Formvar and carbon coated copper

$\mathrm{P}\mathrm{R}{\mathrm{D}}_{\mathrm{703}–\mathrm{868}}^{\mathrm{S}\mathrm{t}\mathrm{r}\mathrm{e}\mathrm{p}}$ samples, ∼1.2 mg/ml, were incubated at 30 °C in 20 mM sodium phosphate, pH 7.0, 50 mM NaCl, 1 mM TCEP, and 1 mM EDTA. Aggregated samples were subjected to sonication (∼10 min; Elmasonic P ultrasonic bath) and diluted to ∼0.2 mg/ml immediately before application to the TEM grids (400-mesh formvar and carbon-coated copper; Electron Microscopy Sciences; catalog no. FCF400-Cu). About 1 min after deposition, the sample solution was wicked with filter paper, followed by a quick wash with 3 μl of water and the addition of three to five drops of 2% w/v aqueous uranyl acetate solution. The uranyl acetate was wicked immediately with a filter paper, and the grids were air dried at room temperature. TEM images were acquired using a JEOL JEM-1400Plus transmission electron microscope (JEOL) and recorded on a Gatan OneView digital camera (Gatan).