Solution structure of gamma 1-H and gamma 1-P thionins from barley and wheat endosperm determined by 1H-NMR: a structural motif common to toxic arthropod proteins

Biochemistry. 1993 Jan 19;32(2):715-24. doi: 10.1021/bi00053a041.


The complete assignment of the proton NMR spectra of the homologous gamma 1-hordothionin and gamma 1-purothionin (47 amino acids, 4 disulfide bridges) from barley and wheat, respectively, has been performed by two-dimensional sequence-specific methods. A total of 299 proton-proton distance constraints for gamma 1-H and 285 for gamma 1-P derived from NOESY spectra have been used to calculate the three-dimensional solution structures. Initial structures have been generated by distance geometry methods and further refined by dynamical simulated annealing calculations. Both proteins show identical secondary and tertiary structure with a well-defined triple-stranded antiparallel beta-sheet (residues 1-6, 31-34, and 39-47), an alpha-helix (residues 16-28), and the corresponding connecting loops. Three disulfide bridges are located in the hydrophobic core holding together the alpha-helix and the beta-sheet and forming a cysteine-stabilized alpha-helical (CSH) motif. Moreover, a clustering of positive charges is observed on the face of the beta-sheet opposite to the helix. The three-dimensional structures of the gamma-thionins differ remarkably from plant alpha- and beta-thionins and crambin. However, they show a higher structural analogy with scorpion toxins and insect defensins which also present the CSH motif.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antimicrobial Cationic Peptides
  • Arthropod Venoms / chemistry*
  • Hordeum / chemistry*
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Sequence Data
  • Plant Proteins / chemistry*
  • Protein Conformation
  • Protons
  • Sequence Homology, Amino Acid
  • Triticum / chemistry*


  • Antimicrobial Cationic Peptides
  • Arthropod Venoms
  • Plant Proteins
  • Protons
  • hordothionin protein, Hordeum vulgare
  • purothionin