In the picture: disulfide-poor conopeptides, a class of pharmacologically interesting compounds

During evolution, nature has embraced different strategies for species to survive. One strategy, applied by predators as diverse as snakes, scorpions, sea anemones and cone snails, is using venom to immobilize or kill a prey. This venom offers a unique and extensive source of chemical diversity as it is driven by the evolutionary pressure to improve prey capture and/or to protect their species. Cone snail venom is an example of the remarkable diversity in pharmacologically active small peptides that venoms can consist of. These venom peptides, called conopeptides, are classified into two main groups based on the number of cysteine residues, namely disulfide-rich and disulfide-poor conopeptides. Since disulfide-poor conotoxins are minor components of this venom cocktail, the number of identified peptides and the characterization of these peptides is far outclassed by its cysteine-rich equivalents. This review provides an overview of 12 families of disulfide-poor peptides identified to date as well as the state of affairs.

Apoptosis induced by (di-isopropyloxyphoryl-Trp)2-Lys-OCH3 in K562 and HeLa cells.

According to the method used in our laboratory,our group synthesized (DIPP-Trp)2-Lys-OCH 3. It inhibited the proliferation of K562 and HeLa cells in a dose-and time-dependent manner with an IC 50 of 15.12 and 42.23 microM, respectively. (DIPP-Trp) 2-Lys-OCH3 induced a dose-dependent increase of the G2/M cell population in K562 cells, and S cell population in HeLa cells;the sub-G0 population increased dramatically in both cell lines as seen by PI staining experiments using a FACS Calibur Flow cytometer (BeckmanCoulter,USA). Phosphatidylserine could signi?cantly translocate to the surface of the membrane in (DIPP-Trp)2-Lys-OCH3-treated K562 and HeLa cells.The increase of an early apoptotic population was observed in a dose-dependent manner by both annexin-FITC and PI staining.It was concluded that (DIPP-Trp) 2-Lys-OCH3 not only induced cells to enter into apoptosis,but also affected the progress of the cell cycle.It may have arrested the K562 and HeLa cells in the G 2/M,S phases,respectively.The apoptotic pathway was pulsed at this point,resulting in the treated cells entering into programmed cell death.(DIPP- Trp)-Lys-OCH is a potential anticancer drug that intervenes in the signalling pathway.

Anti-HER2/neu Peptide Producing Vector System for Biologic Therapy - Is It Possible to Mass-produce the Peptide?

A humanized monoclonal antibody against HER2 has been using in a clinical setting and has been shown to possess therapeutic properties. A mimetic peptide against HER2 was also reported to bind to the HER2 receptor with some therapeutic potential. Based on a previous report and the sequence of Herceptin, we designed oligonucleotides of anti-HER2 mimetic peptides, named V2 and V3 peptides, in order to develop a peptide- producing vector system for biologic therapy against HER2- overexpressing cancers. We also adopted the sequence of a previously reported mimetic peptide, V1 (Park BW et al. Nat. Biotechnol, 2000, 18: 194-198), as a reference peptide. We examined the effects of the V2 and V3 peptides against the HER2-overexpressing cell lines, SK-BR-3 and T6-17. Transient transfection of the construct expressing V1 and V2 inhibited cell proliferation in HER2-overexpressing cell lines by 20 - 30%, but had no effect on the HER2-negative NIH3T3 cells. The proliferation inhibition shown by V2 was slightly better than that shown by V1. Recombinant peptides V2 and V3 were produced on a large scale in an E. coli system, and the V2 peptide showed anti-HER2-specific tumor cell proliferation inhibition of 10% to 30%. Current results suggest that anti-HER2 mimetic peptides, overexpressed by a constitutive promoter or produced in an E. coli system, could specifically inhibit the proliferation of HER2-expressing cancer cells. Further efforts to augment the biologic specificity and efficacy and to develop new technologies for the purification of the peptide from the E coli system are needed.

Insight into the environment of tryptophan in a hydrophobic model peptide upon aggregation and interaction with lipid vesicles: a steady state and time resolved fluorescence study.

Fluorescence spectroscopy is extensively used to monitor binding of peptides to lipid vesicles as well as orientation in the lipid bilayer. In steady-state fluorescence, the emission characteristics of intrinsic and extrinsic fluorophores, which are sensitive to environment are monitored. Life time measurements should yield useful information about the location and flexibility of fluorophores, as these factors have a significant effect on the life times. However, studies on protein structure and dynamics indicate that interpretation of life-time data is complicated (Beechem. J.M. and Brand, L. (1985) Annu. Rev. Biochem. 54, 43-71). Hence, simple well-defined systems should help in interpretation of life time data, especially in lipid-peptide interactions. In order to examine how fluorescence characteristics of tryptophan and anthroyl group would reflect molecular details of peptide aggregation and lipid-peptide interaction, studies have been carried out on a model hydrophobic peptide and its fatty acylated derivative. Steady-state fluorescence measurements suggest that: (1) the fatty acyl chain attached to an amino acid associates with the peptide chain in aqueous environment. (2) In the lipid bilayer, the acyl chain is oriented perpendicular to the lipid bilayer surface with the peptide chain at an angle to it. Analysis of the fluorescence decay of tryptophan indicates the predominance of a very short life-time component (<1ns) in aqueous environment and lipid-vesicles. Since the preexponentials were not negative, it is unlikely that this is due to extensive deactivation process. We attribute the observation of the low life time component to predominance of one rotamer around (C alpha-C beta)bond of tryptophan in aqueous and lipid environments. Our investigations suggest that fluorescence life time data need to be complemented with steady state measurements to get an insight into details of lipid-peptide interaction.

Synthetic peptides related to the delta-receptor agonist, dermorphin gene associated peptide.

The delta-receptor selective dermorphin gen associated peptide (DGAP) and five of its analogues having structural modifications at positions 2, 4 and 5 were synthesized by the solid phase method using 9-fluorenylmethoxycarbonyl amino acid trichlorophenyl esters as coupling agents and rho-benzyloxybenzyl alcohol resin as the solid support. The delta-receptor selectivity of these peptides was determined by guinea pig ileum and mouse vas deferens assays. The latter assay was carried out using modified Kreb's solution aerated with pure oxygen instead of carbogen. All the synthetic peptides were found to be delta-receptor selective.