Artificial Splitting of a Non‐Ribosomal Peptide Synthetase by Inserting Natural Docking Domains

The interaction in multisubunit non‐ribosomal peptide synthetases (NRPSs) is mediated by docking domains that ensure the correct subunit‐to‐subunit interaction. We introduced natural docking domains into the three‐module xefoampeptide synthetase (XfpS) to create two to three artificial NRPS XfpS subunits. The enzymatic performance of the split biosynthesis was measured by absolute quantification of the products by HPLC‐ESI‐MS. The connecting role of the docking domains was probed by deleting integral parts of them. The peptide production data was compared to soluble protein amounts of the NRPS using SDS‐PAGE. Reduced peptide synthesis was not a result of reduced soluble NRPS concentration but a consequence of the deletion of vital docking domain parts. Splitting the xefoampeptide biosynthesis polypeptide by introducing docking domains was feasible and resulted in higher amounts of product in one of the two tested split‐module cases compared to the full‐length wild‐type enzyme.     

Constrained Dipeptide Surrogates: 5- and 7-Hydroxy Indolizidin-2-one Amino Acid Synthesis from Iodolactonization of Dehydro-2,8-diamino Azelates

The constrained dipeptide surrogates 5- and 7-hydroxy indolizidin-2-one N-(Boc)amino acids have been synthesized from L-serine as a chiral educt. A linear precursor ∆⁴-unsaturated (2S,8S)-2,8-bis[N-(Boc)amino]azelic acid was prepared in five steps from L-serine. Although epoxidation and dihydroxylation pathways gave mixtures of hydroxy indolizidin-2-one diastereomers, iodolactonization of the ∆⁴-azelate stereoselectively delivered a lactone iodide from which separable (5S)- and (7S)-hydroxy indolizidin-2-one N-(Boc)amino esters were synthesized by sequences featuring intramolecular iodide displacement and lactam formation. X-ray analysis of the (7S)-hydroxy indolizidin-2-one N-(Boc)amino ester indicated that the backbone dihedral angles embedded in the bicyclic ring system resembled those of the central residues of an ideal type II’ β-turn indicating the potential for peptide mimicry.     

用偏光织构及透射光谱分析液晶器件的老化

对一组台式计算器液晶显示器进行了光辐照,研究了光辐照对液晶显示器件显示品质的影响。采用偏光显微镜观察到了辐照后液晶的偏光织构的变化,液晶中出现了平行的条纹状织构和失去消光作用的黑洞,随着接受光辐照时间的增加,黑洞数量越来越多,面积越来越大。通过由计算机控制的双光束紫外-可见分光光度计测试了透射光谱的变化,发现其透射率随着接受光辐照时间的增加而降低。分析结果表明,条纹状织构和黑洞的出现是由于液晶分子结构在紫外线的照射下发生了变化所致,失去消光作用的黑洞是导致液晶器件透射率持续下降的主要原因。     

一种新型偶氮染料在扭曲向列相液晶显示取向中的应用

研究了一种新型偶氮材料sy03在光控取向中的应用。将sy03加入聚酰亚胺SE-3310(Nissan)与N,N-二甲基甲酰胺(DMF)的混合溶液中作为90°扭曲向列相液晶显示(Twisted nematic liquid crystal display,TN-LCD)的光取向材料,测量由它作为取向膜的扭曲向列型盒的电光特性与仅用SE-3310取向的扭曲向列型盒电光特性比较,发现sy03偶氮的加入使得扭曲向列型盒的响应时间短到98 ms、阈值电压也降低到1.7 V左右。而且随曝光时间的增加,响应时间和衬比度都有所提高,电光响应曲线也更为陡峭。加热到150℃后,其电光特性并没有明显变化,证明了它良好的热稳定性。最后通过测量偏振紫外吸收光谱,分析得出液晶分子易取向方向与激发光源偏振方向垂直。     

光锥与TDI-CCD耦合监控中测试目标的一种实现方法

为了给光锥与时间延迟积分电荷耦合器件耦合监控装置提供有效的被测运动条纹,分析了传统推扫成像实验装置的不足之处,设计了电子显示目标滚屏运动装置.采用光学相机对印刷条纹静止成像,并用TDI-CCD数字相机对监视器屏幕上的运动条纹动态成像.实验结果表明,该方案解决了高分辨率的鉴别率图样无法在监视器或投影仪上精确显示的困难.与传统的实验室模拟装置相比,该方案提高了鉴别率条纹的运动稳定性,减小了条纹运动速率与TDI-CCD扫描行频间的失配误差,不仅能够对耦合过程实施监控,而且还能用于耦合系统的像质评价.     

Structural Insights into the Design of Synthetic Nanobody Libraries

Single domain antibodies from camelids, or nanobodies, are a unique class of antibody fragments with several advantageous characteristics: small monomeric size, high stability and solubility and easy tailoring for multiple applications. Nanobodies are gaining increasing acceptance as diagnostic tools and promising therapeutic agents in cancer and other diseases. While most nanobodies are obtained from immunized animals of the camelid family, a few synthetic nanobody libraries constructed in recent years have shown the capability of generating high quality nanobodies in terms of affinity and stability. Since this synthetic approach has important advantages over the use of animals, the recent advances are indeed encouraging. Here we review over a dozen synthetic nanobody libraries reported so far and discuss the different approaches followed in their construction and validation, with an emphasis on framework and hypervariable loop design as critical issues defining their potential as high-class nanobody sources.     

促红细胞生成素B螺旋表面肽的代谢稳定性结构修饰：设计、合成及其提高的肾保护作用

肾脏缺血缺氧以及再灌注过程都将导致肾小管上皮细胞凋亡,使肾功能严重受损.肾脏的缺血再灌注损伤是移植肾功能延迟恢复的主要原因并能诱导急慢性排斥,影响肾存活率.近年来发现,衍生于促红细胞生成素（EPO）的B螺旋亚基亲水表面序列的肽链（HBSP）,对肾脏缺血再灌注损伤具有显著的保护作用,但其在体内极短的半衰期（约2min）极大地限制了它的临床应用.因此,本研究采用构象约束、全D-构型氨基酸替换和N-端封闭策略,设计了3种类型的EPOB螺旋表面肽衍生物,旨在提高其代谢稳定性环肽的设计采用了对氧化还原稳定的硫醚键和相对刚性的亚砜键两种环合方式.在多肽的合成上,采用微波辅助多肽自动合成和手工合成两种模式有机结合;优化了硫醚环合工艺,应用微波加热进行硫醚环肽的合成,大大提高了产率和效率;利用圆二色（CD）谱确定了亚砜环肽的相对构型.活性实验表明,相对于线性母肽HBSP,本文设计合成的代谢稳定衍生肽对大/小鼠肾脏缺血再灌注损伤均有显著提高的保护作用,且硫醚和R-构型亚砜环肽的肾脏保护活性强于S-构型亚砜环肽.而且,环化确实提高了功能肽的血浆稳定性.因此,本文合成的硫醚环肽一周一次注射剂量等效于线性肽HBSP一日三次剂量对小鼠肾损伤的保护作用.     

Treatment of Human Glioblastoma U251 Cells with Sulforaphane and a Peptide Nucleic Acid (PNA) Targeting miR-15b-5p: Synergistic Effects on Induction of Apoptosis

Glioblastoma multiforme (GBM) is a lethal malignant tumor accounting for 42% of the tumors of the central nervous system, the median survival being 15 months. At present, no curative treatment is available for GBM and new drugs and therapeutic protocols are urgently needed. In this context, combined therapy appears to be a very interesting approach. The isothiocyanate sulforaphane (SFN) has been previously shown to induce apoptosis and inhibit the growth and invasion of GBM cells. On the other hand, the microRNA miR-15b is involved in invasiveness and proliferation in GBM and its inhibition is associated with the induction of apoptosis. On the basis of these observations, the objective of the present study was to determine whether a combined treatment using SFN and a peptide nucleic acid interfering with miR-15b-5p (PNA-a15b) might be proposed for increasing the pro-apoptotic effects of the single agents. To verify this hypothesis, we have treated GMB U251 cells with SFN alone, PNA-a15b alone or their combination. The cell viability, apoptosis and combination index were, respectively, analyzed by calcein staining, annexin-V and caspase-3/7 assays, and RT-qPCR for genes involved in apoptosis. The efficacy of the PNA-a15b determined the miR-15b-5p content analyzed by RT-qPCR. The results obtained indicate that SFN and PNA-a15b synergistically act in inducing the apoptosis of U251 cells. Therefore, the PNA-a15b might be proposed in a “combo-therapy” associated with SFN. Overall, this study suggests the feasibility of using combined treatments based on PNAs targeting miRNA involved in GBM and nutraceuticals able to stimulate apoptosis.     

用于显示的透射型法布里-珀罗光调制器

提出了一种用于显示的,基于透射型法布里-珀罗干涉的微机电系统(MEMS)光学调制器。基于多光束干涉原理分析了调制器的光学特性,推导出了调制器结构的特征参量。分析表明,当调制器的腔长为cλ/4时,透射光可以实现暗态显示;当调制器的腔长取为零或cλ/2时,透射光可以实现亮态显示。通过控制法布里-珀罗腔长,就可实现调制器的明暗调制。理论上证明了该调制器用于显示的可行性。设计了一种基于微机电系统的透射型法布里-珀罗光学调制器结构,该调制器的理论衬比度达到150。仿真结果表明,该调制器具有2.4 V的低电压静电驱动性能。