Crystallization of the tetramer of histones H3 and H4

Crystals of the histone tetramer (H3-H4)2 from calf thymus have been grown. The crystals yield x-ray diffraction patterns with Bragg spacings as small as 3.5 angstroms. Crystals grown from two types of preparations have the symmetry of the space group P61 (or P65). The best crystals were grown from histones that had the amino terminal arms removed by mild trypsinization.