ARTICLE:

• ON THE MOTION OF ANTIFREEZE PROTEIN, ICE GROWTH AND TEMPERATURE DROP IN AN AQUEOUS SOLUTION OF THE PROTEIN  download article

Y. Morikane
Graduate School, Kyoto Institute of Technology, Japan

Yoshimichi Hagiwara
Department of Mechanical and System Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan

M. Shibata
NGK Insulators, Ltd, Japan

ABSTRACT

We observe the gradual, one-directional freezing procedure of the aqueous solution of HPLC6, which is the major fraction of the antifreeze protein type I, in a narrow space between two cover glasses with a high-resolution microscope. The time change in the temperature of the solution is measured with a micro-thermocouple. The location of the protein is obtained from the fluorescence tagged to the protein. It is observed that the proteins gather on the inclined ice/water interface, and slide on the interface towards the depression parts on the interface. Then, the proteins are associated with each other at the depression parts. The velocity of the associated proteins is lower than that of the interface. Thus the interface becomes curved. The curved interfaces cause the serration of interface. Also, long, narrow liquid regions are formed inside the ice from the depression parts due to the highly associated proteins. The opening angles of the depression parts, the titling angles of the serration, and the pitch of the serration depend on the protein concentration and the ice growth velocity.

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