Although dehydrins show cryoprotective activities for freeze-sensitive enzymes, the underlying mechanism is still under investigation. Here, we report that F-segments conserved in some dehydrins cryoprotected lactate dehydrogenase (LDH) as well as K-segments, which were previously identified as cryoprotective segments of dehydrins. The cryoprotective activity levels of four F-segments of Arabidopsis dehydrins were similar to that of a typical K-segment. Amino acid substitution experiments indicated that the activity of the F-segment of Arabidopsis COR47 (designated as Fseg) depended on the hydrophobic residues (L, F, and V). Intriguingly, when all the amino acids other than the hydrophobic residues were changed to glycine, the cryoprotective activity did not change, suggesting that the hydrophobic amino acids were sufficient for Fseg activity. Circular dichroism analysis indicated that Fseg was mainly disordered in aqueous solution as well as Fseg_Φ/T, in which the hydrophobic residues of Fseg were changed to T. This suggested that the hydrophobic interaction might be related to the cryoprotective activities of Fseg.

中文翻译：

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拟南芥脱水蛋白的 F 片段显示出乳酸脱氢酶的冷冻保护活性，具体取决于疏水残基

尽管脱水素对冷冻敏感酶具有冷冻保护活性，但其潜在机制仍在研究中。在这里，我们报告了在一些脱水素冷冻保护乳酸脱氢酶 (LDH) 以及 K 段中保守的 F 片段，这些片段以前被确定为脱水素的冷冻保护片段。拟南芥脱水蛋白的四个 F 节段的冷冻保护活性水平与典型的 K 节段相似。氨基酸取代实验表明拟南芥COR47的F段（命名为Fseg）的活性取决于疏水残基（L、F和V）。有趣的是，当除疏水残基以外的所有氨基酸都变成甘氨酸时，冷冻保护活性没有改变，这表明疏水氨基酸足以实现 Fseg 活性。