Data collection: Tips and Tricks

cryo

• PEG3350 seems to be little too large for freezing, particularly in presence of high salt concentration. However, PEG2000 is good enough as a cryo protectant.
• Try oils
• Try stepwise increase from low concentrations of cryoprotectants to the required concentration, over several minutes/hours/days.
• The larger the crystal, the longer should be the incubation in each step.
• Small crystals often do better in terms of mosaicity increase than big crystals.