concentration of low molecular weight protein

Hiranya Roychowdhury hroychow at NMSU.EDU
Sat Sep 20 12:52:04 EST 1997

At 10:53 PM 9/19/97 GMT, Stephen C. Dahl wrote:
>Damn this server....somebody wrote:
>: How do I concentrate a low molecular weight protein (less than 5kDa)
>: from gel filtration fractions ie. dilute???, keeping in mind that
>: filtration devices and dialysis tubing concentrate above this size.
>One option which I've used on a limited basis (and have never taken the
>time to quantify the results) is to swell a powdered gel filtration
>medium--in your case Sephadex G10 or G15--in your pooled fractions.  The
>beads take up the water and, in general, exclude your protein if you
>choose your matrix wisely.  Good luck.
>Steve Dahl

I wonder if extracting the protein solution with something like n-butanol
will do the trick too. I have used it to concentrate DNA solutions. But
then, some proteins may ppt in that solvent. If this one doesn't, then
surely n-butanol extraction is worth a try. The other alternative is to use
a volatile buffer (eg. bicarbonate) in protein elution and then to
freeze-dry the sample. 

Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu

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