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Laurent Mirolo Tobias Schmidt Dr. Sonja Eckhardt Prof. Dr. Markus Meuwly Prof. Dr. Katharina M. Fromm 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(5):1754-1761
Artificial implants and biomaterials lack the natural defense system of our body and, thus, have to be protected from bacterial adhesion and biofilm formation. In addition to the increasing number of implanted objects, the resistance of bacteria is also an important problem. Silver ions are well‐known for their antimicrobial properties, yet not a lot is known about their mode of action. Silver is expected to interact on many levels, thus the development of silver resistance is very difficult. Nevertheless, some bacteria are able to resist silver, even at higher concentrations. One such defense mechanism of bacteria against heavy‐metal intoxication includes an efflux system. SilE, a periplasmic silver‐binding protein that is involved in this defense mechanism, has been shown to possess numerous histidine functions, which strongly bind to silver atoms, as demonstrated by ourselves previously. Herein, we address the question of how histidine binds to silver ions as a function of pH value. This property is important because the local proton concentration in cells varies. Thus, we solved the crystal structures of histidine–silver complexes at different pH values and also investigated the influence of the amino‐acid configuration. These results were completed by DFT calculations on the binding strength and packing effects and led to the development of a model for the mode of action of SilE. 相似文献
34.
Eva Zahorska Francesca Rosato Kai Stober Sakonwan Kuhaudomlarp Joscha Meiers Dirk Hauck Dorina Reith Emilie Gillon Katharina Rox Anne Imberty Winfried Römer Alexander Titz 《Angewandte Chemie (International ed. in English)》2023,62(7):e202215535
Bacterial adhesion, biofilm formation and host cell invasion of the ESKAPE pathogen Pseudomonas aeruginosa require the tetravalent lectins LecA and LecB, which are therefore drug targets to fight these infections. Recently, we have reported highly potent divalent galactosides as specific LecA inhibitors. However, they suffered from very low solubility and an intrinsic chemical instability due to two acylhydrazone motifs, which precluded further biological evaluation. Here, we isosterically substituted the acylhydrazones and systematically varied linker identity and length between the two galactosides necessary for LecA binding. The optimized divalent LecA ligands showed improved stability and were up to 1000-fold more soluble. Importantly, these properties now enabled their biological characterization. The lead compound L2 potently inhibited LecA binding to lung epithelial cells, restored wound closure in a scratch assay and reduced the invasiveness of P. aeruginosa into host cells. 相似文献
35.
Georgios Papazoglou Jorge Sierra Katharina Homberger Armin Guggisberg Wolf-Dietrich Woggon Manfred Hesse 《Helvetica chimica acta》1991,74(3):565-571
Aphelandrine ( 1 ) is shown to be biosynthesized in the root cells of Aphelandra tetragona (VAHL ) NEES from labelled putrescine ( 4 ), spermidine ( 5 ), and cinnamic acid ( 3 ). Whether spermine ( 6 ) and the (p-hydroxycinnamoyl)spermidine 8 are precursors of 1 is uncertain, since the latter is hydrolysed to a large extent before incorporation, and the former is metabolized to 4 and 5 . Methionine ( 7 ) is the source of the 3-aminopropyl unit of 5 and 6 . 相似文献
36.
John D. Mertens Katharina Kohse-Hinghaus Ronald K. Hanson Craig T. Bowman 《国际化学动力学杂志》1991,23(8):655-668
The reaction of atomic hydrogen with isocyanic acid (HNCO) to produce the amidogen radical (NH2) and carbon monoxide, has been studied in shock-heated mixtures of HNCO dilute in argon. Time-histories of the ground-state NH2 radical were measured behind reflected shock waves using cw, narrowlinewidth laser absorption at 597 nm, and HNCO time-histories were measured using infrared emission from the fundamental v2-band of HNCO near 5 μm. The second-order rate coefficient of reaction (2(a)) was determined to be: cm3 mol?1 s?1, where f and F define the lower and upper uncertainty limits, respectively. An upper limit on the rate coefficient of was determined to be: 相似文献
37.
(NH4)2[Mo6Cl14] · H2O ( 1 ) was prepared from reactions of MoCl2 in ethanol with aqueous NH4Cl solution. It crystallizes in the monoclinic space group I2/a (no. 15), Z = 4 with a = 912.3(1), b = 1491.2(2), c = 1724.8(2) pm, β = 92.25(1)°; R1 = 0.023 (based on F values) and wR2 = 0.059 (based on F2 values), for all measured X‐ray reflections. The structure of the cluster anion can be given as [(Mo6Cl)Cl]2– (i = inner, a = outer ligands). Thermal stability studies show that 1 loses crystal water followed by the loss of NH4Cl above 350 °C to yield MoCl2. The water‐free compound (NH4)2[Mo6Cl14] ( 2 ) was synthesized by solid state reaction of MoCl2 and NH4Cl in a sealed quartz ampoule at 270 °C. No single‐crystals could be obtained. Decompositions of 1 and 2 under nitrogen and argon exhibited the loss of NH4Cl at about 350 °C. Decomposition under NH3 resulted in the formation of MoN and Mo2N at 540 °C and 720 °C, respectively. 相似文献
38.
Stieghorst Christian Hampel Gabriele Karches Barbara Krenckel Patricia Kudějová Petra Plonka Christian Révay Zsolt Riepe Stephan Welter Katharina Wiehl Norbert 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):307-313
Journal of Radioanalytical and Nuclear Chemistry - For the optimization of the manufacturing process of multicrystalline silicon (mc-Si) for solar cells in order to reduce energy consumption and... 相似文献
39.
Prof. Dr. Petra Schwille Prof. Dr. Joachim Spatz Prof. Dr. Katharina Landfester Prof. Dr. Eberhard Bodenschatz Prof. Dr. Stephan Herminghaus Prof. Dr. Victor Sourjik Dr. Tobias J. Erb Prof. Dr. Philippe Bastiaens Prof. Dr. Reinhard Lipowsky Prof. Dr. Anthony Hyman Prof. Dr. Peter Dabrock Dr. Jean‐Christophe Baret Dr. Tanja Vidakovic‐Koch Dr. Peter Bieling Dr. Rumiana Dimova Dr. Hannes Mutschler Dr. Tom Robinson Dr. T.‐Y. Dora Tang Dr. Seraphine Wegner Prof. Dr. Kai Sundmacher 《Angewandte Chemie (International ed. in English)》2018,57(41):13382-13392
A large German research consortium mainly within the Max Planck Society (“MaxSynBio”) was formed to investigate living systems from a fundamental perspective. The research program of MaxSynBio relies solely on the bottom‐up approach to synthetic biology. MaxSynBio focuses on the detailed analysis and understanding of essential processes of life through modular reconstitution in minimal synthetic systems. The ultimate goal is to construct a basic living unit entirely from non‐living components. The fundamental insights gained from the activities in MaxSynBio could eventually be utilized for establishing a new generation of biotechnological processes, which would be based on synthetic cell constructs that replace the natural cells currently used in conventional biotechnology. 相似文献
40.
Dr. Robert Lizatović Marvin Assent Arjan Barendregt Jonathan Dahlin Dr. Anna Bille Katharina Satzinger Dagnija Tupina Prof. Albert J. R. Heck Dr. Stefan Wennmalm Dr. Ingemar André 《Angewandte Chemie (International ed. in English)》2018,57(35):11334-11338
Protein‐based encapsulation systems have a wide spectrum of applications in targeted delivery of cargo molecules and for chemical transformations in confined spaces. By engineering affinity between cargo and container proteins it has been possible to enable the efficient and specific encapsulation of target molecules. Missing in current approaches is the ability to turn off the interaction after encapsulation to enable the cargo to freely diffuse in the lumen of the container. Separation between cargo and container is desirable in drug delivery applications and in the use of capsids as catalytic nanoparticles. We describe an encapsulation system based on the hepatitis B virus capsid in which an engineered high‐affinity interaction between cargo and capsid proteins can be modulated by Ca2+. Cargo proteins are loaded into capsids in the presence of Ca2+, while ligand removal triggers unbinding inside the container. We observe that confinement leads to hindered rotation of cargo inside the capsid. Application of the designed container for catalysis was also demonstrated by encapsulation of an enzyme with β‐glucosidase activity. 相似文献