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Conserved folding in retroviral proteases: crystal structure of a synthetic HIV-1 protease 总被引：57，自引：0，他引：57
A Wlodawer M Miller M Jaskólski B K Sathyanarayana E Baldwin I T Weber L M Selk L Clawson J Schneider S B Kent 《Science (New York, N.Y.)》1989,245(4918):616-621
The rational design of drugs that can inhibit the action of viral proteases depends on obtaining accurate structures of these enzymes. The crystal structure of chemically synthesized HIV-1 protease has been determined at 2.8 angstrom resolution (R factor of 0.184) with the use of a model based on the Rous sarcoma virus protease structure. In this enzymatically active protein, the cysteines were replaced by alpha-amino-n-butyric acid, a nongenetically coded amino acid. This structure, in which all 99 amino acids were located, differs in several important details from that reported previously by others. The interface between the identical subunits forming the active protease dimer is composed of four well-ordered beta strands from both the amino and carboxyl termini and residues 86 to 94 have a helical conformation. The observed arrangement of the dimer interface suggests possible designs for dimerization inhibitors. 相似文献
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Rational design of enzymes is a stringent test of our understanding of protein chemistry and has numerous potential applications. Here, we present and experimentally validate the computational design of enzyme activity in proteins of known structure. We have predicted mutations that introduce triose phosphate isomerase activity into ribose-binding protein, a receptor that normally lacks enzyme activity. The resulting designs contain 18 to 22 mutations, exhibit 10(5)- to 10(6)-fold rate enhancements over the uncatalyzed reaction, and are biologically active, in that they support the growth of Escherichia coli under gluconeogenic conditions. The inherent generality of the design method suggests that many enzymes can be designed by this approach. 相似文献
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赵飞 《安徽农业大学学报》2011,(3):134-137
工业设计具有很强的综合性和系统性，时尚因素在工业设计中起着重要的作用，它对于工业设计有着各式各样的影响，文章从时尚所引领的生活方式、时尚对于工业设计产品的视觉形态、设计主题和经济性四个方面分析时尚因素对于工业设计的影响，重新认识时尚与工业设计的关系，对工业设计中如何利用时尚做出更好的设计提出有益的启示。 相似文献
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分析了城市道路景观的构成要素,以及城市道路景观设计的地域文化性的含义。从城市所面临的缺乏本土地域文化特征的危机出发,通过对白水县杜康东路景观设计实例的分析研究,解析了白水县的城市文化背景、项目概况和设计定位、设计指导思想以及总体构思与节点布局,以探讨如何在城市道路景观设计中合理运用本土地域文化,并且以地域文化为重要的创作源泉,吸收其有益的"基因",营造具有地域文化特色的城市道路景观,从而更好地展现城市的鲜明个性与特色。 相似文献
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[目的]研究广昌白莲蛋白的提取工艺,找出最佳的提取条件。[方法]分别采用直接提取、酸化提取和碱化提取3种不同的方法对广昌白莲蛋白进行提取,并利用正交试验设计来确定其最佳的料液比、pH值和浸提时间。[结果]广昌白莲的最佳提取工艺条件∶料液比1∶15、pH值7、浸提时间20h,此时的蛋白提取率为5.79%。[结论]该研究为广昌白莲活性成份的提取提供了参考依据。 相似文献
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苍耳SRAP-PCR体系优化设计方案比较 总被引：3，自引：1，他引：2
采用正交设计和均匀设计对苍耳SRAP-PCR反应体系进行优化,并对2种设计方案优化出的最佳反应体系的可靠性和稳定性进行比较,结果表明:2种设计均可用于苍耳SRAP-PCR体系的优化,但与正交设计相比较,均匀设计可以使试验次数大大减少,避免盲目性,在多因素多水平条件下,快速得到条带清晰、稳定性好的最优SRAP-PCR体系.通过试验比较筛选出苍耳的SRAP-PCR最佳反应体系为:2.5μL 10×PCRbuffer,30 ng模板DNA,Mg2+2.5 mmol/L,dNTP 1.5 mmol/L,引物0.3μmol/L,Taq DNA聚合酶1U,总体积25μL. 相似文献
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菲律宾蛤仔是我国四大养殖贝类之一,营养丰富,蛋白含量高,具有食用和药用价值.从菲律宾蛤仔中提取的氨基多糖、糖胺聚糖、糖蛋白、活性多肽等物质,具有抗肿瘤、抗氧化、降血脂、增强免疫力及抗动脉粥样硬化等作用,本文综述这些生物活性成分的研究现状,为海洋功能食品和海洋药物的研发提供参考. 相似文献
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Heterogeneity in the experimental material is an important problem to deal with the designing of scientific experiments. Block designs are useful in controlling heterogeneity arising due to one source. A Randomized Complete Block (RCB) design is the simplest and commonly used block design. When the number of treatments in an experiment increases, incomplete block designs with smaller block sizes can be adopted. Balanced Incomplete Block (BIB) and Partially Balanced Incomplete Block (PBIB) designs are two important types of such designs. PBIB designs are extremely wide spread in literature. For ready referencing and potential use of these designs, online software for generation and analysis of these designs is highly desirable. This paper describes the development of a complete web solution for generation and analysis of PBIB designs using client–server architecture. An e-learning material on these designs is also prepared that can be used as reference material by researchers and students working in this area. WS-PBIBD is accessible any time from arbitrary platforms through internet. This software would help researchers in planning, designing and analyzing their experiments through web. 相似文献
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论述了现代花艺的特点、表现,和东西方现代花艺的发展。结合创作实践论述了现代花艺造型创新设计应重点突出的要素、手法,创新理念培养应关注的方面及其对现代花艺设计的具体影响;提出了目前国内现代花艺发展中应克服的问题。 相似文献
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Acetylcholine receptor: an allosteric protein 总被引：51，自引：0，他引：51
The nicotine receptor for the neurotransmitter acetylcholine is an allosteric protein composed of four different subunits assembled in a transmembrane pentamer alpha 2 beta gamma delta. The protein carries two acetylcholine sites at the level of the alpha subunits and contains the ion channel. The complete sequence of the four subunits is known. The membrane-bound protein undergoes conformational transitions that regulate the opening of the ion channel and are affected by various categories of pharmacologically active ligands. 相似文献
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分析了居住区绿地景观设计的原则,强调居住区景观设计应遵循体现地方特色,因地制宜;明确居住区功能要求;景观设计与建筑设计有机结合;强化中心、创造层次感和围合感;人性化;生态化的设计原则。在此基础上,从意境创造和植物配置方面探讨了居住区绿地景观设计的措施,在植物配置方面强调空间处理、线形变化、季相变化,以及种植具有环境保护作用和经济效益的植物。希望这些思考能够对未来居住区景观规划和建设起到积极作用。 相似文献
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Part II analyses approach C experiments. Field-scale experiments were applied to four wheat fields in the Western Australian wheat belt. Different experimental designs were used two two-dimensional sine-waves, a chequerboard, and a two-factor strip arrangement. In each experiment, the yield associated with a particular treatment was predicted by kriging to where the other treatments were located. Different forms of kriging were investigated. Co-located cokriging, using the previous-season yield map as a covariate, was the most promising. The kriged data were then modelled with polynomial yield response functions. The outcome was a map for each field that described the optimum application of experimental input. The requirements varied continuously across the field, and could justify future site-specific crop management. The two-factor strip experiment was the most successful of those presented; the field on which it was used showed relatively strong responses to the applied inputs. The other sites were affected by lack of rain and/or design flaws. The underlying philosophy is sound, but the method proposed is time-consuming and inefficient. We hope that this paper can stimulate further research on the subject. 相似文献
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浑水水力分离清水装置的优化试验研究 总被引：1，自引：1，他引：1
运用均匀正交设计法和投影寻踪回归分析法（PPR）对浑水水力分离清水装置进行优化试验研究。通过选用高度、底孔、浓度、进流量4个主要影响因素对浑水分离清水装置进行了均匀正交试验，并且利用投影寻踪回归分析方法对试验结果进行了数据分析及计算机仿真优化，明确了耗水率的主要影响因素是底孔和高度，溢流含沙量的主要影响因素是浓度，表面负荷率的主要影响因素是进流量。 相似文献
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The active sites of 491 human protein kinase domains are highly conserved, which makes the design of selective inhibitors a formidable challenge. We used a structural bioinformatics approach to identify two selectivity filters, a threonine and a cysteine, at defined positions in the active site of p90 ribosomal protein S6 kinase (RSK). A fluoromethylketone inhibitor, designed to exploit both selectivity filters, potently and selectively inactivated RSK1 and RSK2 in mammalian cells. Kinases with only one selectivity filter were resistant to the inhibitor, yet they became sensitized after genetic introduction of the second selectivity filter. Thus, two amino acids that distinguish RSK from other protein kinases are sufficient to confer inhibitor sensitivity. 相似文献
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采用四因子二次通用旋转设计,以抑菌率为测定指标,对胃蛋白酶水解革胡子鲶Claris lareza鱼骨蛋白的条件进行了优化,同时测定了酶解产物中可溶性肽的含量,以分析抑菌率与可溶性肽含量之间的相关关系。经Design Expert7．1．2软件优化,得出胃蛋白酶酶解鲶鱼骨蛋白的最优条件为：底物浓度0．277kg／L,加酶量1408U／g,水解温度39．2℃,水解时间4．86h,在此条件下获得的水解物,对大肠杆菌、藤黄微球菌及枯草芽孢杆菌的抑菌率分别为71．40％、56．88％和64．54％。通过SAS软件分析二者的相关性,发现可溶性肽含量和抑菌率之间并不存在相关性。 相似文献
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以酸浆植物的叶子为试材制作叶茶,研究杀青次数(3、4、5、6、7、8、9次)及萎凋4h后杀青次数(3、4、5、6、7、8、9次)对其活性成分的影响。结果表明:酸浆叶茶中类黄酮的含量随着杀青次数的增加而增大,茶多糖、粗蛋白的含量随着杀青次数的增加而减小,茶多酚的含量在炒5次时最大;而萎凋4h后酸浆叶茶中类黄酮、茶多酚的含量比不萎凋的酸浆叶茶中含量低,萎凋4h后酸浆叶茶中茶多糖、粗蛋白含量比不萎凋的酸浆叶茶中含量高。 相似文献