PDBe 2nqd

X-ray diffraction
1.75Å resolution

Crystal structure of cysteine protease inhibitor, chagasin, in complex with human cathepsin L


Function and Biology Details

Reaction catalysed:
Specificity close to that of papain. As compared to cathepsin B, cathepsin L exhibits higher activity toward protein substrates, but has little activity on Z-Arg-Arg-NHMec, and no peptidyl-dipeptidase activity. 
Biochemical function:
Biological process:
Cellular component:

Structure analysis Details

Assembly composition:
hetero dimer (preferred)
Entry contents:
2 distinct polypeptide molecules
Macromolecules (2 distinct):
Chagasin Chain: A
Molecule details ›
Chain: A
Length: 109 amino acids
Theoretical weight: 11.92 KDa
Source organism: Trypanosoma cruzi
Expression system: Escherichia coli BL21
  • Canonical: Q966X9 (Residues: 2-110; Coverage: 99%)
Gene name: cha
Sequence domains: Chagasin family peptidase inhibitor I42
Cathepsin L1 heavy chain Chain: B
Molecule details ›
Chain: B
Length: 221 amino acids
Theoretical weight: 24.29 KDa
Source organism: Homo sapiens
Expression system: Komagataella pastoris
  • Canonical: P07711 (Residues: 113-333; Coverage: 70%)
Gene names: CTSL, CTSL1
Sequence domains: Papain family cysteine protease
Structure domains: Cysteine proteinases

Ligands and Environments

No modified residues

Experiments and Validation Details

Entry percentile scores
Spacegroup: P21
Unit cell:
a: 59.27Å b: 50.063Å c: 65.008Å
α: 90° β: 103.44° γ: 90°
R R work R free
0.151 0.148 0.188
Expression systems:
  • Escherichia coli BL21
  • Komagataella pastoris