Enzyme to digest dsDNA in ss/ds mix

Aawara Chowdhury aawara at nohome.org
Thu Jan 19 11:06:52 EST 2006

In <1137686706.707987.247560 at o13g2000cwo.googlegroups.com>,
 Susan Hogarth <hogarth at gmail.com> wrote:

> Nick Theodorakis wrote:
>> On 18 Jan 2006 15:37:40 -0800, "Susan Hogarth" <hogarth at gmail.com>
>> wrote:
>> >Is there an enzyme which will digest dsDNA in a ss/ds mix?
>> >
>> Exonuclease III might be suitable for your needs. What is your
>> substrate(s) do yo have and what products do you need?
> I have the products of an asymmetric PCR, and want only the ss product
> (or at least to enrich it in proportion to the ds product.

If you used Taq (or any enzyme without proofreading ability), exoIII will
not digest the dsDNA PCR products, because Taq adds a 3' non-templated
nucleotide (usually dA) at the end.  exoIII only acts from blunt ends or
5' overhangs.

In America, through pressure of conformity, there is freedom of choice,
but nothing to choose from - Peter Ustinov.

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