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161.
Dr. Panos Datskos Dr. David A. Cullen Dr. Jaswinder Sharma 《Angewandte Chemie (International ed. in English)》2015,54(31):9011-9015
The synthesis of complex and hybrid oxide microstructures is of fundamental interest and practical applications. However, the design and synthesis of such structures is a challenging task. A solution‐phase process to synthesize complex silica and silica–titania hybrid microstructures was developed by exploiting the emulsion‐droplet‐based step‐by‐step growth featuring shape control. The strategy is robust and can be extended to the preparation of complex hybrid structures consisting of two or more materials, with each having its own shape. 相似文献
162.
Mahdi Muhammad Moosa Dr. Allan Chris M. Ferreon Prof. Dr. Ashok A. Deniz 《Chemphyschem》2015,16(1):90-94
Intrinsically disordered proteins (IDPs) are involved in diverse cellular functions. Many IDPs can interact with multiple binding partners, resulting in their folding into alternative ligand‐specific functional structures. For such multi‐structural IDPs, a key question is whether these multiple structures are fully encoded in the protein sequence, as is the case in many globular proteins. To answer this question, here we employed a combination of single‐molecule and ensemble techniques to compare ligand‐induced and osmolyte‐forced folding of α‐synuclein. Our results reveal context‐dependent modulation of the protein′s folding landscape, suggesting that the codes for the protein′s native folds are partially encoded in its primary sequence, and are completed only upon interaction with binding partners. Our findings suggest a critical role for cellular interactions in expanding the repertoire of folds and functions available to disordered proteins. 相似文献
163.
Nishit Goradia Christoph Wiedemann Dr. Christian Herbst Dr. Matthias Görlach Prof. Dr. Stefan H. Heinemann Dr. Oliver Ohlenschläger Dr. Ramadurai Ramachandran 《Chemphyschem》2015,16(4):739-746
An efficient approach to NMR assignments in intrinsically disordered proteins is presented, making use of the good dispersion of cross peaks observed in [15N,13C′]‐ and [13C′,1HN]‐correlation spectra. The method involves the simultaneous collection of {3D (H)NCO(CAN)H and 3D (HACA)CON(CA)HA} spectra for backbone assignments via sequential HN and Hα correlations and {3D (H)NCO(CACS)HS and 3D (HS)CS(CA)CO(N)H} spectra for side‐chain 1H and 13C assignments, employing sequential 1H data acquisitions with direct detection of both the amide and aliphatic protons. The efficacy of the approach for obtaining resonance assignments with complete backbone and side‐chain chemical shifts is demonstrated experimentally for the 61‐residue [13C,15N]‐labelled peptide of a voltage‐gated potassium channel protein of the Kv1.4 channel subunit. The general applicability of the approach for the characterisation of moderately sized globular proteins is also demonstrated. 相似文献
164.
Dissecting Cooperative Communications in a Protein with a High‐Throughput Single‐Molecule Scalpel
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Miscued communication often leads to misfolding and aggregation of the proteins involved in many diseases. Owing to the ensemble average property of conventional techniques, detailed communication diagrams are difficult to obtain. Mechanical unfolding affords an unprecedented perspective on cooperative transitions by observing a protein along a trajectory defined by two mutated cysteine residues. Nevertheless, this approach requires tedious sample preparation at the risk of altering native protein conformations. To address these issues, we applied click chemistry to tether a protein to the two dsDNA handles through primary amines in lysine residues as well as at the N terminus. As a proof of concept, we used laser tweezers to mechanically unfold and refold calmodulin along 36 trajectories, maximally allowed by this strategy in a single batch of protein preparation. Without a priori knowledge of the particular residues to which the double‐stranded DNA handles attach, we used hierarchical cluster analysis to identify 20 major trajectories, according to the size and the pattern of unfolding transitions. We dissected the cooperativity into all‐or‐none and partially cooperative events, which represent strong and weak high‐order interactions in proteins, respectively. Although the overall cooperativity is higher within the N or C lobe than that between the lobes, the all‐or‐none cooperativity is anisotropic among different the unfolding trajectories and becomes relatively more predominant when the size of the protein segments increases. The average cooperativity for all‐or‐none transitions falls within the expected range observed by ensemble techniques, which supports the hypothesis that unfolding of a free protein can be reconstituted from individual trajectories. 相似文献
165.
Molecular simulations can be used to study disordered polypeptide systems and to generate hypotheses on the underlying structural and thermodynamic mechanisms that govern their function. As the number of disordered protein systems investigated with simulations increase, it is important to understand how particular force fields affect the structural properties of disordered polypeptides in solution. To this end, we performed a comparative structural analysis of Gly3 and Gly10 in aqueous solution from all atom, microsecond molecular dynamics (MD) simulations using the CHARMM 27 (C27), CHARMM 36 (C36), and Amber ff12SB force fields. For each force field, Gly3 and Gly10 were simulated for at least 300 ns and 1 μs, respectively. Simulating oligoglycines of two different lengths allows us to evaluate how force field effects depend on polypeptide length. Using a variety of structural metrics (e.g., end‐to‐end distance, radius of gyration, dihedral angle distributions), we characterize the distribution of oligoglycine conformers for each force field and show that each sample conformation space differently, yielding considerably different structural tendencies of the same oligoglycine model in solution. Notably, we find that C36 samples more extended oligoglycine structures than both C27 and ff12SB. © 2015 Wiley Periodicals, Inc. 相似文献
166.
Using cheap n‐butylamine as template, ZSM‐5 zeolites have been successfully synthesized and coated on monolithic interconnected macroporous Al2O3 by the secondary growth method. The use of cheap n‐butylamine could significantly reduce the synthesis cost. Hierarchical monolithic ZSM‐5 zeolites were prepared from synthetic mixtures with different H2O/Na2O or SiO2/Al2O3 ratio. The synthesized samples were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR) and N2 adsorption‐desorption. The results show that the hierarchical monolithic zeolites were obtained with cheap n‐butylamine template as template. During the hydrothermal reaction process, the morphology of the micrometer‐sized support was well maintained. The irregular crystals were formed in a wide range of the H2O/Na2O or SiO2/Al2O3 ratio of synthetic mixtures and coated on monolithic Al2O3. The relative crystallinity of the zeolites was highest at H2O/Na2O=250 or SiO2/Al2O3=160. This type of composites exhibited hierarchical porous structures and relatively high specific surface areas. 相似文献
167.
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169.
In Bayesian analysis, the Markov Chain Monte Carlo (MCMC)
algorithm is an efficient and simple method to compute posteriors. However, the
chain may appear to converge while the posterior is improper, which will leads
to incorrect statistical inferences. In this paper, we focus on the necessary and
sufficient conditions for which improper hierarchical priors can yield proper
posteriors in a multivariate linear model. In addition, we carry out a simulation
study to illustrate the theoretical results, in which the Gibbs sampling and
Metropolis-Hasting sampling are employed to generate the posteriors. 相似文献
170.
Dr. Qiang Gao Chuan-Qi Huang Yi-Ming Ju Dr. Min-Rui Gao Dr. Jian-Wei Liu Duo An Dr. Chun-Hua Cui Dr. Ya-Rong Zheng Prof. Dr. Wei-Xue Li Prof. Dr. Shu-Hong Yu 《Angewandte Chemie (International ed. in English)》2017,56(27):7769-7773
Cobalt-based nanomaterials have been intensively explored as promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. Herein, we report phase-selective syntheses of novel hierarchical CoTe2 and CoTe nanofleeces for efficient OER catalysts. The CoTe2 nanofleeces exhibited excellent electrocatalytic activity and stablity for OER in alkaline media. The CoTe2 catalyst exhibited superior OER activity compared to the CoTe catalyst, which is comparable to the state-of-the-art RuO2 catalyst. Density functional theory calculations showed that the binding strength and lateral interaction of the reaction intermediates on CoTe2 and CoTe are essential for determining the overpotential required under different conditions. This study provides valuable insights for the rational design of noble-metal-free OER catalysts with high performance and low cost by use of Co-based chalcogenides. 相似文献