[Protein-analysis] Re: Mechanism Of Cold Denaturation

Protenger via proteins%40net.bio.net (by yellowish At gmail.com)
Tue Jan 16 05:30:33 EST 2007

Dr Engelbert Buxbaum wrote:
> Protenger wrote:
> > Hi all
> > I'm confused about cold denaturation, I read "cold denaturation of
> > proteins" by privalov, but beside
> > thermodynamics explanation of this phenomenon there must be molecular
> > mechanism by which this type of denaturation can be described.
> > I would be appreciated if anybody give simple description of
> > thermodynamics concept of this event
> > but also molecular mechanism of that.
> The bond energies of the various interactions that are responsible for
> secondary and tertiary structure are energy dependent, as is the motion
> of the atoms that make up proteins. The temperature coefficients however
> are different, so that bonds become dominating at one temperature, which
> are not dominating at another. As a result in the cold the structure of
> lowest free energy may be different from that at 37 degrees. Especially
> if you cool slowly, thus allowing the new structure to be achieved
> (anealing). Cooling quickly may trap the protein in the higher
> temperature structure, since the mobility drops with temperature. That's
> why we snap-freeze our samples.

Thanks for your help, but what is the reason of weakened hydrophobic
interactions at low temperature (in spite of lower entropy), and what
is the role of whater molecules in destabilizing native structure
( indeed destabilizing hydrophobic interactions) of proteins in cold
denaturation event?
Thank You

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