[This is a slightly more considered summary of recent work on
cryoprotectants, which appears as my Crucible column in the May
issue of Chemistry World. The links to the papers discussed can
be found in the previous blog entry below.] When the going gets
tough, the tough get sweet. There are many physiological
responses to cold conditions, from goose pimples (useless for
humans, handier for hairier beasts) to the famous antifreeze
proteins of fish. But one of the common strategies for insects
is to fill their cells with sugar. It’s still something of a
mystery why this helps. Cold poses diverse threats to life. Ice
crystals in the body can simply rupture cell walls, which is why
frozen strawberries thaw to a mush. And below about –20 degC
protein molecules themselves start to unravel, a process called
cold denaturation. That’s not well understood yet either,
although a recent paper suggests it involves weakening of the
force between hydrophobic (water-repelling) parts of proteins
that normally binds the folded