Hi,

I have never done this myself, but as far as I know, DNA can be directly 
conjugated through their primary amino groups to CNBr-activated beads or 
NHS-activated agarose beads. These beads are supplied by many companies: 
pierce, sigma, biorad, GE healthcare, etc.. - the same thing used for making 
protein-conjugated beads through amine coupling.

Unmodified DNA works, since the bases contain primary amines. In the early 
days some people just loaded denatured DNA onto CNBr-activated beads and 
then they would react. Here is one of the early papers:
http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1975.tb04151.x/pdf
My idea: if you generate sticky ends with some restriction enzymes or the 
Klenow fragment, it should help exposing the bases on the overhangs, then 
you should not need to denature the DNA and worry about all the crazy ways 
that the DNA sits on the beads.

Having said that, ideally, terminally amine-labeled oligos should be used 
whenever possible, as it is more likely to gives you higher degree of 
coupling and site-specific conjugation. Only one of the two chains needs the 
NH2 label, then the two complementary oligos can be annealed to make a 
one-end labeled dsDNA. When a longer piece is needed, the dsDNA can be 
generated by PCR with one 5'amine labeled primer and one regular primer. You 
can synthesize amine labeled oligos from most oligo synthesis facilities.

Here is a literature discussing such coupling through amine modified oligos:
http://www.plosbiology.org/article/info:doi%2F10.1371%2Fjournal.pbio.0020173#pbio-0020173-g003
Amine coupling is discussed in the part "Oligonucleotide Hybridization 
Chromatography".

Zhijie

>
> --------------------------------------------------
> From: "Alexandra Deaconescu" <[log in to unmask]>
> Sent: Saturday, April 09, 2011 8:44 PM
> To: <[log in to unmask]>
> Subject: [ccp4bb] immobilized DNA resin
>
>>  Hello ccp4 enthusiasts:
>>
>> I am afraid this is a non-ccp4 related question. Can anyone recommend an 
>> immobilized dsDNA chromatographic resin for purification of DNA-binding 
>> proteins? GE seems to have something - I was wondering if people have 
>> other recommendations? In the age of GST and His tags etc., these are not 
>> very much used, but I do not have a tag in this case...
>>
>> Thanks a lot,
>> Alex
>