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Dr. Ambika Bhagi-Damodaran Maximilian Kahle Yelu Shi Prof. Dr. Yong Zhang Prof. Dr. Pia Ädelroth Prof. Dr. Yi Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6722-6726
Heme-copper oxidase (HCO) is a class of respiratory enzymes that use a heme-copper center to catalyze O2 reduction to H2O. While heme reduction potential (E°′) of different HCO types has been found to vary >500 mV, its impact on HCO activity remains poorly understood. Here, we use a set of myoglobin-based functional HCO models to investigate the mechanism by which heme E°′ modulates oxidase activity. Rapid stopped-flow kinetic measurements show that increasing heme E°′ by ca. 210 mV results in increases in electron transfer (ET) rates by 30-fold, rate of O2 binding by 12-fold, O2 dissociation by 35-fold, while decreasing O2 affinity by 3-fold. Theoretical calculations reveal that E°′ modulation has significant implications on electronic charge of both heme iron and O2, resulting in increased O2 dissociation and reduced O2 affinity at high E°′ values. Overall, this work suggests that fine-tuning E°′ in HCOs and other heme enzymes can modulate their substrate affinity, ET rate and enzymatic activity. 相似文献
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Proton Affinities of Cationic Carbone Adducts [AC(PPh3)2]+ (A=Halogen,Hydrogen, Methyl) and Unusual Electronic Structures of the Cations and Dications [AC(H)(PPh3)2]2+ 下载免费PDF全文
Prof. Dr. Wolfgang Petz Dr. Istemi Kuzu Prof. Dr. Gernot Frenking Dr. Diego M. Andrada Prof. Dr. Bernhard Neumüller Maximilian Fritz Jörn E. Münzer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8536-8546
This work reports the syntheses and the first crystal structures of the cationic carbone adducts [FC(PPh3)2]+ and [BrC(PPh3)2]+ and the protonated dication [FC(H)(PPh3)2]2+, which are derived from the carbone C(PPh3)2. Quantum chemical calculations and bonding analyses were carried out for the series of cations [AC(PPh3)2]+ and dications [AC(H)(PPh3)2]2+, where A=H, Me, F, Cl, Br, I. The bonding analysis suggests that the cations are best described as phosphane complexes L→(CA)+←L (L=PPh3), which are related to the neutral borylene adducts L→(BA)←L (L=cyclic carbene; A=H, aryl) that were recently isolated. The carbone adducts [AC(PPh3)2]+ possess a π electron lone pair at carbon and they can easily be protonated to the dications [AC(H)(PPh3)2]2+. The calculations of the dications indicate that the molecules are best represented as complexes L→(CHA)2+←L (L=PPh3) where a carbene dication is stabilized by the ligands. The central carbon atom in the cations and even in the dications carries a negative partial charge, which is larger than the negative charge at fluorine. There is also the peculiar situation in which the carbon–fluorine bonds in [FC(PPh3)2]+ and [FC(H)(PPh3)2]2+ exhibit the expected polarity with the negative end at fluorine, but the carbon atom has a larger negative charge than fluorine. Given the similarity of carbodiphosphorane C(PPh3)2 and carbodicarbene C(NHC)2, we expect that analogous compounds [AC(NHC)2]+ and [AC(H)(NHC)2]2+ with similar features as [AC(PPh3)2]+ and [AC(H)(PPh3)2]2+ can be isolated. 相似文献
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Le Zhang Munnangi Anji Reddy Ping Gao Thomas Diemant R. Jürgen Behm Maximilian Fichtner 《Journal of Solid State Electrochemistry》2017,21(5):1243-1251
In this work, a solid-state fluoride ion battery based on a thin-film electrolyte with 10 μm thickness was built and tested. The electrochemical performance was examined using Bi or Cu metals as the active cathode materials and MgF2 as the active anode material, respectively. X-ray diffraction and X-ray photoelectron spectroscopy data showed that the charge transfer ions between the cathode and anode were fluoride ions. Initial discharge capacities of 66 and 76 mAh g?1 were obtained at 160 °C when Bi and Cu were used as cathodes, respectively. Furthermore, this type of fluoride ion battery was rechargeable, but the capacity faded during the subsequent cycles, similar to the bulk-type systems. 相似文献
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In electrical machines, sheet-layered lamination stacks play an important role for the mechanical behavior of the system. Especially the interlayer between individual sheets and their interaction have a severe influence on the structure. In the context of performance and computational effort, it is desirable to avoid a full FE simulation of a lamination stack with every single sheet. Therefore, homogenization techniques are presented to identify a transversely isotropic surrogate material model, while Zero-Thickness elements are utilized during this process to cover the interplay of single sheets. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
160.
Franziska Boneberg Angie Kirchner Prof. Dr. Thomas M. Klapötke Davin G. Piercey Maximilian J. Poller Jörg Stierstorfer 《化学:亚洲杂志》2013,8(1):148-159
In this work we report on the syntheses of energetic salts of cyanotetrazolate‐1‐ and ‐2‐oxides; this offers a unique ability to compare the effects of tetrazole 1‐ versus 2‐oxidation. 5‐Cyanotetrazolate‐2‐oxide can be synthesized by oxidation of the 5‐cyanotetrazolate anion with Oxone, while the corresponding 1‐oxide was synthesized by the rearrangement of azidoaminofurazan. Both chemical (multinuclear NMR, IR, and Raman spectroscopies, mass spectrometry, etc.) as well as explosive (impact, friction, and static sensitivities) properties are reported for these energetic salts. Calculated explosive performances using the EXPLO5 computer code are also reported. We furthermore detail the chemistry of these two anions, and their ability to form tetrazole‐carboxamides, dihydrotetrazines, and tetrazines. The ability to hydrolyze cyanotetrazole oxides to their amides was demonstrated by two copper complexes. Several crystal structures of these species are presented in addition to full chemical characterization. Finally, the unique 1,4,‐bis(2‐N‐oxidotetrazolate)‐1,2,4,5‐tetrazine anion was characterized as an energetic material as its ammonium salt. 相似文献