排序方式: 共有54条查询结果,搜索用时 15 毫秒
1.
Dr. Oleksii Zozulia Dr. Liam R. Marshall Dr. Inhye Kim Eric M. Kohn Prof. Dr. Ivan V. Korendovych 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5388-5392
The self-assembly of short peptides gives rise to versatile nanomaterials capable of promoting efficient catalysis. We have shown that short, seven-residue peptides bind hemin to produce functional catalytic materials which display highly efficient peroxidation activity, reaching a catalytic efficiency of 3×105 m −1 s−1. Self-assembly is essential for catalysis as non-assembling controls show no activity. We have also observed peroxidase activity even in the absence of hemin, suggesting the potential to alter redox properties of substrates upon association with the assemblies. These results demonstrate the practical utility of self-assembled peptides in various catalytic applications and further support the evolutionary link between amyloids and modern-day enzymes. 相似文献
2.
3.
Dr. Sergiy V. Zasukha Prof. Dr. Vadim M. Timoshenko Prof. Dr. Andrey A. Tolmachev Valentyna O. Pivnytska Oleksii Gavrylenko Dr. Serhii Zhersh Prof. Dr. Yuriy Shermolovich Dr. Oleksandr O. Grygorenko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(28):6928-6940
Two novel solid reagents—1-sulfonimidoyl- and 1-sulfamimidoyl-3-methylimidazolium derivatives—for the synthesis of sulfonimidamides and imidosulfuric diamides, respectively, were developed. It is shown that these reagents are very effective in substitution reactions with various N- and O-nucleophiles; therefore, they significantly extend the accessibility to the chemical space covered by organosulfur(VI) compounds with S=N bonds. In addition, previously unknown imidosulfuric diamides with free imino nitrogen groups were prepared, and their physical and chemical properties were characterized (including molecular geometry, pKa, Log P, microsomal stability, and reactivity towards typical electrophiles). Similar to other organosulfur(VI) derivatives with S=N bonds, these compounds can be considered as promising bioisosteres of amides, ureas, or sulfonamides. 相似文献
4.
5.
Maksym S. Kazunin Oleksii Yu. Voskoboynik Inna S. Nosulenko Galina G. Berest Sergiy V. Kholodniak Boris O. Pryymenko Sergiy I. Kovalenko 《Journal of heterocyclic chemistry》2020,57(1):268-280
The synthesis of 6-(2-hydroxy-2-aryl (heteryl)ethyl)-1-methylpteridine-2,4,7(1H,3H,8H)-triones by the reduction of the corresponding ketones and the peculiarities of conversion of the synthesized alcohols to (E)-1-methyl-6-(2-aryl (heteryl)ethenyl)pteridine-2,4,7(1H,3H,8H)-triones was reported. The mechanism of monomolecular elimination that occurred in the presence of hydrogen halides was discussed, namely, the competitive formation of an energy-efficient conjugated system by deprotonation of a stable benzyl-type carbocation. Alternative synthesis methods of pteridine-2,4,7(1H,3H,8H)-triones were developed. Abovementioned approach involved [4+2]-cyclocondensation of 1-methyl-5,6-diaminouracil to 2-oxo-4-R-but-3-enoic acids and Knoevenagel condensation of 1,6-dimethylpteridine-2,4,7(1H,3H,8H)-trione with aromatic aldehydes. The antiradical, antimicrobial, and antifungal activities were studied for the synthesized compounds. 相似文献
6.
Oleksii Zozulia Ivan V. Korendovych 《Angewandte Chemie (International ed. in English)》2020,59(21):8108-8112
The self‐assembly of short peptides gives rise to versatile nanoassemblies capable of promoting efficient catalysis. We have semi‐rationally designed a series of seven‐residue peptides that form hemin‐binding catalytic amyloids to facilitate enantioselective cyclopropanation with efficiencies that rival those of engineered hemin proteins. These results demonstrate that: 1) Catalytic amyloids can bind complex metallocofactors to promote practically important multisubstrate transformations. 2) Even essentially flat surfaces of amyloid assemblies can impart a substantial degree of enantioselectivity without the need for extensive optimization. 3) The ease of peptide preparation allows for straightforward incorporation of unnatural amino acids and the preparation of peptides made from d ‐amino acids with complete reversal of enantioselectivity. 相似文献
7.
Kovalenko OO Brusylovets OA Kinzhybalo V Lis T Brusilovets AI 《Dalton transactions (Cambridge, England : 2003)》2011,40(18):4814-4817
The low-coordinate phosphorus compounds (Me(3)Si)(2)N-P=NSiMe(3), (Me(3)Si)(2)N-P(=S)=N(t)Bu and (Me(3)Si)(2)N-P(=NSiMe(3))(2) react with ((i)PrO)(3)M≡M(O(i)Pr)(3) (M = Mo, W) to form four- and five-membered metallacycles with intact endocyclic or exocyclic M≡M triple bonds. The first four-membered planar metallacycles, containing an M≡M triple bond were obtained in reaction with (Me(3)Si)(2)N-P=NSiMe(3). 相似文献
8.
Corrugated pipes are commonly used because of their local rigidity combined with global flexibility. The flow through such a pipe can induce strong whistling tones, which is an environmental nuisance and can be a threat to the mechanical integrity of the system. This paper considers the use of a composite pipe: a shorter corrugated pipe segment embedded between smooth pipe segments. Such a pipe retains some flexibility, while the acoustical damping in the smooth pipe reduces whistling tones. Whistling is the result of coherent vortex shedding at the cavities in the wall. This vortex shedding is synchronized by longitudinal acoustic waves traveling along the pipe. The acoustic waves trigger the vortex shedding, which reinforces the acoustic field for a critical range of the Strouhal number values. A linear theory for plane wave propagation and the sound production is proposed, which allows a prediction of the Mach number at the threshold of whistling in such pipes. A semi-empirical approach is chosen to determine the sound source in this model. This source corresponds to a fluctuating force acting on the fluid as a consequence of the vortex shedding. The functional form of the Strouhal number dependency of the dimensionless sound source amplitude is based on numerical simulations. The magnitude of the source and the Strouhal number range in which it can drive whistling are determined by matching the model to results for a specific corrugated pipe segment length. This semi-empirical source model is then applied to composite pipes with different corrugated segment lengths. In addition, the effect of inlet acoustical convective losses due to flow separation is considered. The Mach number at the threshold of whistling is predicted within a factor 2. 相似文献
9.
This paper presents a theoretical moment-curvature relationship for rectangular plates having bitrapezoidal cross sections. It is shown that, for certain values of the cross-section camber and edge thickness, the plates exhibit a bending instability for some values of longitudinal curvature. Experimental results show good agreement between theory and experiment. 相似文献
10.
Agata Semeniuk Justyna Kalinowska-Tluscik Wojciech Nitek Barbara J. Oleksyn 《Journal of chemical crystallography》2008,38(5):333-338
Abstract The crystal structure of hydroxychloroquine sulfate (OHClQ) was determined in order to compare its conformation and intermolecular
interactions to those in the crystalline chloroquine phosphate (ClQP) and quinine salicylate (QSal) monohydrate. The crystals
of OHClQ are monoclinic with the space group P21/c and unit-cell dimensions: a = 10.4966(1) ?, b = 8.8056(1) ?, c = 21.8603(3) ?, β = 101.074(1)°. The quinoline antimalarial drugs may interact with their putative receptors by formation
of characteristic hydrogen-bonded rings. The protonated nitrogen atoms and/or hydroxyl groups of the drug cation are proton
donors, while the oxygen atoms of anions are proton acceptors. Water molecules may intermediate in these interactions.
Graphical Abstract Hydroxychloroquine sulfate is a drug used in the treatment of malaria and rheumatic diseases. The X-ray structure analysis
shows an important role of intermolecular hydrogen bonds in the crystal architecture. Comparison with chloroquine phosphate
and quinine salicylate indicates that the organization of the drug cations is determined by the anions.
相似文献