The Rock Imager 1000 in our lab has a current storage capacity of 250 crystallization plates, operates at 20°C with humidity control and features various imaging modes (Visible light, UV, Multi-Fluorescence). The imaging options come with several automated features, including extended focus imaging (EFI) – important for maintaining high resolution and high depth of field. High resolution means that you have a lower depth of field when imaging drops, so the entire drop will not be in focus at the same time. To achieve high optical resolution and high depth of field, Rock Imager captures several images at different Z-heights (slices) and computes an image that contains the best-focused pixels from each of the slices.
- Visible Light Imaging: The standard imaging technique for screening used by most crystallographers.
- Ultraviolet (UV) Imaging: Protein crystallization drops are illuminated with UV light and the fluorescence emitted by aromatic amino acids like tryptophan are detected to create an image. If no fluorescence is detected within a crystal, then it lacks aromatic amino acids to produce a signal and is likely not protein.
- Multi-Fluorescence Imaging (MFI): This mode of imaging uses up to 3 different wavelengths, including UV and visible fluorescence. By labelling the protein with a fluorophore, it is easy to find hidden protein crystals that might be buried under precipitate and discriminate them from salt crystals, even for proteins with little-to-no tryptophan. Also, this technique allows the differentiation between crystals of a protein-protein complex and crystals of a single protein.
