Natural and artificial β-sheet assemblies often form helical structures due to the inherent twisting of peptide strands, typically observable by AFM and TEM but rarely analysed with single crystal X-ray diffraction (SCD) due to structural disorder. This study overcame such challenges by periodically cross-linking peptide strands in β-sheet tapes via metal coordination, creating perfectly ordered helical structures suitable for SCD analysis. Side chain interactions were found to drive helical twisting, and adjusting side chain substituents enabled tuning of the helical morphology, including the formation of double helices. These findings open new possibilities in β-sheet assembly design, advancing peptide engineering.
