Mapping of possible prion protein self-interaction domains using peptide arrays

Background  

The common event in transmissible spongiform encephalopathies (TSEs) or prion diseases is the conversion of host-encoded protease sensitive cellular prion protein (PrP^C) into strain dependent isoforms of scrapie associated protease resistant isoform (PrP^Sc) of prion protein (PrP). These processes are determined by similarities as well as strain dependent variations in the PrP structure. Selective self-interaction between PrP molecules is the most probable basis for initiation of these processes, potentially influenced by chaperone molecules, however the mechanisms behind these processes are far from understood. We previously determined that polymorphisms do not affect initial PrP^C to PrP^Sc binding but rather modulate a subsequent step in the conversion process. Determining possible sites of self-interaction could elucidate which amino acid(s) or amino acid sequences contribute to binding and further conversion into other isoforms. To this end, ovine – and bovine PrP peptide-arrays consisting of 15-mer overlapping peptides were probed with recombinant sheep PrP^C fused to maltose binding protein (MBP-PrP).     

Mercurimetrische Bestimmung von organisch gebundenem Chlor und Brom im Dezimilligrammbereich

Zusammenfassung Zur Bestimmung von Chlor und Brom in organischen Verbindungen im Dezimilligrammbereich werden Substanzmengen von 0,2 bis 2 mg im Sauerstoffstrom in einem mit Quarzkörnern gefüllten Verbrennungsrohr bei 1000° verbrannt und die Oxydationsprodukte in einem kleinen Perlenrohr mit Wasserstoffperoxydlösung absorbiert. Nach Ausspülen des Perlenrohres mit Isopropanol erfolgt die Endbestimmung durch Titration mit 0,01-n bzw. 0,1-n Quecksilberperchloratlösung.

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Summary To determine chlorine and bromine in organic compounds in the decimilligram range, samples weighing from 0.2 to 2 mg were burned at 1000° in a stream of oxygen in a combustion tube filled with quartz grains. The oxidation products were absorbed in a solution of hydrogen peroxide in a small bead tube. After the latter was rinsed out with isopropanol, the final determination was made by titration with 0.01 or 0.1N mercury perchlorate solution.

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Résumé Afin de doser le chlore et le brome dans les composés organiques, dans le domaine du décimilligramme, on a brûlé dans un courant d'oxygène à 1000° des quantités de substance de 0,2 à 2 mg, dans un tube à combustion rempli de grains de quartz et l'on a absorbé les produits d'oxydation dans l'eau oxygénée d'un petit tube à perles. Après lavage du tube à perles par l'isopropanol, on effectue le dosage final en titrant par une solution de perchlorate de mercure 0,01 ou 0,1N.

     

Lipophilic Diamides as Ionophores for Alkali and Alkaline Earth Metal Cations

A series of lipophilic N, N, N′,N′-tetrasubstituted diamides were prepared and their selectivity in solvent polymeric membranes was studied, cis-N, N, N′, N′-Tetraisobutylcyclohexane-1,2-dicarboxamide induces a selectivity in membranes for Li⁺over alkaline earth metal cations and other alkali metal cations by a factor of about 1000 and 100 respectively. The ionophore N, N′-diheptyl-N,N′-dimethylethylmalonamide is an attractive candidate for the use in microelectrodes for the determination of intracellular Mg²⁺-activities.     

An Improved Method for Site‐Specific End Modification of Zeolite L for the Formation of Zeolite L and Gold Nanoparticle Self‐Assembled Structures

The ability to site‐selectively modify micro‐ and nanosized particles has allowed for directed self‐assembly in two and three dimensions. Site‐selective modification of particles can be a complicated task requiring the pre‐organization of particles or enhanced particle fabrication methods. The aluminum silicate, zeolite L has been reported to undergo site‐specific modification at the zeolite channel entrances, post‐fabrication in a solution‐based method. The process by which the channel entrances are site selectively modified is explored here. The preliminary step of charging the zeolite channels with aqueous acid allows for catalysis of covalent bond formation at the channel entrances. Three new end‐specific modification reagents are described based on silanol and silyl ether functional groups. These reagents are purified by column chromatography and characterized by¹H NMR spectroscopy and high resolution mass spectrometry (HRMS); they provide for reliable end modification of zeolites L. Preferential reactivity at the channel entrances is also observed. The utility of the approach is demonstrated by modifying zeolite L with adamantane at the channel entrances. Site‐specific self‐assembly with β‐cyclodextrin coated gold nanoparticles can be triggered with a chemical stimulus. The resulting multivalent host‐guest interactions give gold clustered nanoparticles at the ends of the micrometer‐sized zeolites.     

Studies on photoinduced effects in pulse-electrodeposited Ag/Hg-1212/CdSe hetero-nanostructures

Metal/superconductor/semiconductor (Ag/Hg-1212/CdSe) hetero-nanostructures have been fabricated using pulse-electrodeposition technique and are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The junction capacitance of Ag/Hg-1212, Hg-1212/CdSe and Ag/Hg-1212/CdSe heterojunctions is measured in dark and under laser irradiation at room temperature. The nature of the junction formed and built-in-junction potentials were determined. The increase in carrier concentration across the junction due to photo-irradiation has been observed.     

Effect of laser irradiation of C-V characteristics of electrodeposited Ag/Tl-2223/CdSe hetero-nanostructures

One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation, metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction built-in-potential (V _D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied.     

Lipophilic Di- and Triamides as Ionophores for Alkaline Earth Metal Cations

Different electrically neutral lipophilic di- and triamides were prepared and their ion selectivity in membranes studied. In membranes the ionophore N, N′-diheptyl-N, N′-dimethyl-succinamide prefers Ca²⁺ over Mg²⁺ by a factor of 20 but rejects Na⁺ and K⁺ in respect to Mg²⁺ by a factor of 100 and 10, respectively. This selectivity suffices to perform useful intracellular Mg²⁺ activity studies.     

Quantitative organische Elementaranalyse im Dezimilligrammbereich. III

Zusammenfassung Es wird eine Methode zur Bestimmung des Schwefels und zur Bestimmung von Schwefel und Chlor (Brom) ineiner Einwaage beschrieben. Substanzmengen zwischen 0,1 und 1,5 mg werden im Sauerstoffstrom bei zirka 1000° in einem mit Quarzperlen gefüllten Verbrennungsrohr verbrannt und die Verbrennungsprodukte in einem mit Wasserstoffperoxydlösung benetzten Mikro-Perlenrohr absorbiert. Die Titration des entstandenen Sulfates erfolgt mit 0,02-n Bariumperchlorat und Thorin als Indikator. Im Anschluß kann vorhandenes Chlorid (Bromid) mercurimetrisch titriert werden.Die erzielte Genauigkeit entspricht den Anforderungen der Elementaranalyse.

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Summary A method is described for determining sulfur and also sulfur and chlorine (bromine) in a single sample. Amounts of the substance between 0.1 and 1.5 mg are burned in a stream of oxygen at around 1000° C in a combustion tube charged with quartz granules, and the combustion products are absorbed in a micro-bead tube moistened with a solution of hydrogen peroxide. The sulfate formed is titrated with 0.02N barium perchlorate with thorine as indicator. Any chloride (bromide) present can then be titrated mercurimetrically.The precision attained meets the demands of ultimate analysis.

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Résumé On décrit une méthode pour le dosage du soufre et pour le dosage du soufre et du chlore (ou du brome) surune seule prise d'essai. On réalise la combustion de quantités de substances comprises entre 0,1 et 0,5 mg dans un courant d'oxygène, à environ 1000°, dans un tube à combustion rempli de grains de quartz et l'absorption des produits de combustion s'effectue au moyen d'un micro-tube à perles mouillées par une solution d'eau oxygénée. On réalise le titrage du sulfate formé par le perchlorate de baryum 0,02N et le thorin comme indicateur. Pour finir, on peut titrer le chlorure (ou le bromure) présent, par mercurimétrie.L'exactitude obtenue correspond aux exigences de l'analyse élémentaire.