Antifreeze Protein Binds Irreversibly to Ice

BRASLAVSKY I.; PERTAYA N.; DI PRINZIO, CARLOS LEONARDO

Baltimore, MD- USA

Congreso; MAR06 Meeting of The American Physical Society; 2006

The American Physical Society

Many organisms are protected from freezing by antifreezeproteins (AFPs), which bind to ice and prevent its growth by a mecha-nism not completely understood. Although it has been postulated thatAFPs would have to bind irreversibly to arrest the growth of an ice crys-tal bathed in excess liquid water, the binding forces seem insu±cient tosupport such a tight interaction. By putting a °uorescent tag on a ¯shAFP, we were able to visualize AFP binding to ice and demonstrate, bylack of recovery after photo-bleaching, that it is indeed irreversible. Be-cause even the most avid protein/ligand interactions exhibit reversibil-ity, this ¯nding is key to understanding the mechanism of antifreezeproteins, which are becoming increasingly valuable in cryopreservationand improving the frost tolerance of crops.