Polar fish provide biological antifreeze molecules

Teleost fish that inhabit the freezing waters of the Arctic and Antarctic produce antifreeze glycoproteins (AFGPs) that protect their tissues from damage by ice crystal formation. In August 16 Bioconjugate Chemistry, Robert Ben and colleagues from the Department of Chemistry, State University of New York at Binghamton, describe a process for manufacturing and modifying these molecules so that they can be used in biological and medical applications.

There are 8 classes of AFGP, which differ in molecular weight — class 1–4 are 20–33 kDa and class 5–8 are 19–2.2 kDa — but which share the same L-threonyl-L-alanyl-L-alanyl tripeptide backbone. They act by adsorption-inhibition in which the AFGP binds to the surface of a growing ice crystal. The ice continues to grow within this framework, eventually reaching a point at which it becomes energetically unfavourable to add further molecules to the ice lattice. A localised freezing point depression occurs (the Kelvin ...