PDBe 3ima

X-ray diffraction
2.03Å resolution

Complex strcuture of tarocystatin and papain

Entry authors: Chu MH, Liu KL, Yeh KW, Cheng YS

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 Chains: A, C
Molecule details ›
Chains: A, C
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
Cysteine proteinase inhibitor Chains: B, D
Molecule details ›
Chains: B, D
Length: 91 amino acids
Theoretical weight: 10.2 KDa
Source organism: Colocasia esculenta
Expression system: Escherichia coli
  • Canonical: Q8L5J8 (Residues: 2-92; Coverage: 44%)
Gene name: CPI
Sequence domains: Aspartic acid proteinase inhibitor
Structure domains: Nuclear Transport Factor 2; Chain: A,

Ligands and Environments

1 bound ligand:

1 modified residue:

Experiments and Validation Details

Entry percentile scores
X-ray source: NSRRC BEAMLINE BL13C1
Spacegroup: P212121
Unit cell:
a: 36.06Å b: 99.72Å c: 165.59Å
α: 90° β: 90° γ: 90°
R R work R free
0.182 0.182 0.233
Expression system: Escherichia coli