Hi Deliang,

I have an experience with soft crystals:

I used to work with a protein which crystallized fine and diffracted fine. However, after opening the crystallization well few times, crystals turned soft and they stopped diffracting. If I remember correctly, letting crystals sit for a long time (without opening the wells) also caused “softening” of crystals. I suspected polymerization but did not experiment with it. Adding huge amounts of reducing agent helped preserve the “hardness” of crystals little longer. Transferring the crystallizations experiments into the cold room also helped.

Bottom line is that soft crystals didn’t diffract.

Good luck,

Nukri

Ruslan Sanishvili (Nukri), Ph.D.

GM/CA-CAT, Bld. 436, D007
Biosciences Division, ANL
9700 S. Cass Ave.
Argonne, IL 60439

Tel: (630)252-0665
Fax: (630)252-0667
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From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of deliang
Sent: Friday, November 14, 2008 3:28 PM
To: [log in to unmask]
Subject: [ccp4bb] off-topic: soft crystals?

Hi there,

Do you ever have experience with the diffraction quality of soft crystals? I just harvested some. They are 30K membrane protein, growing 10 months, size ~0.6mm*0.2mm*0.02mm, but as soft as a hair, no sharp surfaces.

We don't have synchrotron time in a few months and no experience with such crystals. Right now we need to decide whether we should use similar conditions for further screening or should change completely methods(from sitting drop to lipid cubic phase), and detergents. Any comments about your work with soft crystals are really helpful. Many thanks.

Deliang