PVPP cleaning

Dr. Peter Gegenheimer pgegen at ku.nolospamare.edu
Sun Jul 22 14:27:25 EST 2001


On Sun, 22 Jul 2001 11:26:45, Michael Witty <mw132 at mole.bio.cam.ac.uk>
wrote:

| Dear All,
|         I plan to make a big column of PVPP to clean the phenolic
| compounds from a tobacco extract.  If  I want to save money on PVPP and
| more importantly personal effort making columns, how should I clean the
| column after use?
|    Am I right to think that PVPP binds phenolics by hydrogen bonding?
| Should I disupt phenolic compound binding with methanol?  or methanol
| plus 10% acetic acid?
|
| Regards, Mike

Phenolics are thought to bind proteins via H-bonding to the carbonyl
oxygens of the peptide bond, so PVPP (a poly-alcohol) would be a protein
mimic that also binds phenolics.

I do not know what a "column" of PVPP might be -- PVPP ("high mol wt")
is a powder which, when you added a protein extract, would turn into a
gummy mess.  One normally sequesters phenolics by adding PVPP to the
extraction buffer. And, because PVPP is dirt-cheap whereas phenolics are
nasty *#%$!, you want to mess with the PVPP-phenolic complex as little
as possible.

Another procedure which has worked for some in removing inhibitory
flavonoids and perhaps tannins, etc., is to run the extract over a gel
filtration column (Sephadex G-50 or equivalent).

More information on plant extracts can be found in Meth Enzymol 182,
174-193 (1990). There are more recent reviews which I don't have
indexed... there's also a lot of literature on the subject from plant
systematicists who assay isozymes, and plant biochemists/molecular
biologists who have to assay reporter genes in crude leaf extracts.

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