X-ray Crystallographic Structure of a Papain-Leupeptin Complex

FEBS Lett. 1993 Jan 2;315(1):38-42. doi: 10.1016/0014-5793(93)81128-m.


The three-dimensional structure of the papain-leupeptin complex has been determined by X-ray crystallography to a resolution of 2.1 A (overall R-factor = 19.8%). The structure indicates that: (i) leupeptin contacts the S subsites of the papain active site and not the S' subsites; (ii) the 'carbonyl' carbon atom of the inhibitor is covalently bound by the Cys-25 sulphur atom of papain and is tetrahedrally coordinated; (iii) the 'carbonyl' oxygen atom of the inhibitor faces the oxyanion hole and makes hydrogen bond contacts with Gln-19 and Cys-25.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Crystallography
  • In Vitro Techniques
  • Leupeptins / chemistry*
  • Models, Molecular
  • Molecular Sequence Data
  • Papain / ultrastructure*
  • Protein Structure, Tertiary
  • X-Ray Diffraction


  • Leupeptins
  • Papain
  • leupeptin