Antifreeze Glycoprotein Activity Correlates with Long-Range Protein-Water Dynamics

ArticleinJournal of the American Chemical Society 132(35):12210-1 · September 2010with21 Reads
Impact Factor: 12.11 · DOI: 10.1021/ja1051632 · Source: PubMed

    Abstract

    Antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs) enable the survival of organisms living in subfreezing habitats and serve as preservatives. Although their function is known, the underlying molecular mechanism was not understood. Mutagenesis experiments questioned the previous assumption of hydrogen bonding as the dominant mechanism. We use terahertz spectroscopy to show that antifreeze activity is directly correlated with long-range collective hydration dynamics. Our results provide evidence for a new model of how AFGPs prevent water from freezing. We suggest that antifreeze activity may be induced because the AFGP perturbs the aqueous solvent over long distances. Retarded water dynamics in the large hydration shell does not favor freezing. The complexation of the carbohydrate cis-hydroxyl groups by borate suppresses the long-range hydration shell detected by terahertz absorption. The hydration dynamics shift toward bulk water behavior strongly reduces the AFGP antifreeze activity, further supporting our model.