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Beat Schmid 《Probability Theory and Related Fields》1972,23(4):255-259
Ohne ZusammenfassungWie der Autor nachtrÄglich am 7th Mathematical Progr. Symposion in Den Haag von Herrn Elmaghraby erfahren hat, ist das in dieser Arbeit angegebene Lemma für Restriktionen mit nichtnegativen Koeffizienten schon im letzten Jahrhundert von Mathew bewiesen worden. 相似文献
33.
Duilio Arigoni David E. Cane Beat Müller Christoph Tamm 《Helvetica chimica acta》1973,56(8):2946-2949
In the course of the biosynthesis of verrucarol ( 3 ) from farnesyl pyrophosphate in Myrothecium roridum, strain S 1135, a hydride shift occurs from the central double bond of the precursor to C(2) of the product. 相似文献
34.
Structure Elucidation of a Dimethylfulvene-trimer. Evidence for a [6+ 4]-Dimerization of 6, 6-Dimethylfulvene Thermal reaction of pure 6, 6-dimethylfulvene ( 1c ) at 60° gives an oligomeric mixture consisting mainly of fulvene-trimers. The structure of the main product 3c is partially elucidated by 1H-NMR. investigations at 400 MHz and definitely confirmed by X-ray analysis. The formation of 3c is explained in terms of a [6+4] dimerization, followed by a 1, 5-proton-shift and a final Diels-Alder reaction. 相似文献
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Magnetic-resonance force microscopy is combined with cross-polarization and spin-decoupling NMR techniques to obtain double-resonance NMR signals of micrometer-scaled objects. The effective one-dimensional spatial resolution obtained in our experiments performed on a KPF6 single crystal sample is approximately 0.5 microm. The spectral linewidth of 900 Hz is sample limited. The described double-resonance techniques can introduce new chemical specificity to the magnetic-force sensor. 相似文献
37.
Albert A. Smith Matthias Ernst Sereina Riniker Beat H. Meier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9483-9488
Nuclear magnetic resonance (NMR) relaxation data and molecular dynamics (MD) simulations are combined to characterize the dynamics of the fungal prion HET‐s(218‐289) in its amyloid form. NMR data is analyzed with the dynamics detector method, which yields timescale‐specific information. An analogous analysis is performed on MD trajectories. Because specific MD predictions can be verified as agreeing with the NMR data, MD was used for further interpretation of NMR results: for the different timescales, cross‐correlation coefficients were derived to quantify the correlation of the motion between different residues. Short timescales are the result of very local motions, while longer timescales are found for longer‐range correlated motion. Similar trends on ns‐ and μs‐timescales suggest that μs motion in fibrils is the result of motion correlated over many fibril layers. 相似文献
38.
We investigate the creation of highly entangled ground states in a system of three exchange-coupled qubits arranged in a ring geometry. Suitable magnetic field configurations yielding approximate Greenberger-Horne-Zeilinger and exact W ground states are identified. The entanglement in the system is studied at finite temperature in terms of the mixed-state tangle tau. By generalizing a conjugate gradient optimization algorithm originally developed to evaluate the entanglement of formation, we demonstrate that tau can be calculated efficiently and with high precision. We identify the parameter regime for which the equilibrium entanglement of the tripartite system reaches its maximum. 相似文献
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Monitoring ssDNA Binding to the DnaB Helicase from Helicobacter pylori by Solid‐State NMR Spectroscopy
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Dr. Thomas Wiegand Riccardo Cadalbert Dr. Carole Gardiennet Dr. Joanna Timmins Dr. Laurent Terradot Dr. Anja Böckmann Prof. Dr. Beat H. Meier 《Angewandte Chemie (International ed. in English)》2016,55(45):14164-14168
DnaB helicases are bacterial, ATP‐driven enzymes that unwind double‐stranded DNA during DNA replication. Herein, we study the sequential binding of the “non‐hydrolysable” ATP analogue AMP‐PNP and of single‐stranded (ss) DNA to the dodecameric DnaB helicase from Helicobacter pylori using solid‐state NMR. Phosphorus cross‐polarization experiments monitor the binding of AMP‐PNP and DNA to the helicase. 13C chemical‐shift perturbations (CSPs) are used to detect conformational changes in the protein upon binding. The helicase switches upon AMP‐PNP addition into a conformation apt for ssDNA binding, and AMP‐PNP is hydrolyzed and released upon binding of ssDNA. Our study sheds light on the conformational changes which are triggered by the interaction with AMP‐PNP and are needed for ssDNA binding of H. pylori DnaB in vitro. They also demonstrate the level of detail solid‐state NMR can provide for the characterization of protein–DNA interactions and the interplay with ATP or its analogues. 相似文献