摘要:

AbstractNon‐ribosomally synthesized microbial peptides show remarkable structural diversity and constitute a widespread class of the most potent antibiotics and other important pharmaceuticals that range from penicillin to the immunosuppressant cyclosporine. They are assembled independent of the ribosome in a nucleic acids‐independent way by a group of multimodular megaenzymes called non‐ribosomal peptide synthetases. These biosynthetic machineries rely not only on the 20 canonical amino acids, but also use several different building blocks, includingD‐configured‐ and β‐amino acids, methylated, glycosylated and phosphorylated residues, heterocyclic elements and even fatty acid building blocks. This structural diversity leads to a high density of functional groups, which are often essential for the bioactivity. Recent biochemical and structural studies on several non‐ribosomal peptide synthetase assembly lines have substantially contributed to the understanding of the molecular mechanisms and dynamics of individual catalytic domains underlying substrate recognition and substrate shuffling among the different active sites as well as peptide bond formation and the regio‐ and stereoselective product release. Copyright © 2009 European Peptide Society and Joh

ISSN:1075-2617    

DOI:10.1002/psc.1183

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractSeveral conditions have been used in the coupling reaction of stepwise SPPS at elevated temperature (SPPS‐ET), but we have elected the following as our first choice: 2.5‐fold molar excess of 0.04–0.08 M Boc or Fmoc‐amino acid derivative, equimolar amount of DIC/HOBt (1:1) or TBTU/DIPEA (1:3), 25% DMSO/toluene, 60 °C, conventional heating. In this study, aimed to further examine enantiomerization under such condition and study the applicability of our protocols to microwave‐SPPS, peptides containingL‐Ser,L‐His,L‐Cys and/orL‐Met were manually synthesized traditionally, at 60 °C using conventional heating and at 60 °C using microwave heating. Detailed assessment of all crude peptides (in their intact and/or fully hydrolyzed forms) revealed that, except for the microwave‐assisted coupling ofL‐Cys, all other reactions occurred with low levels of amino acid enantiomerization (<2%). Therefore, herein we (i) provide new evidences that our protocols for SPPS at 60 °C using conventional heating are suitable for routine use, (ii) demonstrate their appropriateness for microwave‐assisted SPPS by Boc and Fmoc chemistries, (iii) disclose advantages and limitations of the three synthetic approaches employed. Thus, this study complements our past research on SPPS‐ET and suggests alternative conditions for microwave‐assisted SPPS. Copyright © 2009 European Peptide

ISSN:1075-2617    

DOI:10.1002/psc.1178

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe structure of Peptide T was determined by solution NMR spectroscopy, under strong structure‐inducing conditions: 40% hexafluoro‐2‐propanol aqueous solution at 5 °C. Under these conditions it was possible to detect medium‐range NOEs for the first time for this peptide. This allowed a much better‐defined structure to be determined for Peptide T in comparison with earlier NMR and computational studies. Peptide structures consistent with the experimental restraints were generated using a restrained MD simulation with a full empirical force field. Residues 4–8 of Peptide T take on a well‐defined structure with a heavy atom RMSD of 0.78 Å. The structure is stabilized by hydrogen bonding to side‐chain oxygen atoms of Thr 4 and Thr 8, as well as backbone hydrogen bonding between residues 5 and 7 that forms this region into a classic γ‐turn. Copyright © 2009 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.1179

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe RING finger domain of the Mdm2, located at theC‐terminus of the protein, is necessary for regulation of p53, a tumor suppressor protein. The 48‐residues long Mdm2 peptide is an important target for studying its interaction with small anticancer drug candidates. For the chemical synthesis of the Mdm2 RING finger domain, the fragment condensation on solid‐phase and the fragment condensation in solution were studied. The latter method was performed using either protected or free peptides at theC‐terminus as the amino component. Best results were achieved using solution condensation where theN‐component was applied with theC‐terminal carboxyl group left unprotected. The developed method is well suited for large‐scale synthesis of Mdm2 RING finger domain, combining the advantages of both solid‐phase and solution synthesis. Copyright © 2009 European Peptide Society and John

ISSN:1075-2617    

DOI:10.1002/psc.1182

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractIt is well known that the functions of metalloproteins generally originate from their metal‐binding motifs. However, the intrinsic nature of individual motifs remains unknown, particularly the details about metal‐binding effects on the folding of motifs; the converse is also unknown, although there is no doubt that the motif is the core of the reactivity for each metalloprotein. In this study, we focused our attention on the zinc‐binding motif of the metzincin clan family, HEXXHXXGXXH; this family contains the general zinc‐binding sequence His–Glu–Xaa–Xaa–His (HEXXH) and the extended GXXH region. We adopted the motif sequence of stromelysin‐1 and investigated the folding properties of the Trp‐labeled peptides WAHEIAHSLGLFHA (STR‐W1), AWHEIAHSLGLFHA (STR‐W2), AHEIAHSLGWFHA (STR‐W11), and AHEIAHSLGLFHWA (STR‐W14) in the presence and absence of zinc ions in hydrophobic micellar environments by circular dichroism (CD) measurements. We accessed successful incorporation of these zinc peptides into micelles using quenching of Trp fluorescence. Results of CD studies indicated that two of the Trp‐incorporated peptides, STR‐W1 and STR‐W14, exhibited helical folding in the hydrophobic region of cetyltrimethylammonium chloride micelle. The NMR structural analysis of the apo STR‐W14 revealed that the conformation in theC‐terminus GXXH region significantly differred between the apo state in the micelle and the reported Zn‐bound state of stromelysin‐1 in crystal structures. The structural analyses of the qualitative Zn‐binding properties of this motif peptide provide an interesting Zn‐binding mechanism: the minimum consensus motif in the metzincin clan, a basic zinc‐binding motif with an extended GXXH region, has the potential to serve as a preorganized Zn binding scaffold in a hydrophobic environment. Copyright © 2009 E

ISSN:1075-2617    

DOI:10.1002/psc.1184

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractAntimicrobial peptides are small molecular weight proteins with a large antibacterial spectrum. They can reach high local concentrations in tissues with active inflammation, being largely produced by immunocompetent cells. However, their effect on eukaryotic cells is still unclear. We have, therefore, studied three structurally different antimicrobial peptides (cecropin P1, PR‐39 and NK‐lysin) for their cytotoxic effects on blood mononuclear cells. None of the antimicrobial peptides tested exhibited significant cytotoxic effect on resting lymphocytes isolated either from peripheral blood or from the spleen with the exception of high concentrations (ten times higher than IC100 forEscherichia coli) of NK‐lysin. Activated lymphocytes were, however, more sensitive to the cytotoxic effect of the antimicrobial peptides. Both activated T‐cells and B‐cells were dose dependent sensitive to NK‐lysin while only activated B‐cells but not activated T‐cells were sensitive to PR‐39. Cecropin did not exhibit any cytotoxic effect on activated lymphocytes either. By using several cell lines (3B6, K562, U932 and EL‐4) we were able to show that NK‐lysin has a broad necrotic effect while PR‐39 has a cell specific apoptotic effect dependent on the specifically cellular uptake. In conclusion we show here that antimicrobial peptides are not cytotoxic for the resting eukaryotic cells but can be cytotoxic on activated immune cells through distinct mechanisms of cell death. Copyright © 2009 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.1185

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractProtection of the amino group and activation of the carboxylic acid groups are the most important steps associated with any peptide synthesis protocol; hence, a one‐pot process to achieve these is highly desirable. A possible strategy is to use pentafluorophenyl carbonates to simultaneously protect the amino group as a carbamate derivative and activate the carboxylic acid group as a pentafluorophenyl ester. A detailed study is carried out to understand the scope and limitations of this method using five different pentaflurophenyl carbonates. The efficiency of these one‐pot reactions depends largely on the nature of the pentafluorophenyl carbonates and also on the nature of the amino acids. Electron deficient and sterically less demanding carbonates reacted faster than the others, whereas amino acids with longer aliphatic side chains gave better yields than more polar amino acids. Copyright © 2009 European Peptide Society and John Wiley&Sons,

ISSN:1075-2617    

DOI:10.1002/psc.1187

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractSelective NPY analogues are potent tools for tumour targeting. Their Y1‐receptors are significantly over‐expressed in human breast tumours, whereas normal breast tissue only expresses Y2‐receptors. The endogenous peptide consists of 36 amino acids, whereas smaller peptides are preferred because of better labelling efficiencies. As Y1‐receptor agonists enhance the tumour to background ratio compared to Y1‐receptor antagonists, we were interested in the development of Y1‐receptor selective agonists. We designed 19 peptides containing theC‐terminus of NPY (28–36) with several modifications. By using competition receptor binding affinity assays, we identified three NPY analogues with high Y1‐receptor affinity and selectivity. Metabolic stability studies in human blood plasma of theN‐terminally 5(6)‐carboxyfluorescein (CF) labelled peptides resulted in half‐lives of several hours. Furthermore, the degradation pattern revealed proteolytic degradation of the peptides by amino peptidases. The most promising peptide was further investigated in receptor activation and internalization studies. Signal transduction assays revealed clear agonistic properties, which could be confirmed by microscopy studies that showed clear Y1‐receptor internalization. For the first time, here we show the design and characterization of a small Y1‐receptor selective agonist. This agonist might be a useful novel ligand for NPY‐mediated tumour diagnostics and therapeutics. Copyright © 2009 European Peptide So

ISSN:1075-2617    

DOI:10.1002/psc.1188

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY

摘要:

AbstractThe original article to which this Erratum refers was published in Journal of Peptide Science, 2009: 15: Pages 504‐5

ISSN:1075-2617    

DOI:10.1002/psc.1200

出版商:John Wiley&Sons, Ltd.    

年代:2009

数据来源: WILEY