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排序方式: 共有107条查询结果,搜索用时 15 毫秒
41.
Dr. David Teze Dr. Jiao Zhao Mathias Wiemann Dr. Zubaida G. A. Kazi Rossana Lupo Dr. Birgitte Zeuner Dr. Marlène Vuillemin Mette E. Rønne Dr. Göran Carlström Prof. Jens Ø. Duus Dr. Yves-Henri Sanejouand Dr. Michael J. O'Donohue Prof. Eva Nordberg Karlsson Dr. Régis Fauré Prof. Henrik Stålbrand Prof. Birte Svensson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(40):10323-10334
Glycobiology is dogged by the relative scarcity of synthetic, defined oligosaccharides. Enzyme-catalysed glycosylation using glycoside hydrolases is feasible but is hampered by the innate hydrolytic activity of these enzymes. Protein engineering is useful to remedy this, but it usually requires prior structural knowledge of the target enzyme, and/or relies on extensive, time-consuming screening and analysis. Here, a straightforward strategy that involves rational rapid in silico analysis of protein sequences is described. The method pinpoints 6–12 single-mutant candidates to improve transglycosylation yields. Requiring very little prior knowledge of the target enzyme other than its sequence, the method is generic and procures catalysts for the formation of glycosidic bonds involving various d /l -, α/β-pyranosides or furanosides, and exo or endo action. Moreover, mutations validated in one enzyme can be transposed to others, even distantly related enzymes. 相似文献
42.
Micol Santi Jakob Seitz Rossana Cicala Tomas Hardwick Dr. Nisar Ahmed Prof. Dr. Thomas Wirth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16230-16235
Amino acid derivatives undergo non-Kolbe electrolysis to afford enantiomerically enriched α-alkoxyamino derivatives through intermediate chiral carbenium ions. The products contain N,O-acetals which are important structural motifs found in bioactive natural products. The reaction is performed in a continuous flow electrochemical reactor coupled to a 2D-HPLC for immediate online analysis. This allowed a fast screening of temperature, electrode material, current, flow-rate and concentration in a DoE approach. The combination with online HPLC demonstrates that also stereoselective reactions can benefit from a hugely accelerated optimisation by combining flow electrochemistry with multidimensional analysis. 相似文献
43.
The electron spin resonance (ESR) of radicals obtained by electrolytic reduction of 4-[2-(3,4-Dimethoxiphenyl)ethyl]-1-(5-nitrofurfurylidine)semicarbazide and 4-[2-(3,4-Dimethoxyphenyl)ethyl]-1-(5-nitrothienilydene)semicarbazide were measured in DMSO. The electrochemistry of these compounds was studied in DMSO, DMF and ACN using cyclic voltammetry. 相似文献
44.
Elisabetta Alberico Serafino Gladiali Rossana Taras Kathrin Junge Matthias Beller 《Tetrahedron: Asymmetry》2010,21(11-12):1406-1410
Monodentate binaphthophosphepines (BINEPINES) have been tested in the palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenylallyl esters. Stereoselectivities of up to 92% ee have been achieved in the alkylation of the acetate ester with the C-nucleophile, generated in situ by the action of BSA (N,O-bis(trimethylsilyl)acetamide) on dimethylmalonate in the presence of a catalytic amount of sodium acetate. 相似文献
45.
Benfatti F Cardillo G Gentilucci L Perciaccante R Tolomelli A Catapano A 《The Journal of organic chemistry》2006,71(24):9229-9232
Two new classes of azido- and aziridino-hydroxyl-beta-lactam containing structures have been prepared by means of a stereo- and regioselective epoxide ring opening. The straightforwardness of the procedure makes this strategy useful for the synthesis of potentially bioactive compounds. Some selected examples showed promising activity in acyl CoA-cholesterol acyltransferase inhibition assays. 相似文献
46.
47.
Rossana Dell'Anna Roberto Canteri Nicola Coppedè Salvatore Iannotta Massimo Bersani 《Surface and interface analysis : SIA》2013,45(8):1197-1205
The issue of automated peak selection in time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) spectra is examined in relation to the hierarchical nature of the experimental design and the related existence of observations which are not statistically independent. To avoid unreliable results, the presence of pseudoreplication should be taken into account correctly. A combination of the recommended univariate peak selection approach with some multivariate techniques, namely principal component analysis and heat map data representation, is proposed to highlight and analyze obtained results for a set of ToF‐SIMS spectra from copper phthalocyanine thin films grown on TiO2 substrates by a supersonic beam deposition apparatus. New insight is obtained on the effectiveness of the deposition for different working parameters of the process. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
48.
Daniela Nicole Filoni Rossana Pesi Simone Allegrini Marcella Camici Maria Grazia Tozzi 《Analytical and bioanalytical chemistry》2013,405(27):8951-8954
The analysis of the oligomeric active state of a native protein usually requires the application of at least two analytical methods such as gel filtration and analytical ultracentrifugation. Both methods require a substantial amount of protein, time and/or expensive equipment. We here describe a native electrophoretic method for the identification of the native molecular weight of the recombinant wild-type cytosolic 5′-nucleotidase (cN-II) and of its mutants in subunit interfaces Y115A, F36R, K311A and G319Q. The protein was stained both with protein dye and with an activity staining method. Our results demonstrated that purified recombinant protein preparations contained substantial amounts of nucleic acids and misfolded, inactive protein. Furthermore, cN-II mutants K311A and G319Q in subunit interface assume a quaternary dimeric active form, while the only active quaternary structure of wild-type cN-II is the tetramer. 相似文献
49.
Paula Souza Prestes Marlus Chorilli Leila Aparecida Chiavacci Maria Virgínia Scarpa Gislaine Ricci Leonardi 《Journal of Dispersion Science and Technology》2013,34(1):117-123
This article presented physicochemical characterization and rheological behavior evaluation of the liquid crystalline mesophases developed with different silicones. There were prepared 5 ternary systems, which were carried out the determination of the relative density, the electric conductivity and polarized light microscopy analysis, being selected two systems to promote the Preliminary Stability Tests. The results showed that System 1 obtained the major liquid crystal formation and a higher stability. The temperature influences in the systems stability and phases structure. In hot oven, observed oneself the mixture of lamellar and hexagonal phase, for both systems. 相似文献
50.
Transplantation of spermatogonial stem cells (SSCs), the male germline stem cells, in experimental animal models has been successfully used to study mechanisms involved in SSC self-renewal and to restore fertility. However, there are still many challenges associated with understanding the recipient immune response for SSCs use in clinical therapies. Here, we have undertaken a detailed structural study of macrophages elicited by SSCs transplantation in mice using both high-resolution light microscopy (HRLM) and transmission electron microscopy (TEM). We demonstrate that SSCs transplantation elicits a rapid and potent recruitment of macrophages into the seminiferous epithelium (SE). Infiltrating macrophages were derived from differentiation of peritubular monocyte-like cells into typical activated macrophages, which actively migrate through the SE, accumulate in the tubule lumen, and direct phagocytosis of differentiating germ cells and spermatozoa. Quantitative TEM analyses revealed increased formation of lipid bodies (LBs), organelles recognized as intracellular platforms for synthesis of inflammatory mediators and key markers of macrophage activation, within both infiltrating macrophages and Sertoli cells. LBs significantly increased in number and size in parallel to the augmented macrophage migration during different times post-transplantation. Our findings suggest that LBs may be involved with immunomodulatory mechanisms regulating the seminiferous tubule niche after SSC transplantation. 相似文献