Pinpointing Protein Crystal Structures over a Broad Temperature Range Using Hydrophobic Protection.

Protein interactions are dynamic processes that are influenced by chemical and physical variables. While variable temperatures play an important role in understanding biological processes, their use in protein crystallography has been limited because of the loss of diffraction power. Here, we report the selection of a cryoprotectant that enables X-ray diffraction data collection across a temperature range from cryogenic to room temperature. Although several hydrophobic materials effectively preserved samples at 100 K, only a few compounds allowed for data collection at 300 K. We identified hydrophobic greases suitable for both home-source and synchrotron applications, supporting fast and slow diffraction, with long exposure times at atomic resolution. Data collected between 100 and 300 K showed no significant effect of exposure time (ranging from 70 ms to 1 s) but revealed an exponential temperature dependence on the overall B-factor. These findings highlight the importance of hydrophobic grease in crystal protection against variables, such as temperature and dehydration, enabling optimized data collection across a wide temperature range.