Crystallographic study of an esteroproteolytic enzyme

The esteroproteolytic enzyme, a serine protease from porcine pancreas, has been crystallized and characterized by X-ray diffraction. Two closely related crystal forms were observed. The unit cell dimensions of the first form are a = 59.2 A ̊, b = 96.4 A ̊ and c = 47.4 A ̊, space group P2₁2₁2 with one molecule (mol. wt 30,000) per asymmetric unit. The unit cell dimensions of the second form are a = 59.2 A ̊, b = 96.4 A ̊ and c = 94.8 A ̊, space group P2₁2₁2₁. Mercury derivatives of enzyme inhibitors were used to obtain multiple isomorphous heavy-atom substituents suitable for phase determination.