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).     

Flow-Injection Determination of Gold(III) Based on Its Catalytic Effect on the Peroxodisulfate Oxidation of Bromopyrogallol Red

It was found by derivative spectrophotometry that gold(III) ions exhibit a significant catalytic effect on the peroxodisulfate oxidation of Bromopyrogallol Red in slightly acidic chloride–citrate solutions. It was shown that if this catalytic reaction is implemented in a three-channel flow-injection system, the intensity of the signal due to a decrease in the reagent color is proportional to the concentration of gold(III) in the injected solution and depends on the reagent concentrations, pH, and the temperature of the solution as well as on the sample volume, flow rates, and the length of the reaction coil. The conditions assuring the kinetic masking of foreign ions in the injected solution were found. The possibilities of the flow-injection determination of 0.004–1.00 g/mL gold(III) in the presence of copper, iron, and many other concomitant elements were found. The average throughput of the analytical system is 200 h^–1 for a sample volume of 500 L. The performance characteristics of the procedure were estimated in the analysis of synthetic mixtures simulating the rinsing waters of gilding baths.     

Principles of modeling in the study of conformations of histones

A study has been made by the CD method of the conformational potentialities of the polypeptides (Gly-Lys-Gly)_n and (Ala-Lys-Ala)_n and fragments of the terminal sections of histones H4 (the sequence 1–16), H2B (1–21), and H1 (152–184), and they have been used as models of histones in complex formation with DNA under various conditions of the medium.V. I. Nikitin Institute of Chemistry, Tadzhik SSR Academy of Sciences, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 391–398, May–June, 1989.     

Oxidation of isoprene by molecular oxygen in the presence of the tetraphenylporphin complex of divalent manganese

Conclusions The oxidation of isoprene proceeds regioselectively with the formation of 2-methyl-2-buten-1-ol. This oxidation is more rapid for isoprene than for 2-methyl-2-pentene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 214–215, January, 1986.     

Comparative investigation of the structure of complexes of DNA with the polypeptide fragment 152–184 of histone H1 and the polypeptide (Lys-Ala-Ala)n

The interactions with DNA of a synthetic peptide fragment of histone H1 33 amino acid residues long the sequence of which corresponds to fragment 152–184 and of a synthetic polypeptide (Lys-Ala-Ala)_n modeling the properties of the C-terminal fragments of histone H1 have been studied by the CD method. The use of the CD method for recording the spectra of the polypeptides under investigation in the free state and of the artificial complexes of DNA formed with them has permitted the characterization of different structural possibilities of the polypeptides in solution and of their complexes with DNA, and the conformational changes of the components of the complex under various ionic conditions.     

Spin-label study of the conformational states of polypeptide models of histones

The conformational states of the regular polypeptides (Gly-Lys-Gly)_n, (Ala-Orn-Gly)_n, and (Ala-Orn-Ala)_n have been studied by the spin-label method. Their behavior in solutions of guanidine hydrochloride and urea and in solutions of salts of bivalent metals does not contradict the presence of an extended levohelical conformation in their polypeptide chains. In CaCl₂ (5 N) solutions the polypeptides exhibit aggregation properties. A study of the behavior of the poly peptide at these temperatures has shown that with a rise in temperature there is a monotonic change in the structures of the polypeptide chains that is characteristic for a conformation of the polyproline-II type. Differences have been observed in the behavior of glycine-and alanine-containing polypeptides in the presence of sodium dodecyl sulfate with a change in the temperature.V. I. Nikitin Institute of Chemistry of the Academy of Sciences of the Tadzhik SSR, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 218–222, March–April, 1986.     

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.