Conformations of peptoids in nanosheets result from the interplay of backbone energetics and intermolecular interactions

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 22; pp. 5647 - 5651
• Main Authors: Edison, John R., Spencer, Ryan K., Butterfoss, Glenn L., Hudson, Benjamin C., Hochbaum, Allon I., Paravastu, Anant K., Zuckermann, Ronald N., Whitelam, Stephen
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 29.05.2018; Proceedings of the National Academy of Sciences
• Subjects: Backbone; BASIC BIOLOGICAL SCIENCES; Bioenergetics; Biological Sciences; Biomimetic Materials - chemistry; Computer simulation; Experimental data; MATERIALS SCIENCE; Molecular biology; Molecular dynamics; Molecular Dynamics Simulation; Molecular structure; Nanosheets; Nanostructure; Nanostructures - chemistry; Nanostructures - ultrastructure; Peptides; Peptoids - chemistry; Physical Sciences; Polymers; Protein Structure, Secondary; Quantum mechanics; Quantum physics; Rotational states; peptoid secondary structure; biomimetic sequence-specific polymers; cis-amide; 2D supramolecular assembly
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1800397115

The conformations adopted by the molecular constituents of a supramolecular assembly influence its large-scale order. At the same time, the interactions made in assemblies by molecules can influence their conformations. Here we study this interplay in extended flat nanosheets made from nonnatural sequence-specific peptoid polymers. Nanosheets exist because individual polymers can be linear and untwisted, by virtue of polymer backbone elements adopting alternating rotational states whose twists oppose and cancel. Using molecular dynamics and quantum mechanical simulations, together with experimental data, we explore the design space of flat nanostructures built from peptoids. We show that several sets of peptoid backbone conformations are consistent with their being linear, but the specific combination observed in experiment is determined by a combination of backbone energetics and the interactions made within the nanosheet. Our results provide a molecular model of the peptoid nanosheet consistent with all available experimental data and show that its structure results from a combination of intraand intermolecular interactions.