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 Å, α = 93.2, β = 96.7, γ = 89.2° and Z = 2), grow as long thin needles. Water content on density considerations is ∼50%. They diffract to ∼2.0Å, but give wide multiply peaked spot profiles. Crystals in space group P2₁2₁2₁ (cell dimensions a = 32.2, b = 56.0, c = 67.3Å and Z = 4), grow as clusters of thin tablets and contain ∼30% water by volume. These small crystals (∼0.4 × 0.15 × 0.1 mm) diffracted well to ∼ 1.4Å and some appreciable intensities were observed at resolutions better than 1.2Å.