jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Cosimo Kropp | Kristina Straub | Mona Linde | Patrick Babinger
Source: Protein Science (article, 2020-12-20)
Field: Materials Science — Materials Chemistry

Hexamerization and thermostability emerged very early during geranylgeranylglyceryl phosphate synthase evolution A large number of archaea live in hyperthermophilic environments. In consequence, their proteins need to adopt to these harsh conditions, including the enzymes that catalyze the synthesis of their membrane ether lipids. The enzyme that catalyzes the formation of the first ether bond in these lipids, geranylgeranylglyceryl phosphate synthase (GGGPS), exists as a hexamer in many hyperthermophilic archaea, and a recent study suggested that hexamerization serves for a fine-tuning of the flexibility - stability trade-off under hyperthermophilic conditions. We have recently reconstructed the sequences of ancestral group II GGGPS enzymes and now present a detailed biochemical characterization of nine of these predecessors, which allowed us to trace back the evolution of hexameric GGGPS and to draw conclusions about the properties of extant GGGPS branches that were not accessible to experiments up to now. Almost all ancestral GGGPS proteins formed hexamers, which demonstrates that hexamerization is even more widespread among the GGGPS family than previously assumed. Furthermore, all experimentally studied ancestral proteins showed high thermostability. Our results indicate that the hexameric oligomerization state and thermostability were present very early during the evolution of group II GGGPS, while the fine tuning of the flexibility - stability trade-off developed very late, independent of the emergence of hexamerization. Thermostability ; Archaea ; Hyperthermophile ; Random hexamer ; Extant taxon ; Biology ; Enzyme ; Pyrococcus furiosus ; ATP synthase ; Chemistry ; Biochemistry ; Evolutionary biology ; Gene Enzyme Structure and Function ; RNA and protein synthesis mechanisms ; RNA modifications and cancer
Authors: Zhongqun Zhou | Shenye Chen | Weichen Li | Junjie He | Caili Yu | Faai Zhang
Source: Macromolecular Materials and Engineering (article, 2020-11-09)
Field: Materials Science — Polymers and Plastics

Mechanically Stable Dynamic Urea Bond‐Based Crosslinked Polymer Blend with Tunable Self‐Healable and Physical Properties Abstract Polymer networks crosslinked by reversible noncovalent crosslinks have been applied in self‐healing and recyclable sustainable materials but result in limited mechanical strength. Herein, a crosslinked polymer blend that is based on a urethane–arcylate system with a combination of reversibly noncovalent intrachain and interchain hydrogen bonds and dynamically covalent urea bonds is developed through facile in situ photo‐induced copolymerization. An essential step is the introduction of a flexibly dynamic crosslinker bearing robustly hindered urea bonds and urethane–urea structures into the network, which endows the dynamic network with a synergy of mechanical robustness and desirable self‐healing ability. The dynamic networks exhibit rapid self‐healing at mild conditions (70 °C, 30 min), extreme toughness (≈34.76 MJ m −3 ), high tensile strength (≈7.78 MPa), superior stretchability (≈932%), long‐term stability, recyclability, and weldability. More importantly, the mechanical and self‐healing properties of the resultant materials can be fine‐tuned by adjusting the dynamic crosslinker content. These superior properties are attributed to the dynamic reversibility of hydrogen bonds and urea bonds as monitored by rheological tests. The extremely facile fabrication approach and superior properties of the resulting self‐healing polymers can find applications in sustainable smart materials and self‐healing conductive sensors. Materials science ; Toughness ; Self-healing material ; Self-healing ; Polymer ; Hydrogen bond ; Copolymer ; Ultimate tensile strength ; Smart polymer ; Composite material ; Covalent bond ; Chemical engineering ; Molecule ; Organic chemistry Polymer composites and self-healing ; Polydiacetylene-based materials and applications ; Advanced Sensor and Energy Harvesting Materials
Authors: Xiangquan Hu | Sisi Feng | Jialei Du | Li Shao | Jinxin Lang | Chen Zhang | Steven P. Kelley | Jian Lin | Scott J. Dalgarno | David A. Atwood | Jerry L. Atwood
Source: Chemical Science (article, 2020-01-01)
Field: Chemistry — Organic Chemistry

Controlled hierarchical self-assembly of networked coordination nanocapsules<i>via</i>the use of molecular chaperones Supramolecular chaperones play an important role in directing the assembly of multiple protein subunits and redox-active metal ions into precise, complex and functional quaternary structures. Here we report that hydroxyl tailed <i>C</i>-alkylpyrogallol[4]arene ligands and redox-active Mn<sup>II</sup> ions, with the assistance of proline chaperone molecules, can assemble into two-dimensional (2D) and/or three-dimensional (3D) networked nanocapsules. Dimensionality is controlled by coordination between the exterior of nanocapsule subunits, and endohedral functionalization within the 2D system is achieved <i>via</i> chaperone guest encapsulation. The tailoring of surface properties of nanocapsules <i>via</i> coordination chemistry is also shown as an effective method for the fine-tuning magnetic properties, and electrochemical and spectroscopic studies support that the nanocapsule is an effective homogeneous water-oxidation electrocatalyst, operating at pH 6.07 with an exceptionally low overpotential of 368 mV. Nanocapsules ; Nanotechnology ; Self-assembly ; Coordination complex ; Chemistry ; Computer science ; Materials science ; Nanoparticle Supramolecular Chemistry and Complexes ; Supramolecular Self-Assembly in Materials ; Crystallography and molecular interactions
Authors: Han Vinh Huynh | Jeroen T. Vossen
Source: Inorganic Chemistry (article, 2020-08-11)
Field: Chemistry — Organic Chemistry

Donor Strength Determination of Pyridinylidene-amide Ligands using Their Palladium–NHC Complexes Pyridinylidene-amides (PYAs) are a relatively new type of N-donor ligands that can exist in three isomeric forms and adopt various resonance structures. This makes them electronically flexible, and in order to evaluate their electronic profile using the Huynh electronic parameter (HEP), seven structurally diverse mixed <i>N</i>-heterocyclic carbenes (NHCs)/PYA palladium complexes of the type <i>trans</i>-[PdBr<sub>2</sub>(<sup><i>i</i></sup>Pr<sub>2</sub>-bimy)(PYA)] were prepared and fully characterized by various spectroscopic and spectrometric methods. This study shows that PYAs are among the strongest, formally neutral N-donors, but they are still weaker than phosphines and organometallic ligands such as NHCs. Notably, the donating abilities of isomeric PYAs are distinct and can be further fine-tuned by the choice of two substituents making them structurally and electronically versatile. These characteristics and the ease of their preparation hold promise for a wide applicability in coordination chemistry. Chemistry ; Palladium ; Amide ; Organometallic chemistry ; Resonance (particle physics) ; Stereochemistry ; Combinatorial chemistry ; Organic chemistry ; Catalysis N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Organometallic Complex Synthesis and Catalysis
Authors: Marek Wilhelm | Margret Giesen | Tomáš Duchoň | Marco Moors | David N. Mueller | Johanna Hackl | Christoph Baeumer | Mai Hussein Hamed | Lei Cao | Hengbo Zhang | O. Petracic | Maria Glöß | S. Cramm | Slavomír Nemšák | C. Wiemann | Regina Dittmann | Claus M. Schneider | Martina Müller
Source: APL Materials (article, 2020-11-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Photoemission electron microscopy of magneto-ionic effects in La0.7Sr0.3MnO3 Magneto-ionic control of magnetism is a promising route toward the realization of non-volatile memory and memristive devices. Magneto-ionic oxides are particularly interesting for this purpose, exhibiting magnetic switching coupled to resistive switching, with the latter emerging as a perturbation of the oxygen vacancy concentration. Here, we report on electric-field-induced magnetic switching in a La0.7Sr0.3MnO3 (LSMO) thin film. Correlating magnetic and chemical information via photoemission electron microscopy, we show that applying a positive voltage perpendicular to the film surface of LSMO results in the change in the valence of the Mn ions accompanied by a metal-to-insulator transition and a loss of magnetic ordering. Importantly, we demonstrate that the voltage amplitude provides granular control of the phenomena, enabling fine-tuning of the surface electronic structure. Our study provides valuable insight into the switching capabilities of LSMO that can be utilized in magneto-ionic devices. Materials science ; Ionic bonding ; Magnetism ; Condensed matter physics ; Photoemission electron microscopy ; Ferromagnetism ; Valence (chemistry) ; Nanotechnology ; Chemical physics ; Ion ; Electron microscope ; Chemistry ; Optics Magnetic and transport properties of perovskites and related materials ; Multiferroics and related materials ; Electronic and Structural Properties of Oxides
Authors: Keshav Kumar | Ralf M. Schweiggert | Claus‐Dieter Patz
Source: Analytical Methods (article, 2020-01-01)
Field: Chemistry — Analytical Chemistry

Introducing a novel procedure for peak alignment in one-dimensional <sup>1</sup>H-NMR spectroscopy: a prerequisite for chemometric analyses of wine samples Shifted peak positions in 1H-nuclear magnetic resonance (1H-NMR) spectroscopy of wine samples are inevitably occurring mainly due to variations in the sample matrix, which consists of ethanol, glycerol, carbohydrates, acids, phenolic compounds, minerals, and aroma compounds. Slight variations in pH during sample preparation or fluctuations in instrumental factors may contribute to shifted peak positions that need to be corrected before subjecting the NMR data to chemometric techniques to ensure samples are compared on the correct chemical shift scale. In the current work, a novel procedure for correcting 1H-NMR spectroscopy peak positions was developed by mapping of the raw NMR spectra on a common chemical shift axis using a simple interpolation approach. The mapping allowed a substantial correction of peak positions and subsequently reduced the computational burden in further spectral processing. Fine-tuning of the peak alignments was carried out efficiently by interval-wisely applying the correlation optimized warping (COW) algorithm. Our preceding mapping approach enabled the use of substantially simpler alignment parameters of the COW algorithm, thereby accelerating the whole peak alignment process. The developed procedure may also be suitable for facilitating NMR analyses of other sample types, such as agricultural, clinical or pharmaceutical samples in targeted or untargeted analytical approaches. Nuclear magnetic resonance spectroscopy ; Spectral line ; Chemistry ; Wine ; Analytical Chemistry (journal) ; Two-dimensional nuclear magnetic resonance spectroscopy ; NMR spectra database ; Spectroscopy ; Chromatography ; Physics ; Stereochemistry Spectroscopy and Chemometric Analyses ; Metabolomics and Mass Spectrometry Studies ; Advanced Chemical Sensor Technologies
Authors: Fang‐Yu Ren | Pengfei Ji
Source: Catalysts (article, 2020-12-09)
Field: Chemistry — Inorganic Chemistry

Recent Advances in the Application of Metal–Organic Frameworks for Polymerization and Oligomerization Reactions Polymers have become one of the major types of materials that are essential in our daily life. The controlled synthesis of value-added polymers with unique mechanical and chemical properties have attracted broad research interest. Metal–organic framework (MOF) is a class of porous material with immense structural diversity which offers unique advantages for catalyzing polymerization and oligomerization reactions including the uniformity of the catalytic active site, and the templating effect of the nano-sized channels. We summarized in this review the important recent progress in the field of MOF-catalyzed and MOF-templated polymerizations, to reveal the chemical principle and structural aspects of these systems and hope to inspire the future design of novel polymerization systems with improved activity and specificity. Polymerization ; Nanotechnology ; Materials science ; Polymer Metal-Organic Frameworks: Synthesis and Applications ; Covalent Organic Framework Applications ; Carbon dioxide utilization in catalysis
Authors: Emanuela Calcio Gaudino | Elisa Acciardo | Silvia Tabasso | Maela Manzoli | Giancarlo Cravotto | Rajender S. Varma
Source: Molecules (article, 2020-01-19)
Field: Chemistry — Organic Chemistry

Cross-Linked Cyclodextrins Bimetallic Nanocatalysts: Applications in Microwave-Assisted Reductive Aminations The optimization of sustainable protocols for reductive amination has been a lingering challenge in green synthesis. In this context, a comparative study of different metal-loaded cross-linked cyclodextrins (CDs) were examined for the microwave (MW)-assisted reductive amination of aldehydes and ketones using either H<sub>2</sub> or formic acid as a hydrogen source. The Pd/Cu heterogeneous nanocatalyst based on Pd (II) and Cu (I) salts embedded in a β-CD network was the most efficient in terms of yield and selectivity attained. In addition, the polymeric cross-linking avoided metal leaching, thus enhancing the process sustainability; good yields were realized using benzylamine under H<sub>2</sub>. These interesting findings were then applied to the MW-assisted one-pot synthesis of secondary amines via a tandem reductive amination of benzaldehyde with nitroaromatics under H<sub>2</sub> pressure. The formation of a Cu<sub>x</sub>Pd<sub>y</sub> alloy under reaction conditions was discerned, and a synergic effect due to the cooperation between Cu and Pd has been hypothesized. During the reaction, the system worked as a bifunctional nanocatalyst wherein the Pd sites facilitate the reduction of nitro compounds, while the Cu species promote the subsequent imine hydrogenation affording structurally diverse secondary amines with high yields. Reductive amination ; Chemistry ; Bifunctional ; Benzylamine ; Dehydrogenation ; Microwave chemistry ; Imine ; Bimetallic strip ; Amination ; Benzaldehyde ; Catalysis ; Nanomaterial-based catalyst ; Formic acid ; Organic chemistry ; Combinatorial chemistry Nanomaterials for catalytic reactions ; Asymmetric Hydrogenation and Catalysis ; Catalytic Cross-Coupling Reactions
Authors: Katsuya Shimizu | Arisa Okuma | Shiho Katsumi | Fuyuki Ito | Seiya Kobatake
Source: Dyes and Pigments (article, 2020-02-14)
Field: Materials Science — Materials Chemistry

Synthesis and multicolor emission properties of polystyrene with difluoroboron avobenzone complexes at side chains Polymer ; Fluorescence ; Polystyrene ; Copolymer ; Tetrahydrofuran ; Monomer ; Emission spectrum ; Photochemistry ; Amorphous solid ; Materials science ; Intermolecular force ; Absorption (acoustics) ; Analytical Chemistry (journal) ; Polymer chemistry ; Chemistry ; Molecule ; Spectral line ; Crystallography ; Organic chemistry ; Optics Luminescence and Fluorescent Materials ; Organic Light-Emitting Diodes Research ; Conducting polymers and applications
Authors: Tianxiang Chen | Qi Xue | Kwan‐Chee Leung | Tsz Woon Benedict Lo
Source: Chemistry - An Asian Journal (review, 2020-04-28)
Field: Materials Science — Materials Chemistry

Recent Advances of Precise Cu Nanoclusters in Microporous Materials This minireview highlights some recent advances in the rational design of precise Cu nanoclusters supported on microporous materials, including zeolites and metal-organic frameworks. The development of comprehensive characterisation techniques enables scientists to elucidate the structure-activity relationship of these catalysts, which aids the subsequent engineering of more superior catalytic systems at an atomistic perspective. Microporous material ; Nanoclusters ; Nanotechnology ; Rational design ; Materials science ; Catalysis ; Chemistry ; Organic chemistry Nanocluster Synthesis and Applications ; Metal-Organic Frameworks: Synthesis and Applications ; Catalytic Processes in Materials Science
Authors: Max Roemer | Vinícius R. Gonçales | Sinead T. Keaveney | Indrek Pernik | Jiaxin Lian | James E. Downes | J. Justin Gooding | Barbara A. Messerle
Source: Catalysis Science & Technology (article, 2020-12-30)
Field: Chemistry — Inorganic Chemistry

Carbon supported hybrid catalysts for controlled product selectivity in the hydrosilylation of alkynes A series of Rh- and Ir-hybrid catalysts with varying tether lengths has been prepared by immobilization of Rh<sup>I</sup>, Rh<sup>III</sup> and Ir<sup>III</sup> complexes on carbon black, and applied in the hydrosilylation of alkynes. Hydrosilylation ; Catalysis ; Selectivity ; Carbon fibers ; Chemistry ; Carbon black ; Product (mathematics) ; Organic chemistry ; Medicinal chemistry ; Polymer chemistry ; Materials science ; Composite material ; Composite number Asymmetric Hydrogenation and Catalysis ; Catalytic Cross-Coupling Reactions ; Organoboron and organosilicon chemistry
Authors: Christopher M. A. Parlett | Lee J. Durndell | Mark A. Isaacs | Xiaotong Liu | Chunfei Wu
Source: Topics in Catalysis (article, 2020-05-06)
Field: Materials Science — Materials Chemistry

Ethanol Steam Reforming for Hydrogen Production Over Hierarchical Macroporous Mesoporous SBA-15 Supported Nickel Nanoparticles Abstract The influence of complementary macropores, present in hierarchical macroporous mesoporous SBA-15, on the performance of supported Ni nanoparticles for ethanol steam reforming has been investigated. The increased open nature of the architecture, afforded through the incorporation of the secondary macropore network, enables superior metal dispersion. This, in turn, enhances catalytic hydrogen production performance through the generation of a greater density of active sites. Mesoporous material ; Macropore ; Catalysis ; Hydrogen production ; Steam reforming ; Chemical engineering ; Nickel ; Nanoparticle ; Ethanol ; Materials science ; Hydrogen ; Nanotechnology ; Chemistry ; Organic chemistry ; Metallurgy Catalytic Processes in Materials Science ; Catalysis and Hydrodesulfurization Studies ; Catalysts for Methane Reforming
Authors: Bjoern Bielec | Isabella Poetsch | Esra Ahmed | Petra Heffeter | Bernhard K. Keppler | Christian R. Kowol
Source: Molecules (article, 2020-03-04)
Field: Chemistry — Organic Chemistry

Reactive Oxygen Species (ROS)-Sensitive Prodrugs of the Tyrosine Kinase Inhibitor Crizotinib Tyrosine kinase inhibitors revolutionized cancer therapy but still evoke strong adverse effects that can dramatically reduce patients' quality of life. One possibility to enhance drug safety is the exploitation of prodrug strategies to selectively activate a drug inside the tumor tissue. In this study, we designed a prodrug strategy for the approved c-MET, ALK, and ROS1 tyrosine kinase inhibitor crizotinib. Therefore, a boronic-acid trigger moiety was attached to the 2-aminopyridine group of crizotinib, which is a crucial position for target kinase binding. The influence of the modifications on the c-MET- and ALK-binding ability was investigated by docking studies, and the strongly reduced interactions could be confirmed by cell-free kinase inhibition assay. Furthermore, the newly synthesized compounds were tested for their activation behavior with H<sub>2</sub>O<sub>2</sub> and their stability in cell culture medium and serum. Finally, the biological activity of the prodrugs was investigated in three cancer cell lines and revealed a good correlation between activity and intrinsic H<sub>2</sub>O<sub>2</sub> levels of the cells for prodrug <b>A</b>. Furthermore, the activity of this prodrug was distinctly reduced in a non-malignant, c-MET expressing human lung fibroblast (HLF) cell line. Prodrug ; Crizotinib ; Tyrosine-kinase inhibitor ; Chemistry ; Kinase ; Tyrosine kinase ; Docking (animal) ; Pharmacology ; Cell culture ; Biochemistry ; Cancer research ; Lung cancer ; Cancer ; Signal transduction ; Biology ; Medicine ; Oncology ; Internal medicine Synthesis and biological activity ; Lung Cancer Treatments and Mutations ; Cancer therapeutics and mechanisms
Authors: Jonathan B. Grimm | Liangqi Xie | Jason C. Casler | Ronak Patel | Ariana N. Tkachuk | Heejun Choi | Jennifer Lippincott‐Schwartz | Timothy A. Brown | Benjamin S. Glick | Zhe Liu | Luke D. Lavis
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2020-08-17)
Field: Chemistry — Organic Chemistry

Deuteration improves small-molecule fluorophores ABSTRACT Fluorescence microscopy relies on dyes that absorb short-wavelength photons and emit longer-wavelength light. In addition to this fluorescence process, dyes can undergo other photochemical reactions that result in spectral shifts and irreversible photobleaching. Increases in brightness, ‘chromostability’, and photostability of fluorescent dyes are therefore crucial for advancing the frontier of bioimaging. Here, we describe a general approach to improve small-molecule fluorophores using deuteration. Incorporating deuterium into the alkylamino substituents of rhodamines and other dyes improves fluorescence quantum yield, inhibits photochemically induced spectral shifts, and slows irreparable photobleaching. These compounds are easily synthesized and show improved performance in cellular imaging experiments. Photobleaching ; Fluorescence ; Photochemistry ; Quantum yield ; Chemistry ; Molecule ; Fluorophore ; Autofluorescence ; Brightness ; Wavelength ; Materials science ; Optics ; Optoelectronics ; Physics Click Chemistry and Applications ; Advanced Fluorescence Microscopy Techniques ; Chemical Synthesis and Analysis
Authors: Ian R. Smith | Kyle Hess | Anna Bakhtina | Anthony S. Valente | Ricard A. Rodríguez‐Mias | Judit Villén
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2020-01-15)
Field: Chemistry — Spectroscopy

Identification of phosphosites that alter protein thermal stability ABSTRACT Proteomics has enabled the cataloguing of 100,000s of protein phosphorylation sites 1 , however we lack methods to systematically annotate their function. Phosphorylation has numerous biological functions, yet biochemically all involve changes in protein structure and interactions. These biochemical changes can be recapitulated by measuring the difference in stability between the protein and the phosphoprotein. Building on recent work, we present a method to infer phosphosite functionality by reliably measuring such differences at the proteomic scale. Phosphoprotein ; Phosphorylation ; Proteomics ; Identification (biology) ; Computational biology ; Protein phosphorylation ; Function (biology) ; Protein function ; Posttranslational modification ; Cell biology ; Biology ; Chemistry ; Biochemistry ; Protein kinase A ; Enzyme Advanced Proteomics Techniques and Applications ; Mass Spectrometry Techniques and Applications ; Protein Structure and Dynamics