Difference between revisions of "Data collection: Tips and Tricks"

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(New page: == 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 ...)
 
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== [[cryo]] ==
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See also [[cryo]] and [[Crystal growth: Tips and Tricks#Reducing the mosaicity]], and [[Improving crystal quality]].
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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.
 
* 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
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* Try oils for cryoprotection
* Try stepwise increase from low concentrations of cryoprotectants to the required concentration, over several minutes/hours/days.  
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* 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.
* The larger the crystal, the longer should be the incubation in each step.
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* Small crystals often do better in terms of mosaicity increase than big crystals (often growth faults lead to end of crystal growth)
* Small crystals often do better in terms of mosaicity increase than big crystals.
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* 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)
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* shoot at parts of the crystal to find if there are good and bad parts (this requires a small beam)

Revision as of 09:36, 15 February 2009

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)