I've used an even lower-tech method for concentration - hang your dialysis
bag in an air stream (the inlet of a fume hood is good for this) and just
watch the volume drop as the water evaporates through the tubing!
Cheers,
Roger
At 09:07 AM 05-11-98 -0400, you wrote:
> FWD>Hydrolysis protocols; low-tech concentrating_ 11/4/98 15:16
>
>
>Angela-
>
>Many years ago, I was able to very effectively concentrate a protein by
>dialysis against a 10% solution of high molecular weight polyethylene
>glycol. Unlike sucrose, the PEG was just too big to diffuse through the
>pores of the membrane.
>Another low-tech method of concentrating a protein is to pack the dialysis
>tube (containing the protein solution) in dry sephadex. The sephadex will
>"trap" the water diffusing through the membrane pores, thereby concentrating
>the protein.
>
>Vernon
>
>Vernon A. Shoup
>Regeneron Pharmaceuticals
>Rensselaer, NY 12033
>
>(518)488-6012
>vernon.shoup@regpha.com
>
>----------------------------------------------
>Date: 11/04/1998 5:17 PM
>From: Angela c. Murphy
>I too have gotten brown gunk (tar, caramel) from hydrolyzing sugar-
>containing peptides or proteins, but have found that the interference with
>the amino acid analysis really depends on how much carbohydrate is
>there. I routinely do analyses for another lab that does NMR studies of
>DNA-binding proteins, and I am often given a sample of a protein which
>has the DNA bound. These samples do not give any brown or even yellow
>color upon hydrolysis and the analyses are very reproducible. On the
>other hand, people in my own lab have given me protein samples that were
>concentrated by dialysis against sucrose - very messy. The sucrose
>apparently gets through the membrane somehow, perhaps by dissolving in
>the water it is supposed to remove. Has anyone else encountered this
>problem and found a way to get rid of sucrose before hydrolysis?
>Angela C. Murphy
>
Roger Murphy, Ph.D.
Biological Production Facility
Ludwig Institute for Cancer Research
Austin & Repatriation Medical Centre
Studley Road,
Heidelberg, Vic. 3084
Australia.
Tel 61-3-94965463
Fax 61-3-94965436
Email murphy_r@licre.ludwig.edu.au