title: X-ray Crystallographic Structure and Solution Behavior of an Antiparallel Coiled-Coil Hexamer Formed by de Novo Peptides.
abstract: The self-assembly of peptides and proteins into higher-ordered structures is encoded in the amino acid sequence of each peptide or protein. Understanding the relationship among the amino acid sequence, the assembly dynamics, and the structure of well-defined peptide oligomers expands the synthetic toolbox for these structures. Here, we present the X-ray crystallographic structure and solution behavior of de novo peptides that form antiparallel coiled-coil hexamers (ACC-Hex) by an interaction motif neither found in nature nor predicted by existing peptide design software. The 1.70 Å X-ray crystallographic structure of peptide 1a shows six α-helices associating in an antiparallel arrangement around a central axis comprising hydrophobic and aromatic residues. Size-exclusion chromatography studies suggest that peptides 1 form stable oligomers in solution, and circular dichroism experiments show that peptides 1 are stable to relatively high temperatures. Small-angle X-ray scattering studies of the solution behavior of peptide 1a indicate an equilibrium of dimers, hexamers, and larger aggregates in solution. The structures presented here represent a new motif of biomolecular self-assembly not previously observed for de novo peptides and suggest supramolecular design principles for material scaffolds based on coiled-coil motifs containing aromatic residues.
authors.affiliation: Department of Chemistry and Department of Chemical Engineering & Materials Science, University of California, Irvine , Irvine, California 92697-2575, United States.
authors.forename: Ryan K
authors.initials: RK
authors.lastname: Spencer
authors.affiliation: Department of Chemistry and Department of Chemical Engineering & Materials Science, University of California, Irvine , Irvine, California 92697-2575, United States.
authors.forename: Allon I
authors.initials: AI
authors.lastname: Hochbaum
mesh_terms: D002942:Circular Dichroism; D018360:Crystallography, X-Ray / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D053838:Scattering, Small Angle
chemical_list: D010446:Peptide Fragments