PDBe 2cio

X-ray diffraction
1.5Å resolution

The high resolution x-ray structure of papain complexed with fragments of the Trypanosoma brucei cysteine protease inhibitor ICP.

Primary publication:
High-resolution complex of papain with remnants of a cysteine protease inhibitor derived from Trypanosoma brucei.
OpenAccess logo Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 62 504-8 (2006)
PMID: 16754967

Function and Biology Details

Reaction catalysed:
Hydrolysis of proteins with broad specificity for peptide bonds, but preference for an amino acid bearing a large hydrophobic side chain at the P2 position. Does not accept Val in P1'.
Biochemical function:
Biological process:
Cellular component:
  • not assigned

Structure analysis Details

Assembly composition:
hetero dimer (preferred)
Entry contents:
2 distinct polypeptide molecules
Macromolecules (2 distinct):
Papain Chain: A
Molecule details ›
Chain: A
Length: 212 amino acids
Theoretical weight: 23.5 KDa
Source organism: Carica papaya
  • Canonical: P00784 (Residues: 134-345; Coverage: 65%)
Sequence domains: Papain family cysteine protease
Structure domains: Cysteine proteinases
Inhibitor of cysteine peptidase Chain: B
Molecule details ›
Chain: B
Length: 121 amino acids
Theoretical weight: 13.45 KDa
Source organism: Trypanosoma brucei
Expression system: Escherichia coli BL21(DE3)
  • Canonical: Q868H0 (Residues: 1-121; Coverage: 100%)
Gene name: ICP
Sequence domains: Chagasin family peptidase inhibitor I42

Ligands and Environments

2 bound ligands:

1 modified residue:

Experiments and Validation Details

Entry percentile scores
X-ray source: ESRF BEAMLINE ID29
Spacegroup: P212121
Unit cell:
a: 42.323Å b: 46.118Å c: 95.697Å
α: 90° β: 90° γ: 90°
R R work R free
0.179 0.177 0.225
Expression system: Escherichia coli BL21(DE3)