Reply to "cDNA size selection columns"

[James Hartley]

Bruno,

	An easier way is to add 1/2 volume of 30% PEG 8000 (Sigma), 1.8 M NaCl to 
your cDNA, mix well, centrifuge immediately 10 min at RT, discard the sup 
which contains everything smaller than ~200 bp, dissolve the ppt (often 
invisible, it forms more of a film than a pellet).

	If you want to check the procedure out first, take a DNA marker with small 
bands, run this protocol.  See also 
http://www.invitrogen.com/Content/Focus/181027.pdf.  I switched to NaCl 
instead of MgCl2 to make it easier to dissolve the ppts.  If you use MgCl2 
I think you need to dissolve in TE, the EDTA will chelate the Mg, for NaCl 
any aqueous solvent will do.

Jim Hartley
James L. Hartley, Ph.D.
Director, Protein Expression Laboratory
SAIC / NCI
Frederick, MD 21702
301 846 7375
Fax 301 846 7390
hartley at ncifcrf.gov

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