Elucidation of the structure of supramolecular polymorphs in peptide nanofibres using Raman spectroscopy

Peptide fibre formation via molecular self-assembly is a key step in range of cellular processes and increasingly considered as an approach to produce supramolecular biomaterials. We previously demonstrated the tripeptide lysine-dityrosine (KYY) substrate for proton-conducting melanin-like materials. Point based Raman scattering one several techniques which were used characterise secondary structure KYY nanofibre but often case with this type fibre, spectra are rather complex addition there variations intensity between samples making interpretation difficult. Using mapping we show that, drop solution dries, it self-assembles into two different forms simpler obtained each easier interpret. The tyrosine amide marker bands, 852 828 cm−1, present both similar intensities indicating some stacking rings. However, bands at 1614 1661 cm−1 vary considerably forms. It concluded that consist stacked polypeptide units joined by hydrogen bonds form structures β-sheet longer peptides. There other clear differences such large difference lysine side chain band 1330 relative 982 1034 cm−1. These attributed changes conformation chains causing electron withdrawing effects on ring.