Easiglow cleaning system

Solutions containing 100 μM
E₄₀^S–S₁₀^Q or E₈₀^S–S₁₀^Q and incubated
for 16 h at room temperature were prepared
for cryo-TEM. The cryo-TEM measurements were performed at Duke University’s
Shared Materials Instrumentation Facility. First, lacey holey carbon
grids (Ted Pella) were cleaned in a PELCO EasiGlow cleaning system
(Ted Pella). For each sample, 3 μL was deposited onto a grid.
Samples were then vitrified using a FEI Vitrobot Mark III by blotting
the sample for 3 s with an offset of −3 mm and vitrifying it
in liquid ethane. To prevent sample evaporation prior to vitrification,
the sample chamber was kept at 22 °C and 100% humidity. Finally,
the prepared grids were placed into a Gatan 626 cryoholder and imaged
on a FEI Tecnai G2 Twin.

Cryogenic transmission electron microscopy (cryo-TEM) was performed at Duke University’s Shared Materials Instrumentation Facility (Durham, NC). Lacey holey carbon grids (Ted Pella, Redding, CA) were glow discharged in a PELCO EasiGlow Cleaning System (Ted Pella, Redding, CA). A 3 µl drop of a sample was deposited onto the grid, blotted for 3 seconds with an offset of −3 mm, and vitrified in liquid ethane using the Vitrobot Mark III (FEI, Eindhoven, Netherlands). Prior to vitrification, the sample chamber was maintained at 22 °C and 100% relative humidity to prevent sample evaporation. Grids were transferred to a Gatan 626 cryoholder (Gatan, Pleasanton, CA) and imaged on a FEI Tecnai G2 Twin TEM (FEI, Eindhoven, Netherlands).