Fig. 3
(A, B) Cryo-TEM imaging of fibrous protein in vitreous ice obtained approx. 10 min after addition of 10 µM NiCl2 to 0.05 mg/mL Cas9-[His6]2 in 30 mM Tris, pH 7.5, 25 °C. (C) Cryo-TEM image of 0.05 mg/mL Cas9-[His6]2 following 10 min incubation in 30 mM Tris pH 7.5 at 25 °C with the addition of 10 mM ZnCl2. Folded sheets/membranes are observed. (D) Cryo-TEM image of concentrated (3.8 mg/mL) Cas9-[His6]2 in the absence of Ni2+ or Zn2+, incubated overnight in 30 mM Tris pH 7.5 at 19 °C. Organized supramolecular structures are not observed, rather disorganized aggregates.
