Three-dimensional structure of the complex between pancreatic secretory trypsin inhibitor (Kazal type) and trypsinogen at 1.8 Å resolution

摘要: Abstract The three-dimensional structure of the proteic complex formed by bovine trypsinogen and porcine pancreatic secretory trypsin inhibitor (Kazal type) has been solved means Patterson search techniques, using a predicted model trypsin-ovomucoid ( Papamokos et al., 1982 ). complex, including 162 solvent molecules, refined at 1.8 A resolution (26,341 unique reflections) to conventional crystallographic R factor 0.195. molecule binds via hydrogen bonds and/or apolar interactions sites P9, P7, P6, P5, P3, P1, P1′, P2′ P3′ contact area. itself resembles closely that third domain Japanese quail ovomucoid inhibitor, recently reported Weber al. (1981) . part trypsin, as is case in trypsinogen-basic but two segments activation adopt different conformation. Most notably N-terminal region Ile16-Gly19 loop, which disordered free Huber & Bode, 1978 ), assumes regular polypeptide chain can be traced far residue Asp14. This new fixed allows formation buried salt link between side-chains Lys156 Asp194. Conformations differing from those are also found for residues 20 28 141 155. Some structural perturbation observed other parts molecule, calcium loop.