The objective of this proposal is to facilitate a detailed understanding of how antifreeze glycoproteins (AFGPs) inhibit ice crystal growth. Towards this end, our laboratory has synthesized a series of first generation AFGP analogues and assessed their ability to inhibit ice crystal growth. Our approach centers on the preparation of glycosylated tripeptide building blocks that possess carbon-carbon linkages instead of carbon-oxygen linkages at the anomeric center. These building blocks (referred to as monomers) have been assembled into structural AFGP analogues using conventional solid phase synthesis (SPS). Preliminary data has shown that two of our C-linked AFGP analogues have antifreeze activity. This application describes studies designed to address what forces (hydrophilic or hydrophobic interactions etc.) are involved in AFGP function, and also, what structural features are necessary for antifreeze activity. The fact that the structures of these mimics are dramatically different than native AFGP suggests that the rational design of low molecular weight synthetic antifreezes is possible. Such compounds have tremendous potential as cryoprotective agents to protect cells from freeze-thaw damage and thus, have applications in cryomedicine where alternatives for the long-term storage of tissues and organs are urgently required. In addition, the concept of preventing or modifying ice crystal growth is a fundamental one that is closely related to biomineralization processes since; many biological molecules absorb onto crystalline surfaces and subsequently alter crystal growth. Examples of such processes include the deposition of cholesterol, the formation of gal bladder and kidney stones as well as consolidated biominerals such as bone and enamel. As a result, a detailed mechanistic understanding of how biological antifreezes function may have direct applications in many biomolecular processes of current medical interest.
