Lambda DNA resists digestion

Tom Beals tomb at biology.lifesci.ucla.edu
Wed Nov 2 00:00:17 EST 1994


In article <396aas$ki1 at news.service.uci.edu>, rmauk at crick.bio.uci.edu (Rob
Mauk) wrote:

> I have isolated lambda gt10 DNA by PEG precipitation followed by organic 
> extraction and ethanol precipitation, and find that it is almost 
> completely resistant to digestion by EcoRI and all other enzymes that I 
> have tested.  Proteinase K treatment did not help, nor did additional 
> extractions and precipitations.  Plasmid DNA digests normally with these 
> enzymes, but if the plasmid is mixed with the lambda DNA, it is rendered 
> undigestable.  Any comments or suggestions regarding the nature of this 
> contaminant, or solutions to the problem would be greatly appreciated.  
> Thank you.

Was it a plate lysate?  If so, did you use agar?  If so, in my experience that
DNA will never cut (sulfonated polysaccharides from agar?).  Make plates from
agarose.



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