How does antifreeze protein stop ice nucleation?

Abstract

The antifreeze effect of Antifreeze Proteins (AFPs) on ice nucleation, which was neglected in most studies, was examined based on a a??micro-sized ice nucleationa?? technique in this study. It follows from our experiments antifreeze proteins can inhibit the ice nucleation process by adsorbing onto both the surface of ice nuclei and dust particles, which leads to an increase of the ice nucleation barrier and the desolvation kink kinetics barrier, respectively. It was found that the antifreeze activity of AFPs can be enhanced either by their aggregation at higher concentration or by adding electrolyte into AFP solutions. This promotion in antifreeze activity is attributed to optimal packing of AFP III molecules on the surface of the ice nuclei at or above the Critical Aggregation Concentration (CAC), and the screening effect of electrolyte to the surface charge of AFP molecules, respectively. This study enables us to obtain a comprehensive understanding on the antifreeze mechanism of AFPs for the first time.