A series of peptides derived from three domains within the fusion protein of Sendai virus was synthesized and examined for their potential to inhibit the fusion of the virus with human red blood cells. These domains include the ‘fusion peptide’ and two heptad repeats, one adjacent to the fusion peptide (SV‐163) and the other to the transmembrane domain (SV‐473). Of all the peptides tested, only SV‐473 was highly inhibitive. Using fluorescently‐labelled peptides, the mechanism through which the SV‐473 peptide inhibits the haemolytic activity of the virus was investigated. The results suggest that interactions of the active peptide with virion elements and lipid membranes are involved. Since it has recently been found that synthetic peptides corresponding to putative coiled‐coil domains of the human immunodeficiency virus (HIV) type 1 transmembrane protein gp41 are potent inhibitors of HIV, we discuss the general property of virus‐derived coiled‐coil peptides as inhibitors of viral infection.

An increasing body of evidence indicates that accumulation of soluble oligomeric assemblies of β-amyloid polypeptide (Aβ) play a key role in Alzheimer's disease (AD) pathology. Specifically, 56 kDa oligomeric species were shown to be correlated with impaired cognitive function in AD model mice. Several reports have documented the inhibition of Aβ plaque formation by compounds from natural sources. Yet, evidence for the ability of common edible elements to modulate Aβ oligomerization remains an unmet challenge. Here we identify a natural substance, based on cinnamon extract (CEppt), which markedly inhibits the formation of toxic Aβ oligomers and prevents the toxicity of Aβ on neuronal PC12 cells. When administered to an AD fly model, CEppt rectified their reduced longevity, fully recovered their locomotion defects and totally abolished tetrameric species of Aβ in their brain. Furthermore, oral administration of CEppt to an aggressive AD transgenic mice model led to marked decrease in 56 kDa Aβ oligomers, reduction of plaques and improvement in cognitive behavior. Our results present a novel prophylactic approach for inhibition of toxic oligomeric Aβ species formation in AD through the utilization of a compound that is currently in use in human diet.

The ligand binding site of the nicotinic acetylcholine receptor (AcChoR) is within a short peptide from the a subunit that includes the tandem cysteine residues at positions 192 and 193. To elucidate the molecular basis of the binding properties of the AcChoR, we chose to study nonclassical muscle AcChoRs from animals that are resistant to a-neurotoxins. We have previously reported that the resistance of snake AcChoR to a-bungarotoxin (a-BTX) may be accounted for by several major substitutions in the ligand binding site of the receptor. In the present study, we have analyzed the binding site of AcChoR from the mongoose, which is also resistant to a-neurotoxins. It was shown that mongoose AcChoR does not bind a-BTX in vivo or in vitro. cDNA fragments of the a subunit of mongoose AcChoR corresponding to codons 122-205 and including the presumed ligand binding site were cloned, sequenced, and expressed in Escherichia coi. The expressed protein agments of the mongoose, as well as of snake receptors, do not bind a-BTX. The mongoose fragment is highly homologous (>90%) to the respective mouse fragment. Out of the seven amino acid differences between the mongoose and mouse in this region, five cluster in the presumed ligand big site, close to cysteines 192 and 193. These changesare at positions 187 (Trp -Asn), 189 (Phe Thr), 191

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The ligand binding site of the nicotinic acetylcholine receptor (AChR) is located in the alpha-subunit, within a small fragment containing the tandem cysteines at positions 192 and 193. We have been analyzing the binding site domain of AChRs from several animal species exhibiting various degrees of resistance to alpha-bungarotoxin (alpha-BTX). Our earlier work on the snake and mongoose AChR, both of which do not bind alpha-BTX, suggested that amino acid substitutions at positions 187, 189, and 194 of the AChR alpha-subunit are important in determining the resistance of these AChRs to alpha-BTX. In the present study, we have examined the correlation between alpha-BTX binding and the structure of the binding site domain of AChR from the hedgehog, shrew, cat, and human. Fragments of the AChR alpha-subunit corresponding to residues 122-205 from these species were cloned, sequenced, and expressed in Escherichia coli. The hedgehog fragment does not bind alpha-BTX, in common with the snake and mongoose AChR, and the human fragment is a partial binder. The shrew and cat fragments bind alpha-BTX to a similar extent as the mouse fragment. The hedgehog and human AChRs have nonaromatic amino acid residues at positions 187 and 189 of the alpha-subunit, as is seen with the "toxin resistant" snake and mongoose, and in contrast with the "toxin binders", which have aromatic residues at these two positions.(ABSTRACT TRUNCATED AT 250 WORDS)

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Abstract. The effectiveness of the chelating agent CaNa 2 EDTA and the peptidomimetic matrix metalloproteinase inhibitor batimastat (BB-94) to inhibit local tissue damage induced by Bothrops asper snake venom was studied in mice. Both compounds totally inhibited proteolytic, hemorrhagic, and dermonecrotic effects, and partially reduced edema-forming activity, when incubated with venom prior to injection. Much lower concentrations of batimastat than of CaNa 2 EDTA were required to inhibit these effects. In addition, batimastat, but not CaNa 2 EDTA, partially reduced myotoxic activity of the venom. When the inhibitors were administered at various time intervals after envenomation at the same site of venom injection, both compounds were effective in neutralizing local hemorrhage and dermonecrosis if administered rapidly after venom. Inhibition was not as effective as the time lapse between venom and inhibitor injections increased. Owing to the relevance of metalloproteinases in the pathogenesis of local tissue damage induced by B. asper and other pit viper venoms, it is suggested that administration of peptidomimetic metalloproteinase inhibitors or CaNa 2 EDTA at the site of venom injection may represent a useful alternative to complement antivenoms in the neutralization of venom-induced local tissue damage.

We have detected a leucine zipper-like motif in the ectodomain of the Sendai virus fusion protein (aa 269-307) which is extremely conserved in the family of Sendai viruses. To find a possible role for this motif, we synthesized SV-269, a 39 amino acid peptide corresponding to this domain, and a mutant peptide, MuSV-269, with an amino acid pair interchanged their positions. The peptides were labeled with fluorescent probes at their N-terminal amino acid and functionally and structurally characterized. The data show that SV-269, but not MuSV-269, specifically binds Sendai virus. Expectedly, SV-269 is more active than the mutant MuSV-269 in inhibiting Sendai virus-mediated hemolysis. Fluorescence studies reveal that SV-269 assembles in aqueous solution, binds to zwitterionic PC and negatively-charged PS/PC vesicles, and assembles therein. Although MuSV-269 similarly binds to both types of vesicles, it only slightly assembles in solution and not at all in membranes. Moreover, SV-269, but not MuSV-269, coassembles with the biologically-active heptad repeats SV-150 and SV-473 (Rapaport et al. , 1995) in solution as revealed by fluorescence and circular dichroism (CD) spectroscopy, and with SV-150 within negatively-charged PS/PC and zwitterionic PC vesicles. Despite these differences, both SV-269 and MuSV-269 adopt similar secondary structures in 40% TFE and 1% SDS as revealed by CD spectroscopy, and disrupt the packing of the lipid bilayers to the same extent, as shown by the dissipation of diffusion potential. The role of this leucine zipper motif is discussed in terms of the assembly of the Sendai virus fusion protein in solution and within membranes. Since most of the heptadic leucines are also conserved in the corresponding domains of other paramyxoviruses such as rinderpest, measles, SV5, and parainfluenza, it may indicate a similar role of this domain in these viruses as well.