On Wed, 2011-07-27 at 13:42 +0100, Charles Allerston wrote:
> I am trying to decide on the many variables I need to consider to
> attempt a co-crystal between a protein I work on and a DNA oligo of
> ~35nt in length.
>
In my somewhat limited protein:DNA crystallization experience, the "less
pure" oligos are just fine. I suspect that protein:DNA complex
crystallization is just like protein crystallization - every system is
different and whatever worked for someone in the past may not be
applicable in your case. Basic rules are (may the protein:DNA
crystallization experts correct me and expand the list):
1. Keep the DNA length close to whole number of turns.
2. Try blunt ends, single and double overhangs.
3. Slight DNA excess.
4. May try less purified (and thus cheaper) DNA first.
Some anecdotes:
1. Everyone knows complex can be purified, but it is rarely done.
2. Screens "designed" to crystallize protein:DNA complexes are a hoax.
3. Bet on PEG!
4. Don't give up on 10A resolution - just shoot ~1000 crystals and one
will give you a nasty twinned 3A dataset.
Cheers,
Ed.
--
Oh, suddenly throwing a giraffe into a volcano to make water is crazy?
Julian, King of Lemurs
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