In most animals, intra and extracellular freezing causes tissue damage resulting in death. There are some insects such as Dendroides candensis, which are considered as freeze avoidance insects. These insects utilize antifreeze proteins for their survival. Antifreeze proteins (AFPs) are found in organisms such as insects and fish that live in cold climates. AFPs help for the acclimatization of these organisms. These unique proteins can bind to ice crystals to inhibit its further growth. Insect AFPs usually have high antifreeze activity and antifreeze activity of AFPs can be enhanced by certain small molecules such as trehalose, citrate and glycerol. Trehalose, a type of sugar disaccharide, is one cryoprotectant utilized as energy by Dendroides candensis. It has been experimentally observed that a trehalose dihydrate crystal has a more favorable crystal growth rate on the (-110) plane and a least favorable rate on the (0-11) plane. Moreover, experimentally it has been observed that trehalose dihydrate solubility changes drastically in the presence of DAFP-1. It is of great interests to reveal the details of how do AFPs recognize the ligands and control the crystal growth of the substances. In addition, AFP binding conformations may yield a better understanding of the function of these remarkable proteins. The results are essential in many scientific fields including chemistry, materials science, and pharmaceutical development.
We thank National Institutes of Health Grant GM086249 for supporting the study. A.R. thanks MURF Undergraduate Research Fellowships.