Product
name: combi-2
Sequence:
Ac-FRWWHR-NH2
Modifications: N-terminal
acetylation,C-terminal amide,
Purity: 95% by
HPLC
Counter
ion: Trifluoacetate
Format: Lyophilized
powder
Description: The acetylated and amidated
hexapeptide FRWWHR (combi-2), previously identified by combinatorial chemistry
methods, shows strong antimicrobial activity. The binding of the peptide to
1-palmitoyl-2-oleoyl-sn-glycero-3-[(phospho-rac-(1-glycerol)] (POPG) and
1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) vesicles was studied
using fluorescence spectroscopy and isothermal titration calorimetry (ITC).
Differential scanning calorimetry (DSC) with dipalmitoylphosphatidylcholine
(DPPC) and dipalmitoylphosphatidylglycerol (DPPG) multilamellar vesicles was
performed to determine changes in the lipid phase behaviour upon binding the
peptide. Two-dimensional proton nuclear magnetic resonance (NMR) spectroscopy,
to solve the bound peptide structure, was performed in the presence of
dodecylphosphatidylcholine (DPC) and sodium dodecyl sulphate (SDS) micelles. The
fluorescence, ITC and DSC studies indicate that the peptide interacts
preferentially with lipid vesicles containing negatively charged head groups.
Conformational information determined using NMR indicate that the combi-2
peptide adopts a coiled amphipathic conformation when bound to SDS and DPC
micelles. Leakage assays indicate that the peptide is not very efficient at
causing leakage from calcein-filled large unilamellar vesicles comprised of
POPG/POPC (1 : 1). The rapid passage of either the fluorescent-tagged peptides
combi-2 or the previously studied peptide Ac-RRWWRF-NH(2) (combi-1) into
Escherichia coli and Staphylococcus aureus suggests that instead of membrane
disruption, the main bactericidal site of action of these peptides might be
located inside bacteria.
Usage: For
Scientific Research Use Only, Not for Human Use.
Reference:
J Pept Res.
2005 May;65(5):491-501.