Strategies for microbial synthesis of high-value phytochemicals Nat. Chem. (IF 25.87) Pub Date : 2018-03-22 Sijin Li, Yanran Li, Christina D. Smolke
Phytochemicals are of great pharmaceutical and agricultural importance, but often exhibit low abundance in nature. Recent demonstrations of industrial-scale production of phytochemicals in yeast have shown that microbial production of these high-value chemicals is a promising alternative to sourcing these molecules from native plant hosts. However, a number of challenges remain in the broader application of this approach, including the limited knowledge of plant secondary metabolism and the inefficient reconstitution of plant metabolic pathways in microbial hosts. In this Review, we discuss recent strategies to achieve microbial biosynthesis of complex phytochemicals, including strategies to: (1) reconstruct plant biosynthetic pathways that have not been fully elucidated by mining enzymes from native and non-native hosts or by enzyme engineering; (2) enhance plant enzyme activity, specifically cytochrome P450 activity, by improving efficiency, selectivity, expression or electron transfer; and (3) enhance overall reaction efficiency of multi-enzyme pathways by dynamic control, compartmentalization or optimization with the host’s metabolism. We also highlight remaining challenges to — and future opportunities of — this approach.
Foldamers wave to the ribosome Nat. Chem. (IF 25.87) Pub Date : 2018-03-22 Alanna Schepartz
Foldamers wave to the ribosome Foldamers wave to the ribosome, Published online: 22 March 2018; doi:10.1038/s41557-018-0036-5 Ribosomes have now been shown to accept certain initiator tRNAs acylated with aromatic foldamer–dipeptides thereby enabling the translation of a peptide or protein with a short aromatic foldamer at the N-terminus. Some foldamer–peptide hybrids could be cyclized to generate macrocycles that present conformationally restricted peptide loops.
Made in translation Nat. Chem. (IF 25.87) Pub Date : 2018-03-22 John C. Chaput
Made in translation Made in translation, Published online: 22 March 2018; doi:10.1038/s41557-018-0034-7 Evolution of highly functionalized DNA could enable the discovery of artificial nucleic acid sequences with different properties to natural DNA. Now, an artificial translation system has been designed that can support the evolution of non-natural sequence-defined nucleic acid polymers carrying eight different functional groups on 32 codons.
Organic synthesis provides opportunities to transform drug discovery Nat. Chem. (IF 25.87) Pub Date : 2018-03-22 David C. Blakemore, Luis Castro, Ian Churcher, David C. Rees, Andrew W. Thomas, David M. Wilson, Anthony Wood
Despite decades of ground-breaking research in academia, organic synthesis is still a rate-limiting factor in drug-discovery projects. Here we present some current challenges in synthetic organic chemistry from the perspective of the pharmaceutical industry and highlight problematic steps that, if overcome, would find extensive application in the discovery of transformational medicines. Significant synthesis challenges arise from the fact that drug molecules typically contain amines and N-heterocycles, as well as unprotected polar groups. There is also a need for new reactions that enable non-traditional disconnections, more C–H bond activation and late-stage functionalization, as well as stereoselectively substituted aliphatic heterocyclic ring synthesis, C–X or C–C bond formation. We also emphasize that syntheses compatible with biomacromolecules will find increasing use, while new technologies such as machine-assisted approaches and artificial intelligence for synthesis planning have the potential to dramatically accelerate the drug-discovery process. We believe that increasing collaboration between academic and industrial chemists is crucial to address the challenges outlined here.
Hidden hassium Nat. Chem. (IF 25.87) Pub Date : 2018-03-22 Michael A. Tarselli
Hidden hassium Hidden hassium, Published online: 22 March 2018; doi:10.1038/s41557-018-0037-4 From its scarcity to political intrigue over naming conventions, element 108’s story describes how international cooperation overcame the limits of nuclear science, says Michael Tarselli.
Experimental and computational evidence of halogen bonds involving astatine Nat. Chem. (IF 25.87) Pub Date : 2018-03-19 Ning Guo, Rémi Maurice, David Teze, Jérôme Graton, Julie Champion, Gilles Montavon, Nicolas Galland
The importance of halogen bonds—highly directional interactions between an electron-deficient σ-hole moiety in a halogenated compound and an acceptor such as a Lewis base—is being increasingly recognized in a wide variety of fields from biomedicinal chemistry to materials science. The heaviest halogens are known to form stronger halogen bonds, implying that if this trend continues down the periodic table, astatine should exhibit the highest halogen-bond donating ability. This may be mitigated, however, by the relativistic effects undergone by heavy elements, as illustrated by the metallic character of astatine. Here, the occurrence of halogen-bonding interactions involving astatine is experimentally evidenced. The complexation constants of astatine monoiodide with a series of organic ligands in cyclohexane solution were derived from distribution coefficient measurements and supported by relativistic quantum mechanical calculations. Taken together, the results show that astatine indeed behaves as a halogen-bond donor—a stronger one than iodine—owing to its much more electrophilic σ-hole.
Versatile protein recognition by the encoded display of multiple chemical elements on a constant macrocyclic scaffold Nat. Chem. (IF 25.87) Pub Date : 2018-03-19 Yizhou Li, Roberto De Luca, Samuele Cazzamalli, Francesca Pretto, Davor Bajic, Jörg Scheuermann, Dario Neri
In nature, specific antibodies can be generated as a result of an adaptive selection and expansion of lymphocytes with suitable protein binding properties. We attempted to mimic antibody–antigen recognition by displaying multiple chemical diversity elements on a defined macrocyclic scaffold. Encoding of the displayed combinations was achieved using distinctive DNA tags, resulting in a library size of 35,393,112. Specific binders could be isolated against a variety of proteins, including carbonic anhydrase IX, horseradish peroxidase, tankyrase 1, human serum albumin, alpha-1 acid glycoprotein, calmodulin, prostate-specific antigen and tumour necrosis factor. Similar to antibodies, the encoded display of multiple chemical elements on a constant scaffold enabled practical applications, such as fluorescence microscopy procedures or the selective in vivo delivery of payloads to tumours. Furthermore, the versatile structure of the scaffold facilitated the generation of protein-specific chemical probes, as illustrated by photo-crosslinking.
Ribosomal synthesis and folding of peptide-helical aromatic foldamer hybrids Nat. Chem. (IF 25.87) Pub Date : 2018-03-19 Joseph M. Rogers, Sunbum Kwon, Simon J. Dawson, Pradeep K. Mandal, Hiroaki Suga, Ivan Huc
Translation, the mRNA-templated synthesis of peptides by the ribosome, can be manipulated to incorporate variants of the 20 cognate amino acids. Such approaches for expanding the range of chemical entities that can be produced by the ribosome may accelerate the discovery of molecules that can perform functions for which poorly folded, short peptidic sequences are ill suited. Here, we show that the ribosome tolerates some artificial helical aromatic oligomers, so-called foldamers. Using a flexible tRNA-acylation ribozyme—flexizyme—foldamers were attached to tRNA, and the resulting acylated tRNAs were delivered to the ribosome to initiate the synthesis of non-cyclic and cyclic foldamer–peptide hybrid molecules. Passing through the ribosome exit tunnel requires the foldamers to unfold. Yet foldamers encode sufficient folding information to influence the peptide structure once translation is completed. We also show that in cyclic hybrids, the foldamer portion can fold into a helix and force the peptide segment to adopt a constrained and stretched conformation.
Evidence for a vibrational phase-dependent isotope effect on the photochemistry of vision Nat. Chem. (IF 25.87) Pub Date : 2018-03-19 C. Schnedermann, X. Yang, M. Liebel, K. M. Spillane, J. Lugtenburg, I. Fernández, A. Valentini, I. Schapiro, M. Olivucci, P. Kukura, R. A. Mathies
Vibronic coupling is key to efficient energy flow in molecular systems and a critical component of most mechanisms invoking quantum effects in biological processes. Despite increasing evidence for coherent coupling of electronic states being mediated by vibrational motion, it is not clear how and to what degree properties associated with vibrational coherence such as phase and coupling of atomic motion can impact the efficiency of light-induced processes under natural, incoherent illumination. Here, we show that deuteration of the H11–C11=C12–H12 double-bond of the 11-cis retinal chromophore in the visual pigment rhodopsin significantly and unexpectedly alters the photoisomerization yield while inducing smaller changes in the ultrafast isomerization dynamics assignable to known isotope effects. Combination of these results with non-adiabatic molecular dynamics simulations reveals a vibrational phase-dependent isotope effect that we suggest is an intrinsic attribute of vibronically coherent photochemical processes.
Genetically encoded lipid–polypeptide hybrid biomaterials that exhibit temperature-triggered hierarchical self-assembly Nat. Chem. (IF 25.87) Pub Date : 2018-03-19 Davoud Mozhdehi, Kelli M. Luginbuhl, Joseph R. Simon, Michael Dzuricky, Rüdiger Berger, H. Samet Varol, Fred C. Huang, Kristen L. Buehne, Nicholas R. Mayne, Isaac Weitzhandler, Mischa Bonn, Sapun H. Parekh, Ashutosh Chilkoti
Post-translational modification of proteins is a strategy widely used in biological systems. It expands the diversity of the proteome and allows for tailoring of both the function and localization of proteins within cells as well as the material properties of structural proteins and matrices. Despite their ubiquity in biology, with a few exceptions, the potential of post-translational modifications in biomaterials synthesis has remained largely untapped. As a proof of concept to demonstrate the feasibility of creating a genetically encoded biohybrid material through post-translational modification, we report here the generation of a family of three stimulus-responsive hybrid materials—fatty-acid-modified elastin-like polypeptides—using a one-pot recombinant expression and post-translational lipidation methodology. These hybrid biomaterials contain an amphiphilic domain, composed of a β-sheet-forming peptide that is post-translationally functionalized with a C14 alkyl chain, fused to a thermally responsive elastin-like polypeptide. They exhibit temperature-triggered hierarchical self-assembly across multiple length scales with varied structure and material properties that can be controlled at the sequence level.
Dynamic protein assembly by programmable DNA strand displacement Nat. Chem. (IF 25.87) Pub Date : 2018-03-12 Rebecca P. Chen, Daniel Blackstock, Qing Sun, Wilfred Chen
Abstract Inspired by the remarkable ability of natural protein switches to sense and respond to a wide range of environmental queues, here we report a strategy to engineer synthetic protein switches by using DNA strand displacement to dynamically organize proteins with highly diverse and complex logic gate architectures. We show that DNA strand displacement can be used to dynamically control the spatial proximity and the corresponding fluorescence resonance energy transfer between two fluorescent proteins. Performing Boolean logic operations enabled the explicit control of protein proximity using multi-input, reversible and amplification architectures. We further demonstrate the power of this technology beyond sensing by achieving dynamic control of an enzyme cascade. Finally, we establish the utility of the approach as a synthetic computing platform that drives the dynamic reconstitution of a split enzyme for targeted prodrug activation based on the sensing of cancer-specific miRNAs.
Sticky when wet Nat. Chem. (IF 25.87) Pub Date : 2018-03-12 Ji Chen, Angelos Michaelides
Sticky when wet Sticky when wet, Published online: 12 March 2018; doi:10.1038/s41557-018-0024-9 The aqueous hydronium cation diffuses about twice as fast as the aqueous hydroxide anion in liquid water, but the origin of this behaviour has been unclear. Now, state-of-the-art simulations provide an explanation for this long-standing conundrum.
Crystal phase-based epitaxial growth of hybrid noble metal nanostructures on 4H/fcc Au nanowires Nat. Chem. (IF 25.87) Pub Date : 2018-03-12 Qipeng Lu, An-Liang Wang, Yue Gong, Wei Hao, Hongfei Cheng, Junze Chen, Bing Li, Nailiang Yang, Wenxin Niu, Jie Wang, Yifu Yu, Xiao Zhang, Ye Chen, Zhanxi Fan, Xue-Jun Wu, Jinping Chen, Jun Luo, Shuzhou Li, Lin Gu, Hua Zhang
Crystal-phase engineering offers opportunities for the rational design and synthesis of noble metal nanomaterials with unusual crystal phases that normally do not exist in bulk materials. However, it remains a challenge to use these materials as seeds to construct heterometallic nanostructures with desired crystal phases and morphologies for promising applications such as catalysis. Here, we report a strategy for the synthesis of binary and ternary hybrid noble metal nanostructures. Our synthesized crystal-phase heterostructured 4H/fcc Au nanowires enable the epitaxial growth of Ru nanorods on the 4H phase and fcc-twin boundary in Au nanowires, resulting in hybrid Au–Ru nanowires. Moreover, the method can be extended to the epitaxial growth of Rh, Ru–Rh and Ru–Pt nanorods on the 4H/fcc Au nanowires to form unique hybrid nanowires. Importantly, the Au–Ru hybrid nanowires with tunable compositions exhibit excellent electrocatalytic performance towards the hydrogen evolution reaction in alkaline media.
Hydroxide diffuses slower than hydronium in water because its solvated structure inhibits correlated proton transfer Nat. Chem. (IF 25.87) Pub Date : 2018-03-12 Mohan Chen, Lixin Zheng, Biswajit Santra, Hsin-Yu Ko, Robert A. DiStasio Jr, Michael L. Klein, Roberto Car, Xifan Wu
Proton transfer via hydronium and hydroxide ions in water is ubiquitous. It underlies acid–base chemistry, certain enzyme reactions, and even infection by the flu. Despite two centuries of investigation, the mechanism underlying why hydroxide diffuses slower than hydronium in water is still not well understood. Herein, we employ state-of-the-art density-functional-theory-based molecular dynamics—with corrections for non-local van der Waals interactions, and self-interaction in the electronic ground state—to model water and hydrated water ions. At this level of theory, we show that structural diffusion of hydronium preserves the previously recognized concerted behaviour. However, by contrast, proton transfer via hydroxide is less temporally correlated, due to a stabilized hypercoordination solvation structure that discourages proton transfer. Specifically, the latter exhibits non-planar geometry, which agrees with neutron-scattering results. Asymmetry in the temporal correlation of proton transfer leads to hydroxide diffusing slower than hydronium.
Evolution of sequence-defined highly functionalized nucleic acid polymers Nat. Chem. (IF 25.87) Pub Date : 2018-03-05 Zhen Chen, Phillip A. Lichtor, Adrian P. Berliner, Jonathan C. Chen, David R. Liu
The evolution of sequence-defined synthetic polymers made of building blocks beyond those compatible with polymerase enzymes or the ribosome has the potential to generate new classes of receptors, catalysts and materials. Here we describe a ligase-mediated DNA-templated polymerization and in vitro selection system to evolve highly functionalized nucleic acid polymers (HFNAPs) made from 32 building blocks that contain eight chemically diverse side chains on a DNA backbone. Through iterated cycles of polymer translation, selection and reverse translation, we discovered HFNAPs that bind proprotein convertase subtilisin/kexin type 9 (PCSK9) and interleukin-6, two protein targets implicated in human diseases. Mutation and reselection of an active PCSK9-binding polymer yielded evolved polymers with high affinity (KD = 3 nM). This evolved polymer potently inhibited the binding between PCSK9 and the low-density lipoprotein receptor. Structure–activity relationship studies revealed that specific side chains at defined positions in the polymers are required for binding to their respective targets. Our findings expand the chemical space of evolvable polymers to include densely functionalized nucleic acids with diverse, researcher-defined chemical repertoires.
Control over phase separation and nucleation using a laser-tweezing potential Nat. Chem. (IF 25.87) Pub Date : 2018-03-05 Finlay Walton, Klaas Wynne
Control over the nucleation of new phases is highly desirable but elusive. Even though there is a long history of crystallization engineering by varying physicochemical parameters, controlling which polymorph crystallizes or whether a molecule crystallizes or forms an amorphous precipitate is still a poorly understood practice. Although there are now numerous examples of control using laser-induced nucleation, the absence of physical understanding is preventing progress. Here we show that the proximity of a liquid–liquid critical point or the corresponding binodal line can be used by a laser-tweezing potential to induce concentration gradients. A simple theoretical model shows that the stored electromagnetic energy of the laser beam produces a free-energy potential that forces phase separation or triggers the nucleation of a new phase. Experiments in a liquid mixture using a low-power laser diode confirm the effect. Phase separation and nucleation using a laser-tweezing potential explains the physics behind non-photochemical laser-induced nucleation and suggests new ways of manipulating matter.
Chemical evolution of atmospheric organic carbon over multiple generations of oxidation Nat. Chem. (IF 25.87) Pub Date : 2018-02-26 Gabriel Isaacman-VanWertz, Paola Massoli, Rachel O’Brien, Christopher Lim, Jonathan P. Franklin, Joshua A. Moss, James F. Hunter, John B. Nowak, Manjula R. Canagaratna, Pawel K. Misztal, Caleb Arata, Joseph R. Roscioli, Scott T. Herndon, Timothy B. Onasch, Andrew T. Lambe, John T. Jayne, Luping Su, Daniel A. Knopf, Allen H. Goldstein, Douglas R. Worsnop, Jesse H. Kroll
The evolution of atmospheric organic carbon as it undergoes oxidation has a controlling influence on concentrations of key atmospheric species, including particulate matter, ozone and oxidants. However, full characterization of organic carbon over hours to days of atmospheric processing has been stymied by its extreme chemical complexity. Here we study the multigenerational oxidation of α-pinene in the laboratory, characterizing products with several state-of-the-art analytical techniques. Although quantification of some early generation products remains elusive, full carbon closure is achieved (within measurement uncertainty) by the end of the experiments. These results provide new insights into the effects of oxidation on organic carbon properties (volatility, oxidation state and reactivity) and the atmospheric lifecycle of organic carbon. Following an initial period characterized by functionalization reactions and particle growth, fragmentation reactions dominate, forming smaller species. After approximately one day of atmospheric aging, most carbon is sequestered in two long-lived reservoirs—volatile oxidized gases and low-volatility particulate matter.
Observation of the adsorption and desorption of vibrationally excited molecules on a metal surface Nat. Chem. (IF 25.87) Pub Date : 2018-02-26 Pranav R. Shirhatti, Igor Rahinov, Kai Golibrzuch, Jörn Werdecker, Jan Geweke, Jan Altschäffel, Sumit Kumar, Daniel J. Auerbach, Christof Bartels, Alec M. Wodtke
The most common mechanism of catalytic surface chemistry is that of Langmuir and Hinshelwood (LH). In the LH mechanism, reactants adsorb, become thermalized with the surface, and subsequently react. The measured vibrational (relaxation) lifetimes of molecules adsorbed at metal surfaces are in the range of a few picoseconds. As a consequence, vibrational promotion of LH chemistry is rarely observed, with the exception of LH reactions occurring via a molecular physisorbed intermediate. Here, we directly detect adsorption and subsequent desorption of vibrationally excited CO molecules from a Au(111) surface. Our results show that CO (v = 1) survives on a Au(111) surface for ~1 × 10−10 s. Such long vibrational lifetimes for adsorbates on metal surfaces are unexpected and pose an interesting challenge to the current understanding of vibrational energy dissipation on metal surfaces. They also suggest that vibrational promotion of surface chemistry might be more common than is generally believed.
Uranium electrocatalysis: The secret is in the ring Nat. Chem. (IF 25.87) Pub Date : 2018-02-20 Marinella Mazzanti
Uranium electrocatalysis: The secret is in the ring Uranium electrocatalysis: The secret is in the ring, Published online: 20 February 2018; doi:10.1038/nchem.2940 An arene-anchored uranium complex has recently been shown to serve as efficient electrocatalyst for the conversion of water into dihydrogen. Now, the crucial role of the arene moiety in enabling catalytic activity — unusual for uranium — has been explored, providing important insight for the design of improved electrocatalysts.
Biosynthesis: Reprogramming assembly lines Nat. Chem. (IF 25.87) Pub Date : 2018-02-20 Binuraj R. K. Menon, Matthew Jenner
Biosynthesis: Reprogramming assembly lines Biosynthesis: Reprogramming assembly lines, Published online: 20 February 2018; doi:10.1038/nchem.2941 Rational engineering of biosynthetic assembly lines for production of new compounds is an attractive prospect, yet it presents many challenges. Learning from biology, some of the rules for expanding the chemical diversity of non-ribosomal peptides have been uncovered in two recent studies.
Scattering resonances in bimolecular collisions between NO radicals and H2 challenge the theoretical gold standard Nat. Chem. (IF 25.87) Pub Date : 2018-02-19 Sjoerd N. Vogels, Tijs Karman, Jacek Kłos, Matthieu Besemer, Jolijn Onvlee, Ad van der Avoird, Gerrit C. Groenenboom, Sebastiaan Y. T. van de Meerakker
Over the last 25 years, the formalism known as coupled-cluster (CC) theory has emerged as the method of choice for the ab initio calculation of intermolecular interaction potentials. The implementation known as CCSD(T) is often referred to as the gold standard in quantum chemistry. It gives excellent agreement with experimental observations for a variety of energy-transfer processes in molecular collisions, and it is used to calibrate density functional theory. Here, we present measurements of low-energy collisions between NO radicals and H2 molecules with a resolution that challenges the most sophisticated quantum chemistry calculations at the CCSD(T) level. Using hitherto-unexplored anti-seeding techniques to reduce the collision energy in a crossed-beam inelastic-scattering experiment, a resonance structure near 14 cm−1 is clearly resolved in the state-to-state integral cross-section, and a unique resonance fingerprint is observed in the corresponding differential cross-section. This resonance structure discriminates between two NO–H2 potentials calculated at the CCSD(T) level and pushes the required accuracy beyond the gold standard.
Observation of correlated excitations in bimolecular collisions Nat. Chem. (IF 25.87) Pub Date : 2018-02-19 Zhi Gao, Tijs Karman, Sjoerd N. Vogels, Matthieu Besemer, Ad van der Avoird, Gerrit C. Groenenboom, Sebastiaan Y. T. van de Meerakker
Although collisions between atoms and molecules are largely understood, collisions between two molecules have proven much harder to study. In both experiment and theory, our ability to determine quantum-state-resolved bimolecular cross-sections lags behind their atom–molecule counterparts by decades. For many bimolecular systems, even rules of thumb—much less intuitive understanding—of scattering cross sections are lacking. Here, we report the measurement of state-to-state differential cross sections on the collision of state-selected and velocity-controlled nitric oxide (NO) radicals and oxygen (O2) molecules. Using velocity map imaging of the scattered NO radicals, the full product-pair correlations of rotational excitation that occurs in both collision partners from individual encounters are revealed. The correlated cross sections show surprisingly good agreement with quantum scattering calculations using ab initio NO−O2 potential energy surfaces. The observations show that the well-known energy-gap law that governs atom–molecule collisions does not generally apply to bimolecular excitation processes, and reveal a propensity rule for the vector correlation of product angular momenta.
Corrigendum: Structural snapshots of concerted double E–H bond activation at a transition metal centre Nat. Chem. (IF 25.87) Pub Date : 2018-01-23 Joseph A. B. Abdalla, Alexa Caise, Christian P. Sindlinger, Rémi Tirfoin, Amber L. Thompson, Alison J. Edwards, Simon Aldridge
Corrigendum: Structural snapshots of concerted double E–H bond activation at a transition metal centre Corrigendum: Structural snapshots of concerted double E–H bond activation at a transition metal centre, Published online: 23 January 2018; doi:10.1038/nchem.2922 Corrigendum: Structural snapshots of concerted double E–H bond activation at a transition metal centre
Erratum: Activate lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution Nat. Chem. (IF 25.87) Pub Date : 2018-01-23 Alexis Grimaud, Oscar Diaz-Morales, Binghong Han, Wesley T. Hong, Yueh-Lin Lee, Livia Giordano, Kelsey A. Stoerzinger, Marc T. M. Koper, Yang Shao-Horn
Erratum: Activate lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution Erratum: Activate lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution, Published online: 23 January 2018; doi:10.1038/nchem.2932 Erratum: Activate lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution
C–H carbonylation: In situ acyl triflates ace it Nat. Chem. (IF 25.87) Pub Date : 2018-01-23 Yong Ho Lee, Bill Morandi
C–H carbonylation: In situ acyl triflates ace it C–H carbonylation: In situ acyl triflates ace it, Published online: 23 January 2018; doi:10.1038/nchem.2934 A simple palladium catalyst has mediated the facile formation of aroyl triflates — an extremely reactive class of electrophiles. These intermediates, generated in situ, enable the Friedel–Crafts acylation of traditionally unreactive arenes, addressing a significant gap in C–H carbonylation methodology.
Mass spectrometry: Raw protein from the top down Nat. Chem. (IF 25.87) Pub Date : 2018-01-23 Kathrin Breuker
Mass spectrometry: Raw protein from the top down Mass spectrometry: Raw protein from the top down, Published online: 23 January 2018; doi:10.1038/nchem.2936 Mass spectrometry is a powerful technique for analysing proteins, yet linking higher-order protein structure to amino acid sequence and post-translational modifications is far from simple. Now, a native top-down method has been developed that can provide information on higher-order protein structure and different proteoforms at the same time.
The germination of germanium Nat. Chem. (IF 25.87) Pub Date : 2018-01-23 Shawn C. Burdette, Brett F. Thornton
The germination of germanium The germination of germanium, Published online: 23 January 2018; doi:10.1038/nchem.2935 Shawn C. Burdette and Brett F. Thornton explore how germanium developed from a missing element in Mendeleev's periodic table to an enabler for the information age, while retaining a nomenclature oddity.
Solution-phase reaction dynamics: Gaining control Nat. Chem. (IF 25.87) Pub Date : 2018-01-23 Amanda S. Case
Solution-phase reaction dynamics: Gaining control Solution-phase reaction dynamics: Gaining control, Published online: 23 January 2018; doi:10.1038/nchem.2937 Using infrared light to control the outcome of a chemical reaction is problematic in solution because of numerous interactions and non-specific sample heating. Now, condensed-phase results showing the vibrational enhancement of an otherwise thermally driven reaction may reinvigorate discussion of the practical applications of vibrational control.
Complex supramolecular interfacial tessellation through convergent multi-step reaction of a dissymmetric simple organic precursor Nat. Chem. (IF 25.87) Pub Date : 2018-01-22 Yi-Qi Zhang, Mateusz Paszkiewicz, Ping Du, Liding Zhang, Tao Lin, Zhi Chen, Svetlana Klyatskaya, Mario Ruben, Ari P. Seitsonen, Johannes V. Barth, Florian Klappenberger
Interfacial supramolecular self-assembly represents a powerful tool for constructing regular and quasicrystalline materials. In particular, complex two-dimensional molecular tessellations, such as semi-regular Archimedean tilings with regular polygons, promise unique properties related to their nontrivial structures. However, their formation is challenging, because current methods are largely limited to the direct assembly of precursors, that is, where structure formation relies on molecular interactions without using chemical transformations. Here, we have chosen ethynyl-iodophenanthrene (which features dissymmetry in both geometry and reactivity) as a single starting precursor to generate the rare semi-regular (22.214.171.124) Archimedean tiling with long-range order on an atomically flat substrate through a multi-step reaction. Intriguingly, the individual chemical transformations converge to form a symmetric alkynyl–Ag–alkynyl complex as the new tecton in high yields. Using a combination of microscopy and X-ray spectroscopy tools, as well as computational modelling, we show that in situ generated catalytic Ag complexes mediate the tecton conversion.
Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2 Nat. Chem. (IF 25.87) Pub Date : 2018-01-22 Urmimala Maitra, Robert A. House, James W. Somerville, Nuria Tapia-Ruiz, Juan G. Lozano, Niccoló Guerrini, Rong Hao, Kun Luo, Liyu Jin, Miguel A. Pérez-Osorio, Felix Massel, David M. Pickup, Silvia Ramos, Xingye Lu, Daniel E. McNally, Alan V. Chadwick, Feliciano Giustino, Thorsten Schmitt, Laurent C. Duda, Matthew R. Roberts, Peter G. Bruce
The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li+–O(2p)–Li+ interactions). Na2/3[Mg0.28Mn0.72]O2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg2+ resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na2/3[Mg0.28Mn0.72]O2 does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg2+ remains in Na2/3[Mg0.28Mn0.72]O2, which stabilizes oxygen.
Evolving artificial metalloenzymes via random mutagenesis Nat. Chem. (IF 25.87) Pub Date : 2018-01-22 Hao Yang, Alan M. Swartz, Hyun June Park, Poonam Srivastava, Ken Ellis-Guardiola, David M. Upp, Gihoon Lee, Ketaki Belsare, Yifan Gu, Chen Zhang, Raymond E. Moellering, Jared C. Lewis
Random mutagenesis has the potential to optimize the efficiency and selectivity of protein catalysts without requiring detailed knowledge of protein structure; however, introducing synthetic metal cofactors complicates the expression and screening of enzyme libraries, and activity arising from free cofactor must be eliminated. Here we report an efficient platform to create and screen libraries of artificial metalloenzymes (ArMs) via random mutagenesis, which we use to evolve highly selective dirhodium cyclopropanases. Error-prone PCR and combinatorial codon mutagenesis enabled multiplexed analysis of random mutations, including at sites distal to the putative ArM active site that are difficult to identify using targeted mutagenesis approaches. Variants that exhibited significantly improved selectivity for each of the cyclopropane product enantiomers were identified, and higher activity than previously reported ArM cyclopropanases obtained via targeted mutagenesis was also observed. This improved selectivity carried over to other dirhodium-catalysed transformations, including N–H, S–H and Si–H insertion, demonstrating that ArMs evolved for one reaction can serve as starting points to evolve catalysts for others.
Coherent wavepackets in the Fenna–Matthews–Olson complex are robust to excitonic-structure perturbations caused by mutagenesis Nat. Chem. (IF 25.87) Pub Date : 2018-01-15 Margherita Maiuri, Evgeny E. Ostroumov, Rafael G. Saer, Robert E. Blankenship, Gregory D. Scholes
Femtosecond pulsed excitation of light-harvesting complexes creates oscillatory features in their response. This phenomenon has inspired a large body of work aimed at uncovering the origin of the coherent beatings and possible implications for function. Here we exploit site-directed mutagenesis to change the excitonic level structure in Fenna–Matthews–Olson (FMO) complexes and compare the coherences using broadband pump–probe spectroscopy. Our experiments detect two oscillation frequencies with dephasing on a picosecond timescale—both at 77 K and at room temperature. By studying these coherences with selective excitation pump–probe experiments, where pump excitation is in resonance only with the lowest excitonic state, we show that the key contributions to these oscillations stem from ground-state vibrational wavepackets. These experiments explicitly show that the coherences—although in the ground electronic state—can be probed at the absorption resonances of other bacteriochlorophyll molecules because of delocalization of the electronic excitation over several chromophores.
Transferring the entatic-state principle to copper photochemistry Nat. Chem. (IF 25.87) Pub Date : 2018-01-15 B. Dicke, A. Hoffmann, J. Stanek, M. S. Rampp, B. Grimm-Lebsanft, F. Biebl, D. Rukser, B. Maerz, D. Göries, M. Naumova, M. Biednov, G. Neuber, A. Wetzel, S. M. Hofmann, P. Roedig, A. Meents, J. Bielecki, J. Andreasson, K. R. Beyerlein, H. N. Chapman, C. Bressler, W. Zinth, M. Rübhausen, S. Herres-Pawlis
The entatic state denotes a distorted coordination geometry of a complex from its typical arrangement that generates an improvement to its function. The entatic-state principle has been observed to apply to copper electron-transfer proteins and it results in a lowering of the reorganization energy of the electron-transfer process. It is thus crucial for a multitude of biochemical processes, but its importance to photoactive complexes is unexplored. Here we study a copper complex—with a specifically designed constraining ligand geometry—that exhibits metal-to-ligand charge-transfer state lifetimes that are very short. The guanidine–quinoline ligand used here acts on the bis(chelated) copper(I) centre, allowing only small structural changes after photoexcitation that result in very fast structural dynamics. The data were collected using a multimethod approach that featured time-resolved ultraviolet–visible, infrared and X-ray absorption and optical emission spectroscopy. Through supporting density functional calculations, we deliver a detailed picture of the structural dynamics in the picosecond-to-nanosecond time range.
Evaluating differences in the active-site electronics of supported Au nanoparticle catalysts using Hammett and DFT studies Nat. Chem. (IF 25.87) Pub Date : 2018-01-15 Gaurav Kumar, Luke Tibbitts, Jaclyn Newell, Basu Panthi, Ahana Mukhopadhyay, Robert M. Rioux, Christopher J. Pursell, Michael Janik, Bert D. Chandler
Supported metal catalysts, which are composed of metal nanoparticles dispersed on metal oxides or other high-surface-area materials, are ubiquitous in industrially catalysed reactions. Identifying and characterizing the catalytic active sites on these materials still remains a substantial challenge, even though it is required to guide rational design of practical heterogeneous catalysts. Metal–support interactions have an enormous impact on the chemistry of the catalytic active site and can determine the optimum support for a reaction; however, few direct probes of these interactions are available. Here we show how benzyl alcohol oxidation Hammett studies can be used to characterize differences in the catalytic activity of Au nanoparticles hosted on various metal-oxide supports. We combine reactivity analysis with density functional theory calculations to demonstrate that the slope of experimental Hammett plots is affected by electron donation from the underlying oxide support to the Au particles.
Engineered modular biomaterial logic gates for environmentally triggered therapeutic delivery Nat. Chem. (IF 25.87) Pub Date : 2018-01-15 Barry A. Badeau, Michael P. Comerford, Christopher K. Arakawa, Jared A. Shadish, Cole A. DeForest
The successful transport of drug- and cell-based therapeutics to diseased sites represents a major barrier in the development of clinical therapies. Targeted delivery can be mediated through degradable biomaterial vehicles that utilize disease biomarkers to trigger payload release. Here, we report a modular chemical framework for imparting hydrogels with precise degradative responsiveness by using multiple environmental cues to trigger reactions that operate user-programmable Boolean logic. By specifying the molecular architecture and connectivity of orthogonal stimuli-labile moieties within material cross-linkers, we show selective control over gel dissolution and therapeutic delivery. To illustrate the versatility of this methodology, we synthesized 17 distinct stimuli-responsive materials that collectively yielded all possible YES/OR/AND logic outputs from input combinations involving enzyme, reductant and light. Using these hydrogels we demonstrate the first sequential and environmentally stimulated release of multiple cell lines in well-defined combinations from a material. We expect these platforms will find utility in several diverse fields including drug delivery, diagnostics and regenerative medicine.
Ultrafast dynamics of low-energy electron attachment via a non-valence correlation-bound state Nat. Chem. (IF 25.87) Pub Date : 2018-01-08 Joshua P. Rogers, Cate S. Anstöter, Jan R. R. Verlet
The primary electron-attachment process in electron-driven chemistry represents one of the most fundamental chemical transformations with wide-ranging importance in science and technology. However, the mechanistic detail of the seemingly simple reaction of an electron and a neutral molecule to form an anion remains poorly understood, particularly at very low electron energies. Here, time-resolved photoelectron imaging was used to probe the electron-attachment process to a non-polar molecule using time-resolved methods. An initially populated diffuse non-valence state of the anion that is bound by correlation forces evolves coherently in ∼30 fs into a valence state of the anion. The extreme efficiency with which the correlation-bound state serves as a doorway state for low-energy electron attachment explains a number of electron-driven processes, such as anion formation in the interstellar medium and electron attachment to fullerenes.
Asymmetric transfer hydrogenation by synthetic catalysts in cancer cells Nat. Chem. (IF 25.87) Pub Date : 2018-01-08 James P. C. Coverdale, Isolda Romero-Canelón, Carlos Sanchez-Cano, Guy J. Clarkson, Abraha Habtemariam, Martin Wills, Peter J. Sadler
Catalytic anticancer metallodrugs active at low doses could minimize side-effects, introduce novel mechanisms of action that combat resistance and widen the spectrum of anticancer-drug activity. Here we use highly stable chiral half-sandwich organometallic Os(II) arene sulfonyl diamine complexes, [Os(arene)(TsDPEN)] (TsDPEN, N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine), to achieve a highly enantioselective reduction of pyruvate, a key intermediate in metabolic pathways. Reduction is shown both in aqueous model systems and in human cancer cells, with non-toxic concentrations of sodium formate used as a hydride source. The catalytic mechanism generates selectivity towards ovarian cancer cells versus non-cancerous fibroblasts (both ovarian and lung), which are commonly used as models of healthy proliferating cells. The formate precursor N-formylmethionine was explored as an alternative to formate in PC3 prostate cancer cells, which are known to overexpress a deformylase enzyme. Transfer-hydrogenation catalysts that generate reductive stress in cancer cells offer a new approach to cancer therapy.
Pt/Cu single-atom alloys as coke-resistant catalysts for efficient C–H activation Nat. Chem. (IF 25.87) Pub Date : Matthew D. Marcinkowski, Matthew T. Darby, Jilei Liu, Joshua M. Wimble, Felicia R. Lucci, Sungsik Lee, Angelos Michaelides, Maria Flytzani-Stephanopoulos, Michail Stamatakis, E. Charles H. Sykes
The recent availability of shale gas has led to a renewed interest in C–H bond activation as the first step towards the synthesis of fuels and fine chemicals. Heterogeneous catalysts based on Ni and Pt can perform this chemistry, but deactivate easily due to coke formation. Cu-based catalysts are not practical due to high C–H activation barriers, but their weaker binding to adsorbates offers resilience to coking. Using Pt/Cu single-atom alloys (SAAs), we examine C–H activation in a number of systems including methyl groups, methane and butane using a combination of simulations, surface science and catalysis studies. We find that Pt/Cu SAAs activate C–H bonds more efficiently than Cu, are stable for days under realistic operating conditions, and avoid the problem of coking typically encountered with Pt. Pt/Cu SAAs therefore offer a new approach to coke-resistant C–H activation chemistry, with the added economic benefit that the precious metal is diluted at the atomic limit.
Direct observation of the influence of cardiolipin and antibiotics on lipid II binding to MurJ Nat. Chem. (IF 25.87) Pub Date : Jani Reddy Bolla, Joshua B. Sauer, Di Wu, Shahid Mehmood, Timothy M. Allison, Carol V. Robinson
Translocation of lipid II across the cytoplasmic membrane is essential in peptidoglycan biogenesis. Although most steps are understood, identifying the lipid II flippase has yielded conflicting results, and the lipid II binding properties of two candidate flippases—MurJ and FtsW—remain largely unknown. Here we apply native mass spectrometry to both proteins and characterize lipid II binding. We observed lower levels of lipid II binding to FtsW compared to MurJ, consistent with MurJ having a higher affinity. Site-directed mutagenesis of MurJ suggests that mutations at A29 and D269 attenuate lipid II binding to MurJ, whereas chemical modification of A29 eliminates binding. The antibiotic ramoplanin dissociates lipid II from MurJ, whereas vancomycin binds to form a stable complex with MurJ:lipid II. Furthermore, we reveal cardiolipins associate with MurJ but not FtsW, and exogenous cardiolipins reduce lipid II binding to MurJ. These observations provide insights into determinants of lipid II binding to MurJ and suggest roles for endogenous lipids in regulating substrate binding.
Palladium-catalysed anti-Markovnikov selective oxidative amination Nat. Chem. (IF 25.87) Pub Date : 2018-01-01 Daniel G. Kohler, Samuel N. Gockel, Jennifer L. Kennemur, Peter J. Waller, Kami L. Hull
In recent years, the synthesis of amines and other nitrogen-containing motifs has been a major area of research in organic chemistry because they are widely represented in biologically active molecules. Current strategies rely on a multistep approach and require one reactant to be activated prior to the carbon–nitrogen bond formation. This leads to a reaction inefficiency and functional group intolerance. As such, a general approach to the synthesis of nitrogen-containing compounds from readily available and benign starting materials is highly desirable. Here we present a palladium-catalysed oxidative amination reaction in which the addition of the nitrogen occurs at the less-substituted carbon of a double bond, in what is known as anti-Markovnikov selectivity. Alkenes are shown to react with imides in the presence of a palladate catalyst to generate the terminal imide through trans-aminopalladation. Subsequently, olefin isomerization occurs to afford the thermodynamically favoured products. Both the scope of the transformation and mechanistic investigations are reported.
An integrated native mass spectrometry and top-down proteomics method that connects sequence to structure and function of macromolecular complexes Nat. Chem. (IF 25.87) Pub Date : 2018-01-01 Huilin Li, Hong Hanh Nguyen, Rachel R. Ogorzalek Loo, Iain D. G. Campuzano, Joseph A. Loo
Mass spectrometry (MS) has become a crucial technique for the analysis of protein complexes. Native MS has traditionally examined protein subunit arrangements, while proteomics MS has focused on sequence identification. These two techniques are usually performed separately without taking advantage of the synergies between them. Here we describe the development of an integrated native MS and top-down proteomics method using Fourier-transform ion cyclotron resonance (FTICR) to analyse macromolecular protein complexes in a single experiment. We address previous concerns of employing FTICR MS to measure large macromolecular complexes by demonstrating the detection of complexes up to 1.8 MDa, and we demonstrate the efficacy of this technique for direct acquirement of sequence to higher-order structural information with several large complexes. We then summarize the unique functionalities of different activation/dissociation techniques. The platform expands the ability of MS to integrate proteomics and structural biology to provide insights into protein structure, function and regulation.
Labelling and determination of the energy in reactive intermediates in solution enabled by energy-dependent reaction selectivity Nat. Chem. (IF 25.87) Pub Date : 2018-01-01 Hiroaki Kurouchi, Daniel A. Singleton
Any long-lived chemical structure in solution is subject to statistical energy equilibration, so the history of any specific structure does not affect its subsequent reactions. This is not true for very short-lived intermediates because energy equilibration takes time. Here, this idea is applied to achieve the ‘energy labelling’ of a reactive intermediate. The selectivity of the ring-opening α-cleavage reaction of the 1-methylcyclobutoxy radical is found here to vary broadly depending on how the radical was formed. Reactions that provide little excess energy to the intermediate lead to a high selectivity in the subsequent cleavage (measured as a kinetic isotope effect), whereas reactions that provide more excess energy to the intermediate exhibit a lower selectivity. Accounting for the expected excess energy allows the prediction of the observed product ratios and, in turn, the product ratios can be used to determine the energy present in an intermediate.
Acceleration of a ground-state reaction by selective femtosecond-infrared-laser-pulse excitation Nat. Chem. (IF 25.87) Pub Date : 2018-01-01 Till Stensitzki, Yang Yang, Valeri Kozich, Ashour A. Ahmed, Florian Kössl, Oliver Kühn, Karsten Heyne
Infrared (IR) excitation of vibrations that participate in the reaction coordinate of an otherwise thermally driven chemical reaction are believed to lead to its acceleration. Attempts at the practical realization of this concept have been hampered so far by competing processes leading to sample heating. Here we demonstrate, using femtosecond IR-pump IR-probe experiments, the acceleration of urethane and polyurethane formation due to vibrational excitation of the reactants for 1:1 mixtures of phenylisocyanate and cyclohexanol, and toluene-2,4-diisocyanate and 2,2,2-trichloroethane-1,1-diol, respectively. We measured reaction rate changes upon selective vibrational excitation with negligible heating of the sample and observed an increase of the reaction rate up to 24%. The observation is rationalized using reactant and transition-state structures obtained from quantum chemical calculations. We subsequently used IR-driven reaction acceleration to write a polyurethane square on sample windows using a femtosecond IR pulse.
Terbium glows green Nat. Chem. (IF 25.87) Pub Date : 2017-12-19 Geng Deng
Terbium glows green Terbium glows green, Published online: 19 December 2017; doi:10.1038/nchem.2914 Geng Deng relates how terbium, a garden-variety lanthanide, has found its way into our daily lives owing to its green fluorescence.
Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry Nat. Chem. (IF 25.87) Pub Date : 2017-12-19 Paul S. Cremer, Amar H. Flood, Bruce C. Gibb, David L. Mobley
On planet Earth, water is everywhere: the majority of the surface is covered with it; it is a key component of all life; its vapour and droplets fill the lower atmosphere; and even rocks contain it and undergo geomorphological changes because of it. A community of physical scientists largely drives studies of the chemistry of water and aqueous solutions, with expertise in biochemistry, spectroscopy and computer modelling. More recently, however, supramolecular chemists — with their expertise in macrocyclic synthesis and measuring supramolecular interactions — have renewed their interest in water-mediated non-covalent interactions. These two groups offer complementary expertise that, if harnessed, offer to accelerate our understanding of aqueous supramolecular chemistry and water writ large. This Review summarizes the state-of-the-art of the two fields, and highlights where there is latent chemical space for collaborative exploration by the two groups.
Erratum: Glucose-responsive insulin by molecular and physical design Nat. Chem. (IF 25.87) Pub Date : 2017-12-19 Naveed A. Bakh, Abel B. Cortinas, Michael A. Weiss, Robert S. Langer, Daniel G. Anderson, Zhen Gu, Sanjoy Dutta, Michael S. Strano
Erratum: Glucose-responsive insulin by molecular and physical design Erratum: Glucose-responsive insulin by molecular and physical design, Published online: 19 December 2017; doi:10.1038/nchem.2898 Erratum: Glucose-responsive insulin by molecular and physical design
Flexible molecular materials: Stressed out crystals Nat. Chem. (IF 25.87) Pub Date : 2017-12-19 Bart Kahr, Michael D. Ward
Flexible molecular materials: Stressed out crystals Flexible molecular materials: Stressed out crystals, Published online: 19 December 2017; doi:10.1038/nchem.2913 Molecular crystals have recently started to shake their inflexible reputation. Now, copper(II) acetylacetonate needles have been shown to be very flexible, and their mechanical deformation has been assessed through materials constants using methods customarily reserved for non-molecular materials.
Water splitting: Passing the acid test Nat. Chem. (IF 25.87) Pub Date : 2017-12-19 Qiushi Yin, Craig L. Hill
Water splitting: Passing the acid test Water splitting: Passing the acid test, Published online: 19 December 2017; doi:10.1038/nchem.2921 Water-oxidation catalysts that are fast and efficient in strong acid are rare even though there are several benefits for systems working at low pH. Such catalysts usually feature expensive noble metals such as ruthenium and iridum; however, an electrocatalytic system that is exceptionally efficient and based on cobalt has now been developed.
Thermally activated delayed photoluminescence from pyrenyl-functionalized CdSe quantum dots Nat. Chem. (IF 25.87) Pub Date : 2017-12-18 Cédric Mongin, Pavel Moroz, Mikhail Zamkov, Felix N. Castellano
Thermally activated delayed photoluminescence from pyrenyl-functionalized CdSe quantum dots Thermally activated delayed photoluminescence from pyrenyl-functionalized CdSe quantum dots, Published online: 18 December 2017; doi:10.1038/nchem.2906 The ability to merge the photophysical properties of semiconductor quantum dots with those of well-understood and inexpensive molecular chromophores is important for the development of various emerging photonic and optoelectronic technologies. Now, 1-pyrenecarboxylic acid-functionalized CdSe quantum dots have been shown to undergo thermally activated delayed photoluminescence and display tunable photophysical properties.
Substrate-driven chemotactic assembly in an enzyme cascade Nat. Chem. (IF 25.87) Pub Date : 2017-12-18 Xi Zhao, Henri Palacci, Vinita Yadav, Michelle M. Spiering, Michael K. Gilson, Peter J. Butler, Henry Hess, Stephen J. Benkovic, Ayusman Sen
Substrate-driven chemotactic assembly in an enzyme cascade Substrate-driven chemotactic assembly in an enzyme cascade, Published online: 18 December 2017; doi:10.1038/nchem.2905 Enzymes that form a metabolic pathway in which the product of one enzyme is the substrate for the next have now been shown to associate through a process of sequential, directed chemotactic movement. The extent of enzyme migration is proportional to the exposure time to the substrate gradient.
Iridium-catalysed arylation of C–H bonds enabled by oxidatively induced reductive elimination Nat. Chem. (IF 25.87) Pub Date : 2017-12-11 Kwangmin Shin, Yoonsu Park, Mu-Hyun Baik, Sukbok Chang
Iridium-catalysed arylation of C–H bonds enabled by oxidatively induced reductive elimination Iridium-catalysed arylation of C–H bonds enabled by oxidatively induced reductive elimination, Published online: 11 December 2017; doi:10.1038/nchem.2900 The direct arylation of C–H bonds is an attractive synthetic step, but the reductive elimination of an organometallic catalyst carrying the desired C–H and aryl functionalities has remained challenging. Now, this step has been achieved by first oxidizing the iridium centre of the catalyst, which facilitates the arylation of arene C–H bonds of a range of substrates.
The role of uranium–arene bonding in H2O reduction catalysis Nat. Chem. (IF 25.87) Pub Date : 2017-12-11 Dominik P. Halter, Frank W. Heinemann, Laurent Maron, Karsten Meyer
The role of uranium–arene bonding in H2O reduction catalysis The role of uranium–arene bonding in H2O reduction catalysis, Published online: 11 December 2017; doi:10.1038/nchem.2899 An arene-anchored uranium(III) complex that facilitates the electrocatalytic formation of H2 from H2O has now been shown to involve redox-cooperativity between the uranium centre and its covalently bound mesitylene ligand. The oxidative addition of H2O to the uranium catalyst is a concerted two-electron reaction — atypical for f-block metals.
De novo design and engineering of non-ribosomal peptide synthetases Nat. Chem. (IF 25.87) Pub Date : 2017-12-11 Kenan A. J. Bozhüyük, Florian Fleischhacker, Annabell Linck, Frank Wesche, Andreas Tietze, Claus-Peter Niesert, Helge B. Bode
De novo design and engineering of non-ribosomal peptide synthetases De novo design and engineering of non-ribosomal peptide synthetases, Published online: 11 December 2017; doi:10.1038/nchem.2890 Peptides derived from non-ribosomal peptide synthetases (NRPS) are an important class of pharmaceutically relevant drugs. However, no general rules for the modification of NRPS or the generation of artificial NRPS are known. Now, a new strategy for the modification of NRPS has been developed that uses defined exchange units that are fused at specific positions connecting the condensation and adenylation domains.
A general approach to intermolecular carbonylation of arene C–H bonds to ketones through catalytic aroyl triflate formation Nat. Chem. (IF 25.87) Pub Date : 2017-12-11 R. Garrison Kinney, Jevgenijs Tjutrins, Gerardo M. Torres, Nina Jiabao Liu, Omkar Kulkarni, Bruce A. Arndtsen
A general approach to intermolecular carbonylation of arene C–H bonds to ketones through catalytic aroyl triflate formation A general approach to intermolecular carbonylation of arene C–H bonds to ketones through catalytic aroyl triflate formation, Published online: 11 December 2017; doi:10.1038/nchem.2903 Catalytic transformations that incorporate carbonyl functional groups in arene C–H bonds have remained limited, despite being attractive synthetic steps. Now, the intermolecular carbonylative coupling of a broad range of simple arenes into ketones has been developed. The reaction occurs through the palladium-catalysed generation of high-energy aroyl triflate electrophiles.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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