X-ray crystal structure of allo-Thr31-ShK

Experimental Data Snapshot

  • Resolution: 1.30 Å
  • R-Value Free: 0.169 
  • R-Value Work: 0.127 
  • R-Value Observed: 0.130 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Inversion of the Side-Chain Stereochemistry of Indvidual Thr or Ile Residues in a Protein Molecule: Impact on the Folding, Stability, and Structure of the ShK Toxin.

Dang, B.Shen, R.Kubota, T.Mandal, K.Bezanilla, F.Roux, B.Kent, S.B.

(2017) Angew Chem Int Ed Engl 56: 3324-3328

  • DOI: https://doi.org/10.1002/anie.201612398
  • Primary Citation of Related Structures:  
    5I5A, 5I5B, 5I5C

  • PubMed Abstract: 

    ShK toxin is a cysteine-rich 35-residue protein ion-channel ligand isolated from the sea anemone Stichodactyla helianthus. In this work, we studied the effect of inverting the side chain stereochemistry of individual Thr or Ile residues on the properties of the ShK protein. Molecular dynamics simulations were used to calculate the free energy cost of inverting the side-chain stereochemistry of individual Thr or Ile residues. Guided by the computational results, we used chemical protein synthesis to prepare three ShK polypeptide chain analogues, each containing either an allo-Thr or an allo-Ile residue. The three allo-Thr or allo-Ile-containing ShK polypeptides were able to fold into defined protein products, but with different folding propensities. Their relative thermal stabilities were measured and were consistent with the MD simulation data. Structures of the three ShK analogue proteins were determined by quasi-racemic X-ray crystallography and were similar to wild-type ShK. All three ShK analogues retained ion-channel blocking activity.

  • Organizational Affiliation

    Department of Chemistry, Department of Biochemistry & Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, 60637, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C
35Stichodactyla helianthusMutation(s): 0 
Find proteins for P29187 (Stichodactyla helianthus)
Explore P29187 
Go to UniProtKB:  P29187
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP29187
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.30 Å
  • R-Value Free: 0.169 
  • R-Value Work: 0.127 
  • R-Value Observed: 0.130 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 30.743α = 90
b = 46.229β = 108.02
c = 40.064γ = 90
Software Package:
Software NamePurpose
XDSdata reduction
XDSdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2017-01-25
    Type: Initial release
  • Version 1.1: 2017-03-08
    Changes: Database references
  • Version 1.2: 2017-03-29
    Changes: Database references
  • Version 1.3: 2023-09-27
    Changes: Data collection, Database references, Refinement description