X-Message-Number: 10377
Date: Thu, 3 Sep 1998 13:44:34 -0700 (PDT)
From: Doug Skrecky <>
Subject: vitrification and anhydrobiosis 

  Crowe JH.  Carpenter JF.  Crowe LM.
  Section of Molecular and Cellular Biology, University of California, Davis
  95616, USA. jhcrowe:ucdavis.edu
  The role of vitrification in anhydrobiosis. [Review] [86
  Annual Review of Physiology.  60:73-103, 1998.
  Numerous organisms are capable of surviving more or less
  complete dehydration. A common feature in their biochemistry is that they
  accumulate large amounts of disaccharides, the most common of which are
  sucrose and trehalose. Over the past 20 years, we have provided evidence that
  these sugars stabilize membranes and proteins in the dry state, most likely
  by hydrogen bonding to polar residues in the dry macromolecular assemblages.
  This direct interaction results in maintenance of dry proteins and membranes
  in a physical state similar to that seen in the presence of excess water. An
  alternative viewpoint has been proposed, based on the fact that both sucrose
  and trehalose form glasses in the dry state. It has been suggested that glass
  formation (vitrification) is in itself sufficient to
  stabilize dry biomaterials. In this review we present evidence that, although
  vitrification is indeed required, it is not in itself
  sufficient. Instead, both direct interaction and
  vitrification are required. Special properties have often
  been claimed for trehalose in this regard. In fact, trehalose has been shown
  by many workers to be remarkably (and sometimes uniquely) effective in
  stabilizing dry or frozen biomolecules, cells, and tissues. Others have not
  observed any such special properties. We review evidence here showing that
  trehalose has a remarkably high glass-transition temperature (Tg). It is not
  anomalous in this regard because it lies at the end of a continuum of sugars
  with increasing Tg. However, it is unusual in that addition of small amounts
  of water does not depress Tg, as in other sugars. Instead, a dihydrate
  crystal of trehalose forms, thereby shielding the remaining glassy trehalose
  from effects of the added water. Thus under less than ideal conditions such
  as high humidity and temperature, trehalose does indeed have special
  properties, which may explain the stability and longevity of anhydrobiotes
  that contain it. Further, it makes this sugar useful in stabilization of
  biomolecules of use in human welfare. [References: 86]

Additional note by poster:

  Practical application of anhydrobiosis on human organ systems at present
can not use sugars because of their very poor penetration ability. Animals
which can enter anhydrobiosis have special sugar transporters for example
on their cell membranes.
  However some sugar alcohols like erythritol readily penetrate human
tissue, are completely non-toxic (not metabolized), and offer the
potential for good freeze-dry preservation of tissue, albet at storage
temperatures somewhat below ambient.

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