Fiona,
Two suggestions.
1. When you crystallize protein/DNA complexes, one of your most powerful
parameters is to change your DNA, either the lenght of it or the sequence
(presumably outside the recognition sequence to which your protein(s) bind).
So, repeat with slightly different DNA.
2. You write that after a long time of waiting, your crystallization behavior
might be different. I would check the protein after long term storage,
specifically - if the protein permits - try to run an IEF gel. Quite often
proteins deamidate upon long term storage. If that is the case, you can get
some ideas on what to change to make bigger/better crystals.
Mark
-----Original Message-----
From: [EMAIL PROTECTED]
To: [email protected]
Sent: Thu, 23 Nov 2006 1:14 AM
Subject: [ccp4bb]: co-crystallization skin and microcrystals
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Hello All,
I'm attempting to co-crystallize a dimeric transcription factor bound to DNA
and see skin formation and microcrystals at even the lowest concentration of
precipitant that I have tried. The complex crystallizes (I believe) on storage
at 4 deg, but these crystals do not diffract. I have additionally tried using
increased concentrations of reducing agents and also covalent modifications of
Cys residues and still see skin formation. After long term storage, larger
crystals grow after a few months storage, but are leaf shaped and growing in
clumps. I have not checked the diffraction limits of these crystals as yet (no
access to local x-ray source).
Any advice as to how to control the seeding events and/or skin formation would
be appreciated.
Thanks!
Fi
Fiona Whelan
Whitelaw Lab
School of Molecular and Biomedical Science (Biochemistry)
The University of Adelaide
Phone: 8303 4806
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