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71.
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Abachi S Akerlof C Baringer P Blockus D Brabson B Brom J Bylsma BG Chapman J Cork B DeBonte R Derrick M Errede D Gan KK Jung C Ken MT Koltick D Kooijman P Loeffler FJ Loos JS Low EH McIlwain RL Meyer DI Miller DH Musgrave B Neal H Ng CR Nitz D Ogren H Paik HW Price LE Rangan LK Repond J Rust DR Shibata EI Sugano K Thun R Tschirhart R 《Physical review letters》1987,59(22):2519-2522
74.
Abachi S Baringer P Bylsma BG DeBonte R Koltick D Loeffler FJ Low EH McIlwain RL Miller DH Ng CR Rangan LK Shibata EI Derrick M Gan KK Kooijman P Loos JS Musgrave B Price LE Repond J Sugano K Weiss JM Wood DE Blockus D Brabson B Brom J Jung C Ogren H Rust DR Akerlof C Chapman J Errede D Kesten P Meyer DI Nitz D Seidl AA Thun R Willutzky M Cork B 《Physical review letters》1986,57(16):1990-1993
75.
T. Rösel P. Schlemmer J. Röder L. Frost K. Jung H. Ehrhardt 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,23(4):359-363
A new method, and first results for an impact energy 2 eV above the threshold of ionisation of helium, are presented for the measurement of absolute triple differential cross sections (TDCS) in a crossed beam experiment. The method is based upon measurement of beam/target overlap densities using known absolute total ionisation cross sections and of detection efficiencies using known absolute double differential cross sections (DDCS). For the present work the necessary absolute DDCS for 1 eV electrons had also to be measured. Results are presented for several different coplanar kinematics and are compared with recent DWBA calculations. 相似文献
76.
Photodissociation at 266 nm of protonated synthetic polypeptides containing a tryptophanyl residue was investigated using a homebuilt tandem time-of-flight mass spectrometer equipped with a matrix-assisted laser desorption/ionization source. Efficient photodissociation of the protonated peptides was demonstrated. Most of the intense peaks in the laser-induced tandem mass spectra were sequence ions. Furthermore, sequence ions due to cleavages at all the peptide bonds were observed; this is a feature of the technique that is particularly useful for peptide sequencing. Fragmentations at both ends of the tryptophanyl residue were especially prevalent, which can be useful for location of the tryptophanyl chromophore in a peptide. 相似文献
77.
Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co(2)Rh(2)(CO)(12) react with alkynes and alpha,beta-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. alpha,beta-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones. 相似文献
78.
[reaction: see text] Anomalous ozonolysis of strained bicyclic allylic alcohols yields alpha-hydroxymethyl ketones. The proposed mechanism involves an unusual trapping of the primary ozonide that undergoes a Grob-like fragmentation instead of dissociating into the Criegee intermediates. 相似文献
79.
CHIP-mediated hyperubiquitylation of tau promotes its self-assembly into the insoluble tau filaments
Ji Hyeon Kim Jeeyoung Lee Won Hoon Choi Seoyoung Park Seo Hyeong Park Jung Hoon Lee Sang Min Lim Ji Young Mun Hyun-Soo Cho Dohyun Han Young Ho Suh Min Jae Lee 《Chemical science》2021,12(15):5599
The tau protein is a highly soluble and natively unfolded protein. Under pathological conditions, tau undergoes multiple post-translational modifications (PTMs) and conformational changes to form insoluble filaments, which are the proteinaceous signatures of tauopathies. To dissect the crosstalk among tau PTMs during the aggregation process, we phosphorylated and ubiquitylated recombinant tau in vitro using GSK3β and CHIP, respectively. The resulting phospho–ub-tau contained conventional polyubiquitin chains with lysine 48 linkages, sufficient for proteasomal degradation, whereas unphosphorylated ub-tau species retained only one–three ubiquitin moieties. Mass-spectrometric analysis of in vitro reconstituted phospho–ub-tau revealed seven additional ubiquitylation sites, some of which are known to stabilize tau protofilament stacking in the human brain with tauopathy. When the ubiquitylation reaction was prolonged, phospho–ub-tau transformed into insoluble hyperubiquitylated tau species featuring fibrillar morphology and in vitro seeding activity. We developed a small-molecule inhibitor of CHIP through biophysical screening; this effectively suppressed tau ubiquitylation in vitro and delayed its aggregation in cultured cells including primary cultured neurons. Our biochemical findings point to a “multiple-hit model,” where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process, thus indicating that targeting tau ubiquitylation may be an effective strategy to alleviate the course of tauopathies.Multiple-hit model for tau aggregation, where sequential events of tau phosphorylation and hyperubiquitylation function as a key driver of the fibrillization process. 相似文献
80.
Kim HG Lee CW Yun S Hong BH Kim YO Kim D Ihm H Lee JW Lee EC Tarakeshwar P Park SM Kim KS 《Organic letters》2002,4(22):3971-3974
[formula: see text] A new molecular system, 2,11-dithio[4,4]metametaquinocyclophane containing a quinone moiety, was designed and synthesized. As the quinone moiety can readily be converted into an aromatic pi-system (hydroquinone) upon reduction, the nanomechanical molecular cyclophane system exhibits a large flapping motion like a molecular flipper from the electrochemical redox process. The conformational changes upon reduction and oxidation are caused by changes of nonbonding interaction forces (devoid of bond formation/breaking) from the edge-to-face to face-to-face aromatic interactions and vice versa, respectively. 相似文献