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).     

Die Gasphasenintercalation von Graphit durch SbCl4F

Gas Phase Intercalation of Graphite by SbCl₄F Gas Phase Intercalation of Graphite by SbCl₄F using a two-zone technique is a method to prepare intercalation compounds of different stage index n in temperature range between 120 and 140°C. The reaction is a process of successive decrease of stage index. Increasing the reaction time, i. e. concentration, regions of pure stages alternate with two-phase regions. Intercalation compounds were characterized by X-ray technique, EPMA, and chemical methods. The compounds are stable in ordinary air, with aqueous HCl as well as KOH only pentavalent but not any trivalent antimony can be removed. The identity periods along c-axis in pure stages are I_c = 9.33 Å (n = 1), 12.72 Å (n = 2), 16.06 Å (n = 3) and 19.40 Å (n = 4). A (√7 × √ 7) 19.1° in-plane structure of intercalants was found. The uptake curve of mass with time reveals a discontinuity connected with formation of stage 2. Concave shape of curve during starting period at 120 and 125°C will be interpreted as a consequence of an induction time. From X-ray and EPMA studies it may be concluded that nucleation at the prismatic crystal edges controls the kinetics of reaction. Assuming a first order kinetics of filling the vacant sites, the same activation energy in case of formation of stage 1 and stage 2 have been determined approximately (97 and 102 kJ/mol).     

Massenspektrometrische Untersuchungen an einigen Halogeniden der 5. Haupt- und Nebengruppe

The mass spectra of fifth group halids and some of their substitution products have been studied. Fragmentation processes, charge distributions as well as relative stabilities of fragment ions and double-charged ions are discussed. Appearance potentials have been measured and discussed, with reference to decomposition reactions and abundance considerations of fragment ions. In some cases polymeric ions were found in mass spectra.     

Pore formation during the pyrolysis of C-Nb2O5 and C-Ta2O5 xerogels

Binary organic-inorganic gels have been prepared by mixing a carbonaceous hydrosol and a Nb₂O₅ or Ta₂O₅ sol derived by hydrolysis of the alkoxides. The gels are pyrolyzed under an inert atmosphere into precursors in which carbon and the metal oxides are mixed very intimately. High temperature treatment converts the precursors into the cubic face centered carbides. The precursors as well as the carbides have been shown to be micro- and mesoporous materials. Measurements of nitrogen adsorption reveal a characteristic change of the shapes of the isotherms (Type I Type IV) and of the hysteresis loops (H4H2H1) during the thermal processes. Pore widening has been observed with rising temperature. The phenomena of crystallization, carbothermal reduction and sintering were found to control the pore shape and size. The results of the adsorption measurement correlate well with those of the thermoanalytical and X-ray diffraction studies.Dedicated to Professor Dr. rer.nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Komplexometrische Phosphatbestimmung

Zusammenfassung In Mitteilung I ist ein Verfahren für die maßanalytische Bestimmung von Phosphat in reinen Lösungen von Phosphorsäure oder Alkaliphosphaten beschrieben worden, bei dem Phosphat als Ammoniumzinkphosphat gefällt und nach der Auflösung von Ammoniumzinkphosphat Zink komplexometrisch titriert wird.In Mitteilung II wird dieses Verfahren auf technisch wichtige Produkte angewendet. Bei dieser Anwendung sind der maßanalytischen Bestimmung Aufschlüsse und Fällungen von Ammoniumphosphormolybdat bzw. Ammoniummagnesiumphosphat vorgeschaltet.Es werden Arbeitsvorschriften für die Überführung von Ammoniumphosphormolybdat bzw. Ammoniummagnesiumphosphat in Ammoniumzinkphosphat gegeben, das nach der Auflösung wie in Mitteilung I titriert werden kann.Die Leistungsfähigkeit des Verfahrens wird diskutiert. Es ist schneller als ein Verfahren mit gravimetrischer Endbestimmung. Es ist zur Serienanalyse geeignet.Die Untersuchung wurde mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.I. Mitteilung: H.Buss, H. W.Kohlschütter u. M.Preiss: diese Z.193, 264 (1963).     

Synthesis of Chiral 12-Phenyl(2H)dodecanoic Acids: Useful metabolic probes for the biosynthesis of 1-alkenes from fatty acids

The synthesis of chiral 12-phenyi(²H)dodecanoic acids as metabolic probes for the evaluation of the stereo-chemical course of the biosynthesis of 1-alkerses from fatty acids in plants and insects is described. The diastereoisomeric (2R, 3R)- or (2S, 3S)-12-phenyl(2,3?²H₂)dodecanoic acids 11 are obtained in high chemical and optical yield (>97% e.e.) from the readily available (E)-12-phenyl(2,3-²H₂)dodec-2-enoic acid ( 10 ) or (E)-12-phenyldodec-2-enoic acid ( 10a ) by microbial reduction with wet packed cells of Clostridium tyrobutyricum in either ²H₂O or H₂O buffer. (2R)- and (2S)-12-phenyl(2?²H)dodecanoic acids 9 (>97% e.e.) are accessible from the allylic alcohol 6 via Sharpless epoxidation with (+)-L- or (?)-D-diethyl tartrate, Synthetic routes to the (E)- and (Z)-11-phenyl(1?²H) undec-1-enes 16 and 16a as reference compounds are also included.     

The Influence of Mineral Impurities on the „Sulphur Puffing”︁ at High Temperature Treatment of Brown Coal Pitch Cokes

Cokes rich in sulphur usually show throughout the high temperature treatment between 1500 and 1800 °C an irreversible dilatation which can be suppressed by additives of inorganic oxides or salts. In brown coal pitch cokes with high content of sulphur and mineral impurities (ash), however, this suphur puffing cannot be observed. Basic ash components (e. g. CaO, Fe₂O₃, MgO) are responsible for the puffing inhibition. The inhibition is already sufficient if the concerntration of basic ash components equals the suphur conentration.