Antifreeze protein hydration waters: Unstructured unless bound to ice
Antifreeze protein hydration waters: Unstructured unless bound to ice
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DOI：
10.1073/pnas.1810812115
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
Sean M. Marks;Amish J. Patel
中科院分区：
文献类型：
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作者：
Sean M. Marks;Amish J. Patel
鱼类、昆虫和其他生物如何在寒冷的极地环境中生存？他们这样做的帮助下显着的分子称为抗冻蛋白（AFP），抑制冻结和相关的细胞死亡，尽管存在的浓度低于1重量%（1）。相比之下，汽车防冻剂需要大约20至50重量%的添加剂才能发挥作用（2）。AFP能够在如此低的浓度下抑制冻结，因为与防冻剂不同，它们不依赖于改变水的固有结构;相反，它们与新生的冰核结合并阻止它们生长。因此，能够识别并优先结合大量过量水中的冰是AFP功能的关键（1）。然而，在水和冰之间没有任何化学差异的情况下，AFP如何区分它们？此外，水和冰都是由氢键组成的四面体网络，因此它们之间的结构差异也很微妙。事实上，AFP如何能够执行被吹捧为所有生物学中最具挑战性的分子识别任务之一，长期以来一直是令人惊讶和好奇的来源（1，4）。在PNAS中，Hudait等人（5）通过使用分子模拟研究Tm AFP（一种过度活跃的昆虫AFP），澄清了冰识别难题的重要方面。使这一难题更加令人着迷的是，从细菌到昆虫和鱼类的各种生物体都独立进化出了AFP，这些AFP在序列、结构和冰结合位点（IBS）方面存在显著差异（6，7）。换句话说，不是一个，而是多种多样的基序可以赋予AFP与冰结合的能力。那么，肠易激综合征的特征是什么？它们是如何使AFP结合冰的？[1][2][3][4][5][6][7][8][9][10][11][12][13][14]电子邮件：amish.patel{at}seas.upenn.edu. [1]：#xref-corresp-1-1
How do fish, insects, and other organisms survive in frigid polar environments? They do so with the help of remarkable molecules known as antifreeze proteins (AFPs), which suppress freezing and associated cell death despite being present at concentrations of less than 1 wt % (1). In contrast, automotive antifreeze needs roughly 20 to 50 wt % of the additive to function (2). AFPs are able to suppress freezing at such low concentrations because, unlike antifreeze, they do not rely on altering the inherent structure of water; instead, they bind to nascent ice nuclei and prevent them from growing (3). Thus, being able to recognize and preferentially bind ice in a vast excess of water is the key to AFP function (1). However, in the absence of any chemical differences between water and ice, how do AFPs discriminate between them? Moreover, both water and ice are composed of a tetrahedral network of hydrogen bonds, so even the structural differences between them are subtle. Indeed, how AFPs are able to perform what has been touted as one of the most challenging molecular-recognition tasks in all of biology has long been a source of amazement and intrigue (1, 4). In PNAS, Hudait et al. (5) clarify important aspects of the ice-recognition puzzle by using molecular simulations to study Tm AFP, a hyperactive insect AFP. What makes this puzzle even more fascinating is that a wide array of organisms, ranging from bacteria to insects and fishes, has independently evolved AFPs that display substantial differences in their sequences, structures, and ice-binding sites (IBS) (6, 7). In other words, there is not one, but a diversity of motifs that can confer AFPs with their ice-binding abilities. What, then, are the characteristic features of IBS, and how do they enable AFPs to bind ice? Early … [↵][1]1To whom correspondence should be addressed. Email: amish.patel{at}seas.upenn.edu. [1]: #xref-corresp-1-1