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101.
Divanery Rodriguez-Gomez Linda Lehmann Nadja Schultz-Jensen Anne Belinda Bjerre Timothy John Hobley 《Applied biochemistry and biotechnology》2012,166(8):2051-2063
Plasma-assisted pretreated wheat straw was investigated for cellulase and xylanase production by Trichoderma reesei fermentation. Fermentations were conducted with media containing washed and unwashed plasma-assisted pretreated wheat straw
as carbon source which was sterilized by autoclavation. To account for any effects of autoclavation, a comparison was made
with unsterilized media containing antibiotics. It was found that unsterilized washed plasma-assisted pretreated wheat straw
(which contained antibiotics) was best suited for the production of xylanases (110 IU ml−1) and cellulases (0.5 filter paper units (FPU) ml−1). Addition of Avicel boosted enzyme titers with the highest cellulase titers (1.5 FPU ml−1) found with addition of 50 % w/w Avicel and with the highest xylanase production (350 IU ml−1) reached in the presence of 10 % w/w Avicel. Comparison with enzyme titers from other nonrefined feedstocks suggests that plasma pretreated wheat straw is a promising
and suitable substrate for cellulase and hemicellulase production. 相似文献
102.
Reynolds M Marradi M Imberty A Penadés S Pérez S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4264-4273
Multivalent protein-carbohydrate interactions are involved in the initial stages of many fundamental biological and pathological processes through lectin-carbohydrate binding. The design of high affinity ligands is therefore necessary to study, inhibit and control the processes governed through carbohydrate recognition by their lectin receptors. Carbohydrate-functionalised gold nanoclusters (glyconanoparticles, GNPs) show promising potential as multivalent tools for studies in fundamental glycobiology research as well as biomedical applications. Here we present the synthesis and characterisation of galactose functionalised GNPs and their effectiveness as binding partners for PA-IL lectin from Pseudomonas aeruginosa. Interactions were evaluated by hemagglutination inhibition (HIA), surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) assays. Results show that the gold nanoparticle platform displays a significant cluster glycoside effect for presenting carbohydrate ligands with almost a 3000-fold increase in binding compared with a monovalent reference probe in free solution. The most effective GNP exhibited a dissociation constant (K(d)) of 50 nM per monosaccharide, the most effective ligand of PA-IL measured to date; another demonstration of the potential of glyco-nanotechnology towards multivalent tools and potent anti-adhesives for the prevention of pathogen invasion. The influence of ligand presentation density on their recognition by protein receptors is also demonstrated. 相似文献
103.
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105.
Zagdoun A Casano G Ouari O Lapadula G Rossini AJ Lelli M Baffert M Gajan D Veyre L Maas WE Rosay M Weber RT Thieuleux C Coperet C Lesage A Tordo P Emsley L 《Journal of the American Chemical Society》2012,134(4):2284-2291
A new nitroxide-based biradical having a long electron spin-lattice relaxation time (T(1e)) has been developed as an exogenous polarization source for DNP solid-state NMR experiments. The performance of this new biradical is demonstrated on hybrid silica-based mesostructured materials impregnated with 1,1,2,2-tetrachloroethane radical containing solutions, as well as in frozen bulk solutions, yielding DNP enhancement factors (ε) of over 100 at a magnetic field of 9.4 T and sample temperatures of ~100 K. The effects of radical concentration on the DNP enhancement factors and on the overall sensitivity enhancements (Σ(?)) are reported. The relatively high DNP efficiency of the biradical is attributed to an increased T(1e), which enables more effective saturation of the electron resonance. This new biradical is shown to outperform the polarizing agents used so far in DNP surface-enhanced NMR spectroscopy of materials, yielding a 113-fold increase in overall sensitivity for silicon-29 CPMAS spectra as compared to conventional NMR experiments at room temperature. This results in a reduction in experimental times by a factor >12,700, making the acquisition of (13)C and (15)N one- and two-dimensional NMR spectra at natural isotopic abundance rapid (hours). It has been used here to monitor a series of chemical reactions carried out on the surface functionalities of a hybrid organic-silica material. 相似文献
106.
Jahn S Lohmann W Bomke S Baumann A Karst U 《Analytical and bioanalytical chemistry》2012,402(1):461-471
In the present study, a method for the analysis of reactive metabolites via liquid chromatography (LC) with inductively coupled
plasma–mass spectrometry (MS) was developed. A ferrocenyl-modified glutathione (GSH) reagent, consisting of GSH and succinimidyl-3-ferrocenylpropionate,
was synthesized. Derivatization of the tripeptide was performed at the N-terminus, leaving the nucleophilic thiol group vacant
for the attack of electrophilic compounds. The potential of ferrocenylpropionate (FP)-GSH as a trapping agent for reactive
metabolites was investigated using an electrochemical flow-through cell for metabolism simulation coupled online to a LC system
with electrospray ionization mass spectrometric detection. The pharmaceuticals amodiaquine, an antimalarial agent, and clozapine,
an antipsychotic compound, served as model substances. By proving the successful adduct formation between the reactive metabolite
and ferrocene-labeled GSH, it could be shown that FP-GSH is an effective trapping agent which eases routine reversed-phase
LC analyses. In contrast to GSH, which is usually used for the conjugation of reactive metabolites and where the resulting
adducts often show no or only very little retention, FP-GSH facilitates the detection of the corresponding metabolite adducts
due to higher retention times. 相似文献
107.
Miller EM Sheps L Lu YJ Case AS McCoy AB Lineberger WC 《The Journal of chemical physics》2012,136(4):044313
Negative-ion photoelectron spectroscopy of ICN(-) (X??(2)Σ(+)) reveals transitions to the ground electronic state (X??(1)Σ(+)) of ICN as well as the first five excited states ((3)Π(2), (3)Π(1), Π(0(-) ) (3), Π(0(+) ) (3), and (1)Π(1)) that make up the ICN A continuum. By starting from the equilibrium geometry of the anion, photoelectron spectroscopy characterizes the electronic structure of ICN at an elongated I-C bond length of 2.65 A?. Because of this bond elongation, the lowest three excited states of ICN ((3)Π(2), (3)Π(1), and Π(0(-) ) (3)) are resolved for the first time in the photoelectron spectrum. In addition, the spectrum has a structured peak that arises from the frequently studied conical intersection between the Π(0(+) ) (3) and (1)Π(1) states. The assignment of the spectrum is aided by MR-SO-CISD calculations of the potential energy surfaces for the anion and neutral ICN electronic states, along with calculations of the vibrational levels supported by these states. Through thermochemical cycles involving spectrally narrow transitions to the excited states of ICN, we determine the electron affinity, EA(ICN), to be 1.34(5) (+0.04∕-0.02) eV and the anion dissociation energy, D(0)(X??(2)Σ(+) I-CN(-)), to be 0.83 (+0.04/-0.02) eV. 相似文献
108.
Using a Cu(II) 2-quinoxalinol salen complex as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant, allylic activations of olefin substrates can be converted to the corresponding enones or 1,4-enediones. Excellent yields can be achieved (up to 99%) within a very short reaction time and with great tolerance for additional functional groups. Possible mechanistic pathways have been characterized using Raman spectroscopy, cyclic voltammetry, and theoretical calculations. 相似文献
109.
Kerber RN Kermagoret A Callens E Florian P Massiot D Lesage A Copéret C Delbecq F Rozanska X Sautet P 《Journal of the American Chemical Society》2012,134(15):6767-6775
The determination of the nature and structure of surface sites after chemical modification of large surface area oxides such as silica is a key point for many applications and challenging from a spectroscopic point of view. This has been, for instance, a long-standing problem for silica reacted with alkylaluminum compounds, a system typically studied as a model for a supported methylaluminoxane and aluminum cocatalyst. While (27)Al solid-state NMR spectroscopy would be a method of choice, it has been difficult to apply this technique because of large quadrupolar broadenings. Here, from a combined use of the highest stable field NMR instruments (17.6, 20.0, and 23.5 T) and ultrafast magic angle spinning (>60 kHz), high-quality spectra were obtained, allowing isotropic chemical shifts, quadrupolar couplings, and asymmetric parameters to be extracted. Combined with first-principles calculations, these NMR signatures were then assigned to actual structures of surface aluminum sites. For silica (here SBA-15) reacted with triethylaluminum, the surface sites are in fact mainly dinuclear Al species, grafted on the silica surface via either two terminal or two bridging siloxy ligands. Tetrahedral sites, resulting from the incorporation of Al inside the silica matrix, are also seen as minor species. No evidence for putative tri-coordinated Al atoms has been found. 相似文献
110.