title: Refined 1.6 A resolution crystal structure of the complex formed between porcine beta-trypsin and MCTI-A, a trypsin inhibitor of the squash family. Detailed comparison with bovine beta-trypsin and its complex.
abstract: The crystal structure of the complex formed by porcine beta-trypsin with the MCTI-A inhibitor (Momordica charantia, Linn. Cucurbitaceae) has been determined at 1.6 A resolution using the molecular replacement method. The sequence of MCTI-A was determined by recognizing the electron density, and shows that MCTI-A is a member of the squash family of trypsin inhibitors. We report the first high-resolution structure of porcine beta-trypsin. Detailed comparisons have been made on the overall structure, solvent structure and active-site geometries between this complex and bovine beta-trypsin and its complexes. On the basis of our results, we discuss the interaction patterns between inhibitor and trypsin. Unlike other complex structures formed by bovine trypsin with inhibitors, no out-of-plane distortion around the inhibitor's scissible peptide was observed. The role of the trypsin catalytic triad is also discussed on the basis of this structure.
authors.affiliation: Institute of Physical Chemistry, Peking University, Beijing, P.R. China.
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: S
authors.initials: S
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Tang
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003198:Computer Simulation; D006860:Hydrogen Bonding; D046911:Macromolecular Substances; D010940:Plant Proteins / Q000737:chemistry*; D010944:Plants / Q000737:chemistry; D012997:Solvents; D013552:Swine; D014357:Trypsin / Q000737:chemistry*; D014361:Trypsin Inhibitors / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D046911:Macromolecular Substances; D010940:Plant Proteins; D012997:Solvents; D014361:Trypsin Inhibitors; C073802:MCTI-A protein, Momordica charantia; D014357:Trypsin