Anomalous behavior of radioiodine: Solvent extraction from acidic solution

Anomalous behavior of radioiodine was found in solvent extraction. Iodine was extracted into CS₂ from acidic solution over a wide range of iodine concentration. The distribution ratio was obtained by measuring the -rays from iodine-131. The ratio drastically changed at about 10^–5 mol l^–1. The change is readily explained by the kinetic behavior of radioiodine.     

One pot synthesis of the dinucleoside phosphonate GpCH2U

Summary The preparation of the dinucleoside phosphonate GpCH₂U, starting from the isosteric phosphonate analogue of uridine (3) and the guanosine derivative5 is described.

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Eintopfsynthese des Dinucleosidphosphonats GpCH₂U

Zusammenfassung Die Herstellung des Dinucleosidphosphonats GpCH₂U aus dem isosteren Phosphonatanalogen von Uridin (3) und dem Guanosinderivat5 wird beschrieben.

     

Simultaneous electrophoretic analysis of proteins of very high and low molecular weights using low-percentage acrylamide gel and a gradient SDS-PAGE gel

To be able to separate and analyze giant proteins and small proteins in the same electrophoretic gel, we have used a continuous SDS-PAGE gel formed by the combination of a low-percentage acrylamide gel and a gradient SDS-PAGE gel that we have named LAG gel. To get a good resolution for proteins of more than 200 kDa, we used an acrylamide/bisacrylamide ratio of 80:1 in the low-percentage acrylamide gel. To successfully resolve proteins in the 5-200 kDa range, we used a conventional 6-15% SDS-PAGE gradient gel with the standard acrylamide/bisacrylamide ratio of 40:1. We show that the LAG system can be successfully used in general applications of SDS-PAGE electrophoresis such as proteomics and immunobloting techniques. Thus, using this continuous LAG gel, it is possible to simultaneously analyze giant proteins, such as HERC1 and dynein, big proteins like clathrin heavy chain and small proteins like ARF. The LAG system has a good resolution, low cost, and high reproducibility. Moreover, to simultaneously analyze all proteins saves time. All these characteristics, together with the use of a standard apparatus found in any biochemistry laboratory, make the LAG system an easy tool to use.     

Anomalous magnetic behavior in the transition metal ions doped Cu2O flower-like nanostructures

Cuprous oxide (Cu₂O) flower-like nanostructures doped with various metal ions i.e. Fe, Co, Ni and Mn have been synthesized by an organic phase solution method. The powder X-ray diffraction study clearly reveals them as single phase simple cubic cuprite lattice. Study of their magnetic properties have shown that these doped samples are ferromagnetic in nature; however, no such property was observed for the undoped Cu₂O sample. The magnitude of the ferromagnetic behavior was found to be dependent on the dopant metal ions amount, which increased consistently with its increase. As total magnetic moment contribution of the doped metal ions calculated was insignificant, it is believed to have originated from the induced magnetic moments at cation deficiency sites in the material, created possibly due to the disturbance of the crystal lattice by the dopant ions. The existence of the defects has been supported by photoluminescence spectra of the doped samples.     

Anomalous electrophoretic behavior of a chitinase isoform from grape berries and wine in glycol chitin-containing sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels

An anomalous electrophoretic behavior of a chitinase isoform present in both grape (Vitis vinifera L.) berries and wine was observed in glycol chitin-containing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gels. A progressive shift of the relative molecular mass M(r) of the enzyme (from approximately 30,500 up to approximately 57,700) with increasing glycol chitin concentration in the gels up to 0.1% was revealed when samples were electrophoresed under nonreducing conditions, whereas the presence of glycol chitin had no effects when samples were reduced before SDS-PAGE separation. The M(r) of other grape and wine chitinase isoforms as well as that of the chitinase from pomegranate (Punica granatum L.) fruit was unaffected by the presence of the substrate in the gel under both reducing and nonreducing conditions. Since the enzymes were inactive during the electrophoretic separation, it is likely that the retarding effect of glycol chitin observed specifically for the unreduced chitinase band from grape and wine was due to an interaction between the substrate and a chitin-binding domain different from the catalytic site, such as that typical of class I and class IV chitinases.     

Anomalous electrophoretic mobility of microgel particles in buffer solutions

The electrophoretic mobility (μ) of tunable surface charge poly(N-isopropylacrylamide) microgel particles (PNIPAM) was measured vs pH, using different anionic buffers. Two minima, just at the buffers’ pK values, were found for the μ-pH curve. The preferential penetration of the small counterions into the soft-charged shell explains the electrokinetic charge reduction. For pH values higher than the pK, the charge screening leads to electrostatic repulsions among coions. It pushes them towards the particles; thus, balancing the global ionic distribution.     

Adaptive contrast enhancement of two-dimensional electrophoretic protein gel images facilitates visualization, orientation and alignment

2-DE is a powerful technique to discriminate post-translationally modified protein isoforms. However, all steps of 2-DE preparation and gel-staining may introduce unwanted artefacts, including inconsistent variation of background intensity over the entire 2-DE gel image. Background intensity variations limit the accuracy of gel orientation, overlay alignment and spot detection methods. We present a compact and efficient denoising algorithm that adaptively enhances the image contrast and then, through thresholding and median filtering, removes the gray-scale range covering the background. Applicability of the algorithm is demonstrated on immunoblots, isotope-labeled gels, and protein-stained gels. Validation is performed in contexts of (i) automatic gel orientation based on Hough transformation, (ii) overlay alignment based on cross correlation and (iii) spot detection. In gel stains with low background variability, e.g. Sypro Ruby, denoising will lower the spot detection sensitivity. In gel regions with high background levels denoising enhances spot detection. We propose that the denoising algorithm prepares images with high background for further automatic analysis, without requiring manual input on a gel-to-gel basis.     

Cyclen based lanthanide ion ribonuclease mimics: the effect of pyridine cofactors upon phosphodiester HPNP hydrolysis

The cyclen based pyridine complexes 1Ln-3Ln (Ln = La(III) and Eu(III)) were synthesised as metallo-ribonuclease mimics and their ability to hydrolytically cleave the phosphodiester of HPNP at 37 °C was investigated using UV-vis spectroscopy, whereas the binding of the substrate was evaluated using ³¹P NMR and Eu(III)-luminescent measurements. In contrast 2La gave rise to fast pH dependent hydrolysis of HPNP, with maximum efficiency at ca. pH 8.2, and with a half-lifetime of ∼1 h, the 1Ln and 3Ln complexes were found to be inactive, emphasizing the importance of the nature of the pyridine isomer as a cofactor in the hydrolytic process.     

A very short uranium-uranium bond: the predicted metastable U(2)2+

Quantum chemical calculations, based on multiconfigurational wave functions and including relativistic effects, show that the U(2)2+ system has a large number of low-lying electronic states with S of 0 to 2 and Lambda ranging from zero to ten. These states share a very small bond length of about 2.30 A, compared to 2.43 A in neutral U2. The Coulomb explosion to 2 U+ lowers the energy by only 1.6 eV and is separated by a broad barrier.     

Unexpected behavior of the reaction between acyl thioformanilides and acetonitrile derivatives—a useful entry to new penta-substituted dipyrrole disulfides

A convenient and unexpected synthesis of penta-substituted dipyrrole disulfides starting from readily available acyl thioformanilides and acetonitrile derivatives has been developed. The overall process leads to the creation of two C-C bonds, two C-N bonds, and one S-S bond with the concomitant formation of two pyrrole rings and disulfide from the fact that only two reagents need to be mixed together, and it complements the existing pyrrole disulfides chemistry.     

Phosphine-free cationic rhodium(I) complex-catalyzed disulfide exchange reaction: convenient synthesis of unsymmetrical disulfides

A phosphine-free cationic rhodium(I) complex, [Rh(cod)₂]BF₄, is an effective catalyst for disulfide exchange reaction of symmetrical disulfides to unsymmetrical disulfides under inert atmosphere. This reaction could be carried out using unpurified commercial grade solvents under air without decrease of yields and reaction rates.     

Anomalous behavior of saturated aqueous tungstate solutions

Potentiometric measurements on a freshly prepared saturated silver tungstate solution at 25°C indicate the existence of at least four different ionic tungstate species in this solution leading to the formation of a four-component precipitate. Solubility measurements have been carried out on saturated aqueous silver tungstate solutions at 25°C at different ionic strengths and at various pH. An attempt is made to explain the appearance of the solubility curves. Conductivity measurements on saturated sodium tungstate solutions indicate a phase transition of solid sodium tungstate at 36.5±1.0°C. The assumption of a phase transition is supported by DTA and TGA measurements.Presentation to First International Symposium on Solubility Phenomena, University of Western Ontario, London, Ontario, August 21–23, 1984.     

Synergistic behavior of sodiumdodecylsulfate and 1,2-diheptanoyl-sn- glycero-3-phosphocholine in an aqueous medium: interfacial and bulk behavior

The synergistic behavior of sodiumdodecylsulfate (SDS) and 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC) binary mixtures has been studied with interfacial and pyrene fluorescence(I ₁/ I ₃) intensity measurements. From the interfacial data, the interfacial parameters; the maximum surface excess (Γ_max), or the minimum area per molecule (A _min), and the surface pressure at the critical micellar concentration (π_cmc) have been evaluated. The cmc value has been used for evaluating the free energies of micellization (ΔG ^o _m). The mixed micelle formation was evaluated with the help of the Clint equation. The SDS plus DHPC mixed micelles showed negative departure from ideality indicating synergistic interactions between the unlike components. The quantitative analysis of mixed micelle, mixed monolayer and the composition of the mixed micelle was carried out with the help of regular solution approximation. The interaction parameters, β and β^σ, in the mixed micelle as well as in the mixed monolayer, respectively showed negative values indicating synergistic behavior of SDS and DHPC molecules.     

Co3O4-SiO2 nanocomposite: a very active catalyst for CO oxidation with unusual catalytic behavior

A high surface area Co(3)O(4)-SiO(2) nanocomposite catalyst has been prepared by use of activated carbon as template. The Co(3)O(4)-SiO(2) composite, the surface of which is rich in silica and Co(II) species compared with normal Co(3)O(4), exhibited very high activity for CO oxidation even at a temperature as low as -76 °C. A rather unusual temperature-dependent activity curve, with the lowest conversion at about 80 °C, was observed with a normal feed gas (H(2)O content ~3 ppm). The U-shape of the activity curve indicates a negative apparent activation energy over a certain temperature range, which has rarely been observed for the heterogeneously catalyzed oxidation of CO. Careful investigation of the catalytic behavior of Co(3)O(4)-SiO(2) catalyst led to the conclusion that adsorption of H(2)O molecules on the surface of the catalyst caused the unusual behavior. This conclusion was supported by in situ diffuse reflectance Fourier transform infrared (DRIFT) spectroscopic experiments under both normal and dry conditions.     

Synthesis of new amidino-substituted 2-aminothiophenoles: mild basic ring opening of benzothiazole

The efficient synthesis of new amidino, N-isopropylamidino, 2-imidazolinyl substituted benzothiazoles and 2-aminothiophenoles by the Pinner reaction is described. The novel ring opening of benzothiazole with ammonia and ethylenediamine was found, and a plausible reaction mechanism proposed. The ring opening with ethylenediamine is selective and applicable to compounds bearing hydrolytically and amonolytically unstable substituents. Different amidino-substituted 2-aminothiophenoles were isolated in zwitterionic and disulfide form and their structures were determined by X-ray crystal structure analysis.     

Synthesis and aggregational behavior of acidic proteinoid

Polypeptide-based acidic proteinoid containing L -glutamic acid and L -aspartic acid in excess and five other neutral and basic amino acids in minor proportions have been synthesized and found that it forms organized aggregates in an aqueous solution. The proteinoid aggregate has been characterized using ¹³C-NMR, IR, and fluorescence spectroscopic techniques. The c.m.c. of the proteinoid has been determined by conductometric and pH metric methods. The aggregation studies were carried out at different temperatures and varying ionic strengths of the medium. The phase transition of the proteinoid aggregate has been determined using the fluorescence absorbance method. The aggregation behavior is shown to be dependent on the pH of the solution. This was also supported by conductivity measurements. Using methylene blue as a model drug, the drug delivery property of the proteinoid micelles were studied in acidic (pH 4.5) and neutral (pH 7.4) mediums. Using biphasic model thermochemical parameters, ΔG, ΔH, ΔS, and ΔC_p have been evaluated. © 1996 John Wiley & Sons, Inc.     

Effect of multiple ionic species on the electrophoretic behavior of a charge-regulated particle

It is often assumed in the conventional electrophoresis analysis that the liquid phase contains only one kind of each cation and anion. That analysis is extended to the case where the liquid phase contains multiple ionic species in this study so that the conditions considered are closer to reality. Using a dispersion of SiO(2) particles, which is of a charge-regulated nature, as an example, where the dispersion pH is adjusted by HCl and NaOH, numerical simulation is conducted to examine the electrophoretic behaviors of the particle under various conditions. We show that the presence of multiple ionic species is capable of yielding profound and interesting electrophoretic behaviors, which are justified by the experimental data in the literature. In addition, we show that two types of double-layer polarization (DLP) are present that have not been reported previously in the electrophoresis analyses. Type I DLP, which reduces the mobility of a particle, occurs inside the double layer, and type II DLP, which raises that mobility, occurs immediately outside the double layer.     

Adsorptive refolding of a highly disulfide-bonded inclusion body protein using anion-exchange chromatography

α-Fetoprotein (AFP) is a prospective biopharmaceutical candidate currently undergoing advanced-stage clinical trials for autoimmune indications. The high AFP expression yields in the form of inclusion bodies in Escherichia coli renders the inclusion body route potentially advantageous for process scale commercial manufacture, if high-throughput refolding can be achieved. This study reports the successful development of an ‘anion-exchange chromatography’-based refolding process for recombinant human AFP (rhAFP), which carries the challenges of contaminant spectrum and molecule complexity. rhAFP was readily refolded on-column at rhAFP concentrations unachievable with dilution refolding due to viscosity and solubility constraints. DEAE-FF functioned as a refolding enhancer to achieve rhAFP refolding yield of 28% and product purity of 95% in 3 h, at 1 mg/ml protein refolding concentration. Optimization of both refolding and chromatography column operation parameters (i.e. resin chemistry, column geometry, redox potential and feed conditioning) significantly improved rhAFP refolding efficiency. Compared to dilution refolding, on-column rhAFP refolding productivity was 9-fold higher, while that of off-column refolding was more than an order of magnitude higher. Successful demonstration that a simple anion-exchange column can, in a single step, readily refold and purify semi-crude rhAFP comprising 16 disulfide bonds, will certainly extend the application of column refolding to a myriad of complex industrial inclusion body proteins.     

Effect of stress-jump condition on electrophoretic behavior of a spherical dispersion of soft particles

The electrophoresis of a concentrated dispersion of soft particles, where a particle comprises a rigid core and an ion-penetrable membrane layer, is modeled theoretically, taking the effect of double-layer polarization into account. In particular, the influence of a stress-jump condition of the flow field at the membrane layer-liquid interface on the electrophoretic mobility of a particle is investigated. The type of particles considered mimic biocolloids, such as cells and microorganisms, and inorganic colloids covered by an artificial polymer layer such as surfactant molecules. A unit cell model is adopted to simulate the present spherical dispersion, and the governing equations and the associated boundary conditions are solved by a pseudo-spectral method based on Chebyshev polynomials. We show that while the stress-jump condition, characterized by a stress-jump coefficient, can have a significant influence on the mobility of a particle, the associated flow field is not influenced appreciably. Also, the influence of the stress-jump condition on the mobility of a particle depends largely on the nature of the membrane layer, characterized by its friction coefficient.