Section I: Food Process Engineering, KIT (Karlsruhe Institute of Technology), Institute of Process Engineering in Life Sciences, Kaiserstraße 12, Karlsruhe 76131, Germany.
Langmuir. 2021 Oct 12;37(40):11716-11725. doi: 10.1021/acs.langmuir.1c01620. Epub 2021 Sep 29.
Antifreeze proteins (AFPs) are able to influence the ice crystal growth and the recrystallization process due to the Gibbs-Thomson effect. The binding of the AFP leads to the formation of a curved ice surface and it is generally assumed that there is a critical radius between the proteins on the ice surface that determines the maximal thermal hysteresis. Up to now, this critical radius has not yet been proven beyond doubt or only in poor agreement with the Gibbs-Thomson equation. Using molecular dynamics (MD) simulations, the resulting three-dimensional surface structure is analyzed and the location of the critical radius is identified. Our results demonstrate that the correct analysis of the geometry of the ice surface is extremely important and cannot be guessed upfront a simulation. In contrary to earlier expectations from the literature, we could show that the critical radius is not located directly between the adsorbed proteins. In addition, we showed that the minimum temperature at which the system does not freeze is in very good agreement with the value calculated with the Gibbs-Thomson equation at the critical radius, as long as dynamic system conditions are taken into account. This proves on the one hand that the Gibbs-Thomson effect is the basis of thermal hysteresis and that MD simulations are suitable for the prediction of the melting point depression.
抗冻蛋白 (AFPs) 能够通过吉布斯-汤姆逊效应影响冰晶生长和再结晶过程。AFP 的结合导致形成弯曲的冰面，通常假定在冰面上的 AFP 之间存在一个临界半径，该半径决定了最大热滞。到目前为止，这个临界半径还没有得到毫无疑问的证明，或者只是与吉布斯-汤姆逊方程存在较差的一致性。使用分子动力学 (MD) 模拟，分析了所得的三维表面结构，并确定了临界半径的位置。我们的结果表明，对冰面几何形状的正确分析是极其重要的，不能在模拟之前猜测。与文献中的早期预期相反，我们能够表明临界半径并不直接位于吸附的 AFP 之间。此外，我们还表明，只要考虑到动态系统条件，系统不冻结的最低温度与在临界半径处用吉布斯-汤姆逊方程计算的值非常吻合。这一方面证明了吉布斯-汤姆逊效应是热滞的基础，另一方面证明了 MD 模拟适用于预测熔点降低。
