ISSN:1075-2617    

DOI:10.1002/psc.995

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractPeptide and protein self‐assembly is a well‐studied phenomenon in chemistry and biology, where nanoscopic building blocks exhibit rapid self‐association to reveal supramolecular aggregates of defined structural features. These superstructures are stabilized by hydrophobic interactions, hydrogen bonding and a host of other noncovalent interactions. Thus, amino acid side chains in the primary structure hold importance in dictating secondary structures and preference for particular conformational signatures in peptide aggregates. This report describes contrasting nanoscale morphologies in antamanide‐derived synthetic tetrapeptide mutants, which are composed by shuffling only two amino acids: phenylalanine and proline. Remarkable differences in ultrastructures in primary sequence‐shuffled tetrapeptides suggest dissimilar aggregational pathways due to context‐dependent location of proline and phenylalanine residues with respect to one another. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.955

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractIn this paper, the introduction of both a methionine residue and a nitrobenzyl derivative as a labile linker between the peptide part and the hydrophobic alkyl chain of a peptide amphiphile are presented. These modifications are shown not to inhibit the formation of structured assemblies that analogous peptide amphiphiles lacking the linkers are able to form. Moreover, the introduction of either labile linker allows removal of the peptide amphiphile's stabilizing hydrophobic moieties to initiate a controlled disassembly of fibre aggregates. This is achieved by either treatment with CNBr or UV irradiation, respectively. These disassembly mechanisms could be the starting point for methodology that allows further manipulation of self‐assembled peptide amphiphile architectures. Copyright © 2007 European Peptide Society and John Wiley&Sons, L

ISSN:1075-2617    

DOI:10.1002/psc.969

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractNanoparticles provide large surface areas and controlled surface functionality and structure, making them excellent scaffolds for peptide recognition. A family of nanoparticles has been fabricated by amino acid functionalization to afford tailored surfaces. These particles are complementary to a tetraaspartate peptide (TAP) featuring cofacial anionic functionality when in the α‐helical conformation. The functional groups present on these nanoparticle surfaces provide a tool to investigate the contribution of various noncovalent interactions at the nanoparticle–peptide interface. The ability of these particles to enforce the folding of the peptide into an α‐helix was explored, demonstrating high helicity induction with particles featuring dicationic amino acids such as lysine or histidine, and little or no helix stabilization with hydrophobic amino acid termini. Copyright © 2007 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.947

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractA series of surfactant peptides were created to evaluate the affinity of aromatic AAs for single‐walled carbon nanotubes in the absence of complications from peptide folding or self‐association. Each surfactant peptide has a lipidlike architecture, with two Lys residues at theC‐terminus as a hydrophilic head, five Val residues to form a hydrophobic tail, and the testing AA at theN‐terminus. Raman and CD spectroscopic studies reveal that the surfactant peptides have a large unordered structural component which is independent of peptide concentration, suggesting that the peptides undergo minimal association under experimental conditions, thus removing this interference from interpretation of the peptide/carbon nanotube interactions. A lack of peptide self‐association is also indicated by sedimentation equilibrium ultracentrifugation results. Optical spectroscopy of the peptide/carbon nanotube dispersions indicate that among the three aromatic AAs, tryptophan has the highest affinity for carbon nanotubes (both bundled and individual states) when incorporated into a surfactant peptide, while the Tyr‐containing peptide is more selective for individual carbon nanotubes. Phe has the lowest overall affinity for carbon nanotubes. Raman spectra of dispersions made with SPF, SPY and SPW display similar types of nanotubes dispersed, although differences in the relative nanotube populations are observed by optical spectroscopy. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.978

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractIt has been found that the self‐assembling peptide RADA 16‐I forms a β‐sheet structure and self‐assembles into nanofibers and scaffolds in favor of cell growth, hemostasis and tissue‐injury repair. But its biophysical and morphological properties, especially for its β‐sheet and self‐assembling properties in heat‐ and pH‐denatured conditions, remain largely unclear. In order to better understand and design nanobiomaterials, we studied the self‐assembly behaviors of RADA16‐I using CD and atomic force microscopy (AFM) measurements in various pH and heat‐denatured conditions. Here, we report that the peptide, when exposed to pH 1.0 and 4.0, was still able to assume a typical β‐sheet structure and self‐assemble into long nanofiber, although its β‐sheet content was dramatically decreased by 10% in a pH 1.0 solution. However, the peptide, when exposed to pH 13.0, drastically lost its β‐sheet structure and assembled into different small‐sized globular aggregates. Similarly, the peptide, when heat‐denatured from 25 to 70 °C, was still able to assume a typical β‐sheet structure with 46% content, but self‐assembled into small‐sized globular aggregates at much higher temperature. Titration experiments showed that the peptide RADA16‐I exists in three types of ionic species: acidic (fully protonated peptide), zwitterionic (electrically neutral peptide carrying partial positive and negative charges) and basic (fully deprotonated peptide) species, called ‘super ions’. The unordered structure and β‐turn of these ‘super ions’ via hydrogen or ionic bonds, and heat Brownian motion under the above denatured conditions would directly affect the stability of the β‐sheet and nanofibers. These results help us in the design of future nanobiomaterials, such as biosensors, based on β‐sheets and environmental changes. These results also help understand the pathogenesis of the β‐sheet‐mediated neuronal diseases such as Alzheimer's disease and the mechanism of hemost

ISSN:1075-2617    

DOI:10.1002/psc.988

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe blood‐brain barrier (BBB) regulates the passage of molecules between the bloodstream and the brain. Overcoming the difficulty of delivery drugs to specific areas of the brain is a major challenge. The BBB exerts a neuroprotective function as it hinders the delivery of diagnostic and therapeutic agents to the brain. Here, we provide an overview of the way in which peptides and nanotechnology are being exploited in tandem to address this problem. Peptides can be used as specialised coatings able to transport nanoparticles with specific properties, such as targeting. The nanoparticle can also carry a peptide drug. Furthermore, peptides can be used in less conventional approaches such as all‐peptide nanoparticles. In summary, the combined use of peptides and nanotechnology offers tremendous hope in the treatment of brain disorders. Copyright © 2007 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.983

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractMultivalent systems are well known for their enhanced ability to bind multivalent counterparts. This contribution addresses the question whether they can also behave as cooperative catalysts. Analyzing examples from our own laboratory we show that self‐assembled systems obtained by covering gold nanoclusters with thiol‐terminated amino acids and peptides behave indeed as cooperative catalysts. By comparing their activity profiles with those of discrete, multivalent systems we show what are minimal conditions to elicit cooperativity in multivalent systems. Reactions taken into considerations for our analysis are the hydrolyses of carboxylate‐ and phosphate esters. Copyright © 2008 European Peptide Society and John Wiley&Son

ISSN:1075-2617    

DOI:10.1002/psc.952

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe electroconductive properties and photocurrent generation capabilities of self‐assembled monolayers formed by conformationally‐constrained hexapeptides were studied by cyclic voltammetry, chronoamperometry, and photocurrent generation experiments. Lipoic acid was covalently linked to theN‐terminus of the peptides investigated to exploit the high affinity of the disulfide group to the gold substrates. Smart functionalization of the peptide scaffold with a redox‐active (TOAC) or a photosensitizer (Trp) amino acid allowed us to study the efficiency of peptide‐based self‐assembled monolayers to mediate electron transfer and photoinduced electron transfer processes on gold substrates. Interdigitated microelectrodes have shown higher film stability under photoexcitation, lower dark currents, and higher sensitivity with respect to standard gold electrodes. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.973

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractHelical peptides of 8mer, 16mer, and 24mer carrying a disulfide group at theN‐terminal and a ferrocene moiety at theC‐terminal were synthesized, and they were self‐assembled on gold by a sulfur–gold linkage. Infrared reflection–absorption spectroscopy and ellipsometry confirmed that they formed a monolayer with upright orientation. Cyclic voltammetry showed that the electron transfer from the ferrocene moiety to gold occurred even with the longest 24mer peptide. Chronoamperometry and electrochemical impedance spectroscopy were carried out to determine the standard electron transfer rate constants. It was found that the dependence of the electron‐transfer rates on the distance was significantly weak with the extension of the chain from 16mer to 24mer (decay constant β = 0.02–0.04). This dependence on distance cannot be explained by an electron tunneling mechanism even if increased hydrogen‐bonding cooperativity or molecular dynamics is considered. It is thus concluded that this long‐range electron transfer is operated by an electron hopping mechanism. Copyright © 2007 European Peptide Society and J

ISSN:1075-2617    

DOI:10.1002/psc.974

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY