Poor resolution when isolating ssDNA?

Evan Reed via methods%40net.bio.net (by evan.g.reed from gmail.com)
Thu Jun 12 16:56:35 EST 2008


		I am trying to isolate ssDNA after binding dsDNA oligos with  
biotinylated antisense strands to strep microbeads, denaturing with  
NaOH, then adding the supernatant containing the sense ssDNA to a  
NAP-5 sephadex desalting column.  Unfortunately, I am getting terrible  
resolution when I try to elute on the column -- even after 2 mL of  
elution, I am still getting detectable levels of ssDNA in the eluate  
(dsDNA oligos of the same length elute just fine in 0.5 mL, with  
acceptable resolution).  The amount of DNA loaded into the column  
should be well below the binding capacity so I am not sure why this is  
happening.  Has anyone done this before?  Is there a better way to  
purify the ssDNA instead of this column?



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