Molecular Dynamics Simulation of Temperature-dependent Flexibility of Thermophilic Xylose Isomerase

有 D 木糖的 Thermus thermophilus 木糖 isomerase (TtXI ) 的复杂模型被构造，并且分子的动力学(MD ) 模拟被 NAMD2.5 为 10 ns 在 300 和 360 K 执行。旋转(Rg ) 的半径，子单元相互作用，和残余灵活性被分析。结果表演残余 6069， 142148， 169172，和 332340 在 300 和 360 K 有高灵活性。有在 360 K 的更高的灵活性的残余能主要在 300 K 比那被划分成二个组：一个人在由残余组成的 helix-loop-helix 区域定位 5580 在里面催化领域；其它在子单元连接。在 360 K 的催化领域的 Rg 显示出 0.16 吗？高，比那，在小 C 终端的 300 K，而是 Rg，领域没有明显的差别。结果显示催化领域的那提高的 Rg 可以导致 TtXI 的活跃地点的强烈运动并且支持 D 木糖 isomization 反应。八张氢契约和五离子对与 300 K 相比在 360 K 在子单元接口被减少，那可以是为在在在 TtXI 的高温度的活动的刚硬和增加的减少的主要原因。也，解释 TtXI E372G 异种的冷改编的现象的帮助以前报导了的这结果。我们的结果揭示在温度和 TtXI 的结构灵活性之间的关系，并且在与多重子单元理解 thermophile 蛋白质的 thermostability 起一个重要作用。

Clavirolide G,a new rare dolabellane-type diterpenoid from the Xisha soft coral Clavularia viridis

One new dolabellane-type diterpenoid.named clavirolide C（1）,and one known related analogue（3）.have been isolated from the soft coral Cavularia viridis collected off the Xisha Islands in the South China Sea.Its structure and absolute configuration were determined on the basis of spectroscopic analysis,electronic circular dichroism.and compared with literature model compounds.The cytotoxic activity of these two compounds was evaluated against a panel of human tumor cell lines.Compound 1 showed moderate cytotoxic activity against KB and HL-60 cells.

Synthesis and biological evaluation of 5'-phenyl-3'H-spiro-[indoline-3,2'-[1,3,4]oxadiazol]-2-one analogs

A series of 5＇-phenyl-3＇H-spiro[indoline-3,2＇-[l,3,4]thiadiazol]-2-one analogs were synthesized and their Bcl-2 protein inhibitory activities were studied. The lead compound was originally identified using a fluorescence polarization-based competitive binding assay. Among the 10 compounds investigated, I k showed good binding affinities to Bcl-xL and Mcl-l, with inhibition constants of 8.9 μmol/L and 3.4 μmol/L, respectively. While compound lc achieved tight binding affinities to Bcl-xL （Ki= 0.16 μmol/L）, has the potential to be a new lead compound.

Insight into the role of cholesterol in modulation of morphology and mechanical properties of CH0-K1 cells: An in situ AFM study

Cholesterol plays a significant role in the organization of lipids and modulation of membrane dynamics in mammalian cells. However, the effect of cholesterol depletion on the eukaryotic cell membranes seems controversial. In this study, the effects of cholesterol on the topography and mechanical behaviors of CHO-K1 cells with manipulated membrane cholesterol contents were investigated by atomic force microscopy (AFM) technique. Here, we found that the depletion of cholesterol in cell membranes could increase the membrane stiffness, reduce the cell height as well as promote cell retraction and detachment from the surface, whereas the cholesterol restoration could reverse the effect of cholesterol depletion on the membrane stiffness. Increased methyl-β-cyclodextrin levels and incubation time could significantly increase Young’s modulus and degree of stiffing on cell membrane and cytoskeleton. This research demonstratede importance of cholesterol in regulating the dynamics of cytoskeleton-mediated processes. AFM technique offers excellent advantages in the dynamic monitoring of the change in membranes mechanical properties and behaviors during the imaging process. This promising technology can be utilized in studying the membrane properties and elucidating the underlying mechanism of distinct cells in the near-native environment.

An efficient etherification of Ginkgol biloba extracts with fewer side effects in a micro-flow system

In this study, etherification of ginkgolide B and dimethylaminoethyl chloride hydrochloride was investigated as a model reaction in a micro-flow system （MFS）, providing the resulting ethers in high yield with fewer side effects. Meanwhile, this novel process in MFS worked well for other ginkgolides from Ginkgol biloba and halides, giving moderate yields.