Melnik B S, Finkelstein A V
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow oblast, 142290 Russia.
Biology Department, Moscow State University, Moscow, 119192 Russia.
Mol Biol (Mosk). 2022 Mar-Apr;56(2):343-352. doi: 10.31857/S0026898422020112.
Antifreeze proteins, expressed in cold-blooded organisms, prevent ice formation in their bodies, and thus help them to survive in extremely cold winter temperatures. However, the mechanism of action of these proteins is still not clear. In any case, it is not simply a decrease in the temperature of normal ice formation. In this work, investigating the ice-binding protein (a mutant form of the antifreeze protein cfAFP from the spruce budworm Choristoneura fumiferana, which overwinters in needles), we showed that this antifreeze protein does not at all lower the freezing point of water and, paradoxically, increases the melting point of ice. On the other hand, calculations based on the theory of crystallization show that at temperatures of 0° to -30°C ice can only appear on surfaces that contact water, but not in the body of water. These facts suggest a new perspective on the role of antifreeze proteins: their task is not (as it is commonly believed) to bind with nascent ice crystals already formed in the organism and stop their growth, but to bind to those surfaces, on which ice nuclei can appear, and thus completely inhibit the ice formation in supercooled water or biological fluid.
抗冻蛋白在冷血生物中表达，可防止其体内形成冰，从而帮助它们在极其寒冷的冬季温度下生存。然而，这些蛋白质的作用机制仍不清楚。无论如何，这不仅仅是正常结冰温度的降低。在这项研究中，我们研究了冰结合蛋白（一种来自云杉芽卷叶蛾的抗冻蛋白cfAFP的突变形式，该蛾在针叶中越冬），结果表明这种抗冻蛋白根本不会降低水的冰点，而且自相矛盾的是，它会提高冰的熔点。另一方面，基于结晶理论的计算表明，在0°至-30°C的温度下，冰只能出现在与水接触的表面上，而不会出现在水体中。这些事实为抗冻蛋白的作用提供了一个新的视角：它们的任务不是（如人们普遍认为的那样）与生物体中已经形成的新生冰晶结合并阻止其生长，而是与那些可能出现冰核的表面结合，从而完全抑制过冷水或生物流体中的冰形成。
