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排序方式: 共有176条查询结果,搜索用时 15 毫秒
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This paper describes the design and synthesis of a family of pore-forming amphiphiles. Two of these amphiphiles, which are derived from cholic acid, lysine, and p-phenylenediamine, can produce pores in lipid bilayers as individual molecules. In sharp contrast, analogous amphiphiles that do not contain a rigid 1,4-phenylenediamide moiety favor the formation of dimer-based pores. Kinetic evidence in support of monomer- and dimer-based pores has been obtained from Na+ transport measurements across bilayers made from 1-palmitoyl-2-oleoyl-2-sn-glycero-3-phosphocholine (POPC). Structure-activity studies that have been carried out with pore-forming, dimer-based amphiphiles have also revealed a significant activity dependence on their overall compactness. The practical potential of pore-forming amphiphiles with controllable supramolecular properties is briefly discussed. 相似文献
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A di-walled molecular umbrella, composed of two choloyl groups, one spermidine moiety, and a 5-thiol(2-nitrobenzoyl) "handle", was covalently attached to a 16-mer oligonucleotide (S-dT16) through a disulfide bond. Incubation of this conjugate (1) with vesicles made from 1-palmitoyl-2-oleyol-sn-glycero-3-phosphocholine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (95/5, mol/mol) (200 nm diameter, extrusion) that contained entrapped glutathione (GSH) at 37 degrees C resulted in the liberation of the oligonucleotide and the umbrella-bound 5-mercapto(2-nitrobenzoyl) moiety (USH) via thiolate-disulfide interchange. The appearance of USH, together with the absence of leakage of entrapped GSH and a vesicular capture of the oligonucleotide that matches the extent of USH formation, provides compelling evidence for delivery of S-dT16 into the aqueous compartment of these vesicles. In a sense, the molecular umbrella functions like a "needle" in providing a pathway for the oligonucleotide (the "thread") to cross the membrane. 相似文献
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End-labeled free-solution electrophoresis of DNA 总被引:1,自引:0,他引:1
Meagher RJ Won JI McCormick LC Nedelcu S Bertrand MM Bertram JL Drouin G Barron AE Slater GW 《Electrophoresis》2005,26(2):331-350
DNA is a free-draining polymer. This subtle but "unfortunate" property of highly charged polyelectrolytes makes it impossible to separate nucleic acids by free-flow electrophoresis. This is why one must typically use a sieving matrix, such as a gel or an entangled polymer solution, in order to obtain some electrophoretic size separation. An alternative approach consists of breaking the charge to friction balance of free-draining DNA molecules. This can be achieved by labeling the DNA with a large, uncharged molecule (essentially a hydrodynamic parachute, which we also call a drag-tag) prior to electrophoresis; the resulting methodology is called end-labeled free-solution electrophoresis (ELFSE). In this article, we review the development of ELFSE over the last decade. In particular, we examine the theoretical concepts used to predict the ultimate performance of ELFSE for single-stranded (ssDNA) sequencing, the experimental results showing that ELFSE can indeed overcome the free-draining issue raised above, and the technological advances that are needed to speed the development of competitive ELFSE-based sequencing and separation technologies. Finally, we also review the reverse process, called free-solution conjugate electrophoresis (FSCE), wherein uncharged polymers of different sizes can be analyzed using a short DNA molecule as an electrophoretic engine. 相似文献
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Two ββ-dialkenyl- and ββ-dialkynyl-cyclopentanones 3 and 5 were synthesised using mixed methyl or t-butyl magnesiocuprates R2MeCu(MgX)2 and R2t-BuCu(MgX)2, where R is the alkenyl or alkynyl residue. Their thermal cyclisation leads to 2,8,9-functionalised [3.3.3)propellanones. 相似文献
7.
The mixing properties of exchangeable phospholipids, derived from 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine, with an exchangeable form of cholesterol have been used to monitor the transition from the liquid-disordered to the liquid-ordered phase in cholesterol-containing bilayers, made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-distearoyl-sn-glycero-3-phosphocholine, respectively. 相似文献
8.
Myriam Drouin Dr. Parvesh Wadhwani Dr. Stephan L. Grage Dr. Jochen Bürck Dr. Johannes Reichert Sébastien Tremblay Marie Sabine Mayer Christian Diel Alexander Staub Prof. Jean-François Paquin Prof. Dr. Anne S. Ulrich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(7):1511-1517
Solid-state 19F NMR is a powerful method to study the interactions of biologically active peptides with membranes. So far, in labelled peptides, the 19F-reporter group has always been installed on the side chain of an amino acid. Given the fact that monofluoroalkenes are non-hydrolyzable peptide bond mimics, we have synthesized a monofluoroalkene-based dipeptide isostere, Val-Ψ[(Z)-CF=CH]-Gly, and inserted it in the sequence of two well-studied antimicrobial peptides: PGLa and (KIGAKI)3 are representatives of an α-helix and a β-sheet. The conformations and biological activities of these labeled peptides were studied to assess the suitability of monofluoroalkenes for 19F NMR structure analysis. 相似文献
9.
Currently, feature annotation remains one of the main challenges in untargeted metabolomics. In this context, the information provided by high-resolution mass spectrometry (HRMS) in addition to accurate mass can improve the quality of metabolite annotation, and MS/MS fragmentation patterns are widely used. Accurate mass and a separation index, such as retention time or effective mobility (μeff), in chromatographic and electrophoretic approaches, respectively, must be used for unequivocal metabolite identification. The possibility of measuring collision cross-section (CCS) values by using ion mobility (IM) is becoming increasingly popular in metabolomic studies thanks to the new generation of IM mass spectrometers. Based on their similar separation mechanisms involving electric field and the size of the compounds, the complementarity of DTCCSN2 and μeff needs to be evaluated. In this study, a comparison of DTCCSN2 and μeff was achieved in the context of feature identification ability in untargeted metabolomics by capillary zone electrophoresis (CZE) coupled with HRMS. This study confirms the high correlation of DTCCSN2 with the mass of the studied metabolites as well as the orthogonality between accurate mass and μeff, making this combination particularly interesting for the identification of several endogenous metabolites. The use of IM-MS remains of great interest for facilitating the annotation of neutral metabolites present in the electroosmotic flow (EOF) that are poorly or not separated by CZE. 相似文献
10.
Thin film formation via the Layer‐by‐Layer method is now a well‐established and broadly used method in materials science. We have been keenly interested in exploiting this technique in the area of gas separations. Specifically, we have sought to create hyperthin (<100 nm) polyelectrolyte‐based membranes that have practical potential for the separation of CO2 from N2 (flue gas) and H2 from CO2 (syngas). In this personal account, we summarize recent studies that have been aimed at measuring the influence of a variety of factors that can affect the permeability and permeation selectivity of hyperthin polyelectrolyte multilayers (PEMs). 相似文献