Amphiphilic Triazolyl Peptides: Synthesis and Evaluation as Nanostructures

A new class of amphiphilic triazolyl peptides was designed and synthesized from peptide-based building blocks containing alkyne and azide functional groups namely linear (W(pG))3, cyclic[W(pG)]3, and Ac-K(N3)R-NH2,where W, R, K, and pG represent tryptophan, arginine, lysine, and propargylglycine residues, respectively. The linear (W(pG))3 and cyclic [W(pG)]3 peptides containing alkyne residues were conjugated with Ac-K(N3)R-NH2 functionalized with azide group through click chemistry in the presence of CuSO4.5H2O, Cu (powder), sodium ascorbate, and N,N-disopropylethylamine in methanol:water to afford amphiphilic triazolyl linear-linear (WG(triazole-KR-NH2))3 and cyclic-linear [WG(triazole-KR-NH2)]3 peptides, respectively. The secondary structures of both peptides were similar to a distorted α-helix as shown by CD spectroscopy. TEM imaging showed that linear-linear (WG(triazole-KR-NH2))3 and cyclic-linear [WG(triazole-KR-NH2)]3 peptides formed nano-sized structures in the size range of 50-100 nm and 50-80 nm, respectively.