Hybrid Photopatterned Enzymatic Reaction (HyPER) for in Situ Cell Manipulation

The ability to design artificial extracellular matrices as cell‐instructive scaffolds has opened the door to technologies capable of studying the fate of cells in vitro and to guiding tissue repair in vivo. One main component of the design of artificial extracellular matrices is the incorporation of biochemical cues to guide cell phenotype and multicellular organization. The extracellular matrix (ECM) is composed of a heterogeneous mixture of proteins that present a variety of spatially discrete signals to residing cell populations. In contrast, most engineered ECMs do not mimic this heterogeneity. In recent years, photo‐deprotection has been used to spatially immobilize signals. However, this approach has been limited mostly to small peptides. Here we combine photo‐deprotection with enzymatic reaction to achieve spatially controlled immobilization of active bioactive signals that range from small molecules to large proteins. A peptide substrate for transglutaminase factor XIII (FXIIIa) was caged with a photo‐deprotectable group, which was then immobilized to the bulk of a cell‐compatible hydrogel. With focused light, the substrate can be deprotected and used to immobilize patterned bioactive signals. This approach offers an innovative strategy to immobilize delicate bioactive signals, such as growth factors, without loss of activity and enables in situ cell manipulation of encapsulated cells.     

Using 15N‐Ammonium to Characterise and Map Potassium Binding Sites in Proteins by NMR Spectroscopy

A variety of enzymes are activated by the binding of potassium ions. The potassium binding sites of these enzymes are very specific, but ammonium ions can often replace potassium ions in vitro because of their similar ionic radii. In these cases, ammonium can be used as a proxy for potassium to characterise potassium binding sites in enzymes: the ¹H,¹⁵N spin‐pair of enzyme‐bound ¹⁵NH₄⁺ can be probed by ¹⁵N‐edited heteronuclear NMR experiments. Here, we demonstrate the use of NMR spectroscopy to characterise binding of ammonium ions to two different enzymes: human histone deacetylase 8 (HDAC8), which is activated allosterically by potassium, and the bacterial Hsp70 homologue DnaK, for which potassium is an integral part of the active site. Ammonium activates both enzymes in a similar way to potassium, thus supporting this non‐invasive approach. Furthermore, we present an approach to map the observed binding site onto the structure of HDAC8. Our method for mapping the binding site is general and does not require chemical shift assignment of the enzyme resonances.     

Pneumocandin Biosynthesis: Involvement of a trans‐Selective Proline Hydroxylase

Echinocandins are cyclic nonribosomal hexapeptides based mostly on nonproteinogenic amino acids and displaying strong antifungal activity. Despite previous studies on their biosynthesis by fungi, the origin of three amino acids, trans‐4‐ and trans‐3‐hydroxyproline, as well as trans‐3‐hydroxy‐4‐methylproline, is still unknown. Here we describe the identification, overexpression, and characterization of GloF, the first eukaryotic α‐ketoglutarate/Fe^II‐dependent proline hydroxylase from the pneumocandin biosynthesis cluster of the fungus Glarea lozoyensis ATCC 74030. In in vitro transformations with L ‐proline, GloF generates trans‐4‐ and trans‐3‐hydroxyproline simultaneously in a ratio of 8:1; the latter reaction was previously unknown for proline hydroxylase catalysis. trans‐4‐Methyl‐L ‐proline is converted into the corresponding trans‐3‐hydroxyproline. All three hydroxyprolines required for the biosynthesis of the echinocandins pneumocandins A₀ and B₀ in G. lozoyensis are thus provided by GloF. Sequence analyses revealed that GloF is not related to bacterial proline hydroxylases, and none of the putative proteins with high sequence similarity in the databases has been characterized so far.     

生物质水解制备糠醛的研究进展

生物质中的碳水化合物是当今世界最重要的可再生资源,将这部分资源转化为附加值较高的化工产品以代替日趋枯竭的化石资源,势必成为绿色化学发展的重点。典型生物质中半纤维素的含量高达30%,经催化水解为五碳糖后再进一步脱水可得到重要的平台化合物糠醛。综述了生物质催化水解制备糠醛的研究进展并对未来的研究趋势进行了展望。     

地下水除铁锰装置的工艺设计及其应用

本文介绍了地下水除铁锰装置的工艺设计、原理及流程安装、操作程序，并根据应用实例，证明了含铁锰过量的地下水，采用充氧曝气接触催化氧化法处理后，其水质符合国家ＧＢ５７４９－８５规定的饮用水标准。     

甲醇制丙烯反应中ZSM-5分子筛催化剂积炭失活介尺度机制研究

甲醇制丙烯（MTP）是当前煤化工领域亟需发展的关键催化技术,积炭被认为是导致催化剂失活的重要原因之一。以积炭分子筛为研究对象,通过IGA、FTIR及TG等多种表征手段,考察甲醇的吸附行为、分子筛表面酸性、积炭成分与MTP反应中甲醇反应活性之间的构效关系。研究结果表明,甲醇的吸附量随催化剂的失活而降低,其下降速率与甲醇转化率成正比。催化剂上滞留的碳物种的主要成分为轻烃、BTX芳烃、活性结焦和积炭,而其中积炭是引起分子筛失活的主要原因。完全失活的催化剂与新鲜催化剂相比仍保留一定的甲醇吸附能力,推测积炭主要存在于酸活性中心周围。积炭首先覆盖的是B酸中心的羟基和桥式羟基,随后是非骨架Al—OH;而催化剂的甲醇转化率与分子筛中可接触的B酸和L酸数量成正比。另外,基于催化剂的失活速率与转化率存在的正比关系,结合反应动力学,推导出了失活曲线的数学表达式,理论上解释了MTP反应过程中的积炭失活介尺度机制。     

PdCo/SiO2双金属催化剂用于杂环储氢载体的高效脱氢

乙基咔唑/十二氢乙基咔唑（N-ethylcarbazole/dodecahydro-N-ethylcarbazole,NECZ/12H-NECZ）体系被认为在有机液体储氢领域具有较大的开发应用前景,但高活性、选择性的脱氢催化剂的设计开发制约着其工业应用。基于此,设计开发出一种具有高脱氢活性和高选择性的双金属催化剂Pd₁Co₃/ SiO₂（Pd质量分数为1.25%）,对其结构进行了XPS、XRD、HRTEM等表征分析,并评价了其催化十二氢乙基咔唑的脱氢性能。与5.0%（质量分数）Pd/SiO₂相比,表明引入一定量的Co金属形成的PdCo合金可提高12H-NECZ脱氢反应效率和NECZ选择性,动力学与DFT计算发现双金属催化剂可以有效降低三步基元反应的能垒,大幅提升第二步基元反应（8H-NECZ到4H-NECZ）的脱氢反应速率。研究结果为揭示12H-NECZ脱氢反应机理和高效脱氢反应催化剂的设计与开发提供了新的思路。     

g-C3N4/MIL-125(Ti)磁性复合材料制备及其去除罗丹明B

为解决能源短缺和环境污染等问题,探究半导体光催化材料去除有机污染物,以MIL-125(Ti)为光催化剂载体,g-C₃N₄为有机半导体,Fe₃O₄@SiO₂为磁性载体,通过溶剂热法合成了一系列不同质量配比的可见光响应型MIL-125(Ti)复合材料。通过傅里叶变换红外光谱仪、X射线衍射仪、场发射扫描电子显微镜、热重分析仪等对复合材料的样品组成、结构、形貌及光学性能等进行表征分析。进一步通过正交试验评价该复合材料去除罗丹明B的性能。研究结果表明,最适宜去除罗丹明B的操作工艺条件为：光催化时间为4.0h,g-C₃N₄与MIL-125(Ti)的质量配比为1∶20,催化剂投加量为0.01g,罗丹明B溶液的浓度为10.0mg/L。在该条件下罗丹明B的去除率可达到96.57%。经过4次循环实验后,去除率仍能达到86.52%。g-C₃N₄/MIL-125(Ti)磁性复合材料的制备工艺和去除有机染料机理可为相关研究提供借鉴。