Chiral Nanozymes–Gold Nanoparticle‐Based Transphosphorylation Catalysts Capable of Enantiomeric Discrimination

Enantioselectivity in RNA cleavage by a synthetic metalloenzyme has been demonstrated for the first time. Thiols containing chiral Zn^II‐binding head groups have been self‐assembled on the surface of gold nanoparticles. This results in the spontaneous formation of chiral bimetallic catalytic sites that display different activities (k_cat) towards the enantiomers of an RNA model substrate. Substrate selectivity is observed when the nanozyme is applied to the cleavage of the dinucleotides UpU, GpG, ApA, and CpC, and remarkable differences in reactivity are observed for the cleavage of the enantiomerically pure dinucleotide UpU.     

Halogen Bonding Controls the Regioselectivity of the Deiodination of Thyroid Hormones and their Sulfate Analogues

The type 1 iodothyronine deiodinase (1D‐1) in liver and kidney converts the L ‐thyroxine ( T4 ), a prohormone, by outer‐ring (5′) deiodination to biologically active 3,3′,5‐triiodothyronine ( T3 ) or by inner‐ring (5) deiodination to inactive 3,3′,5′‐triiodothronine ( rT3 ). Sulfate conjugation is an important step in the irreversible inactivation of thyroid hormones. While sulfate conjugation of the phenolic hydroxyl group stimulates the 5‐deiodination of T4 and T3 , it blocks the 5′‐deiodination of T4 . We show that thyroxine sulfate ( T4S ) undergoes faster deiodination as compared to the parent thyroid hormone T4 by synthetic selenium compounds. It is also shown that ID‐3 mimics, which are remarkably selective to the inner‐ring deiodination of T4 and T3 , changes the selectivity completely when T4S is used as a substrate. From the theoretical investigations, it is observed that the strength of halogen bonding increases upon sulfate conjugation, which leads to a change in the regioselectivity of ID‐3 mimics towards the deiodination of T4S . It has been shown that these mimics perform both the 5′‐ and 5‐ring deiodinations by an identical mechanism.     

Protein‐like structure and activity in synthetic polymers

The structure and activity of proteins is the gold standard for functional polymeric materials. This highlight seeks to calibrate the reader with respect to recent attempts to mimic the various structural and functional traits of proteins using the techniques of modern polymer chemistry. From advances in sequence‐controlled polymers (primary structure), to peptidomimetics, foldamers, single‐chain nanoparticles (secondary and tertiary structure), accessing the various structural aspects of protein chemistry is a vibrant research area. Likewise, the properties and utility of proteins in applications such as catalysis and molecular recognition are being emulated in the laboratory to great effect. Rather than provide an exhaustive review on any one of these topics, this article seeks to highlight the common thread among them, encouraging discussion and collaboration that will result in the next generation of smart materials with advanced structure and function. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 191–206     

Heteroannelated (+)-muricatacin mimics: synthesis, antiproliferative properties and structure-activity relationships

Six new (+)-muricatacin mimics bearing a furano-furanone core have been synthesized and their in vitro antiproliferative activity was evaluated against a panel of human tumour cell lines. A straightforward total synthesis of (+)-muricatacin (1) from d-xylose is disclosed providing a sample of 1 that served as a positive control in antitumour assays. All new compounds showed diverse antiproliferative effects against human malignant cell lines, but were devoid of any significant cytotoxicity towards the normal foetal lung fibroblasts (MRC-5). Additionally, the most of (+)-muricatacin analogues show selective cytotoxicities towards certain cancer cell lines, whereas only two of six analogues are broadly toxic against all cell lines under evaluation. A SAR study reveals the structural features that may be beneficial for the antiproliferative activity of these lactones. These include the absolute stereochemistry, introduction of a THF ring, interchange of the O₈ ether functionality and the C₈ methylene group in the side chain of muricatacin oxa analogues, as well as the one- or two-carbon homologation of the side chain in both 3 and 6.     

Boosting the Peroxidase‐like Activity of Cobalt Ions by Amino Acid‐based Biological Species and Its Applications

Enzyme mimics have been widely used as alternatives to natural enzymes, owing to their high stability and low cost. However, the activity and atom economy of enzyme mimics still need to be improved. Herein, we report the boosting effects of amino acids, peptides and proteins on the peroxidase‐like activity of Co²⁺. Among 20 amino acids, tryptophan (Trp) enhanced the activity of Co²⁺ approximately 8 times and was identified as the best stimulator. The study revealed the synergy of amino acids‐based species and HCO₃^? for efficient catalysis. Co²⁺ is proposed to bind simultaneously to HCO₃^? and Trp, and to form a ternary catalyst which facilitates the generation of reactive oxygen species. Based on the selective boosting by Trp, a simple and low‐cost Co²⁺ sensor with high sensitivity was developed, which showed a linear range of 10–300 μM and a limit of detection of 0.4 μM for Co²⁺.     

Synergistic Effect of Polyoxometalate and Single Walled Carbon Nanotubes on Peroxidase‐like Mimics and Highly Sensitive Electrochemical Detection of Hydrogen Peroxide

A novel Keggin‐type metatungstate hybrid POMs ((APy)₆[H₂W₁₂O₄₀])/carboxylic acid functionalized single‐walled carbon nanotube based amperometric sensing platform was successfully constructed for the sensitive detection of hydrogen peroxide. A simple and reliable procedure was implemented for the synthesis of new composite materials obtained by the covalent grafting of (APy)₆[H₂W₁₂O₄₀] onto the surface of (SWCNT‐COOH). The synergistic effect of single walled carbon nanotubes on the electrochemical behavior of (APy)₆[H₂W₁₂O₄₀] was evidenced through the increase of the oxidation and reduction peaks of the polyoxometalate. The sensitivity of hydrogen peroxide detection was increased by a factor of 38.5 in presence of SWCNTs, showing their high influence on peroxidase‐like mimics of (APy)₆[H₂W₁₂O₄₀]. The detection limit, the response time, the repeatability and the shelf lifetime were respectively 0.4 μM, 10 s, <4%, 60 days.     

基于金属卟啉2DMOFs仿酶催化的过氧化氢比色法检测

以四（4-羧苯基）铁卟啉（FeTCPP）作为有机配体,铜离子作为金属节点,利用溶剂热法制备了双金属Cu-FeTCPP金属有机骨架（MOFs）材料,并采用表面活性剂辅助法合成了二维纳米片（Cu-FeTCPP 2DMOFs）.该纳米片呈超薄的纳米结构,与三维块体结构（3DMOFs）相比具有更大的比表面积.基于Cu-FeTCPP 2DMOFs的仿酶特性,将其用于催化过氧化氢（H₂O₂）氧化底物3,3',5,5'-四甲基联苯胺（TMB）显色,根据显色产物吸光度与H₂O₂浓度之间的正比关系实现了对H₂O₂的测定.经稳态动力学分析发现,底物相同时该纳米片的米氏常数K_m均比Cu-FeTCPP 3DMOFs的K_m小,表明纳米片与底物之间有更好的亲和力,这归因于二维结构大的比表面积和较多易接近的活性位点.基于Cu-FeTCPP 2DMOFs构建的比色检测方法在优化条件下对H₂O₂的线性检测范围为3~1000 μmol/L,检出限为2.08 μmol/L,在水体中H₂O₂的检测方面具有良好的应用前景.     

Novel 2-aryl-3,4,5-trihydroxypiperidines： Synthesis and glycosidase inhibition

Three pairs of novel 2-aryl-3,4,5-trihydroxypiperidines （6-8 and their enantiomers）, the piperidine analogues of the pyrrolidine alkaloids radicamine A and radicamine B, were prepared from six- membered cyclic nitrones through a concise two-step procedure, i.e., Grignard reagent addition and deprotection. These novel polyhydroxylated piperidine iminosugars were assayed against 10 types of enzymes. Only compound 8 exhibited weak inhibition （IC50 1080 μmol/L） against β-galactosidase from rat intestinal lactases.     

两亲分子组装介导的化学反应及相关生命起源化学

化学反应会受其所处微环境影响,因此不同分子间相互作用对反应进程的调控不容忽视.水溶液作为优良的反应介质,其应用常受到反应物溶解性差的限制.在水溶液中引入胶束或囊泡等两亲分子组装,可在一定程度上克服这种不足.这些均匀分散的动态组装,提供了有别于本体水溶液的微环境,以非共价的方式,将单体结合到其极性表面或疏水内核.通过加速...