Retrieval of ssDNA from a mixture of ssDNA/dsDNA

[Allen Gathman]

In article <3k4d8c$mim at mserv1.dl.ac.uk> jsasse at hgmp.mrc.ac.uk (Mr. J. Sasse) writes:
>
>
>Hello netters,
>I would like to separate and retain ssDNA from a mixture of ssDNA and
>dsDNA which is in aqueous solution. The ssDNA I particularly want to keep
>is a 50-55mer. Does anybody have any ideas?
>Jurgen
>
>Jurgen Sasse                 email:js1 at mole.bio.cam.ac.uk
>Dept. Pathology                Tel:01223/333718
>Cambridge Univ.
>Cambridge, UK
>e
>.
>.
How about using a small hydroxyapatite column? Hydroxyapatite binds
dsDNA more strongly than ssDNA; ssDNA elutes at 60 degrees in .12M
phosphate, while dsDNA elutes at the same temp in .3M phosphate.
See, maybe, Britten et al 1974, Methods in Enzymology 29E:363-406.

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