation reactions at the exposed heme edge to give firstly 'Compound 2' [the Fe(lV)oxo species] and then the resting Fe(III) state of the enzyme. n this study we have investigated whether the Trp-14 peroxyl radical from Mb and the Compound 1 and 2 species from HRP (in the absence and presence of free Tyr) can oxidise amino acids, peptides and proteins. Such reactions constitute intermolecular protein-to-protein radical transfer reactions and hence protein chain-oxidation. We have also examined whether these oxidants react with antioxidants. Reaction of these heme-protein derived oxidants with amino acids, proteins and antioxidants has been carried out at room temperature for defined periods of time before freeze-quenching to 77K to halt reaction. The radical species present in the reaction system at the time of freezing were subsequently examined by EPR spectroscopy at 77K. Three free amino acids, Tyr, Trp and Cys (with Cys the least efficient) have been shown to react rapidly with Mb-Trp-OO*, as evidenced by the loss of the characteristic EPR features of Mb-Trp-OO* on inclusion of increasing concentrations of the amino acids. All other amino acids are much less reactive. Evidence has also been obtained for (inefficient) hydrogen

  6. Hybrid radical energy storage device and method of making

    Science.gov (United States)

    Gennett, Thomas; Ginley, David S; Braunecker, Wade; Ban, Chunmei; Owczarczyk, Zbyslaw

    2015-01-27

    Hybrid radical energy storage devices, such as batteries or electrochemical devices, and methods of use and making are disclosed. Also described herein are electrodes and electrolytes useful in energy storage devices, for example, radical polymer cathode materials and electrolytes for use in organic radical batteries.

  7. Responsibility for radical change in addressing climate change

    NARCIS (Netherlands)

    Bouvrie, des N.; Karlsson-Vinkhuyzen, S.I.S.E.; Jollands, N.

    2015-01-01

    To radically address the problem of climate change, it is not enough to modify specific attitudes and behaviors while upholding the present paradigms. This article aims to show why modifications will never bring about radical carbon emission reductions. We discuss what it implies to desire radical

  8. Biochemistry and pathology of radical-mediated protein oxidation

    DEFF Research Database (Denmark)

    Dean, R T; Fu, S; Stocker, R

    1997-01-01

    Radical-mediated damage to proteins may be initiated by electron leakage, metal-ion-dependent reactions and autoxidation of lipids and sugars. The consequent protein oxidation is O2-dependent, and involves several propagating radicals, notably alkoxyl radicals. Its products include several catego...

  9. Enhancing production through optimisation of DPPH and radical ...

    African Journals Online (AJOL)

    ... of dry matter for DPPH radical scavenging activity. Methanol had the lowest value (78 mg g-1 dry matter) for polyphenol extracts and 80 mg g-1 for the DPPH radical scavenging activity. The main extract compounds were gallic acid, catechin and epicatechin. Key Words: High density lipids, polyphenol, radical scavenging ...

  10. Radical radiotherapy for T3 laryngeal cancers

    International Nuclear Information System (INIS)

    Uno, T.; Itami, J.; Kotaka, K.; Toriyama, M.

    1996-01-01

    From 1974 through 1992, 37 previously untreated patients with T3 laryngeal cancer (supraglottic 15, glottic 22) were treated with initial radical radiotherapy and surgery for salvage. Two-year local control rate with radiotherapy alone, ultimate voice preservation rate, and ultimate local control rate for T3 supraglottic cancer were 33%, 33%, and 60%, respectively. Corresponding figures for T3 glottic cancer were 32%, 23%, and 77%, respecitvely. Five-year cause-specific survival rate for T3 supraglottic cancer and glottic cancer were 47% and 77%, respectively. In T3 supraglottic cancer, none of the 4 patients with subglottic tumor extension attained local control by radiotherapy alone, and local-regional recurrence-free time were significantly shorter in patients with subglottic tumor extension or tracheostomy before radiotherapy. There were no serious late complications such as chondronecrosis, rupture of carotid artery attributed to radical radiotherapy, while 3 patients had severe laryngeal edema requiring total laryngectomy. (orig.) [de

  11. Editorial: RADICALISM AND POLITICS OF RELIGION

    Directory of Open Access Journals (Sweden)

    Editorial Al-Jami'ah: Journal of Islamic Studies

    2008-02-01

    Full Text Available Radical Islamism has become the “sexiest” issue in the international scholarship of religion since the September 11 tragedy in 2001. It has been associated with a number of terrorist attacks not only in the West but also in Muslim countries. Every single of radical Islamism has caught the interest of not only scholars and policy makers but also general public. Interestingly, the general assumption that religion is the source of peace has been seriously challenged, not by non-religious communities, but by the violent practices of particular religious groups, however small they are. Indeed, there are certain groups striving for Islam but by using acts which could give awful image on Islam itself and against humanity.

  12. Freedom Now! Radical Jazz and Social Movements

    Directory of Open Access Journals (Sweden)

    Przemysław Pluciński

    2014-01-01

    Full Text Available Music is obviously not only an aesthetic phenomenon. It is embeddedin a dense network of social relations. However, its social involvementis rather ambiguous, particularly since the second half of the twentiethcentury. On the one hand, music is one of the main elements of culturalcapitalism and a part of the system of domination. On the other hand,music provokes, (coproduces or possibly strengthens and coexists witha number of counterdiscourses and social projects of counterhegemoniccharacter.The main objective of the paper is to examine relationships between both, revolutionary jazz and revolutionary social movements, namely the civil rights movement, but above all radical movements, especially black power movement. The crucial questions I am interested in are problems of selforganization, performative social practices, as well as alternatives elaborated by radical-oriented jazz circles in various social dimensions, for instance economic or symbolic.

  13. Electronic spectrum of 9-methylanthracenium radical cation

    Energy Technology Data Exchange (ETDEWEB)

    O’Connor, Gerard D.; Schmidt, Timothy W., E-mail: timothy.schmidt@unsw.edu.au [School of Chemistry, UNSW Sydney, New South Wales 2052 (Australia); Sanelli, Julian A.; Dryza, Vik; Bieske, Evan J. [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia)

    2016-04-21

    The predissociation spectrum of the cold, argon-tagged, 9-methylanthracenium radical cation is reported from 8000 cm{sup −1} to 44 500 cm{sup −1}. The reported spectrum contains bands corresponding to at least eight electronic transitions ranging from the near infrared to the ultraviolet. These electronic transitions are assigned through comparison with ab initio energies and intensities. The infrared D{sub 1}←D{sub 0} transitions exhibit significant vibronic activity, which is assigned through comparison with TD-B3LYP excited state frequencies and intensities, as well as modelled vibronic interactions. Dissociation of 9-methylanthracenium is also observed at high visible-photon energies, resulting in the loss of either CH{sub 2} or CH{sub 3}. The relevance of these spectra, and the spectra of other polycyclic aromatic hydrocarbon radical cations, to the largely unassigned diffuse interstellar bands, is discussed.

  14. Peace journalism and radical media ethics

    Directory of Open Access Journals (Sweden)

    Marta Natalia Lukacovic

    2016-10-01

    Full Text Available The radical characteristics of peace journalism position it as a model that expands the current understandings of normative media theory. Peace journalism echoes the most innovative calls of media ethicists, such as the proposition of radical media ethics. This idea asserts the necessity to expand media ethics to better fit the globalized and democratized media landscape, which is enabled by contemporary new media technologies. Essentially a global shift, among professionals as well as regular citizen-communicators, should advance towards conflict sensitivity in order to transcend the culturally violent elements of covering conflicts. Similar efforts will bring numerous challenges, however, these efforts are tremendously worthwhile with their potential to assist the creation of more peace-prone global societies.

  15. Radical pancreatectomy: postoperative evaluation by CT

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, J.P.; Balfe, D.M.; Picus, D.; Scharp, D.W.

    1984-10-01

    Twenty-four patients who had undergone radical pancreatic resection were evaluated by CT one week to 11 years after surgery. Eighteen patients had had the Whipple procedure; six had had total pancreatectomy. The region between the aorta and superior mesenteric artery, previously occupied by the uncinate process of the pancreas, is an important area to evaluate for tumor recurrence because periampullary tumors tend to metastasize to the lymph nodes in this region. Tumor recurrence here is readily detectable by CT since radical pancreatectomy leaves this area area free of soft tissue attenuation material. CT demonstrated postoperative complications or tumor recurrence in 16 of the 24 patients and was 100% accurate in patients who had follow-up.

  16. International Radical Cystectomy Consortium: A way forward

    Directory of Open Access Journals (Sweden)

    Syed Johar Raza

    2014-01-01

    Full Text Available Robot-assisted radical cystectomy (RARC is an emerging operative alternative to open surgery for the management of invasive bladder cancer. Studies from single institutions provide limited data due to the small number of patients. In order to better understand the related outcomes, a world-wide consortium was established in 2006 of patients undergoing RARC, called the International Robotic Cystectomy Consortium (IRCC. Thus far, the IRCC has reported its findings on various areas of operative interest and continues to expand its capacity to include other operative modalities and transform it into the International Radical Cystectomy Consortium. This article summarizes the findings of the IRCC and highlights the future direction of the consortium.

  17. Coming to Grips with Radical Social Constructivisms

    Science.gov (United States)

    Phillips, D. C.

    This essay distinguishes two broad groups - psychological constructivists and social constructivists - but focusses upon the second of these, although it is stressed that there is great within group variation. More than half of the paper is devoted to general clearing of the ground, during which the reasons for the growing acrimony in the debates between social constructivists and their opponents are assessed, an important consequence of these debates for education is discussed, and an examination is carried out of the radical social constructivist tendency to make strong and exciting but untenable claims which are then backed away from (a tendency which is documented by a close reading of the early pages in Bloors classic book). The last portion of the essay focuses upon social constructivist accounts of the causes of belief in science - the more radical of which denegrate the role of warranting reasons, and which give an exalted place to quasi-anthropological or sociological studies of scientific communities.

  18. Radical pancreatectomy: postoperative evaluation by CT

    International Nuclear Information System (INIS)

    Heiken, J.P.; Balfe, D.M.; Picus, D.; Scharp, D.W.

    1984-01-01

    Twenty-four patients who had undergone radical pancreatic resection were evaluated by CT one week to 11 years after surgery. Eighteen patients had had the Whipple procedure; six had had total pancreatectomy. The region between the aorta and superior mesenteric artery, previously occupied by the uncinate process of the pancreas, is an important area to evaluate for tumor recurrence because periampullary tumors tend to metastasize to the lymph nodes in this region. Tumor recurrence here is readily detectable by CT since radical pancreatectomy leaves this area area free of soft tissue attenuation material. CT demonstrated postoperative complications or tumor recurrence in 16 of the 24 patients and was 100% accurate in patients who had follow-up

  19. EPR study of free radicals in bread

    Science.gov (United States)

    Yordanov, Nicola D.; Mladenova, Ralitsa

    2004-05-01

    The features of the recorded EPR spectra of paramagnetic species formed in bread and rusk are reported. The appearance of free radicals in them is only connected with their thermal treatment since the starting materials (flour and grains) exhibit very weak EPR signal. The obtained EPR spectra are complex and indicate that: (i) the relative number of paramagnetic species depends on the temperature and treating time of the raw product; (ii) the g-values are strongly temperature dependent with a tendency to coincide at t≥220 °C. Because of the relatively low (150-220 °C) temperature of thermal treatment, the studied free radicals can be assumed to appear in the course of the browning (Maillard) reaction and not to the carbonization of the material.

  20. EARLY POSTOPERATIVE COMPLICATIONS AFTER RADICAL CYSTECTOMY

    Directory of Open Access Journals (Sweden)

    V. O. Mager

    2014-08-01

    Full Text Available Radical cystectomy (RCE is associated with a considerable number of early postoperative complications as before. Based on 10 years’ experience, this paper demonstrates the frequency (33.9 % and types of early complications following RCE, as well as postoperative mortality (5.5 % and its resulting causes. Although postoperative mortality is relatively low today, the frequency of early postoperative complications remains high as before.

  1. Hydroxyl free radical production during torsional phacoemulsification.

    Science.gov (United States)

    Aust, Steven D; Hebdon, Thomas; Humbert, Jordan; Dimalanta, Ramon

    2010-12-01

    To quantitate free radical generation during phacoemulsification using an ultrasonic phacoemulsification device that includes a torsional mode and evaluate tip designs specific to the torsional mode. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. Experimental study. Experiments were performed using the Infiniti Vision System and OZil handpiece. Hydroxyl radical concentrations in the aspirated irrigation solution during torsional phacoemulsification were quantitated as nanomolar malondialdehyde (nM MDA) and determined spectrophotometrically using the deoxyribose assay. The mean free radical production during phacoemulsification with torsional modality at 100% amplitude was 30.1 nM MDA ± 5.1 (SD) using a 0.9 mm 45-degree Kelman tapered ABS tip. With other tip designs intended for use with the torsional modality, free radical production was further reduced when fitted with the 0.9 mm 45-degree Kelman mini-flared ABS tip (13.2 ± 5.6 nM MDA) or the 0.9 mm 45-degree OZil-12 mini-flared ABS tip (14.3 ± 6.7 nM MDA). Although the measurements resulting from the use of the latter 2 tips were not statistically significantly different (P ≈ .25), they were different from those of the tapered tip (P<.0001). The MDA concentration in the aspirated irrigation solution using the torsional modality was approximately one half that reported for the handpiece's longitudinal modality in a previous study using the same bent-tip design (Kelman tapered, P<.0001). The level of MDA was further reduced approximately one half with torsional-specific tips. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  2. How Hume's Philosophy Informed Radical Behaviorism.

    Science.gov (United States)

    Nuzzolilli, Andrew E; Diller, James W

    2015-05-01

    The present paper analyzes consistencies between the philosophical systems of David Hume and B. F. Skinner, focusing on their conceptualization of causality and attitudes about scientific behavior. The ideas that Hume initially advanced were further developed in Skinner's writings and shaped the behavior-analytic approach to scientific behavior. Tracing Skinner's logical antecedents allows for additional historical and philosophical clarity when examining the development of radical behaviorism.

  3. Western Radicalization: Rethinking the Psychology of Terrorism

    Science.gov (United States)

    2017-03-01

    to do so, they assert, locks both the researcher and the research subject into a “spiral of ignorance and suspicion.” Moreover, “social identity ...percentage of firefighters who commit this type of arson do so to establish an identity and sense of belonging. Similarly, disconnected Westerners...percentage of firefighters who commit this type of arson do so to establish an identity and sense of belonging. Similarly, disconnected Westerners radicalize

  4. Computed tomography after radical pancreaticoduodenectomy (Whipple's procedure)

    International Nuclear Information System (INIS)

    Smith, S.L.; Hampson, F.; Duxbury, M.; Rae, D.M.; Sinclair, M.T.

    2008-01-01

    Whipple's procedure (radical pancreaticoduodenectomy) is currently the only curative option for patients with periampullary malignancy. The surgery is highly complex and involves multiple anastomoses. Complications are common and can lead to significant postoperative morbidity. Early detection and treatment of complications is vital, and high-quality multidetector computed tomography (MDCT) is currently the best method of investigation. This review outlines the surgical technique and illustrates the range of normal postoperative appearances together with the common complications

  5. Radicalization as a Vector: Exploring Non-Violent and Benevolent Processes of Radicalization.

    Directory of Open Access Journals (Sweden)

    Ken Reidy

    2018-03-01

    Full Text Available Successful radicalization posits three outcomes: extremism, terrorism or both. As these are undesirable, radicalization is understood as wholly malevolent and governments work to prevent and/or stop it. Nonetheless, a handful of scholars have recognized that the same radicalization process which results in either outcome may, theoretically at least, also have beneficial outcomes such as environmental awareness or human rights. This article explores one such outcome. Based on interviews with British Muslim aid workers (n=6 operating in Jihadist conflict zones post Arab spring and using constructivist grounded theory, it illustrates how the research participants radicalized to humanitarianism which resulted in them assisting the most plighted of Muslims by deploying to the most wanton of areas: ones commonly referred to as Jihadist conflict zones. Evidently, these destinations are shared with Jihadists and given the array of other observable similarities (socio-demographics and [pre-]mobilization behaviours, these morally opposed groups become conflated by the security services. This is further compounded by the fact that Jihadists manipulate and/or impersonate aid workers so as to funnel people and funds. To distinguish both, this article documents the benevolent pathway of the research participants and juxtaposes it to scholarly knowledge on Jihadist pathways. Socialization was revealed to be the key distinguishing feature rather than descriptive risk factors (such as ideology or moral outrage because the process of radicalization was not found to be the start of the radicalized pathway. It concludes that benevolently radicalized Islamic groups constitute an effective means of pathway divergence for particular typologies by offering an attractive and prosocial alternative to Jihadism. This strengths-based preventative approach (“what’s right” takes the form of a community-centric market competitor to Jihadism rather than a problem

  6. Free radicals induced archive paper by irradiation

    International Nuclear Information System (INIS)

    Cutrubinis, M.; Moise, I.V.; Negut, C.D.; Georgescu, R.; Suvaila, R.; Virgolici, M.; Manea, M.M.

    2011-01-01

    Complete text of publication follows. Irradiation of archive paper (document archives of institutions, companies etc. and library or museum collections of books and documents) can solve the problems related to the bio-deterioration and bio-contamination of paper and sometimes save valuable cultural heritage paper items. For valuable paper items care should be taken to the degradation induced instantly by the ionising radiation to the cellulosic support and also to the long term post-irradiation effects. The free radicals formed due to the irradiation treatment could contribute to instant degradation of paper. Part of them are also trapped for months and years after irradiation and they could be related to the post-irradiation effects in paper items. In this study, different sorts of cellulosic support samples (soft wood and hard wood cellulose, contemporary paper, paper from archives and from collections etc.) have been irradiated with dosis up to 100 kGy and the radiation induced free radicals have been measured by ESR spectrometry. The ESR signals have shown the type and quantity of radiation induced free radicals. Their study can be used for a realistic estimation of the degradative effect of the ionising radiation treatment of archive paper.

  7. Complications of Radical Cystectomy and Orthotopic Reconstruction

    Directory of Open Access Journals (Sweden)

    Wei Shen Tan

    2015-01-01

    Full Text Available Radical cystectomy and orthotopic reconstruction significant morbidity and mortality despite advances in minimal invasive and robotic technology. In this review, we will discuss early and late complications, as well as describe efforts to minimize morbidity and mortality, with a focus on ileal orthotopic bladder substitute (OBS. We summarise efforts to minimize morbidity and mortality including enhanced recovery as well as early and late complications seen after radical cystectomy and OBS. Centralisation of complex cancer services in the UK has led to a fall in mortality and high volume institutions have a significantly lower rate of 30-day mortality compared to low volume institutions. Enhanced recovery pathways have resulted in shorter length of hospital stay and potentially a reduction in morbidity. Early complications of radical cystectomy occur as a direct result of the surgery itself while late complications, which can occur even after 10 years after surgery, are due to urinary diversion. OBS represents the ideal urinary diversion for patients without contraindications. However, all patients with OBS should have regular long term follow-up for oncological surveillance and to identify complications should they arise.

  8. Radical Homemaking in Contemporary American Environmental Fiction

    Directory of Open Access Journals (Sweden)

    Kristin J. Jacobson

    2018-02-01

    Full Text Available Ursula K. Heise in ‘Ecocriticism and the Transnational Turn in American Studies’ critiques ‘the portrayal of multicultural and sometimes transnational nuclear families as the narrative solution to environmental and political problems’ (Heise, 2008: 383. This essay places Heise’s critique of the ‘ecological family romance’ in conversation with three other ecological domestic fictions: T. C. Boyle’s 'A Friend of the Earth' (2000, Jonathan Franzen’s 'Freedom' (2010, and Barbara Kingsolver’s 'Flight Behavior' (2012. Heise’s critique and Shannon Hayes’ 'Radical Homemakers' (2010 frame my close readings of the novels’ interconnected themes of radical homemaking, transnationalism, and environmentalism. My reading of the novels highlights their shared use of marginalized, racially-other characters to develop their entwined romantic and environmental plots (Lalitha in 'Freedom', several minor characters in 'A Friend of the Earth', and Ovid in 'Flight Behavior' and their use of sentimental deaths, especially of key female characters (Lalitha in Freedom, Sierra in A Friend of the Earth, and Dellarobia’s uncertain fate in Flight Behavior. By adopting the sentimental, domestic romance plot for ecological aims, the three novels highlight how environmental aims get stymied when cultural and ecological diversity are relegated to the margins. They also suggest that more is gained than lost through their use of ecological allegory. While the fictions do not offer solutions, they do push their readers to confront the Anthropocene’s ecological realities and their radical domestic-environmental politics.

  9. The Rise of Radicals in Bioinorganic Chemistry.

    Science.gov (United States)

    Gray, Harry B; Winkler, Jay R

    2016-10-01

    Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O 2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O 2 -reactive enzymes, raising the possibility that they play an antioxidant protective role. In blue copper proteins with plastocyanin-like domains, Tyr/Trp clusters are uncommon in the low-potential single-domain electron-transfer proteins and in the two-domain copper nitrite reductases. The two-domain muticopper oxidases, however, exhibit clusters of Tyr and Trp residues near the trinuclear copper active site where O 2 is reduced. These clusters may play a protective role to ensure that reactive oxygen species are not liberated during O 2 reduction.

  10. Peroxy Radical Measurements via Laser Induced Fluorescence

    Science.gov (United States)

    Trawny, Katrin; Tatum Ernest, Cheryl; Novelli, Anna; Elste, Thomas; Plaß-Dülmer, Christian; Rudolf, Markus; Martinez, Monica; Harder, Hartwig; Lelieveld, Jos

    2013-04-01

    We present a newly built Laser Induced Fluorescence (LIF) system to measure the sum of all peroxy radicals (RO2) utilizing chemical conversion to OH. This instrument operates in two different modes: the ROx mode (sum of OH, HO2, and RO2) and the HOx mode (sum of OH and HO2). The HOx mode is used to derive the RO2 data from the ROx measurements. A model approach was used during instrumental development to identify the key parameters needed for the conversion process in front of the detection area and to optimize sensitivity. The instrument was then carefully characterized in various lab experiments, where it could be shown that the wall losses for HO2 are negligible and that nearly all HO2 is converted to OH in front of the detection zone. The pressure and temperature dependencies were also analyzed and assured that the instrument does not show any photolytical interference. As the instrument is calibrated with only one kind of peroxy radicals it was very important that the differences in sensitivity for different peroxy radicals are acceptable. Lab experiments as well as first results from the HOPE 2012 intensive field campaign, which took place in summer 2012 at the Global Atmosphere Watch (GAW) station of the German Weather Service, will be discussed.

  11. Laparoscopic radical prostatectomy in the canine model.

    Science.gov (United States)

    Price, D T; Chari, R S; Neighbors, J D; Eubanks, S; Schuessler, W W; Preminger, G M

    1996-12-01

    The purpose of this study was to determine the feasibility of performing laparoscopic radical prostatectomy in a canine model. Laparoscopic radical prostatectomy was performed on six adult male canines. A new endoscopic needle driver was used to construct a secure vesicourethral anastomosis. Average operative time required to complete the procedure was 304 min (range 270-345 min). Dissection of the prostate gland took an average of 67 min (range 35-90 min), and construction of the vesicourethral anastomosis took 154 min (rage 80-240 min). There were no intraoperative complications and only one postoperative complication (anastomotic leak). Five of the six animals recovered uneventfully from the procedure, and their foley catheters were removed 10-14 days postoperatively after a retrograde cystourethrogram demonstrated an intact vesicourethral anastomosis. Four (80%) of the surviving animals were clinically continent within 10 days after catheter removal. Post mortem examination confirmed that the vesicourethral anastomosis was intact with no evidence of urine extravasation. These data demonstrate the feasibility of laparoscopic radical prostatectomy in a canine model, and suggest that additional work with this technique should be continued to develop its potential clinical application.

  12. Radical inactivation of a biological sulphydryl molecule

    International Nuclear Information System (INIS)

    Lin, W.S.; Lal, M.; Gaucher, G.M.; Armstrong, D.A.

    1977-01-01

    Reactive species produced from the free radical-induced chain oxidation of low molecular weight sulphydryl-containing molecules in aerated solutions deactivate the sulphydryl-containing enzyme papain, forming both reparable mixed disulphides and non-reparable products. This inactivation is highly efficient for penicillamine and glutathione, but almost negligible with cysteine, which is a protector of papain for [cysteine] / [papain] >= 5 under all conditions used. In the case of glutathione, superoxide dismutase caused only a small reduction in the inactivation and peroxide yields were small, implying that the deactivating species are not .O 2 - but RSOO. radicals or products from them. For penicillamine, however, dimutase was highly effective and the peroxide yields were relatively large, demonstrating that .O 2 - or a radical with similar capabilities for forming H 2 O 2 and being deactivated by dismutase was involved. Although in the presence of dismutase penicillamine is a better protector of non-reparable papain inactivation than glutathione, it suffers from a deficiency in that the papain-penicillamine mixed disulphide, which is always formed, cannot be repaired by spontaneous reaction with RSH molecules. (author)

  13. Orthographic Skills Important to Chinese Literacy Development: The Role of Radical Representation and Orthographic Memory of Radicals

    Science.gov (United States)

    Yeung, Pui-sze; Ho, Connie Suk-han; Chan, David Wai-ock; Chung, Kevin Kien-hoa

    2016-01-01

    A 3-year longitudinal study among 239 Chinese students in Grades 2-4 was conducted to investigate the relationships between orthographic skills (including positional and functional knowledge of semantic radicals and phonetic radicals, and orthographic memory of radicals) and Chinese literacy skills (word reading, word spelling, reading…

  14. Generation and propagation of radical reactions on proteins

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    2001-01-01

    The oxidation of proteins by free radicals is thought to play a major role in many oxidative processes within cells and is implicated in a number of human diseases as well as ageing. This review summarises information on the formation of radicals on peptides and proteins and how radical damage may...... be propagated and transferred within protein structures. The emphasis of this article is primarily on the deleterious actions of radicals generated on proteins, and their mechanisms of action, rather than on enzymatic systems where radicals are deliberately formed as transient intermediates. The final section...

  15. Formation and spectroscopy of {alpha}-muoniated radicals

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, I.; Brodovitch, J.C.; Ghandi, K.; Kecman, S.; Percival, P.W

    2003-02-01

    Several novel {alpha}-muoniated radicals have been produced by the reaction of muonium with compounds containing diazo, isocyanate or carbene functional groups. In {alpha}-muoniated radicals the muon is attached directly to the radical centre; they can be formed either directly or indirectly via a {beta}-muoniated radical intermediate. The hyperfine coupling constants of the resulting radicals have been measured by transverse field muon spin rotation and muon avoided level-crossing resonance. The effect of muonium substitution was investigated for cases where ESR data are available for comparison.

  16. Formation and spectroscopy of α-muoniated radicals

    International Nuclear Information System (INIS)

    McKenzie, I.; Brodovitch, J.C.; Ghandi, K.; Kecman, S.; Percival, P.W.

    2003-01-01

    Several novel α-muoniated radicals have been produced by the reaction of muonium with compounds containing diazo, isocyanate or carbene functional groups. In α-muoniated radicals the muon is attached directly to the radical centre; they can be formed either directly or indirectly via a β-muoniated radical intermediate. The hyperfine coupling constants of the resulting radicals have been measured by transverse field muon spin rotation and muon avoided level-crossing resonance. The effect of muonium substitution was investigated for cases where ESR data are available for comparison

  17. Reactions of melatonin with radicals in deoxygenated aqueous solution

    International Nuclear Information System (INIS)

    Stasica, P.; Ulanski, P.; Rosiak, J.M.

    1998-01-01

    Reactions of melatonin (N-acetyl-5-methoxytryptamine) with radiolytically generated radicals were studied. Reaction of melatonin with OH radicals is diffusion-controlled (k=1.2 x 10 10 dm 3 mol -1 x s -1 ), the main (but not the only one) intermediate being the indolyl-type radical, while the rate constant for the reaction with hydrated electrons is k=4.3 x 10 8 dm 3 x mol -1 x s -1 . Melatonin is capable of scavenging tert-butanol radicals, while its reactivity towards polymer radicals of poly(acrylic acid) and poly(vinyl pyrrolidone) is very low. (author)

  18. Dynamic mechanistic modeling of the multienzymatic one-pot reduction of dehydrocholic acid to 12-keto ursodeoxycholic acid with competing substrates and cofactors.

    Science.gov (United States)

    Sun, Boqiao; Hartl, Florian; Castiglione, Kathrin; Weuster-Botz, Dirk

    2015-01-01

    Ursodeoxycholic acid (UDCA) is a bile acid which is used as pharmaceutical for the treatment of several diseases, such as cholesterol gallstones, primary sclerosing cholangitis or primary biliary cirrhosis. A potential chemoenzymatic synthesis route of UDCA comprises the two-step reduction of dehydrocholic acid to 12-keto-ursodeoxycholic acid (12-keto-UDCA), which can be conducted in a multienzymatic one-pot process using 3α-hydroxysteroid dehydrogenase (3α-HSDH), 7β-hydroxysteroid dehydrogenase (7β-HSDH), and glucose dehydrogenase (GDH) with glucose as cosubstrate for the regeneration of cofactor. Here, we present a dynamic mechanistic model of this one-pot reduction which involves three enzymes, four different bile acids, and two different cofactors, each with different oxidation states. In addition, every enzyme faces two competing substrates, whereas each bile acid and cofactor is formed or converted by two different enzymes. First, the kinetic mechanisms of both HSDH were identified to follow an ordered bi-bi mechanism with EBQ-type uncompetitive substrate inhibition. Rate equations were then derived for this mechanism and for mechanisms describing competing substrates. After the estimation of the model parameters of each enzyme independently by progress curve analyses, the full process model of a simple batch-process was established by coupling rate equations and mass balances. Validation experiments of the one-pot multienzymatic batch process revealed high prediction accuracy of the process model and a model analysis offered important insight to the identification of optimum reaction conditions. © 2015 American Institute of Chemical Engineers.

  19. What is Radical Behaviorism? A Review of Jay Moore's Conceptual Foundations of Radical Behaviorism

    Science.gov (United States)

    Baum, William M

    2011-01-01

    B. F. Skinner founded both radical behaviorism and behavior analysis. His founding innovations included: a versatile preparation for studying behavior; explicating the generic nature of stimulus and response; a pragmatic criterion for defining behavioral units; response rate as a datum; the concept of stimulus control; the concept of verbal behavior; and explicating the explanatory power of contingencies. Besides these achievements, however, Skinner also made some mistakes. Subsequent developments in radical behaviorist thought have attempted to remedy these mistakes. Moore's book presents a “party line” version of radical behaviorism. It focuses narrowly on a few of Skinner's concepts (mostly mentalism and verbal behavior) and contains no criticism of his mistakes. In fact, Moore adds a few mistakes of his own manufacture; for example, he insists that the mental realm does not exist—an unprovable and distracting assertion. The book's portrayal of behavior analysis would have been current around 1960; it mentions almost none of the developments since then. It also includes almost no developments in radical behaviorism since Skinner. Moore's book would give an unwary reader a highly distorted picture of contemporary behavior analysis and radical behaviorism.

  20. Total free radical species and oxidation equivalent in polluted air.

    Science.gov (United States)

    Wang, Guoying; Jia, Shiming; Niu, Xiuli; Tian, Haoqi; Liu, Yanrong; Chen, Xuefu; Li, Lan; Zhang, Yuanhang; Shi, Gaofeng

    2017-12-31

    Free radicals are the most important chemical intermediate or agent of the atmosphere and influenced by thousands of reactants. The free radicals determine the oxidizing power of the polluted air. Various gases present in smog or haze are oxidants and induce organ and cellular damage via generation of free radical species. At present, however, the high variability of total free radicals in polluted air has prevented the detection of possible trends or distributions in the concentration of those species. The total free radicals are a kind of contaminants with colorless, tasteless characteristics, and almost imperceptible by human body. Here we present total free radical detection and distribution characteristics, and analyze the effects of total free radicals in polluted air on human health. We find that the total free radical values can be described by not only a linear dependence on ozone at higher temperature period, but also a linear delay dependence on particulate matter at lower temperature period throughout the measurement period. The total free radical species distribution is decrease from west to east in Lanzhou, which closely related to the distribution of the air pollutants. The total free radical oxidation capacity in polluted air roughly matches the effects of tobacco smoke produced by the incomplete combustion of a controlled amount of tobacco in a smoke chamber. A relatively unsophisticated chromatographic fingerprint similarity is used for indicating preliminarily the effect of total free radicals in polluted air on human health. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Electron spin resonance study of radicals in irradiated polyethylene

    International Nuclear Information System (INIS)

    Fujimura, Takashi

    1979-02-01

    In order to elucidate radiation effect in polyethylene, the nature and behavior of radicals produced in polyethylene and the model compound of polyethylene irradiated at 77 0 K were studied by using electron spin resonance. The structure of radical pairs, which are composed of two radicals produced very closely each other, was investigated in drawn polyethylene and the single crystal of n-eicosane. The radical pairs of intrachain type and interchain type were found in polyethylene and n-eicosane respectively. It was suggested that these two types of radical pairs are the precursors of double bonds and crosslinks respectively. The thermal decay reactions of radicals themselves produced in irradiated polyethylene were investigated. It was made clear that the short range distances between two radicals play an important role in the decay reaction of alkyl radicals at low temperatures. The trapping regions of radicals were studied and it was clarified that allyl radicals, which are produced by the reaction of alkyl radicals with double bonds, are trapped both in the crystalline and non-crystalline regions. (author)

  2. OH radical induced depolymerization of poly(methacrylic acid)

    Science.gov (United States)

    Ulanski, Piotr; Bothe, Eberhard; von Sonntag, Clemens

    1999-05-01

    Hydroxyl radicals (generated pulse radiolytically in dilute N 2O-saturated aqueous solutions) react with poly(methacrylic acid) producing two kinds of radicals. The primary radical is converted into a secondary one by H-abstraction ( k=3.5 × 10 2 s -1) as monitored by changes in the UV spectrum. Subsequently, the secondary radicals undergo chain scission ( k=1.8 s -1 at pH 7-9). This process has been followed both by spectrophotometry as well as by conductometry. In competition with the bimolecular decay of the radicals the ensuing end-chain radicals undergo efficient depolymerization resulting in the release of monomer. Since the lifetime of the radicals is much longer at high pH, where the polymer attains a rod-like conformation, depolymerization is most efficient in basic solution.

  3. Reactions of carbonate radical with cobalt(II) aminopolycarboxylates

    International Nuclear Information System (INIS)

    Mandal, P.C.; Bardhan, D.K.; Bhattacharyya, S.N.

    1992-01-01

    Reactions of carbonate (CO 3 - radical) and bicarbonate (HCO 3 radical) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 10 6 -10 7 dm 3 mol -1 s -1 . From the time-resolved spectroscopy of the products formed after reaction of CO 3 - radical or HCO 3 radical, it is observed that CO 3 - radical or HCO 3 radical oxidize the metal center to its higher oxidation state. (author) 26 refs.; 2 figs.; 1 tab

  4. Pharmacoepidemiological assessment of adherence and influencing co-factors among primary open-angle glaucoma patients-An observational cohort study.

    Directory of Open Access Journals (Sweden)

    Stefanie Frech

    Full Text Available The goal of this study was to assess the adherence of primary open-angle glaucoma (POAG patients to medication, and to determine co-factors influencing adherence, using a representative sample of members of the largest German public health insurer. The observational cohort study was based on a longitudinal data set from 2010-2013 and included 250,000 insured persons aged 50 and older with 10,120 diagnosed POAG patients. Uni- and multivariate analysis was performed to investigate several aspects of glaucoma, such as prevalence, adherence, and co-factors influencing adherence. The main outcome measured adherence with prescriptions filled within a year. Multivariate panel regression analysis was used to determine the co-factors influencing this adherence. Prevalence of POAG was 3.36% [CI: 3.28-3.43%], with 2.91% [CI: 2.81-3.01%] for males and 3.71% [CI: 3.61-3.81%] for females, increasing with age. The mean level of adherence in terms of prescriptions filled was 66.5% [CI: 65.50-67.60%]. The results of this analysis revealed a significant influence of age, duration of the disease, care need, distance to death, and multimorbidity as co-factors of non-adherence, whereas gender had no influence. The analysis provided detailed information about POAG health care aspects concerning prevalence and adherence. The most endangered risk groups for non-adherence were patients aged 50-59, patients older than 80 years, patients with a longer duration of POAG, patients with care needs, and patients with three or more severe diseases in addition to glaucoma. To know the predictors responsible for an increased risk to develop POAG is of importance for all persons involved in health care management. Therefore effective strategies to increase awareness of patients and medical care personnel about non-adherence and the importance of a regular and continuous medication to avoid further nerve fiber damage and possible blindness have to be developed.

  5. Synthesis and characterization of sulfur-voided cubanes. Structural analogues for the MoFe(3)S(3) subunit in the nitrogenase cofactor.

    Science.gov (United States)

    Coucouvanis, Dimitri; Han, Jaehong; Moon, Namdoo

    2002-01-16

    A new class of Mo/Fe/S clusters with the MoFe(3)S(3) core has been synthesized in attempts to model the FeMo-cofactor in nitrogenase. These clusters are obtained in reactions of the (Cl(4)-cat)(2)Mo(2)Fe(6)S(8)(PR(3))(6) [R = Et (I), (n)Pr (II)] clusters with CO. The new clusters include those preliminarily reported: (Cl(4)-cat)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (III), (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(3)(CO)(5) (IV), (Cl(4)-cat)(Pyr)MoFe(3)S(3)(PEt(3))(2)(CO)(6) (VI), and (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(4) (VIII). In addition the new (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(3)(CO)(5) cluster (IVa), the (Cl(4)-cat)(O)MoFe(3)S(3)(PEt(3))(2)(CO)(6)cluster (V), the (Cl(4)-cat)(O)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (Va), the (Cl(4)-cat)(Pyr)MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VIa), and the (Cl(4)-cat)(P(n)Pr(3))MoFe(3)S(3)(P(n)Pr(3))(2)(CO)(6) cluster (VII) also are reported. Clusters III-VIII have been structurally and spectroscopically characterized. EPR, zero-field (57)Fe-Mössbauer spectroscopic characterizations, and magnetic susceptibility measurements have been used for a tentative assignment of the electronic and oxidation states of the MoFe(3)S(3) sulfur-voided cuboidal clusters. A structural comparison of the clusters with the MoFe(3)S(3) subunit of the FeMo-cofactor has led to the suggestion that the storage of reducing equivalents into M-M bonds, and their use in the reduction of substrates, may occur with the FeMo-cofactor, which also appears to have M-M bonding. On the basis of this argument, a possible N(2)-binding and reduction mechanism on the FeMoco-cofactor is proposed.

  6. Radical intermediates involved in the bleaching of the carotenoid crocin. Hydroxyl radicals, superoxide anions and hydrated electrons

    International Nuclear Information System (INIS)

    Bors, W.; Saran, M.; Michel, C.

    1982-01-01

    The participation of the primary radicals in the bleaching of aqueous solutions of the carotenoid crocin by ionizing radiation was investigated, employing both X-radiolysis and pulse radiolysis. The pulse-radiolytic data demonstrated a very rapid diffusion-controlled attack by both hydroxyl radicals (radicalsOH) and hydrated electrons (e - sub(aq)), while superoxide anions (O 2 - ) did not react at all. The site of the initial reaction of these radicals was not limited to the polyene chromophore. Slower secondary reactions involving crocin alkyl or peroxy radicals contribute mainly to the overall bleaching, in particular during steady-state irradiation. (author)

  7. Even free radicals should follow some rules: a guide to free radical research terminology and methodology.

    Science.gov (United States)

    Forman, Henry Jay; Augusto, Ohara; Brigelius-Flohe, Regina; Dennery, Phyllis A; Kalyanaraman, Balaraman; Ischiropoulos, Harry; Mann, Giovanni E; Radi, Rafael; Roberts, L Jackson; Vina, Jose; Davies, Kelvin J A

    2015-01-01

    Free radicals and oxidants are now implicated in physiological responses and in several diseases. Given the wide range of expertise of free radical researchers, application of the greater understanding of chemistry has not been uniformly applied to biological studies. We suggest that some widely used methodologies and terminologies hamper progress and need to be addressed. We make the case for abandonment and judicious use of several methods and terms and suggest practical and viable alternatives. These changes are suggested in four areas: use of fluorescent dyes to identify and quantify reactive species, methods for measurement of lipid peroxidation in complex biological systems, claims of antioxidants as radical scavengers, and use of the terms for reactive species. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. O Behaviorismo Radical como filosofia da mente Radical Behaviorism as philosophy of mind

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Lopes

    2003-01-01

    Full Text Available O Behaviorismo Radical de B. F. Skinner é constantemente acusado de eliminar a mente de sua explicação do comportamento humano. Uma análise do livro The Concept of Mind, de Gilbert Ryle, sugere a possibilidade de defender a existência de uma mente relacional, diferente da categoria de existência da mente defendida em interpretações cartesianas (mente substancial. A análise de alguns textos de Skinner sugere que o conceito de uma mente relacional também pode ser defendido no Behaviorismo Radical. Esse fato, culminaria na possibilidade de que, além de filosofia da Ciência do Comportamento, o Behaviorismo Radical, também pode ser uma filosofia da mente, o que traria conseqüências ao estudo e à aplicação da Análise do Comportamento.B. F. Skinner's Radical Behaviorism has been repeatedly accused of eliminating the mind from its explanation of human behavior. An analysis of Gilbert Ryle's book, The Concept of Mind, suggests the possibility of defending the existence of a relational mind, different from the category of existence of mind defended in Cartesian interpretations (substantial mind. The analysis of some texts of Skinner suggests that the concept of a relational mind can also be defended in Radical Behaviorism. This fact would lead to the possibility that, beyond a philosophy of Behavior Science, Radical Behaviorism may also be a philosophy of mind, which would bring consequences to the study and application of Analysis of Behavior.

  9. Preoperative radiochemotherapy and radical surgery in comparison with radical surgery alone

    International Nuclear Information System (INIS)

    Mohr, C.; Schettler, D.; Bohndorf, W.

    1994-01-01

    A multicentric, randomized study of squamous cell carcinoma (SCC) of the oral cavity and the oropharynx has been undertaken by DOeSAK. The results after radical surgery alone have been compared with the results of combined preoperative radiochemotherapy followed by radical surgery. Patients with primary (biopsy proven) SCC of the oral cavity or the oropharynx with tumor nodes metastasis (TNM) stages T2-4, N0-3, M0 were included in the study. A total of 141 patients were treated by radical surgery alone, whereas 127 patients were treated by radical surgery preceded by preoperative radiochemotherapy. The pre-operative treatment consisted of conventionally fractioned irradiation on the primary and the regional lymph nodes with a total dose of 36 Gy (5 x 2 Gy per week) and low-dose cisplatin chemotherapy with 5 x 12.5 mg cisplatin per m 2 of body surface during the first week of treatment. Radical surgery according to be DOeSAK definitions (DOeSAK, 1982) was performed after a delay of 10-14 days. During the follow-up period, 28.2% of all patients suffered from locoregional recurrence, and 27.2% of the patients died. The percentages were higher after radical surgery alone for locoregional recurrence (31% and 15.6%) and for death (28% and 18.6%). The life-table analysis showed improved survival rates of 4.5% after 1 year and 8.3% after 2 years in the group of patients treated with combined therapy. The demonstrated improvement appeared to be significant with the Gehan-Wilcoxon test as well as with the log rank test below a P value of 5%. (au) (29 refs.)

  10. Effect of adding cofactors to exogenous fibrolytic enzymes on preingestive hydrolysis, in vitro digestibility, and fermentation of bermudagrass haylage.

    Science.gov (United States)

    Romero, J J; Ma, Z X; Gonzalez, C F; Adesogan, A T

    2015-07-01

    Our objectives were to examine if adding metal ion cofactors (COF) to exogenous fibrolytic enzymes (EFE) would increase the beneficial effects of the EFE on the preingestive hydrolysis and in vitro digestibility and fermentation of bermudagrass haylage. In experiment 1, 5 COF (Mn(2+), Co(2+), Fe(2+), Ca(2+), and Mg(2+)) were screened to select the best candidates for synergistically enhancing release of water-soluble carbohydrates (WSC) from bermudagrass haylage by 5 EFE. The 5 EFE (1A, 2A, 11C, 13D, and 15D) were sourced from Trichoderma reesei and Aspergillus oryzae and they were the most effective of 12 EFE at increasing the neutral detergent fiber digestibility of bermudagrass haylage in a previous trial. Adding 1mM of each of the COF to EFE 2A or 11C synergistically increased release of WSC from bermudagrass haylage, as did adding (1mM) Fe(2+) to 1A, Mn(2+), Co(2+), or Fe(2+) to 13D, or Co(2+)or Fe(2+) to 15D. The greatest release of WSC responses were obtained by adding Mn(2+) to 11C (38%) or by adding Fe(2+) to 2A or 13D (10 and 21.9%, respectively). In experiment 2, the effect of increasing the COF dose on in vitro digestibility and fermentation of bermudagrass haylage was examined using the best EFE-COF combinations from experiment 1. Effects of adding increasing doses of these COF on EFE-mediated changes in vitro digestibility depended on the COF-EFE combination. Adding 10mM Mn(2+) alone to bermudagrass haylage increased DMD and NDFD by 2.7 and 6.3% and adding 11C alone increased these measures by 6.6 and 15.5%, respectively. However, adding 10mM Mn(2+) with 11C resulted in 3.5 and 8.1% increases in DMD and NDFD, respectively, beyond the increases caused by adding 11C alone. Adding Fe(2+) to 2A had no effects on EFE-mediated digestibility responses, but 2A prevented adverse effects of adding Fe(2+) alone on DMD and NDFD. In contrast, adding Fe(2+) to 13D reduced the increases in DMD and NDFD caused by adding the EFE alone. This study shows that adding COF

  11. Leghemoglobin-derived radicals. Evidence for multiple protein-derived radicals and the initiation of peribacteroid membrane damage

    DEFF Research Database (Denmark)

    Moreau, S; Davies, Michael Jonathan; Mathieu, C

    1996-01-01

    , with the consequent generation of lipid-derived radicals. The formation of such radicals may result in the depletion of membrane antioxidants and the initiation of lipid peroxidation. This transfer of damage from the heme center via the protein surface to neighboring membranes may be of considerable biological......-derived phenoxyl radical present at Tyr-133 in the soybean protein and Tyr-138 in the lupin protein. To obtain further information on these protein radicals and their potential interaction with the physiologically important peribacteroid membrane (which surrounds the microsymbiont in vivo), EPR spin trapping......); these radicals may be side chain- or alpha-carbon-derived, their exact sites have not been determined. Some of these radicals are on the protein surface and may be key intermediates in the formation of protein dimers. These radicals have been shown to be capable of reacting with peribacteroid membrane fractions...

  12. Taking a radical position: Evidence for position specific radical representations in Chinese character recognition using masked priming ERP

    Directory of Open Access Journals (Sweden)

    I-Fan eSu

    2012-09-01

    Full Text Available In the investigation of orthographic representation of Chinese characters, one question that has stimulated much research is whether radicals (character components are specified for spatial position in a character (e.g. Ding, Peng, & Taft, 2004; Tsang & Chen, 2009. Differing from previous work, component or radical position information in this study is conceived in terms of relative frequency across different positions of characters containing it. A lexical decision task in a masked priming paradigm focusing on radicals with preferred position of occurrence was conducted. A radical position that encompasses more characters than other positions was identified to be the preferred position of a particular radical. The prime that was exposed for 96ms might share a radical with the target in the same or different positions. Moreover, the shared radical appeared either in its preferred or non-preferred position in the target. While response latencies only revealed the effect of graphical similarity, both effects of graphical similarity and radical position preference were found in the ERP results. The former effect was reflected in greater positivity in occipital P1 and greater negativity in N400 for radicals in different positions in prime and target characters. The latter effect manifested as greater negativity in occipital N170 and greater positivity in frontal P200 in the same time window elicited by radicals in their non-preferred position. Equally interesting was the reversal of the effect of radical position preference in N400 with greater negativity associated with radicals in preferred position. These findings identify the early ERP components associated with activation of position-specific radical representations in the orthographic lexicon, and reveal the change in the nature of competition from processing at the radical level to the lexical level.

  13. Considerations on the mechanism of action of artemisinin antimalarials: part 1--the 'carbon radical' and 'heme' hypotheses.

    Science.gov (United States)

    Haynes, Richard K; Cheu, Kwan-Wing; N'Da, David; Coghi, Paolo; Monti, Diego

    2013-08-01

    peroxide forms heme adducts that apparently inherit the exquisite cytotoxicities of the parent peroxide in one way or another. In a subsequent review, we screen the third and fourth hypotheses: the SERCA hypothesis wherein artemisinins modulate operation of the malaria parasite sarcoendo plasmic reticulum calcium pump SERCA Ca(2+)-ATPase ATP6 and the co-factor hypothesis wherein artemisinins act as oxidant drugs through rapidly oxidizing reduced conjugates of flavin cofactors, or those of flavin cofactor precursors such as riboflavin, and other susceptible endogenous substrates that play a role in maintaining intraparasitic redox homeostasis. For the C-radical hypothesis, details of in vitro chemical studies in the context of established chemistry of C-radicals and their ability to react with radical trapping agents such as nitroso compounds, cyclic nitrones, persistent nitroxyl radicals and atmospheric oxygen (dioxygen) are summarized. Overall, there is no correlation between antimalarial activities and abilities of the derived C-radicals to react with trapping agents in a chemical flask. This applies in particular to the reactions of C-radicals from artemisinins and steroidal tetraoxanes with the trapping agents vis-a-vis those from adamantyl capped systems. In an intraparasitic medium, it is not possible to intercept C-radicals either through use of a vast excess of a nitroxyl radical or dioxygen. The lack of correlation of antimalarial activities also applies to the Fe(2+)-mediated decomposition of artemisinins and synthetic peroxides, where literature data taken as indicating otherwise are critically assessed. The antagonism to antimalarial activities of artemisinins exerted by desferrioxamine (DFO) and related Fe(3+)-chelating agents is due to formation of stable chelates with bioavailable Fe(3+) that shuts down redox cycling through Fe(2+) and the subsequent generation of reactive oxygen species (ROS) via the Fenton reaction. The generation of ROS by Fe(2

  14. Ultraviolet photodissociation dynamics of the benzyl radical.

    Science.gov (United States)

    Song, Yu; Zheng, Xianfeng; Lucas, Michael; Zhang, Jingsong

    2011-05-14

    Ultraviolet (UV) photodissociation dynamics of jet-cooled benzyl radical via the 4(2)B(2) electronically excited state is studied in the photolysis wavelength region of 228 to 270 nm using high-n Rydberg atom time-of-flight (HRTOF) and resonance enhanced multiphoton ionization (REMPI) techniques. In this wavelength region, H-atom photofragment yield (PFY) spectra are obtained using ethylbenzene and benzyl chloride as the precursors of benzyl radical, and they have a broad peak centered around 254 nm and are in a good agreement with the previous UV absorption spectra of benzyl. The H + C(7)H(6) product translational energy distributions, P(E(T))s, are derived from the H-atom TOF spectra. The P(E(T)) distributions peak near 5.5 kcal mol(-1), and the fraction of average translational energy in the total excess energy, , is ∼0.3. The P(E(T))s indicate the production of fulvenallene + H, which was suggested by recent theoretical studies. The H-atom product angular distribution is isotropic, with the anisotropy parameter β ≈ 0. The H/D product ratios from isotope labeling studies using C(6)H(5)CD(2) and C(6)D(5)CH(2) are reasonably close to the statistical H/D ratios, suggesting that the H/D atoms are scrambled in the photodissociation of benzyl. The dissociation mechanism is consistent with internal conversion of the electronically excited benzyl followed by unimolecular decomposition of the hot benzyl radical on the ground state.

  15. Resonance Raman study of benzyl radical

    DEFF Research Database (Denmark)

    Langkilde, F.W.; Bajdor, K.; Wilbrandt, R.

    1992-01-01

    Time-resolved resonance Raman spectra are obtained of benzyl radicals created by laser flash photolysis of benzylchloride and diphenylacetone in solution. The spectra are obtained in resonance with the intense 2 2A2-1 B-2(2) transition of benzyl. The strong Raman bands are assigned to totally...... symmetric a1 modes. The remaining observed bands are tentatively assigned to fundamental modes of b1, a2, and b2 symmetry, and to overtones and combinations. The resonance Raman spectra are found to be quite different from previous fluorescence spectra of benzyl, and the origins of these differences...

  16. Dissociative Photoionization of the Elusive Vinoxy Radical.

    Science.gov (United States)

    Adams, Jonathan D; Scrape, Preston G; Lee, Shih-Huang; Butler, Laurie J

    2017-08-24

    These experiments report the dissociative photoionization of vinoxy radicals to m/z = 15 and 29. In a crossed laser-molecular beam scattering apparatus, we induce C-Cl bond fission in 2-chloroacetaldehyde by photoexcitation at 157 nm. Our velocity measurements, combined with conservation of angular momentum, show that 21% of the C-Cl photofission events form vinoxy radicals that are stable to subsequent dissociation to CH 3 + CO or H + ketene. Photoionization of these stable vinoxy radicals, identified by their velocities, which are momentum-matched with the higher-kinetic-energy Cl atom photofragments, shows that the vinoxy radicals dissociatively photoionize to give signal at m/z = 15 and 29. We calibrated the partial photoionization cross section of vinoxy to CH 3 + relative to the bandwidth-averaged photoionization cross section of the Cl atom at 13.68 eV to put the partial photoionization cross sections on an absolute scale. The resulting bandwidth-averaged partial cross sections are 0.63 and 1.3 Mb at 10.5 and 11.44 eV, respectively. These values are consistent with the upper limit to the cross section estimated from a study by Savee et al. on the O( 3 P) + propene bimolecular reaction. We note that the uncertainty in these values is primarily dependent on the signal attributed to C-Cl primary photofission in the m/z = 35 (Cl + ) time-of-flight data. While the value is a rough estimate, the bandwidth-averaged partial photoionization cross section of vinoxy to HCO + calculated from the signal at m/z = 29 at 11.53 eV is approximately half that of vinoxy to CH 3 + . We also present critical points on the potential energy surface of the vinoxy cation calculated at the G4//B3LYP/6-311++G(3df,2p) level of theory to support the observation of dissociative ionization of vinoxy to both CH 3 + and HCO + .

  17. Processing of free radical damaged DNA bases

    International Nuclear Information System (INIS)

    Wallace, S.

    2003-01-01

    Free radicals produced during the radiolysis of water gives rise to a plethora of DNA damages including single strand breaks, sites of base loss and a wide variety of purine and pyrimidine base lesions. All these damages are processed in cells by base excision repair. The oxidative DNA glycosylases which catalyze the first step in the removal of a base damage during base excision repair evolved primarily to protect the cells from the deleterious mutagenic effects of single free radical-induced DNA lesions arising during oxidative metabolism. This is evidenced by the high spontaneous mutation rate in bacterial mutants lacking the oxidative DNA glycosylases. However, when a low LET photon transverses the DNA molecule, a burst of free radicals is produced during the radiolysis of water that leads to the formation of clustered damages in the DNA molecule, that are recognized by the oxidative DNA glycosylases. When substrates containing two closely opposed sugar damages or base and sugar damages are incubated with the oxidative DNA glycosylases in vitro, one strand is readily incised by the lyase activity of the DNA glycosylase. Whether or not the second strand is incised depends on the distance between the strand break resulting from the incised first strand and the remaining DNA lesion on the other strand. If the lesions are more than two or three base pairs apart, the second strand is readily cleaved by the DNA glycosylase, giving rise to a double strand break. Even if the entire base excision repair system is reconstituted in vitro, whether or not a double strand break ensues depends solely upon the ability of the DNA glycosylase to cleave the second strand. These data predicted that cells deficient in the oxidative DNA glycosylases would be radioresistant while those that overproduce an oxidative DNA glycosylase would be radiosensitive. This prediction was indeed borne in Escherichia coli that is, mutants lacking the oxidative DNA glycosylases are radioresistant

  18. Metal-Diazo Radicals of α-Carbonyl Diazomethanes

    Science.gov (United States)

    Li, Feifei; Xiao, Longqiang; Liu, Lijian

    2016-03-01

    Metal-diazo radicals of α-carbonyl diazomethanes are new members of the radical family and are precursors to metal-carbene radicals. Herein, using electron paramagnetic resonance spectroscopy with spin-trapping, we detect diazo radicals of α-carbonyl diazomethanes, induced by [RhICl(cod)]2, [CoII(por)] and PdCl2, at room temperature. The unique quintet signal of the Rh-diazo radical was observed in measurements of α-carbonyl diazomethane adducts of [RhICl(cod)]2 in the presence of 5,5-dimethyl-pyrroline-1-N-oxide (DMPO). DFT calculations indicated that 97.2% of spin density is localized on the diazo moiety. Co- and Pd-diazo radicals are EPR silent but were captured by DMPO to form spin adducts of DMPO-N• (triplet-of-sextets signal). The spin-trapping also provides a powerful tool for detection of metal-carbene radicals, as evidenced by the DMPO-trapped carbene radicals (DMPO-C•, sextet signal) and 2-methyl-2-nitrosopropane-carbene adducts (MNP-C•, doublet-of-triplets signal). The transformation of α-carbonyl diazomethanes to metal-carbene radicals was confirmed to be a two-step process via metal-diazo radicals.

  19. RNA helicase MOV10 functions as a co-factor of HIV-1 Rev to facilitate Rev/RRE-dependent nuclear export of viral mRNAs

    International Nuclear Information System (INIS)

    Huang, Feng; Zhang, Junsong; Zhang, Yijun; Geng, Guannan; Liang, Juanran; Li, Yingniang; Chen, Jingliang; Liu, Chao; Zhang, Hui

    2015-01-01

    Human immunodeficiency virus type 1 (HIV-1) exploits multiple host factors during its replication. The REV/RRE-dependent nuclear export of unspliced/partially spliced viral transcripts needs the assistance of host proteins. Recent studies have shown that MOV10 overexpression inhibited HIV-1 replication at various steps. However, the endogenous MOV10 was required in certain step(s) of HIV-1 replication. In this report, we found that MOV10 potently enhances the nuclear export of viral mRNAs and subsequently increases the expression of Gag protein and other late products through affecting the Rev/RRE axis. The co-immunoprecipitation analysis indicated that MOV10 interacts with Rev in an RNA-independent manner. The DEAG-box of MOV10 was required for the enhancement of Rev/RRE-dependent nuclear export and the DEAG-box mutant showed a dominant-negative activity. Our data propose that HIV-1 utilizes the anti-viral factor MOV10 to function as a co-factor of Rev and demonstrate the complicated effects of MOV10 on HIV-1 life cycle. - Highlights: • MOV10 can function as a co-factor of HIV-1 Rev. • MOV10 facilitates Rev/RRE-dependent transport of viral mRNAs. • MOV10 interacts with Rev in an RNA-independent manner. • The DEAG-box of MOV10 is required for the enhancement of Rev/RRE-dependent export.

  20. RNA helicase MOV10 functions as a co-factor of HIV-1 Rev to facilitate Rev/RRE-dependent nuclear export of viral mRNAs

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Feng; Zhang, Junsong; Zhang, Yijun; Geng, Guannan; Liang, Juanran; Li, Yingniang; Chen, Jingliang [Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080 (China); Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080 (China); Liu, Chao, E-mail: liuchao9@mail.sysu.edu.cn [Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080 (China); Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080 (China); Zhang, Hui [Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080 (China); Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080 (China)

    2015-12-15

    Human immunodeficiency virus type 1 (HIV-1) exploits multiple host factors during its replication. The REV/RRE-dependent nuclear export of unspliced/partially spliced viral transcripts needs the assistance of host proteins. Recent studies have shown that MOV10 overexpression inhibited HIV-1 replication at various steps. However, the endogenous MOV10 was required in certain step(s) of HIV-1 replication. In this report, we found that MOV10 potently enhances the nuclear export of viral mRNAs and subsequently increases the expression of Gag protein and other late products through affecting the Rev/RRE axis. The co-immunoprecipitation analysis indicated that MOV10 interacts with Rev in an RNA-independent manner. The DEAG-box of MOV10 was required for the enhancement of Rev/RRE-dependent nuclear export and the DEAG-box mutant showed a dominant-negative activity. Our data propose that HIV-1 utilizes the anti-viral factor MOV10 to function as a co-factor of Rev and demonstrate the complicated effects of MOV10 on HIV-1 life cycle. - Highlights: • MOV10 can function as a co-factor of HIV-1 Rev. • MOV10 facilitates Rev/RRE-dependent transport of viral mRNAs. • MOV10 interacts with Rev in an RNA-independent manner. • The DEAG-box of MOV10 is required for the enhancement of Rev/RRE-dependent export.

  1. Peripheral T-Cell Reactivity to Heat Shock Protein 70 and Its Cofactor GrpE from Tropheryma whipplei Is Reduced in Patients with Classical Whipple's Disease.

    Science.gov (United States)

    Trotta, Lucia; Weigt, Kathleen; Schinnerling, Katina; Geelhaar-Karsch, Anika; Oelkers, Gerrit; Biagi, Federico; Corazza, Gino Roberto; Allers, Kristina; Schneider, Thomas; Erben, Ulrike; Moos, Verena

    2017-08-01

    Classical Whipple's disease (CWD) is characterized by the lack of specific Th1 response toward Tropheryma whipplei in genetically predisposed individuals. The cofactor GrpE of heat shock protein 70 (Hsp70) from T. whipplei was previously identified as a B-cell antigen. We tested the capacity of Hsp70 and GrpE to elicit specific proinflammatory T-cell responses. Peripheral mononuclear cells from CWD patients and healthy donors were stimulated with T. whipplei lysate or recombinant GrpE or Hsp70 before levels of CD40L, CD69, perforin, granzyme B, CD107a, and gamma interferon (IFN-γ) were determined in T cells by flow cytometry. Upon stimulation with total bacterial lysate or recombinant GrpE or Hsp70 of T. whipplei , the proportions of activated effector CD4 + T cells, determined as CD40L + IFN-γ + , were significantly lower in patients with CWD than in healthy controls; CD8 + T cells of untreated CWD patients revealed an enhanced activation toward unspecific stimulation and T. whipplei -specific degranulation, although CD69 + IFN-γ + CD8 + T cells were reduced upon stimulation with T. whipplei lysate and recombinant T. whipplei -derived proteins. Hsp70 and its cofactor GrpE are immunogenic in healthy individuals, eliciting effective responses against T. whipplei to control bacterial spreading. The lack of specific T-cell responses against these T. whipplei -derived proteins may contribute to the pathogenesis of CWD. Copyright © 2017 American Society for Microbiology.

  2. Pa2G4 is a novel Six1 co-factor that is required for neural crest and otic development☆

    Science.gov (United States)

    Neilson, Karen M.; Abbruzzesse, Genevieve; Kenyon, Kristy; Bartolo, Vanessa; Krohn, Patrick; Alfandari, Dominique; Moody, Sally A.

    2016-01-01

    Mutations in SIX1 and in its co-factor, EYA1, underlie Branchiootorenal Spectrum disorder (BOS), which is characterized by variable branchial arch, otic and kidney malformations. However, mutations in these two genes are identified in only half of patients. We screened for other potential co-factors, and herein characterize one of them, Pa2G4 (aka Ebp1/Plfap). In human embryonic kidney cells, Pa2G4 binds to Six1 and interferes with the Six1-Eya1 complex. In Xenopus embryos, knock-down of Pa2G4 leads to down-regulation of neural border zone, neural crest and cranial placode genes, and concomitant expansion of neural plate genes. Gain-of-function leads to a broader neural border zone, expanded neural crest and altered cranial placode domains. In loss-of-function assays, the later developing otocyst is reduced in size, which impacts gene expression. In contrast, the size of the otocyst in gain-of-function assays is not changed but the expression domains of several otocyst genes are reduced. Together these findings establish an interaction between Pa2G4 and Six1, and demonstrate that it has an important role in the development of tissues affected in BOS. Thereby, we suggest that pa2g4 is a potential candidate gene for BOS. PMID:27940157

  3. Tentative characterization of precursor compounds and co-factors of pigment formation in production of 'wu mi' from Vaccinium bracteatum Thunb. Leaves.

    Science.gov (United States)

    Fan, Mingcong; Fan, Yihui; Huang, Weiping; Wang, Li; Li, Yan; Qian, Haifeng; Zhang, Hui; Qi, Xiguang

    2018-10-01

    Vaccinium bracteatum leaves (VBTL) are traditionally used in China to dye rice grains, which assume a deep blue color, named 'Wu mi'. Information on the mechanism of pigment formation is limited. In this study, CIELAB color space parameters were used to represent the color of 'Wu mi'. Precursor compounds of pigments formed during the dyeing process were identified by UPLC Q-TOF MS analysis. The changes in co-factors for pigment formation in VBTL were measured at different growth stages. The L ∗ and b ∗ values of dyed rice increased as the leaves aged, whereas a ∗ values showed irregular changes. Six compounds were tentatively identified as pigment precursors by UPLC Q-TOF MS analysis. The pH and β-glucosidase activity at different growth stages of VBTL were indicated to be crucial co-factors for pigment formation. A tentative hypothesis is presented that iridoid glycosides are hydrolyzed by acids and β-glucosidases to form a dialdehyde structure that binds covalently with amino residues of lysine side chains in rice protein molecules. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Spectroscopic evidence for an engineered, catalytically active Trp radical that creates the unique reactivity of lignin peroxidase.

    Science.gov (United States)

    Smith, Andrew T; Doyle, Wendy A; Dorlet, Pierre; Ivancich, Anabella

    2009-09-22

    The surface oxidation site (Trp-171) in lignin peroxidase (LiP) required for the reaction with veratryl alcohol a high-redox-potential (1.4 V) substrate, was engineered into Coprinus cinereus peroxidase (CiP) by introducing a Trp residue into a heme peroxidase that has similar protein fold but lacks this activity. To create the catalytic activity toward veratryl alcohol in CiP, it was necessary to reproduce the Trp site and its negatively charged microenvironment by means of a triple mutation. The resulting D179W+R258E+R272D variant was characterized by multifrequency EPR spectroscopy. The spectra unequivocally showed that a new Trp radical [g values of g(x) = 2.0035(5), g(y) = 2.0027(5), and g(z) = 2.0022(1)] was formed after the [Fe(IV)=O Por(*+)] intermediate, as a result of intramolecular electron transfer between Trp-179 and the porphyrin. Also, the EPR characterization crucially showed that [Fe(IV)=O Trp-179(*)] was the reactive intermediate with veratryl alcohol. Accordingly, our work shows that it is necessary to take into account the physicochemical properties of the radical, fine-tuned by the microenvironment, as well as those of the preceding [Fe(IV)=O Por(*+)] intermediate to engineer a catalytically competent Trp site for a given substrate. Manipulation of the microenvironment of the Trp-171 site in LiP allowed the detection by EPR spectroscopy of the Trp-171(*), for which direct evidence has been missing so far. Our work also highlights the role of Trp residues as tunable redox-active cofactors for enzyme catalysis in the context of peroxidases with a unique reactivity toward recalcitrant substrates that require oxidation potentials not realized at the heme site.

  5. Peroxyl radical reactions with carotenoids in microemulsions: Influence of microemulsion composition and the nature of peroxyl radical precursor.

    Science.gov (United States)

    El-Agamey, Ali; McGarvey, David J

    2016-01-01

    The reactions of acetylperoxyl radicals with different carotenoids (7,7'-dihydro-β-carotene and ζ-carotene) in SDS and CTAC microemulsions of different compositions were investigated using laser flash photolysis (LFP) coupled with kinetic absorption spectroscopy. The primary objective of this study was to explore the influence of microemulsion composition and the type of surfactant used on the yields and kinetics of various transients formed from the reaction of acetylperoxyl radicals with carotenoids. Also, the influence of the site (hydrocarbon phases or aqueous phase) of generation of the peroxyl radical precursor was examined by using 4-acetyl-4-phenylpiperidine hydrochloride (APPHCl) and 1,1-diphenylacetone (11DPA) as water-soluble and lipid-soluble peroxyl radical precursors, respectively. LFP of peroxyl radical precursors with 7,7'-dihydro-β-carotene (77DH) in different microemulsions gives rise to the formation of three distinct transients namely addition radical (λmax=460 nm), near infrared transient1 (NIR, λmax=700 nm) and 7,7'-dihydro-β-carotene radical cation (77DH(•+), λmax=770 nm). In addition, for ζ-carotene (ZETA) two transients (near infrared transient1 (NIR1, λmax=660 nm) and ζ-carotene radical cation (ZETA(•+), λmax=730-740 nm)) are generated following LFP of peroxyl radical precursors in the presence of ζ-carotene (ZETA) in different microemulsions. The results show that the composition of the microemulsion strongly influences the observed yield and kinetics of the transients formed from the reactions of peroxyl radicals (acetylperoxyl radicals) with carotenoids (77DH and ZETA). Also, the type of surfactant used in the microemulsions influences the yield of the transients formed. The dependence of the transient yields and kinetics on microemulsion composition (or the type of surfactant used in the microemulsion) can be attributed to the change of the polarity of the microenvironment of the carotenoid. Furthermore, the nature of

  6. NOx removal characteristics of corona radical shower with ammonia and methylamine radical injections

    Energy Technology Data Exchange (ETDEWEB)

    Urashima, K.; Ara, M.; Chang, J.S. [McMaster Univ., Hamilton, ON (Canada). Dept. of Engineering Physics; Uchida, Y. [Aichi Inst. of Technology, (Japan). Dept. of Engineering

    2010-07-01

    Air pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) are the major cause of acid rain. There are different types of NOx and SOx conversion techniques such as wet scrubber, selective catalytic reactor, sorbent injection, and low NOx burner. Non-thermal plasma techniques have also been utilized in commercial plants, but the energy efficiency of the non-thermal plasma reactors have not yet been optimized. The direct plasma treatments of flue gases including, the electron beam, barrier discharge and pulsed corona reactors, may lose input energy to activate unwanted components of flue gases such as carbon dioxide (CO{sub 2}) and nitrogen (N{sub 2}). The corona discharge ammonia radical shower system has demonstrated significant NOx removal with higher energy efficiency for large bench scale and pilot plant tests for combustion exhausts. An experiment has also demonstrated that methane can replace ammonia as an injection gas with less NOx removal efficiency. This paper presented an experimental investigation that compared methylamine radical injection with traditional ammonia and methane radical injections. The paper discussed the bench scale test facilities and corona radical shower plasma reactor. It was concluded that the processes to form ammonium nitrate could be observed from trace white solid particles deposited on the reactor wall as observed by scanning electron microscopy pictures. 10 refs., 5 figs., 2 appendices.

  7. Encapsulation of Gibbsite platelets with free radical and controlled radical emulsion polymerization approaches, a small review

    NARCIS (Netherlands)

    Loiko, O.P.; Spoelstra, A.B.; van Herk, A.M.; Meuldijk, J.; Heuts, J.P.A.

    2016-01-01

    Water-borne anisotropic polymer-Gibbsite latex particles were prepared by a conventional and an atom transfer radical polymerisation (ATRP) based starved-feed emulsion polymerisation without any chemical modification of the platelet surface. Anionic co-oligomers, synthesised via ATRP, were used in

  8. Nitroxide-mediated controlled radical polymerisation: towards control of molar mass Controlled Radical Polymerisation

    NARCIS (Netherlands)

    Bon, S.A.F.; Bergman, F.A.C.; Es, van J.J.G.S.; Klumperman, B.; German, A.L.; Matyjaszewski, K.

    1998-01-01

    The mechanism of the TEMPO-mediated controlled radical polymerization of styrene in bulk is discussed. It is shown that the isotropic correlation time (tc) of a nitroxide can be used as a measure of the diffusive rate coefficient of trapping (ketD). A general empirical relationship for the density

  9. Electron spin resonance spectroscopy of organic radicals spectroscopy of organic radicals

    CERN Document Server

    Gerson, Fabian

    2006-01-01

    ""This book should serve as a comprehensive one-volume source for finding what is known about the splitting constants and g factors of virtually all types of organic radicals."" Journal of the American Chemistry Society, 2004, Vol. 126 No. 20

  10. Hydrogen Radicals, Nitrogen Radicals, and the Production of Ozone in the Middle and Upper Troposphere

    Science.gov (United States)

    Bui, T. P.

    1997-01-01

    The concentrations of hydrogen radicals, OH and HO2, in the middle and upper troposphere were measured simultaneously with those of NO, O3,CO, H20, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field.

  11. Radical constructivism and radical constructedness: Luhmann's sociology of semantics, organizations, and self-organization

    NARCIS (Netherlands)

    Leydesdorff, L.

    2012-01-01

    Context: Using radical constructivism, society can be considered from the perspective of asking the question, "Who conceives of society?" In Luhmann’s social systems theory, this question itself is considered as a construct of the communication among reflexive agents. Problem: Structuration of

  12. COST Action CM1201 "Biomimetic Radical Chemistry": free radical chemistry successfully meets many disciplines

    Czech Academy of Sciences Publication Activity Database

    Ferreri, C.; Golding, B. T.; Jahn, Ullrich; Ravanat, J. L.

    2016-01-01

    Roč. 50, Suppl 1 (2016), S112-S128 ISSN 1071-5762 Institutional support: RVO:61388963 Keywords : radical enzyme * membrane stress * phospholipid remodeling * DNA damage and repair * biomimetic models * bio-inspired synthetic methodologies Subject RIV: CC - Organic Chemistry Impact factor: 3.188, year: 2016 http://www.tandfonline.com/doi/full/10.1080/10715762.2016.1248961

  13. The mitochondrial free radical theory of aging.

    Science.gov (United States)

    Barja, Gustavo

    2014-01-01

    The mitochondrial free radical theory of aging is reviewed. Only two parameters currently correlate with species longevity in the right sense: the mitochondrial rate of reactive oxygen species (mitROS) production and the degree of fatty acid unsaturation of tissue membranes. Both are low in long-lived animals. In addition, the best-known manipulation that extends longevity, dietary restriction, also decreases the rate of mitROS production and oxidative damage to mtDNA. The same occurs during protein restriction as well as during methionine restriction. These two manipulations also increase maximum longevity in rodents. The decrease in mitROS generation and oxidative stress that takes place in caloric restriction seems to be due to restriction of a single dietary substance: methionine. The information available supports a mitochondrial free radical theory of aging focused on low generation of endogenous damage and low sensitivity of membranes to oxidation in long-lived animals. © 2014 Elsevier Inc. All rights reserved.

  14. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, Douglas Robert [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward.

  15. Radical reactions in vivo - an overview

    International Nuclear Information System (INIS)

    Saran, M.; Bors, W.

    1990-01-01

    Generation of radicals in vivo depends on metabolic activities. The reactions are usually influenced by (i) the presence and concentration of oxygen, (ii) the availability of transition metals (effects of binding and compartimentalization), (iii) the level of reductants and antioxidants (e.g. nutritional effects). The effects of radicals are thought to be due to (i) membrane damage (affecting passive or active transport through altered fluidity/function interrelationships, intercellular messenging through modifications in the synthesis of prostaglandins and leukotrienes); (ii) protein damage (e.g. affecting membrane transporters, channel proteins, receptor or regulatory proteins, immunomodulators); (iii) damage to DNA. Defense mechanisms consist of (i) prevention of the 'spreading' of primary damage by low molecular weight antioxidants (e.g. vitamin E, GSH, vitamin C, β-carotene, uric acid); (ii) prevention or limitation of 'secondary' damage by enzymes (e.g. GSH-peroxidase, catalase, superoxide dismutase, DT-diaphorase) and/or chelators; (iii) repair processes, e.g. lipid degradation/membrane repair enzymes (phospholipases, peroxidases, some transferases and reductases), protein disposal or repair enzymes (proteases, GSSG-reductase), DNA degradation or repair enzymes (exonucleases III, endonucleases III and IV, glycosylases, polymerases). Recent hypotheses on a messenging function of the superoxide anion O 2 - are discussed and possible implications of cross-reactions between O 2 - and nitric oxide (endothelium-derived relaxing factor EDRF) are shortly mentioned. (orig.)

  16. The Rovibronic Spectra of the Cyclopentadienyl Radical

    Science.gov (United States)

    Sharma, Ketan; Miller, Terry A.; Stanton, John F.; Nesbitt, David

    2017-06-01

    Cyclopentadienyl (Cp) radical has been subject to numerous studies for the greater part of half a century. Experimental work has involved photo-electron spectroscopy, laser induced fluorescence excitation and emission, infrared absorption spectroscopy, and recently rotationally resolved spectra in the CH stretch region taken at JILA. Even more theoretical works appear in the literature, but substantial advances in computation have occurred since their completion. Cp's highly symmetric (D_{5h}) structure and doubly degenerate electronic ground (˜{X}^2E_1^{''}), which is subject to linear Jahn-Teller distortion, have been a great motivation for work on it. We have commenced new computational work to obtain a broad understanding of the electronic, vibrational, and rotational, i.e. rovibronic, structure of the Cp radical as revealed by its spectra, with particular emphasis on the new infrared spectra. The goal is to guide experiments and their analyses and reconcile results from spectroscopy and quantum chemistry calculations. T. Ichino, et al. J. Chem. Phys. 129, 084310 (2008) L. Yu, S. C. Foster, J. M. Williamson, M. C. Heaven and T. A. Miller J. Phys. Chem. 92, 4263 (1988) B. E. Applegate, A. J. Bezant and T. A. Miller J. Chem. Phys 114, 4869 (2001) D. Leicht, M. Kaufmann, G. Schwaab, and M. Havenith J. Chem. Phys. 145, 7 (2016), 074304.

  17. Mechanisms of radical removal by SO2

    DEFF Research Database (Denmark)

    Rasmussen, Christian Lund; Glarborg, Peter; Marshall, Paul

    2007-01-01

    It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H......(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find...... that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H...

  18. Free Radicals and Extrinsic Skin Aging

    Directory of Open Access Journals (Sweden)

    Borut Poljšak

    2012-01-01

    Full Text Available Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR. It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2−•, hydrogen peroxide (H2O2, hydroxyl radical (OH•, and singlet oxygen (1O2. The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants and antioxidants we consume from the food (vitamin A, C, E, etc.. The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

  19. Nitrate radicals and biogenic volatile organic compounds ...

    Science.gov (United States)

    Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO3-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Despite its long history of research and the significance of this topic in atmospheric chemistry, a number of important uncertainties remain. These include an incomplete understanding of the rates, mechanisms, and organic aerosol yields for NO3-BVOC reactions, lack of constraints on the role of heterogeneous oxidative processes associated with the NO3 radical, the difficulty of characterizing the spatial distributions of BVOC and NO3 within the poorly mixed nocturnal atmosphere, and the challenge of constructing appropriate boundary layer schemes and non-photochemical mechanisms for use in state-of-the-art chemical transport and chemistry–climate models. This review is the result of a workshop of the same title held at the Georgia Institute of Technology in June 2015. The first half of the review summarizes the current literature on NO3-BVOC chemistry, with a particular focus on recent advances in

  20. Radical cystectomy: Analysis of postoperative course

    Directory of Open Access Journals (Sweden)

    Jeremić Dimitrije

    2010-01-01

    Full Text Available Background/Aim. Radical cystectomy is a method of choice in the therapy of infiltrative bladder cancer. The aim of this research was to analyze postoperative course after radical cystectomy (length of hospitalization, most frequent complications and utilization of antibiotics and transfusions. Methods. We analyzed the records of 82 patients operated on in the Department of Urology, Clinical Center of Vojvodina, in a three-year period. In order to aquire data World Health Organization (WHO has developed Anatomical Therapeutic Chemical/Defined Daily Dose (ATC/DDD methodology. Defined daily dose (DDD is the assumed average maintenance dose per day for a drug use for its main indication. Results. Continent urinary derivation was preformed in 23.15% cases. Postoperative complications occurred in 18.29% of patients. Average blood utilization was 2.19 units. Blood utilization for continent derivations (n = 48 was 4.6 units, and incontinent ones 3.36 units. Totally 159.33 DDD/100 bed days were used. Conclusion. When preforming continent derivation there is a significant increase in blood utilization. Frequency of postoperative complications correlates to those reported in the literature.

  1. Hydroxyl radical induced degradation of ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Illés, Erzsébet, E-mail: erzsebet.illes@chem.u-szeged.hu [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Takács, Erzsébet [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Dombi, András [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Gajda-Schrantz, Krisztina [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged (Hungary); EMPA, Laboratory for High Performance Ceramics, Duebendorf (Switzerland); Rácz, Gergely; Gonter, Katalin; Wojnárovits, László [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary)

    2013-03-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm{sup −3}. For end product characterization {sup 60}Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of {sup ·}OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation.

  2. Fast beam studies of free radical photodissociation

    International Nuclear Information System (INIS)

    Cyr, D.R.; California Univ., Berkeley, CA

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward

  3. Ascorbyl radical disproportionation in reverse micellar systems

    Science.gov (United States)

    Gębicki, J. L.; Szymańska-Owczarek, M.; Pacholczyk-Sienicka, B.; Jankowski, S.

    2018-04-01

    Ascorbyl radical was generated by the pulse radiolysis method and observed with the fast kinetic spectrophotometry within reverse micelles stabilized by AOT in n-heptane or by Igepal CO-520 in cyclohexane at different water to surfactant molar ratio, w0. Rate constants for the disproportionation of the ascorbyl radicals were smaller than those for intermicellar exchange for both type of reverse micelles and slower than those in homogeneous aqueous solutions. However, they increased with increasing w0 for AOT/n-heptane system, while they decreased for Igepal CO-520 system. The absorption spectra of ascorbic acid AOT/n-heptane reverse micellar system showed that the "pH" sensed by this molecule is lower than that in respective homogeneous aqueous solutions. The obtained results were rationalized taking into account three main factors (i) preferential location of ascorbic acid molecules in the interfacial region of the both types of reverse micelles; (ii) postulate that the pH of the interface is lower than that of the water pool of reverse micelles and (iii) different structure of the interface of the reverse micelles made by AOT in n-heptane and those formed by Igepal CO-520 I cyclohexane. Some possible consequences of these findings are discussed.

  4. The Prospects of Radical Change Today

    Directory of Open Access Journals (Sweden)

    Slavoj Žižek

    2018-05-01

    Full Text Available In this contribution, Slavoj Žižek takes the occasion of Marx’s bicentenary for reflecting on the prospects of radical change today. First, it is shown that under Stalinism, Lenin’s works were quoted out of context in an arbitrary way in order to legitimise arbitrary political measures. Marxism thereby became an ideology that justified brutal subjective interventions. Second, this contribution poses the question of the revolutionary subject and democracy today. It stresses the role of both contingency and strategy in revolutions. In political assemblages taking place on public squares, the inert mass of ordinary people is transubstantiated into a politically engaged united force. The basic political problem today is how to best reconfigure democracy. Third, this contribution analyses the “interesting times” we live in. These are times that feature multiple crises, right-wing populism à la Donald Trump and Marine Le Pen, the lower classes’ opposition to immigration, and the refugee crisis. Questions about human rights and their violation and about radical change need to be asked in this context.

  5. Hegel’s Gesture Towards Radical Cosmopolitanism

    Directory of Open Access Journals (Sweden)

    Shannon Brincat

    2009-09-01

    Full Text Available This is a preliminary argument of a much larger research project inquiring into the relation betweenHegel’s philosophical system and the project of emancipation in Critical International Relations Theory. Specifically, the paper examines how Hegel’s theory of recognition gestures towards a form of radical cosmopolitanism in world politics to ensure the conditions of rational freedom for all humankind. Much of the paper is a ground-clearing exercise defining what is ‘living’ in Hegel’s thought for emancipatory approaches in world politics, to borrow from Croce’s now famous question. It focuses on Hegel’s unique concept of freedom which places recognition as central in the formation of self-consciousness and therefore as a key determinant in the conditions necessary forhuman freedom to emerge in political community. While further research is needed to ascertain the precise relationship between Hegel’s recognition theoretic, emancipation and cosmopolitanism, it is contended that the intersubjective basis of Hegel’s concept of freedom through recognition necessitates some form of radical cosmopolitanism that ensures successful processes of recognition between all peoples, the precise institutional form of which remains unspecified.

  6. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying 2Σ and 2π states of C2nH (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C2H and C4H. Other radicals studied include NCN and I3. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I3 revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  7. Hydroxyl radical induced degradation of ibuprofen

    International Nuclear Information System (INIS)

    Illés, Erzsébet; Takács, Erzsébet; Dombi, András; Gajda-Schrantz, Krisztina; Rácz, Gergely; Gonter, Katalin; Wojnárovits, László

    2013-01-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm −3 . For end product characterization 60 Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of · OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation

  8. Radicals of DNA and DNA nucleotides generated by ionising radiation

    International Nuclear Information System (INIS)

    Przybytniak, G.

    2004-01-01

    A first stage of cell processes leading to DNA damage of initiated by radical reactions. In a model system such transformations were generated by ionising radiation which involves production of electron loss and electron gain centers of the substrate and radical formation. Using cryogenic ESR spectroscopy it was found that the DNA nucleotides, which convert to radical anions upon electron capture undergo the separation of unpaired spin and charge due to protonation. Circular and linear dichroism studies enabled to conclude that iron ions(III) induce strong changes in the DNA helical structure indicating their coordination with nitrogen bases. The repair of DNA radicals produced via radiolytic oxidation, i.e. the guanine radical cation and the allyl type radical of thymine, is possible at elevated temperatures due to the involvement of sulphydryl groups. The influence of the thiol charge is then limited

  9. Acyclic diastereoselection in prochiral radical addition to prochiral olefins.

    Science.gov (United States)

    Sibi, Mukund P; Rheault, Tara R; Chandramouli, Sithamalli V; Jasperse, Craig P

    2002-03-27

    The stereochemical preference (syn or anti) when prochiral radicals add to prochiral acceptors is of fundamental interest. The primary focus of this research was to determine which factors influence the relative stereochemistry between the beta and gamma chiral centers when these are formed concurrently. While moderate diastereoselectivity was found for addition of alkyl (6a-d) and alpha-alkoxy radicals (16a-c) (15:1 anti). Steric influence in alkyl radical additions was difficult to evaluate due to decreased reactivity when using bulky reaction partners; however, more reactive alpha-alkoxy radicals, it was found that increasing steric bulk leads to moderate increases in selectivity. In addition, higher selectivity was observed when employing lanthanide Lewis acids whose environment (reactivity) was modified using achiral additives, suggesting a potentially simple means for selectivity enhancements in radical reactions. Overall these results indicate that significant stereoelectronic effects are necessary to achieve high levels of selectivity in prochiral radical additions to prochiral acceptors.

  10. Measurements of hydroxyl and hydroperoxy radicals during CalNex-LA: Model comparisons and radical budgets

    Science.gov (United States)

    Griffith, S. M.; Hansen, R. F.; Dusanter, S.; Michoud, V.; Gilman, J. B.; Kuster, W. C.; Veres, P. R.; Graus, M.; de Gouw, J. A.; Roberts, J.; Young, C.; Washenfelder, R.; Brown, S. S.; Thalman, R.; Waxman, E.; Volkamer, R.; Tsai, C.; Stutz, J.; Flynn, J. H.; Grossberg, N.; Lefer, B.; Alvarez, S. L.; Rappenglueck, B.; Mielke, L. H.; Osthoff, H. D.; Stevens, P. S.

    2016-04-01

    Measurements of hydroxyl (OH) and hydroperoxy (HO2*) radical concentrations were made at the Pasadena ground site during the CalNex-LA 2010 campaign using the laser-induced fluorescence-fluorescence assay by gas expansion technique. The measured concentrations of OH and HO2* exhibited a distinct weekend effect, with higher radical concentrations observed on the weekends corresponding to lower levels of nitrogen oxides (NOx). The radical measurements were compared to results from a zero-dimensional model using the Regional Atmospheric Chemical Mechanism-2 constrained by NOx and other measured trace gases. The chemical model overpredicted measured OH concentrations during the weekends by a factor of approximately 1.4 ± 0.3 (1σ), but the agreement was better during the weekdays (ratio of 1.0 ± 0.2). Model predicted HO2* concentrations underpredicted by a factor of 1.3 ± 0.2 on the weekends, while measured weekday concentrations were underpredicted by a factor of 3.0 ± 0.5. However, increasing the modeled OH reactivity to match the measured total OH reactivity improved the overall agreement for both OH and HO2* on all days. A radical budget analysis suggests that photolysis of carbonyls and formaldehyde together accounted for approximately 40% of radical initiation with photolysis of nitrous acid accounting for 30% at the measurement height and ozone photolysis contributing less than 20%. An analysis of the ozone production sensitivity reveals that during the week, ozone production was limited by volatile organic compounds throughout the day during the campaign but NOx limited during the afternoon on the weekends.

  11. [Radicalism and feminism: The case of Poulain de la Barre].

    Science.gov (United States)

    Pellegrin, Marie-Frédérique

    2015-12-01

    Early modern radicalism and its criteria are described and defined by Jonathan Israel in various works. Poulain de la Barre, one of the first modern feminist thinkers, first is used by Israel as an example of the so-called radical Enlightenment and finally is rejected as such. This case study exhibed the necessity of questionning the coherence of the required criteria for defining a « radical » thinker, especially when examinating carefully the last paragraph of Spinoza's Political Treatise.

  12. Copper-catalyzed radical carbooxygenation: alkylation and alkoxylation of styrenes.

    Science.gov (United States)

    Liao, Zhixiong; Yi, Hong; Li, Zheng; Fan, Chao; Zhang, Xu; Liu, Jie; Deng, Zixin; Lei, Aiwen

    2015-01-01

    A simple copper-catalyzed direct radical carbooxygenation of styrenes is developed utilizing alkyl bromides as radical resources. This catalytic radical difunctionalization accomplishes both alkylation and alkoxylation of styrenes in one pot. A broad range of styrenes and alcohols are well tolerated in this transformation. The EPR experiment shows that alkyl halides could oxidize Cu(I) to Cu(II) in this transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Radical polarization in double switching of external magnetic field

    International Nuclear Information System (INIS)

    Lukzen, N.N.; Morozov, V.A.; Sagdeev, R.Z.

    1999-01-01

    Theoretical treatment of radical spin evolution under the action of double switching of external magnetic field is proposed. Account is taken of evolution of the radical spin state during laser pulse which generates paramagnetic particles. It is shown that the most effective beats in the nuclear magnetization of diamagnetic products of recombination occur upon the jump into zero magnetic field after laser pulse. The phase of observed beats bears information about the type of the initial radical polarization. The frequency of the beats is determined by radical hyperfine structure. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  14. The research progress of several kinds of free radical scavengers

    International Nuclear Information System (INIS)

    Qian Liren; Huang Yuecheng; Cai Jianming

    2009-01-01

    Ionization radiation can generate free radicals in biological system, which could induce lipid peroxi-dation, biomacromolecule and biomembrane damage, lost of cell function, cell cycle disturbance, genetic mutation and so on. The scavenging free radicals can protect organism from radiation damage. Many radio-protective agents, such as amylase, hydroxyl-benzene derivatives, hormone, vitamin, have great abilities to protect organism from radiation via scavenging free radicals. In this paper, we mainly review the free radical scavenging effects of several kinds of radio-protective agents. (authors)

  15. Progress on resonance ionization detection of combustion radicals

    International Nuclear Information System (INIS)

    Cool, T.A.

    1994-01-01

    Selective laser ionization techniques are used in our laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames. The progress made on the following three separate experiments during the past year is briefly described in this report. Flame Radical Concentration Measurements with VUV Spectroscopy; observation of hyperfine quantum beats in cyanogen; and the spectroscopy of the ClCO radical

  16. Incontinence and Erectile Dysfunction Following Radical Prostatectomy: A Review

    Directory of Open Access Journals (Sweden)

    Gerasimos Alivizatos

    2005-01-01

    Full Text Available Radical prostatectomy remains the treatment of choice for localized prostate cancer in age-appropriate and health-appropriate men. Although cancer control is the most important aspect of a radical prostatectomy, minimization of postoperative morbidity, especially urinary incontinence and erectile dysfunction, is becoming a greater concern. We reviewed recent data available on Medline regarding the incidence, pathophysiology, evaluation, and treatment of incontinence and sexual dysfunction after radical prostatectomy. Health-related quality of life issues have been specifically addressed. Although low incidences of incontinence and erectile dysfunction after radical prostatectomy have been reported in the hands of experienced surgeons, the literature review revealed a great variety, with incontinence rates ranging from 0.3–65.6% and potency rates ranging from 11–87%. Several factors contribute to this wide difference, the most important being the application of a meticulous surgical technique. General and cancer-specific health-related quality of life is not being affected after radical prostatectomy. The incidence of incontinence and erectile dysfunction is higher after radical prostatectomy when compared to the incidence observed when other therapies for localized prostate cancer are applied. However, the majority of the patients undergoing radical prostatectomy would vote for the operation again. Today, avoidance of major complications after radical prostatectomy depends mostly on a high-quality surgical technique. When incontinence or erectile dysfunction persists after radical prostatectomy, the majority of the treated patients can be managed effectively by various methods.

  17. Co-ordinate variations in methylmalonyl-CoA mutase and methionine synthase, and the cobalamin cofactors in human glioma cells during nitrous oxide exposure and the subsequent recovery phase.

    Science.gov (United States)

    Riedel, B; Fiskerstrand, T; Refsum, H; Ueland, P M

    1999-07-01

    We investigated the co-ordinate variations of the two cobalamin (Cbl)-dependent enzymes, methionine synthase (MS) and methylmalonyl-CoA mutase (MCM), and measured the levels of their respective cofactors, methylcobalamin (CH3Cbl) and adenosylcobalamin (AdoCbl) in cultured human glioma cells during nitrous oxide exposure and during a subsequent recovery period of culture in a nitrous oxide-free atmosphere (air). In agreement with published data, MS as the primary target of nitrous oxide was inactivated rapidly (initial rate of 0.06 h(-1)), followed by reduction of CH3Cbl (to ordinate distribution of Cbl cofactors during depletion and repletion.

  18. Oxidation of aromatic amines and diamines by OH radicals. Formation and ionization constants of amine cation radicals in water

    International Nuclear Information System (INIS)

    Hayon, E.; Rao, P.S.

    1975-01-01

    The one-electron oxidation by hydroxyl radicals of aromatic amines and diamines in water was studied using the fast-reaction technique of pulse radiolysis and kinetic absorption spectrophotometry. The following compounds were examined: N,N,N 1 ,N 1 - tetramethyl-p-phenylenediamine (TMPD), p-phenylenediamine (PD), N,N-dimethyl-p-phenylenediamene (DMPD), N,N,N 1 ,N 1 -tetramethylbenzidine (TMB), and diphenylamine (DPA). The main initial reaction of the OH radicals is suggested to be an addition to these compounds to give absorption spectra which absorb strongly in the visible and uv regions. These OH radical adducts decay by first-order kinetics and have lifetimes of approximately 5-50 μsec, dependent on the pH, buffer concentration, and the nature of the aromatic amines and diamines. They decay to give species with somewhat similar absorption spectra and extinction coefficients, which are very long lived in the absence of oxygen. The latter species are assigned to the cation radicals TMPD. + , PD. + , DMPD. + , TMB. + , and DPA. + . The OH radical adducts and the cation radicals have acid-base properties. The pK/sub a/ values of the cation radicals TMPDH. 2+ , PDH. 2+ , DMPDH. 2+ , TMBH. 2+ , and DPAH. 2+ were found to be 5.3, 5.9, 6.1, 5.1, and 4.2, respectively. The results indicate that these aromatic amines and diamines can be oxidized by free radicals to yield the corresponding cation radicals. (U.S.)

  19. CRITICAL THEORY OF THE RADICAL LOVE

    Directory of Open Access Journals (Sweden)

    Lena de Botton

    2009-11-01

    Full Text Available The understanding of the sexual-affective relationships has historically notbeen tackled by science, but placed in the context of instincts and irrationality. In thissense, the critical theory of the Radical Love provides a contribution to critical pedagogyallowing people to understand the mechanisms that direct their emotions and theprocess of election in the sexual-affective relationships. It is about understanding whodo we fall in love for, why and to which values is this desire linked being able to have agreat repercussion in our lives as it provides us with the tools to develop satisfactorysexual-affective relationships. It also offers us guidelines for a preventive educationregarding gender violence by enabling us to understand the attraction models in whichwe have been socialised and which are influencing our desire and elections.

  20. DEMOCRACIA RADICAL Y CIUDADANÍA

    Directory of Open Access Journals (Sweden)

    Pedro Pablo Serna

    2008-01-01

    Full Text Available En el presente texto se presentan dos miradas con respecto a la democracia y su relación con el pensamiento liberal, mostrando de manera específica las características principales de la democracia radical y la manera como ésta puede realizar un adecuado encuentro entre lo individual y lo social, sin afectar las garantías mínimas que se le deben dar a todos los individuos para la realización de su propia concepción de bien. Debe propiciar también unas condiciones adecuadas de participación y control sobre lo público. Para ello, mostraré las visiones de Hayek y Nozick, confrontadas con la mirada de autores como Mouffe, Fraser y otros, quienes proponen un sentido viable, más amplio e incluyente de democracia.

  1. Spectroscopy, Kinetics, and Dynamics of Combustion Radicals

    Energy Technology Data Exchange (ETDEWEB)

    Nesbitt, David J. [Research/Professor

    2013-08-06

    Spectroscopy, kinetics and dynamics of jet cooled hydrocarbon transients relevant to the DOE combustion mission have been explored, exploiting i) high resolution IR lasers, ii) slit discharge sources for formation of jet cooled radicals, and iii) high sensitivity detection with direct laser absorption methods and near the quantum shot noise limit. What makes this combination powerful is that such transients can be made under high concentrations and pressures characteristic of actual combustion conditions, and yet with the resulting species rapidly cooled (T ≈10-15K) in the slit supersonic expansion. Combined with the power of IR laser absorption methods, this provides novel access to spectral detection and study of many critical combustion species.

  2. Schoenberg and the Radical Economies of Harmonielehre

    Directory of Open Access Journals (Sweden)

    Murray Dineen

    2009-06-01

    Full Text Available This article examines Schoenberg’s Harmonielehre as a text shaped by the influence of Central European science and politics. In accord with a severely economical approach to his subject, Schoenberg’s critique of figured bass and chorale harmonization is compared with Ernst Mach’s writings on scientific method. In support of this comparison, the article addresses the role played in Schoenberg’s political development by the Leftist editor and organizer, David J. Bach, one of Schoenberg’s closest childhood friends and a student of Mach. The comparison between Schoenberg and Mach, then, is drawn not only in terms of scientific method but also in light of the radical politics of the Austrian Left at the time, a politics for which both Mach and Schoenberg held sympathies. It should not be overlooked that later, however, they ceased to acknowledge these sympathies explicitly, and Schoenberg would appear to have abandoned them entirely.

  3. CN radical in diffuse interstellar clouds

    International Nuclear Information System (INIS)

    Federman, S.R.; Danks, A.C.; Lambert, D.L.

    1984-01-01

    A survey of 15 lines of sight for the CN B 2 Σ + --X 2 Σ + interstellar absorption lines shows that the CN column density in diffuse interstellar clouds follows the relation log N(CN)proportionalm log N(H 2 ), where mroughly-equal3. This result is reproduced by a reaction network in which CN is produced primarily from C 2 by the neutral-neutral reaction C 2 +N → CN+C, and photodissociation is the main destruction pathway for the neutral molecules CH, C 2 , and CN. The CN radical is the first molecular species observed in diffuse clouds that requires a neutral-neutral reaction for its formation in the gas phase. The network also reproduces the observed ratio N(CN)/N(H 2 )

  4. ESR study of free radicals in mango

    Science.gov (United States)

    Kikuchi, Masahiro; Hussain, Mohammad S.; Morishita, Norio; Ukai, Mitsuko; Kobayashi, Yasuhiko; Shimoyama, Yuhei

    2010-01-01

    An electron spin resonance (ESR) spectroscopic study of radicals induced in irradiated fresh mangoes was performed. Mangoes in the fresh state were irradiated with γ-rays, lyophilized and then crushed into a powder. The ESR spectrum of the powder showed a strong main peak at g = 2.004 and a pair of peaks centered at the main peak. The main peak was detected from both flesh and skin specimens. This peak height gradually decreased during storage following irradiation. On the other hand, the side peaks showed a well-defined dose-response relationship even at 9 days post-irradiation. The side peaks therefore provide a useful means to define the irradiation of fresh mangoes.

  5. Intramolecular hydrogen bonding in malonaldehyde and its radical analogues.

    Science.gov (United States)

    Lin, Chen; Kumar, Manoj; Finney, Brian A; Francisco, Joseph S

    2017-09-28

    High level Brueckner doubles with triples correction method-based ab initio calculations have been used to investigate the nature of intramolecular hydrogen bonding and intramolecular hydrogen atom transfer in cis-malonaldehyde (MA) and its radical analogues. The radicals considered here are the ones that correspond to the homolytic cleavage of C-H bonds in cis-MA. The results suggest that cis-MA and its radical analogues, cis-MA RS , and cis-MA RA , both exist in planar geometry. The calculated intramolecular O-H⋯O=C bond in cis-MA is shorter than that in the radical analogues. The intramolecular hydrogen bond in cis-MA is stronger than in its radicals by at least 3.0 kcal/mol. The stability of a cis-malonaldehyde radical correlates with the extent of electron spin delocalization; cis-MA RA , in which the radical spin is more delocalized, is the most stable MA radical, whereas cis-MA RS , in which the radical spin is strongly localized, is the least stable radical. The natural bond orbital analysis indicates that the intramolecular hydrogen bonding (O⋯H⋯O) in cis-malonaldehyde radicals is stabilized by the interaction between the lone pair orbitals of donor oxygen and the σ * orbital of acceptor O-H bond (n → σ * OH ). The calculated barriers indicate that the intramolecular proton transfer in cis-MA involves 2.2 kcal/mol lower barrier than that in cis-MA RS .

  6. Radical radiotherapy for T3 laryngeal cancers

    Energy Technology Data Exchange (ETDEWEB)

    Uno, T. [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy; Itami, J. [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy; Kotaka, K. [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy; Toriyama, M. [International Medical Center of Japan, Tokyo (Japan). Dept. of Otolaryngology

    1996-08-01

    From 1974 through 1992, 37 previously untreated patients with T3 laryngeal cancer (supraglottic 15, glottic 22) were treated with initial radical radiotherapy and surgery for salvage. Two-year local control rate with radiotherapy alone, ultimate voice preservation rate, and ultimate local control rate for T3 supraglottic cancer were 33%, 33%, and 60%, respectively. Corresponding figures for T3 glottic cancer were 32%, 23%, and 77%, respecitvely. Five-year cause-specific survival rate for T3 supraglottic cancer and glottic cancer were 47% and 77%, respectively. In T3 supraglottic cancer, none of the 4 patients with subglottic tumor extension attained local control by radiotherapy alone, and local-regional recurrence-free time were significantly shorter in patients with subglottic tumor extension or tracheostomy before radiotherapy. There were no serious late complications such as chondronecrosis, rupture of carotid artery attributed to radical radiotherapy, while 3 patients had severe laryngeal edema requiring total laryngectomy. (orig.) [Deutsch] Von 1974 bis 1992 wurden 37 zuvor nicht behandelte Patienten mit T3-Larynxkarzinomen (15 supraglottisch, 22 glottisch) primaer kurativ bestrahlt und, wenn erforderlich, einer Salvage-Operation unterzogen. Die Zwei-Jahres-Kontrollrate bei alleiniger Strahlentherapie, die Rate der Stimmerhaltung sowie die unter Einschluss der Operation erreichbare lokale Kontrollrate bei supraglottischen T3-Larynxkarzinomen betrugen 33%, 33% und 60%. Bei glottischen T3-Karzinomen wurden jeweils 32%, 23% und 77% erreicht. Die Fuenf-Jahres-Ueberlebensrate betrug 47% bei supraglottischen T3-Karzinomen und 77% bei den glottischen Karzinomen. Im Fall von supraglottischen Karzinomen erreichte keiner der vier Patienten mit subglottischer Tumorausdehnung eine lokale Kontrolle durch alleinige Strahlentherapie. Die lokoregionale rezidivfreie Zeit war bei den Patienten mit subglottischer Tumorausdehnung oder Tracheostomie vor Einleitung der

  7. Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

    DEFF Research Database (Denmark)

    Munk, Line; Punt, A. M.; Kabel, M. A.

    2017-01-01

    Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators...... better than HBT (1-hydroxybenzotriazole). Three different mechanisms are suggested to explain the grafting of HPI and HBT, all involving radical-radical coupling to produce covalent bonding to lignin. Lignin from exhaustive cellulase treatment of wheat straw was more susceptible to grafting than beech...... organosolv lignin with the relative abundance of grafting being 35% vs. 11% for HPI and 5% vs. 1% for HBT on these lignin substrates. The data imply that lignin can be functionalized via laccase catalysis with-N-OH type mediators....

  8. Two-photon laser-induced fluorescence studies of HS radicals, DS radicals, and I atoms

    Energy Technology Data Exchange (ETDEWEB)

    Tiee, J J; Ferris, M J; Loge, G W; Wampler, F B

    1983-04-15

    A two-photon laser-induced excitation and fluorescence technique has been used to study the A /sup 2/..sigma../sup +/ - X/sup 2/PI transition of HS and DS radicals and various high-lying /sup 4/P/sup 0/, /sup 2/D/sup 0/, and /sup 4/D/sup 0/ states of the I atom. The two-photon excitation cross sections and detection sensitivity are discussed. 13 references, 5 figures.

  9. ESR study of the anion radicals of 5-nitropyrimidines: conversion to iminoxy radicals

    International Nuclear Information System (INIS)

    Sevilla, M.D.; Clark, C.; Failor, R.

    1976-01-01

    The anion radicals of a number of 5-nitropyrimidines have been investigated by ESR spectroscopy. The anions are formed by electrolysis in dimethylformamide and by electron attachment in aqueous glasses, 12 M LiCl--D 2 O and 8 M NaOD. The electrolysis of 5-nitrouracil and 5-nitro-6-methyluracil results in relatively stable anion radicals. The results for 5-nitrouracil give evidence for two or perhaps three anions which differ only by the degree of ring nitrogen protonation. The results for 5-nitro-6-methyluracil suggest that the nitro group of the anion is twisted so that it is coupled only weakly to the ring π-electron system. The anions of 5-nitrouracil, 5-nitroorotic acid, 5-nitrobarbituric acid, and 5-nitro-6-methyluracil have been produced in the alkaline and neutral aqueous glasses. The anisotropic spectra found have been analyzed with the aid of computer simulations which assume axial symmetry. For example, the analysis of the spectrum of 5-nitrouracil anion in 12 M LiCl yields A/sub parallel//sup N/ = 33; A/sub perpendicular to//sup N/ = 5, a 6 /sup H/ = 5.5 G, g/sub parallel/ = 2.0016, and g/sub perpendicular to/ = 2.0059. A concentration dependence in the splittings is noted and discussed. Ultraviolet photolysis of the anions of 5-nitro-6-methyluracil and 5-nitrobarbituric acid results in the formation of iminoxy radicals. Mechanisms of formation of the iminoxy radicals are discussed and results found in this work are compared to results found in single crystals and aqueous solution

  10. Uma análise behaviorista radical dos sonhos A radical behaviorist analysis of the dreams

    Directory of Open Access Journals (Sweden)

    Francynete Melo e Silva

    2000-01-01

    Full Text Available Embora não haja um consenso acerca de questões sobre o que são os sonhos, porque sonhamos, etc., a maioria dos estudos sobre a natureza dos sonhos concorda que ela está relacionada a condições internas do organismo. Contrariamente, o behaviorismo radical analisa os sonhos como comportamentos privados, sendo produtos das histórias filogenética, ontogenética e cultural. Neste sentido, este trabalho tem como objetivo analisar os sonhos a partir da perspectiva behaviorista radical, considerando-os como comportamentos perceptuais encobertos, argumentando-se que são aprendidos. Afirma-se que a interpretação dos sonhos é impossível se não se conhecem as contingências de reforço com as quais a pessoa está interagindo.In spite of the fact that there is no consensus concerning questions about the nature and origin of dreams, the majority of the studies on the nature of the dreams agrees that they are related to internal conditions of the organism. As opposed to that notion, the radical behaviorism analyses the dreams as private behaviors and, thus, as products of philogenetical, ontogenetical, and cultural histories. In this sense, this paper aims to analyze the dreams from a radical behaviorism perspective, considering them as private events, perceptual behaviors, and arguing that they are learned processes. It is asserted that the dreams interpretation is impossible if the contingencies that control such activity are unknown.

  11. Origin of the Proton-transfer Step in the Cofactor-free (1H)-3-Hydroxy-4-oxoquinaldine 2,4-Dioxygenase

    Science.gov (United States)

    Hernandez-Ortega, Aitor; Quesne, Matthew G.; Bui, Soi; Heuts, Dominic P. H. M.; Steiner, Roberto A.; Heyes, Derren J.; de Visser, Sam P.; Scrutton, Nigel S.

    2014-01-01

    Dioxygenases catalyze a diverse range of chemical reactions that involve the incorporation of oxygen into a substrate and typically use a transition metal or organic cofactor for reaction. Bacterial (1H)-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase (HOD) belongs to a class of oxygenases able to catalyze this energetically unfavorable reaction without any cofactor. In the quinaldine metabolic pathway, HOD breaks down its natural N-heteroaromatic substrate using a mechanism that is still incompletely understood. Experimental and computational approaches were combined to study the initial step of the catalytic cycle. We have investigated the role of the active site His-251/Asp-126 dyad, proposed to be involved in substrate hydroxyl group deprotonation, a critical requirement for subsequent oxygen reaction. The pH profiles obtained under steady-state conditions for the H251A and D126A variants show a strong pH effect on their kcat and kcat/Km constants, with a decrease in kcat/Km of 5500- and 9-fold at pH 10.5, respectively. Substrate deprotonation studies under transient-state conditions show that this step is not rate-limiting and yield a pKa value of ∼7.2 for WT HOD. A large solvent isotope effect was found, and the pKa value was shifted to ∼8.3 in D2O. Crystallographic and computational studies reveal that the mutations have a minor effect on substrate positioning. Computational work shows that both His-251 and Asp-126 are essential for the proton transfer driving force of the initial reaction. This multidisciplinary study offers unambiguous support to the view that substrate deprotonation, driven by the His/Asp dyad, is an essential requirement for its activation. PMID:24482238

  12. Protonation/reduction dynamics at the [4Fe-4S] cluster of the hydrogen-forming cofactor in [FeFe]-hydrogenases.

    Science.gov (United States)

    Senger, Moritz; Mebs, Stefan; Duan, Jifu; Shulenina, Olga; Laun, Konstantin; Kertess, Leonie; Wittkamp, Florian; Apfel, Ulf-Peter; Happe, Thomas; Winkler, Martin; Haumann, Michael; Stripp, Sven T

    2018-01-31

    The [FeFe]-hydrogenases of bacteria and algae are the most efficient hydrogen conversion catalysts in nature. Their active-site cofactor (H-cluster) comprises a [4Fe-4S] cluster linked to a unique diiron site that binds three carbon monoxide (CO) and two cyanide (CN - ) ligands. Understanding microbial hydrogen conversion requires elucidation of the interplay of proton and electron transfer events at the H-cluster. We performed real-time spectroscopy on [FeFe]-hydrogenase protein films under controlled variation of atmospheric gas composition, sample pH, and reductant concentration. Attenuated total reflection Fourier-transform infrared spectroscopy was used to monitor shifts of the CO/CN - vibrational bands in response to redox and protonation changes. Three different [FeFe]-hydrogenases and several protein and cofactor variants were compared, including element and isotopic exchange studies. A protonated equivalent (HoxH) of the oxidized state (Hox) was found, which preferentially accumulated at acidic pH and under reducing conditions. We show that the one-electron reduced state Hred' represents an intrinsically protonated species. Interestingly, the formation of HoxH and Hred' was independent of the established proton pathway to the diiron site. Quantum chemical calculations of the respective CO/CN - infrared band patterns favored a cysteine ligand of the [4Fe-4S] cluster as the protonation site in HoxH and Hred'. We propose that proton-coupled electron transfer facilitates reduction of the [4Fe-4S] cluster and prevents premature formation of a hydride at the catalytic diiron site. Our findings imply that protonation events both at the [4Fe-4S] cluster and at the diiron site of the H-cluster are important in the hydrogen conversion reaction of [FeFe]-hydrogenases.

  13. Prevalence of Anti Human Herpes Virus-6 IgG and its Receptor in Acute Leukemia (Membrane Cofactor Protein: MCP, CD46)

    International Nuclear Information System (INIS)

    Assem, M.M; El-Sharkawy, N.M.; Tarek, H.; Kamel, A.M.; Gad, W.H.; El-Rouby, M.N.; Ghaleb, F.M.

    2005-01-01

    CD46 is a membrane cofactor protein, which acts as a cofactor for factor I proteolytic cleavage of C3, so it protects the cells expressing it on their surface from autologous complement attack. It has been recently described as a receptor for HHV-6. Also, it has been shown to be highly expressed on malignant cells as compared to normal cells, thus playing a major role by which these cells, either cells of haematological malignancy or cells of other body cancers, can protect themselves against complement attack so they can survive and metastasize. Patients and methods: This study has been done to detect the sero prevalence of HHV-6 among 47 Egyptian adult cases of acute leukemia using the anti-HHV-6 IgG ELISA serological technique. CD46 receptor expression and immuno phenotyping technique were performed using FCM. Twenty nine of the cases were ANLL, while 18 were ALL cases. Sixteen age- and sex-matched control cases were also studied for both anti-HHV-6 IgG and CD46 receptor expression. HHV-6 IgG antibodies were encountered in 29 (100%), 14 (77.8%) and 12 (75%) of the ANLL, ALL and the control group, cases, respectively. CD46 expression was encountered in 21 (72.4%) of the ANLL cases and in 10 (55.6%) of the ALL cases. Concordance between HHV6 sero positivity and CD46 expression was encountered in 31 cases (29 positive and 2 negative). Dis concordance was encountered in 16 cases with 14 showing HHV-6 IgG sero positivity with no CD46 expression and 2 showing the reverse. The lack of significant correlation between CD46 expression and sero positivity would exclude CD46 expression as a cause of contracting HHV-6 infection in leukemic patients

  14. Down-regulation of viral replication by adenoviral-mediated expression of siRNA against cellular cofactors for hepatitis C virus

    International Nuclear Information System (INIS)

    Zhang Jing; Yamada, Osamu; Sakamoto, Takashi; Yoshida, Hiroshi; Iwai, Takahiro; Matsushita, Yoshihisa; Shimamura, Hideo; Araki, Hiromasa; Shimotohno, Kunitada

    2004-01-01

    Small interfering RNA (siRNA) is currently being evaluated not only as a powerful tool for functional genomics, but also as a potentially promising therapeutic agent for cancer and infectious diseases. Inhibitory effect of siRNA on viral replication has been demonstrated in multiple pathogenic viruses. However, because of the high sequence specificity of siRNA-mediated RNA degradation, antiviral efficacy of siRNA directed to viral genome will be largely limited by emergence of escape variants resistant to siRNA due to high mutation rates of virus, especially RNA viruses such as poliovirus and hepatitis C virus (HCV). To investigate the therapeutic feasibility of siRNAs specific for the putative cellular cofactors for HCV, we constructed adenovirus vectors expressing siRNAs against La, polypyrimidine tract-binding protein (PTB), subunit gamma of human eukaryotic initiation factors 2B (eIF2Bγ), and human VAMP-associated protein of 33 kDa (hVAP-33). Adenoviral-mediated expression of siRNAs markedly diminished expression of the endogenous genes, and silencing of La, PTB, and hVAP-33 by siRNAs substantially blocked HCV replication in Huh-7 cells. Thus, our studies demonstrate the feasibility and potential of adenoviral-delivered siRNAs specific for cellular cofactors in combating HCV infection, which can be used either alone or in combination with siRNA against viral genome to prevent the escape of mutant variants and provide additive or synergistic anti-HCV effects

  15. Radical versus Social Constructivism: Dilemma, Dialogue, and Defense

    Science.gov (United States)

    Belbase, Shashidhar

    2011-01-01

    This paper aims to discuss epistemological and philosophical foundation of meaningful learning and teaching mathematics and science from the perspective of radical and social constructivism. I have reflected on my experiences of radical and social constructivism through dilemma, dialogue, and defense of my personal epistemology of learning. I went…

  16. Radicals versus Moderates: A Critique of Gyekye's Moderate ...

    African Journals Online (AJOL)

    The communitarian conception of person is a widely accepted view in African thought. Kwame Gyekye thinks there is a distinction between what he calls radical communitarianism and his own version of moderate communitarianism. He is of the view that radical communitarianism is faced with insurmountable problems and ...

  17. Repair Activity of trans-Resveratrol toward 2'-Deoxyguanosine Radicals.

    Science.gov (United States)

    Cheng, Xing; An, Ping; Li, Shujin; Zhou, Liping

    2018-04-26

    In the present study, the repair activity of trans-resveratrol toward 2'-deoxyguanosine (dGuo) radicals in polar and nonpolar solvents was studied using density functional theory. The hydrogen transfer/proton coupled electron transfer and single electron transfer (SET) mechanisms between trans-resveratrol and dGuo-radicals were considered. Taking into consideration the molar fraction of neutral trans-resveratrol (ROH) and anionic trans-resveratrol (RO - ), the overall rate constants for repairing dGuo-radicals by trans-resveratrol are 9.94 × 10 8 and 2.01 × 10 9 dm 3 mol -1 s -1 in polar and nonpolar solvents, respectively, and the overall rate constant of repairing cation radical (dGuo •+ ) by trans-resveratrol via an SET mechanism is 7.17 × 10 9 dm 3 mol -1 s -1 . The repair activity of RO - toward dGuo-radicals is better than that of ROH, but the repair activity of ROH toward dGuo •+ is better than that of RO - . Unfortunately, neither ROH nor RO - can repair the 2'-deoxyribose radicals of dGuo. It can therefore be concluded that trans-resveratrol is an effective antioxidant for repairing base radicals of dGuo and dGuo •+ . The study can help us understand the repair activity of trans-resveratrol toward dGuo radicals.

  18. Free radicals generated by radiolysis of aqueous solutions

    International Nuclear Information System (INIS)

    Schwarz, H.A.

    1981-01-01

    The free radicals produced in the radiolysis of aqueous solutions span the range of redox potentials from -2.9 to +2.65 volts. The identity and nature of these radicals were discussed. Most of the discussion was results obtained with low LET radiation sources ( 60 Co gamma radiation or electron accelerators). Water radiolysis provides the synthesis of many radicals and radical ions in aqueous solution. The primary radicals, e/sub aq/ - H, OH, are well characterized. The radical population can be made to be 90% pure OH (or O - ) if N 2 O solutions are irradiated, the remaining 10% being H atoms. 55% of the radicals can be converted to H atoms in acid solution or in neutral phosphate solutions(e/sub aq/ - reacts with H 2 PO 4- to produce H). The remaining 45% (OH radicals) are difficult to convert to H by reaction with H 2 , due to the slow rate of the reaction. About 100 atmospheres of H 2 are required to do the conversion in less than 10 - 6 sec. 3 figures, 3 tables. (DP)

  19. Teaching Methods in Nutrition: Free Radicals, Antioxidants, and Human Disease.

    Science.gov (United States)

    Janowiak, John J.

    This article presents a teaching methodology for free radical theory and discusses the role of antioxidants in human health. Free radicals are a normal byproduct of respiration, which allows the body to use oxygen, liberate energy, and dispose of harmful substances. The body's antioxidants and nutritional antioxidants quench most of the free…

  20. IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

    Science.gov (United States)

    Schafer, Freya Q.; Yue Qian, Steven; Buettner, Garry R.

    2013-01-01

    Brain tissue being rich in polyunsaturated fatty acids, is very susceptible to lipid peroxidation. Iron is well known to be an important initiator of free radical oxidations. We propose that the principal route to iron-mediated lipid peroxidations is via iron-oxygen complexes rather than the reaction of iron with hydrogen peroxide, the Fenton reaction. To test this hypothesis, we enriched leukemia cells (K-562 and L1210 cells) with docosahexaenoic acid (DHA) as a model for brain tissue, increasing the amount of DHA from approximately 3 mole % to 32 mole %. These cells were then subjected to ferrous iron and dioxygen to initiate lipid peroxidation in the presence or absence of hydrogen peroxide. Lipid-derived radicals were detected using EPR spin trapping with α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN). As expected, lipid-derived radical formation increases with increasing cellular lipid unsaturation. Experiments with Desferal demonstrate that iron is required for the formation of lipid radicals from these cells. Addition of iron to DHA-enriched L1210 cells resulted in significant amounts of radical formation; radical formation increased with increasing amount of iron. However, the exposure of cells to hydrogen peroxide before the addition of ferrous iron did not increase cellular radical formation, but actually decreased spin adduct formation. These data suggest that iron-oxygen complexes are the primary route to the initiation of biological free radical oxidations. This model proposes a mechanism to explain how catalytic iron in brain tissue can be so destructive. PMID:10872752