摘要:

AbstractThe oxidative folding of small, cysteine‐rich peptides to selectively achieve the native disulfide bond connectivities is critical for discovery and structure‐function studies of many bioactive peptides. As the propensity to acquire the native conformation greatly depends on the peptide sequence, numerous empirical oxidation methods are employed. The context‐dependent optimization of these methods has thus far precluded a generalized oxidative folding protocol, in particular for peptides containing more than two disulfides. Herein, we compare the efficacy of optimized solution‐phase and polymer‐supported oxidation methods using three disulfide‐bridged conotoxins, namely µ‐SIIIA, µ‐KIIIA and ω‐GVIA. The use of diselenide bridges as proxies for disulfide bridges is also evaluated. We propose the ClearOx‐assisted oxidation of selenopeptides as a fairly generalized oxidative folding protocol. Copyright © 2010 European Peptide Society a

ISSN:1075-2617    

DOI:10.1002/psc.1283

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractPeptide nucleic acids (PNAs) are DNA mimics with a neutral peptide backbone instead of the negatively charged sugar phosphates. PNAs exhibit several attractive features such as high chemical and thermal stability, resistance to enzymatic degradation, and stable binding to their RNA or DNA targets in a sequence‐specific manner. Therefore, they are widely used in molecular diagnosis of antisense‐targeted therapeutic drugs or probes and in pharmaceutical applications. However, the main hindrance to the effective use of PNAs is their poor uptake by cells as well as the difficult and laborious chemical synthesis. In order to achieve an efficient delivery of PNAs into cells, there are already many published reports of peptides being used for transport across the cell membrane. In this protocol, we describe the automated as well as cost‐effective semi‐automated synthesis of PNAs and PNA‐peptide constructs on an automated peptide synthesizer. The facile synthesis of PNAs will be helpful in generating PNA libraries usable, e.g. for high‐throughput screening in biomolecular studies. Efficient synthetic schemes, the automated procedure, the reduced consumption of costly reagents, and the high purity of the products are attractive features of the reported procedure. Copyright © 2010 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.1305

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractIn this work we have probed the interactions of the amyloid Aβ(1–42) peptide with self‐assembled nanospheres. The nanospheres were formed by self‐assembly of a newly developed bolaamphiphile bis(N‐alpha‐amido‐methionine)‐1,8 octane dicarboxylate under aqueous conditions. It was found that the interactions of the Aβ(1–42) peptide with the nanospheres were concentration as well as pH dependent and the peptide largely adopts a random coil structure upon interacting with the nanospheres. Further, upon incorporation with the nanospheres, we observed a relative diminution in the aggregation of Aβ(1–42) at low concentrations of Aβ(1–42). The interactions between the nanospheres and the Aβ(1–42) peptide were investigated by atomic force microscopy, transmission electron microscopy, circular dichroism, FTIR and fluorescence spectroscopy, and the degree of fibrillation in the presence and absence of nanospheres was monitored by the Thioflavine T assay. We believe that the outcome from this work will help further elucidate the binding properties of Aβ peptide as well as designing nanostructures as templates for further investigating the nucleation and fibrillation process of Aβ‐like peptides. Copyright © 2010 European Peptide S

ISSN:1075-2617    

DOI:10.1002/psc.1284

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractThree peptide‐based systems integrating B and T antigenic sites of CSFV and displaying the B epitopes in fourfold presentation have been designed and produced, and shown to bring about significant enhancements in immunogenicity over the peptides in monomeric form. Of the different strategies tested for producing the dendrimeric constructs, stepwise SPPS using 3,6‐dioxaoctanoic acid as flexible, PEG‐like spacer units at the branching points is clearly advantageous, in particular over ligation in solution. The constructs have been used for immunization of domestic pigs, in order to evaluate the protective response induced by each peptide constructs, and to characterize the B‐ and T‐cell response against CSFV in the natural host. Copyright © 2010 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.1292

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractThe synthesis of difficult peptide sequences has been a challenge since the very beginning of SPPS. The self‐assembly of the growing peptide chains has been proposed as one of the causes of this synthetic problem. However, there is an increasing need to obtain peptides and proteins that are prone to aggregate. These peptides and proteins are generally associated with diseases known asamyloidoses. We present an efficient SPPS of two homologous peptide fragments of HuPrP (106–126) and MoPrP105–125 based on the use of the PEGA resin combined with proper coupling approaches. These peptide fragments were also studied by CD and TEM to determine their ability to aggregate. On the basis of these results, we support PEG‐based resins as an efficient synthetic tool to prepare peptide sequences prone to aggregate on‐resin. Copyright © 2010 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.1293

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractOwing to the high chemoselectivity between an aminooxy function and a carbonyl group, oxime ligation is one of the most preferred procedures for the preparation of peptide conjugates. However, the sensitivity of (aminooxy)acetylated peptides to ketones and aldehydes makes their synthesis and storage difficult. In our study, we established the efficient synthesis of an (aminooxy)acetylated‐somatostatin derivative in the presence of free (aminooxy)acetic acid, which was used as a ‘carbonyl capture’ reagent in the final cleavage step. This (aminooxy)acetylated compound was further used for the chemoselective ligation (oxime bond formation) with daunorubicin and 4‐fluorobenzaldehyde leading to the formation of conjugates with potential applications in targeted cancer chemotherapy and positron emission tomography. Copyright © 2010 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.1294

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

Abstractα‐melanocyte stimulating hormone (α‐MSH) is a tridecapeptide fragment of pro‐opiomelanocortin (POMC) with broad effects on appetite, skin pigmentation, hormonal regulation, and potential roles in both inflammation and autoimmunity. The use of this peptide as an anti‐inflammatory agent is limited by its low selectivity between the melanocortin receptors, susceptibility to proteolytic degradation, and rapid clearance from circulation. A retro‐inverso (RI) sequence of α‐MSH was characterized for receptor activity and resistance to protease. This peptide demonstrated surprisingly high selectivity for binding the melanocortin receptor 1 (MC1R). However, RI‐α‐MSH exhibited a diminished binding affinity for MC1R compared to α‐MSH. Mapping of the residues critical for agonist activity, receptor binding, and selectivity by alanine scanning, identified the same critical core tetrapeptide required for the native peptide. Modest improvements in affinity were obtained by conservative changes employing non‐natural amino acids and substitution of theC‐terminal sequence with a portion of a MC1R ligand peptide previously identified by phage display. Recombination of these elements yielded a peptide with an identicalKias α‐MSH at MC1R and a lower EC50in Mel‐624 melanoma cells. A number of other structural modifications of the RI peptide were found to differ in effect from those reported for theL‐form α‐MSH, suggesting a significantly altered interaction with the MC1R. Copyright © 2010 European Pep

ISSN:1075-2617    

DOI:10.1002/psc.1306

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractIn some naturally occurring protein sequences, an abrupt, concerted refolding from β‐sheet to helical conformation occurs when the polarity of the surrounding medium drops below a critical level. This switch‐like behaviour was first observed on the HIV‐1 envelope glycoprotein gp120, where it plays a crucial role in the efficient binding of gp120 to the T‐cell receptor CD4. Previous work had shown that anN‐terminal amino acid tetrad LPCR and a Trp located 5–20 residues downstream to the tetrad are common motifs in polarity‐driven switch peptides. The LPCR tetrad governs the folding of the subsequent residues and acts as a helix initiation site, whereas the Trp is responsible for the cooperative character of the structural change due to multiple, simultaneous interactions of its quadrupole moment with several amino acid residues within the sequences. Here we identify and characterize new families of switch peptides that use different, turn‐probable tetrads (LPST and VPSR) as helix initiation sites at theN‐terminus. We have also been able to demonstrate that some tetrads with extremely high turn probability do not serve as helix initiation sites. Comparison of these with LPCR and the newly discovered tetrads LPST and VPSR has allowed a more comprehensive description of the physico‐chemical properties of helix‐inducing tetrads. The deeper understanding of the intrinsic properties of switch sequences allows the design of artificial polarity‐driven switches, applicable in engineering of, e.g. controllable binding sites in artificial proteins. Copyright © 2010 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.1296

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractTwo novel antimicrobial peptides with similarity to brevinin‐2 family are purified and characterized from the skin secretions of the frog,Rana nigrovittata. Their amino acid sequences were determined as GAFGNFLKGVAKKAGLKILSIAQCKLSGTC (brevinin‐2‐RN1) and GAFGNFLKGVAKKAGLKILSIAQCKLFGTC (brevinin‐2‐RN2), respectively, by Edman degradation. Different from brevinin‐2, which is composed of 33 amino acid residues (aa), bothbrevinin‐2‐RN1 and ‐RN2contain 30 aa. Five cDNA sequences (Genbank accession numbers, EU136465‐9) encoding precursors ofbrevinin‐2‐RN1 and ‐RN2were screened from the skin cDNA library ofR. nigrovittata. These precursors are composed of 72 aa including a predicted signal peptide, an acidic spacer peptide, and a maturebrevinin‐2‐RN. Bothbrevinin‐2‐RN1 and ‐RN2showed strong antimicrobial activities against gram‐positive and gram‐negative bacteria and fungi. The current work identified and characterized two novel antimicrobial peptides with unique primary structure. Copyright © 2010 European

ISSN:1075-2617    

DOI:10.1002/psc.1309

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY