X-ray crystallographic characterization and phasing of a fucose-specific lectin from Aleuria aurantia

A fucose-specific lectin from Aleuria aurantia was crystallized in its native form and was also cocrystallized with HgCl(2). Crystallization was performed using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. Both the Hg-free native crystals and the Hg cocrystals belong to the hexagonal space group P6(5)22. The unit-cell parameters for the Hg-free form are a = 84.0, c = 250.1 A and for the Hg cocrystals are a = 83.9, c = 254.3 A. Both forms of the crystals diffract X-rays to 2.3 A resolution and are suitable for high-resolution crystal structure determination. Initial phasing was successfully performed by the MAD method using the Hg cocrystals and the electron density obtained was good enough for model building.