Crystallization and preliminary X-ray study of porcine trypsin, free and complexed with Ecballium elaterium trypsin inhibitor, a member of the squash inhibitors family

Porcine trypsin has been crystallized either free or complexed with synthetic Ecballium elaterium trypsin inhibitor II, a 28-residue peptide with three disulfide bridges. The crystals diffract beyond 2·0 Å. Crystals are orthorhombic, space group P212121, with cell dimensions a = 77·32 Å, b = 53·81 Å, c = 46·91 Å, for the free trypsin, and a = 62·25 Å, b = 62·27 Å, c = 84·66 Å for the complex with E. elaterium trypsin inhibitor II.