1JBN

Solution structure of an acyclic permutant of SFTI-1, A trypsin inhibitor from sunflower seeds


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the least restraint violations,structures with the lowest energy 

wwPDB Validation 3D Report Full Report


This is version 1.4 of the entry. See complete history

Literature

Solution structures by 1H NMR of the novel cyclic trypsin inhibitor SFTI-1 from sunflower seeds and an acyclic permutant.

Korsinczky, M.L.Schirra, H.J.Rosengren, K.J.West, J.Condie, B.A.Otvos, L.Anderson, M.A.Craik, D.J.

(2001) J.Mol.Biol. 311: 579-591

  • DOI: 10.1006/jmbi.2001.4887
  • Primary Citation of Related Structures:  1JBL

  • PubMed Abstract: 
  • SFTI-1 is a recently discovered cyclic peptide trypsin inhibitor from sunflower seeds comprising 14 amino acid residues. It is the most potent known Bowman-Birk inhibitor and the only naturally occurring cyclic one. The solution structure of SFTI-1 h ...

    SFTI-1 is a recently discovered cyclic peptide trypsin inhibitor from sunflower seeds comprising 14 amino acid residues. It is the most potent known Bowman-Birk inhibitor and the only naturally occurring cyclic one. The solution structure of SFTI-1 has been determined by 1H-NMR spectroscopy and compared with a synthetic acyclic permutant. The solution structures of both are remarkably similar. The lowest energy structures from each family of 20 structures of cyclic and acyclic SFTI-1 have an rmsd over the backbone and heavy atoms of 0.29 A and 0.66 A, respectively. The structures consist of two short antiparallel beta-strands joined by an extended loop containing the active site at one end. Cyclic SFTI-1 also has a hairpin turn completing the cycle. Both molecules contain particularly stable arrangements of cross-linking hydrogen bonds between the beta-strands and a single disulfide bridge, making them rigid and well defined in solution. These stable arrangements allow both the cyclic and acyclic variants of SFTI-1 to inhibit trypsin with very high potencies (0.5 nM and 12.1 nM, respectively). The cyclic nature of SFTI-1 appears to have evolved to provide higher trypsin inhibition as well as higher stability. The solution structures are similar to the crystal structure of the cyclic inhibitor in complex with trypsin. The lack of a major conformational change upon binding suggests that the structure of SFTI-1 is rigid and already pre-organized for maximal binding due to minimization of entropic losses compared to a more flexible ligand. These properties make SFTI-1 an ideal platform for the design of small peptidic pharmaceuticals or pesticides.


    Organizational Affiliation

    Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, 4072, Australia.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CYCLIC TRYPSIN INHIBITOR
A
14Helianthus annuusGene Names: sfti1
Find proteins for Q4GWU5 (Helianthus annuus)
Go to UniProtKB:  Q4GWU5
Small Molecules
Biologically Interesting Molecules 1 Unique
IDChainsNameType/Class2D Diagram3D Interactions
PRD_001259
Query on PRD_001259
Aacyclic trypsin inhibitorPolypeptide / Trypsin inhibitor

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Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the least restraint violations,structures with the lowest energy 
  • Olderado: 1JBN Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-08-22
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2016-01-13
    Type: Other
  • Version 1.4: 2016-12-28
    Type: Structure summary