[X-ray structural study of the crystalline structure of human progastricsin by a molecular replacement method].

The human progastricsin crystal structure has been solved by the molecular replacement method. The intensities of reflections from native progastricsin crystals were measured at the 4.0 A resolution by the omega-scan method with a Nicolet P3 diffractometer operated in automatic regime. To determine the orientation and position of progastricsin molecules in the unit cell, programme packages MERLOT and BRUTE were applied running on a MicroVAX-II computer. Prior to the translation search, several rotation function peaks were subjected to a rigid body refinement against the correlation coefficient between the observed and calculated structure factors. This approach clearly identified the correct orientation of the molecule. The solution obtained from the BRUTE translation function map was refined by the 6-dimensional correlation search and then by programme CORELS. The human progastricsin molecules packing in the crystal unit ell is described.