Biogenic antifreeze agent

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A biogenic anti-freeze is an anti-freeze that has been produced by living things .


Biological antifreeze agents include low molecular weight compounds and anti-freeze proteins . They occur in particular in organisms from arctic climates. Glycerol , other polyols , urea and glucose , among others , are used as low molecular weight compounds . These are compounds that will readily form hydrogen bonds with neighboring water molecules. This lowers the freezing point within the cells , which prevents perforation of the cell membrane by ice crystals. In some cases, the concentration of water in the cells is also reduced ( anhydrobiosis ).

Most anti-freeze proteins do not prevent cell plasma from freezing, but they can delay it a little. Their effect is based on the fact that they hinder the growth of the ice crystals and shield already formed ice crystals, which could act as crystallization nuclei . As a result, the resulting crystals remain small, the ice becomes fine-grained and cannot destroy the structure of the cell even if it freezes through. After thawing, the cell resumes its normal functions.


In biochemistry, cells for cryopreservation are usually frozen in a freezing medium from the culture medium with dimethyl sulfoxide , e.g. B. in culture medium with 20% (V / V) FCS and 10% (V / V) DMSO. In some cases, ethylene glycol is also used instead of DMSO . In the case of vitrification , on the other hand, an attempt is made to avoid the formation of ice crystals during cooling entirely B. with concentrated glycerol solutions (17 moles per kilogram).

Individual evidence

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