Antiparallel coiled coil hexamer formed by de novo peptides (ACC-Hex2).

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.220 
  • R-Value Observed: 0.225 

wwPDB Validation   3D Report Full Report

This is version 2.0 of the entry. See complete history


The Phe-Ile Zipper: A Specific Interaction Motif Drives Antiparallel Coiled-Coil Hexamer Formation.

Spencer, R.K.Hochbaum, A.I.

(2017) Biochemistry 56: 5300-5308

  • DOI: https://doi.org/10.1021/acs.biochem.7b00756
  • Primary Citation of Related Structures:  
    5VTE, 5W0J

  • PubMed Abstract: 

    Coiled coils are a robust motif for exploring amino acid interactions, generating unique supramolecular structures, and expanding the functional properties of biological materials. A recently discovered antiparallel coiled-coil hexamer (ACC-Hex, peptide 1) exhibits a unique interaction in which Phe and Ile residues from adjacent α-helices interact to form a Phe-Ile zipper within the hydrophobic core. Analysis of the X-ray crystallographic structure of ACC-Hex suggests that the stability of the six-helix bundle relies on specific interactions between the Phe and Ile residues. The Phe-Ile zipper is unprecedented and represents a powerful tool for utilizing the Phe-Ile interactions to direct supramolecular assembly. To further probe and understand the limits of the Phe-Ile zipper, we designed peptide sequences with natural and unnatural amino acids placed at the Phe and Ile residue positions. Using size exclusion chromatography and small-angle X-ray scattering, we found that the proper assembly of ACC-Hex from monomers is sensitive to subtle changes in side chain steric bulk and hydrophobicity introduced by mutations at the Phe and Ile residue positions. Of the sequence variants that formed ACC-Hex, mutations in the hydrophobic core significantly affected the stability of the hexamer, from a ΔG u w of 2-8 kcal mol -1 . Additional sequences were designed to further probe and enhance the stability of the ACC-Hex system by maximizing salt bridging between the solvent-exposed residues. Finally, we expanded on the generality of the Phe-Ile zipper, creating a unique sequence that forms an antiparallel hexamer that is topologically similar to ACC-Hex but atomistically unique.

  • Organizational Affiliation

    Department of Chemistry and Department of Chemical Engineering & Materials Science, University of California, Irvine , Irvine, California 92697-2575, United States.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
peptide 1
A, B
31synthetic constructMutation(s): 0 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on CL

Download Ideal Coordinates CCD File 
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on PHI
A, B
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.220 
  • R-Value Observed: 0.225 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 52.56α = 90
b = 52.56β = 90
c = 93.04γ = 120
Software Package:
Software NamePurpose
iMOSFLMdata reduction
Aimlessdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2017-10-04
    Type: Initial release
  • Version 1.1: 2017-10-11
    Changes: Database references
  • Version 1.2: 2017-10-25
    Changes: Database references
  • Version 2.0: 2022-12-14
    Changes: Atomic model, Data collection, Database references, Derived calculations, Non-polymer description, Polymer sequence, Source and taxonomy, Structure summary