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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Poster II

CPP 21.36: Poster

Tuesday, March 19, 2024, 18:00–20:00, Poster E

Stabilizing alpha-Helicity of a Polypeptide in Aqueous Urea — •Luis Andre Baptista dos Santos¹, Yani Zhao¹, Kurt Kremer¹, Debashish Mukherji², and Robinson Cortes-Huerto¹ — ¹Max Planck Institute for Polymer Research, Mainz, Germany — ²Quantum Matter Institute, University of British Columbia, Canada

We propose a mechanism for alpha-helix folding of polyalanine in aqueous urea that reconciles experimental and simulation studies. Over 15µs long, all-atom simulations reveal that, upon dehydrating the protein’s first solvation shell, a delicate balance between localized urea residue dipole interactions and hydrogen bonds dictates polypeptide solvation properties and structure. Our work clarifies the experimentally observed tendency of these alanine-rich systems to form secondary structures at low and intermediate urea concentrations. Moreover, it is consistent with the commonly accepted hydrogen-bond-induced helix unfolding, dominant at high urea concentrations. These results establish a structure-property relationship highlighting the importance of microscopic dipole-dipole orientations/interactions for the operational understanding of macroscopic protein solvation.

Keywords: Molecular structure; Molecules; Peptides and proteins; Solvation; Urea