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Jason P. Seeley Dr. Mircea Cotlet Aileen M. Eagleton Seiichiro Higashiya Prof. John T. Welch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(4):961-965
The fluorescence intensity of a C-terminal acceptor chromophore, N-(7-dimethylamino-4-methyl coumarin (DACM), increased proportionally with 280 nm irradiation of an increasing number of donor tryptophan residues located on a β-sheet forming polypeptide. The fluorescence intensity of the acceptor chromophore increased even as the length of the β-sheet edge approached 256 Å, well beyond the Förster radius for the tryptophan–acceptor chromophore pair. The folding of the peptides under investigation was verified by circular dichroism (CD) and deep UV resonance Raman experiments. Control experiments showed that the enhancement of DACM fluorescence occurred concomitantly with peptide folding. In other control experiments, the DACM fluorescence intensity of the solutions of tryptophan and DACM did not show any enhancement of DACM fluorescence with increasing tryptophan concentrations. Formation of fibrillar aggregates of the substrate peptides prepared for the fluorescence studies was undetectable by thioflavin T (ThT) fluorescence. 相似文献
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Andrey V. Lunchev Dr. Samuel A. Morris Dr. Rakesh Ganguly Prof. Andrew C. Grimsdale 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1819-1823
A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices. This synthetic method may be applicable to the synthesis of other azaacenes. 相似文献
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Manuel G. Ricardo Dayma Llanes Ludger A. Wessjohann Daniel G. Rivera 《Angewandte Chemie (International ed. in English)》2019,58(9):2700-2704
For the first time, the Petasis (borono‐Mannich) reaction is employed for the multicomponent labeling and stapling of peptides. The report includes the solid‐phase derivatization of peptides at the N‐terminus, Lys, and N?‐MeLys side‐chains by an on‐resin Petasis reaction with variation of the carbonyl and boronic acid components. Peptides were simultaneously functionalized with aryl/vinyl substituents bearing fluorescent/affinity tags and oxo components such as dihydroxyacetone, glyceraldehyde, glyoxylic acid, and aldoses, thus encompassing a powerful complexity‐generating approach without changing the charge of the peptides. The multicomponent stapling was conducted in solution by linking N?‐MeLys or Orn side‐chains, positioned at i, i+7 and i, i+4, with aryl tethers, while hydroxy carbonyl moieties were introduced as exocyclic fragments. The good efficiency and diversity oriented character of these methods show prospects for peptide drug discovery and chemical biology. 相似文献
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Prof. Miguel A. Sierra Prof. Luis Casarrubios Dr. María C. de la Torre 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(30):7232-7242
Overuse and misuse of antibacterial drugs has resulted in bacteria resistance and in an increase in mortality rates due to bacterial infections. Therefore, there is an imperative necessity of new antibacterial drugs. Bio-organometallic derivatives of antibacterial agents offer an opportunity to discover new active antibacterial drugs. These compounds are well-characterized products and, in several examples, their antibacterial activities have been studied. Both inhibition of the antibacterial activity and strong increase in the antibiotic activity of the parent drug have been found. The synthesis of the main classes of bio-organometallic derivatives of these drugs, as well as examples of the use of structure–activity relation (SAR) studies to increase the activity and to understand the mode of action of bio-organometallic antimicrobial peptides (BOAMPs) and platensimicyn bio-organometallic mimics is presented in this article. 相似文献
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Let be an abelian group. A finite multiset A over G is said to give a λ-fold factorization of G if there exists a multiset B over G such that each element of G occurs λ times in the multiset . In this article, restricting G to a cyclic group, we will provide sufficient conditions on a given multiset A under which the exact value or an upper bound of the minimum multiplicity λ of a factorization of G can be given by introducing a concept of ‘lcm-closure’. Furthermore, a couple of properties on a given factor A will be shown when A has a prime or prime power order (cardinality). A relation to multifold factorizations of the set of integers will be also glanced at a general perspective. 相似文献
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《大分子反应工程》2018,12(1)
A model is used to simulate batch copolymerization of caprolactam with hexamethylene diamine (HMD) and adipic acid (ADA) to produce nylon 6/6,6. Four different recipes are considered: a recipe containing caprolactam and an aqueous solution of HMD and ADA, a recipe containing caprolactam and dry HMD/ADA salt, and two recipes with a portion of the caprolactam replaced by nylon 6 cyclic dimer (CD). Consuming CD would be advantageous because CD is an undesirable side product from nylon 6 production. Simulation results lead to three important findings: (i) operation using dry salt rather than aqueous salt solution leads to higher degree of polymerization, (ii) substantial quantities of CD can be consumed to produce nylon 6/6,6 copolymer, and (iii) including water in the recipe is beneficial for achieving improved consumption of CD. The results of this study will be helpful in designing experiments aimed at improving industrial nylon 6/6,6 copolymerization processes. 相似文献
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Synthesis of poly(isopropenylphenoxy propylene carbonate) and its facile side‐chain functionalization into hydroxy‐polyurethanes 下载免费PDF全文
Chun Chieh Huang Ching Hsuan Lin Shenghong A. Dai 《Journal of polymer science. Part A, Polymer chemistry》2016,54(6):802-808
4‐Isopropenyl phenol ( 4‐IPP ) is a versatile dual functional intermediate that can be prepared readily from bisphenol‐A ( BPA ). Through etherification with epichlorohydrin to the phenolic group of 4‐IPP , it can be converted into 4‐isopropenyl phenyl glycidyl ether ( IPGE ). On further reaction with carbon dioxide in the presence of tetra‐n‐butyl ammonium bromide ( TBAB ) as the catalyst, IPGE was transformed into 4‐isopropenylphenoxy propylene carbonate ( IPPC ) in 90% yield. Cationic polymerization of IPPC with strong acid such as trifluoromethanesulfonic acid or boron trifluoride diethyl etherate as the catalyst at ?40 °C gave a linear poly(isopropenylphenoxy propylene carbonate), poly( IPPC ), with multicyclic carbonate groups substituted uniformly at the side‐chains of the polymer. The cyclic carbonate groups of poly( IPPC ) were further reacted with different aliphatic amines and diamines resulting in formation of polymers with hydroxy‐polyurethane on side‐chains. Syntheses, characterizations of poly( IPPC ) and its conversion into hydroxy‐polyurethane crosslinked polymers were presented. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 802–808 相似文献