摘要:

AbstractA 1905‐Da cationic proline‐rich peptide, named SP‐B, was recently isolated by our group as the main component of salivary gland granules, and its primary sequence fully characterized by means of automated Edman sequencing and LC‐MS/MS tools. In the present study SP‐B is shown to possess antifungal activity when challenged with strains ofCryptococcus neoformans, Candida albicansandAspergillus fumigatus, while only negligible antibacterial activity was detected. Furthermore, SP‐B was found to be non‐cytotoxic when tested on fibroblast cell lines. To obtain information regarding its structure affinity, capillary electrophoresis (CE), circular dichroism (CD) and attenuated total reflection (ATR)‐FT/IR experiments were performed. CE revealed a pH dependence of the hydrodynamic radial dimensions both in aqueous and 2,2,2‐trifluoroethanol solutions. CD and ATR‐FT/IR measurements confirmed the structure–pH relationship, revealing a secondary structure composed of mixed proportions of polyproline‐II, unordered and turn motifs, the last being more evident in the zwitterionic form of the peptide. From these findings SP‐B peptide could be classified as a new member of the proline‐rich antimicrobial peptide family. Copyright © 2007 European Peptide Soci

ISSN:1075-2617    

DOI:10.1002/psc.914

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe human neuregulin 1‐β1 (NRG1‐β1, amino acid residues 176–246) was chemically synthesized by Fmoc‐based solid phase peptide synthesis (SPPS) followed by folding in a redox buffer. The biological activity of the synthesized NRG1‐β1 was confirmed by ligand‐induced tyrosine phosphorylation on Chinese hamster ovary (CHO) cells expressing ErbB‐4. Copyright © 2007 European Peptide Society and Joh

ISSN:1075-2617    

DOI:10.1002/psc.916

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

Abstractω‐AGA IVB is an important lead structure when considering the design of effectors of glutamate release inducting P/Q‐type calcium channels. The best route to achieve the analogues possessing the three‐dimensional arrangement corresponding to the native binding loop was the introduction of constraint by ring formation via side chain to side chain lactamization for suitably protected Lys and Glu residues. Since tryptophane residue located at position 14 of this neuropeptide has been suggested as essential for binding, analogues in which this amino acid was replaced by aza‐tryptophane and alanine were synthesized. The synthesis was carried out on various acid‐labile resins (BARLOS chlorotrityl, Rink amide, PEG‐based or Wang resins), by Fmoc strategy. In this paper, we describe optimization of the peptide cyclization with various protecting groups, and on resin or in solution cyclization experimental parameters. Copyright © 2007 European Peptide Society and John Wi

ISSN:1075-2617    

DOI:10.1002/psc.919

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractA trypsin inhibitor, with anN‐terminal sequence highly homologous to those of 8‐kDa Bowman‐Birk trypsin inhibitors, was isolated from the seeds of Hokkaido large black soybeans. The trypsin inhibitor was unadsorbed on SP‐Sepharose but adsorbed on DEAE‐cellulose and Mono Q. It inhibited proliferation in breast cancer (MCF‐7) cells and hepatoma (Hep G2) cells with an IC50of 35 and 140 µM, respectively. The trypsin inhibitory activity of the inhibitor was completely preserved after exposure to temperatures up to 100 °C for 30 min and to the pH range 2–13 for the same duration. The trypsin inhibitor inhibited HIV‐1 reverse transcriptase with an IC50of 38 µM, but was devoid of antifungal activity towardFusarium oxysporumandMycosphaerella arachidicola. Copyright © 2007 European Peptide Society and J

ISSN:1075-2617    

DOI:10.1002/psc.922

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe circular dichroism (CD) and Fourier transform infrared (FTIR) methods were applied to the conformational studies of alanine‐rich peptide Ac‐K‐[A]11‐KGGY‐NH2(where K is lysine, A is alanine, G is glycine and Y is tyrozyne) in water, methanol (MeOH) and trifluoroethanol (TFE). The analysis of CD‐spectra of the peptide in water at different concentrations revealed that the secondary structure content depends on the peptide concentration and pH of the solution. The increase of the peptide concentration causes a decrease of α‐helix content and, simultaneously, an increase of β‐sheet structure, while the unordered structure is the predominant one. Additional elements are discovered in MeOH and TFE but α‐helix and β‐turns predominate. Moreover, in these solutions the percentage content of the secondary structure does not depend on the temperature. FTIR measurements, carried out at higher peptide concentration (about one order of magnitude) than these CD measurements mentioned above, revealed that in water solution the solid state β‐sheet, and aggregated structures, dominate. However, in TFE the most abundant are α‐helix and β‐turns structures. The thioflavine T assay showed the tendency of the studied peptide for aggregate. Copyright © 2007 European Peptide

ISSN:1075-2617    

DOI:10.1002/psc.923

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractWe havede novodesigned four antimicrobial peptides AMP‐A/B/C/D, the 51‐residues peptides, which are based on the conserved sequence of cecropin. In the present study, the four peptides were chemically synthesized and their activities assayed. Their secondary structure, amphipathic property, electric field distribution and transmembrane domain were subsequently predicted by bioinformatics tools. Finally, the structure–activity relationship was analyzed from the results of activity experiments and prediction. The results of activity experiments indicated that AMP‐B/C/D clearly possessed excellent broad‐spectrum activity against bacteria, whereas AMP‐A was almost inactive against most of the bacterial strains tested. AMP‐B/C/D showed more potent activity against Gram‐positive bacteria than against Gram‐negative bacteria. By utilizing bioinformatics analysis tools, we found that the secondary structure of the four cation peptides was mainly α‐helix, and the result of CD spectrum also displayed that all the peptides had considerable α‐helix in the presence of either 50% TFE or SDS micelles. AMP‐C showed much better activity than other peptides against most of the bacteria tested, owing to its remarkable cation property and the amphipathic character of itsN‐terminal. The study of structure–activity relationship of the designed peptides confirmed that amphipathic structure and high net positive charge were prerequisites for maintaining their activities. Copyright © 2007 European Peptide So

ISSN:1075-2617    

DOI:10.1002/psc.926

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractA promising application of the depsipeptide technique has recently been proposed to provide ideal conditions for segment condensation, in that coupling of peptides bearing aC‐terminal depsipeptide unit occurs without giving rise to epimerization at the activated amino acid. This is due to the low tendency of the activated depsipeptide units, in contrast to the corresponding peptide segments, to form optically labile oxazolones. In this work we demonstrate that coupling of depsipeptides via base‐assisted activation using HBTU occurs not only without loss of configuration, but even much faster than the coupling of the corresponding all‐amide segments. Nevertheless, when the coupling of long depsipeptide segments proceeds slowly, we uncovered the occurrence of β‐elimination at the activated depsipeptide unit, in an extent dependent on the presence of base in the system and on the type of the solvent. Beta‐elimination was completely suppressed by using carbodiimide/HOBt activation in a non‐polar solvent (DCM), and in more polar media it was limited by substituting TMP for DIEA during HBTU activation, or using particular solvent mixtures (such as DMSO/toluene) for activation via carbodiimide. Finally, we show the application ofC‐terminal pseudoprolines, in comparison with that of depsipeptide units, to segment coupling. Copyright © 2007 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.928

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractAs a hepatitis B virus (HBV) envelope domain, preS plays significant roles in receptor recognition and viral infection. However, the regions critical for maintaining a stable and functional conformation of preS are still unclear and require further investigation. In order to unravel these regions, serially truncated fragments of preS were constructed and expressed inEscherichia coli. Their solubility, stability, secondary structure, and affinity to polyclonal antibodies and hepatocytes were examined. The results showed that amino acids 31–36 were vital for its stable conformation, and the absence of 10–36 amino acids significantly reduced its binding to polyclonal antibodies as well as hepatocytes. The most stable fragment 1–120 (preS1 +N‐terminal 12 amino acids of preS2), perhaps the core of preS, was discovered, which bound to HepG2 cells most tightly. Moreover, the availability of large amounts of well‐folded and stable preS1‐120 enables us to carry out further structural determination and mechanistic study on HBV infection. Copyright © 2007 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.929

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe effect of substituting unnatural hydrophobic amino acids into the critical MHC binding residues of an HLA‐A*0201‐restricted cytomegalovirus CMVpp65 epitope, NLVPMVATV, has been investigated. A new set of peptides containing the amino acidstert‐butyl glycine (Tgl), cyclohexyl glycine (Chg),neo‐pentyl glycine (Npg), cyclohexyl alanine (Cha) and cyclo leucine (Cyl), at either position 2, to mimic Leu, or position 9, to mimic Val, have been synthesised. Immunological profiling using class I MHC stabilisation assays to assess MHC binding affinity, and enzyme‐linked immunospot (ELISPOT) assays to assess the ability of the modified peptides to re‐stimulate a specific cytotoxic T‐lymphocyte (CTL) response, compared to the native epitope, have been performed. It was found that the majority of the unnatural substitutions resulted in a decrease in either HLA‐A*0201 binding affinity or cytotoxic T‐cell activity. However, the HLA‐A*0201 binding affinity was unrelated to the ability to re‐stimulate a T‐cell response. Minimisation and molecular dynamics studies proved helpful in dissecting the ELISPOT responses. Two principal peptide binding modes were found by minimisation, designated kinked and straight. Peptides that bound in a kinked conformation were poor at re‐stimulating a T‐cell response. Of the peptides that bound in a straight conformation, molecular dynamics (MD) simulations revealed that those capable of re‐stimulating the strongest responses had the greatest degree of flexibility (as determined by RMSD values across the MD simulation) around the P6 residue, one of the residues important for T‐cell receptor recognition. Copyright © 2007 European Peptide

ISSN:1075-2617    

DOI:10.1002/psc.930

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractVasoactive intestinal peptide (VIP) is a prominent neuropeptide, exhibiting a wide spectrum of biological activities in mammals. However, the clinical applications of VIP are mainly hampered because of its rapid degradationin vivo. Peptide glycosylation, a procedure frequently used to increase peptide resistance to proteolytic degradation and consequently increase peptide metabolic stability, has not been performed yet on VIP. The presence of threeN‐glycosylation sites on VIP receptor type 1 (VPAC1) was previously demonstrated. Therefore, glycosylation of the VIP ligand could potentially increase its receptor affinity because of glyco–glyco interactions between the ligand and the receptor. In order to enhance VIP's metabolic stability and to increase its ligand–receptor binding/activation, eight glycosylated VIP derivatives were successfully synthesized by the solid‐phase procedure. Each VIP analog was monoglycosylated by a monosaccharide addition to one amino‐acid residue along the sequence. Glycosylation did not affect the α‐helical structure shown by the native VIP in organic environment. Few glycosylated VIP analogs displayed highly potent VPAC1 receptor binding and cAMP‐induced activation; only 4–6 fold lower in comparison to the native VIP. Furthermore, the peptide analog glycosylated on Thr11([11Glyc]VIP) showed a significantly enhanced stability toward trypsin enzymatic degradation in comparison to VIP. Analysis of the degradation products of [11Glyc]VIP showed that differently from VIP, incubation of the peptide [11Glyc]VIP with trypsin resulted in no cleavage at the Arg12–Leu13peptide bond, suggesting that VIP glycosylation may lead to enhanced metabolic stability. Copyright © 2007 European Peptide Society and J

ISSN:1075-2617    

DOI:10.1002/psc.932

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY