Now researchers at the University of California, Davis, are closing in on just how those proteins work. The research could lead to safer storage for food or blood products. It may also help scientists understand how bones and sea-shells are made and how mineral deposits can cause kidney stones and heart disease.

The antifreeze proteins studied at UC Davis, called antifreeze glycoproteins, are long, floppy and covered in sugar molecules that interact with water. Using nuclear magnetic resonance and infrared spectroscopy, Nelly Tsvetkova and colleagues in the UC Davis Biostabilization Laboratory have found that even in ice as cold as minus 60 degrees Celsius (minus 76 F), the proteins are surrounded with a shell of liquid water and are constantly moving and changing shape.

"Normally at this temperature, proteins are pretty much solid," said Yin Yeh, professor of applied science at UC Davis. The random structure stops ice crystals from growing and preserves liquid water around the protein, said John Crowe, who with Fern Tablin of the UC Davis School of Veterinary Medicine heads the biostabilization group.

The antifreeze proteins also stabilize cell membranes during chilling, Crowe said. As the temperature drops, the fatty molecules that make up the cell membrane change from a semi-fluid to a gel-like state. As this happens, cell contents can leak out. In another recent paper from the UC Davis group, graduate student Melanie Tomczak, now a researcher at Queen's University in Kingston, Ontario, showed that antifreeze proteins bind to specific sugars on the cell membrane and change its structure, preventing leakage.

The antifreeze glycoproteins were discovered by UC Davis biochemist Robert E. Feeney over 30 years ago. Crowe and Tablin
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Contact: Andy Fell
ahfell@ucdavis.edu
530-752-4533
University of California - Davis
15-Mar-2002