Crystal structure of the bovine α-chymotrypsin:kunitz inhibitor complex. An example of multiple protein:protein recognition sites
✍ Scribed by Clemente Capasso; Menico Rizzi; Enea Menegatti; Paolo Ascenzi; Martino Bolognesi
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 226 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0952-3499
No coin nor oath required. For personal study only.
✦ Synopsis
The crystal structure of bovine ␣-chymotrypsin (␣-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 Å resolution (R-factor = 0.18). The proteinase:inhibitor complex forms a compact dimer (two ␣-CHT and two BPTI molecules), which may be stabilized by surfacebound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between ␣-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P 1 residue of BPTI, however, does not occupy the ␣-CHT S 1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217.