Volume 10 Issue 8, August 2018

Volume 10 Issue 8

Catalytic site seeing

There are a number of factors that control product selectivity and catalyst lifetime in acid-catalysed reactions using zeolites. Now, by analysing the catalytic behavior of zeolites with different textural and acidic properties, a team led by Jorge Gascon has developed structure–performance descriptors for the methanol-to-propylene process. They have shown that Brønsted acidity is key for propylene selectivity and that Lewis acidity is responsible for prolonging the lifetime of the catalyst. The image on the cover is an artistic representation of the zeolitic microenvironment, inhabited by methanol and olefins interacting with each other.

See Gascon et al.

Image: Ella Maru Studio. Cover design: Tulsi Voralia

Thesis

  • Thesis |

    Bruce C. Gibb takes us on a journey through the physical and chemical evolution of planet Earth and suggests that the reverse Hofmeister effect, the phenomenon whereby poorly solvated ions associate in water, could be a powerful driving force towards the first hint of life on the rock we call home.

    • Bruce C. Gibb

News & Views

  • News & Views |

    Potassium channels rapidly move K+ ions across cell membranes while blocking Na+, but how these two effects are achieved simultaneously has remained unclear. Now, extensive molecular simulations show a single mechanism that features fully dehydrated ions can explain both rapid transport and impeccable selectivity.

    • Ben Corry
  • News & Views |

    Enzymes can perform various biological functions because of their delicately and precisely organized structures. Now, simple inorganic nanoparticles with a rationally designed recognition capability can mimic restriction enzymes and selectively cut specific DNA sequences.

    • Aleksandar P. Ivanov
    •  & Joshua B. Edel
  • News & Views |

    A new pyrrolysyl-tRNA synthetase/PyltRNA (PylRS/PyltRNA) pair that is mutually orthogonal to existing PylRS/PyltRNA pairs has now been discovered and optimized. This system could enable the site-specific incorporation of a greater number of distinct non-canonical amino acids into a protein.

    • William S. C. Ngai
    •  & Peng R. Chen

Articles

  • Article |

    As of yet, no clear structure–performance descriptors have been developed to tune the catalytic activity of zeolitic methanol-to-olefin catalysts. Now it has been shown that introducing Lewis acidity into Brønsted acidic zeolites boosts their performance. Although Brønsted acidity is found to define propylene selectivity, Lewis acidity is responsible for prolonging lifetime.

    • Irina Yarulina
    • , Kristof De Wispelaere
    • , Simon Bailleul
    • , Joris Goetze
    • , Mike Radersma
    • , Edy Abou-Hamad
    • , Ina Vollmer
    • , Maarten Goesten
    • , Brahim Mezari
    • , Emiel J. M. Hensen
    • , Juan S. Martínez-Espín
    • , Magnus Morten
    • , Sharon Mitchell
    • , Javier Perez-Ramirez
    • , Unni Olsbye
    • , Bert M. Weckhuysen
    • , Veronique Van Speybroeck
    • , Freek Kapteijn
    •  & Jorge Gascon
  • Article |

    That K+ channels conduct K+ ions at near-diffusion limited rates, but block the passage of smaller Na+ ions, creates an apparent contradiction. Now, atomistic simulations and free-energy calculations are used to show that both K+ permeation and ion selectivity are governed by the direct knock-on of completely desolvated ions in the channels’ selectivity filter.

    • Wojciech Kopec
    • , David A. Köpfer
    • , Owen N. Vickery
    • , Anna S. Bondarenko
    • , Thomas L. C. Jansen
    • , Bert L. de Groot
    •  & Ulrich Zachariae
  • Article |

    Genome editing relies on engineered nucleases to change an organism’s DNA, but has not yet been achieved using abiotic materials. Now, chiral cysteine-capped CdTe nanoparticles are found to specifically recognize and, following photoirradiation, cut between bases T and A at the GATATC restriction site in DNA with over 90 base pairs.

    • Maozhong Sun
    • , Liguang Xu
    • , Aihua Qu
    • , Peng Zhao
    • , Tiantian Hao
    • , Wei Ma
    • , Changlong Hao
    • , Xiaodong Wen
    • , Felippe M. Colombari
    • , Andre F. de Moura
    • , Nicholas A. Kotov
    • , Chuanlai Xu
    •  & Hua Kuang
  • Article |

    Pyrrolysyl-tRNA synthetase(PylRS)/PyltRNACUA pairs that lack the N-terminal domain but are active and orthogonal are discovered, and pairs that are mutually orthogonal to existing PylRS/PyltRNACUA pairs are developed. Mutually orthogonal PylRS/PyltRNA pairs are combined to genetically encode the incorporation of distinct ncAAs into proteins synthesized in E. coli.

    • Julian C. W. Willis
    •  & Jason W. Chin
  • Article |

    Understanding the mechanism of photoconversion in fluorescent proteins is essential to optimizing applications in imaging and optogenetics. It has now been demonstrated that photoconversion in the photoswitchable protein dronpa follows a multi-step mechanism, with both chromophore and protein structural dynamics occurring on multiple timescales from picoseconds to hundreds of microseconds.

    • Sergey P. Laptenok
    • , Agnieszka A. Gil
    • , Christopher R. Hall
    • , Andras Lukacs
    • , James N. Iuliano
    • , Garth A. Jones
    • , Gregory M. Greetham
    • , Paul Donaldson
    • , Atsushi Miyawaki
    • , Peter J. Tonge
    •  & Stephen R. Meech
  • Article |

    Atomic manipulation was used to control the reductive rearrangement of 1,1-dibromo alkenes to acetylenes on a NaCl surface at 5 K, and the stages of the reaction were visualized with atomic resolution using AFM. Polyynes ranging from triyne to octayne were prepared in this way, and STM was used to map their frontier orbitals and determine their transport gaps.

    • Niko Pavliček
    • , Przemyslaw Gawel
    • , Daniel R. Kohn
    • , Zsolt Majzik
    • , Yaoyao Xiong
    • , Gerhard Meyer
    • , Harry L. Anderson
    •  & Leo Gross
  • Article |

    As a consequence of high chemical resistance and low solubility in conventional solvents, deconstructing biomass into fuels and other useful chemical building blocks remains a challenge. Now, through enzyme modification and ionic liquid solvents, it is possible to homogeneously biocatalytically convert cellulose to sugars at a rate 30 times greater than is achievable in water.

    • Alex P. S. Brogan
    • , Liem Bui-Le
    •  & Jason P. Hallett

    Collection:

  • Article |

    Electrophilic aromatic substitution (EAS) favours arene functionalization at positions meta to electron-withdrawing groups and para to electron-donating groups. Now, with a class of bridgehead-modified norbonene derivatives that can overcome the ortho constraint typical in palladium/norbornene catalysis, arene functionalization with site-selectivity complementary to EAS approaches can be achieved.

    • Jianchun Wang
    • , Renhe Li
    • , Zhe Dong
    • , Peng Liu
    •  & Guangbin Dong
  • Article |

    The [4Fe4S]2+ cluster-containing DNA-repair enzyme MUTYH helps safeguard the integrity of Watson–Crick base pairing and the human genetic code. The MUTYH [4Fe4S]2+ cluster mediates DNA redox signalling and DNA lesion identification. Now, a MUTYH pathologic variant associated with catastrophic [4Fe4S]2+ cluster redox degradation, impairment of DNA signalling and human colonic tumorigenesis has been identified.

    • Kevin J. McDonnell
    • , Joseph A. Chemler
    • , Phillip L. Bartels
    • , Elizabeth O’Brien
    • , Monica L. Marvin
    • , Janice Ortega
    • , Ralph H. Stern
    • , Leon Raskin
    • , Guo-Min Li
    • , David H. Sherman
    • , Jacqueline K. Barton
    •  & Stephen B. Gruber
  • Article |

    A series of tungsten hydride complexes have been synthesized to mimic a proton-coupled electron transfer (PCET) step undergone by metal–hydride intermediates during solar fuel catalysis. It is shown that, by incorporating proton-accepting bases into the second coordination sphere, their PCET oxidation mechanism changes and its rate increases by several orders of magnitude.

    • Tianfei Liu
    • , Meiyuan Guo
    • , Andreas Orthaber
    • , Reiner Lomoth
    • , Marcus Lundberg
    • , Sascha Ott
    •  & Leif Hammarström
  • Article |

    Chiral tertiary aldols are encountered in a variety of biologically relevant molecules. Making these valuable compounds directly from unbiased ketones has proven to be extremely challenging. Now it has been shown that sub-ppm levels of in situ generated silylium-based organic Lewis acid catalysts can give quantitative product formation in very high enantiopurity through a Mukaiyama aldol reaction.

    • Han Yong Bae
    • , Denis Höfler
    • , Philip S. J. Kaib
    • , Pinar Kasaplar
    • , Chandra Kanta De
    • , Arno Döhring
    • , Sunggi Lee
    • , Karl Kaupmees
    • , Ivo Leito
    •  & Benjamin List

Amendments & Corrections

In Your Element

  • In Your Element |

    Vikki Cantrill tells the story of element 88’s discovery and how its glowing reputation eventually faded.

    • Vikki Cantrill