AFP binds to the surface of ice at temperatures slightly below 0˚C. AFP can strongly inhibit the growth and assembly of many small ice crystals that occur at the moment when water freezes. It has not been understood the reason why AFP can instantly bind to ice and what AFP structure makes it possible, so that it was strongly expected to clarify the manner of hydration and its relationship to ice-binding function of AFPs whose ice-binding strength are different.

In collaboration with the National Institutes for Quantum and Radiological Science and Technology, the researchers discovered that a network of water molecules was organized into ice-like geometry on the surface of AFP, which can easily merge with, and freeze to the embryo ice crystals to inhibit their further growth. The power to bind to ice is strengthened when AFP’s water network contains a cluster with a perfect tetrahedral structure.

This new discovery explained for the first time why AFP can instantly bind to ice and inhibit ice growth. In the future, if it becomes possible to artificially produce a substance that accompanies the surface-bound-waters in ice-like arrangement, it will be utilized to develop a new energy-saving technology that can cryopreserve cells and tissues at temperatures slightly below 0˚C.