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61.
Marshall AT Haverkamp RG Davies CE Parsons JG Gardea-Torresdey JL van Agterveld D 《International journal of phytoremediation》2007,9(3):197-206
Enzymatic digestion is proposed as a method for concentrating gold nanoparticles produced in plants. The mild conditions of digestion are used in order to avoid an increase in the gold particle size, which would occur with a high-temperature process, so that material suitable for catalysis may be produced. Gold nanoparticles of a 5-50-nm diameter, as revealed by transmission electron microscopy (TEM), at concentrations 760 and 1120 ppm Au, were produced within Brassica juncea grown on soil with 22-48 mg Au kg(-1). X-ray absorption near edge spectroscopy (XANES) reveals that the plant contained approximately equal quantities of Au in the metallic (Au0) and oxidized (Au+1) states. Enzymatic digestion dissolved 55-60 wt% of the plant matter. Due to the loss of the soluble gold fraction, no significant increase in the total concentration of gold in the samples was observed. However, it is likely that the concentration of the gold nanoparticles increased by a factor of two. To obtain a gold concentration suitable for catalytic reactions, around 95 wt% of the starting dry biomass would need to be solubilized or removed, which has not yet been achieved. 相似文献
62.
Topalis D Kumamoto H Alexandre JA Dugué L Pochet S Berteina-Raboin S Agrofoglio LA Deville-Bonne D 《Nucleosides, nucleotides & nucleic acids》2007,26(10-12):1369-1373
Human UMP-CMP kinase is involved in the phosphorylation of nucleic acid precursors and also in the activation of antiviral analogues including cidofovir, an acyclic phosphonate compound that mimicks dCMP and shows a broad antiviral spectrum. The binding of ligands to the enzyme was here investigated using a fluorescent probe and a competitive titration assay. At the acceptor site, the enzyme was found to accommodate any base, purine and pyrimidine, including thymidine. A method for screening analogues based on their affinity for the UMP binding site was developed. The affinities of uracil vinylphosphonate derivatives modified in the 5 position were found similar to (d)UMP and (d)CMP and improved when compared to cidofovir. 相似文献
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Broggi J Joubert N Aucagne V Berteina-Raboin S Diez-Gonzalez S Nolan S Topalis D Deville-Bonne D Balzarini J Neyts J Andrei G Snoeck R Agrofoglio LA 《Nucleosides, nucleotides & nucleic acids》2007,26(10-12):1391-1394
Hitherto unknown 1,4-disubstituted-[1,2,3]-triazolo-4',4'-dihydroxymethyl-3'-deoxy carbanucleosides were synthesized based on a "click approach." Various alkynes were introduced on a key azido intermediate by the "click" 1,3-dipolar Huisgen cycloaddition. Their antiviral activities and cellular toxicities were evaluated on vaccinia virus. None of the synthesized compounds exhibited a significant antiviral activity. 相似文献
64.
Roy V Kumamoto H Berteina-Raboin S Nolan SP Topalis D Deville-Bonne D Balzarini J Neyts J Andrei G Snoeck R Agrofoglio LA 《Nucleosides, nucleotides & nucleic acids》2007,26(10-12):1399-1402
With the commercial availability of well-defined ruthenium metathesis catalysts which combine high stability and broad functional group compatibility, olefin metathesis is now routinely integrated in various syntheses. We will report here the overwhelming power and scope of cross-metathesis in the area of new acyclic nucleoside phosphonates. Scope and limitations of this approach, and especially the E/Z stereocontrol, are discussed on selected examples from our drug discovery group. 相似文献
65.
Diversification of sterol methyltransferase enzymes in plants and a role for β‐sitosterol in oriented cell plate formation and polarized growth 下载免费PDF全文
Masatoshi Nakamoto Anne‐Catherine Schmit Dimitri Heintz Hubert Schaller Daisaku Ohta 《The Plant journal : for cell and molecular biology》2015,84(5):860-874
Phytosterols are classified into C24‐ethylsterols and C24‐methylsterols according to the different C24‐alkylation levels conferred by two types of sterol methyltransferases (SMTs). The first type of SMT (SMT1) is widely conserved, whereas the second type (SMT2) has diverged in charophytes and land plants. The Arabidopsis smt2 smt3 mutant is defective in the SMT2 step, leading to deficiency in C24‐ethylsterols while the C24‐methylsterol pathway is unchanged. smt2 smt3 plants exhibit severe dwarfism and abnormal development throughout their life cycle, with irregular cell division followed by collapsed cell files. Preprophase bands are occasionally formed in perpendicular directions in adjacent cells, and abnormal phragmoplasts with mislocalized KNOLLE syntaxin and tubulin are observed. Defects in auxin‐dependent processes are exemplified by mislocalizations of the PIN2 auxin efflux carrier due to disrupted cell division and failure to distribute PIN2 asymmetrically after cytokinesis. Although endocytosis of PIN2–GFP from the plasma membrane (PM) is apparently unaffected in smt2 smt3, strong inhibition of the endocytic recycling is associated with a remarkable reduction in the level of PIN2–GFP on the PM. Aberrant localization of the cytoplasmic linker associated protein (CLASP) and microtubules is implicated in the disrupted endocytic recycling in smt2 smt3. Exogenous C24‐ethylsterols partially recover lateral root development and auxin distribution in smt2 smt3 roots. These results indicate that C24‐ethylsterols play a crucial role in division plane determination, directional auxin transport, and polar growth. It is proposed that the divergence of SMT2 genes together with the ability to produce C24‐ethylsterols were critical events to achieve polarized growth in the plant lineage. 相似文献
66.
Symbiodinium transcriptome and global responses of cells to immediate changes in light intensity when grown under autotrophic or mixotrophic conditions 下载免费PDF全文
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Thomas?Durand Sophie?Jacob Laura?Lebouil Hassen?Douzane Philippe?Lestaevel Amithys?Rahimian Dimitri?Psimaras Lo?c?Feuvret Delphine?Leclercq Bruno?Brochet Radia?Tamarat Fabien?Milliat Marc?Benderitter Nicolas?Vayatis Georges?No?l Khê?Hoang-Xuan Jean-Yves?Delattre Damien?Ricard Marie-Odile?BernierEmail author 《BMC neurology》2015,15(1):261