low resolution of DNA binding protein

From: LISA
Date: 6 January 2012 12:40


Hi all,

I have a DNA binding protein. I get crystals of this protein by co-crystallization with different dsDNAs. But all the crystals have very poor resolution, about 10-20A. I tried to purify protein-DNA complex before setting trays, but it didn't work. Please give me some suggestion. Thanks.

lisa

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From: Ed Pozharski

This is quite common with protein-DNA complexes - they tend to exhibit
disorder.  Obvious suggestions are to look for a better diffracting
crystal form, and this approach includes varying DNA length.  Not sure
if improving crystal quality through dehydration has been tried
extensively for protein-DNA complexes, and frankly I doubt its
potential, but who knows.

But before you throw samples in the sink and curse the darkness, try the
crazy approach of testing ~100 crystals.  Worked for us with the TDG -
average crystal diffracts to 10-20A at a synchrotron, but about 1-2% of
them miraculously go to 3A.  After all, you only need one "good"
crystal.

Cheers,

Ed.

--
Oh, suddenly throwing a giraffe into a volcano to make water is crazy?
                                               Julian, King of Lemurs