Thermal Denaturation of Proteins

Louis Hom lhom at OCF.Berkeley.EDU
Thu May 6 11:15:53 EST 2004

In article <34a4f456.0405060742.2b218479 at posting.google.com>,
Curious <curious11112001 at yahoo.com> wrote:
>The protein changes shape when thermally denatured. Is it correct to
>say all structures excluding the primary are altered?

	I would say "Not always" because the degree of denaturation may
depend on how hot it is, plus things like disulfide bonds can help hold
low order structures intact.  Actually, higher order too I guess (think
about boiling an antibody sample for SDS-PAGE without any reducing agent).

>I have heard that the proteins in the cells hyperthermophilic microbes
>are safe from denaturing even in boiling hot temperatures. The highest
>survival temperature recorded was 113 degrees Celsius. What is the
>mechanism behind this?

	There are a variety of tricks that cells use (e.g., prolines in 
more hairpins).  The strategy seems to be not so much to make the folded 
form more stable, but to make the unfolded state less favorable (the 
prolines, for example, can decrease the entropic gains of unfolding).

Mind you, these are just some minor details I've latched onto.  There's a 
lot more going on that I have long forgotten.
Lou Hom >K'93			     
lhom at ocf.berkeley.edu		

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