Conformation of a novel tetrapeptide inhibitor NH2-D-Trp-D-Met-Phe(pCl)-Gla-NH2 bound to farnesyl-protein transferase

Characterization and NMR solution structure of a novel cyclic pentapeptide inhibitor of pathogenic hantaviruses

Hantavirus-induced diseases such as hantavirus cardiopulmonary syndrome and hemorrhagic fever with renal syndrome are a global health concern. Hantavirus cardiopulmonary syndrome caused by Sin Nombre virus lacks specific therapy and its high mortality makes Sin Nombre virus a potential bioweapon agent. Sin Nombre virus entry into susceptible cells requires expression of alpha(v)beta(3) integrin. We recently reported the sequence of a cyclic nonapeptide that inhibited Sin Nombre virus entry into Vero E6 cells at a level comparable to ReoPro, a Fab fragment of the anti-beta(3) antibody c7E3. Here, we refine the parental peptide, cyclo-[CPFVKTQLC], using alanine scanning and amino acid deletions, by optimizing for viral inhibition. The IC(50) of the resulting peptide, cyclo-[CPFVC], was 267 microM compared with 263 microM for the parental peptide. The solution structure of cyclo-[CPFVC] was determined by two-dimensional nuclear magnetic resonance spectroscopy, revealing the Phe ring in an extended conformation stacked against the Pro ring and containing a beta-turn encompassing Val-4 through Cys-1. As an initial step in identifying interactions between cyclo-[CPFVC] and its target cellular receptor, the refined peptide structure was docked into the ReoPro binding site of integrin beta(3). This structure will provide the basis for designing more potent peptidomimetic therapeutics to prevent Sin Nombre virus entry and treat hantavirus cardiopulmonary syndrome.

A combinatorial approach toward the generation of ambiphilic peptide-based inhibitors of protein:geranylgeranyl transferase-1

A combinatorial synthesis of oligopeptide analogues and their evaluation as protein:geranylgeranyl transferase inhibitors is presented. The combinatorial strategy is based on the random mutation, in each new generation, of one of any of the four amino acid building blocks of which the most effective compounds of the previous generation are assembled. In this way, a progressive improvement of the average inhibitory activity was observed until the fifth generation. The most active inhibitors were found to inhibit PGGT-1 in the low micromolar range (IC(50): 3.8-8.1 microM).

NMR-derived model of interconverting conformations of an ICAM-1 inhibitory cyclic nonapeptide

We have produced by phage-display a disulfide-linked cyclic nonapeptide (inhibitory peptide-01, IP01), CLLRMRSIC, that binds to intracellular adhesion molecule-1 (ICAM-1) and blocks binding to its counter-structure, leukocyte functional antigen-1 (LFA-1). As a first step towards improving its pharmacologic properties, we have performed a structural and functional analysis of this peptide inhibitor to determine the features relevant to ICAM-1 binding. We report here the solution model of our initial product, IP01, as derived from two-dimensional nuclear magnetic resonance (NMR) restraints and molecular modeling. Distance and dihedral angle restraints, generated from nuclear Overhauser effect spectroscopy (NOESY) and one-dimensional-NMR experiments respectively, were used to generate an ensemble of structures using distance geometry and simulated annealing. Molecular dynamic simulations produced three interconverting conformational families consistent with the NMR-derived constraints. We describe these conformations and their mechanism of interconversion. Furthermore, we have measured the IC50 s of a series of inhibitors generated from IP01 through alanine substitution of each residue. These results show that the L2-L3-R4-M5-R6 segment is functionally active, conformationally flexible, and contains a beta-turn involving residues R4-S7, while the C1-C9-I8-S7 segment is less functionally-active but adopts a more defined solution conformation, consistent with a scaffolding function. This model will be useful for designing nonpeptide-based organic inhibitors with improved pharmacologic properties.

Peptides with anticancer use or potential

This review is an attempt to illustrate the diversity of peptides reported for a potential or an established use in cancer therapy. With 612 references, this work aims at covering the patents and publications up to year 2000 with many inroads in years 2001-2002. The peptides are classed according to four categories of effective (or plausible) biological mechanisms of action: receptor-interacting compounds; inhibitors of protein-protein interaction; enzymes inhibitors; nucleic acid-interacting compounds. The fifth group is made of the peptides for which no mechanism of action has been found yet. Incidentally this work provides an overview of many of the modern targets of anticancer research.

A biaryl peptide crosslink in a MetJ peptide model confers cooperative, nonspecific binding to DNA that ablates both repressor binding and in vitro transcription

The MetJ repressor is the archetypal example of the beta-ribbon-helix-helix DNA binding motif. A model of the MetJ beta-ribbon (residues 22-28) was prepared by forming a dityrosine crosslinked dimer from the heptapeptide KKYTVSI. Using SPR, the peptide dimer 2 was shown to bind to dsDNA under physiologically relevant conditions, whereas the monomeric peptide did not. The peptide dimer appeared to inhibit binding of the MetJ repressor to natural met operators. Based on the stoichiometry of binding, the binding of peptide dimer 2 seems both highly co-operative and to lack sequence specificity. Peptide binding also appears to prevent transcription in vitro.