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clean-up of ssDNA

Jim Owens jow at helix.nih.gov
Thu Aug 5 16:17:09 EST 1993

>  I have isolated mg quantities of ssDNA following the protocol of
Gruber et
>al in Focus 15: 59-65.  I have a problem in that the OD 260/280 is about
>after following the full protocol. I need to quantify this material
>as well as having very clean ssDNA.
>  Does anyone have any quick solutions for a cleanup of this large
amount of
>material.  In the protocol, multiple phenol-chloroform  extractions have
>already been performed.
>  If there is a FAQ to this point could someone direct me to it.
>Tom Newman

Residual phenol is a good source of 280nm absorption as would residual
tyrosine and tryptophan (phenylalanine has maximum absorption at 257nm). 
I would try dialysis on the shiny side of a Millipore VMWP 02500 membrane
(50nm pore size) floating on TE in a petri dish with or without another
EtOH precipitation.

Another possibility is to call the authors at BRL (800-828-6686).  I
noticed that they only claim a yield of 0.5 to 1mg per liter of LB.

Good luck,

Jim Owens

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