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排序方式: 共有453条查询结果,搜索用时 31 毫秒
431.
Ettore Benedetti Enrico Gavuzzo Antonello Santini Darin R. Kent Yun-Fei Zhu Qin Zhu Christian Mahr Murray Goodman 《Journal of peptide science》1995,1(6):349-359
The synthesis and X-ray diffraction analysis of two dipeptide taste ligands have been carried out as part of our study of the molecular basis of taste. The compounds L -aspartyl-D -α-methylphenylalanine methyl ester [L -Asp-D -(αMe)Phe-OMe] and L -aspartyl-D -alanyl-2,2,5,5-tetramethylcyclopentanyl ester [L -Asp-D -Ala-OTMCP] elicit bitter and sweet taste, respectively. The C-terminal residues of the two analogues adopt distinctly different conformations in the solid state. The aspartyl moiety assumes the same conformation found in other dipeptide taste ligands with the side-chain carboxylate and the amino groups formaing a zwitterionic ring with a conformation defined by ψ,χX1 = 157.7°, ?61.5° for L -Asp-D -Ala-OTMCP and 151.0°, ?68.8° for L -Asp-D -(αMe)Phe-OMe. In the second residue, a left-handed helical conformations is observed for the (αMe)Phe residue of L -Asp-D -(αMe)Phe-OMe with ?2 = 49.0° and ψ2 = 47.9°, while the Ala residue of L -Asp-D -Ala-OTMCP adopts a semi-exextended conformation characterized by dihedral angles ?2 = 62.8° and ψ2 = ?139.9°. The solid-state structure of the bitter L -Asp-D -(αMe)Phe-OMe is extended; while the crystal structure of the sweet L -Asp-D -OTMCP roughly adopts the typical L-shaped structure shown by other sweeteners. The data of L -Asp-D -(αMe)Phe-OMe are compared with those of its diastereoisomer L -Asp-L -(αMe)Phe-OMe. Conformational analysis of the two taste ligands in solution by NMR and computer simulations agrees well with our model for sweet and bitter tastes. 相似文献
432.
Stefano Mazzoleni Fabrizio Cartenì Giuliano Bonanomi Guido Incerti Maria Luisa Chiusano Pasquale Termolino Antonello Migliozzi Mauro Senatore Francesco Giannino Max Rietkerk Antonio Risitano Virginia Lanzotti 《Phytochemistry Reviews》2014,13(4):937-946
The research for new products against pathogens, parasites and infesting species, in both agriculture and medicine, implies huge and increasing scientific, industrial and economic efforts. Traditional approaches are based on random screening procedures searching for bioactive compounds. However, the success of such methodologies in most cases has been strongly limited by side-effects of the potential new drugs, especially toxicity and pharmacological resistance. The use of nucleic acids in drug development has been introduced searching for target-specific effect. In addition, a recent discovery revealed that randomly fragmented extracellular self-DNA may act as highly species-specific inhibitory product for different species, suggesting an unprecedented use of DNA for biological control. On this base, a new scenario of pharmacological applications is discussed. 相似文献
433.
Fulvio Esposito Anna Maria Santroni Annette Habluetzel Vincenzo Grelloni Antonello Pessi Stefania Lombardi Giancarlo Falcioni Maurizio Brunori 《International journal for parasitology》1990,20(8):1109-1111
The synthetic peptide (NANP)20, reproducing the tandem-repeated epitope of the circumsporozoite protein of Plasmodium (Laverania) falciparum, was entrapped into murine, autologous erythrocytes by a hypotonic dialysis method. Mice immunized intravenously with minute amounts of encapsulated peptide produced considerable antibody titres. This result indicates that intraerythrocytic antigen administration may have a potential as an immunization system for humans, since it dispenses with adjuvants and carrier molecules. 相似文献
434.
435.
436.
Giarita Ferraro Andrea Pica Irene Russo Krauss Francesca Pane Angela Amoresano Antonello Merlino 《Journal of biological inorganic chemistry》2016,21(4):433-442
The products of the reaction between cisplatin (CDDP) and the model protein hen egg white lysozyme (HEWL) at 20, 37 and 55 °C in pure water were studied by UV–Vis absorption spectroscopy, intrinsic fluorescence and circular dichroism, dynamic and electrophoretic light scattering and inductively coupled plasma mass spectrometry. X-ray structures were also solved for the adducts formed at 20 and 55 °C. Data demonstrate that high temperature facilitates the formation of CDDP-HEWL adducts, where Pt atoms bind ND1 atom of His15 or NE2 atom of His15 and NH1 atom of Arg14. Our study suggests that high human body temperature (fever) could increase the rate of drug binding to proteins thus enhancing possible toxic side effects related to CDDP administration. 相似文献
437.
Stem cells are responsible for preserving morphology and function of adult tissues. Stem cells divide to self-renew and to generate progenitor cells to sustain cell demand from the tissue throughout the organism''s life. Unlike stem cells, the progenitor cells have limited proliferation potential but have the capacity to terminally differentiate and thereby to substitute older or damaged mature cells. Recent findings indicate that adult stem cells can adapt their division kinetics dynamically to match changes in tissue demand during homeostasis and regeneration. However, cell turnover not only requires stem cell division but also needs timed differentiation of the progenitor cells, which has been much less explored. In this Extra View article, we discuss the ability of progenitor cells to actively postpone terminal differentiation in the absence of a local demand and how tissue demand activates terminal differentiation via a conserved mesenchymal-epithelial transition program revealed in our recent EMBO J paper and other published and unpublished data. The extent of the significance of these results is discussed for models of tissue dynamics during both homeostasis and regeneration. 相似文献
438.
Angela Sandri Petra R. Basso Ilaria Corridori Marina Protasoni Gabriel Segalla Mario Raspanti Antonello E. Spinelli Federico Boschi 《Journal of biophotonics》2021,14(6):e202000445
Laser scalpels used in medical surgery concentrate light energy, heating the tissues. Recently, we reported thermoluminescence emission from laser-treated soft tissues. Here we investigated the thermo-optical effects caused by a laser operating at 808 nm on animal bones (beef ribs) through luminescence and fluorescence imaging, thermal imaging and scanning electron microscopy. Laser-induced artificial lesions emitted luminescence peaking around 650 nm, with a half-life of almost 1 hour. As concerns fluorescence, 24 hours after laser treatment we observed an increase of the emission and a shift from 500 (untreated) to 580 nm (treated). Recrystallization observed by SEM indicates that the temperature in the artificial lesions is over 600°C. We can conclude that laser treatment induces specific luminescent and fluorescent emissions due to heating of the bone and modification of its components. Monitoring these emissions could help prevent tissue overheating and its potential damages during laser-assisted medical procedures. 相似文献
439.
Fernando Formaggio Marco Crisma Claudio Toniolo Ettore Benedetti Benedetto Di Blasio Michele Saviano Stefania Galdiero John Kamphuis Antonello Santini 《Journal of peptide science》1995,1(6):396-402
The terminally blocked tetrapeptide pBrBz-[D -(αMe)Leu]2-D -(αMe)Val-D -(αMe)Leu-OtBu is folded in the crystal state in a left-handed 310-helical structure stabilized by two consecutive 1 ← 4 C?O ?H? N intramolecular H-bonds, as determined by X-ray diffraction analysis. A CD study strongly supports the view that this conformation is also that largely prevailing in MeOH solution. A comparison with the published conformation of pBrBz-[D -(αMe)Leu]4-OtBu indicates that incorporation of a single internal β-branched (αMe)Val guest residue into the host homo-tetrapeptide from the γ-branched (αMe)Leu residue is responsible for a dramatic structural perturbation, i.e. an inversion of the 310 screw sense from right to left-handed. 相似文献
440.
Franz Oswald Patrick Rodriguez Benedetto Daniele Giaimo Zeus A. Antonello Laura Mira Gerhard Mittler Verena N. Thiel Kelly J. Collins Nassif Tabaja Wiebke Cizelsky Melanie Rothe Susanne J. Kühl Michael Kühl Francesca Ferrante Kerstin Hein Rhett A. Kovall Maria Dominguez Tilman Borggrefe 《Nucleic acids research》2016,44(10):4703-4720