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171.
A Functional Role for Aβ in Metal Homeostasis? N‐Truncation and High‐Affinity Copper Binding
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Mariusz Mital Nina E. Wezynfeld Tomasz Frączyk Magdalena Z. Wiloch Urszula E. Wawrzyniak Arkadiusz Bonna Carolin Tumpach Kevin J. Barnham Cathryn L. Haigh Wojciech Bal Simon C. Drew 《Angewandte Chemie (International ed. in English)》2015,54(36):10460-10464
Accumulation of the β‐amyloid (Aβ) peptide in extracellular senile plaques rich in copper and zinc is a defining pathological feature of Alzheimer′s disease (AD). The Aβ1–x (x=16/28/40/42) peptides have been the primary focus of CuII binding studies for more than 15 years; however, the N‐truncated Aβ4–42 peptide is a major Aβ isoform detected in both healthy and diseased brains, and it contains a novel N‐terminal FRH sequence. Proteins with His at the third position are known to bind CuII avidly, with conditional log K values at pH 7.4 in the range of 11.0–14.6, which is much higher than that determined for Aβ1–x peptides. By using Aβ4–16 as a model, it was demonstrated that its FRH sequence stoichiometrically binds CuII with a conditional Kd value of 3×10?14 M at pH 7.4, and that both Aβ4–16 and Aβ4–42 possess negligible redox activity. Combined with the predominance of Aβ4–42 in the brain, our results suggest a physiological role for this isoform in metal homeostasis within the central nervous system. 相似文献
172.
Carolin Dusold Benedikt Platzer Philipp Haines David Reger Prof. Dr. Norbert Jux Prof. Dr. Dirk. M. Guldi Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(5):1670-1679
Synthesis and characterization of a series of rylene-diimide substituted hexaphenylbenzenes (HPBs) is presented. The direct connection of the rylene-diimide units to the HPBs via the imide-N-position without any linkers as well as the use of naphthalene-diimides (NDIs) next to perylene-diimides (PDIs) is unprecedented. While mono-substituted products were obtained by imidization reactions with amino-HPB and the respective rylene-monoimides, key step for the formation of tri- and hexa-substituted HPBs is the Co-catalysed cyclotrimerization. Particular emphasis for physic-chemical characterization was on to the number of NDIs/PDIs per HPB and the overall substitution patterns. Lastly, Scholl oxidation conditions were applied to all HPB systems to generate the corresponding hexa-peri-hexabenzocoronenes (HBCs). Importantly, the efficiency of the transformation strongly depends on the number of NDIs/PDIs. While three rylene-diimide units already hinder the Scholl reaction, the successful synthesis of mono-substituted HBCs is possible. 相似文献
173.
In this paper, a computational model for the correct simulation of an arbitrary sequence of longitudinal loading cases on coupled track-bridge systems is proposed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
174.
Ilya A. P. Jourjine Carolin Bauernschmidt Christoph Müller Franz Bracher 《Molecules (Basel, Switzerland)》2022,27(23)
The Annonaceae are an old family of flowering plants belonging to the order Magnoliales, distributed mainly in tropical regions. Numerous Annonaceae species find ethnobotanical use for curing a broad range of diseases, among them cancer and infections by diverse pathogens. Hence, bioactive natural products from Annonaceae have received considerable interest in drug development. Beyond cytotoxic acetogenins, unique aporphine-derived polycyclic aromatic alkaloids are characteristic constituents of Annonaceae. Among them are unique tri- and tetracyclic aromatic alkaloids like azafluorenones, diazafluoranthenes, azaanthracenes, and azaoxoaporphines. The complex substitution pattern of these alkaloids represents a major challenge in structure elucidation of isolated natural products. Based on a broad spectrum of alkaloids available from our previous work, we present a GC-MS protocol for the identification of over 20 polycyclic aromatic alkaloids from Annonaceae. This collection of data will contribute to the future identification of the metabolite patterns of extracts from Annonaceae as an important source of novel bioactive secondary metabolites. 相似文献
175.
176.
Dr. Jiawang Liu Ji Yang Carolin Schneider Prof. Dr. Robert Franke Dr. Ralf Jackstell Prof. Dr. Matthias Beller 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9117-9125
For the first time, the monoalkoxycarbonylation of easily available 1,3-diynes to give synthetically useful conjugated enynes has been realized. Key to success was the design and utilization of the new ligand 2,2′-bis(tert-butyl(pyridin-2-yl)phosphanyl)-1,1′-binaphthalene (Neolephos), which permits the palladium-catalyzed selective carbonylation under mild conditions, providing a general preparation of functionalized 1,3-enynes in good-to-high yields with excellent chemoselectivities. Synthetic applications that showcase the possibilities of this novel methodology include an efficient one-pot synthesis of 4-aryl-4H-pyrans as well as the rapid construction of various heterocyclic, bicyclic, and polycyclic compounds. 相似文献
177.
Carolin Dusold Philipp Haines Benedikt Platzer Prof. Dr. Dirk M. Guldi Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(21):6511-6521
Perylene- as well as naphthalenediimides were fused to hexabenzocoronenes (HBCs) at their imide position to realize highly π-extended donor–acceptor (D–A)-hybrids. Successful isomer separation in the first step was decisive to guarantee a straightforward synthetic sequence. Hexaphenylbenzenes as precursors were accessed via Diels–Alder reactions and reacted in a Scholl oxidation to yield the respective HBC derivatives. The fully conjugated benzimidazole linker, which separates the electron donating HBC from the electron accepting rylenediimide, enabled the formation of either a linear or a helical configuration. Largely different chemical, physical, and optoelectrical characteristics were noted for the two configurations. What stood out was their aggregation and their excited state deactivation depending on the solvent polarity. Results from global analysis of the femtosecond transient absorption data corroborated the formation of a charge-transfer (CT) state that is stabilized in the helically fused configuration relative to the linear analogue. However, a comparison with spectroelectrochemical experiments failed to disclose evidence for a charge-separated (CS) state. 相似文献
178.
Priv.‐Doz. Dr. Falk Harnisch Dipl.‐Ing. Carolin Urban 《Angewandte Chemie (International ed. in English)》2018,57(32):10016-10023
An integrated biobased economy urges an alliance of the two realms of “chemical production” and “electric power”. The concept of electrobiorefineries provides a blueprint for such an alliance. Joining the forces of microbial and electrochemical conversions in electrobiorefineries allows interfacing the production, storage, and exploitation of electricity as well as biobased chemicals. Electrobiorefineries are a technological evolution of biorefineries by the addition of (bio)electrochemical transformations. This interfacing of microbial and electrochemical conversions will result in synergies affecting the entire process line, like enlarging the product portfolio, increasing the productivity, or exploiting new feedstock. A special emphasis is given to the utilization of oxidative and reductive electroorganic reactions of microbially produced intermediates that may serve as privileged building blocks. 相似文献
179.
Madwar C Kwan WC Deng L Ramström O Schmidt R Zou S Cuccia LA 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):16677-16680
The versatility of perfluorophenyl azide (PFPA) derivatives makes them useful for attaching a wide variety of biomolecules and polymers to surfaces. Herein, a single molecule force spectroscopy (SMFS) study of the concanavalin A/mannose interaction was carried out using PFPA immobilization chemistry. SMFS of the concanavalin A/mannose interaction yielded an average unbinding force of 70-80 pN for loading rates between 8000 and 40,000 pN/s for mannose surfaces on aminated glass, and an unbinding force of 57 ± 20 pN at 6960 pN/s for mannose surfaces on gold-coated glass. Dynamic force spectroscopy was used to determine the dissociation rate constant, k(off), for this interaction to be 0.16 s(-1). 相似文献
180.
Seung Tae Hong Jin-Woo Kim Won-Ho Jang Jong Sung Lim Hyung Sang Park Ki-Pung Yoo Carolin Apfel Wolfgang Arlt 《Research on Chemical Intermediates》2009,35(2):197-207
The transesterification of palm oil in supercritical methanol has been investigated without using any catalyst. HCFC-141b
was used as co-solvent to reduce the molar ratio of methanol to palm oil under the milder conditions. The reaction was carried
out in a flow-type tubular reactor. The residence time was fixed at 40 min. When the molar ratio of methanol to palm oil was
set to 20:1 at 325 °C and 35 MPa, the optimum molar ratio of methanol to co-solvent was found to be 20:1. Addition of HCFC-141b
increased FAME production even at the lower molar ratio of methanol to palm oil. In addition, a similar FAME content was obtained
under the milder conditions (5 MPa lower pressure) compared with conditions without co-solvent at higher pressure. The role
of HCFC-141b in the transesterification reaction under supercritical conditions was investigated. 相似文献