Data collection: Tips and Tricks

From CCP4 wiki
Revision as of 09:36, 15 February 2009 by Kay (talk | contribs) (rearrangement and links)
Jump to navigationJump to search

See also cryo and Crystal growth: Tips and Tricks#Reducing the mosaicity, and Improving crystal quality.

The following tips mostly refer to cryo improvement:

  • 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 for cryoprotection
  • 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 (often growth faults lead to end of crystal growth)
  • use a synchrotron beam (as it is less divergent than the usual home source, and the apparent mosaicity is the sum of the crystal mosaicity and the crossfire)
  • shoot at parts of the crystal to find if there are good and bad parts (this requires a small beam)