Some things that are a good sign for having DNA as well as protein in your
crystal:
1) You get different (or no) crystals if you add or substract a base or two
from the DNA ends. Of course, we did get fooled by this logic once when one
particular oligo seemed to be contaminated with an easily crystallizable
mystery salt.
2) Unusually intense spots at ~3.4A, usually in the best direction of
diffraction (due to the spacing between bp). If the DNA is a reasonable
fraction of your scattering mass, it may be quite noticeable with hklview.
3) Anisotropic diffraction, often to far lower resolution than you'd hoped for.
Also note that fragile hexagonal crystals might be DNA-only. Especially if the
person setting up the trays tells you they were optimized by increasing the
DNA:protein ratio ;-).
Good luck!
Phoebe
=====================================
Phoebe A. Rice
Dept. of Biochemistry & Molecular Biology
The University of Chicago
phone 773 834 1723
http://bmb.bsd.uchicago.edu/Faculty_and_Research/01_Faculty/01_Faculty_Alphabetically.php?faculty_id=123
http://www.rsc.org/shop/books/2008/9780854042722.asp
---- Original message ----
>Date: Sat, 1 Oct 2011 11:36:59 +0800
>From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> (on behalf of zq deng
><dengzq1...@gmail.com>)
>Subject: [ccp4bb] detect dsDNA
>To: CCP4BB@JISCMAIL.AC.UK
>
> Hi all,
> .
> recently,I got a crystal of protein-DNA crystal.i
> used silver stainto prove that it is a protein
> crystal.Does anyone have method to detect if there
> is DNA in the crystal.
> any suggestion will be appreciated.
>
> Regards,
> deng
