A fully functional deletion staphylokinase derivative crystallizes in two non-isomorphous monoclinic modifications

Two non-isomorphous monoclinic types of diffraction-quality crystals of Δ10Sak, a fully functional staphylokinase derivative lacking the first ten amino acids, have been grown by the hanging-drop vapour-diffusion technique. Type I crystals grow from a solution containing Zn(OAc)₂, Tris buffer pH 7.5 and PEG 8000, while type II crystals can be obtained from a solution containing MgCl₂, Tris buffer pH 8.5 and PEG 4000. Both crystal types were suitable for data collection (to 2.4 and 2.6 Å resolution, respectively) and further structural investigation.