A novel amphipathic cell-penetrating peptide based on the N-terminal glycosaminoglycan binding region of human apolipoprotein E

Effect of hydrophobic moment on membrane interaction and cell penetration of apolipoprotein E-derived arginine-rich amphipathic α-helical peptides

“…4 b, the wavelength of maximum fluorescence (WMF) that reflects the change in Trp environment decreased with increased lipid/peptide weight ratio, wherein A2-17 L14R/R15L exhibited the largest decrease. Based on the one-site binding model 11 , we confirmed that the value of the dissociation constant K d for the binding of A2-17 L14R/R15L to EPC-SUVs was 1.4 ± 0.18 µM, which is comparable to that for the binding of A2-17 to EPC-SUVs ( K d = 1.1 ± 0.42 µM) 11 . The K d values of A2-17 R10L/L11R and A2-17 R7L/L8R were difficult to determine accurately because of small changes in their fluorescence spectra.…”

“…This indicates that A2-17 and A2-17 L14R/R15L have an amphipathic nature that allows it to bind to neutrally charged lipid membranes through non-electrostatic interactions between the membrane and the hydrophobic residues of the non-polar face of the α-helix (Fig. 1 ) required for the effective binding of ARPs to cellular lipid membranes 11 , 22 , 23 . In contrast, the α-helical conformation of the peptides, except for A2-17 L14R/R15L, was more enhanced upon the interaction with EPC/egg phosphatidylglycerol (EPG)-SUVs than with EPC-SUVs (Fig.…”

“…( b ) α-Helix contents of peptides in the absence (Peptide only) or presence of lipid vesicles (+ EPC-SUVs or + EPC/EPG-SUVs). Data for A2-17 are from our previous study 11 . ** p < 0.01; *** p < 0.001; **** p < 0.0001; n.s., not significant.…”

“…We have previously demonstrated that the amphipathic α-helical peptide A2-17 exhibits a higher affinity for lipid membranes and deeper insertion into lipid membrane interiors, resulting in greater efficiency of cell membrane penetration compared with non-amphipathic ARPs such as Tat, polyarginines, and Rev 11 , 12 . The proposed mechanism underlying the direct membrane penetration of highly charged non-amphipathic ARPs is that they penetrate lipid membranes through the hydrophilic domain of transient membrane defects or pores driven by the interaction between arginine residues in peptides and phosphate groups of lipids 35 – 38 .…”

“…The amphipathicity of ARPs generally plays a crucial role in their membrane penetration 9 , 10 . We have previously developed an amphipathic α-helical peptide, A2-17, with a relatively high ability to directly penetrate cell membranes even at the low peptide concentration at which typical ARPs such as Tat, R8, and Rev do not exhibit efficient cell penetration 11 , 12 . Although A2-17 did not induce significant cytotoxicity in our experimental conditions, a previous study has reported that amphipathic ARPs exhibits similar properties to the membrane-active antimicrobial peptides 13 , which can cause stable membrane pores or destroy the lipid membrane barrier.…”