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961.
The combination of a circular dichroism detector and nonchiral liquid chromatography was used for the chiral analysis of unresolved enantiomers to determine the enantioselectivity of a molybdenum-catalyzed asymmetric allylic alkylation reaction. The CD/UV peak area ratio of the unresolved enantiomers was calculated and compared with that of a reference standard to determine the enantiomeric purity. The limit of quantitation (LOQ) is 20 ng for the chiral ligand and 1 microg for the branched chiral product. The viability of the system depends on the limit of quantitation of the CD response and the linearity range of the CD and UV response. 相似文献
962.
Ji CN Cai ZL Cao GT Yin G Jiao BH Jiang T Shu G Mao JF Xie Y Mao YM 《Protein and peptide letters》2002,9(6):553-556
Human augmenter of liver regeneration has been expressed in Escherichia coli, purified and crystallized. The crystals belong to space group C222, with unit-cell parameters a=51.7 A, b=78.8 A, c=63.7 A. Diffraction data were collected to 2.80 A with a completeness of 99.9% (99.9% for the last shell), a R(sym) value of 0.092(0.236) and an I/sigma(I) value of 6.2(2.7). 相似文献
963.
964.
Mou QY Chen J Zhu YC Zhou DH Chi ZQ Long YQ 《Bioorganic & medicinal chemistry letters》2002,12(17):2287-2290
A series of 2-(substituted phenyl)-N-methyl-N-[(1S)-1-(substituted alkyl)-2-(1-(3-pyrrolinyl))ethyl]acetamides were synthesized and evaluated as highly selective kappa-agonists with K(i) values in low nanomolar range. 3-Pyrroline incorporated into the basic amino functionality in combination with 2-(methylthio)ethyl substituent on the carbon adjacent to the amide nitrogen remarkably enhanced the kappa-selectivity. 3,4-Dichlorophenyl derivative 1e was found the most potent and selective analgesic in this series with ED(50) value of 0.023 mg/kg. 相似文献
965.
Cheng H Ma Y Ni X Jiang M Guo L Ying K Xie Y Mao Y 《Cytogenetic and genome research》2002,97(1-2):72-75
Rab proteins are small-molecular-weight GTPases that control vesicular trafficking in eukaryotic cells. During the large-scale sequencing analysis of a human fetal brain cDNA library, we isolated a cDNA clone encoding a novel Rab protein, which showed 74.2% identity with previously isolated Rab39A at the amino acid level. RAB39B was expressed in a variety of human tissues and located in human chromosome Xq28. It consisted of two exons spanning 3764 bp of human genomic DNA. 相似文献
966.
Gao C Mao S Ditzel HJ Farnaes L Wirsching P Lerner RA Janda KD 《Bioorganic & medicinal chemistry》2002,10(12):4057-4065
A novel random peptide library was constructed using a phage-display format on the coat proteins pVII and pIX of filamentous bacteriophage. Panning against B-lymphocyte WI–L2 cells yielded one unique peptide-phage, denoted CHL8, that specifically bound to and penetrated the cells. Studies of each peptide derived from CHL8, denoted pep7 and pep9, established that only pep7 mediated the observed activity and only as a homodimer. Peptide libraries displayed on pVII–pIX should serve as a novel source of bioactive ligands for a variety of applications. 相似文献
967.
癫痫发作敏感大鼠前深梨状皮层T区GABA免疫反应活性变化 总被引:1,自引:0,他引:1
γ-氨基丁酸(γ-aminobutyric acid,GABA)是脑内最重要的抑制性神经递质,在阻断兴奋扩布及传导中起重要作用,其参与抗癫痫作用已被证实.有研究表明:前深梨状皮层T区是颞叶癫痫的始动部位.我们从前的工作已证明:惊厥剂量的红藻氨酸(Kainic acid,A)诱发SD大鼠出现急性癫痫发作后的5~7 d,动物出现癫痫发作敏感性长期增强,而蝎毒(scorpion venom,V)可通过增强海马结构内GABA的表达,对抗其癫痫发作敏感性的形成.本研究采用免疫组化技术,并探讨其与癫痫发作敏感长期增强的可能关系,检测癫痫发作敏感大鼠和经SV处理后癫痫发作敏感性明显降低的大鼠前深梨状皮层T区的GABA免疫反应活性变化. 相似文献
968.
Development of targeted biological agents against agricultural insect pests is of prime importance for the elaboration and implementation of integrated pest management strategies that are environment-friendly, respectful of bio-diversity and safer to human health through reduced use of chemical pesticides. A major goal to understand how Bt toxins work is to elucidate the functions of their three domains. Domains II and III are involved in binding specificity and structural integrity, but the function of Domain I remains poorly understood. Using a Manduca sexta BBMV (brush border membrane vesicles) system, we analyzed its responses to Cry1Aa 15 single-point mutations with altered Domain I helix 4 residues. Light scattering assay showed that toxicity was almost lost in 3 mutants, and we observed significantly reduced toxicity in other 7 mutants. However, 5 mutants retained wild-type toxicity. Using computer software, we simulated the three-dimensional structures of helix 4. Both experimental and bioinformatic analysis showed that residues in Cry1Aa Domain I helix 4 were involved in the formation of ion channels that is critical for its insect toxicity. 相似文献
969.
970.
A method for probing the interaction process between ionic surfactant and protein was developed with series piezoelectric quartz crystal (SPQC) sensing technique. It was based on the sensitive response of the SPQC sensor to the change in solution conductivity. A new relationship between the sensor response and the properties of ionic species in solution was derived. The method was used to examine the interaction process of two surfactants, cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), with lysozyme in aqueous solution. The obtained experimental results were in agreement with those of other methods from references. These results had been discussed. It was shown that the new method developed here was a useful and promising tool for probing the ionic surfactant-protein interaction process and might find more applications in similar studies. 相似文献