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排序方式: 共有593条查询结果,搜索用时 25 毫秒
51.
VG Kolupaeva TV Pestova CU Hellen IN Shatsky 《Canadian Metallurgical Quarterly》1998,273(29):18599-18604
A complex of eukaryotic initiation factors (eIFs) 4A, 4E, and 4G (collectively termed eIF4F) plays a key role in recruiting mRNAs to ribosomes during translation initiation. The site of ribosomal entry onto most mRNAs is determined by interaction of the 5'-terminal cap with eIF4E; eIFs 4A and 4G may facilitate ribosomal entry by modifying mRNA structure near the cap and by interacting with ribosome-associated factors. eIF4G recruits uncapped encephalomyocarditis virus (EMCV) mRNA to ribosomes without the involvement of eIF4E by binding directly to the approximately 450-nucleotide long EMCV internal ribosome entry site (IRES). We have used chemical and enzymatic probing to map the eIF4G binding site to a structural element within the J-K domain of the EMCV IRES that consists of an oligo(A) loop at the junction of three helices. The oligo(A) loop itself is not sufficient to form stable complexes with eIF4G since alteration of its structural context abolished its interaction with eIF4G. Addition of wild type or trans-dominant mutant forms of eIF4A to binary IRES.eIF4G complexes did not further alter the pattern of chemical/enzymatic modification of the IRES. 相似文献
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53.
Marinne Nikolov 《Pedagogy, Culture & Society》2003,11(3):443-447
Educational Controversies: towards a discourse of reconciliation PAMELA LEPAGE & HUGH SOCKETT, 2002 London: RoutledgeFalmer 155 pp., £51.46, ISBN 0 415 27066 9 (hardback) 相似文献
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55.
Solubility of fatty acids in supercritical carbon dioxide 总被引:1,自引:0,他引:1
P. Maheshwari Z. L. Nikolov T. M. White R. Hartel 《Journal of the American Oil Chemists' Society》1992,69(11):1069-1076
The solubilities of lauric, linoleic, myristic, oleic, palmitic and stearic acid in supercritical carbon dioxide (SC-CO2) at different pressures and temperatures were measured. The solubility values obtained in this work were compared with previously
published data, and possible causes for observed discrepancies were discussed. The solubilities of the six fatty acids were
modeled by Chrastil’s equation, and estimated model parameters were used to plot the solubility isotherms of fatty acids at
313, 323 and 333°K (40, 50 and 60°C) as a function of SC-CO2 density. The comparison of solubility isotherms of fatty acids and vegetable oil suggests that separation of fatty acids
from triglycerides might be possible by using SC-CO2 at densities less than 700 kg/m3. From the effect of temperature on fatty-acid and vegetable-oil solubility, it seems that the extraction yield could be increased
without sacrificing the selectivity of SC-CO2 for fatty acids by choosing a higher operating temperature. The data also suggest that fractionation of certain fatty acids
might be possible by manipulating the processing conditions. Given the values of the constants, Chrastil’s equation could
serve as a guideline for choosing appropriate processing conditions and predicting the effect of pressure and temperature
of SC-CO2 on solute solubility. 相似文献
56.
锦屏一、二级电站对外交通专用公路羊房沟段部分边坡开挖后高度为35 m,地质条件极差,多为严重风化的岩石并夹杂大量泥沙,裂隙发育。为此,设计在此类路段使用1 000 kN级预应力锚索,配合3 m长锚杆对开挖边坡进行加固。锚索的注浆体为水泥净浆,锚索体为符合“预应力混凝土用钢绞线”GB/T 5224-2003和A STM A 416-94标准生产的1 860 M Pa高强度低松弛钢绞线。介绍了该段中K 46 319.84~K 46 520.16段工程施工中的锚索施工技术。 相似文献
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58.
Chen Luojing; Coutinho Pedro M.; Nikolov Zivko; Ford Clark 《Protein engineering, design & selection : PEDS》1995,8(10):1049-1055
The large form of glucoamylase (GAI) from Aspergillus awamori(EC 3.2.1.3
[EC]
) binds strongly to native granular starch, whereasa truncated form (GAII) which lacks 103 C-terminal residues,does not. This C-terminal region, conserved among fungal glucoamylasesand other starch-degrading enzymes, is part of an independentstarch-binding domain (SBD). To investigate the SBD boundariesand the function of conserved residues in two putative substrate-bindingsites, five gluco-amylase mutants were constructed with extensivedeletions in this region for expression in Saccharomyces cerevisiae.Progressive loss of both starch-binding and starch-hydrolyticactivity occurred upon removal of eight and 25 C-terminal aminoacid residues, or 21 and 52 residues close to the N-terminus,confirming the requirement for the entire region in formationof a functional SBD. C-terminal deletions strongly impairedSBD function, suggesting a more important role for one of theputative binding sites. A GAII phenocopy showed a nearly completeloss of starch-binding and starch-hydrolytic activity. The deletionsdid not affect enzyme activity on soluble starch or thermo-stabilityof the enzyme, confirming the independence of the catalyticdomain from the SBD. 相似文献
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