Wöhrmann A
Institut für Polarökologie, Universität Kiel.
Tierarztl Prax. 1996 Feb;24(1):1-9.
Two types of antifreezes have been isolated from polar and northern temperate fishes so far. They are either glycopeptides or peptides. Whereas these proteins have only a very small effect on the melting temperature of ice, the temperature of these fish can fall to nearly 1 degree below the melting point before ice crystals grow. This phenomenon is called thermal hysteresis, in contrast to the normal colligative effect of solutes. All Antarctic notothenioids (perches) investigated so far have the typical antifreeze glycoproteins (AFGP) with the tripeptide Ala-Ala-Thr and the disaccharide Gal-GalNAc. In the Antarctic silverfish Pleuragramma antarcticum there could be found a novel GlcNAc containing antifreeze glycoprotein, the PAGP. The antifreezes not only lower the freezing temperature, but they also retard recrystallization on frozen storage. Antifreeze proteins thus could be useful for biotechnology and cryomedicine in the future. Since some are now synthesized chemically or by genetic engineering, they no longer have to be isolated from fish blood.
迄今为止，已从极地和北温带鱼类中分离出两种类型的抗冻剂。它们要么是糖肽，要么是肽。尽管这些蛋白质对冰的熔点影响非常小，但这些鱼的体温可以降至比熔点低近1度，然后冰晶才开始生长。与溶质的正常依数性效应相反，这种现象称为热滞。到目前为止，所有已研究的南极南极鱼亚目鱼类（鲈形目）都具有典型的抗冻糖蛋白（AFGP），其含有三肽丙氨酸-丙氨酸-苏氨酸和二糖半乳糖-N-乙酰半乳糖胺。在南极银鱼南极冰鱼中，可以发现一种新型的含N-乙酰葡糖胺的抗冻糖蛋白，即PAGP。抗冻剂不仅降低了冰点，而且还能延缓冷冻储存时的重结晶。因此，抗冻蛋白未来可能对生物技术和低温医学有用。由于现在有些抗冻蛋白是通过化学合成或基因工程生产的，所以不再需要从鱼血中分离。
