Self-assembled peptide fibers from valylvaline bola-amphiphiles by a parallel beta-sheet network

A series of dipeptide-based bola-amphiphiles, bis(N-alpha-amide-L-valyl-L-valine) 1, n-alkane dicarboxylate (n=4-12), have been synthesized. The bola-amphiphiles with n=4 and 6 self-assembled to form crystalline solids in water, whereas those with n=7-12 produced peptide fibers. FT-IR spectroscopy and X-ray diffraction patterns revealed that the peptide fibers have parallel-type beta-sheet networks between the valylvaline units. FT-IR deconvolution study of carboxyl regions indicated that these crystalline solids and peptide fibers are stabilized by interlayer bifurcated and intralayer lateral hydrogen-bond networks between the end carboxylic acid groups, respectively.