Re: [ccp4bb] Cryo-protectant

[Joe]

Title: Re: [ccp4bb] Cryo-protectant

First of all, you need to find out if crystals you grew have similar quality before you conclude poor diffraction is due to cryoprotectant solutions. As others have suggested, you can test crystals using capillary mounting method. Second, there are a lot more cryoprotectant agents out there you can try. Not sure why you sticked to MPD, which is not even present in your crystallization condition. One of protein crystallized in almost the same condition as yours. What I did is just simply increasing % PEG3350, in addition to 10%-15% increment of every other ingredients (your protein buffer + well solution). I also introduced 5% glycerol to bring down % PEG3350. You can play around % PEG3350 and % glycerol to find a  fine combination that is cryo-clear and makes you crystals happy. Joe Liew Chong Wai wrote: Hi all   Thanks for your precious suggestions and ideas. The crystallization buffer condition is 0.1M BIS-TRIS pH 5.5, 0.2M MgCl.6H2O, 35% PEG3350 Now, my crystal seem ok in 20% ethylene glycol, but only after a couple minutes of dehydration at room temperature. For sure, i will try other cryoprotectant that was suggested here. I just wondering why MPD kills the crystal. Many thanks   LIEW