Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India.
Hindustan Unilever R&D, 64 Whitefield Main Road, Bengaluru 560066, India.
Langmuir. 2020 Mar 10;36(9):2439-2448. doi: 10.1021/acs.langmuir.0c00065. Epub 2020 Feb 26.
The antifreeze activity of a type-III antifreeze protein (AFP) expressed in ocean pout (Zoarces americanus) is compared with that of a specific mutant (T18N) using all-atom molecular dynamics simulations. The antifreeze activity of the mutant is only 10% of the wild-type AFP. The results from this simulation study revealed the following insights into the mechanism of antifreeze action by type-III AFPs. The AFP gets adsorbed to the advancing ice front due to its hydrophobic nature. A part of the hydrophobicity is caused by the presence of clathrate structure of water molecules near the ice-binding surface (IBS). The mutation in the AFP disrupts this structure and thereby reduces the ability of the mutant to adsorb to the ice-water interface leading to the loss of antifreeze activity. The mutation, however, has no effect on the ability of the adsorbed protein to bind to the growing ice phase. Simulations also revealed that all surfaces of the protein can bind to the ice phase, although the IBS is the preferred surface.
使用全原子分子动力学模拟，比较了在美洲拟庸鲽（Zoarces americanus）中表达的 III 型抗冻蛋白（AFP）与特定突变体（T18N）的抗冻活性。该突变体的抗冻活性仅为野生型 AFP 的 10%。这项模拟研究的结果揭示了 III 型 AFP 抗冻作用机制的以下见解。由于其疏水性，AFP 会因疏水性而被吸附到前进的冰前沿。一部分疏水性是由于在冰结合表面（IBS）附近存在水分子的笼形结构引起的。AFP 中的突变破坏了这种结构，从而降低了突变体吸附到冰-水界面的能力，导致抗冻活性丧失。然而，该突变对吸附蛋白与生长冰相结合的能力没有影响。模拟还表明，尽管 IBS 是首选表面，但蛋白质的所有表面都可以与冰相结合。
