X-Message-Number: 8690
From: James <>
Newsgroups: sci.cryonics
Subject: Re: on changing the freezing point of water by pressure
Date: Tue, 21 Oct 1997 22:19:00 -0500
Message-ID: <>
References: <> <>

> For example how resistant can a protein molecule become at
> minus 30 or 40 degrees or more depending on how much pressure you can
> use to keep the water from freezing , without the pressure causing a
> problem 

You'll probably have to go to the priamry literature for this one.  I
don't have any figures for how much pressure causes how much of a change
in freezing point, so I can't compare it with the pressure figures that
would be denaturing (that can be found in research dealing with using
high pressure to sterilize foods for canning - creative searches should
lead you to a bit of info on that).

> learn more , Also you don't happen to know about how stable are
> protein's at very low temps when plunged into such things as anhydrous
> alcohol's or etc. but are completely removed from them before the
> temperatures are brought up ? Also I may try a web search on anything
> relating to liquid CO2 .there must be more info on it someplace and its
> water resembling properties to help segest if it has any chance at all
> ,of some mixture of it being a cryoprotectant to replace water in cells,
> a longshot of course.

Most proteins are probably pretty stable in -OH.  Water is a big
disrupting force in protein folding as it competes with other parts fo
the protien for hydrogen bonds.  SO, alcohols probably actually make
most proteins more stable.  But, the problem seems to me to be that
there will certainly be exceptions.  Even if you destroyed one in 100 of
your enzymes, you'd be in a heap of trouble.  Also, while OH might be
good for proteins, it would be very bad for membranes.  They rely on
hydrophobic interactions to maintain their structure.  And, for -OH or
CO2, how are you going to get the water out and the other thing in
without causing structural damage?  Hate to be a killjoy, but there are
a lot of problems with every idea out there...  or else everyone would
do it :)

If you want to research something and look into new ideas, the track I
would suggest is a non-toxic permeable cryoprotectant (DMSO comes to
mind, but I'm sure there are reasons it doesn't work since everyone
knows about it).  What we need is a substance that would cross cell
membranes readily, is not toxic in the necessary concentrations, and
intercalates between water molecules in such a way that this water/new
substance "ice" have virtually no coefficient of expansion as it
freezes.  It's just as much of an engineering problem as it is a
biological one.  I wouldn't doubt that such a substance exists and we
just haven't thought of it yet.

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