Parallel and antiparallel peptide double β‐helices controlled by metal‐induced folding and assembly. Issue 1 (9th April 2021) - Sawada, Tomohisa
Abstract: Short peptides with sequences of alternating l ‐ and d ‐residues are known to form antiparallel double β‐helical structures, but their equilibrium structures have not been characterized in detail. Here, we use metal coordination of a simple octapeptide, ‐(l ‐Val‐d ‐Val)4 ‐, modified with two coordinating side chains at the ( i, j )‐th residues to uncover these elusive structures. When ( i, j ) = (3, 5), complexation with ZnI2 induces a parallel double β‐helix, which is not commonly seen. In contrast, when ( i, j ) = (5, 7), a commonly occurring antiparallel double β‐helix (Type I) is formed. Interestingly, complexation of the peptide with ( i, j ) = (3, 7) gives another antiparallel double β‐helix, the unknown Type II structure, which has an inverted orientation of the two strands. Complexation of a monotopic peptide ( i = 3) with trans‐ PdCl2 yields a Pd(II)‐linked dimeric bundle of two antiparallel β‐helices. These results demonstrate that metal coordination can induce even as‐yet unrecognized structures in the folding and assembly pathways of short peptides. Key points: Structural elucidation of elusive peptide nanostructures Precise structural control of double helical molecules Fusion of peptide folding and metal‐directed self‐assembly Abstract :