TY - JOUR
T1 - Hydrophobicity drives the cellular uptake of short cationic peptide ligands
AU - Gupta, Anju
AU - Mandal, Deendayal
AU - Ahmadibeni, Yousef
AU - Parang, Keykavous
AU - Bothun, Geoffrey
PY - 2011/6
Y1 - 2011/6
N2 - Short cationic linear peptide analogs (LPAs, prepared as Arg-C n -Arg-C n -Lys, where C n represents an alkyl linkage with n = 4, 7 or 11) were synthesized and tested in human breast carcinoma BT-20 and CCRF-CEM leukemia cells for their application as targeting ligands. With constant LPA charge (+4), increasing the alkyl linkage increases the hydrophobic/hydrophilic balance and provides a systematic means of examining combined electrostatic and hydrophobic peptide-membrane interactions. Fluorescently conjugated LPA-C11 (F-LPA-C11) demonstrated significant uptake, whereas there was negligible uptake of the shorter LPAs. By varying temperature (4°C and 37°C) and cell type, the results suggest that LPA-C11 internalization is nonendocytic and nonspecific. The effect of LPA binding on the phase behavior, structure, and permeability of model membranes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine (DPPC/DPPS, 85/15) was studied using differential scanning calorimetry (DSC), cryogenic transmission electron microscopy (cryo-TEM), and fluorescence leakage studies to gain insight into the LPA uptake mechanism. While all LPAs led to phase separation, LPA-C11, possessing the longest alkyl linkage, was able to penetrate into the bilayer and caused holes to form, which led to membrane disintegration. This was confirmed by rapid and complete dye release by LPA-C11. We propose that LPA-C11 achieves uptake by anchoring to the membrane via hydrophobicity and forming transient membrane voids. LPAs may be advantageous as drug transporter ligands because they are small, water soluble, and easy to prepare.
AB - Short cationic linear peptide analogs (LPAs, prepared as Arg-C n -Arg-C n -Lys, where C n represents an alkyl linkage with n = 4, 7 or 11) were synthesized and tested in human breast carcinoma BT-20 and CCRF-CEM leukemia cells for their application as targeting ligands. With constant LPA charge (+4), increasing the alkyl linkage increases the hydrophobic/hydrophilic balance and provides a systematic means of examining combined electrostatic and hydrophobic peptide-membrane interactions. Fluorescently conjugated LPA-C11 (F-LPA-C11) demonstrated significant uptake, whereas there was negligible uptake of the shorter LPAs. By varying temperature (4°C and 37°C) and cell type, the results suggest that LPA-C11 internalization is nonendocytic and nonspecific. The effect of LPA binding on the phase behavior, structure, and permeability of model membranes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine (DPPC/DPPS, 85/15) was studied using differential scanning calorimetry (DSC), cryogenic transmission electron microscopy (cryo-TEM), and fluorescence leakage studies to gain insight into the LPA uptake mechanism. While all LPAs led to phase separation, LPA-C11, possessing the longest alkyl linkage, was able to penetrate into the bilayer and caused holes to form, which led to membrane disintegration. This was confirmed by rapid and complete dye release by LPA-C11. We propose that LPA-C11 achieves uptake by anchoring to the membrane via hydrophobicity and forming transient membrane voids. LPAs may be advantageous as drug transporter ligands because they are small, water soluble, and easy to prepare.
KW - Calorimetry
KW - Cell-penetrating peptide
KW - Lipid membrane
KW - Phase separation
KW - Pore formation
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U2 - 10.1007/s00249-011-0685-4
DO - 10.1007/s00249-011-0685-4
M3 - Article
C2 - 21409455
AN - SCOPUS:79956129441
SN - 0175-7571
VL - 40
SP - 727
EP - 736
JO - European Biophysics Journal
JF - European Biophysics Journal
IS - 6
ER -