ISSN:1075-2617    

DOI:10.1002/psc.2669

年代:2014

数据来源: WILEY

摘要:

The self‐assembly of several classes of amphiphilic peptides is reviewed, and selected applications are discussed. We discuss recent work on the self‐assembly of lipopeptides, surfactant‐like peptides and amyloid peptides derived from the amyloid‐βpeptide. The influence of environmental variables such as pH and temperature on aggregate nanostructure is discussed. Enzyme‐induced remodelling due to peptide cleavage and nanostructure control through photocleavage or photo‐cross‐linking are also considered. Lastly, selected applications of amphiphilic peptides in biomedicine and materials science are outlined. © 2014 The Authors.Journal of Peptide Sciencepublished by European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.2633

年代:2014

数据来源: WILEY

摘要:

Nanotechnology is an expanding area of study with potentially pivotal applications in a discipline as medicine where new biomedical active molecules or strategies are continuously developing. One of the principal drawbacks for the application of new therapies is the difficulty to cross membranes that represent the main physiological barrier in our body and in all living cells. Membranes are selectively permeable and allow the selective internalization of substances; generally, they form a highly impermeable barrier to most polar and charged molecules, and represent an obstacle for drug delivery, limiting absorption to specific routes and mechanisms. Viruses provide attracting suggestions for the development of targeted drug carriers as they have evolved naturally to deliver their genomes to host cells with high fidelity.A detailed understanding of virus structure and their mechanisms of entry into mammalian cells will facilitate the development and analysis of virus‐based materials for medical applications. Copyright © 2014 European Peptide Society and John Wiley&Sons, L

ISSN:1075-2617    

DOI:10.1002/psc.2649

年代:2014

数据来源: WILEY

摘要:

AbstractFunctional structures and materials are formed spontaneously in nature through the process of self‐assembly. Mimicking this processin vitrowill lead to the formation of new substances that would impact many areas including energy production and storage, biomaterials and implants, and drug delivery. The considerable structural diversity of peptides makes them appealing building blocks for self‐assemblyin vitro. This paper describes the self‐assembly of three aromatic dipeptides containing an azide moiety: H‐Phe(4‐azido)‐Phe(4‐azido)‐OH, H‐Phe(4‐azido)‐Phe‐OH, and H‐Phe‐Phe(4‐azido)‐OH. The peptide H‐Phe(4‐azido)‐Phe(4‐azido)‐OH self‐assembled into porous spherical structures, whereas the peptides H‐Phe(4‐azido)‐Phe‐OH and H‐Phe‐Phe(4‐azido)‐OH did not form any ordered structures under the examined experimental conditions. The azido group of the peptide can serve as a photo cross‐linking agent upon irradiation with UV light. To examine the effect of this group and its activity on the self‐assembled structures, we irradiated the assemblies in solution for different time periods. Using electron microscopy, we determined that the porous spherical assemblies formed by the peptide H‐Phe(4‐azido)‐Phe(4‐azido)‐OH underwent a structural change upon irradiation. In addition, using FT‐IR, we detected the chemical change of the peptide azido group. Moreover, using indentation experiments with atomic force microscopy, we showed that the Young's modulus of the spherical assemblies increased after 20 min of irradiation with UV light. Overall, irradiating the solution of the peptide assemblies containing the azido group resulted in a change both in the morphology and mechanical properties of the peptide‐based structures. These ordered assemblies or their peptide monomer building blocks can potentially be incorporated into other peptide assemblies to generate stiffer and more stabl

ISSN:1075-2617    

DOI:10.1002/psc.2646

年代:2014

数据来源: WILEY

摘要:

ABSTRACTThermally induced phase transformation in bioorganic nanotubes, which self‐assembled from two ultrashort dipeptides of different origin, aromatic diphenylalanine (FF) and aliphatic dileucine (LL), is studied. In both FF and LL nanotubes, irreversible phase transformation found at 120–180 °C is governed by linear‐to‐cyclic dipeptide molecular modification followed by formation of extended β‐sheet structure. As a result of this process, native open‐end FF and LL nanotubes are transformed into ultrathin nanofibrils. Found deep reconstructions at all levels from macroscopic (morphology) and structural space symmetry to molecular give rise to new optical properties in both aromatic FF and aliphatic LL nanofibrils and generation of blue photoluminescence (PL) emission. It is shown that observed blue PL peak is similar in these supramolecular nanofibrillar structures and is excited by the network of non‐covalent hydrogen bonds that link newly thermally induced neighboring cyclic dipeptide strands to final extended β‐sheet structure of amyloid‐like nanofibrils. The observed blue PL peak in short dipeptide nanofibrils is similar to the blue PL peak that was recently found in amyloid fibrils and can be considered as the optical signature of β‐sheet structures. Nanotubular structures were characterized by environmental scanning electron microscope, ToF‐secondary ion mass spectroscopy, CD and fluorescence spectroscopy. Copyright © 2014 European Peptide Soci

ISSN:1075-2617    

DOI:10.1002/psc.2661

年代:2014

数据来源: WILEY

摘要:

Interactions between peptides are relevant from a biomedical point of view, in particular for the role played by their aggregates in different important pathologies, and also because peptide aggregates represent promising scaffolds for innovative materials.In the present article, the aggregation properties of the homo‐peptides formed byα‐aminoisobutyric acid (U) residues are discussed. The peptides investigated have chain lengths between six and 15 residues and comprise benzyl and naphthyl groups at the N‐ and C‐termini, respectively. Spectroscopic experiments and molecular dynamics simulations show that the shortest homo‐peptide, constituted by six U, does not exhibit any tendency to aggregate under the conditions examined. On the other hand, the homologous peptide with 15 U forms very stable and compact aggregates in 70/30(v/v)methanol/water solution. Atomic force microscopy images indicate that these aggregates promote formation of long fibrils once they are deposited on a mica surface. The aggregation phenomenon is mainly due to hydrophobic interactions occurring between very stable helical structures, and the aromatic groups in the peptides seem to play a minor role. Copyright © 2014 European Peptide Society and John Wile

ISSN:1075-2617    

DOI:10.1002/psc.2648

年代:2014

数据来源: WILEY

摘要:

In the absence of efficient crystallization methods, the molecular structures of fibrous assemblies have so far remained rather elusive. In this paper, we present a rational method to crystallize the lanreotide octapeptide by modification of a residue involved in a close contact.Indeed, we show that it is possible to modify the curvature of the lanreotide nanotubes and hence their diameter. This fine tuning leads to crystallization because the radius of curvature of the initially bidimensional peptide wall can be increased up to a point where the wall is essentially flat and a crystal is allowed to grow along a third dimension. By comparing X‐ray diffraction data and Fourier transform Raman spectra, we show that the nanotubes and the crystals share similar cell parameters and molecular conformations, proving that there is indeed a structural continuum between these two morphologies. These results illustrate a novel approach to crystallization and represent the first step towards the acquisition of an Å‐resolution structure of the lanreotide nanotubesβ‐sheet assembly. Copyright © 2014 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.2647

年代:2014

数据来源: WILEY

摘要:

Bicelles are model membrane systems that can be macroscopically oriented in a magnetic field at physiological temperature. The macroscopic orientation of bicelles allows to detect, by means of magnetic resonance spectroscopies, small changes in the order of the bilayer caused by solutes interacting with the membrane. These changes would be hardly detectable in isotropic systems such as vesicles or micelles. The aim of this work is to show that bicelles represent a convenient tool to investigate the behavior of antimicrobial peptides (AMPs) interacting with membranes, using electron paramagnetic resonance (EPR) spectroscopy. We performed the EPR experiments on spin‐labeled bicelles using various AMPs of different length, charge, and amphipathicity: alamethicin, trichogin GA IV, magainin 2, HP(2–20), and HPA3. We evaluated the changes in the order parameter of the spin‐labeled lipids as a function of the peptide‐to‐lipid ratio. We show that bicelles labeled at position 5 of the lipid chains are very sensitive to the perturbation induced by the AMPs even at low peptide concentrations. Our study indicates that peptides that are known to disrupt the membrane by different mechanisms (i.e., alamethicin vs magainin 2) show very distinct trends of the order parameter as a function of peptide concentration. Therefore, spin‐labeled bicelles proved to be a good system to evaluate the membrane disruption mechanism of new AMPs. Copyright © 2014 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.2645

年代:2014

数据来源: WILEY

摘要:

Peptides confer interesting properties to materials, supramolecular assemblies and to lipid membranes and are used in analytical devices or within delivery vehicles. Their relative ease of production combined with a high degree of versatility make them attractive candidates to design new such products. Here, we review and demonstrate how CD‐ and solid‐state NMR spectroscopic approaches can be used to follow the reconstitution of peptides into membranes and to describe some of their fundamental characteristics. Whereas CD spectroscopy is used to monitor secondary structure in different solvent systems and thereby aggregation properties of the highly hydrophobic domain of p24, a protein involved in vesicle trafficking, solid‐state NMR spectroscopy was used to deduce structural information and the membrane topology of a variety of peptide sequences found in nature or designed.15N chemical shift solid‐state NMR spectroscopy indicates that the hydrophobic domain of p24 as well as a designed sequence of 19 hydrophobic amino acid residues adopt transmembrane alignments in phosphatidylcholine membranes. In contrast, the amphipathic antimicrobial peptide magainin 2 and the designed sequence LK15 align parallel to the bilayer surface. Additional angular information is obtained from deuterium solid‐state NMR spectra of peptide sites labelled with2H3‐alanine, whereas31P and2H solid‐state NMR spectra of the lipids furnish valuable information on the macroscopic order and phase properties of the lipid matrix. Using these approaches, peptides and reconstitution protocols can be elaborated in a rational manner, and the analysis of a great number of peptide sequences is reviewed. Finally, a number of polypeptides with membrane topologies that are sensitive to a variety of environmental conditions such as pH, lipid composition and peptide‐to‐lipid ratio will be presented. Copyright © 2014 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/psc.2656

年代:2014

数据来源: WILEY

摘要:

The roughness and thickness of films formed by hybrid conjugates prepared by coupling poly(3,4‐ethylenedioxythiophene) and synthetic amino acids bearing a 3,4‐ethylenedioxythiophene group in the side chain have been significantly increased using a new synthetic approach. This procedure also provoked a more effective incorporation of the amino acid at the end of the polymer chains, as has been reflected by the electronic and electrochemical properties. Although the surface polarity of all these materials is similar to that of formamide, the hydrophilicity of the conjugates is higher than that of the conducting polymer. The surface energy of all the investigated systems is dominated by the dispersive component, even though the role played by the polar contribution is more important for the conjugates than for the conducting polymer. On the other hand, all the prepared materials behave as bioactive matrices. The electrochemical response of the conjugates coated with cells reflects the electro‐compatibility of these two‐component substrates. Thus, the ability to exchange charge reversibly of all conjugates increases considerably when they are coated with cellular monolayers, which has attributed to favorable interactions at the interface formed by the conjugate surface and the cellular monolayer. Copyright © 2014 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.2660

年代:2014

数据来源: WILEY