摘要:

AbstractIn this paper, we describe the predominant conformational forms adopted by tripeptides and higher oligopeptides in aqueous solution. About 50 tripeptides and almost 20 higher oligopeptides (4–6 residues) were subjected to conformational analysis using SYBYL Random Search. As with dipeptides (Grail BM, Payne JW.J. Peptide Sci.2000;6:186–199), both tripeptides and higher oligopeptides were found to occupy relatively few combinations of psi–phi space that were distinct from those associated with predominant protein secondary structures (e.g. helices and β‐sheets). Again, the preferred psi (ψ) values for the first residue (i−1) were in sectors encompassed by the ranges from +150° to ±180°, +60° to +90° and −60° to −90°, which were combined with preferred phi (ϕ) values for the second residue (i) in sectors with ranges from −150° to ±180°, −60° to −90° and +30° to +60°. It was notable that tripeptides and, to a greater extent, higher oligopeptides adopted an initial psi (ψ) (Tor2) from +150° to ±180°. For tripeptides, theirN–Cdistances (distance betweenN‐terminal nitrogen andC‐terminal carbon atoms) distribute about 6.5 Å to give shorter, ‘folded’ conformers that are similar in length to dipeptides, and longer, ‘extended’ conformers that are distinct. Furthermore, for higher oligopeptides, theirN–Cdistances did not increment in relation to their increasing number of residues and short, ‘folded’ conformers were still present. These findings have a bearing upon the recognition of these molecules as substrates for widely distributed peptidases and peptide transporters. Copyr

ISSN:1075-2617    

DOI:10.1002/psc.312

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractBovine lactoferricin is a 25‐residue antibacterial peptide isolated after gastric cleavage of the iron transporting protein lactoferrin. A 15‐residue fragment, FKCRRWQWRMKKLGA of this peptide sustains most of the antibacterial activity. In this truncated sequence, the two Trp residues are found to be essential for antibacterial activity. The anchoring properties of Trp, as have been observed in membrane proteins, are believed to be important for the interaction of Trp containing antibacterial peptides with bacterial cell membranes. We have investigated the molecular properties which make Trp important for the antibacterial activity of the 15‐residue peptide by replacing Trp with natural and unnatural aromatic amino acids. This series of peptides was tested for antibacterial activity againstEcherichia coliandStaphylococcus aureus. We found that neither the hydrogen bonding ability nor the amphipathicity of the indole system are essential properties for the effect of Trp on the antibacterial activity of the peptides. Replacement of Trp with residues containing aromatic hydrocarbon side chains gave the most active peptides. We propose that aromatic hydrocarbon residues are able to position themselves deeper into the bacterial cell membrane, making the peptide more efficient in disrupting the bacterial cell membrane. From our results the size, shape and aromatic character of Trp seem to be the most important features for the activity of this class of Trp containing antibacterial peptides. Copyright © 2001 European Peptide Society and John Wiley&Son

ISSN:1075-2617    

DOI:10.1002/psc.318

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractPeptide T (ASTTTNYT), a fragment corresponding to residues 185–192 of gp120, the coat protein of HIV, is endowed with several biological propertiesin vitro, notably inhibition of the binding of both isolated gp120 and HIV‐1 to the CD4 receptor, and chemotactic activity. Based on previous nuclear magnetic resonance (NMR) studies performed in our laboratory, which were consistent with a regular conformation of theC‐terminal pentapeptide, and SAR studies showing that theC‐terminal pentapeptide retains most of the biological properties, we designed eight hexapeptides containing in the central part either the TNYT or the TTNY sequence, and charged residues (D/E/R) at the two ends. Conformational analysis based on NMR and torsion angle dynamics showed that all peptides assume folded conformations, albeit with different geometries and stabilities. In particular, peptides carrying an acidic residue at theN‐terminus and a basic residue at theC‐terminus are characterized by stable helical structures and retain full chemotactic activity. The solution conformation of peptide ETNYTR displays strong structural similarity to the region 19–26 of both bovine pancreatic and bovine seminal ribonuclease, which are endowed with anti‐HIV activity. Moreover, the frequent occurrence, in many viral proteins, of TNYT and TTNY, the two core sequences employed in the design of the hexapeptides studied in the present work, hints that the sequence of theC‐terminal pentapeptide TTNYT is probably representative of a widespread viral recognition motif. Copyright © 2001 European Peptide Society and Jo

ISSN:1075-2617    

DOI:10.1002/psc.320

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractRecent advances in the chemistry of fullerene have allowed the synthesis of many classes of novel fullerene derivatives. Among these classes, fullerene‐based amino acids and peptides are particularly interesting, both for structural studies and biological applications. In this review, we will discuss our own achievements in this rapidly growing field. In particular, the application of fulleroproline (Fpr) amino acids and peptides to medicinal chemistry and material science will be highlighted. Copyright © 2001 European Peptide Society and John Wiley&Sons, L

ISSN:1075-2617    

DOI:10.1002/psc.313

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY

摘要:

AbstractThe synthesis of an imidazoline dipeptide mimetic (a 4,5‐dihydroimidazole‐4‐carboxylic acid) is reported that displays an intramolecular hydrogen‐bond consistent with a turn conformation in solution. Copyright © 2001 European Peptide Society and John Wiley&S

ISSN:1075-2617    

DOI:10.1002/psc.319

出版商:John Wiley&Sons, Ltd.    

年代:2001

数据来源: WILEY