1O8Y

Solution structure of SFTI-1(6,5), an acyclic permutant of the proteinase inhibitor SFTI-1, trans-trans-trans conformer (tt-A)


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: LEAST OVERALL ENERGIES 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Enzymatic Cyclization of a Potent Bowman-Birk Protease Inhibitor, Sunflower Trypsin Inhibitor-1, and Solution Structure of an Acyclic Precursor Peptide

Marx, U.C.Korsinczky, M.Schirra, H.Jones, A.Condie, B.Otvos, L.Craik, D.J.

(2003) J.Biol.Chem. 278: 21782

  • DOI: 10.1074/jbc.M212996200
  • Primary Citation of Related Structures:  1O8Z

  • PubMed Abstract: 
  • The most potent known naturally occurring Bowman-Birk inhibitor, sunflower trypsin inhibitor-1 (SFTI-1), is a bicyclic 14-amino acid peptide from sunflower seeds comprising one disulfide bond and a cyclic backbone. At present, little is known about t ...

    The most potent known naturally occurring Bowman-Birk inhibitor, sunflower trypsin inhibitor-1 (SFTI-1), is a bicyclic 14-amino acid peptide from sunflower seeds comprising one disulfide bond and a cyclic backbone. At present, little is known about the cyclization mechanism of SFTI-1. We show here that an acyclic permutant of SFTI-1 open at its scissile bond, SFTI-1[6,5], also functions as an inhibitor of trypsin and that it can be enzymatically backbone-cyclized by incubation with bovine beta-trypsin. The resulting ratio of cyclic SFTI-1 to SFTI-1[6,5] is approximately 9:1 regardless of whether trypsin is incubated with SFTI-1[6,5] or SFTI-1. Enzymatic resynthesis of the scissile bond to form cyclic SFTI-1 is a novel mechanism of cyclization of SFTI-1[6,5]. Such a reaction could potentially occur on a trypsin affinity column as used in the original isolation procedure of SFTI-1. We therefore extracted SFTI-1 from sunflower seeds without a trypsin purification step and confirmed that the backbone of SFTI-1 is indeed naturally cyclic. Structural studies on SFTI-1[6,5] revealed high heterogeneity, and multiple species of SFTI-1[6,5] were identified. The main species closely resembles the structure of cyclic SFTI-1 with the broken binding loop able to rotate between a cis/trans geometry of the I7-P8 bond with the cis conformer being similar to the canonical binding loop conformation. The non-reactive loop adopts a beta-hairpin structure as in cyclic wild-type SFTI-1. Another species exhibits an iso-aspartate residue at position 14 and provides implications for possible in vivo cyclization mechanisms.


    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
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 20 
  • Selection Criteria: LEAST OVERALL ENERGIES 
  • Olderado: 1O8Y Olderado

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-03-13
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance