Crystallization and preliminary characterization of crystals of human protein kinase CK2

The heterotetrameric recombinant holoenzyme of human protein kinase CK2 was purified to homogeneity. It degraded spontaneously to a stable and fully active state in which the catalytic subunit was about 5 kDa smaller than the wild type. The degraded enzyme was crystallized using polyethylene glycol 3350 as precipitant. The crystals belong to the hexagonal space group P6₃. They have unit-cell parameters a = b = 176.0, c = 93.6 Å and diffract X-rays to at least 3.5 Å resolution. The calculated crystal packing parameter is V_M = 3.22 Å³ Da^-1, suggesting that one CK2 tetramer is contained in the asymmetric unit and that the solvent content of the unit cell is 62%.