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1.
Alan Rigter Jan PM Langeveld Drophatie Timmers-Parohi Jorg G Jacobs Peter LJM Moonen Alex Bossers 《BMC biochemistry》2007,8(1):6
Background
The common event in transmissible spongiform encephalopathies (TSEs) or prion diseases is the conversion of host-encoded protease sensitive cellular prion protein (PrPC) into strain dependent isoforms of scrapie associated protease resistant isoform (PrPSc) 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 PrPC to PrPSc 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 PrPC fused to maltose binding protein (MBP-PrP). 相似文献2.
3.
Rondeau D Martineau C Blanchard P Roncali J 《Journal of mass spectrometry : JMS》2002,37(10):1081-1085
Oligothienylenevinylenes/C(60) dyads n-C and triads n-C(2) are studied by electrospray mass spectrometry. A clear correlation is observed between the nature of the charged species detected by mass spectrometry, i.e. protonated molecule [M + H], (+) cation radical M(+.) and dication M(++), and the oxidation potentials of the molecules. Moreover, under defined solubility conditions, mass spectrometry provides conclusive evidences for the reversible dimerization of cation-radicals of n-C(2) compounds. 相似文献
4.
We describe a method for the quantitative analysis of prostaglandin (PG) E2 and the major urinary metabolites PGI2 and thromboxane (Tx) A2 in human and in rat by combined gas chromatography and negative-ion chemical-ionization mass spectrometry. The procedure is based on the sequential use of small columns with distinct properties combined with a thin-layer chromatography step, for the extraction and the purification of urinary prostaglandins. The compounds are then analysed as their pentafluorobenzyl ester-O-methyloxime-trimethylsilyl ether derivatives, using either packed or capillary columns. Deuterated analogues are used as internal standards. The method was established by using tritiated prostaglandins covering the extremes of polarity in order to optimize the recovery of prostanoids as well as the quality of the chromatograms and spectra. The overall recovery was 24%. Standard curves were obtained by the same procedure and found to be reproducible, with a maximal day-to-day variation of +/- 5%. The relatively simple approach required for the sequential extraction and purification of prostaglandins on small columns of distinct properties, combined with the highly specific and highly sensitive method of detection, places this procedure among the most reliable method for measuring urinary prostanoids in both humans and animals. In addition, the procedure is faster than classical approaches and necessitates smaller amounts of samples and solvents. 相似文献
5.
Corrigendum: An NMR‐Driven Crystallography Strategy to Overcome the Computability Limit of Powder Structure Determination: A Layered Aluminophosphate Case 下载免费PDF全文
6.
Three-dimensional microfabrication by two-photon-initiated polymerization with a low-cost microlaser 总被引:3,自引:0,他引:3
Fabrication of submicrometer structures by two-photon-initiated polymerization is performed with an inexpensive and low-power microlaser. This is made possible by the design of photoinitiators with strong two-photon absorption cross sections. We analyze the influence of both material properties and irradiation conditions on the two-photon polymerization rate and show that resins based on our highly sensitive two-photon photoinitiator can be solidified with microlaser excitation, whereas commercial UV photoresins require ultrashort and intense laser pulses. 相似文献
7.
Kinetic measurements on the hydrolysis of some chlorosilanes have been performed in weak polar solvents, with a very low concentration of water (1–8 X 10?3 M), in the presence of nucleophilic agents: HMPT, DMSO, DMF. It is possible to show that the hydrolysis is promoted through a nucleophilic assistance localized on the silicon atom. This reaction is analogous to the racemisation of chlorosilanes. It is controlled by entropy of activation. 相似文献
8.
Martineau C Engelke F Taulelle F 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(2):311-319
The effects of multiple-resonance heteronuclear decoupling under magic angle spinning (MAS) on the resolution of one-dimensional 19F and 31P and various two-dimensional MAS NMR spectra and on the residual non-refocusable coherence lifetimes in fluorinated aluminophosphate AlPO4-CJ2, i.e. a compound that contains numerous highly abundant nuclei but no homonuclear spin bath, has been investigated. The design of the four-channel (1H, 19F, 27Al, 31P) MAS probe used for this study is first described. 1H and 1H–27Al double-resonance decouplings allows lengthening the optimized transverse relaxation and increasing the resolution in the 19F and 31P dimensions. Under the application of multi-nuclear decoupling, a two-dimensional 19F–31P CP-HETCOR correlation spectrum for AlPO4-CJ2 is recorded with unprecedented high-resolution in the two dimensions. Moreover, because 1H-decoupling increases the 19F , it has been applied during the entire duration of the 2D NMR experiments, allowing the direct use of residual small interactions to generate 19F–19F and 19F–27Al 2D NMR correlation spectra in AlPO4-CJ2. 相似文献
9.
Mäki JM Tuomisto F Varpula A Fisher D Khan RU Martineau PM 《Physical review letters》2011,107(21):217403
We have developed a method called optical transient positron spectroscopy and apply it to study the optically induced carrier trapping and charge transfer processes in natural brown type IIa diamond. By measuring the positron lifetime with continuous and pulsed illumination, we present an estimate of the optical absorption cross section of the vacancy clusters causing the brown color. The vacancy clusters accept electrons from the valence band in the absorption process, giving rise to photoconductivity. 相似文献
10.
Martineau C Fayon F Suchomel MR Allix M Massiot D Taulelle F 《Inorganic chemistry》2011,50(6):2644-2653
The room temperature structure of Ba(5)Al(3)F(19) has been solved using electron microscopy and synchrotron powder diffraction data. One-dimensional (1D) (27)Al and ultrafast magic-angle-spinning (MAS) (19)F NMR spectra have been recorded and are in agreement with the proposed structural model for Ba(5)Al(3)F(19). The (19)F isotropic chemical shift and (27)Al quadrupolar parameters have been calculated using the CASTEP code from the experimental and density functional theory geometry-optimized structures. After optimization, the calculated NMR parameters of both the (19)F and (27)Al nuclei show improved consistency with the experimental values, demonstrating that the geometry optimization step is necessary to obtain more accurate and reliable structural data. This also enables a complete and unambiguous assignment of the (19)F MAS NMR spectrum of Ba(5)Al(3)F(19). Variable-temperature 1D MAS (19)F NMR experiments have been carried out, showing the occurrence of fluorine ion mobility. Complementary insights were obtained from both two-dimensional (2D) exchange and 2D double-quantum dipolar recoupling NMR experiments, and a detailed analysis of the anionic motion in Ba(5)Al(3)F(19) is proposed, including the distinction between reorientational processes and chemical exchange involving bond breaking and re-formation. 相似文献