フッ素化学を足がかりとする不凍作用物質の設計と合成

抄録

The antifreeze glycoproteins [AFGPs] are large molecules with molecule weights of 2.6-33 kDa, which exhibit prominent antifreeze property and enable their organisms to survive in below the melting point of water. While AFGPs have gained much attention in recent years, their availability is highly limited to the isolation from natural resources. Although the total syntheses of AFGPs have been reported, the synthetic methods have been limited due to their inherent gigantic molecular structures. Thus the development of efficient synthetic alternatives of AFGPs with middle molecules is highly desirable. We herein design the novel candidates of antifreeze molecules consisting of galactose-conjugated fluorinated and non-fluorinated proline oligomers. They were designed based on the PP II helix with hydrophilic and lipophilic parts, which could induce the potential antifreeze property. The target galactose-proline oligomers were synthesized, and their physical properties were evaluated. Despite our expectation, the non-fluorinated galactose-proline oligomers showed weak antifreeze activity in contrast to the fluorinated analogues. The difference in antifreeze activity would be attributed to the fluorine gauche effect, which induces a different conformation in fluorinated prolines from that of natural proline. These results suggest that the 3D structures of the galactose-conjugated fluorinated and non-fluorinated proline oligomers are critical for their antifreeze properties.