Phospholipase A2 from the venom of the spider Eresus niger

A phospholipase A₂ with a molecular mass of 12–14 kDa has been isolated from the venom of the spiderEresus niger by three-stage column chromatography. Asparagine has been identified as the N-terminal amino acid.     

Rapid purification of pig heart fumarase by general ligand chromatography

A rapid method for the purification of fumarase from pig heart muscle has been developed using general ligand chromatography with adenosine triphosphate as ligand. Fumarase exhibited distinctive elution patterns from several types of nucleotide-agarose matrices, which may prove of value in distinguishing putative isozymic forms. Fumarase purified from both soluble and particulate fractions of cardiac tissue appeared to be identical in terms of subunit molecular weight, electrophoretic mobility on cellulose acetate, substrate kinetics, and inactivation by several inhibitors. When fresh cardiac tissue was suspended in sucrose medium, both fumarase and citrate synthase were released from the mitochondria to about the same extent (10%). However, fumarase release was increased approximately three-fold, while the release of titrate synthase increased only slightly, when tissue which had been frozen and thawed was suspended in sucrose medium.     

An x-ray structural investigation of cis-matrine — A new stereoisomer of matrine

In an investigation of the three-dimensional structure of the alkaloid matrine by x-ray structural analysis, a new stereoisomer of it has been detected, which has been called cis-matrine. In cis-matrine rings C and D are cis-linked, while the configurations of the A, B, and C fragments in cis-matrine and in ordinary matrine are identical. The cis-matrine molecule is characterized by a greater degree of strain than the molecule by ordinary matrine.     

Isolation and purification of biopolymers by affinity chromatography. VI. Preparation and properties of an affinity adsorbent with a polysaccharide spacer for the purification of proteolytic enzymes

A new affinity sorbent has been synthesized — soybean trypsin inhibitor (STI)-amylopectin-hydrazidosuccinyl-Sepharose — and its properties have been studied in comparison with those of an analogous adsorbent without the spacer STI-Sepharose. The STI-amylopectin-hydrazidosuccinyl-Sepharose adsorbent has been used for the purification of trypsin from porcine pancreas and of callicrein from human blood plasma.     

Heat of reaction and curing of epoxy resin

The heat of reaction and kinetics of curing of diglycidyl ether of bisphenol-A (DGEBA) type of epoxy resin with catalytic amounts of ethylmethylimidazole (EMI) have been studied by differential power-compensated calorimetry as a part of the program for the study of process monitoring for composite materials. The results were compared with those from 1∶1 and 1∶2 molar mixtures of DGEBA and EMI. A method of determination of heat of reaction from dynamic thermoanalytical instruments was given according to basic thermodynamic principles. The complicated mechanism, possibly involving initial ionic formation, has also been observed in other measurements, such as by time-domain dielectric spectroscopy. The behavior of commercially available DGEBA resin versus purified monomeric DGEBA were compared. The melting point of purified monomeric DGEBA crystals is 41.4 °C with a heat of fusion of 81 J/g. The melt of DGEBA is difficult to crystallize upon cooling. The glass transition of purified DGEBA monomer occurs around ?22 °C with aΔC _p of 0.60 J/K/g.     

Relaxation properties and structures of polymer nanocomposites based on modified organoclays

Nanocomposite materials composed of HDPE and new guanidine-containing organoclays have been investigated. The basic changes in the relaxation properties of HDPE after the addition of guanidine-containing organoclays that vary in composition and content have been found. It has been shown that, depending on their structures and affinities for the polymer, guanidine-containing modifiers of montmorillonite have different effects on the structure and relaxation properties of the polymer.     

The Fourier space restricted Hartree-Fock method for the electronic structure calculation of linear poly(tetrafluoroethylene)

Building on the pioneering work of Jean-Marie André and working in the laboratory he founded, the authors have developed a code called FT-1D to make Hartree-Fock electronic structure computations for stereoregular polymers using Ewald-type convergence acceleration methods. That code also takes full advantage of all line-group symmetries to calculate only the minimal set of two-electron integrals and to optimize the computation of the Fock matrix. The present communication reports a benchmark study of the FT-1D code using polytetrafluoroethylene(PTFE) as a test case. Our results not only confirm the algorithmic correctness of the code through agreement with other studies where they are applicable, but also show that the use of convergence acceleration enables accurate results to be obtained in situations where other widely-used codes(e.g., PLH and Crystal) fail. It is also found that full attention to the line-group symmetry of the PTFE polymer leads to an increase of between one and two orders of magnitude in the speed of computation. The new code can therefore be viewed as extending the range of electronic-structure computations for stereoregular polymers beyond the present scope of the successful and valuable code Crystal.     

Influence of chemical nature of aerosilogel surface on proton conductivity of the Nafion-containing composites

Aerosilogel modified with hydroxylaluminum (=Al-OH) groups has been synthesized via the molecular layering procedure, and aerosilogel modified with aminopropylsilyl groups [≡Si(CH₂)₃NH₂] has been prepared via chemisorption of (3-aminopropyl)triethoxysilane. The modified aerosilogel have been further used to prepare composite Nafion-containing electrolytes Nafion. Electrical conductivity of the produced materials has been studied by impedance spectroscopy. Chemical modification of the gel surface strongly affects proton conductivity of Nafion-containing composites.     

Phosphatase activities of fractions of the venom of Renard's viperVipera ursini renardi

The separation of the venom of Renard's viper by filtration through Sephadex G-75 gel has been performed and phosphatase activities have been determined in the fractions and in the course of separation. The bulk of the activity of the phosphatases investigated was concentrated in the high-molecular-weight fractions I and II. A correlation has been found in the distribution of the DNase and ATP-pyrophosphatase activities with the phosphodiesterase activity in the venom fractions. There is no correlation in the distribution of the RNase and phosphodiesterase activity.     

Study of gamma radiation induced damages and variation of oxygen enhancement ratio with radiation dose using Saccharomyces cerevisiae

In the present study, an attempt has been made to quantify Oxygen Enhancement Ratio (OER) and variation of OER as a function of dose with experimental and theoretical formulations using Saccharomyces cerevisiae D7, X2180 and rad 52. The study confirms that, the variation of OER with dose depends upon type of cell and repair proficiency of cells. A theoretical model has been formulated to estimate OER values. With the help of this model, OER value for any dose can be calculated in the exponential region of the survival curve without actually extending the experiment in that dose region.     

Kinetics and possible mechanism of hydrogen chloride oxidation over supported copper-containing salt catalysts: I. Kinetics of HCl oxidation in the deacon and methane oxychlorination reactions over a copper-potassium salt catalyst

The kinetics of HCl oxidation at 350–425°C over a (CuCl₂-KCl)/support catalyst in two complementary processes—Deacon and methane oxychlorination reactions—has been investigated using a gradientless technique. This has allowed the range of \(P_{Cl_2 }\) in the reaction mixture to be markedly extended. New kinetic features of HCl oxidation under conditions such that this process does and does not depend on P _HCl have been discovered. The kinetic equations obtained in this study fit experimental data in a wider range of conditions than the equations proposed earlier. The results of this study suggest the existence of two HCl oxidation pathways in the Deacon reaction.     

Synthesis,structures, characterization and antimicrobial activity of two novel coordination complexes derived from 2-naphthoxyacetic acid

Two novel coordination complexes, namely, [Cd(2-NOA)₂(TBZ)₂] (1) and [Mn(2-NOA)₂(H₂O)₂]_n (2) (2-NOAH = 2-naphthoxyacetic acid), have been hydrothermally synthesized through the reaction of 2-naphthoxyacetic acid with or without N-donor ancillary coligand (thiabendazole, TBZ) in the presence of divalent transition-metal salts. Complex 1 is a zero-dimensional (0D) molecule, and the self-complementary C–H···O hydrogen bonds extend these molecules into a 2D supramolecular framework. In polymer 2, 2-NOA ^? acts as a bridging ligand to bind Mn(II) ions to form a 2D supermolecular assembly. Also, IR spectra, powder X-ray diffraction, fluorescence properties and thermal decomposition process of complexes were investigated. The effect of the TBZ base ligand and the complex 1 on the antimicrobial activity against Candida albicans was studied.     

Simultaneous determination of bufadienolides and phenolic compounds in sea squill (Drimia maritima (L.) Stearn) by HPLC-DAD-MSn as a means to differentiate individual plant parts and developmental stages

Mediterranean sea squill (Drimia maritima (L.) Stearn) is used in the production of medicinal products. Current HPLC methods comprise tedious sample clean-up and have been merely focused on the analysis of cardiac glycosides, whereas a thorough characterization of D. maritima considering both the latter compound class and more hydrophilic secondary metabolites in one HPLC run has not been performed so far. Consequently, a novel HPLC-DAD-MSⁿ method has been developed allowing the simultaneous determination of both cardiac glycosides and phenolic compounds, which is characterized by simplified sample preparation. This method was applied to characterize sea squill, revealing a complex profile of its extractive compounds derived from the two classes. Furthermore, the potential of the method reported here to quantitate the predominant compounds, i.e., dihydroquercetin derivatives and bufadienolides, was demonstrated. The occurrence of phenolic compounds, not described for sea squill so far, and of characteristic compounds specific to individual plant parts or vegetation stages was further addressed. The data revealed that classification of various vegetation phases based on quantitative evaluation of bufadienolides and dihydroquercetin derivatives applying principal component analysis (PCA) appears possible. Thus, the methodology presented here forms the basis for future routine application in quality control of raw materials and pharmaceutical preparations derived from sea squill. This will allow systematic comparison of different plant parts, vegetation stages and origins based on an extended sample set. Figure

Red sea squill with inflorescence and cross-section of a fresh bulb     

Kinetics and possible mechanism of hydrogen chloride oxidation over supported copper-containing salt catalysts: II. Kinetics of HCl oxidation in the deacon and methane oxychlorination reactions over the CuCl2-KCl-LaCl3 catalyst

The kinetics of HCl oxidation at 350–425°C over the supported CuCl₂-KCl-LaCl₃ catalyst has been investigated using a gradientless technique. The HCl oxidation kinetics in the Deacon and methane oxychlorination reactions has been studied in order to substantially extend the \(Cl_2 \left( {P_{Cl_2 } } \right)\) partial pressure variation range. When the reaction rate is independent of P _HCl, HCl oxidation on the copper-potassium catalysts is described by the same rate equation, irrespective of whether the catalyst contains lanthanum or not. The introduction of lanthanum chloride increases the HCl oxidation rate by one order of magnitude. The rate equation obtained has significant advantages over the equation corresponding to the Kenney-Slama equation. The kinetic features of HCl oxidation over the lanthanum-containing catalyst, whether the process depends on P _HCl or not, can be explained in terms of the superposition of the Kenney-Slama dissociative mechanism and the catalytic mechanism suggested here. The role of lanthanum chloride in both HCl oxidation pathways is considered.     

Ultrasensitive detection and identification of BRAF V600 mutations in fresh frozen,FFPE, and plasma samples of melanoma patients by E-ice-COLD-PCR

A number of molecular diagnostic methods have been developed for the detection and identification of mutations in tumor samples, which are important for the choice of treatment in the context of personalized medicine. For the treatment of metastatic melanoma, Vemurafenib is recommended for patients with BRAF V600 activating mutations. However, the different assays developed to date for the detection of these mutations lack sensitivity or specificity or do not allow a sequencing-based identification or validation of the mutation. Recently, enhanced improved and complete enrichment co-amplification at lower denaturation temperature-polymerase chain reaction (E-ice-COLD-PCR) has been developed as a sensitive method for the detection and identification of mutations in KRAS codons 12/13. Here, we present the first E-ice-COLD-PCR assay for the detection and identification of BRAF codon 600 mutations, which has a large dynamic range, as 25 pg to 25 ng can be used as DNA input without any reduction in mutation enrichment efficiency, and which can detect down to 0.01 % of mutated alleles in a wild-type background. The assay has been validated on fresh frozen, formalin-fixed paraffin-embedded (FFPE), and plasma samples of melanoma patients and has allowed the detection and identification of BRAF mutations present in samples appearing as wild type using standard pyrosequencing, endpoint genotyping, or Sanger sequencing. Thus, the BRAF V600 E-ice-COLD-PCR assay is currently one of the most powerful molecular diagnostic tools for the ultrasensitive detection and identification of BRAF codon 600 mutations.     

Chemical modification of heptaene macrolide antibiotic Amphotericin B under conditions of the Atherton-Todd reaction

Chemical modification of heptaene macrolide antibiotic Amphotericin B with dialkyl(diaryl)-phosphites has been performed under conditions of the Atherton-Todd reaction. As a result, the corresponding dialkyl(aryl)amidophosphonate derivatives of Amphotericin B have been formed. The prepared derivatives have been characterized by their physicochemical properties, toxicity, and antifungal activity against a set of test cultures of pathogenic fungi and yeast-like fungi of the Candida species.     

In Situ Characterization of Proteins Using Laserspray Ionization on a High-Performance MALDI-LTQ-Orbitrap Mass Spectrometer

The MALDI-LTQ-Orbitrap XL mass spectrometer is a high performance instrument capable of high resolution and accurate mass (HRAM) measurements. The maximum m/z of 4000 precludes the MALDI analysis of proteins without generating multiply charged ions. Herein, we present the study of HRAM laserspray ionization mass spectrometry (MS) with MS/MS and MS imaging capabilities using 2-nitrophloroglucinol (2-NPG) as matrix on a MALDI-LTQ-Orbitrap XL mass spectrometer. The optimized conditions for multiply charged ion production have been determined and applied to tissue profiling and imaging. Biomolecules as large as 15 kDa have been detected with up to five positive charges at 100 K mass resolution (at m/z 400). More importantly, MS/MS and protein identification on multiply charged precursor ions from both standards and tissue samples have been achieved for the first time with an intermediate-pressure source. The initial results reported in this study highlight potential utilities of laserspray ionization MS analysis for simultaneous in situ protein identification, visualization, and characterization from complex tissue samples on a commercially available HRAM MALDI MS system. Graphical Abstract

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Phytochemicals as Inhibitors of Bacterial Cell Division Protein FtsZ: Coumarins Are Promising Candidates

Naturally occurring phytochemicals with reported antibacterial activity were screened for their ability to inhibit the bacterial cell division protein Escherichia coli FtsZ. Among the representative compounds, coumarins inhibit the GTPase and polymerization activities of this protein effectively. Further screening with ten coumarin analogs we identified two promising candidates, scopoletin and daphnetin. The former is found to inhibit the GTPase activity of the protein in a noncompetitive manner. Docking of these coumarins with the modeled protein indicate that they bind to T7 loop, which is different from the GTP-binding site (active site), thereby supporting the experimental data. Lowest binding energy is obtained with scopoletin. 3D QSAR indicates the need for groups such as hydroxyl, diethyl, or dimethyl amino in the 7th carbon for enhanced activity. None of the coumarins exhibited cytotoxicity against NIH/3T3 and human embryonic kidney cell lines. The length of Bacillus subtilis increases in the presence of these compounds probably due to the lack of septum formation. Results of this study indicate the role of coumarins in halting the first step of bacterial cell division process.     

Electron spin resonance study of the photoreaction of 2,2’,3,3’,5,5’,6,6’-octaphenyl-4, 4’-bi-4h-pyran in tetrahydrofuran

Photodissociation of 2,2’,3,3’,5,5’,6,6’-octaphenyl-4,4’-bi-4H-pyran (D) and recombination of 2,3,5,6-tetraphenylpyranyl radical in tetrahydrofuran solution were investigated by ESR methods. The pattern of the CIDEP signal of the radical indicaess that the photodissociation occurs from the excited singlet state of D. The activatinn energy of the radical recombination was obtained to be 16 ~ 18 kJ/mol. By lowering the temperature of photorrradiatton to -140° C, a radical pair was found to be trapped in the medium and its zero field splitting parameters were determined as | D | = 0.0119 cm^-1 and | E | = 0.00050 cm^-1.     

Structural characterization and electrical conductivity studies of BaMoO4 nanofibers prepared by sol–gel and electrospinning techniques

Scheelite type BaMoO₄ nanofibers were prepared by using acrylamide assisted sol–gel process and electrospinning technique. The prepared Scheelite BaMoO₄ nanofibers were characterized by using TG/DTA, XRD, FTIR, FT-Raman and SEM–EDX techniques. Thermal behavior, crystalline phase and structure of the prepared BaMoO₄ nanofibers samples were confirmed from the analysis of the obtained results of TG/DTA, XRD, FTIR and FT-Raman respectively. SEM micrographs along with EDX showed the formation of one dimensional (1D) nanofibers 100–350 nm diameters and existence of Ba, Mo and O elements in the BaMoO₄ nanofibers sample. The electrical conductivity of BaMoO₄ nanofibers as a function of temperature 200–400 °C under air was evaluated by analyzing the measured impedance data using the winfit software. The newly prepared Scheelite type BaMoO₄ nanofibers showed electrical conductivity of 0.92 × 10^?3 S/cm at 400 °C.