[Effect of amino acid sequence and time on nanofiber formation of self-assembly peptides].

Different spider fibroin non crystalline motifs GGAS and GPGGY were inserted into the middle of RADA16-I . The resulting peptides were R1 (n-RADARADAGGASRADARADA-c) and R2 (n-RADARADAGPGGYRADARADA-c). Fourier transform infrared spectrum (FTIR) was used to identify the secondary structure, while atomic force microscopy (AFM) and transmitting electron microscope (TEM) were used to investigate nanofiber formation of the peptides. These results illustrate that R1 and R2 form random coils and self-assemble into short fibrillar nanostructures. R1 and R2 display a noticeable change in the formation of nanofibers with time. They become longer and wider with the increase of beta-sheet content. R1 forms less and longer fibers than R2; the nanofibers formed by R2 have bend. These characteristics provide a close correlation for the roles of amino acid sequence and beta-sheet structure in nanofiber formation.