Computationally designed bundlemers for hybrid physical-covalent assembly of rigid polymers

Peptide coiled coils present a diverse toolbox for constructing new polymers that display target nanostructures and properties. Computational prediction of coiled coil-forming peptides enables chain and material construction in which coiled coils, also known as ‘bundlemers’, are the modular building blocks. We use bundlemers that form robust antiparallel homotetramers to construct hybrid physical-covalent, supramolecular polymers. By end-functionalizing peptides with complimentary ‘click’ reactive groups, bundlemers are covalently linked to form polymers displaying desired length distributions and flexibility: a short organic linker between bundlemers yields absolutely rigid rods while a flexible linker yields semi-flexible fibers. Small-Angle Neutron Scattering (SANS) along with Transmission Electron Microscopy (TEM) have been used extensively to characterize the structure of the resulting polymers. Furthermore, recombinant expression of the peptides in Escherichia Coli was used to obtain deuterated bundlemer-forming peptides. This has facilitated contrast-matching experiments in SANS with which we have characterized the stability of bundlemers in solution and also investigated the alternating bundlemer assembly design of rigid rods.