Boreal pollen contain ice-nucleating as well as ice-binding 'antifreeze' polysaccharides.
Boreal pollen contain ice-nucleating as well as ice-binding 'antifreeze' polysaccharides.
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DOI：
10.1038/srep41890
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发表时间：
2017-02-03
影响因子：
4.6
通讯作者：
Koop T
中科院分区：
文献类型：
--
作者：
Dreischmeier K;Budke C;Wiehemeier L;Kottke T;Koop T
冰的成核和生长是一个重要而广泛的环境过程。因此，自然界已经开发出促进或抑制冰晶形成的方法，例如细菌中的冰成核蛋白或极地鱼类中的冰结合抗冻蛋白。最近，人们发现桦树花粉悬浮在水中时会释放出冰核大分子。在这里，我们表明，桦树花粉洗涤水也表现出冰结合性能，如冰成型和冰重结晶抑制，类似于抗冻蛋白。我们目前的光谱证据表明，无论是冰成核以及冰结合分子的多糖轴承羧酸基团。光谱表明，这两种多糖组成的非常相似的化学部分，但离心过滤表明分子大小的差异：冰成核只发生在100 kDa的过滤器的上清液，而冰成形强烈增强的滤液。这一发现可能表明，较大的冰成核多糖由较小的冰结合多糖簇组成，或者后者是冰成核多糖的片段。最后，类似的多糖松和桤木花粉释放也显示出冰成核以及冰结合能力，这表明一个共同的机制与冰之间的相互作用的几个北方花粉与大气过程和防冻保护的影响。
Ice nucleation and growth is an important and widespread environmental process. Accordingly, nature has developed means to either promote or inhibit ice crystal formation, for example ice-nucleating proteins in bacteria or ice-binding antifreeze proteins in polar fish. Recently, it was found that birch pollen release ice-nucleating macromolecules when suspended in water. Here we show that birch pollen washing water exhibits also ice-binding properties such as ice shaping and ice recrystallization inhibition, similar to antifreeze proteins. We present spectroscopic evidence that both the ice-nucleating as well as the ice-binding molecules are polysaccharides bearing carboxylate groups. The spectra suggest that both polysaccharides consist of very similar chemical moieties, but centrifugal filtration indicates differences in molecular size: ice nucleation occurs only in the supernatant of a 100 kDa filter, while ice shaping is strongly enhanced in the filtrate. This finding may suggest that the larger ice-nucleating polysaccharides consist of clusters of the smaller ice-binding polysaccharides, or that the latter are fragments of the ice-nucleating polysaccharides. Finally, similar polysaccharides released from pine and alder pollen also display both ice-nucleating as well as ice-binding ability, suggesting a common mechanism of interaction with ice among several boreal pollen with implications for atmospheric processes and antifreeze protection.