Crystallization and preliminary X-ray crystallographic analysis of probable amylase/protease inhibitor-B from rice seeds.

Abstract Large crystals of probable amylase/protease inhibitor-B have been grown at room temperature from ammonium sulfate solution. The crystals grow within five days to dimensions of 0·6 mm × 0·6 mm × 0·6 mm. They diffract to at least 1·7 A upon exposure to synchrotron X-rays. The crystals belong to the space group P 4 1 2 1 2 (or P 4 3 2 1 2) with unit cell dimensions of a = 38·02 A and c = 98·98 A. The presence of one molecule per asymmetric unit gives the unit cell volume per protein mass ( V m ) of 1·99 A 3 /Da and the solvent fraction of 38·2% by volume. X-ray data have been collected to 2·0 A Bragg spacing from native crystals.