Coarse-Grain Model of Ultrarigid Polymer Rods Comprising Bifunctionally Linked Peptide Bundlemers

TR Zhang and DB Yang and CJ Kloxin and DJ Pochan and JG Saven, BIOMACROMOLECULES, 25, 7904-7914 (2024).

DOI: 10.1021/acs.biomac.4c01192

Computationally designed homotetrameric helical peptide bundles have been functionalized at their N-termini to achieve supramolecular polymers, wherein individual bundles ("bundlemers") are the monomeric units. Adjacent bundles are linked via two covalent cross-links. The polymers exhibit a range of conformational properties, including formation of rigid-rods with micrometer-scale persistence lengths. Herein, a coarse-grained model is used to illuminate how molecular features affect the rod-like behavior of the polymers. With increasing affinity between bundlemer ends, a sharp transition in the persistence length is observed. Doubly linked chains exhibit larger persistence lengths and more robust formation of rigid-rod structures than singly linked chains. Chain stiffness increases with decreasing temperatures. Increasing the length of the cross-linker results in more flexible chains. This model provides insights into how molecular features control the structural properties of chains comprising doubly linked rigid bundlemers.

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