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Re: [ccp4bb]: cryo-protect crystals grown in 35% dioxane
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To decrease the mosaicity you might want to try increasing the cryo
concentration even further - say 35-40% PEG400 in your case. You can do it
in steps of concentration (going from your condition to 30% then 35-40,
slowly to avoid cracking the crystals...)
On Mon, 27 Nov 2000, Hong Zhang wrote:
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> Hello, everyone,
> I sincerely appreciate everybody who extended their help to me in this case.
> I've tried most of the suggestions I received, and here is a breif summary:
> 1. Dioxan alone: crystals start melting after a few seconds in 35%-70%
> dioxane (+little buffer and salt presented in protein buffer). I put a
> crystal washed in 70% dioxane in the cold stream, and it looked a bit
> cloudy. I didn't get to collect any frames due to a stupid mistake.
> 2. 35% dioxane + various glycerol: crystal melted pretty fast.
> 3. 35% dioxane + 25% ethylene glycol or MPD: crystals start melting after
> more than a few seconds. But I manage to freeze them before they gone bad.
> These crystals are yet to be tested in the beam.
> 4. 35% dioxane + 25% PEG400: I am currently collecting data on this crystal!
> The crystal is stable for up to 5min in this solution. A few second wash
> provided good cryoprotection (no ice rings), but mosaicity is a quite high
> That's all!
> Hong Zhang
> Department of Biochemistry
> University of Texas Southwestern Medical Center
> 5323 Harry Hines Blvd.
> Dallas, Texas 75390-9038
> Phone: 214-648-9299
> Fax: 214-648-9099
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