https://www.biorxiv.org/content/10.1101/2023.08.17.553673v1

In this manuscript, we show that the structure of a gas phase protein can be determined at near- atomic (2.6 Å) resolution by cryo-EM. To make this possible we developed a workflow with bespoke hardware: native electrospray ion-beam deposition (ESIBD), consisting of native electrospray ionization, mass selection, gentle landing of the protein ions, in-situ ice embedding, and clean cryo- transfer.

we demonstrate the following key points:

• We present a 2.6 Å cryo-EM density map of the tetrameric protein complex β-galactosidase. This resolution allows us to determine and analyze structural changes on the side-chain level.

• We identify a single dominating gas-phase structure which retains the native secondary and tertiary structure to a high degree.

• We observe compaction of the tetrameric complex, due to closing of cavities and grooves upon removal of water.

• MD simulations identify dehydration as the main driver of the observed structural changes.