ISSN:1075-2617    

DOI:10.1002/psc.1058

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractIn the present study, three Taiwan cobra PLA2variants were prepared by adding an extraN‐terminal Met, substituting Asn‐1 by Met or deleting theN‐terminal heptapeptide. Recombinant PLA2mutants were expressed inEscherichia coli(E. coli), and purified to homogeneity by reverse phase HPLC. Fluorescence measurement showed that the hydrophobic character of the catalytic site, the microenvironment of Trp residues and energy transfer from excited Trp to 8‐anilinonaphthalene sulfonate (ANS) were affected byN‐terminal mutations. An alteration in the structural flexibility of the active site was noted with the mutants lacking theN‐terminal heptapeptide or with an extraN‐terminal Met added as evidenced by the inability of the two variants to bind with Ba2+. Moreover, modification of Lys residues and energy transfer within the protein‐ANS complex revealed that the Ca2+‐induced change in the global structure of PLA2was different from that inN‐terminal variants. Together with the fact that an ‘activation network’ connects theN‐terminus with the active site, our data suggest that mutagenesis on theN‐terminal region affects directly the fine structure of the catalytic site, which subsequently transmits its influence in altering the structure outside the active site of PLA2. Copyright © 2008 European Peptide Soci

ISSN:1075-2617    

DOI:10.1002/psc.1020

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractTheN‐terminal tetrapeptide segments of dermorphin (Tyr–D‐Ala–Phe–Gly–Tyr–Pro–Ser–NH2) and deltorphin (Tyr–D‐Ala–Phe–Asp/Glu–Val–Val–Gly–NH2) are agonists at the opioid receptors µ and δ, respectively. [D‐Arg2, Lys4]‐dermorphin‐(1–4) amide (Tyr–D‐Arg–Phe–Lys–NH2, DALDA) and [Dmt1]DALDA (where Dmt is 2′,6′‐dimethyltyrosine) are among the most potent and selective µ‐agonists reported to date, bothin vitro(having picomolar µ receptor affinity) andin vivo. In this communication, conformation‐activity studies of the following four cyclic analogs of DALDA are presented and discussed: the lead peptideS2,S4‐cyclo (Tyr–D‐Cys–Phe–Cys–NH2), constrained by means of anS4.2S4.4disulfide between Cys2and Cys4; its twocisandtransC4.2C4.4‐olefinic dicarba analogs, and the product of saturation of them both. They are potent nonselective or moderately µ‐selective opioid agonistsin vitro.They have been synthesized and tested earlier [Berezowska I, Chung NN, Lemieux C, Wilkes BC, and Schiller PW, Acta Biochim Polon 53, 2006, 73–76]. We have studied their conformations using NMR and molecular dynamics. With major conformational constraints imposed by the 11‐membered ring spanning residues 2–4, they show well defined conformations of this ring, while the exocylic Tyr1and Phe3side chains still have significant conformational freedom. The more active and selective µversusδ disulfide and saturated dicarba agonists seem to have in common: (i) their ring structures more flexilble than those of the other two and (ii) their ring structures similar to each other and more diverse than those in the other two. Given this and the small size of the peptides having confirmed bioactivity profiles, there is a chance that their conformations determined in solution approach re

ISSN:1075-2617    

DOI:10.1002/psc.1022

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe chemical synthesis by solid‐phase methods of a novel amphiphilic peptide, peptide‐conjugate amphiphile (PCA), containing in the same molecule three different functions: (i) theN,N‐bis[2‐[bis(carboxy‐ethyl)amino]ethyl]‐L‐glutamic acid (DTPAGlu) chelating agent, (ii) the CCK8 bioactive peptide, and (iii) a hydrophobic moiety containing four alkyl chains with 18 carbon atoms each, is reported. In water solution at pH 7.4, PCA self‐assembles in very stable micelles at very low concentration [critical micellar concentration (cmc) values of 5 × 10−7mol kg−1] as confirmed by fluorescence spectroscopy. The structural characterization, obtained with small‐angle neutron scattering (SANS) measurements, indicates that the aggregates are substantially represented by ellipsoidal micelles with an aggregation number of 39 ± 2 and the two micellar axes of about 52 and 26 Å. Copyright © 2008 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.1024

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractWith only 14 amino acid residues, the trypsin inhibitor SFTI‐1 is the smallest naturally occurring serine proteinase inhibitor. It consists of two cyclic fragments (with head‐to‐tail cyclization and a disulfide bridge). In our previous paper, we showed that the removal of the disulfide bridge produced 2.4‐fold lower activity. Here, we present the total conformational analysis of the [Abu3, 11]‐SFTI‐1 analog by means of 2D NMR spectroscopy in conjunction with theoretical methods. The peptide was synthesized by Fmoc SPPS. It was cyclized with PyBop and DIPEA in DMF. The NMR studies were performed in DMSO‐d6at 303 K. Conformations of the peptide studied were calculated by the following three approaches: distance geometry (DG), molecular dynamics (MD) and determination of the statistical weights of conformations. The first two algorithms use a CHARMM force field, whereas the last uses an ECEPP/3 force field. Our calculations resulted in three sets of conformers with 7, 9 and 6 representatives, respectively. All our results were compared with published ones. It was found that the peptide has an ill‐defined structure. Despite its conformational flexibility, the binding loop (3–11 fragment) displayed geometry similar to the corresponding fragments of the other SFTI‐1 analogs and to the inhibitor itself. Furthermore, the peptide bond between the Ile7 and Pro8 residues adoptscisgeometry, which is essential for inhibitory activity. Copyright © 2008 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.1025

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractCombinatorial chemistry approach was applied to design chromogenic substrates of human β‐tryptase. The most active substrate, Ala‐Ala‐Pro‐Ile‐Arg‐Asn‐Lys‐ANB‐NH2, was selected from among over 9 million heptapeptides. The amide of 5‐amino‐2‐nitrobenzoic acid (ANB‐NH2) attached at theC‐terminus served as a chromophore. In order to determine the optimal length of the tryptase substrate, a series ofN‐terminally truncated fragments of this substrate was synthesized. Pro‐Ile‐Arg‐Asn‐Lys‐ANB‐NH2, with the determined value of the specificity constant (kcat/KM) above 9 × 106M−1s−1, appeared to be the most specific substrate of tryptase. This substrate was twice as active as the parent heptapeptide substrate. We postulate that the optimal size of the pentapeptide substrate for the interaction with human β‐tryptase is associated with the unique structure of this proteinase, comprising four almost identical monomer subunits arranged in a square flat ring with its substrate pockets faced inside, forming a tetramer with a central pore that can be penetrated by this short peptide. Copyright © 200

ISSN:1075-2617    

DOI:10.1002/psc.1026

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe arginine‐rich motif is a class of short arginine‐rich peptides that bind to specific RNA structures that has been found to be a versatile framework for the design and selection of RNA‐binding peptides. We previously identified novel peptides that bind to the Rev‐response element (RRE) RNA of the HIV from an arginine‐rich polypeptide library (ARPL) consisting of a polyarginine (15 mer) randomized at theN‐terminal 10 positions. The selected peptides bound more strongly to the RRE than the natural binding partner, Rev, and contained glutamine residues that were assumed to be important for recognition of the G–A base pair. In addition, the peptides were predicted to bind to the RRE in an α‐helical conformation. In this study, in order to understand the mechanism of the interaction between the RRE and the putative α‐helical glutamine‐containing peptides, the amino acid requirements for high affinity binding were analyzed by a combinatorial approach using a bacterial system for detecting RNA–peptide interactions. A consensus peptide, the DLA peptide, was elucidated, which consists of a single glutamine residue within a polyarginine context with the glutamine residue flanked at specific positions by three nonarginine residues, two of which appear to be important for α‐helix stabilization. In addition, the DLA peptide was found to bind extremely tightly to the RRE with an affinity 50‐fold higher than that of the Rev peptide as determined by a gel shift assay. A working model for the interaction of the DLA peptide to the RRE is proposed, which should aid in the development of peptide‐based drugs that inhibit HIV replication, as well as in our understanding of polypeptide–RNA interactions. Copyright © 2008 European Peptide

ISSN:1075-2617    

DOI:10.1002/psc.1027

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe formation of glycation products in model systems consisting of fructose and the endogenous opioid peptides not containing lysine residue, such as Leu‐enkephalin (Tyr‐Gly‐Gly‐Phe‐Leu) and Met‐enkephalin (Tyr‐Gly‐Gly‐Phe‐Met), or of their fragments, Tyr‐Gly‐Gly‐Phe and Tyr‐Gly‐Gly, was examined.N‐(2‐Deoxy‐aldos‐2‐yl)‐peptides (Heyns compounds) as well as diastereoisomeric imidazolidinone compounds were identified as reaction products ofN‐terminal amino group glycation for each of the peptides studied. The structure of the glycation products and relative configuration of C‐2 substituents on the imidazolidinone ring in diastereoisomers were determined by NMR experiments. The chemical and enzymatic stability of the fructose‐derived glycated products of Leu‐ and Met‐enkephalin was studied in phosphate‐buffered saline (pH 7.4) and in human serum at 37 °C. The obtained results revealed that glycation increases the stability of the parent peptide to enzymatic degradation. As a result of different configuration at the newly formed stereogenic center, large stability differences in the 2S* and 2R* isomers of the imidazolidinone compounds were observed. Copyright ©

ISSN:1075-2617    

DOI:10.1002/psc.1029

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractPeptide leadsD‐Phe–Pro–Arg for thrombin inhibition and Arg–Gly–Asp for antagonistic activity on fibrinogen receptor were combined in one molecule in order to produce compounds capable of acting both as thrombin inhibitors and as fibrinogen receptor antagonists. Peptide conjugate7possessing both leads joined by a tetraglycine linker as well as tripeptides and peptidomimetics with highly overlappedD‐Phe–Pro–Arg and Arg–Gly–Asp pharmacophore groups were prepared. Conjugate7was found to possess antagonistic activity on fibrinogen receptor, but was unexpectedly inactive as thrombin inhibitor. Compound9comprising of highly integratedD‐Phe–Pro–Arg and Arg–Gly–Asp pharmacophore groups was found to possess a moderate but well balanced thrombin inhibitory and fibrinogen receptor antagonistic activity. Copyright © 2008 European Peptide So

ISSN:1075-2617    

DOI:10.1002/psc.1030

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY

摘要:

AbstractThe proapoptotic influenza A virus PB1‐F2 protein contributes to viral pathogenicity and is present in most human and avian isolates. Previous synthetic protocols have been improved to provide a synthetic full length H1N1 type PB1‐F2 protein that is encoded by the ‘Spanish flu’ isolate and an equivalent protein from an avian host that is representative of a highly pathogenic H5N1 ‘bird flu’ isolate, termed SF2 and BF2, respectively. Full length SF2, different mutants of BF2 and a number of fragments of these peptides have been synthesized by either the standard solid‐phase peptide synthesis method or by native chemical ligation of unprotectedN‐ andC‐terminal peptide fragments. For SF2 chemical ligation made use of the histidine and the cysteine residues located in positions 41 and 42 of the native sequence, respectively, to afford a highly efficient synthesis of SF2 compared to the standard SPPS elongation method. By‐product formation at the aspartic acid residue in position 23 was prevented by specific modifications of the SPPS protocol. As the native sequence of BF2 does not contain a cysteine residue two different mutants of BF2 (Y42C) and BF2 (S47C) with appropriate cysteine exchanges were produced. In addition to the full length molecules, fragments of the native sequences were synthesized for comparison of their physical characteristics with those from the H1N1 human isolate A/Puerto Rico/8/34 (H1N1). All peptides were analyzed by mass spectrometry,1H NMR spectroscopy, and SDS‐PAGE. The protocols allow the synthesis of significant amounts of PB1‐F2 and its related peptides. Copyright © 2008 European Peptide Society

ISSN:1075-2617    

DOI:10.1002/psc.1031

出版商:John Wiley&Sons, Ltd.    

年代:2008

数据来源: WILEY