Crystallization and preliminary X-ray analysis of two new crystal forms of calmodulin.

Two new crystal forms of calmodulin from Gallus gallus are reported. Crystals in space group P1 (cell dimensions a = 59.7, b = 53.1, c = 24.6 A, alpha = 93.2, beta = 96.7, gamma = 89.2 and Z = 2), grow as long thin needles. Water content on density considerations is approximately 50%. They diffract to approximately 2.0 A but give wide multiply peaked spot profiles. Crystals in space group P2(1)2(1)2(1) (cell dimensions a = 32.2, b = 56.0, c = 67.3 A and Z = 4), grow as clusters of thin tablets and contain approximately 30% water by volume. These small crystals ( approximately 0.4 x 0.15 x 0.1 mm) diffracted well to approximately 1.4 A and some appreciable intensities were observed at resolutions better than 1.2 A.