摘要:

AbstractPeptides and proteins are highly dynamic systems, which can adopt more or less stable conformations. The dynamics of these molecules, particularly those on the nanosecond to tens of microsecond time scale, are difficult to assess with conventional techniques. This review summarizes experiments using TTET, a technique that reports on van der Waals contact formation between a triplet donor and acceptor group, and which is sensitive in this time range. TTET allows to directly measure the chain dynamics of unstructured model peptides, i.e. large‐amplitude fluctuations on the nanosecond time scale. Furthermore, contact formation can be used as irreversible probing reaction to study the kinetics of conformational equilibria. This approach enabled us to measure local α‐helix folding and unfolding in helical peptides, which gave new insight into the equilibrium dynamics of this fundamental secondary structure element. TTET has also been applied to study the dynamics both in the native and unfolded state of a protein, the villin headpiece subdomain. The contact formation kinetics between different positions revealed an unlocking and local unfolding reaction in the native state of this model protein, and gave information about the chain dynamics in the unfolded state ensemble. Copyright © 2011 European Peptide Society and John Wiley&Sons

ISSN:1075-2617    

DOI:10.1002/psc.1353

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractFour diastereomeric‐Leu‐Leu‐Aib‐Leu‐Leu‐Aib‐peptides, Boc‐D‐Leu‐L‐Leu‐Aib‐L‐Leu‐L‐Leu‐Aib‐OMe (1), Boc‐L‐Leu‐D‐Leu‐Aib‐L‐Leu‐L‐Leu‐Aib‐OMe (2), Boc‐L‐Leu‐L‐Leu‐Aib‐D‐Leu‐L‐Leu‐Aib‐OMe (3), and Boc‐L‐Leu‐L‐Leu‐Aib‐L‐Leu‐D‐Leu‐Aib‐OMe (4), were synthesized. The crystals of the four hexapeptides were characterized by X‐ray crystallographic analysis. Two diastereomeric hexapeptides 1 and 2 havingD‐Leu(1) orD‐Leu(2) were folded into right‐handed (P) 310‐helical structures, while peptide 3 havingD‐Leu(4) was folded into a turn structure nucleated by type III′ and I$' \bf{\beta}$‐turns, and peptide 4 havingD‐Leu(5) was

ISSN:1075-2617    

DOI:10.1002/psc.1332

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractProtein (lectin/toxin)–glycan interaction can be clinically harmful so that the design of inhibitors has become an aim. Cyclic decapeptides are suited as rigid carriers for carbohydrate derivatives. We herein document the bioactivity of sugar headgroups covalently attached to this carrier for the cases of five proteins, i.e. a potent biohazardous plant agglutinin, a leguminous model lectin and three adhesion/growth‐regulatory human lectins. They represent the different types of topological organization within the galectin family. The relative inhibitory activities of glycoclusters with the three ligands (galactose, lactose and the disaccharide of the Thomsen‐Friedenreich antigen) reflected the affinity of free carbohydrates, hereby excluding an impairment of binding activity by chemical derivatization and conjugation. Headgroup tailoring is thus one route to optimize activity and selectivity of cyclopeptide‐based glycoclusters. The increase of ligand density from tetra‐ to hexadecavalency added a second route. The plant toxin and tandem‐repeat‐type galectin‐4 were especially sensitive to this parameter change. Strategically combining solid‐phase assays for screening with analysis of lectin binding to cells in different systems revealed efficient inhibition by distinct glycoclusters, thereby protecting cells from lectin association. Cyclic neoglycodecapeptides thus warrant further study as lectin‐directed pharmaceuticals. Copyright © 2011 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.1338

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractNisin is a peptide bacteriocin, grouped under the category of lantibiotics. It is naturally produced byLactococcus lactisto eliminate other competing gram‐positive bacteria from its vicinity. Moreover under certain conditions it is reported to be effective against a broad range of gram‐negative bacteria as well. Thus, it has been widely used as a safe food preservative especially in the dairy industry. Because of its wide‐scale consumption, its effect on eukaryotic cells should be of great concern. Here we examine the immunomodulatory efficacy of nisinin vitro. MTT‐based cytotoxicity assay demonstrated nisin's cytotoxicity on human T‐cell lymphoma Jurkat cells, Molt‐4 cells and freshly cultured human lymphocytes at over 200 µMconcentration (IC50225 µM). The cell death mechanism induced by nisin in all these lymphocyte types was independent of oligonucleosomal DNA fragmentation, as analyzed by agarose gel electrophoresis and comet assay. Additionally, scanning electron microscope and fluorescence microscopy demonstrated the ability of nisin to activate human PMNsin vitro. Nisin‐activated neutrophils extruded intact nuclear chromatin to form NETs, well known for neutralization of virulence factors and extermination of bacterial pathogens. Nisin's presence also elevated neutrophil intracellular superoxide levels, normally produced by activated NADPH oxidase and prerequisite to NET formation. These nisin‐induced responses in cellular representatives of two separate branches of human immune system—adaptive and innate—although leading to cell death, did not include DNA fragmentation. From these findings, we propose that nisin might trigger similar AICD mechanisms in lymphocytes and neutrophils, different from conventional apoptosis which involves DNA fragmentation. Copyright © 2011 European Peptide Society an

ISSN:1075-2617    

DOI:10.1002/psc.1341

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractA series of model peptides in the form of quaternary ammonium salts at theN‐terminus was efficiently prepared by the solid‐phase synthesis. Tandem mass spectrometric analysis of the peptide quaternary ammonium derivatives was shown to provide sequence confirmation and enhanced detection. We designed the 2‐(1,4‐diazabicyclo[2.2.2] octylammonium)acetyl quaternary ammonium group which does not suffer from neutral losses during MS/MS experiments. The presented quaternization of 1,4‐diazabicyclo[2.2.2]octane (DABCO) by iodoacetylated peptides is relatively easy and compatible with standard solid‐phase peptide synthesis. This methodology offers a novel sensitive approach to analyze peptides and other compounds. Copyright © 2011 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.1342

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractScreening, isolation andin vitroassays have been used for characterization of antioxidative peptides derived from food proteins, and incompatible deductions of structural characteristics derived from the isolated peptides have been brought forward. However, there is still little information concerning the structure‐activity relationship of antioxidative peptides. QSAR modeling was performed, respectively, on synthetic tripeptides and tetrapeptides related to LLPHH. According to cumulative squared multiple correlation coefficients (R2), cumulative cross‐validation coefficients (Q2) and relative standard deviation for calibration set (RSDc), two credible models for tripeptide and tetrapeptide databases, respectively, have been built with partial least squares (PLS) regression (R2for models of tripeptide and tetrapeptide are 0.744 and 0.943,Q2are 0.631 and 0.414, and RSDcare 0.323 and 0.111, respectively). Meanwhile, according to the cumulative multiple correlation coefficient for the predictive set ($R_{\rm {ext}}^{2}$) and the relative standard deviation for the predictive set (RSDp), the predictive ability of the model for tripeptides also is excellent ($R_{\rm {ext}}^{2}$and RSDpare 0.719 and 0.450, respectively). Hydrogen bond property and hydrophilicity of the amino acid residue next to theC‐terminus, and the hydrophobicity as well as electronic propertyof theN‐terminus are more significant; meanwhile, the electronic property of theC‐terminus is beneficial for antioxidant activity. The structural characteristics we found are very useful in understanding and predicting the peptide structures responsible for activity and development of functional foods with peptides as active compounds, or antioxidative peptides as alternatives to other antioxidants. Copyright © 2011 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.1345

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractThe Z‐molecule is a small, engineered IgG‐binding affinity protein derived from the immunoglobulin‐binding domain B ofStaphylococcus aureusprotein A. The Z‐domain consists of 58 amino acids forming a well‐defined antiparallel three‐helix structure. Two of the three helices are involved in ligand binding, whereas the third helix provides structural support to the three‐helix bundle. The small size and the stable three‐helix structure are two attractive properties comprised in the Z‐domain, but a further reduction in size of the protein is valuable for several reasons. Reduction in size facilitates synthetic production of any protein‐based molecule, which is beneficial from an economical viewpoint. In addition, a smaller protein is easier to manipulate through chemical modifications. By omitting the third stabilizing helix from the Z‐domain and joining theN‐ andC‐termini by a native peptide bond, the affinity protein obtains the advantageous properties of a smaller scaffold and in addition becomes resistant to exoproteases. We here demonstrate the synthesis and evaluation of a novel cyclic two‐helix Z‐domain. The molecule has retained affinity for its target protein, is resistant to heat treatment, and lacks bothN‐ andC‐termini. Copyright © 2011 European Peptid

ISSN:1075-2617    

DOI:10.1002/psc.1346

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractConventional dendrimers are spherical symmetrically branched polymers ending with active surface functional groups. Polyamidoamine (PAMAM) dendrimers have been widely studied as gene delivery vectors and have proven effective at delivering DNA to cellsin vitro. However, higher‐generation (G4‐G8) PAMAM dendrimers exhibit toxicity due to their high cationic charge density and this has limited their applicationin vitroandin vivo. Another limitation arises when attempts are made to functionalize spherical dendrimers as targeting moieties cannot be site‐specifically attached. Therefore, we propose that lower‐generation asymmetric dendrimers, which are likely devoid of toxicity and to which site‐specific attachment of targeting ligands can be achieved, would be a viable alternative to currently available dendrimers. We synthesized and characterized a series of peptide‐based asymmetric dendrimers and compared their toxicity profile and ability to condense DNA to spherical PAMAM G1 dendrimers. We show that asymmetric dendrimers are minimally toxic and condense DNA into stable toroids which have been reported necessary for efficient cell transfection. This paves the way for these systems to be conjugated with targeting ligands for gene deliveryin vitroandin vivo. Copyright © 2011 European Peptide Society and John Wil

ISSN:1075-2617    

DOI:10.1002/psc.1347

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY

摘要:

AbstractEffective surface modification with biocompatible molecules is known to be effective in reducing the life‐threatening risks related to artificial cardiovascular implants. In recent strategies in regenerative medicine, the enhancement and support of natural repair systems at the site of injury by designed biocompatible molecules have succeeded in rapid and effective injury repair. Therefore, such a strategy could also be effective for rapid endothelialization of cardiovascular implants to lower the risk of thrombosis and stenosis. To achieve this enhancement of the natural repair system, a biomimetic molecule that mimics proper cellular organization at the implant location is required. In spite of the fact that many reported peptides have cell‐attracting properties on material surfaces, there have been few peptides that could control cell‐specific adhesion. For the advanced cardiovascular implants, peptides that can mimic the natural mechanism that controls cell‐specific organization have been strongly anticipated. To obtain such peptides, we hypothesized the cellular bias toward certain varieties of amino acids and examined the cell preference (in terms of adhesion, proliferation, and protein attraction) of varieties and of repeat length on SPOT peptide arrays. To investigate the role of specific peptides in controlling the organization of various cardiovascular‐related cells, we compared endothelial cells (ECs), smooth muscle cells (SMCs), and fibroblasts (FBs). A clear, cell‐specific preference was found for amino acids (longer than 5‐mer) using three types of cells, and the combinational effect of the physicochemical properties of the residues was analyzed to interpret the mechanism. Copyright © 2011 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/psc.1355

出版商:John Wiley&Sons, Ltd.    

年代:2011

数据来源: WILEY