Purification and Characterization of a Naringinase from <Emphasis Type="Italic">Cryptococcus albidus</Emphasis>

Naringinase which was extracted from the fermented broth of Cryptococcus albidus was purified about 42-folds with yield 0.7% by sulfate fractionation and chromatography on Toyopearl HW-60, Fractogel DEAE-650-s, and Sepharose 6B columns. Molecular weight of protein determined by gel filtration and SDS-PAGE was 50 kDa. Naringinase of C. albidus includes high content of the dicarbonic and hydrophobic amino acids. Enzyme contains also carbohydrate component, represented by mannose, galactose, rhamnose, ribose, arabinose, xylose, and glucose. The enzyme was optimally active at pH 5.0 and 60 °C. Naringinase was found to exhibit specificity towards p-nitrophenyl-α-L-rhamnose, p-nitrophenyl-β-D-glucose, naringin, and neohesperidin. Its K _m towards naringin was 0.77 mM and the V _max was 36 U/mg. Naringinase was inhibited by high concentrations of reaction product—L-rhamnose. Enzyme revealed stability to 20% ethanol and 500 mM glucose in the reaction mixture that makes it possible to forecast its practical use in the food industry in the production of juices and wines.     

Synthesis,Crystal Structure and Hirshfeld Surfaces of the N-(bis(benzylamino)phosphoryl)-4-Methylbenzenesulfonamide Polymeric tetrakis-Complex {Na[Yb(L)4(iPrOH)]}n

Lanthanide containing polymer chain of title compound {Na[Yb(L)₄(ⁱPrOH)]}_n is formed by alternating complex anions and sodium cations. The anion is composed by four deprotonated bidentate chelate ligands of sulfonylamidophosphate type N-(bis(benzylamino)phosphoryl)-4-methylbenzenesulfonamide (L^?) coordinated to the Yb(III) ion via O atoms belonging to the sulfonyl and phosphoryl groups. The coordination polyhedron of the ytterbium has a slightly distorted triangular dodecahedron conformation, TDD-8, D_2d. The Na⁺ cation is coordinated by four sulfonyl O atoms, the NaO₄ polyhedra shape is intermediate between axially vacant trigonal bipyramid C_3v and tetrahedron T_d. Single-crystal X-ray diffraction studies show that one 2-propanol molecule is hydrogen-bonded to the sulphonyl oxygen of one of the chelate ligands. Also the extensive network of hydrogen bonding interactions between the aromatic rings both in the structural unit and between the polymer chains were detected. They were investigated by the analysis of Hirshfeld surfaces and fingerprint plots. The correlations between structure parameters obtained and the physico-chemical properties of the {Na[Yb(L)₄(ⁱPrOH)]}_n were investigated.

Graphic Abstract

New tetrakis-complex {Na[Yb(L)₄(ⁱPrOH)]}_n was synthesized and characterized by X-ray crystallography. Structural packaging characteristics were investigated by the analysis of Hirshfeld surfaces.

     

Corrole and Porphyrin Amino Acid Conjugates: Synthesis and Physicochemical Properties

A series of conjugates of amino acids with porphyrins and corroles was synthesized. Their self‐assembling ability under defined conditions was investigated by scanning electron microscopy. The morphology and photophysical properties of these molecules were studied by absorption and fluorescence spectroscopy in solid, liquid, and self‐assembled forms. We observed that both corrole and porphyrin conjugated with the l ‐phenylalanine–l ‐phenylalanine peptide to form spherical nanostructures with bathochromic shifts in the emission spectra, indicating the formation of aggregates. These aggregates are characterized by the impressive absorption of light over nearly the whole visible range. The broadening of all bands was particularly strong in the case of corroles. The fluorescence lifetimes of self‐assembled species were longer as compared to the solid‐state form.     

Synthesis of Triptycene‐Substituted Azapentacene and Azahexacene Derivatives

We describe the synthesis and characterization of novel iptycene‐substituted azaacenes by using either a classic condensation route (diamine plus ortho‐quinone) and/or a Pd‐catalyzed coupling of an aromatic diamine with an aromatic dihalide. The attachment of an iptycene unit leads to a significant blueshift (15 nm) in the UV/Vis spectra of these azaacenes. The iptycene unit stabilizes a hexaazahexacene with a λ_{max abs} of 833 nm. By employing 5,6‐diamino(benzothiadiazole) as a synthon for tetraaminobenzene, we could prepare the symmetrical bis‐triptycene‐substituted tetraazapentacene in high yields.     

Meta-substituted Ru rigid rods for sensitization of TiO2

Ruthenium polypyridyl rigid-rod compounds with phenylene–ethynelene (OPE) spacers and an isophthalic acid (Ipa) binding group were synthesized and characterized for sensitization of nanocrystalline TiO₂ (anatase) thin films. Density functional theory predicted that the most stable structure oriented the isophthalic group about 45° from normal to the TiO₂ surface. Comparative experimental studies of meta- and para-isomers revealed small changes in the ground state absorption spectra and very similar excited state and redox properties. The excited state injection yields (inj = 0.15 ± 0.03) into nanocrystalline TiO₂ and the subsequent charge recombination rates were found to be insensitive to the isomer utilized. Meta-substitution enabled the synthesis of sensitizers with two Ru^II sensitizers that displayed enhanced sunlight absorption relative to the monomeric compound.     

Surface analysis of bacterial systems using cryo-X-ray photoelectron spectroscopy

Surface analysis of biological systems using XPS often requires dehydration of the sample for it to be compatible with the ultrahigh vacuum of the spectrometer. However, if samples are frozen to liquid-nitrogen temperature prior to and during analysis, water can be retained in the sample and the organization of the sample surface should be preserved to a higher degree than in desiccated samples. This article presents recent developments of cryo-X-ray photoelectron spectroscopy (cryo-XPS) for analyses of hydrated biological samples at liquid nitrogen temperature. We describe experiments on bacterial cells, bacterial biofilms, and bacterial outer membrane vesicles using a variety of bacterial species. Differences and similarities in surface chemistry are monitored depending on growth in liquid culture, on culture plates, as well as in biofilms, and are discussed. Two data treatment methods providing decomposition of the C 1s spectra into lipid, polysaccharide, and peptide/peptidoglycan content are used and compared.     

Synchronization phenomena in the system consisting of m coupled Berger plates

The dynamical system arising in the study of nonlinear oscillations of a number of coupled Berger plates is considered. The dependence of the long-time behavior of the trajectories of the system on the properties of the coupling operator is studied. It is shown that the global attractor of the dynamical system is continuous with respect to the coupling parameter γ expressing the intensity of plate interaction. When γ→∞ it converges upper semicontinuously to the attractor of the system generated by the projection of the vector field of the coupled system on the kernel of the coupling operator. For the particular case of 3-diagonal coupling operator the synchronization phenomenon at the level of attractors is stated for large values of γ as well as the absence of synchronization for γ small. The case of cluster synchronization is also considered.     

The CYPome of Sorangium cellulosum So ce56 and identification of CYP109D1 as a new fatty acid hydroxylase

The first systematic study of the complete cytochrome P450 complement (CYPome) of Sorangium cellulosum So ce56, which is a producer of important secondary metabolites and has the largest bacterial?genome sequenced to date, is presented. We describe the bioinformatic analysis of the So ce56 cytochrome P450 complement consisting of 21 putative P450 genes. Because fatty acids play a pivotal role during the complex life cycle of myxobacteria, we focused our studies on the characterization of fatty acid hydroxylases. Three novel potential fatty acid hydroxylases (CYP109D1, CYP264A1, and CYP266A1) were used for detailed characterization. One of them, CYP109D1 was able to perform subterminal hydroxylation of saturated fatty acids with the support of two autologous and one heterologous electron transfer system(s). The kinetic parameters for the product hydroxylation were derived.     

A mixed integer programming model for long term capacity expansion planning: A case study from The Hunter Valley Coal Chain

The Hunter Valley Coal Chain is the largest coal export operation in the world with a throughput in excess of 100 million tonnes per annum (Mtpa). Coal is delivered to the shipping terminal from 40 mines using 27 coal load points spread across the Hunter Valley region. This paper describes an MILP model for determining the capacity requirements, and the most cost effective capacity improvement initiatives, to meet demand while minimising the total cost of infrastructure and demurrage. We present results from computational experiments on the model’s performance along with a comparison of the model’s output with detailed analyses by the coal chain analysts and planners.     

Comment on: “Some exact solutions of KdV equation with variable coefficients” [Commun Nonlinear Sci Numer Simul 2011;16:1783–86]

It is shown that in the commented paper the exact solutions were found only for those variable-coefficient KdV equations which are reduced to the classical (constant-coefficient) KdV equation by point transformations, and these solutions are preimages of well-known traveling wave solutions of the KdV equation with respect to the corresponding point transformations. The equivalence-based approach suggested in [Popovych RO, Vaneeva OO. More common errors in finding exact solutions of nonlinear differential equations: Part I. Commun Nonlinear Sci Numer Simul 2010;15:3887–99] allows one to obtain more results. This disproves the relevance of the extended mapping transformation method for the class of equations under consideration.