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Chemical Science

George M Burslem, Hannah F Kyle, Adam Nelson, Thomas A Edwards, Andrew J Wilson
The modulation of protein-protein interactions (PPIs) represents a major challenge in modern chemical biology. Current approaches (e.g. high-throughput screening, computer aided ligand design) are recognised as having limitations in terms of identification of hit matter. Considerable success has been achieved in terms of developing new approaches to PPI modulator discovery using the p53/hDM2 and Bcl-2 family of PPIs. However these important targets in oncology might be considered as "low-hanging-fruit". Hypoxia inducible factor (HIF) is an emerging, but not yet fully validated target for cancer chemotherapy...
June 1, 2017: Chemical Science
Simon Grabowsky, Alessandro Genoni, Hans-Beat Bürgi
Approximate wavefunctions can be improved by constraining them to reproduce observations derived from diffraction and scattering experiments. Conversely, charge density models, incorporating electron-density distributions, atomic positions and atomic motion, can be improved by supplementing diffraction experiments with quantum chemically calculated, tailor-made electron densities (form factors). In both cases quantum chemistry and diffraction/scattering experiments are combined into a single, integrated tool...
June 1, 2017: Chemical Science
Gia L Hoang, James M Takacs
The rhodium-catalyzed, directed catalytic asymmetric hydroboration of γ,δ-unsaturated amides affords a direct route to chiral acyclic secondary γ-borylated carbonyl derivatives in high enantiomeric purity. In contrast to a similar β-borylated amide derivative, the γ-borylated amide undergoes Suzuki-Miyaura cross-coupling with stereoretention. The utility of the boronic ester products is further illustrated by other stereospecific C-B bond transformations leading to γ-amino acid derivatives, 1,4-amino alcohols, and 5-substituted-γ-lactone and γ-lactam ring systems...
June 1, 2017: Chemical Science
Feriel Rekhroukh, Charlie Blons, Laura Estévez, Sonia Mallet-Ladeira, Karinne Miqueu, Abderrahmane Amgoune, Didier Bourissou
The synthesis and characterization of the first gold(iii)-arene complexes are described. Well-defined (P,C)-cyclometalated gold(iii)-aryl complexes were prepared and characterized by NMR spectroscopy. These complexes swiftly and cleanly reacted with norbornene and ethylene to provide cationic gold(iii)-alkyl complexes, in which the remote phenyl ring was η(2)-coordinated to gold. The interaction between the aromatic ring and the gold(iii) center was thoroughly analyzed by NMR spectroscopy, X-ray diffraction, and DFT calculations...
June 1, 2017: Chemical Science
Zhiqiang Mao, Hong Jiang, Zhen Li, Cheng Zhong, Wei Zhang, Zhihong Liu
In situ fluorescence imaging of nitric oxide (NO) is a powerful tool for studying the critical roles of NO in biological events. However, the selective imaging of NO is still a challenge because most currently available fluorescent probes rely on the o-phenylenediamine (OPD) recognition site, which reacts with both NO and some abundant reactive carbonyl species (RCS) (such as dehydroascorbic acid and methylglyoxal) and some reactive oxygen/nitrogen species (ROS/RNS). To address this problem, a new fluorescent probe, NCNO, based on the N-nitrosation of aromatic secondary amine was designed to bypass the RCS, ROS, and RNS interference...
June 1, 2017: Chemical Science
Alexander Johnson, Jeppe Madsen, Paul Chapman, Abdullah Alswieleh, Omed Al-Jaf, Peng Bao, Claire R Hurley, Michaël L Cartron, Stephen D Evans, Jamie K Hobbs, C Neil Hunter, Steven P Armes, Graham J Leggett
Binary polymer brush patterns were fabricated via photodeprotection of an aminosilane with a photo-cleavable nitrophenyl protecting group. UV exposure of the silane film through a mask yields micrometre-scale amine-terminated regions that can be derivatised to incorporate a bromine initiator to facilitate polymer brush growth via atom transfer radical polymerisation (ATRP). Atomic force microscopy (AFM) and imaging secondary ion mass spectrometry (SIMS) confirm that relatively thick brushes can be grown with high spatial confinement...
June 1, 2017: Chemical Science
Chaoxing Liu, Yafen Wang, Xiong Zhang, Fan Wu, Wei Yang, Guangrong Zou, Qian Yao, Jiaqi Wang, Yuqi Chen, Shaoru Wang, Xiang Zhou
Recently, the detection of natural thymine modified 5-formyluracil has attracted widespread attention. Herein, we introduce a new insight into designing reagents for both the selective biotin enrichment and fluorogenic labelling of 5-formyluracil in DNA. Biotinylated o-phenylenediamine directly tethered to naphthalimide can switch on 5-formyluracil, under physiological conditions, which can then be used in cell imaging after exposure to γ-irradiation. In addition, its labelling property caused the polymerase extension to stop in the 5-formyluracil site, which gave us more information than the fluorescence did itself...
June 1, 2017: Chemical Science
Sven Tobisch
An in-depth computational mechanistic probe of the CuH-mediated hydroamination of internal arylalkynes with an archetype hydroxylamine ester and hydrosilane by a (Xantphos)CuH catalyst (Xantphos ≡ {P^P} ≡ 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) is presented. This first comprehensive computational study of the CuH-mediated electrophilic alkyne hydroamination has identified the most accessible pathway for the rival avenues for direct and reductive hydroamination. The mechanistic picture derived from smooth energy profiles obtained by employing a reliable computational protocol applied to a realistic catalyst model conforms to all available experimental data...
June 1, 2017: Chemical Science
Lili Wang, Yaping Feng, Yi Zhou, Meijuan Jia, Guojie Wang, Wei Guo, Lei Jiang
The bottom-up assembly of ion-channel-mimetic nanofluidic devices and materials with two-dimensional (2D) nano-building blocks paves a straightforward way towards the real-world applications of the novel transport phenomena on a nano- or sub-nanoscale. One immediate challenge is to provide the 2D nanofluidic systems with adaptive responsibilities and asymmetric ion transport characteristics. Herein, we introduce a facile and general strategy to provide a graphene-oxide-based 2D nanofluidic system with photo-switchable ionic current rectification (ICR)...
June 1, 2017: Chemical Science
Michael S Inkpen, Yann R Leroux, Philippe Hapiot, Luis M Campos, Latha Venkataraman
Whilst most studies in single-molecule electronics involve components first synthesized ex situ, there is also great potential in exploiting chemical transformations to prepare devices in situ. Here, as a first step towards this goal, we conduct reversible reactions on monolayers to make and break covalent bonds between alkanes of different lengths, then measure the conductance of these molecules connected between electrodes using the scanning tunneling microscopy-based break junction (STM-BJ) method. In doing so, we develop the critical methodology required for assembling and disassembling surface-bound single-molecule circuits...
June 1, 2017: Chemical Science
Bifan Chen, Leekyoung Hwang, William Ochowicz, Ziqing Lin, Tania M Guardado-Alvarez, Wenxuan Cai, Lichen Xiu, Kunal Dani, Cyrus Colah, Song Jin, Ying Ge
Phosphorylation plays pivotal roles in cellular processes and dysregulated phosphorylation is considered as an underlying mechanism in many human diseases. Top-down mass spectrometry (MS) analyzes intact proteins and provides a comprehensive analysis of protein phosphorylation. However, top-down MS-based phosphoproteomics is challenging due to the difficulty in enriching low abundance intact phosphoproteins as well as separating and detecting the enriched phosphoproteins from complex mixtures. Herein, we have designed and synthesized the next generation functionalized superparamagnetic cobalt ferrite (CoFe2O4) nanoparticles (NPs), and have further developed a top-down phosphoproteomics strategy coupling phosphoprotein enrichment enabled by the functionalized CoFe2O4 NPs with online liquid chromatography (LC)/MS/MS for comprehensive characterization of phosphoproteins...
June 1, 2017: Chemical Science
Tom Podewin, Johannes Broichhagen, Christina Frost, Dieter Groneberg, Julia Ast, Helena Meyer-Berg, Nicholas H F Fine, Andreas Friebe, Martin Zacharias, David J Hodson, Dirk Trauner, Anja Hoffmann-Röder
The optical control over biological function with small photoswitchable molecules has gathered significant attention in the last decade. Herein, we describe the design and synthesis of a small library of photoswitchable peptidomimetics based upon human atrial natriuretic peptide (ANP), in which the photochromic amino acid [3-(3-aminomethyl)phenylazo]phenylacetic acid (AMPP) is incorporated into the peptide backbone. The endogeneous hormone ANP signals via the natriuretic peptide receptor A (NPR-A) through raising intracellular cGMP concentrations, and is involved in blood pressure regulation and sodium homeostasis, as well as lipid metabolism and pancreatic function...
June 1, 2017: Chemical Science
Yuchuan Wang, Ligang Hu, Feng Xu, Quan Quan, Yau-Tsz Lai, Wei Xia, Ya Yang, Yuen-Yan Chang, Xinming Yang, Zhifang Chai, Junwen Wang, Ivan K Chu, Hongyan Li, Hongzhe Sun
Bismuth drugs, despite being clinically used for decades, surprisingly remain in use and effective for the treatment of Helicobacter pylori infection, even for resistant strains when co-administrated with antibiotics. However, the molecular mechanisms underlying the clinically sustained susceptibility of H. pylori to bismuth drugs remain elusive. Herein, we report that integration of in-house metalloproteomics and quantitative proteomics allows comprehensive uncovering of the bismuth-associated proteomes, including 63 bismuth-binding and 119 bismuth-regulated proteins from Helicobacter pylori, with over 60% being annotated with catalytic functions...
June 1, 2017: Chemical Science
Silvia Alonso-de Castro, Emmanuel Ruggiero, Ane Ruiz-de-Angulo, Elixabete Rezabal, Juan C Mareque-Rivas, Xabier Lopez, Fernando López-Gallego, Luca Salassa
Encouraging developments demonstrate that few transition metal and organometallic catalysts can operate in a bioorthogonal fashion and promote non-natural chemistry in living systems by minimizing undesired side reactions with cellular components. These catalytic processes have potential for applications in medicinal chemistry and chemical biology. However, the stringent conditions of the cell environment severely limit the number of accessible metal catalysts and exogenous reactions. Herein, we report an unorthodox approach and a new type of bioorthogonal catalytic reaction, in which a metal complex is an unconventional substrate and an exogenous biological molecule acts as a catalyst...
June 1, 2017: Chemical Science
Zhongwei Hu, Lasse Jensen
The two-photon absorption (TPA) cross-sections of small thiolate-protected gold clusters have been shown to be much larger than typical small organic molecules. In comparison with larger nanoparticles, their TPA cross-sections per gold atom are also found to be larger. Theoretical simulations have suggested that the large enhancement of these TPA cross-sections comes from a one-photon double-resonance mechanism. However, it remains difficult to simulate TPA cross-sections of thiolate-protected gold clusters due to their large system size and a high density of states...
June 1, 2017: Chemical Science
Yong Cheng, Chunli Sun, Xiaowen Ou, Bifeng Liu, Xiaoding Lou, Fan Xia
Precisely targeted transportation of a long-term tracing regent to a nucleus with low toxicity is one of the most challenging concerns in revealing cancer cell behaviors. Here, we report a dual-targeted peptide-conjugated multifunctional fluorescent probe (cNGR-CPP-NLS-RGD-PyTPE, TCNTP) with aggregation-induced emission (AIE) characteristic, for efficient nucleus-specific imaging and long-term and low-toxicity tracing of cancer cells. TCNTP mainly consists of two components: one is a functionalized combinatorial peptide (TCNT) containing two targeted peptides (cNGR and RGD), a cell-penetrating peptide (CPP) and a nuclear localization signal (NLS), which can specifically bind to a cell surface and effectively enter into the nucleus; the other one is an AIE-active tetraphenylethene derivative (PyTPE, a typical AIEgen) as fluorescence imaging reagent...
June 1, 2017: Chemical Science
Azhar Mahmood, Nanhong Xie, Muhammad Aizaz Ud Din, Faisal Saleem, Haifeng Lin, Xun Wang
Mechanistic control is a powerful means for manufacturing specific shapes of metal nanostructures and optimizing their performance in a variety of applications. Thus, we successfully synthesized multimetallic nanoplates (PtAgBiCo and PtAgBi) by combining the concepts of crystal symmetry, oxidative etching and seed ratio, and tuned their activity, stability and methanol tolerance, as well as Pt utilization, for the oxygen reduction reaction in direct methanol fuel cells. Systematic studies reveal that the formation of PtAgBiCo triangular nanoplates with a high morphological yield (>90%) can be achieved by crystallinity alteration, while electrochemical measurements indicate that the PtAgBiCo nanoplates have superior electrocatalytic activity towards the oxygen reduction reaction...
June 1, 2017: Chemical Science
Wen Liu, Yingying Mi, Zhe Weng, Yiren Zhong, Zishan Wu, Hailiang Wang
Dendrite growth and low coulombic efficiency are two major factors that limit the utilization of Li metal electrodes in future generations of high-energy-density rechargeable batteries. This article reports the first study on metal-organic framework (MOF) materials for boosting the electrochemical performance of Li metal electrodes and demonstrates the power of molecular-structure functionalization for realizing desirable ion transport and Li metal nucleation and growth. We show that dendrite-free dense Li deposition and stable Li plating/stripping cycling with high coulombic efficiency are enabled by modifying a commercial polypropylene separator with a titanium-based MOF (NH2-MIL-125(Ti)) material...
June 1, 2017: Chemical Science
Babu Sudhamalla, Debasis Dey, Megan Breski, Tiffany Nguyen, Kabirul Islam
Chemical modifications on DNA, RNA and histones are recognized by an array of 'reader' modules to regulate transcriptional programming and cell fate. However, identification of reader-specific interacting partners in a dynamic cellular environment remains a significant challenge. Herein, we report a chemoproteomic approach termed 'interaction-based protein profiling' (IBPP) to characterize novel interacting partners of potentially any reader protein. IBPP harnesses a photosensitive amino acid introduced into the hydrophobic pocket of a reader module to crosslink and enrich transient interacting partners that are inaccessible to traditional methods...
June 1, 2017: Chemical Science
Ru-Ru Gao, Tian-Ming Yao, Xiao-Yan Lv, Yan-Yan Zhu, Yi-Wei Zhang, Shuo Shi
To create sophisticated molecular logic circuits from scratch, you may not believe how common the building blocks can be and how diverse and powerful such circuits can be when scaled up. Using the two simple building blocks of G-quadruplex and silver nanoclusters (Ag NCs), we experimentally construct a series of multifunctional, label-free, and multi-output logic circuits to perform nonarithmetic functions: a 1-to-2 decoder, a 4-to-2 encoder, an 8-to-3 encoder, dual transfer gates, a 2 : 1 multiplexer, and a 1 : 2 demultiplexer...
June 1, 2017: Chemical Science
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