3D ED tilt series of Argyrin D

The electron diffraction tilt series (3D ED) was collected in continuous rotation mode using the dedicated TEM-controlling script (Gorelik at al., 2021). 

The sample was ultrasonically dispersed in EtOH. A drop of the suspension was placed onto carbon-coated TEM cupper grid. 3D ED data were collected using a Thermofischer TALOS TEM, operated at 200kV (Ulm University). The data were collected at liquid nitrogen temperature. Dry sample was inserted into the TEM and then cooled – no cryo-transfer procedure was applied. Cryo-transfer sample holder allowing for high-tilt goniometer rotation was used. Electron diffraction was performed in nanodiffraction mode with condenser C2 aperture of 50 microns. The effective beam diameter on the sample was about 7 microns. The sample was scanned with the electron dose rate of 0.003 e/A2s, electron diffraction patterns were collected with the dose rate of 0.03 e/A2s. A single dataset within a tilt range of -70…70° containing 118 frames, had a total accumulated dose of 3.5 e/A2. Binning 4 of the CETA camera was used, camera length was 1.35m, resulting in the pixel size of 0.00166 A-1 of 1024x1024 frames, corresponding to the effective detector distance of 1,344 mm. Single frame exposure was 1 second, relative goniometer rotation speed 0.04, resulting in the effective oscillation range of 1.18°.

The lateral crystal size was ca. 1.5 micron x 6 micron.

Gorelik et al., 2021. Acta Cryst. B77, 662–675.