407 research outputs found

    Biocatalytic synthesis of flavones and hydroxyl-small molecules by recombinant Escherichia coli cells expressing the cyanobacterial CYP110E1 gene

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    Background: Cyanobacteria possess several cytochrome P450s, but very little is known about their catalytic functions. CYP110 genes unique to cyanaobacteria are widely distributed in heterocyst-forming cyanobacteria including nitrogen-fixing genera Nostoc and Anabaena. We screened the biocatalytic functions of all P450s from three cyanobacterial strains of genus Nostoc or Anabaena using a series of small molecules that contain flavonoids, sesquiterpenes, low-molecular-weight drugs, and other aromatic compounds. Results: Escherichia coli cells carrying each P450 gene that was inserted into the pRED vector, containing the RhFRed reductase domain sequence from Rhodococcus sp. NCIMB 9784 P450RhF (CYP116B2), were co-cultured with substrates and products were identified when bioconversion reactions proceeded. Consequently, CYP110E1 of Nostoc sp. strain PCC 7120, located in close proximity to the first branch point in the phylogenetic tree of the CYP110 family, was found to be promiscuous for the substrate range mediating the biotransformation of various small molecules. Naringenin and (hydroxyl) flavanones were respectively converted to apigenin and (hydroxyl) flavones, by functioning as a flavone synthase. Such an activity is reported for the first time in prokaryotic P450s. Additionally, CYP110E1 biotransformed the notable sesquiterpene zerumbone, anti-inflammatory drugs ibuprofen and flurbiprofen (methylester forms), and some aryl compounds such as 1-methoxy and 1-ethoxy naphthalene to produce hydroxylated compounds that are difficult to synthesize chemically, including novel compounds. Conclusion: We elucidated that the CYP110E1 gene, C-terminally fused to the P450RhF RhFRed reductase domain sequence, is functionally expressed in E. coli to synthesize a robust monooxygenase, which shows promiscuous substrate specificity (affinity) for various small molecules, allowing the biosynthesis of not only flavones (from flavanones) but also a variety of hydroxyl-small molecules that may span pharmaceutical and nutraceutical industries

    Preparation of Ionic Liquids Containing Siloxane Frameworks

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    This chapter deals with our recent researches on the preparation and properties of thermally stable ionic liquids (ILs) containing siloxane frameworks. ILs containing randomly structured oligosilsesquioxanes with quaternary ammonium side-chain groups (Am-Random-SQ-IL) and with imidazolium side-chain groups (Im-Random-SQ-IL) were successfully prepared by the hydrolytic condensation of the corresponding trifunctional alkoxysilanes in aqueous bis(trifluoromethanesulfonyl)imide (HNTf2) solution. It is also reported that ILs containing cage-like oligosilsesquioxanes (POSSs) with imidazolium side-chain groups (Im-Cage-SQ-IL) and with random distribution of quaternary ammonium and imidazolium side-chain groups (Amim-Cage-SQ-IL)were obtained, when the similar hydrolytic condensations were performed in a water/methanol (1 : 19 v/v) mixed solution of HNTf2. In addition, we investigated the preparation of ILs containing cyclic oligosiloxanes with various imidazolium side-chain groups (MeIm-CyS-IL-NTf2, MeIm-CyS-IL-OTf, HIm-CyS-IL-NTf2, EtIm-CyS-IL-NTf2, PrIm-CyS-IL-NTf2, and BuIm-CyS-IL-NTf2) by the hydrolytic condensation of the corresponding difunctional alkoxysilanes in the solutions of superacids, such as HNTf2 and trifluoromethanesulfonic acid (HOTf)

    Hairy black holes in AdS with Robin boundary conditions

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    We study hairy black holes in Einstein-Maxwell-complex scalar theory in four-dimensional asymptotically global anti-de Sitter (AdS) spacetime when the Robin boundary conditions are imposed on the scalar field. This setup is dual to the double trace deformation of strongly interacting field theory on R×S2R \times S^2 by charged scalar operators. We identify the instability of the Reissner-Nordstr\"{o}m-AdS (RNAdS) black holes under the Robin boundary conditions and construct backreacted geometries branching at the onset of the instability. Also considering associated horizonless geometries called boson stars, we obtain phase diagrams with fairly rich structure in the grand canonical ensemble depending on the boundary condition parameter or the deformation parameter, where phase transition occurs between thermal AdS, RNAdS, charged boson stars, and hairy black holes.Comment: 30 pages, 10 figure

    Parity doublet model for baryon octets: diquark classifications and mass hierarchy based on the quark-line diagram

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    We construct SU(3)LSU(3)R {\rm SU(3)}_{\rm L} \otimes {\rm SU(3)}_{\rm R} invariant parity doublet models within the linear realization of the chiral symmetry. Describing baryons as the superposition of linear representations should be useful description for transitions toward the chiral restoration. The major problem in the construction is that there are much more chiral representations for baryons than in the two-flavor cases. To reduce the number of possible baryon fields, we introduce a hierarchy between representations with good or bad diquarks (called soft and hard baryon representations, respectively). We use (3,3ˉ)+(3ˉ,3)(3,\bar3)+(\bar3,3) and (8,1)+(1,8)(8,1)+(1,8) as soft to construct a chiral invariant Lagrangian, while the (3,6)+(6,3)(3,6)+(6,3) representations are assumed to be integrated out, leaving some effective interactions. The mass splitting associated with the strange quark mass is analyzed in the first and second order in the meson fields MM in (3,3ˉ)+(3ˉ,3)(3,\bar3)+(\bar3,3) representations. We found that the chiral SU(3)LSU(3)R {\rm SU(3)}_L \otimes {\rm SU(3)}_R constraints are far more restrictive than the SU(3)V {\rm SU(3)}_V constraints used in conventional models for baryons. After extensive analyses within (3,3ˉ)+(3ˉ,3)(3,\bar3)+(\bar3,3) and (8,1)+(1,8)(8,1)+(1,8) models, we found that models in the first order of MM do not reproduce the mass hierarchy correctly, although the {\GO} is satisfied. In the second order, the masses of the positive parity channels are reproduced well up to the first radial excitations, while some problem in the mass ordering remains in a negative parity channel. Apparently the baryon dynamics is not well-saturated by just (3,3ˉ)+(3ˉ,3)(3,\bar3)+(\bar3,3) and (8,1)+(1,8)(8,1)+(1,8) representations, as indicated by the necessity of terms higher order in MM

    What a Load of Rubbish: Japan’s Problem with Increasing Disposable Container and Packaging Waste

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    Huge amounts of plastic are used in everyday life. However, much of the plastic used for disposable containers and packaging is used once and then discarded. This can then cause a serious environmental problem. After describing the environmental effects and possible ways of treatment, this paper examines the situation in Japan, particularly with respect to how reuse and waste reduction can be achieved in Japan by adopting better extended producer responsibility schemes, introducing bans or fees for shopping bags etc. The specifi c roles that governments, companies and individual people can play are discussed in detail, and a comparison is made with some of the methods that have been adopted in other countries and which may be applicable to Japan

    Search for Tetraneutron by Pion Double Charge Exchange Reaction at J-PARC

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    Tetraneutron (4n^4n) has come back in the limelight, because of recent observation of a candidate resonant state at RIBF. We propose to investigate the pion double charge exchange (DCX) reaction, i.e. 4He(π,π+)^4\mathrm{He}({\pi}^- , {\pi}^+), as an alternative way to populate tetraneutron. An intense π{\pi}^- beam with the kinetic energy of ~850 MeV, much higher than that in past experiments at LAMPF and TRIUMF, will open up a possibility to improve the experimental sensitivity of the formation cross section, which will be much smaller than hitherto known DCX cross sections such as 9Be(π,π+)9He (g.s.)^9\mathrm{Be}({\pi}^-, {\pi}^+)^9\mathrm{He}\ (g.s.).Comment: 4 pages, 1 figure; proceedings of the 14th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2016), Kyoto, Japan, 25-30 July 201
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