Glycosylated interleukin‐2 (glyIL‐2) has been crystallized in two crystal forms, and unglycosylated interleukin‐2 (uIL‐2) has been crystallized in three forms. The glycosylated form of the human recombinant IL‐2 has been crystallized from 1.9 M ammonium sulfate, pH 6.5 to 7.0 in the hexagonal space group P6222 or its enantiomorph. The crystals diffract to 2.8 Å and contain two or three molecules per asymmetric unit. A second crystal form grows from 1.4 to 1.5 M ammonium sulfate in 0.2 M ammonium acetate, pH 5.0–5.5, as polycrystalline rosettes which are not suitable for even a preliminary crystallographic analysis. The uIL‐2 crystallizes from 1.0 to 1.7 M ammonium sulfate, 0.2 M ammonium acetate, pH 4.5–5.6 in the monoclinic space group P21, and less frequently in the orthorhombic space group P212121 from 2.5 M ammonium sulfate, pH 4.5 to 5.7. Cross‐seeding uIL‐2 with seeds from hexagonal crystals of glyIL‐2 promotes nucleation of trigonal crystals of unglycosylated IL‐2. These trigonal crystals belong to the space group P3121 or its enantiomorph, with similar cell dimensions to the glyIL‐2 hexagonal crystals.
- protein crystallography