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51.
Back Cover: Switch‐On Fluorescence of a Perylene‐Dye‐Functionalized Metal–Organic Framework through Postsynthetic Modification (Chem. Eur. J. 30/2015) 下载免费PDF全文
52.
Dr. James R. Frost Prof. Dr. Stefan M. Huber Dr. Stefan Breitenlechner M. Sc. Christoph Bannwarth Prof. Dr. Thorsten Bach 《Angewandte Chemie (International ed. in English)》2015,54(2):691-695
Spirocyclic oxindoles undergo an enantioselective oxygenation reaction (nine examples; e.r. up to 97:3) upon catalysis by a chiral ruthenium porphyrin complex (1 mol %). The catalyst exhibits a lactam ring, which is responsible for substrate association through hydrogen bonds, and an active ruthenium center, which is in a defined spatial relationship to the oxygenation substrate. DFT calculations illustrate the perfect alignment of the active site with the reactive C? H bond and suggest—in line with the kinetic isotope effect—an oxygen rebound mechanism for the reaction. 相似文献
53.
Total Synthesis of Albicidin: A Lead Structure from Xanthomonas albilineans for Potent Antibacterial Gyrase Inhibitors 下载免费PDF全文
Julian Kretz Dennis Kerwat Vivien Schubert Stefan Grätz Alexander Pesic Siamak Semsary Stéphane Cociancich Monique Royer Prof. Dr. Roderich D. Süssmuth 《Angewandte Chemie (International ed. in English)》2015,54(6):1969-1973
The peptide antibiotic albicidin, which is synthesized by the plant pathogenic bacterium Xanthomonas albilineans, displays remarkable antibacterial activity against various Gram‐positive and Gram‐negative microorganisms. The low amounts of albicidin obtainable from the producing organism or through heterologous expression are limiting factors in providing sufficient material for bioactivity profiling and structure–activity studies. Therefore, we developed a convergent total synthesis route toward albicidin. The unexpectedly difficult formation of amide bonds between the aromatic amino acids was achieved through a triphosgene‐mediated coupling strategy. The herein presented synthesis of albicidin confirms the previously determined chemical structure and underlines the extraordinary antibacterial activity of this compound. The synthetic protocol will provide multigram amounts of albicidin for further profiling of its drug properties. 相似文献
54.
Dr. Guang‐Ping Hao Giovanni Mondin Dr. Zhikun Zheng Tim Biemelt Stefan Klosz René Schubel Prof. Alexander Eychmüller Prof. Stefan Kaskel 《Angewandte Chemie (International ed. in English)》2015,54(6):1941-1945
There is significant interest in high‐performance materials that can directly and efficiently capture water vapor, particularly from air. Herein, we report a class of novel porous carbon cuboids with unusual ultra‐hydrophilic properties, over which the synergistic effects between surface heterogeneity and micropore architecture is maximized, leading to the best atmospheric water‐capture performance among porous carbons to date, with a water capacity of up to 9.82 mmol g?1 at P/P0=0.2 and 25 °C (20 % relative humidity or 6000 ppm). Benefiting from properties, such as defined morphology, narrow pore size distribution, and high heterogeneity, this series of functional carbons may serve as model materials for fundamental research on carbon chemistry and the advance of new types of materials for water‐vapor capture as well as other applications requiring combined highly hydrophilic surface chemistry, developed hierarchical porosity, and excellent stability. 相似文献
55.
Structural Characterization of O‐ and C‐Glycosylating Variants of the Landomycin Glycosyltransferase LanGT2 下载免费PDF全文
Dr. Heng Keat Tam Dr. Johannes Härle Dr. Stefan Gerhardt Prof. Dr. Jürgen Rohr Guojun Wang Prof. Dr. Jon S. Thorson Dr. Aurélien Bigot Monika Lutterbeck Dr. Wolfgang Seiche Prof. Dr. Bernhard Breit Prof. Dr. Andreas Bechthold Prof. Dr. Oliver Einsle 《Angewandte Chemie (International ed. in English)》2015,54(9):2811-2815
The structures of the O‐glycosyltransferase LanGT2 and the engineered, C? C bond‐forming variant LanGT2S8Ac show how the replacement of a single loop can change the functionality of the enzyme. Crystal structures of the enzymes in complex with a nonhydrolyzable nucleotide‐sugar analogue revealed that there is a conformational transition to create the binding sites for the aglycon substrate. This induced‐fit transition was explored by molecular docking experiments with various aglycon substrates. 相似文献
56.
57.
Structure Elucidation and Activity of Kolossin A,the D‐/L‐Pentadecapeptide Product of a Giant Nonribosomal Peptide Synthetase 下载免费PDF全文
Prof. Dr. Helge B. Bode Dr. Alexander O. Brachmann Dr. Kirtikumar B. Jadhav Dr. Lydia Seyfarth Dipl.‐Chem. Christina Dauth Dr. Sebastian W. Fuchs Dr. Marcel Kaiser Dr. Nick R. Waterfield Dipl.‐Phys. Holger Sack Prof. Dr. Stefan H. Heinemann Prof. Dr. Hans‐Dieter Arndt 《Angewandte Chemie (International ed. in English)》2015,54(35):10352-10355
The largest continuous bacterial nonribosomal peptide synthetase discovered so far is described. It consists of 15 consecutive modules arising from an uninterrupted, fully functional gene in the entomopathogenic bacterium Photorhabdus luminescens. The identification of its cryptic biosynthesis product was achieved by using a combination of genome analysis, promoter exchange, isotopic labeling experiments, and total synthesis of a focused collection of peptide candidates. Although it belongs to the growing class of D ‐/ L ‐peptide natural products, the encoded metabolite kolossin A was found to be largely devoid of antibiotic activity and is likely involved in interspecies communication. A stereoisomer of this peculiar natural product displayed high activity against Trypanosoma brucei rhodesiense, a recalcitrant parasite that causes the deadly disease African sleeping sickness. 相似文献
58.
Dr. Michael Georg Hoesl M. Sc. Stefan Oehm Dr. Patrick Durkin Dr. Elise Darmon Dr. Lauri Peil Dr. Hans‐Rudolf Aerni Prof. Dr. Juri Rappsilber Prof. Dr. Jesse Rinehart Prof. Dr. David Leach Prof. Dr. Dieter Söll Prof. Dr. Nediljko Budisa 《Angewandte Chemie (International ed. in English)》2015,54(34):10030-10034
We have changed the amino acid set of the genetic code of Escherichia coli by evolving cultures capable of growing on the synthetic noncanonical amino acid L ‐β‐(thieno[3,2‐b]pyrrolyl)alanine ([3,2]Tpa) as a sole surrogate for the canonical amino acid L ‐tryptophan (Trp). A long‐term cultivation experiment in defined synthetic media resulted in the evolution of cells capable of surviving Trp→[3,2]Tpa substitutions in their proteomes in response to the 20 899 TGG codons of the E. coli W3110 genome. These evolved bacteria with new‐to‐nature amino acid composition showed robust growth in the complete absence of Trp. Our experimental results illustrate an approach for the evolution of synthetic cells with alternative biochemical building blocks. 相似文献
59.
Prof. Dr. Holger Braunschweig Theresa Dellermann Dr. William C. Ewing Thomas Kramer Christoph Schneider Stefan Ullrich 《Angewandte Chemie (International ed. in English)》2015,54(35):10271-10275
The syntheses of sulfur‐ and selenium‐bridged cyclic compounds containing boron stabilized by N‐heterocyclic carbenes (NHCs) have been achieved by the reductive insertion of elemental chalcogens into boron–boron multiple bonds. The three pairs of bonding electrons between the boron atoms in the triply bonded diboryne enabled six‐electron reduction reactions, resulting in the formation of [2.2.1]‐bicyclic systems wherein bridgehead boron atoms are spanned by three chalcogen bridges. A similar reaction using a diborene (boron–boron double bond) resulted in the reductive transfer of both pairs of bonding electrons to three sulfur atoms, yielding a NHC‐stabilized trisulfidodiborolane. The demonstration of these six‐ and four‐electron reductions lends support to the presence of three and two pairs of bonding electrons between the boron atoms of the diboryne and diborene, respectively, a fact that may be useful in future discussions on bond order. 相似文献
60.
Locked by Design: A Conformationally Constrained Transglutaminase Tag Enables Efficient Site‐Specific Conjugation 下载免费PDF全文
Dr. Vanessa Siegmund Dr. Stefan Schmelz Stephan Dickgiesser Jan Beck Aileen Ebenig Heiko Fittler Dr. Holm Frauendorf Dr. Birgit Piater Dr. Ulrich A. K. Betz Dr. Olga Avrutina Dr. Andrea Scrima Prof. Dr. Hans‐Lothar Fuchsbauer Prof. Dr. Harald Kolmar 《Angewandte Chemie (International ed. in English)》2015,54(45):13420-13424
Based on the crystal structure of a natural protein substrate for microbial transglutaminase, an enzyme that catalyzes protein crosslinking, a recognition motif for site‐specific conjugation was rationally designed. Conformationally locked by an intramolecular disulfide bond, this structural mimic of a native conjugation site ensured efficient conjugation of a reporter cargo to the therapeutic monoclonal antibody cetuximab without erosion of its binding properties. 相似文献