Crystallization and preliminary X-ray diffraction analysis of the complex of Kunitz-type tamarind trypsin inhibitor and porcine pancreatic trypsin

摘要

The complex of Tamarindus indica Kunitz-type trypsin inhibitor and porcine trypsin has been crystallized by the sitting-drop vapour-diffusion method using ammonium acetate as precipitant and sodium acetate as buffer. The homogeneity of complex formation was checked by size-exclusion chromatography and further confirmed by reducing SDS–PAGE. The crystals diffracted to 2.0 Å resolution and belonged to the tetragonal space group P41, with unit-cell parameters a = b = 57.1, c = 120.1 Å. Preliminary X-ray diffraction analysis indicated the presence of one unit of inhibitor–trypsin complex per asymmetric unit, with a solvent content of 45%.