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161.
A considerable problem in proteomics is to separate and identify functional proteins that participate in specific biological processes. To expedite the analysis of active proteases, we have developed a substrate-specific, sensitive in-gel trypsin activity assay after two-dimensional (2-D) separation in a sodium dodecyl sulphate (SDS)-polyacrylamide gel [22]. Using this method, we detected and characterized Arg-specific protease activity in the secreted protein sample of a prostate cancer cell line, PC-3, in 1-D and 2-D gels. Mass spectrometry (MS) identified the protease as urokinase-type plasminogen activator (uPA). Western blotting using anti-uPA antibody and protease inhibition tests confirmed the identification. Since no antibody was involved in the procedure, the result clearly demonstrates the feasibility of this method for identifying novel proteases in biological samples. 相似文献
162.
Alain Turck Nelly Pl Pamla Pollet Guy Quguiner 《Journal of heterocyclic chemistry》1998,35(2):429-436
In the pyridazine series, the use of tert-butylsulfinyl and tert-butylsulfonyl as ortho directing groups for metalation has been tested. Various functionalized products were obtained in good yields. In the case of 3-tert-butylsulfinyl-6-methoxypyridazine, the metalation was regioselective in ortho to the sulfinyl group. The metalation of 2-tert-butylsulfinyl and 2-tert-butylsulfonylpyrazine gave low to moderate yields. Synthesis of diazinesulfonamides were improved and the metalation of N-tert-butylsulfonamidopyrazine was achieved. 相似文献
163.
Pamela J. Davy 《Probability Theory and Related Fields》1984,68(2):243-246
Summary A conjecture concerning the maximum mean secant length through a convex body of fixed volume in
n
is verified, and other moment inequalities are established using a symmetrisation argument. 相似文献
164.
Catherine Lapierre Brigitte Pollet Christian Rolando 《Research on Chemical Intermediates》1995,21(3-5):397-412
Lignins are composed of phenylpropane units interconnected by labile and resistant bonds. A two-step degradation, thioacidolysis, provides detailed information on these network polymers. The first step involves lignin depolymerization with ethanethiol and BF3 etherate. The determination of the recovered thioethylated monomers provides an estimation of lignin units only involved in labile ether bonds. The ligninderived dimers, representative of resistant interunit bonds, are determined after a further desulfurization step. Results obtained for native and industrial hardwood lignins underline their structural differences. Native hardwood lignins are typified by a high proportion of linear fragments linked bifunctionally by β-O-4 bonds. 相似文献
165.
Alain Turck Nelly Pl Pamla Pollet Ljubica Mojovic Jack Duflos Guy Quguiner 《Journal of heterocyclic chemistry》1997,34(2):621-627
The metalation of thioethers, methyl and phenyl sulfoxides and sulfones of pyrazine and pyridazine has been performed. Methyl sulfoxides and sulfones were first metalated on the methyl group. The ortho directing effect of thioethers, sulfoxides and sulfones have been compared with the methoxy group. The sulfoxides were shown to be very good ortho directing groups. 相似文献
166.
Anthony D. Patrick Pamela Williams Estela Blaisten-Barojas 《Journal of Molecular Structure》2007,824(1-3):39-47
Small carbon clusters C, C2 and C3 metallized with beryllium were studied by first principles within the hybrid density functional approach with generalized gradient correction. Cluster isomer structures for the ground state and several excited states where systematically calculated for CxBey with x = 1–3 and y = 1–4 including the vibrational analysis of all states. Ionization potentials and electron affinities are calculated for the ground state cluster isomers. The thermal stability of the ground state isomers was verified within the harmonic approximation of the Helmholtz free energy up to temperatures of about 1000 K. Within the family of clusters studied, C2Be3 undergoes a solid-like structural transition at about 260 K changing from a planar structure at low temperatures to a linear isomer at high temperatures. 相似文献
167.
Michael C Breadmore Sushil Shrinivasan James Karlinsey Jerome P Ferrance Pamela M Norris James P Landers 《Electrophoresis》2003,24(7-8):1261-1270
The potential for using polyelectrolyte multilayers (PEMs) to provide chromatographic functionality on continuous silica networks created from sol-gel chemistry has been evaluated by capillary electrochromatography (CEC). Construction of the PEM was achieved by flushing the column with polyelectrolytes of alternative charge, with variation of the properties of the exposed polyelectrolyte providing a unique means to vary the chromatographic surface. Variation of the exposed polyelectrolyte from poly(diallyldimethylammonium chloride) (PDDAC) to dextran sulfate (DS) allowed the direction of the electroosmotic flow (EOF) to be changed and also provided a means to vary the chromatographic capacity. Variation of negative polymer from DS to poly(styrene sulfonate) (PSS) significantly altered the EOF and the migration of peptides, with both the reversed-phase and ion-exchange capacities increasing. An alternative method for changing the column capacity was to change the thickness of the PEM, which was evaluated by anion-exchange CEC. A 70-80% increase in retention was observed for all anions without any increase in EOF suggesting significant penetration of the analytes through the PEM and interaction with buried charges within the PEM. 相似文献
168.
Cappitelli F Vicini S Piaggio P Abbruscato P Princi E Casadevall A Nosanchuk JD Zanardini E 《Macromolecular bioscience》2005,5(1):49-57
The deterioration of synthetic polymers caused by biological process is usually evaluated by visual inspection and measuring physical effects. In contrast to this approach, we have applied vibrational spectroscopies to study the biodegradation of the synthetic resins. 29 synthetic resins used as paint binding media, including acrylic, alkyd and poly(vinyl acetate) polymers, were examined for potential susceptibility to fungal degradation using the standard method ASTM G21-96(2002). In addition, the degraded resins were analysed by Raman spectroscopy, FT-IR and FT-IR photoacoustic spectroscopy. Almost all the acrylic resins studied proved to be resistant to microbial attack, while all alkyd resins and some poly(vinyl acetates) turned out to be biodegradable. Within a few days of inoculation Aspergillus niger was the most copious fungus on the biodegraded resins. A comparison of the IR and Raman spectra of control and biodegraded resins did not show any differences, but photoacoustic spectroscopy revealed additional bands for the fungal-degraded resins, consistent with the presence of fungal-derived substances. The additional bands in the photoacoustic spectra were due to the presence of Aspergillus niger and melanin, a fungal pigment. Since IR photoacoustic spectroscopy can be also a suitable technique for the chemical characterisation of binding media, the same spectroscopic analysis can be employed to both characterise the material and obtain evidence for fungal colonization. Microbial growth on Sobral 1241ML (alkyd resin) after 28 d (growth rating 4) compared with the non-inoculated resin. 相似文献
169.
170.