Single-stranded nicks in plasmids

Ashok Aiyar aiyar at
Mon Jul 7 23:10:54 EST 1997

On 7 Jul 1997 17:02:23 -0700,
Kevin Williamson (ksw at wrote:

>I need to know how to introduce a nick into one strand of a ds-plasmid 
>so that I can use ExonucleaseIII to remove the nicked strand- 
>effectively converting a double-stranded plasmid library into a single 
>stranded one for hybridisation.

Does it have to be a specific strand, or will either strand suffice?
If you need the latter, a very long time ago I remember performing a
DnaseI titration until >75% of my DNA was nicked but not degraded - as
estimated by migration on agarose gels.  That will likely work for you
as well.

Ashok Aiyar, Ph.D.
McArdle Laboratory for Cancer Research
aiyar at

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