Lambda DNA resists digestion

Tom Beals tomb at
Wed Nov 2 00:00:17 EST 1994

In article <396aas$ki1 at>, rmauk at (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

More information about the Methods mailing list