25 mg/mL FosAKP in 10 mM Hepes, pH 7.5, 75 mM NaCl was supplemented with 6 mM MnCl2 and mixed with an equal volume of 16% (w/v) PEG3350, 0.25 M MgCl2, 0.2 M KBr, 0.1 M BisTris, pH 5.5 and 1/10 volume of seed stock in 26% (w/v) PEG3350, 0.25 M MgCl2, 0.2 M KBr, 0.1 M BisTris, pH 5.5. From this, approximately 14 uL were added per window of the fixed-target chip. The sample holder was then inserted for into a 3D-printed crystal growth chamber with 3 mL of precipitant solution in the bottom for vapor-diffusion crystallization and incubated at 20C.
Before data collection sample holder was removed from the crystal growth chamber and excess precipitant was removed by blotting through the micropores of the membranes, before 10 uL of crystallization solution with 5 % DMSO were pipetted to the crystals in the individual compartments. Sample holders were then placed back into the growths vessel and incubated for 24h. Before data collection blotting was repeated for removal of excess liquid in order to minimize background scattering. Sample holders were then equipped with a protective cover to prevent them from drying-out and stored in a humid atmosphere (figure ??). Compound addition and liquid removal were conducted in a glove box with >95% rel. humidity.
