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991.
Pan Xue Yongming Li Zhujun Zhang Aihua Fu Fei Liu Xiaoming Zhang Yuanjie Sun Lili Chen Boquan Jin Kun Yang 《Mikrochimica acta》2011,174(1-2):167-174
An enzyme-linked immunosorbent assay, a horseradish peroxidase-catalyzed fluorogenic reaction, and chemiluminescence (CL) analysis have been combined to develop a sandwich ELISA for Staphylococcal enterotoxin B (SEB) using monoclonal antibodies for different epitopes of SEB. The enzyme catalyzed reaction of 3-(4-hydroxyphenyl propionate) with the urea complex of hydrogen peroxide produced a fluorescent dimer which was detected by chemiluminescence analysis. The CL response to SEB is linear in the range from 6.0 to 564?pg?mL?1 (r?=?0.9993), and the detection limit is 3.3?pg?mL?1 (S/N?=?3). Intra- and interassay coefficients of variation are <7.0% at three concentrations (24, 96 and 384?pg?mL?1). The method was applied to the analysis of SEB in serum, lake water and milk samples. The results compared well with those obtained by conventional ELISAs. Figure
Procedures of the proposed method. A sandwich ELISA for Staphylococcal enterotoxin B (SEB) using a pair of monoclonal antibodies that recognizes different epitopes of SEB. After the ELISA procedure, PHPPA is reacted with Hydrogen peroxide-urea, with catalysis by HRP-conjugated anti-SEB, to produce PHPPA fluorescent Dimer, which is detected by TCPO chemiluminescence. 相似文献
992.
993.
以廉价的异香草醛和2,4,6-三羟基苯乙酮为起始原料,经过C-异戊烯基化、选择性甲基化、甲氧甲基化、羟醛缩合、去保护基、催化环化以及脱除甲基等步骤,分别以13.3%和23%的总收率首次完成了天然异戊烯基黄烷酮Glovanon(1)和5-O-methylglovanon(2)的全合成.合成的关键步骤是2,4,6-三羟基苯乙酮的单C-异戊烯基化.所有新化合物的结构都经过1H NMR,IR,MS确认.抑菌活性研究表明,两种新合成的化合物对藤黄微球菌(M.luteus)和大肠杆菌(E.coli)均有良好的抑制作用. 相似文献
994.
995.
Fu H Pang S Xue P Yang J Liu X Wang Y Li T Li H Li X 《Applied biochemistry and biotechnology》2011,165(2):465-475
Fibroblast growth factor-21 (FGF21) is a hepatic hormone that plays a critical role in metabolism, stimulating fatty acid
oxidation in the liver and glucose uptake in adipose tissue. In this study, we produced tobacco plants expressing human recombinant
FGF21 (hFGF21) via Agrobacterium-mediated transformation using a potato virus X (PVX)-based vector (pgR107). The vector contained the sequence encoding the
human FGF21 gene fused with green florescence protein and a histidine tag. The recombinant plasmid was introduced into leaf
cells of Nicotiana benthamiana (a wild Australian tobacco) via Agrobacterium-mediated agroinfiltration. As determined by fluorescence and Western blot of leaf extracts, the hFGF21 gene was correctly
translated in tobacco plants. Seven days after agroinfection, the recombinant hFGF21 had accumulated to levels as high as
450 μg g−1 fresh weight in leaves of agroinfected plants. The recombinant hFGF21 was purified from plant tissues by Ni–NTA affinity
chromatography, and the purified hFGF21 stimulated glucose uptake in 3T3/L1 cells. This indicated that the recombinant hFGF21
expressed via the PVX viral vector in N. benthamiana was biologically active. 相似文献
996.
Marine-derived fungi are prone to produce structurally unique secondary metabolites, a considerable number of which display the promising biological properties and/or industrial applications. Among those, ligninolytic enzymes have attracted great interest in recent years. In this work, about 20 strains were isolated from sea mud samples collected in the East China Sea and then screened for their capacity to produce lignin-degrading enzymes. The results showed that a strain, named J63, had a great potential to secrete a considerable amount of laccase. Using molecular method, it was identified as an endophytic fungus, Pestalotiopsis sp. which was rarely reported as ligninolytic enzyme producer in the literature. The production of laccase by Pestalotiopsis sp. J63 was investigated under submerged fermentation (SF) and solid state fermentation (SSF) with various lignocellulosic by-products as substrates. The SSF of rice straw powder accumulated the highest level of laccase activity (10,700 IU/g substrate), whereas the SF of untreated sugarcane bagasse provided the maximum amount of laccase activity (2,000 IU/ml). The value was far higher than those reported by other reports. In addition, it produced 0.11 U/ml cellulase when alkaline-pretreated sugarcane bagasse was used as growth substrate under SF. Meanwhile, the growth of fungi and laccase production under different salinity conditions were also studied. It appeared to be a moderately halo-tolerant organism. 相似文献
997.
Liu X Xu D Lu R Li B Qian C Xue P Zhang X Zhou H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(5):1660-1669
A series of new triphenylamine-functionalized bis(β-diketone)s bridged by a carbazole (CnBDKC, n=1, 4, 8, 16) with twisted intramolecular charge-transfer emission in polar solvents has been synthesized. The length of the carbon chains has a significant effect on the self-assembling properties of the compounds. Well-defined 1D nanowires were easily generated from C1BDKC with a methyl group by a reprecipitation approach directed by π-stacking interaction, and the molecules packed into J-aggregates in the nanowires. In addition, 1D nanofibers based on C16BDKC bearing a long hexadecyl chain were prepared through the organogelation process, and H-aggregates were formed driven by the synergistic effect of π-stacking interaction and van der Waals force in the gel phase. C4BDKC and C8BDKC containing butyl and octyl side chains, respectively, cannot arrange into dispersed nanostructures, probably because π-π interaction between conjugated moieties might be disturbed by the interaction between the side chains, which is, however, not strong enough to dominate the self-assembling process. Notably, the nanowires based on C1BDKC and the gel nanofibers from C16BDKC can emit strong green light under irradiation, which suggests that these 1D nanomaterials may have potential applications in emitting materials as well as photonic devices. 相似文献
998.
Xue J Wang S You X Dong J Han L Liu F 《Rapid communications in mass spectrometry : RCM》2011,25(21):3289-3297
A sensitive and rapid multi-residue analytical method for plant growth regulators (PGRs) (i.e., chlormequat, mepiquat, paclobutrazol, uniconazole, ethephon and flumetralin) in apples and tomatoes was developed using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A homogenised sample was extracted with a mixture of methanol/water (90:10, v/v) and adjusted to pH <3 with formic acid. Primary secondary amine (PSA) adsorbent was used to clean up the sample. The determination was performed using electrospray ionisation (ESI) and a triple quadrupole (QqQ) analyser. Under the optimised method, the results showed that, except for ethephon, the recoveries were 81.8-98.1% in apples and tomatoes at the spiked concentrations of 0.005 to 2 mg/kg, with relative standard deviations (RSDs) of less than 11.7%. The limits of quantification (LOQs) were lower than their maximum residue limits (MRLs). The procedure was concluded as a practical method to determine the PGR residues in fruit and vegetables and is also suitable for the simultaneous analysis of the amounts of samples for routine monitoring. The analytical method described herein demonstrates a strong potential for its application in the field of PGR multi-residue analysis to help assure food safety. 相似文献
999.
Gold nanoparticles (Au-NPs) with negative charges aggregate in the presence of Arg(6) due to electrostatic interactions resulting in the red-shift of the plasmon absorption. But, after incubation of Arg(6) with trypsin the aggregation of Au-NPs can be prohibited. Accordingly, a newly designed-Au-NPs based colorimetric assay method for trypsin activity is established. Trypsin with a concentration as low as 1.6 ng mL(-1) can be assayed with this new colorimetric assay. This colorimetric label-free assay for trypsin can be performed in aqueous solution and both Au-NPs and Arg(6) are easily accessible. Thus, this assay method is useful for screening inhibitors of trypsin. 相似文献
1000.
A normal-phase enantioselective high-performance liquid chromatographic method was developed for the enantiomeric resolution of naproxcinod, the most advanced cyclooxygenase-inhibiting nitric oxide donator of anti-inflammatory drugs designed for treatment of osteoarthritis. The enantiomers of naproxcinod were resolved on a Chiralpak AD-H (250 × 4.6 mm, 5 μm) column using a mobile phase system containing n-hexane and 2-propanol (95:5, v/v). The resolution between the enantiomers was found to be more than 2.0. The limit of detection and limit of quantitation of (R)-enantiomer were found to be 5 and 15 ng/mL, respectively, for 20 μL injection volume. The sample solution and mobile phase were found to be stable for at least 48 h. The final optimized method was successfully applied to separate (R)-enantiomer from naproxcinod and was proven to be reproducible and accurate for the quantitative determination of (R)-enantiomer in bulk drugs. 相似文献