Gary Dossantos gary at NODULE.MCGILL.CA
Fri Nov 29 13:34:19 EST 1996

> From: David Bird <birdd at>
> Subject: Phenol
> Date: Wed, 27 Nov 1996 23:25:27 -0700
> Okay so Phenol inactivates and precipitates out protein. How is it
> done? Does the hydroxyl of the phenol attack side chain amino groups
> (his, lys, etc.), binding up the protein with hydrophobic molecules?
> Does anyone know?
> -Dave

I believe that it is a physical process as opposed to a chemical
process: The proteins fold initially in order to minimize their free
energy. In a polar medium such as water, this means that hydrophobic
groups are directed into the middle of the protein, away from the water.
When phenol is added, the proteins are placed in a non-polar medium.
This causes the proteins' hydrophylic surface groups to aggregate
together (to minimize their free energy) and the hydrophobic interior
groups to turn to be exposed to the surface. The net effect is an
unfolding of the proeins. However, there is now a problem of hydrophylic
groups in a hydrophobic environment. To deal with this, these groups
from all the different proteins aggregate together, increasing their
mass and precipitating out.

Gary DosSantos

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