We study the properties of water at the surface of an antifreeze protein with femtosecond surface sum frequency generation spectroscopy. We find clear evidence for the presence of ice-like water layers at the ice-binding site of the protein in aqueous solution at temperatures above the freezing point. Decreasing the temperature to the biological working temperature of the protein (0°C to -2°C) increases the amount of ice-like water, while a single point mutation in the ice-binding site is observed to completely disrupt the ice-like character and to eliminate antifreeze activity. Our observations indicate that not the protein itself but ordered ice-like water layers are responsible for the recognition and binding to ice.
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America (PNAS)|
|Publication status||Published - 16 Dec 2014|
- Antifreeze proteins
- Protein hydration
- Sum frequency generation