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631.
Chevreux S Llorens I Solari PL Roudeau S Devès G Carmona A Testemale D Hazemann JL Ortega R 《Electrophoresis》2012,33(8):1276-1281
Extended X-ray absorption fine structure (EXAFS) has already provided high-resolution structures of metal-binding sites in a wide variety of metalloproteins. Usually, EXAFS is performed on purified metalloproteins either in solution or crystallized form but purification steps are prone to modify the metallation state of the protein. We developed a protocol to couple EXAFS analysis to metalloprotein separation using native gel electrophoresis. This coupling opens a large field of applications as metalloproteins can be characterized in their native state avoiding purification steps. Using native isoelectric focusing, the method enables the EXAFS analysis of metalloprotein pI isoforms. We applied this methodology to SOD1, wild-type, and Ala4Val mutant (A4V), a mutation found in amyotrophic lateral sclerosis (ALS) because decreased Zn affinity to SOD1 mutants is suggested to be involved in the pathogenesis of this neurodegenerative disease. We observed similar coordination structures for Zn in wild-type and mutant proteins, in all measured pI isoforms, demonstrating the feasibility of EXAFS on electrophoresis gels and suggesting that the Zn-binding site is not structurally modified in A4V SOD1 mutant. 相似文献
632.
Ferreri C Pierotti S Barbieri A Zambonin L Landi L Rasi S Luisi PL Barigelletti F Chatgilialoglu C 《Photochemistry and photobiology》2006,82(1):274-280
Glycerophosphatidylcholine containing trans-unsaturated fatty acid residues was prepared by reaction of the corresponding naturally occurring cis lipid with photochemically generated thiyl radicals. This modified lipid was chosen as the simplest model for gaining some insights of the complex scenario of membrane formation, in connection with the role of lipid geometry and the predominance of cis lipids in eukaryotic cells. The critical aggregation concentration for the spontaneous formation of vesicles was determined for cis and trans isomers with cis-parinaric acid used as a fluorescent probe and it was found to be similar for both lipids. Vesicle dimensions were investigated by light scattering and electron microscopy, and the type of fatty acid residues influenced the vesicle diameter, with a decrease along the series cis > trans > saturated. Fluorescence measurement of dye release from trans and cis vesicles showed also a different permeability. A picture emerged of the geometrical isomer preference in cells as a process driven by natural selection during the life evolution of different organisms, both in terms of compartment dimensions and membrane functionality. 相似文献
633.
Marengo E Robotti E Bobba M Liparota MC Rustichelli C Zamò A Chilosi M Righetti PG 《Electrophoresis》2006,27(2):484-494
Mantle cell lymphoma (MCL) cell lines have been difficult to generate, since only few have been described so far and even fewer have been thoroughly characterized. Among them, there is only one cell line, called GRANTA-519, which is well established and universally adopted for most lymphoma studies. We succeeded in establishing a new MCL cell line, called MAVER-1, from a leukemic MCL, and performed a thorough phenotypical, cytogenetical and molecular characterization of the cell line. In the present report, the phenotypic expression of GRANTA-519 and MAVER-1 cell lines has been compared and evaluated by a proteomic approach, exploiting 2-D map analysis. By univariate statistical analysis (Student's t-test, as commonly used in most commercial software packages), most of the protein spots were found to be identical between the two cell lines. Thirty spots were found to be unique for the GRANTA-519, whereas another 11 polypeptides appeared to be expressed only by the MAVER-1 cell line. A number of these spots could be identified by MS. These data were confirmed and expanded by multivariate statistical tools (principal component analysis and soft-independent model of class analogy) that allowed identification of a larger number of differently expressed spots. Multivariate statistical tools have the advantage of reducing the risk of false positives and of identifying spots that are significantly altered in terms of correlated expression rather than absolute expression values. It is thus suggested that, in future work in differential proteomic profiling, both univariate and multivariate statistical tools should be adopted. 相似文献
634.
The properties of interfacial water on Cl- and H-terminated Si(111) surfaces are investigated using a first-principles approach and characterized by means of energetic analysis combined with hydrogen-bond counting. The interaction of water with both substrates is found to be significantly weak, although bonding with the Cl-terminated Si(111) surface is relatively stronger because of the electrostatic contribution. According to a molecular picture for attributing the hydrophilic/hydrophobic character, both surfaces should be considered hydrophobic, at variance with the interpretation of recent ultrafast electron crystallography experiments, which seems instead to support a hydrophilic nature of the Cl-terminated Si(111) substrate. 相似文献
635.
Losito I Carbonara T Domenica De Bari M Gobbetti M Palmisano F Rizzello CG Zambonin PG 《Rapid communications in mass spectrometry : RCM》2006,20(3):447-455
Electrospray ionization ion trap mass spectrometry (ESI-ITMS) coupled to a two-dimensional liquid chromatographic separation was applied to the identification of peptides in antimicrobial fractions of the aqueous extracts of nine Italian cheese varieties. In particular, the chromatographic fractions collected during a preliminary fast protein liquid chromatography (FPLC) separation on the cheese extracts were assayed for antimicrobial activity towards Lactobacillus sakei A15. Active fractions were subsequently analyzed by reversed-phase high-performance liquid chromatography electrospray ionization sequential mass spectrometry (HPLC/ESI)-ITMSn, with n up to 3. Peptide identification was then performed starting from a conventional proteomics approach based on tandem mass spectrometric (MS/MS) analysis followed by database searching. In many cases this strategy had to be integrated by a careful correlation between spectral information and predicted peptide fragmentation, in order to reach unambiguous identifications. When even this integrated approach failed, MS3 measurements provided decisive information on the amino acid sequence of some peptides, through fragmentation of pendant groups along the peptide chain. As a result, 45 peptides, all arising from hydrolysis of milk caseins, were identified in nine antimicrobial FPLC fractions of aqueous extracts obtained from five of the nine cheese varieties considered. Many of them corresponded to peptides already known to exhibit biological activity. 相似文献
636.
637.
Pier Giorgio Cozzi Prof. Dr. Fides Benfatti Dr. Luca Zoli Dr. 《Angewandte Chemie (International ed. in English)》2009,48(7):1313-1316
Work‐alcoholic! The elusive enantioselective catalytic α‐alkylation of aldehydes, a widely sought transformation, was brought to execution by the use of alcohols capable of forming stabilized carbocations (see scheme, TFA=trifluoroacetic acid).
638.
639.
Francesco Leonetti Pier Vincenzo Petricca 《Annali di Matematica Pura ed Applicata》2014,193(6):1671-1682
We prove local regularity in Lebesgue spaces for weak solutions \(u\) of quasilinear elliptic systems whose off-diagonal coefficients are small when \(|u|\) is large: the faster off-diagonal coefficients decay, the higher integrability of \(u\) becomes. 相似文献
640.
We consider the notion of smallness and its applications to the characterization of isomorphically polyhedral Banach spaces and the existence of different coverings of either the unit sphere or the unit ball of a Banach space. 相似文献