407 research outputs found
Biocatalytic synthesis of flavones and hydroxyl-small molecules by recombinant Escherichia coli cells expressing the cyanobacterial CYP110E1 gene
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
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
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 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
We construct 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 and as soft to construct a chiral
invariant Lagrangian, while the 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 in representations. We
found that the chiral constraints are
far more restrictive than the constraints used in conventional
models for baryons. After extensive analyses within and
models, we found that models in the first order of 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 and representations,
as indicated by the necessity of terms higher order in
What a Load of Rubbish: Japan’s Problem with Increasing Disposable Container and Packaging Waste
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
Tetraneutron () 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. , as an alternative way to populate tetraneutron. An intense
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 .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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