Poly-L-lysines and poly-L-arginines induce leakage of negatively charged phospholipid vesicles and translocate through the lipid bilayer upon electrostatic binding to the membrane
2009 (English)In: Biophysical Chemistry, ISSN 0301-4622, E-ISSN 1873-4200, Vol. 144, no 1-2, 27-37 p.Article in journal (Refereed) Published
Poly-lysines (PLL) and poly-arginines (PLA) of different polymer chain lengths interact strongly with neg. charged phospholipid vesicles mainly due to their different elec. charges. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) and their mixts. (1/1 mol/mol) with the resp. phosphatidylcholines of equiv. chain length were chosen as model membrane systems that form at room temp. either the fluid Lalpha or the gel phase Lbeta lipid bilayer membranes, resp. Leakage expts. revealed that the fluid POPG membranes are more perturbed compared to the gel phase DPPG membranes upon peptide binding. Furthermore, it was found that pure PG membranes are more prone to release the vesicle contents as a result of pore formation than the lipid mixts. POPG/POPC and DPPG/DPPC. For the longer polymers (>= 44 amino acids) maximal dye-release was obsd. when the molar ratio of the concns. of amino acid residues to charged lipid mols. reached a value of R P = 0.5, i.e. when the outer membrane layer was theor. entirely covered by the polymer. At ratios lower or higher than 0.5 leakage dropped significantly. Furthermore, PLL and PLA insertions and/or translocations through lipid membranes were analyzed by using FITC-labeled polymers by monitoring their fluorescence intensity upon membrane binding. Short PLL mols. and PLA mols. of all lengths seemed to translocate through both fluid and gel phase lipid bilayers. Comparison of the PLL and PLA fluorescence assay results showed that PLA interacts stronger with phospholipid membranes compared to PLL. Isothermal titrn. calorimetry (ITC) measurements were performed to give further insight into these mechanisms and to support the findings obtained by fluorescence assays. Cryo-transmission electron microscopy (cryo-TEM) was used to visualize changes in the vesicles' morphol. after addn. of the polypeptides.
Place, publisher, year, edition, pages
2009. Vol. 144, no 1-2, 27-37 p.
Phospholipid membranes, Cationic polypeptides, Peptide-lipid interactions, Dye-release assay
Research subject Physical Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-107554DOI: 10.1016/j.bpc.2009.06.002ISI: 000269179200004OAI: oai:DiVA.org:uu-107554DiVA: diva2:231695