X-ray Crystal Structure of Chemically Synthesized Crambin-{alpha}carboxamide

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.216 

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Role of a salt bridge in the model protein crambin explored by chemical protein synthesis: X-ray structure of a unique protein analogue, [V15A]crambin-alpha-carboxamide.

Bang, D.Tereshko, V.Kossiakoff, A.A.Kent, S.B.

(2009) Mol Biosyst 5: 750-756

  • DOI: https://doi.org/10.1039/b903610e
  • Primary Citation of Related Structures:  
    2FD7, 2FD9

  • PubMed Abstract: 

    We have used total chemical synthesis to prepare [V15A]crambin-alpha-carboxamide, a unique protein analogue that eliminates a salt bridge between the delta-guanidinium of the Arg(10) side chain and the alpha-carboxylate of Asn(46) at the C-terminus of the polypeptide chain. This salt bridge is thought to be important for the folding and stability of the crambin protein molecule. Folding, with concomitant disulfide bond formation, of the fully reduced [V15A]crambin-alpha-carboxamide polypeptide was less efficient than folding/disulfide formation for the [V15A]crambin polypeptide under a standard set of conditions. To probe the origin of this less efficient folding/disulfide bond formation, we separately crystallized purified synthetic [V15A]crambin-alpha-carboxamide and chemically synthesized [V15A]crambin and solved their X-ray structures. The crystal structure of [V15A]crambin-alpha-carboxamide showed that elimination of the Arg(10)-Asn(46) salt bridge caused disorder of the C-terminal region of the polypeptide chain and affected the overall 'tightness' of the structure of the protein molecule. These studies, enabled by chemical protein synthesis, strongly suggest that in native crambin the Arg(10)-Asn(46) salt bridge contributes to efficient formation of correct disulfide bonds and also to the well-ordered structure of the protein molecule.

  • Organizational Affiliation

    Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Crambin46N/AMutation(s): 0 
Find proteins for P01542 (Crambe hispanica subsp. abyssinica)
Explore P01542 
Go to UniProtKB:  P01542
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01542
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.216 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.581α = 90
b = 67.581β = 90
c = 39.487γ = 120
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-01-16
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance