Interactions of β-helical antifreeze protein mutants with ice
Interactions of β-helical antifreeze protein mutants with ice
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DOI：
10.1021/cg800066g
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发表时间：
2008-08-01
影响因子：
3.8
通讯作者：
Braslavsky, Ido
中科院分区：
文献类型：
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作者：
Bar, Maya;Celik, Yeliz;Braslavsky, Ido
来自黄粉虫的β-螺旋抗冻蛋白(TmAFP)的折叠被证明对多种氨基酸替换具有令人惊讶的耐受性，从而能够构建一组突变体，显示单一氨基酸类型的网格，而不是冰结面上的苏氨酸。这些突变体保持了野生型蛋白质中氨基酸间距的规律性，但表面具有不同的官能团，通过测量热滞和观察它们存在下生长的冰来测试抗冻活性。我们发现，没有一个突变体表现出这种高度活跃的抗冻蛋白野生型版本的戏剧性活性。然而，含有4个缬氨酸或酪氨酸的突变体取代了TmAFP冰结面中心的苏氨酸，表现出残余的热滞活性，并对冰晶形态产生了显著影响。在冰面结合抗冻蛋白吸收-抑制机制的两阶段模型的背景下对结果进行了讨论。
The fold of the beta-helical antifreeze protein from Tenebrio molitor (TmAFP) proved to be surprisingly tolerant of multiple amino acid substitutions, enabling the construction of a panel of mutants displaying grids of single amino acid types in place of the threonines on the ice-binding face. These mutants, maintaining the regularity of amino acid spacing found in the wildtype protein but with different functional groups on the surface, were tested for antifreeze activity by measuring thermal hysteresis and observing ice grown in their presence. We found that no mutant exhibited the dramatic activity of the wild-type version of this hyperactive antifreeze protein. However, mutants containing four valines or tyrosines in place of the threonines in the center of the TmAFP ice-binding face showed residual thermal hysteresis activity and had marked effects on ice crystal morphology. The results are discussed in the context of a two-stage model for the absorption-inhibition mechanism of antifreeze protein binding to ice surfaces.