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Your crystal is very mosaic etc. The 1st step is to take a still diffraction image to check whether the freezing damaged the crystals or the crystals grew poorly in the 1st place.
There are many approaches to try and improve crystal quality, but they all share the same characteristics:
- they work in a few cases and not in many others
- What is going to work in a new case is typically unpredictable
Considering your crystallization conditions, one suggestion (and I mean one of many) is to vary the cation (Mg2+ Ca2+ etc) concentration and look at some more (Mn2+ Zn2+ etc.)
Other good tips can be found in the CCP4 wiki :
http://strucbio.biologie.uni-konstanz.de/ccp4wiki/index.php/Main_Page
I’ll add one : use one of the tennis racket shaped loop if your crystal grow as a thin plate, and either one of these or an elliptical loop if the crystal is needle-shaped. This has made a world of difference if a few (see above) cases I’ve worked on ….
Good luck
Thierry
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Prerana G.
Sent: Wednesday, January 20, 2016 12:03 AM
To: [log in to unmask]
Subject: [ccp4bb] Poor resolution of protein crystal
Dear all,
I have a question on how to improve the resolution of protein crystals. I am working on a protein which crystallizes in the following conditions
1) 0.1M Magnesium nitrate hexahydrate & 10% PEG 3350
2) 0.2M Calcium chloride dihydrate & 6-14% PEG 3350
3) 0.2M Calcium acetate hydrate & 6-14% PEG 3350
The crystals diffracted to a very low resolution (~ 4 Angst, kindly see the attached image) at home source. To prevent ice formation, different cryoprotectants such as glycerol, 2-methyl-2,4-pentanediol, PEG 400, PEG 3350, Hexanediol, were used.
Any suggestion to improve the x-ray diffraction resolution will greatly help me.
Thanking you.
Prerana
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