Amphipathic short helix-stabilized peptides with cell-membrane penetrating ability

We synthesized four types of arginine-based amphipathic nonapeptides, including two homochiral peptides, R-(L-Arg-L-Arg-Aib)(3)-NH2 (R = 6-FAM-beta-Ala: FAM-1; R = Ac: Ac-1) and R-(D-Arg-D-Arg-Aib)(3)-NH2 (R = 6-FAM-beta-Ala: ent-FAM-1; R = Ac: ent-Ac-1); a heterochiral peptide, R-(L-Arg-D-Arg-Aib)(3)-NH2 (R = 6-FAM-beta-Ala: FAM-2; R = Ac: Ac-2); and a racemic mixture of diastereomeric peptides, R-(rac-Arg-rac-Arg-Aib)(3)-NH2 (R = 6-FAM-beta-Ala: FAM-3; R = Ac: Ac-3), and then investigated the relationship between their secondary structures and their ability to pass through cell membranes. Peptides 1 and ent-1 formed stable one-handed a-helical structures and were more effective at penetrating HeLa cells than the non-helical peptides 2 and 3. (C) 2014 Elsevier Ltd. All rights reserved.