Ice Growth Acceleration by Antifreeze Proteins Leads to Higher Thermal Hysteresis Activity

<p>Since some antifreeze proteins and glycoproteins (AF(G)Ps) cannot directly bind to all crystal planes, they change ice crystal morphology by minimizing the area of the crystal planes to which they cannot bind until crystal growth is halted. Previous studies found that growth along the <i>c</i>-axis (perpendicular to the basal plane, the crystal plane to which these AF(G)Ps cannot bind) is accelerated by some AF(G)Ps, while growth of other planes is inhibited. The effects of this growth acceleration on crystal morphology and on the thermal hysteresis activity are unknown to date. Understanding these effects will elucidate the mechanism of ice growth inhibition by AF(G)Ps. Using cold stages and an Infrared laser, ice growth velocities and crystal morphologies in AF(G)P solutions were measured. Three types of effects on growth velocity were found: concentration-dependent acceleration, concentration-independent acceleration, and concentration-dependent deceleration. Quantitative crystal morphology measurements in AF(G)P solutions demonstrated that adsorption rate of the proteins to ice plays a major role in determining the morphology of the bipyramidal crystal. These results demonstrate that faster adsorption rates generate bipyramidal crystals with diminished basal surfaces at higher temperatures compared to slower adsorption rates. The acceleration of growth along the <i>c</i>-axis generates crystals with smaller basal surfaces at higher temperatures leading to increased growth inhibition of the entire crystal.<a></a></p>

Ice Growth Acceleration by Antifreeze Proteins Leads to Higher Thermal Hysteresis Activity

<p>Since some antifreeze proteins and glycoproteins (AF(G)Ps) cannot directly bind to all crystal planes, they change ice crystal morphology by minimizing the area of the crystal planes to which they cannot bind until crystal growth is halted. Previous studies found that growth along the <i>c</i>-axis (perpendicular to the basal plane, the crystal plane to which these AF(G)Ps cannot bind) is accelerated by some AF(G)Ps, while growth of other planes is inhibited. The effects of this growth acceleration on crystal morphology and on the thermal hysteresis activity are unknown to date. Understanding these effects will elucidate the mechanism of ice growth inhibition by AF(G)Ps. Using cold stages and an Infrared laser, ice growth velocities and crystal morphologies in AF(G)P solutions were measured. Three types of effects on growth velocity were found: concentration-dependent acceleration, concentration-independent acceleration, and concentration-dependent deceleration. Quantitative crystal morphology measurements in AF(G)P solutions demonstrated that adsorption rate of the proteins to ice plays a major role in determining the morphology of the bipyramidal crystal. These results demonstrate that faster adsorption rates generate bipyramidal crystals with diminished basal surfaces at higher temperatures compared to slower adsorption rates. The acceleration of growth along the <i>c</i>-axis generates crystals with smaller basal surfaces at higher temperatures leading to increased growth inhibition of the entire crystal.<a></a></p>

Experimental correlation between thermal hysteresis activity and the distance between antifreeze proteins on an ice surface

Temperature-controlled microfluidic devices and fluorescence microscopy illustrate the correlation between freezing-point depression and the distance between antifreeze proteins on an ice surface.

The Thermal Hysteresis of the Type I Antifreeze Protein ‘HPLC-6’: The Effect of Small System

According to Hill’s thermodynamics theory for small system, the effect of small system on the thermal hysteresis activity of type I antifreeze protein ‘HPLC-6’ is discussed in this article. We conclude that when the solution is very dilute, the effect is not visible, and as the concentration increases, the effect becomes more visible than before, and the result also shows that the thermal hysteresis temperature becomes larger when the effect of small system is considered.