Crystallization and preliminary X-ray analysis of two different forms of mitochondrial creatine kinase from chicken cardiac muscle

Crystals of mitochondrial creatine kinase isolated from chicken heart were grown by precipitation with polyethylene glycol 1000. The enzyme has been crystallized in the absence and presence of ATP in two different space groups. Crystals are tetragonal, with space group P42(1)2, a = b = 171 A, c = 150 A in the absence of ATP; and P422, a = b = 101 A, c = 114.4 A in the presence of ATP. We suggest that there is one octamer (346 kDa) per asymmetric unit without ATP and one dimer (86 kDa) per asymmetric unit with ATP. Using synchrotron radiation, the octameric form diffracts to at least 3 A resolution.