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.

Additional Metadata
Publisher PNAS
Persistent URL dx.doi.org/10.1073/pnas.1414188111
Journal PNAS
Meister, K, Strazdaite, S, DeVries, A.L, Lotze, S, Olijve, L.L.C, Voets, I.K, & Bakker, H.J. (2014). Observation of ice-like water layers at an aqueous protein surface. PNAS, 111(50), 17732–17736. doi:10.1073/pnas.1414188111