ISSN:1075-2617    

DOI:10.1002/psc.1348

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractSynthetic peptide monomers can self‐assemble into PNM such as nanotubes, nanospheres, hydrogels, etc. which represent a novel class of nanomaterials. Molecular recognition processes lead to the formation of supramolecular PNM ensembles containing crystalline building blocks. Such low‐dimensional highly ordered regions create a new physical situation and provide unique physical properties based on electron‐hole QC phenomena. In the case of asymmetrical crystalline structure, basic physical phenomena such as linear electro‐optic, piezoelectric, and nonlinear optical effects, described by tensors of the odd rank, should be explored. Some of the PNM crystalline structures permit the existence of spontaneous electrical polarization and observation of ferroelectricity. The PNM crystalline arrangement creates highly porous nanotubes when various residues are packed into structural network with specific wettability and electrochemical properties.We report in this review on a wide research of PNM intrinsic physical properties, their electronic and optical properties related to QC effect, unique SHG, piezoelectricity and ferroelectric spontaneous polarization observed in PNT due to their asymmetric structure. We also describe PNM wettability phenomenon based on their nanoporous structure and its influence on electrochemical properties in PNM.The new bottom‐up large scale technology of PNT physical vapor deposition and patterning combined with found physical effects at nanoscale, developed by us, opens the avenue for emerging nanotechnology applications of PNM in novel fields of nanophotonics, nanopiezotronics and energy storage devices. Copyright © 2010 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.1326

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractA family of His‐rich peptides has been shown to complex DNA and efficiently deliver these nucleic acids into eukaryotic cells. Therefore, these nanoscale complexes have potential applications in gene therapy. Here, we review a number of spectroscopic and biophysical investigations aimed at characterizing the supramolecular interactions of the peptides with the nucleic acids and when overcoming the membrane barriers of the cell. Furthermore, solid‐state NMR distance measurements for the first time reveal close interatomic distances between the amino acid side chains and the DNA phosphates within the transfection complex. A recent study indicates that the peptides are also potent transfectants of siRNAs and they could thereby be of potential interest for gene silencing therapies using these compounds. Copyright © 2010 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.1318

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractAmphiphilic helical peptides (Sar)m‐b‐(L‐Leu‐Aib)n(m= 22–25;n= 7, 8, 10) with a hydrophobic block as a right‐handed helix were synthesized and their mixtures with (Sar)25‐b‐(D‐Leu‐Aib)6containing the hydrophobic block as a left‐handed helix were examined in their molecular assembly formation. The single component (Sar)25‐b‐(D‐Leu‐Aib)6forms peptide nanotubes of 70 nm diameter and 200 nm length. The two‐component mixtures of (Sar)25‐b‐(D‐Leu‐Aib)6with (Sar)24‐b‐(L‐Leu‐Aib)7, (Sar)22‐b‐(L‐Leu‐Aib)8, and (Sar)25‐b‐(L‐Leu‐Aib)10yield peptide nanotubes of varying dimensions with 200 nm diameter and 400 nm length, 70 nm diameter and several micrometer length (maximum 30 µm), and 70 nm diameter and 100–600 nm length, respectively. The right‐handed and the left‐handed helix were thus found to be molecularly mixed due to the stereo‐complex formation and to generate nanotubes of different sizes. When the mismatch of the hydrophobic helical length between the two components was of four residues, the longest nanotube was generated. Correspondingly, the hydrophobic helical segments have to interdigitate with an anti‐parallel orientation at the hydrophobic core region of the na

ISSN:1075-2617    

DOI:10.1002/psc.1304

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractWe used the principles governing the selectivity and stability of coiled‐coil segments to design and experimentally test a set of four pairs of parallel coiled‐coil‐forming peptides composed of four heptad repeats. The design was based on maximizing the difference in stability between desired pairs and the most stable unwanted combinations usingN‐terminal helix initiator residues, favorable combinations of the electrostatic and hydrophobic interaction motifs and negative design motif based on burial of asparagine residues. Experimental analysis of all 36 pair combinations among the eight peptides was performed by circular dichroism (CD). On the basis of CD spectra, each peptide formed a high level of α‐helical structure exclusively in combination with its designed peptide partner which demonstrates the orthogonality of the designed peptide pair set. Copyright © 2010 European Peptide Society and John Wile

ISSN:1075-2617    

DOI:10.1002/psc.1331

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractAmphiphilic β‐sheet nanotapes based on the self‐assembly of 9mer and 7merde novodesigned β‐strand peptides were studied in the dilute regime. The hydrophobic face of the tapes consisted predominantly of aliphatic (leucine) side chains, while the hydrophilic tape face contained polar side chains (glutamine, arginine and glutamic acid). Both peptides underwent a transition from a monomeric random coil to a self‐assembled β‐sheet tape upon increase of peptide concentration in aqueous solutions. P9‐6 exhibited lower critical concentration (c*) for self‐assembly and thus higher propensity for self‐assembly in water, compared to the shorter P7‐6. At neutral pH where there was little net charge per peptide, self‐assembly was favoured compared to low pH in which there was a net + 1 charge per peptide; the net charge decreased overall intermolecular attraction, manifested as an increase in c* for self‐assembly in low compared to neutral pH aqueous solutions. Propensity for self‐assembly and β‐sheet formation was found to be greatly enhanced in a polar organic solvent (methanol) compared to water. These studies combined with future more extensive comparative studies between amphiphilic tapes based on aliphatic amino acid residues and amphiphilic tapes based on aromatic residues will throw more light on the relative importance of hydrophobicversusaromatic interactions for the stabilisation of peptide assemblies. Systematic studies of this kind may also allow us to throw light on the fundamental principles that drive peptide self‐assembly and β‐sheet formation; they may also lead to a set of refined criteria for the effective design of peptides with prescribed combination of properties appropriate for specific applications. Copyright © 2010 European Pepti

ISSN:1075-2617    

DOI:10.1002/psc.1335

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractAβ16–22(Ac‐KLVFFAE‐NH2) is one of the shortest amyloid fibril‐forming sequences identified in β‐amyloid peptide. At neutral pH, the peptide forms fibrils in the concentration range of 0.2–2.0 mMafter ≥ 10 days of incubation. Structures of the fibrils proposed based on solid‐state NMR and MD simulations studies suggest antiparallel arrangement of β‐strands and aromatic interactions between the Phe residues. In an effort to examine the role of aromatic interactions between two Phe residues in Aβ16–22, we have studied the self‐assembly of Aβ16–22(AβFF) and two of its variants, Ac‐KLVFWAE‐NH2(AβFW) and Ac‐KLVWFAE‐NH2(AβWF). The peptides were dissolved in methanol (MeOH) at a concentration of 1 mMand in water (AβFW and AβWF, 1 mM; AβFF, 330 µM). Peptide solutions (100 µM) were prepared in 50 mMsodium phosphate buffer at pH 7 by diluting from MeOH and water stock solutions. AβFW forms amyloid‐like fibrils immediately from MeOH, as indicated by atomic force microscopy. Dilution of AβFW into phosphate buffer from stock solution prepared in MeOH results in fibrils, but with different morphology and dimensions. The secondary structure potentiated by MeOH seems to be important for the self‐assembly of AβFW, as fibrils are not formed from water where the peptide is unordered. On the other hand, AβFF and AβWF do not form amyloid fibrils rapidly from any of the solvents used for dissolution. However, drying of AβWF from MeOH on mica surface gives rod‐like and fibrous structures. Our study indicates that positioning of the aromatic residues F and W has an important role to play in promoting self‐assembly of the Aβ16–22peptides. Copyr

ISSN:1075-2617    

DOI:10.1002/psc.1339

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractThe photocurrent generation properties of mono‐ and bi‐component peptide‐based self‐assembled monolayers (SAMs) immobilized on a gold surface were studied by electrochemical and spectroscopic techniques. The peptides investigated comprised almost exclusivelyCα‐tetrasubstituted α‐amino acids. These non‐coded residues, because of their unique conformational properties, forced the peptide backbone to attain a helical conformation, as confirmed by X‐ray crystal structure and CD determinations in solution. The peptide helical structure promoted the formation of a stable SAM on the gold surface, characterized by an electric macrodipole directed from theC(δ−) to theN(δ+) terminus, that remarkably affected the electron transfer (ET) process through the peptide chain. The peptides investigated were derivatized with chromophores strongly absorbing in the UV region to enhance the efficiency of the photocurrent generation (antenna effect). The influence of the nature of the peptide–gold interface on the ET process (junction effect) was analyzed by comparing the photocurrent generation process in peptide SAMs immobilized on a gold surface through AuS linkages with that in a bi‐component SAM embedding a photoactive peptide into the linked palisade formed by disulfide‐functionalized peptides. Copyright © 2010 European Peptide So

ISSN:1075-2617    

DOI:10.1002/psc.1329

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractThis work presents a computational strategy to model flexible molecules tethered to a metallic rigid surface. The method is based on a previously developed procedure for inert surfaces, in which peptide–surface interactions were not considered. This procedure is able to generate uncorrelated relaxed microstructures at the atomistic level of systems containing relatively high densities of peptides tethered to the surface. The reliability of the strategy has been tested by simulating CREKA (Cys‐Arg‐Glu‐Lys‐Ala), a short linear pentapeptide that recognizes clotted plasma proteins and selectively homes to tumors, covalently tethered to a gold surface, results being compared with those obtained when the surface was represented as inert. The results indicate that the whole conformational profile of CREKA presents some correlation with the chemical activity of the surface, even though the bioactive conformation was found as the most favored in all cases. Specifically, simulations reflect that consideration of the peptide‐surface interactions affect the geometrical orientation of the side chains, whereas the main chain conformation does not undergo significant modifications. Copyright © 2011 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.1321

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractCarbon nanotubes functionalized with cell adhesion peptides can be considered as novel, promising candidates for the development of advanced drug delivery systems or for designing new generation of self‐assembling nerve ‘bridges’. An important step toward the integration of these types of conjugates in living bodies is the assessment of their impact on the immune system. In this direction, an integrin‐derived peptide has been covalently conjugated to carbon nanotubes. Following intraperitoneal administration, peptide–carbon nanotubes do not trigger an anti‐peptide antibody production. Demonstration of the immune neutrality of peptide–carbon nanotubes reinforces their potential use as substrates for neuronal regenerationin vivo.Copyright © 2010 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.1290

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY