Millisecond cryo-trapping by the spitrobot crystal plunger simplifies time-resolved crystallography

The authors introduce the spitrobot, a crystal plunger, enabling cryo-trapping with millisecond time-resolution via the liquid application method (LAMA). Ligand binding and reaction intermediates are demonstrated in three different enzymes. We introduce the spitrobot, a protein crystal plunger, enabling reaction quenching via cryo-trapping with a time-resolution in the millisecond range. Protein crystals are mounted on canonical micromeshes on an electropneumatic piston, where the crystals are kept in a humidity and temperature-controlled environment, then reactions are initiated via the liquid application method (LAMA) and plunging into liquid nitrogen is initiated after an electronically set delay time to cryo-trap intermediate states. High-magnification images are automatically recorded before and after droplet deposition, prior to plunging. The SPINE-standard sample holder is directly plunged into a storage puck, enabling compatibility with high-throughput infrastructure. Here we demonstrate binding of glucose and 2,3-butanediol in microcrystals of xylose isomerase, and of avibactam and ampicillin in microcrystals of the extended spectrum beta-lactamase CTX-M-14. We also trap reaction intermediates and conformational changes in macroscopic crystals of tryptophan synthase to demonstrate that the spitrobot enables insight into catalytic events.

Automated summary

The authors introduce the spitrobot, a crystal plunger, enabling cryo-trapping with millisecond time-resolution via the liquid application method (LAMA). Ligand binding and reaction intermediates are demonstrated in three different enzymes. We also trap reaction intermediates and conformational changes in macroscopic crystals of tryptophan synthase to demonstrate that the spitrobot enables insight into catalytic events.