matrix for spin columns

[David Micklem]

In article <5hbmpr$i6i15 at ncisun1-nf0.ncifcrf.gov>, pnh at ncifcrf.gov (Paul N
Hengen) wrote:


>
>Try Sephadex G-50 (cut-off is ~ 30,000 MW). The MW of a 50 nt PCR product will
>be close to 30,000 if it is 0% CG or 100% GC (all A's or all C's).  If you find
>it too close for the cut-off try Sephadex G-25. You can get it from Sigma (see
>page 1813), or you can buy pre-loaded push columns from other biotech companies
>like Stratagene...very convenient.
>
>Using the dnamwt program gives you the MW of the PCR product,
>
>All A's:
>
>dnamwt 1.08
>the number of A's in strand 1 of the sequence is: 50
>the number of C's in strand 1 of the sequence is: 0
>the number of G's in strand 1 of the sequence is: 0
>the number of T's in strand 1 of the sequence is: 0
>total number of bases:         50
>strand 1 molecular weight: 15678.0 daltons
>strand 2 molecular weight: 15228.0 daltons
>total molecular weight: 30906.0 daltons
>% GC:  0.0
>
<snip!>

Hi Paul,

Is this approach OK for DNA?  I'd always assumed that the cut-offs were for
roughly spherical molecules, which PCR products/oligos probably aren't...

David

-- 
D.R.Micklem,                                Time flies like an arrow... 
Wellcome/CRC Institute,            Fruit flies like a banana.       
Cambridge CB2 1QR, UK               Tel: [+44] (0)1223 334129
Email:drm21 at mole.bio.cam.ac.uk Fax: [+44] (0)1223 334089