CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF THIAMINASE-I FROM BACILLUS-THIAMINOLYTICUS - SPACE GROUP CHANGE UPON FREEZING OF CRYSTALS

Thiaminase I (M-r = 42 100) from B. thiaminolyticus, expressed in E. c oli, has been crystallized by the vapor-diffusion method. Three crysta l forms, two of which grew from 0.1 M sodium acetate (pH = 4.6), 0.2 M ammonium sulfate and 30%(w/v) PEG 2000, have been examined by X-ray a nalysis. One crystal form diffracted to 2.5 Angstrom at room temperatu re, was orthorhombic, and had unit-cell edges of a = 87.7, b = 120.5 a nd c = 76.7 Angstrom with space group P2(1)2(1)2(1). A self-Patterson map showed a strong peak indicating noncrystallographic translational pseudosymmetry with (u, v, w) = (0.03, 0.0, 0.5). When these crystals were frozen at liquid-nitrogen temperatures, a second crystal form was observed which had unit-cell dimensions a = 85.5, b = 117.5 and c = 3 6.6 Angstrom with space group P2(1)2(1)2. A third crystal form grew fr om 0.1 M Tris (pH = 8.5), 0.2 M sodium acetate trihydrate and 28% (w/v ) PEG 6000 to produce orthorhombic crystals of space group P2(1)2(1)2( 1) with cell edges of a = 114.4, b = 123.1 and c = 92.5 Angstrom.