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不凍タンパク質の構造と機能
津田, 栄;新井, 達也
Permalink : http://hdl.handle.net/2115/89118
JaLCDOI : 10.14943/lowtemsci.81.51
KEYWORDS : 不凍タンパク質;単結晶氷;多結晶氷;熱ヒステリシス;凍結濃縮;Antifreeze protein;single ice crystal;thermal hysteresis;freeze-induced concentration;ice-like waters
Abstract
我々が普段目にする氷は無数の単結晶氷の融合物，即ち多結晶氷である．単結晶氷は規則的に配列した水分子でできているが，これと同じ規則性をもつ水分子が不凍タンパク質（Antifreeze Protein，AFP）の分子表面にも存在することが最近の研究から分かって来た．即ち，AFPは小さな氷結晶を表面にまとったタンパク質と言うことができる．この様な物質が水中に存在するとき，その水を0℃以下に冷やすとどのようなことが起こるのだろうか？AFPは生物にどのような能力を付与しているのだろうか？本稿では，特に魚類由来AFPの構造と機能に関する著者らの研究を紹介する．
A general block of ice is composed of an infinite number of single ice crystals, which is called ice polycrystalline state. Antifreeze protein (AFP) is a macromolecule that locates regularly organized hydration waters on its surface, whose arrangement is also adopted in a single ice crystal. As the consequence, AFP can specifically bind to single ice crystals, which prevents the ice polycrystalline state formation. We have been performed exploration of AFP against various cold-adapted organisms since the late 1990s, and found that many edible fishes available in the general Japanese food markets contain AFP in their body fluid. This finding enabled us to develop a mass-preparation technique of fish-derived AFPs, for which we have been performed structural and functional analyses and technological applications for many years. The advanced knowledge obtained from our results may ultimately realize a new AFP-technology that may prevent water freezing though the binding to single ice crystals, which may keep alive cells, tissues, and animals in the supercooled environment. The present review describes the overview of the waterfreezing mechanism and our research findings on the fish AFPs including their structure, function, and applicability for both industry and medical fields.
A general block of ice is composed of an infinite number of single ice crystals, which is called ice polycrystalline state. Antifreeze protein (AFP) is a macromolecule that locates regularly organized hydration waters on its surface, whose arrangement is also adopted in a single ice crystal. As the consequence, AFP can specifically bind to single ice crystals, which prevents the ice polycrystalline state formation. We have been performed exploration of AFP against various cold-adapted organisms since the late 1990s, and found that many edible fishes available in the general Japanese food markets contain AFP in their body fluid. This finding enabled us to develop a mass-preparation technique of fish-derived AFPs, for which we have been performed structural and functional analyses and technological applications for many years. The advanced knowledge obtained from our results may ultimately realize a new AFP-technology that may prevent water freezing though the binding to single ice crystals, which may keep alive cells, tissues, and animals in the supercooled environment. The present review describes the overview of the waterfreezing mechanism and our research findings on the fish AFPs including their structure, function, and applicability for both industry and medical fields.
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