A diminished role for hydrogen bonds in antifreeze protein binding to ice
A diminished role for hydrogen bonds in antifreeze protein binding to ice
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DOI：
10.1021/bi970817d
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发表时间：
1997-12-02
期刊：
影响因子：
2.9
通讯作者：
Sonnichsen, FD
中科院分区：
文献类型：
--
作者：
Chao, HM;Houston, ME;Sonnichsen, FD
比目鱼中最丰富的I型抗冻蛋白（AFP（I））的同种型（HPLC-6）是一个37个氨基酸长、富含丙氨酸的α-螺旋肽，含有4个间隔11个氨基酸的Thr。通常认为HPLC-6通过Thr和相邻Asx残基与冰晶格{2021}平面上的氧原子之间的氢键匹配来结合冰。结果是非平衡凝固点降低到熔点以下（热滞后）。合成了HPLC-6和其中中心两个Thr被Ser或瓦尔替换的两种变体。Ser变体实际上是无活性的，而在瓦尔变体中仅观察到轻微的活性损失。CD、超离心和NMR研究表明，与HPLC-6相比，变体没有显著的结构变化或聚集。这些结果提出了问题的氢键的作用，并建议一个更重要的作用熵效应和货车范德华相互作用结合AFP冰。
The most abundant isoform (HPLC-6) of type I antifreeze protein (AFP(I)) in winter flounder is a 37-amino-acid-long, alanine-rich, alpha-helical peptide, containing four Thr spaced 11 amino acids apart. It is generally assumed that HPLC-6 binds ice through a hydrogen-bonding match between the Thr and neighboring Asx residues to oxygens atoms on the {2021} plane of the ice lattice. The result is a lowering of the nonequilibrium freezing point below the melting point (thermal hysteresis). HPLC-6, and two variants in which the central two Thr were replaced with either Ser or Val, were synthesized, The Ser variant was virtually inactive, while only a minor loss of activity was observed in the Val variant, CD, ultracentrifugation, and NMR studies indicated no significant structural changes or aggregation of the variants compared to HPLC-6. These results call into question the role of hydrogen bonds and suggest a much more significant role for entropic effects and van der Waals interactions in binding AFP to ice.