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21.
Fernando Formaggio Cristina Peggion Marco Crisma Claudio Toniolo Luba Tchertanov Jean Guilhem Jean‐Paul Mazaleyrat Yolaine Goubard Anne Gaucher Michel Wakselman 《Helvetica chimica acta》2001,84(2):481-501
A variety of model peptides, including four complete homologous series, to the pentamer level, characterized by the recently proposed binaphthyl‐based, axially chiral, Cα‐tetrasubstituted, cyclic α‐amino acid Bin, in combination with Ala, Gly, or Aib residues, was synthesized by solution methods and fully characterized. The solution conformational propensity of these peptides was determined by FT‐IR absorption and 1H‐NMR techniques. Moreover, the molecular structures of the free amino acid (S)‐enantiomer and an Nα‐acylated dipeptide alkylamide with the heterochiral sequence ‐(R)‐Bin‐Phe‐ were assessed in the crystal state by X‐ray diffraction. Taken together, the results point to the conclusion that β‐bends and 310 helices are preferentially adopted by Bin‐containing peptides, although the fully extended conformation would also be adopted in solution by the short oligomers to some extent. We also confirmed the tendency of (R)‐Bin to fold a peptide chain into right‐handed bend and helical structures. The absolute configuration of the Bin residue(s) was correlated with the typically intense exciton‐split Cotton effect of the 1Bb binaphthyl transition near 225 nm. 相似文献
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High-speed analysis of multiplexed short tandem repeats with an electrophoretic microdevice 总被引:3,自引:0,他引:3
Mitnik L Carey L Burger R Desmarais S Koutny L Wernet O Matsudaira P Ehrlich D 《Electrophoresis》2002,23(5):719-726
We report the development of a robust and effective method for multiplexed short tandem repeat (STR) analysis within a chip-based microdevice. The method uses a laser-induced fluorescence detection system and simultaneously detects three- and four-color multiplexed polymerase chain reaction (PCR) samples. Analyses of the eight combined DNA index system (CODIS) STR loci were performed in 20 min with single-base-pair resolution ranging from 0.75 to 1. A simultaneous analysis of fifteen loci-ladders and a gender marker Amelogenin based on the PowerPlexTM 16 System was achieved in less than 35 min. The system is capable of repetitive operation and may be extended to high-throughput multilane devices that could be readily interfaced to an automated sample loading system. 相似文献
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Synthesis,structure and biological activity of new 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐organylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles
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Luba Ignatovich Jana Spura Velta Muravenko Sergey Belyakov Juris Popelis Irina Shestakova Ilona Domrachova Anita Gulbe Zhanna Rudevica Ainars Leonchiks 《应用有机金属化学》2015,29(11):756-763
New 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐alkylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles (IC50: 1–6 µg ml?1) have been prepared by the condensation of corresponding silicon‐ and germanium‐containing furyl(thienyl)‐2‐carbaldehydes with 3‐cyano‐4,6,6‐trimethyl‐5,6‐dihydropyran‐2‐one using piperidine acetate as a catalyst. The obtained carbonitriles were identified using NMR (1H, 13C and 29Si) spectroscopy and GC‐MS. The structure of 6,6‐dimethyl‐2‐oxo‐4‐[2‐(5‐trimethylsilyl)thiophen‐2‐yl]‐5,6‐dihydro‐2H‐pyran‐3‐carbonitrile was studied using X‐ray diffractometry. The influences of the heterocycle and the structure of the organoelement substituent on cytotoxicity and on matrix metalloproteinase inhibition have been studied. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Luba Ignatovich Velta Muravenko Jana Spura Jury Popelis Ilona Domrachova Irina Shestakova 《应用有机金属化学》2013,27(7):406-411
Novel 2‐[(3‐aminopropyl)dimethylsilyl]‐5‐furfural diethylacetals and 2‐[(3‐aminopropyl)di‐methylsilyl]‐5‐phenylfurans have been synthesized by a hydrosilylation reaction of aliphatic and heterocyclic N‐allylamines in the presence of the Speier's catalyst. The effects of the structure of the amine and nature of organic substituent at the furan ring on the cytotoxicity of the new compounds have been studied. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Lipovsky A Levitski L Tzitrinovich Z Gedanken A Lubart R 《Photochemistry and photobiology》2012,88(1):14-20
Photoexcited TiO(2) has been found to generate reactive oxygen species, yet the precise mechanism and chemical nature of the generated oxy species especially regarding the different crystal phases remain to be elucidated. Visible light-induced reactions of a suspension of titanium dioxide (TiO(2)) in water were investigated using electron paramagnetic resonance (EPR) coupled with the spin-trapping technique. Increased levels of both hydroxyl (˙OH) and superoxide anion (˙O(2)(-)) radicals were detected in TiO(2) rutile and anatase nanoparticles (50 nm). The intensity of signals assigned to the ˙OH and ˙O(2)(-) radicals was larger for the anatase phase than that originating from rutile. Moreover, illumination with visible (nonUV) light enhanced ˙O(2)(-) formation in the rutile phase. Singlet oxygen was not detected in water suspension of TiO(2) neither in rutile nor in anatase nanoparticles, but irradiation of the rutile phase with visible light revealed a signal, which could be attributed to singlet oxygen formation. The blue part of visible spectrum (400-500 nm) was found to be responsible for the light-induced ROS in TiO(2) nanoparticles. The characterization of the mechanism of visible light-induced oxy radicals formation by TiO(2) nanoparticles could contribute to its use as a sterilization agent. 相似文献
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Tomasz ?ojewski Katarzyna Zi?ba Arkadiusz Knapik Jacek Bagniuk Anna Lubańska Joanna ?ojewska 《Applied Physics A: Materials Science & Processing》2010,100(3):809-821
The study presents an overview of the chromatographic (SEC), spectroscopic (FTIR, UV/VIS), viscometric (DP) and chemical methods
(titration, pH) used for the evaluation of the degradation progress of various kinds of paper under various conditions. The
methods were chosen to follow different routes of paper degradation. Model paper samples represented boundary paper types
from pure cellulose cotton paper, through softwood to low quality acidic, sized groundwood paper The accelerated ageing conditions
were adjusted to achieve maximum effect (climatic chamber RH 59%, 90oC) and also to mimic the environment inside books (closed vials). The results were settled on the literature data on the degradation
mechanisms and compared in terms of the paper types and ageing conditions. The estimators of coupled de-polymerisation and
oxidation have been proposed based on the correlation between SEC, UV/VIS and titrative coppper number determination. The
overall oxidation index derived from FTIR results was shown to correlate with the summary –CHO and –COOH concentration determined
by titrative methods. 相似文献
30.
Luba Tchertanov 《Supramolecular chemistry》2013,25(1):67-91
Abstract The complexation and supramolecular recognition of two polyfunctional anions, thiocyanate and azide, have been analysed using the X-ray structural data retrieved from the Brookhaven Protein Database (for macromolecules) and the Cambridge Structural Database (for small molecule structures). The following structural aspects have been considered: - hydrogen-bond acceptor function of the anions; - analysis of the coordination features of anions with the metals; - influence of metal complexation on the H-donor accepting properties of the anions. Lastly, a comparison of the modes of binding of the two anionic substrates was carried out. Their extraordinary activity as hydrogen-bond acceptors allows these anions to serve as a strong bridge between different molecular fragments. The coordination of thiocyanate or azide anion by the metal atoms in coordination compounds gives rise to a redistribution of anionic charge in both entities which in turn, controls the hydrogen-bonding acceptor properties of the terminal atom of the anion. The results presented in this paper provide structural information of the role of anion binding in proteins and to our knowledge, afford the first study of the binding behaviour of thiocyanate and azide in systematic manner. 相似文献