pinecone/core-2020-05-10-deduplication huggingface dataset:
Collisional and Coulombic Unfolding of Gas‐Phase Proteins: High Correlation to Their Domain Structures in Solution

The three‐dimensional structures adopted by proteins are predicated by their many biological functions. Mass spectrometry has played a rapidly expanding role in protein structure discovery, enabling the generation of models for both proteins and their higher‐order assemblies. While important coursed‐grained insights have been generated, relatively few examples exist where mass spectrometry has been successfully applied to the characterization of protein tertiary structure. Here, we demonstrate that gas‐phase unfolding can be used to determine the number of autonomously folded domains within monomeric proteins. Our ion mobility‐mass spectrometry data highlight a strong, positive correlation between the number of protein unfolding transitions observed in the gas phase and the number of known domains within a group of sixteen proteins ranging from 8–78 kDa. This correlation and its potential uses for structural biology is discussed.     Entfaltung in der Gasphase  hilft bei der Bestimmung der Zahl selbständig gefalteter Domänen in monomeren Proteinen. Ionenbeweglichkeitsmassenspektrometrie belegt einen starken Zusammenhang zwischen der Zahl an Proteinentfaltungsübergängen in der Gasphase und der Zahl bekannter Domänen für sechzehn Proteine mit Massen von 8–78 kDa. CCS=Stoßquerschnitt
Tailoring Intermolecular Interactions for Efficient Room‐Temperature Phosphorescence from Purely Organic Materials in Amorphous Polymer Matrices

Herein we report a rational design strategy for tailoring intermolecular interactions to enhance room‐temperature phosphorescence from purely organic materials in amorphous matrices at ambient conditions. The built‐in strong halogen and hydrogen bonding between the newly developed phosphor G1 and the poly(vinyl alcohol) (PVA) matrix efficiently suppresses vibrational dissipation and thus enables bright room‐temperature phosphorescence (RTP) with quantum yields reaching 24 %. Furthermore, we found that modulation of the strength of halogen and hydrogen bonding in the G1–PVA system by water molecules produced unique reversible phosphorescence‐to‐fluorescence switching behavior. This unique system can be utilized as a ratiometric water sensor.     Wasserstoff‐ und Halogenbrücken  zwischen einem neuartigen Leuchtstoff und einer Polyvinylalkohol(PVA)‐Matrix führten zu einer hellen Raumtemperaturphosphoreszenz mit einer Quantenausbeute von 24 %. Die Modulation der Stärke der Halogen‐ und Wasserstoffbrücken in dem System aus rein organischem Leuchtstoff und PVA durch Wasser ermöglichte ein reversibles Schalten zwischen Phosphoreszenz (grün) und Fluoreszenz (blau; siehe Bild)
A De Novo Designed Metalloenzyme for the Hydration of CO 2

Protein design will ultimately allow for the creation of artificial enzymes with novel functions and unprecedented stability. To test our current mastery of nature’s approach to catalysis, a Zn II  metalloenzyme was prepared using de novo design. α 3 DH 3  folds into a stable single‐stranded three‐helix bundle and binds Zn II  with high affinity using His 3 O coordination. The resulting metalloenzyme catalyzes the hydration of CO 2  better than any small molecule model of carbonic anhydrase and with an efficiency within 1400‐fold of the fastest carbonic anhydrase isoform, CAII, and 11‐fold of CAIII.     Um Größenordnungen besser : Ein synthetisches Metalloenzym katalysiert die Hydratisierung von Kohlendioxid 1400‐mal effizienter als Carboanhydrase II, das selbst eines der effizientesten Enzyme überhaupt ist. Das entwickelte Zinkenzym übertrifft auch niedermolekulare Carboanhydrasemodelle. Bild: Zn violett, N dunkelblau, O rot, C cyan
Enantioselective Synthesis of Piperidines through the Formation of Chiral Mixed Phosphoric Acid Acetals: Experimental and Theoretical Studies

An enantioselective intramolecular chiral phosphoric acid‐catalyzed cyclization of unsaturated acetals has been utilized for the synthesis of functionalized chiral piperidines. The chiral enol ether products of these cyclizations undergo subsequent in situ enantioenrichment through acetalization of the minor enantiomer. A new computational reaction exploration method was utilized to elucidate the mechanism and stereoselectivity of this transformation. Rather than confirming the originally postulated cyclization proceeding directly through a vinyl oxocarbenium ion, simulations identified an alternative two‐step mechanism involving the formation of a mixed chiral phosphate acetal, which undergoes a concerted, asynchronous S N 2′‐like displacement to yield the product with stereoselectivity in agreement with experimental observations.     Eine enantioselektive Cyclisierung  ungesättigter Acetale mit einem chiralen Phosphorsäurekatalysator führt zu funktionalisierten Piperidinen. Die dabei erhaltenen chiralen Enolether durchlaufen anschließend in situ eine Enantiomerenanreicherung. Eine neue Rechenmethode wurde genutzt, um den Mechanismus und die Stereoselektivität dieser Transformation zu beleuchten. Cbz=Benzyloxycarbonyl;  S =Anreicherungsfaktor
Towards a Safe Lithium–Sulfur Battery with a Flame‐Inhibiting Electrolyte and a Sulfur‐Based Composite Cathode

Of the various beyond‐lithium‐ion batteries, lithium–sulfur (Li‐S) batteries were recently reported as possibly being the closest to market. However, its theoretically high energy density makes it potentially hazardous under conditions of abuse. Therefore, addressing the safety issues of Li‐S cells is necessary before they can be used in practical applications. Here, we report a concept to build a safe and highly efficient Li‐S battery with a flame‐inhibiting electrolyte and a sulfur‐based composite cathode. The flame retardant not only makes the carbonates nonflammable but also dramatically enhances the electrochemical performance of the sulfur‐based composite cathode, without an apparent capacity decline over 750 cycles, and with a capacity greater than 800 mA h −1  g −1 (sulfur) at a rate of 10 C.     Feuertaufe : Eine nichtentzündbare Schwefelkompositkathode zeigt eine stabile elektrochemische Aktivität über 750 Zyklen und eine Entladungskapazität von über 800 mA h −1  g −1 (Schwefel) mit einer Entladerate von 10 C in einem feuersicheren Elektrolyten. Der Elektrolyt wurde aus einem Phosphitadditiv erzeugt, das an Grenzflächenreaktionen an der Kathode teilnimmt und die Lithiumionendiffusion um das mehr als Zehnfache beschleunigt
Increasing Hybridization Rate and Sensitivity of Bead-Based Assays Using Isotachophoresis

マイクロ流体技術を用いた網羅的・高速DNA分析技術の開発に成功 -網羅的・短時間・高感度のバイオマーカ検出技術の確立に期待-. 京都大学プレスリリース. 2014-10-15.We present an electrokinetic technique to increase the reaction rate and sensitivity of bead-based assays. We use isotachophoresis (ITP) to preconcentrate and co-focus target molecules and beads into a single ITP zone. The process achieves rapid mixing, stirring, and strongly increases the binding reaction rate. We demonstrate our assay with quantitative detection of 24 nt single-stranded DNA over a dynamic range of three orders of magnitude and multiplexed detection of ten target species per sample. We show that ITP can achieve approximately the same sensitivity as a well-stirred standard reaction in 60-fold reduced reaction time (20 min versus 20 h). Alternately, compared to standard reaction times of 30 min, we show that 20 min ITP hybridization can achieve 5.3-fold higher sensitivity
Clotting activity of polyphosphate-functionalized silica nanoparticles

We present a silica nanoparticle (SNP) functionalized with polyphosphate (polyP) that accelerates the natural clotting process of the body. SNPs initiate the contact pathway of the blood-clotting system; short-chain polyP accelerates the common pathway by the rapid formation of thrombin, which enhances the overall blood-clotting system, both by accelerating fibrin generation and by facilitating the regulatory anticoagulation mechanisms essential for hemostasis. Analysis of the clotting properties of bare SNPs, bare polyP, and polyP-functionalized SNPs in plasma demonstrated that the attachment of polyP to SNPs to form polyP-SNPs creates a substantially enhanced synergistic effect that lowers clotting time and increases thrombin production at low concentrations. PolyP-SNP even retains its clotting function at ambient temperature. The polyP-SNP system has the potential to significantly improve trauma-treatment protocols and outcomes in hospital and prehospital settings
A Scalable Biomimetic Synthesis of Resveratrol Dimers and Systematic Evaluation of their Antioxidant Activities

An efficient synthetic route to the resveratrol oligomers quadrangularin A and pallidol is reported. It features a scalable biomimetic oxidative dimerization that proceeds in excellent yield and with complete regioselectivity. A systematic evaluation of the natural products and their synthetic precursors as radical‐trapping antioxidants has revealed that, contrary to popular belief, this mode of action is unlikely to account for their observed biological activity.Hartnäckigkeit zahlt sich aus: Eine kurze Synthese der Resveratrol‐Oligomere Quadrangularin A und Pallidol macht sich die Stabilität der von 2,6‐Di‐tert‐butylphenol abgeleiteten Radikal‐ und der Chinonmethid‐Zwischenstufe zunutze. Untersuchungen dieser Verbindungen als antioxidative Radikalfänger ergaben, dass diese Eigenschaft höchstwahrscheinlich nicht die Ursache ihrer beobachteten biologischen Aktivität ist
Porous Solids Arising from Synergistic and Competing Modes of Assembly: Combining Coordination Chemistry and Covalent Bond Formation

Design and synthesis of porous solids employing both reversible coordination chemistry and reversible covalent bond formation is described. The combination of two different linkage modes in a single material presents a link between two distinct classes of porous materials as exemplified by metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). This strategy, in addition to being a compelling material‐discovery method, also offers a platform for developing a fundamental understanding of the factors influencing the competing modes of assembly. We also demonstrate that even temporary formation of reversible connections between components may be leveraged to make new phases thus offering design routes to polymorphic frameworks. Moreover, this approach has the striking potential of providing a rich landscape of structurally complex materials from commercially available or readily accessible feedstocks.Auf gute Zusammenarbeit: Koordinationschemie und die Bildung kovalenter Bindungen können im selben Material zur gleichen Zeit auftreten. Ein Gleichgewicht zwischen Inkubationszeit der organischen Verbindungen und Solvenszerfall/Basenbildung steuert die Konkurrenz zwischen den beiden Prozessen und bestimmt die gebildete Phase. Selbst die temporäre Bildung reversibler Verknüpfungen zwischen Komponenten lässt sich zur Herstellung neuer Phasen nutzen
Total Synthesis of (−)-Caprazamycin A

Caprazamycin A has significant antibacterial activity against Mycobacterium tuberculosis (TB). The first total synthesis is herein reported and features a) the scalable preparation of the syn‐β‐hydroxy amino acid with a thiourea‐catalyzed diastereoselective aldol reaction, b) construction of a diazepanone with an unstable fatty‐acid side chain, and c) global deprotection with hydrogenation. This report provides a route for the synthesis of related liponucleoside antibiotics with fatty‐acid side chains
Ion‐Specific Oil Repellency of Polyelectrolyte Multilayers in Water: Molecular Insights into the Hydrophilicity of Charged Surfaces

Surface wetting on polyelectrolyte multilayers (PEMs), prepared by alternating deposition of polydiallyldimethylammonium chloride (PDDA) and poly(styrene sulfonate) (PSS), was investigated mainly in water‐solid‐oil systems. The surface‐wetting behavior of as‐prepared PEMs was well correlated to the molecular structures of the uncompensated ionic groups on the PEMs as revealed by sum frequency generation vibrational and X‐ray photoelectron spectroscopies. The orientation change of the benzenesulfonate groups on the PSS‐capped surfaces causes poor water wetting in oil or air and negligible oil wetting in water, while the orientation change of the quaternized pyrrolidine rings on the PDDA‐capped surfaces hardly affects their wetting behavior. The underwater oil repellency of PSS‐capped PEMs was successfully harnessed to manufacture highly efficient filters for oil‐water separation at high flux.Ölabweisend: Die Benetzbarkeit geladener Oberflächen korreliert mit der molekularen Natur der ionischen Gruppen. Bei isotroper Konfiguration haben Änderungen in der Orientierung der Gruppen kaum einen Einfluss auf die Wasserbenetzung. Bei anisotroper Konfiguration erfolgt ein Übergang von einer niedrigen Wasserbenetzung in Öl zu einer niedrigen Wasserentnetzung in Wasser, was zu exzellenten ölabweisenden Eigenschaften unter Wasser führt
Macrodiolide Formation by the Thioesterase of a Modular Polyketide Synthase

Elaiophylin is an unusual C2-symmetric antibiotic macrodiolide produced on a bacterial modular polyketide synthase assembly line. To probe the mechanism and selectivity of diolide formation, we sought to reconstitute ring formation in vitro by using a non-natural substrate. Incubation of recombinant elaiophylin thioesterase/cyclase with a synthetic pentaketide analogue of the presumed monomeric polyketide precursor of elaiophylin, specifically its N-acetylcysteamine thioester, produced a novel 16-membered C2-symmetric macrodiolide. A linear dimeric thioester is an intermediate in ring formation, which indicates iterative use of the thioesterase active site in ligation and subsequent cyclization. Furthermore, the elaiophylin thioesterase acts on a mixture of pentaketide and tetraketide thioesters to give both the symmetric decaketide diolide and the novel asymmetric hybrid nonaketide diolide. Such thioesterases have potential as tools for the in vitro construction of novel diolides.We gratefully acknowledge BBSRC (project grant BB/J007250/1 to P.F.L.), the European Commission (Marie Curie Fellowship to Y.Z.), and the University of Cambridge (Herchel Smith Research Fellowship to A.C.M.) and Dr. Katherine Stott (Department of Biochemistry, University of Cambridge) for help in AUC analysis. L.C.D. acknowledges the support of Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Proc. 2012/04616-3 and 2012/02230-0). P.F.L. is an International Research Awardee of the Alexander von Humboldt Foundation.This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/ange.201500401/full
A versatile room temperature route to di- and tri-substituted allenes via flow generated diazo compounds

This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/ange.201501538/abstract.A copper-catalysed coupling reaction between flow generated unstabilised diazo compounds and terminal alkynes providing di- and tri-substituted allenes is reported. This extremely mild and rapid transformation is highly tolerant of several functional groups.We are grateful to the Cambridge Home and European Scholarship Scheme (JSP), Swiss National Science Foundation (DNT), Pfizer Worldwide Research and Development (CB and JMH) and EPSRC (SVL, grant nº EP/K0099494/1 and nº EP/K039520/1) for financial support
Biosynthesis-Assisted Structural Elucidation of the Bartolosides, Chlorinated Aromatic Glycolipids from Cyanobacteria

The isolation of the bartolosides, unprecedented cyanobacterial glycolipids featuring aliphatic chains with chlorine substituents and C-glycosyl moieties, is reported. Their chlorinated dialkylresorcinol (DAR) core presented a major structural-elucidation challenge. To overcome this, we discovered the bartoloside (brt) biosynthetic gene cluster and linked it to the natural products through in vitro characterization of the DAR-forming ketosynthase and aromatase. Bioinformatic analysis also revealed a novel potential halogenase. Knowledge of the bartoloside biosynthesis constrained the DAR core structure by defining key pathway intermediates, ultimately allowing us to determine the full structures of the bartolosides. This work illustrates the power of genomics to enable the use of biosynthetic information for structure elucidation
An Autocatalytic System of Photooxidation-Driven Substitution Reactions on a Feᴵᴵ₄L₆ Cage Framework

This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/ange.201507045The functions of life are accomplished by systems exhibiting nonlinear kinetics: autocatalysis, in particular, is integral to the signal amplification that allows for biological information processing. Novel synthetic autocatalytic systems provide a foundation for the design of artificial chemical networks capable of carrying out complex functions. Here we report a few Feᴵᴵ₄L₆ cages containing BODIPY chromophores having tuneable photosensitizing properties. Electron-rich anilines were observed to displace electrondeficient anilines at the dynamic-covalent imine bonds of these cages. When iodoaniline residues were incorporated, heavy-atom effects led to enhanced ¹O₂ production. The incorporation of (methylthio)aniline residues into a cage allowed for the design of an autocatalytic system: oxidation of the methylthio groups into sulfoxides make them electron-deficient and allows their displacement by iodoanilines, generating a better photocatalyst and accelerating the reaction.This work was funded by the European Research Council (259352)
Three aromatic residues are required for electron transfer during iron mineralization in Bacterioferritin

Ferritins are iron storage proteins that overcome problems of toxicity and poor bioavailability of iron by catalysing iron oxidation and mineralization through the activity of a diiron ferroxidase site. Unlike in other ferritins, the oxidized di-Fe3+ site of Escherichia coli bacterioferritin (EcBFR) is stable and therefore does not function as a conduit for the transfer of Fe3+ into the storage cavity, but instead acts as a true catalytic cofactor that cycles its oxidation state while driving Fe2+ oxidation in the cavity. Here we demonstrate that EcBFR mineralization depends on three near-diiron site aromatic residues, Tyr25, Tyr58 and Trp133, and that a transient radical is formed on Tyr25. The data indicate that the aromatic residues, together with a previously identified inner surface iron site, promote mineralization by ensuring the simultaneous delivery of two electrons, derived from Fe2+ oxidation in the BFR cavity, to the di-ferric catalytic site for safe reduction of O2
[Ge2]4− Dumbbells with Very Short Ge−Ge Distances in the Zintl Phase Li3NaGe2: A Solid-State Equivalent to Molecular O2

This is the accepted manuscript. The final version is available at http://onlinelibrary.wiley.com/wol1/doi/10.1002/ange.201508044/abstract.The novel ternary Zintl phase Li3NaGe2 comprises alkali-metal cations and [Ge2]4− dumbbells. The diatomic [Ge2]4− unit is characterized by the shortest Ge−Ge distance (2.390(1) Å) ever observed in a Zintl phase and thus represents the first Ge=Ge double bond under such conditions, as also suggested by the (8−N) rule. Raman measurements support these findings. The multiple-bond character is confirmed by electronic-structure calculations, and an upfield 6Li NMR shift of −10.0 ppm, which was assigned to the Li cations surrounded by the π systems of three Ge dumbbells, further underlines this interpretation. For the unperturbed, ligand-free dumbbell in Li3NaGe2, the π- bonding py and pz orbitals are degenerate as in molecular oxygen, which has singly occupied orbitals. The partially filled π-type bands of the neat solid Li3NaGe2 cross the Fermi level, resulting in metallic properties. Li3NaGe2 was synthesized from the elements as well as from binary reactants and subsequently characterized crystallographically.O.P. acknowledges
support from a Marie Skłodowska-Curie Individual Fellowship.
L.M.S. is further grateful to the Fonds der Chemischen Industrie
and the Studienstiftung des deutschen Volkes for her fellowships.
A.J.K. gratefully acknowledges funding from the Alfred Kordelin
Foundation and computational resources from CSC – the Finnish
IT Center for Science
Influence of Equatorial CH⋅⋅⋅O Interactions on Secondary Kinetic Isotope Effects for Methyl Transfer

This is an Open Access articleDFT calculations for methyl cation complexed within a constrained cage of water molecules permit the controlled manipulation of the “axial” donor/acceptor distance and the “equatorial” distance to hydrogen-bond acceptors. The kinetic isotope effect k(CH3)/k(CT3) for methyl transfer within a cage with a short axial distance becomes less inverse for shorter equatorial C⋅⋅⋅O distances: a decrease of 0.5 Å results in a 3 % increase at 298 K. Kinetic isotope effects in AdoMet-dependent methyltransferases may be m∧odulated by CH⋅⋅⋅O hydrogen bonding, and factors other than axial compression may contribute, at least partially, to recently reported isotope-effect variations for catechol-O-methyltransferase and its mutant structures
Enantioselective synthesis of cyclobutylboronates via a copper-catalyzed desymmetrization approach

This is the peer reviewed version of the following article: Guisán-Ceinos, M., Parra, A., Martín-Heras, V. and Tortosa, M. (2016), Enantioselective Synthesis of Cyclobutylboronates via a Copper-Catalyzed Desymmetrization Approach. Angew. Chem., which has been published in final form at http://dx.doi.org/10.1002/ange.201601976. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.In this report, the first catalytic enantioselective synthesis
of cyclobutylboronates, using a chiral copper(I) complex, is disclosed.
A broad variety of cyclobutanes have been prepared with
consistently high levels of diastereo- and enantiocontrol. Moreover,
this method constitutes the first report of an enantioselective
desymmetrization of meso-cyclobutenes to prepare chiral
cyclobutanesWe thank the European Research Council (ERC-337776) and MINECO (CTQ2012-35957) for financial support. M. T. and A. P. thank MICINN for RyC and JdC contract
Few-layer antimonene by liquid-phase exfoliation

We report on a fast and simple method to produce highly stable isopropanol/water (4:1) suspensions of few-layer antimonene by liquid-phase exfoliation of antimony crystals in a process that is assisted by sonication but does not require the addition of any surfactant. This straightforward method generates dispersions of few-layer antimonene suitable for on-surface isolation. Analysis by atomic force microscopy, scanning transmission electron microscopy, and electron energy loss spectroscopy confirmed the formation of high-quality few-layer antimonene nanosheets with large lateral dimensions. These nanolayers are extremely stable under ambient conditions. Their Raman signals are strongly thickness-dependent, which was rationalized by means of density functional theory calculations.EC/FP7/604391/EU/Graphene-Based Revolutions in ICT And Beyond/GRAPHENEEC/FP7/259286/EU/Characterizing and Controlling Carbon Nanomaterials/CCCANDFG, SPP 1459, GrapheneEC/FP7/627386/EU/Multifunctional Graphene by means of a Chemical Approach/MULTIGRAPHCHE
Direct and Stereospecific Synthesis of N-H and N-Alkyl Aziridines from Unactivated Olefins Using Hydroxylamine-O-Sulfonic Acids

A RhII-catalyzed direct and stereospecific N-H- and N-alkyl aziridination of olefins is reported that uses hydroxylamine-O-sulfonic acids as inexpensive, readily available, and nitro group-free aminating reagents. Unactivated olefins, featuring a wide range of functional groups, are converted into the corresponding N-H or N-alkyl aziridines in good to excellent yields. This operationally simple, scalable transformation proceeds efficiently at ambient temperature and is tolerant towards oxygen and trace moisture