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341.
342.
James T. HodgkinsonWarren R.J.D. Galloway Mariangela CasoliHarriet Keane Xianbin SuGeorge P.C. Salmond Martin WelchDavid R. Spring 《Tetrahedron letters》2011,52(26):3291-3294
The ready availability of native quorum sensing molecules and related structural analogues is of significant biological interest in the development of methods to manipulate bacterial quorum sensing systems in a useful fashion. In this Letter we report robust routes for the synthesis of a range of N-acylated-l-homoserine lactone (AHL) quorum sensing molecules. Crucially, we have analysed the enantiopurity of the final AHLs and in all cases, excellent levels were observed. 相似文献
343.
McAllister LA Bechle BM Dounay AB Evrard E Gan X Ghosh S Kim JY Parikh VD Tuttle JB Verhoest PR 《The Journal of organic chemistry》2011,76(9):3484-3497
We describe a generalized approach to stereocontrolled synthesis of substituted cyclic hydroxamic acids (3-amino-1-hydroxy-3,4-dihydroquinolinones) by selective reduction of substituted 2-nitrophenylalanine substrates. Compounds in this series have antibacterial properties and have also recently been reported as KAT II inhibitors. The key nitrophenyl alanine intermediates are prepared enantioselectively in excellent yield by phase transfer catalyzed alkylation of the corresponding nitrobenzyl bromides. The scope and limitations of the reductive cyclization transformation have been explored with attention to the effects of substitution pattern and electronics on reaction efficiency and byproduct formation. In addition, a novel activated trifluoroethyl ester cyclization strategy has been developed as an alternate approach to the most sterically demanding systems in this series. 相似文献
344.
Jennifer A. Jamison Erika L. Bryant Shyam B. Kadali Michael S. Wong Vicki L. Colvin Kathleen S. Matthews Michelle K. Calabretta 《Journal of nanoparticle research》2011,13(2):625-636
Gold nanoparticles (AuNP) can interact with a wide range of molecules including proteins. Whereas significant attention has
focused on modifying the nanoparticle surface to regulate protein–AuNP assembly or influence the formation of the protein
“corona,” modification of the protein surface as a mechanism to modulate protein–AuNP interaction has been less explored.
Here, we examine this possibility utilizing three small globular proteins—lysozyme with high isoelectric point (pI) and established
interactions with AuNP; α-lactalbumin with similar tertiary fold to lysozyme but low pI; and myoglobin with a different globular
fold and an intermediate pI. We first chemically modified these proteins to alter their charged surface functionalities, and
thereby shift protein pI, and then applied multiple methods to assess protein–AuNP assembly. At pH values lower than the anticipated
pI of the modified protein, AuNP exposure elicits changes in the optical absorbance of the protein–NP solutions and other
properties due to aggregate formation. Above the expected pI, however, protein–AuNP interaction is minimal, and both components
remain isolated, presumably because both species are negatively charged. These data demonstrate that protein modification
provides a powerful tool for modulating whether nanoparticle–protein interactions result in material aggregation. The results
also underscore that naturally occurring protein modifications found in vivo may be critical in defining nanoparticle–protein
corona compositions. 相似文献
345.
Motivated in part by Eardley et al. (Commun Math Phys 106(1):137–158, 1986), in this note we obtain a rigidity result for globally hyperbolic vacuum spacetimes in arbitrary dimension that admit a timelike conformal Killing vector field. Specifically, we show that if M is a Ricci flat, timelike geodesically complete spacetime with compact Cauchy surfaces that admits a timelike conformal Killing field X, then M must split as a metric product, and X must be Killing. This gives a partial proof of the Bartnik splitting conjecture in the vacuum setting. 相似文献
346.
Robert Galloway Francis J. O'Farell und J. Walter 《Fresenius' Journal of Analytical Chemistry》1887,26(1):342-343
Ohne Zusammenfassung 相似文献
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348.