Crystallization and preliminary structural studies of neurotrophin-3.

Neurotrophin-3 (NT-3) has been crystallized in 2 forms. Orthorhombic crystals, space group P2(1)2(1)2, diffracted to 2.8 A and have cell dimensions a = 39.1 A, b = 54.0 A, and c = 65.5 A. The second form is space group P4(3)2(1)2, with cell dimensions a = b = 67.1 A, and c = 107.9 A. The tetragonal crystals diffract to 2.8 A at room temperature and 2.5 A at -100 degrees C. The unit cell dimensions change significantly upon freezing, a = b = 66.1 A, and c = 102.8 A. Phases for the orthorhombic form were obtained by molecular replacement using nerve growth factor as the search model. A partially refined model of the NT-3 dimer (75% complete) was then oriented and positioned in the tetragonal cell.