Size-selection of cDNA: method?

[C Coward]

Greetings!

I have a cDNA library that has rather too many small inserts. I still have
some of my cDNA substrate I used for the ligaiton, but not a lot of it
(ca. 100ng). Ideally I'd like to separate out the short cDNA molecules -
say retaining everything over 400 bp. I could obviously do this via gel
extraction, but I'd rather not go that route for fear of ending up with
too dilute a product.

So.....what I'm after is a method (or suggestion of commercial
size-exclusion columns) for removing DNA <400 bp from a small volume
(currently I'm in 30 ul, and ideally wouldn't go up to more than 50 ul).
Ideally I'd be able to get the <400 bp stuff back as well, but that's of
lesser importance.

Any suggestions?

Cheers in advance

Chris

--  
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Dr. Chris Coward                       | Tel: +44 1223 333976
University of Cambridge                | Fax: +44 1223 333992
Department of Genetics                 | E-mail: cc122 at mole.bio.cam.ac.uk
Downing Site, Cambridge                |        
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England                                |
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