Development of a Cell penetrating Peptide that Exhibits Responsive Changes in its Secondary Structure in the Cellular Environment
Cell penetrating peptides (CPP) are received a lot of attention as an intracellular delivery tool for hydrophilic molecules such as drugs, proteins, and DNAs. We designed and synthesized nona arginine analogues 1 5 [FAM b Ala (l Arg l Arg l Pro)3 (Gly)3 NH2 (1) FAM b Ala (l Arg l Arg l ProNH2)3 (Gly)3 NH2 (2) FAM b Ala (l Arg l Arg l ProGu)3 (Gly)3 NH2 (3) FAM b Ala (l Arg)2 (l ProGu)2 (l Arg)4 l ProGu (Gly)3 NH2 (4) and FAM b Ala (l Arg)6 (l ProGu)3 (Gly)3 NH2 (5) containing l proline (l Pro) or cationic proline derivatives (l ProNH2 and l ProGu) and investigated their cell penetrating abilities. Interestingly, only peptide 3 having the side chain guanidinyl l ProGu exhibited a secondary structural change in cellular environment. Specifically, peptide 3 formed a random structure in hydrophilic conditions, whereas it formed a helical structure under amphipathic conditions. Furthermore, during cellular permeability tests, peptide 3 demonstrated greater cell penetrating activity than other peptides and effectively transported plasmid DNA into HeLa cells. Thus, l ProGu containing peptide 3 may be a useful candidate as a gene delivery carrier.
Scientific reports