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991.
Yan-Yan Wang Fang-Zhou Xu Yun-Ying Zhu Baoan Song Dexia Luo Gang Yu Shunhong Chen Wei Xue Jian Wu 《Bioorganic & medicinal chemistry letters》2018,28(17):2979-2984
A series of pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base moiety were synthesized, characterised, and evaluated for their activity against tobacco mosaic virus (TMV). Biological assays indicated that several of the derivatives exhibited significant activity against TMV. In particularly, compounds 5y and 5aa displayed excellent inactivating activity against TMV, with half maximal effective concentration (EC50) values of 70.3 and 53.65?μg/mL, respectively, which were much better than that of ribavirin (150.45?μg/mL), and 5aa was superior to ningnanmycin (EC50?=?55.35?μg/mL). Interactions of compounds 5y and 5aa with TMV coat protein (TMV-CP) were investigated using microscale thermophoresis and molecular docking. Compounds 5y and 5aa displayed strong binding capability to TMV-CP with dissociation constant (Kd) values of 22.6 and 9.8?μM, respectively. These findings indicate that pyrazolo[3,4-d]pyrimidine derivatives containing a Schiff base may be potential antiviral agents. 相似文献
992.
993.
Application of statistically-based experimental designs for the optimization of eicosapentaenoic acid production by the diatom Nitzschia laevis 总被引:2,自引:0,他引:2
Statistically based experimental designs were applied to the optimization of medium components and environmental factors for eicosapentaenoic acid (EPA) production by the diatom Nitzschia laevis in heterotrophic conditions. First, the Plackett-Burman design was used to evaluate the effects of variables including medium components and environmental factors on cell growth and EPA production. Among these variables, NaCl, CaCl(2), PI metal solution, pH, and temperature were identified to have the significant effects (with confidence level > 90 %). Subsequently, the concentrations of NaCl, CaCl(2), PI metal solution as well as the values of pH and temperature were optimized using central composite design. The cell growth and EPA production were found to respectively correlate to NaCl, CaCl(2), pH, and temperature that could be represented by second-order polynomial models. The optimal values of the four parameters were determined by response surface and numerical analyses as 8 g/L NaCl, 0.10 g/L CaCl(2), pH 8.5 and 19.8 degrees C for cell dry weight (DW), and 14 g/L NaCl, 0.10 g/L CaCl(2), pH 8.5 and 18 degrees C for EPA production, respectively. The subsequent verification experiments confirmed the validity of the models. This optimization strategy led to a DW of 9 g/L, an EPA yield of 280 mg/L and an EPA productivity of 28 mg/L/d, respectively, which were considerably higher than those obtained in the previous studies. 相似文献
994.
Gene 4 of bacteriophage T7 encodes a protein (gp4) that can translocate along single-stranded DNA, couple the unwinding of duplex DNA with the hydrolysis of dTTP, and catalyze the synthesis of short RNA oligoribonucleotides for use as primers by T7 DNA polymerase. Electron microscopic studies have shown that gp4 forms hexameric rings, and X-ray crystal structures of the gp4 helicase domain and of the highly homologous RNA polymerase domain of Escherichia coli DnaG have been determined. Earlier biochemical studies have shown that when single-stranded DNA is bound to the hexameric ring, the primase domain remains accessible to free DNA. Given these results, a model was suggested in which the primase active site in the gp4 hexamer is located on the outside of the hexameric ring. We have used electron microscopy and single-particle image analysis to examine T7 gp4, and have determined that the primase active site is located on the outside of the hexameric ring, and therefore provide direct structural support for this model. 相似文献
995.
996.
我们检测10例普通猪的胄组织,有8例分离到螺杆菌样细菌(HLO)。其菌落、菌体形态和某些生化反应与幽门螺杆菌(HP)相似,但其尿素酶活性较低,HLO全菌蛋白的SDS一pAGE图谱也与HP的不同。本文就HP和HLO及其伴发的人、猪慢性胃炎的特点,作了比较和讨论。 相似文献
997.
离子型谷氨酸受体(iGLuR)是哺乳动物中一类由L-氨基酸(如谷氨酸、甘氨酸)等配体门控的阳离子通道, 具有调节兴奋性神经信号传递和引导神经元发育等分子功能。1998年研究者在拟南芥(Arabidopsis thaliana)中发现了20个与iGLuRs同源的序列(即AtGLRs), 它们的功能涉及植物光信号传递、根尖分生细胞活性、花粉管生长、胞质Ca2+流以及应答多种生物和非生物环境胁迫等。该文从谷氨酸受体(GLR)的结构特征、离子通道激活与配体的关系、表达模式及可能的生物学功能等方面, 综述了近十几年来关于植物GLR和氨基酸信号的研究成果, 旨在为相关领域的同行提供有益的参考。 相似文献
998.
LC-MS/MS determination of helicid in human plasma and its application in pharmacokinetic studies 总被引:1,自引:0,他引:1
Xie H Jia Y Tan Z Zhang W Chen R Sun H Shen J Zhou H 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(30):3607-3611
Helicid is a traditional Chinese medicine used to treat headache and insomnia with definite effects. To facilitate pharmacokinetic studies of helicid in man, a sensitive and specific LC-MS/MS method for the quantitative detection of helicid in human plasma was developed and validated. The method involved the addition of bergeninum as the internal standard (IS), protein precipitation, HPLC separation, and quantification by MS/MS system using negative electrospray ionization in the multiple reaction monitoring mode (MRM). The precursor→product ion transitions were monitored at m/z 282.8→120.9 for helicid and m/z 326.9→192.2 for the IS, respectively. The lower limit of quantification (LLOQ) was 0.2 μg/L. The calibration curves for helicid was linear over a concentration range of 0.2-20 μg/L. The intra- and inter-batch analyses of QC samples at 0.4, 2, 20 μg/L indicated good precision (%R.S.D. between 2.69 and 5.47%) and accuracy (between 96.15 and 105.05%). The helicid was stable in human plasma stored at room temperature for at least 24h, 4°C for at least 24h, -20°C for at least 1 month, and for routine three freeze-thaw cycles. This accurate and specific assay provides a useful method for evaluating the pharmacokinetic profile of helicid in humans. 相似文献
999.
High level expression of axe1, a gene previously cloned from Volvariella volvacea that encodes an acetyl xylan esterase with two potential N-linked glycosylation sites, has been achieved in Pichia pastoris using a codon-optimized axe1 synthesized by the primer extension PCR procedure. The GC content of the codon-optimized axe1 was 48.62% compared with 55.49% in the native gene. Using the codon-optimized construct, AXE1 expression in P. pastoris was increased from an undetectable level to 136.45U/ml six days after induction of yeast cultures grown in BMMY medium. A further increase (to 463U/ml) was achieved when conditions for yeast culture were optimized as follows: 2.8% methanol, 0.63% casamino acids, and pH 8.0. This latter value represented a 3.4-fold and 246-fold increase in the enzyme levels recorded in non-optimized P. pastoris cultures and in rice straw-grown cultures of V. volvacea, respectively. N-linked glycosylation played an essential role in AXE1 secretion but had only a slight effect on the catalytic activity and stability of the recombinant enzyme. 相似文献
1000.