Mass preparation and technological development of an antifreeze protein

Antif reeze protein (AFP) can inhibit ice-growth by accumulating on the surface of ice nuclei formed in nearfreezing water, and can preserve cell function under hypothermic conditions (-0 °C). The objective of this study was to develop new technologies so these properties of AFP can be applied in industry and medicine. Figure 1 compares the principles of current cryotechnology without AFP and the expected cryotechnology utilizing AFP. Common perception is that water freezes at 0 °C; however, spontaneous freezing at 0 °C hardly occurs when liquid water is placed in cold environment such as in the refrigerator (-18 °C). Unfrozen water below 0 °C is generally called supercooled water . Freezing is triggered by natural formation of numerous ice nuclei in supercooled water (Figure 1A, top). The generated ice nuclei successively undergo crystal growth by adsorption of surrounding water molecules, and finally occupy the whole space (Figure 1A, bottom). Thus, a common block of ice is inevitably polycrystalline and not a single crystal of water molecule.