Single crystal time-lapse measurement using ultrasonic acoustic levitation

We are developing the acoustic levitation diffractometer, a new container-free diffractometer at the Swiss Light Source, Paul Scherrer Institut. By rotating single crystals in an acoustically levitated droplet and collecting the diffraction images by a fast-frame-rate X-ray image detector, the data collection can be completed within a few hundred milliseconds or shorter at room temperature. Here we report time-lapse measurements of ligand soaking using a single crystal. This was achieved by collecting a series of datasets after soaking ligand solution into single lysozyme crystals in a levitated droplet in the acoustic cavity of the diffractometer. Electron density maps of the lysozyme crystals obtained every 30 seconds after the ligand soaking showed meaningful conformational changes around the binding site of the ligand and the radiation damage for 300 seconds after the ligand soaking.