Carbohydrate chain of ganglioside GM1 as a ligand: identification of the binding strategies of three 15 mer peptides and their divergence from the binding modes of growth-regulatory galectin-1 and cholera toxin

The branched pentasaccharide chain of ganglioside GM1 is a prominent cell surface ligand, for example, for cholera toxin or tumor growth-regulatory homodimeric galectins. This activity profile via protein recognition prompted us to examine the binding properties of peptides with this specificity. Our study provides insights into the mechanism of molecular interaction of this thus far unexplored size limit of the protein part. We used three pentadecapeptides in a combined approach of mass spectrometry, NMR spectroscopy and molecular modelling to analyze the ligand binding in solution. Availability of charged and hydrophobic functionalities affected the intramolecular flexibility of the peptides differently. Backfolding led to restrictions in two cases; the flexibility was not reduced significantly by association of the ligand in its energetically privileged conformations. Major contributions to the interaction energy arise from the sialic acid moiety contacting Arg/Lys residues and the N-terminal charge. Considerable involvement of stacking between the monovalent ligand and aromatic rings could not be detected. This carbohydrate binding strategy is similar to how an adenoviral fiber knob targets sialylated glycans. Rational manipulation for an affinity enhancement can now be directed to reduce the flexibility, exploit the potential for stacking and acquire the cross-linking capacity of the natural lectins by peptide attachment to a suitable scaffold.     

The influence of cosolvent polarity on the flow properties of hydroalcoholic gels: empirical models

The aim of this study was to investigate the influence of cosolvent polarity on the rheological flow properties of aqueous and hydroalcoholic gels obtained from the Carbopol Ultrez 10 base and used for topical applications. Specifically, we have examined the effect of pH (range 4.0--7.0) on the consistency and flow properties of dispersed systems in water and mixtures--15 : 85% v/v of methanol : water, ethanol : water, n-propanol : water and n-butanol : water--at a constant polymer concentration of 0.3% w/w. The gels, which had decreasing polarity values in the jellifying medium, showed qualitatively similar flow behavior, characteristic of pseudoplastic systems, and all of the flow curves were adjusted to the Ostwald model. Sigmoidal dose response functions were calculated to describe the flow and consistency indexes as a function of pH. As a result, the influence of alcohol polarity on the polymer network has been assessed meaningfully using the empirical parameters obtained: maximum consistency index value (k(max)), pH value required for 50% development of polymer network (pH(50)), and asymptotic flow index value (n(min)) for the fully structured gels.     

能直接读出摄氏温度数的石英晶体遥测温度计

尽管石英晶体已经用作温度传感器，但设计师却没有利用这一技术，其原因在于几乎没有一家制造商把石英晶体传感器作为标准产品来供应(参考文献1和2)。与采用电阻或半导体的传感器相比，采用石英晶体的传感器天生具有数字信号调节功能、良好的稳定性和无噪声的直接数字输出，因此最适合于遥感场合(图1）。     

“要命”的细节调查

着眼大局的同时,能否关注尽职调查的相关细节,决定收购兼并的成败。AMR的彼得·豪森（Peter Howson）告诉我们如何把握尽职调查尺度。     

CH_3F与C~(12)O_2和C~(13)O_2之间的振动能转移

我们采用Q开关的CO_2激光9.6μm P(20)支泵浦CH_3F分子的ν_3振动模,以此作为能源来激发C~(12)O_2和C~(13)O_2分子的弯曲振动模ν_2,研究其在非弹性碰撞过程中分子能量转移过程。我们用一种比红外荧光法(LIF)分辨率高一万倍的新方法——二极管激光探测法来得到     

镍镉电池预查验电路

镍镉电池由于电流容量大，因此广泛用于从计算机到电动工具的各种产品中。但镍镉电池出了名的缺点是，随着时间推移容量会减小。我在阅读《便携世界中的电池》这本书时，正在想着这些问题。第十章“充分利用电池—使用和恢复”让我眼前一亮，我意识到，终于有解决办法了。     

非平面多层外延双极功率集成电路工艺

用廉价的方式把数字、模拟和功率元件集成在单片衬底上的市场需求,在许多应用方面的重要性正在持续的增长。本文描述非平面多层外延双极型功率集成电路的工艺,此工艺特别适用于低成本电源的应用,例如串联—通道稳压器。本概念能提高晶体管特性,并能扩展到更为复杂更高性能的智能功率集成电路的应用领域。     

首席信息安全官的云策略指南

如今,“云计算”的概念如火如茶,“云计算”的电视广告也在电视台中频繁的出现,“云计算”给我们绘制出一幅美妙的未来蓝图,通过“云计算”企业可以大幅降低IT成本,提高工作效率,然而,对于企业来说,“云计算”的安全问题始终困扰着他们,如何安全的可靠的迁移到“云计算”,采用何种云策略对企业的首席信息安全官是一个巨大的考验。     

功率转换应用中更高集成度的挑战

终端产品的上市时间在不断缩短,意味着元件必须易于应用,而且满足终端产品更轻盈、小巧的要求,既在日益缩小的空间内集成更多的功能.这及其它种种元素推动了元件向更高集成度发展的趋势.在本文中,我们将从功率转换器方面看这一趋势的发展,说明单片集成水平的提高,以及要在相同的板级裸片上"塞入"更多信号和功率功能所带来的相应技术挑战.此外还适时地指出单片集成的挑战可以通过使用多芯片封装来化解.     

用先进工具和技术解决插板电磁辐射难题

钟频速度加快,插板密度更大,深亚微米芯片问世,再加上政府部门对EMC作出更严格的规限,迫使设计人员要“收紧”印制电路板的设计。但精良的EDA工具和先进的工程技术,可以有助于设计符合电磁规定的系统。