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981.
Ghitun M Bonneil E Fortier MH Yin H Killeen K Thibault P 《Journal of separation science》2006,29(11):1539-1549
This work reports on the application of a microfluidic device integrating nanoscale LC to nanoelectrospray MS (nano-LC-chip-MS) for the analysis of complex protein digests. Peak profile analyses of more than 700 peptide ions, reproducibly detected across replicate nano-LC-chip-MS runs (n = 5), indicated that the system provided RSD values of 0.24% on retention time, +/- 30 ppm on m/z measurement and +/- 30% variation on intensity over three orders of magnitude. RP adsorbant media with different alkyl chains and particle size packed in both trapping and separation channels were investigated to improve the chromatographic performance of this system. A two-fold improvement in chromatographic peak capacity was achieved using microfluidic devices comprising a 5 mircrom C3 trap with 2.5 microm C18 trap separation channel compared to the traditional 5 microm C18 stationary phase. Enhanced sample selectivity for the identification of phosphopeptides was obtained by combining immobilized metal affinity media prior to peptide separation on the RP microfluidic device. This system was evaluated in the context of differential phosphoproteome analyses to identify changes in signaling events and protein expression of human monocytes following the administration of phorbol ester. 相似文献
982.
Pigliucci A Nikolov P Rehaman A Gagliardi L Cramer CJ Vauthey E 《The journal of physical chemistry. A》2006,110(33):9988-9994
A series of 6-styryl-2,4-diphenylpyrylium salts exhibiting dual fluorescence has been investigated by fluorescence up-conversion in conjunction with quantum chemical calculations. The short-wavelength emission is due to an excited state localized on the pyrylium fragment and the long-wavelength emission arises from a charge-transfer state delocalized over the whole molecule. The two fluorescing states do not exhibit a precursor-successor relationship. The rise time of the short-wavelength fluorescence is smaller than 200 fs, and that of the long-wavelength emission depends on the electron-donating property of the styryl group substituent. The rise is almost prompt with the weaker donors but is slower, wavelength and viscosity dependent with the strongest electron-donating group. A model involving a S(2)/S(1) conical intersection is proposed to account for these observations. 相似文献
983.
Wallace KJ Fagbemi RI Folmer-Andersen FJ Morey J Lynth VM Anslyn EV 《Chemical communications (Cambridge, England)》2006,(37):3886-3888
The detection of chemical warfare simulants is attained by the PET mechanism that gives an "off-on" fluorescent response with a half-life of approximately 50 ms upon phosphorylation of a reactive oximate functionality; the X-ray crystal structure of the oximate was also obtained and is discussed. 相似文献
984.
Cameron TS Decken A Kowalczyk RM McInnes EJ Passmore J Rawson JM Shuvaev KV Thompson LK 《Chemical communications (Cambridge, England)》2006,(21):2277-2279
[ClCNSSS]2(2+) is the first example of a thiazyl radical dimer where population of a thermally excited spin triplet state has been detected, as is proved by VT-powder and single-crystal EPR spectroscopy. 相似文献
985.
Divalent complexes of iron and cobalt with new, monoanionic tripodal amido-polyphosphine ligands have been thoroughly characterized, and XRD analysis reveals geometries that are distinct for this class of ligand. 相似文献
986.
2,4-Difluorotoluene is unusual among hydrofluorocarbons because it is shaped like the DNA base thymine. It was first synthesised as a nucleotide analogue and incorporated into DNA a decade ago. Although it is a nonpolar molecule, it was found to be replicated by DNA polymerase enzymes as if it were thymine. We concluded that replication of DNA base pairs can occur without Watson-Crick hydrogen bonds, and hypothesised that steric effects, rather than these hydrogen bonds, were the main arbiters of DNA replication fidelity. A debate was initiated then, with claims by some that the molecule is polar and forms hydrogen bonds with adenine, thus supporting the hydrogen bonding theory of DNA replication. Here we discuss the evolution of this debate, and reflect on the relevant data that have since come from hundreds of papers and dozens of laboratories. Although discussion on this topic continues, the steric hypothesis for DNA replication is now widely accepted among biochemists, and the changing paradigm has been reflected in textbooks. 相似文献
987.
Lyskawa J Sallé M Balandier JY Le Derf F Levillain E Allain M Viel P Palacin S 《Chemical communications (Cambridge, England)》2006,(21):2233-2235
The formation of the two dimeric species [(TTF)2]+* and (TTF+*)2 can be monitored by complexation of Na+ on a calix[4]arene-TTF assembly. 相似文献
988.
Preat J Jacquemin D Wathelet V André JM Perpète EA 《The journal of physical chemistry. A》2006,110(26):8144-8150
The UV absorption spectra of more than 80 substituted coumarins and chromones have been investigated with the PCM-TD-DFT theoretical scheme using three hybrid functionals (O3LYP, B3LYP, and PBE0) and taking into account methanol or ethanol solvation effects. For most of the studied derivatives, there are at least two allowed excited states presenting a strong oscillator strength in the UV region. The first allowed excitation is associated to a HOMO-LUMO transition whereas the second corresponds to a transition from the HOMO-1 to the LUMO. Both involve a charge transfer from the benzenic cycle to the pyranone moiety. Statistically treating the PBE0 results allows a prediction of the lambda(max) with small standard deviations: in methanol, 6 nm (0.07 eV) for the first excitation (lambda(max)(1)) and 5 nm (0.08 eV) for the second one (lambda(max)(2)), whereas in ethanol 6 nm (0.08 eV) for (lambda(max)(1)) and 6 nm (0.13 eV) for (lambda(max)(2)). 相似文献
989.
Ge N Fogel P Young SS Austin RE Wegrzyniak E Connelly JA 《Combinatorial chemistry & high throughput screening》2006,9(6):465-472
The goal of combinatorial chemistry is to simultaneously synthesize sets of compounds possessing properties that are then distinguished through screening. As the size of a compound set increases, data analysis becomes more challenging. Analysis of Variance (ANOVA) is an accepted statistical method that offers a straightforward solution to this problem. Two steps encountered by combinatorial scientists appear well suited to ANOVA: the prediction of synthetic outcomes (purity and yield) of set members and the analysis of screening data to identify combinations of reagent inputs that result in molecules with a desired property. To illustrate, a subset of a combinatorial array, referred to as a reaction rehearsal set, is evaluated to create a model predictive of the individual synthetic outcomes of the full matrix. In a second exercise, the biochemical screening data obtained from a combinatorial library is analyzed to identify reagent interactions that result in molecules possessing the sought activity. 相似文献
990.