摘要:

AbstractA new linear gramicidin analog bearing a biotinyl group grafted on C‐terminal part was designed to study ligand–receptor interactions. The C‐terminal alcohol in the native peptide was first replaced by an amino group. Then the peptide was synthesized on a polystyrene resin functionalized by the 2‐chlorotrityl chloride following a biotinylation performed in solution. This newN′‐biotinyl‐(EDA)15‐Gramicidin A was reconstituted in planar lipid bilayers and exhibited channel activities similar to those of natural gramicidin, with unitary conductance value about 30 ps in 1mKCl. Furthermore this ionophore activity was quenched by addition of streptavidin in the surrounding medium. Our system is an outstanding tool for monitoring ligand–receptor interactions and could be used for designing a new biosensor. © 1998 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199809)4:6<371::AID-PSC156>3.0.CO;2-Z

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractHigh‐affinity ligands of non‐peptidic nature, binding to the class I major histocompatibility complex protein HLA B*2705 whose expression is strongly linked to the pathogenesis of the autoimmune disease ankylosing spondylitis, should give way to a selective immunotherapy by blocking or antagonising the interaction with autoreactive T cell clones. Here we present experimental data on the binding of modified peptides, designed to optimally bind to HLA‐B*2705 by filling a hydrophobic binding pocket (pocket D) with nonencoded aromatic amino acids. Three peptides with altered side chains (alpha‐naphthylalanine, beta‐naphthylalanine and homophenylalanine) in position 3 were synthesised. The thermal denaturation profiles of the HLA protein in complex with the modified peptides, monitored by circular dichroism spectroscopy, showed a significant shift towards higher melting temperatures with respect to the parent T cell epitope. The proposed binding mode of the nonnatural peptides was checked by site‐directed mutagenesis of the pocket D, hypothesised to accommodate the large hydrophobic side chains. Reducing the size and depth of the pocket by mutating Leu l56 into Trp only affects the binding of the non‐natural ligands, thus providing experimental evidence that the nonnatural peptide amino acids bind as predicted to the host MHC protein. © 1998 European Peptide Society and John W

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199809)4:6<378::AID-PSC157>3.0.CO;2-B

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractWe have synthesized by solution‐phase methods two analogues of the 11‐residue lipopeptaibol antibiotic trichogin GA IV in which the N‐terminaln‐octanoyl group is replaced either by an N‐acetylated 2‐amino‐2‐methyl‐l‐undecanoic acid or by an N‐acetylatedα‐aminoisobutyric acid. CD, FTIR absorption, and NMR analyses unequivocally show that the main structural features of trichogin GA IV are preserved in these analogues. Since only the peptide containing the lipophilic chain exhibits membrane‐modifying properties, these results strongly support the view that moving the long acyl moiety from the Nα‐blocking group to the side chain of the N‐terminal extra‐residue does not affect the conformational properties or the membrane activity of trichogin GA IV. © 1998 European Peptid

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199809)4:6<389::AID-PSC158>3.0.CO;2-4

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY

摘要:

AbstractOn the basis of our recent results, the N‐terminal sequence of HIV‐1 Tat protein as a natural competitive inhibitor of dipeptidyl peptidase IV (DP IV) is supposed to interact directly with the active site of DP IV hence mediating its immunosuppressive effects via specific DP IV interactions. Of special interest is the finding that amino acid substitutions of the Tat(1–9) peptide (MDPVDPNIE) in position 5 with S‐isoleucine and in position 6 with S‐leucine led to peptides with strongly reduced inhibitory activity suggesting differences in the solution conformation of the three analogues. Therefore,1H NMR techniques in conjunction with molecular modelling have been used here to determine the solution structure of Tat(1–9), I5‐Tat(1–9) and L6‐Tat(1–9) and to examine the influence of amino acid exchanges on structural features of these peptides. The defined structures revealed differences in the conformations what might be the reason for different interactions of these Tat(1–9) analogues with certain amino acids of the active site of DP IV. © 1998 European Peptide Society an

ISSN:1075-2617    

DOI:10.1002/(SICI)1099-1387(199809)4:6<400::AID-PSC162>3.0.CO;2-G

出版商:John Wiley&Sons, Ltd.    

年代:1998

数据来源: WILEY