Fish, insects, bacteria, and plants that live in sub-zero environments rely on antifreeze proteins (AFPs) to survive. AFPs bind to the surface of ice crystals and prevent them from growing. Industrially, AFPs are used to control ice-crystal growth in the production of ice cream and frozen yogurt.
Peter Davies and co-workers, Queen’s University, Ontario, Canada, have reported a X-ray crystallographic picture of the AFP∶ice interaction. An unobstructed view of the interaction was possible thanks to an exposed ice-binding site in an Antarctic bacterium. This revealed hydrophobic sites that pre-order water near the protein surface into an ice-like cage. Once ordered, the cage can be bound to the surface via the hydrogen bonds of the hydrophilic sites.
In addition to improving the quality of ice cream, this understanding could lead to new AFPs for the preservation of transplant organs and tissues.
- Anchored clathrate waters bind antifreeze proteins to ice
C. P. Garnham, R. L. Campbell, P. L. Davies
Proc. Natl. Acad. Sci. 2011.