Chakrabartty A, Hew C L
Research Institute, Hospital for Sick Children, Toronto, Canada.
Eur J Biochem. 1991 Dec 18;202(3):1057-63. doi: 10.1111/j.1432-1033.1991.tb16470.x.
The antifreeze polypeptide (AFP) from the winter flounder displays partial alpha-helix formation at lower temperatures. To investigate the relationship between antifreeze activity and alpha-helical structure, we designed and then chemically synthesized an AFP analog with enhanced alpha-helicity, and compared its conformation and antifreeze properties with those of the native AFP. The synthetic analog was more helical than the native AFP; however, the antifreeze activity of both peptides were identical. The antifreeze activity of the peptides displayed a strong pH dependence, which paralleled pH-induced changes in helix content. At pH 8.5, the antifreeze activity of both peptides displayed identical concentration dependences. In addition to antifreeze activity measurements, the effects of the peptides on the rate of ice crystal growth were also measured. While both peptides affected the a- and c-axis growth rates of ice crystals, the highly helical analog was able to exert its effect on ice crystal growth rates at 7-8-fold lower concentrations than the native AFP. These data indicate that there is a direct but complex relationship between alpha-helicity and antifreeze activity.
来自美洲拟鲽的抗冻多肽（AFP）在较低温度下会形成部分α-螺旋结构。为了研究抗冻活性与α-螺旋结构之间的关系，我们设计并化学合成了一种具有增强α-螺旋性的AFP类似物，并将其构象和抗冻特性与天然AFP进行了比较。合成类似物比天然AFP具有更多的螺旋结构；然而，两种肽的抗冻活性是相同的。肽的抗冻活性表现出强烈的pH依赖性，这与pH诱导的螺旋含量变化平行。在pH 8.5时，两种肽的抗冻活性表现出相同的浓度依赖性。除了测量抗冻活性外，还测量了肽对冰晶生长速率的影响。虽然两种肽都影响冰晶的a轴和c轴生长速率，但高度螺旋的类似物能够在比天然AFP低7至8倍的浓度下对冰晶生长速率产生影响。这些数据表明α-螺旋性与抗冻活性之间存在直接但复杂的关系。
