不凍糖タンパク質が氷結晶成長に及ぼす効果の面方位依存性と生体の凍結抑制

抄録

  The growth of inorganic crystals under the effect of biological macromolecules added as an impurity is of special importance in relation to the biocrystallization. We present the results of the free growth experiments of ice in supercooled water containing an impurity of glycoprotein, which is a bio-macromolecule that functions as ‘antifreeze’ in living organisms in a subzero environment. The interface direction dependence for the effects of antifreeze protein among the basal, prismatic and pyramidal faces were clearly shown on the basis of growth experiments carried out in both the laboratory and the International Space Station. The growth rates for prismatic and pyramidal faces were suppressed by the impurity effect of antifreeze glycoprotein, in contrast acceleration and oscillation of the normal growth rates were newly discovered as an antifreeze protein effect for the basal face. This interface direction dependence for the effect of antifreeze glycoprotein leads to a better understanding of the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing.