Figure 2.

(a) Optimized crystal obtained after 2–3 d by mixing 2 µl protein solution (30 mg ml⁻¹) at 50 mM Tris–HCl pH 7.8, 300 mM NaCl, 5%(v/v) glycerol, 1 mM EDTA, 2 mM β-mercaptoethanol with an equal volume of reservoir solution consisting of 0.2 M ammonium acetate, 0.1 M sodium acetate trihydrate pH 4.6, 30% PEG 4000 and equilibrating against 500 µl reservoir solution over which 200 µl Al’s oil was added at 277 K. (b) The X-ray diffraction image of an spMCAT crystal at ϕ = 90° collected at the Shanghai Synchrotron Radiation Facility (SSRF), China.