Molecule of the Month: Antifreeze Proteins
Small antifreeze proteins protect cells from damage by ice
Icy Ice Cream
Many Solutions to the Same Problem
Exploring the Structure
Antifreeze Proteins (PDB entry 2pne)
Antifreeze proteins bind to ice crystals, blocking the surface and preventing growth of the crystal. The structure of snow flea antifreeze protein (2pne ) will give you an idea of what this recognition may be like. In the crystal structure, the ice-binding surface of the protein is covered with strings of water molecules (shown here in red). These water molecules are spaced similarly to the water molecules in ice crystals. So you can imagine this protein binding to the geometric lattice of water molecules in ice in a similar way. Click on the image to view an interactive Jmol version.
Topics for Further Discussion
- Antifreeze proteins are examples of convergent evolution. Can you find other examples in the PDB where two entirely different proteins perform the same function?
- The insect antifreeze proteins are examples of solenoidal folds, where the protein chain loops around like a spring. Compare the way the chain is folded in the beetle and moth proteins with the entirely different type of looping fold in the snow flea protein. Can you find other examples of solenoidal folds in the PDB (hint: look at the SCOP classification of these proteins, available at the bottom of the structure browser page).
Related PDB-101 Resources
- Browse Biotechnology
- Browse Molecular Evolution
- S. Venkatesh and C. Dayananda (2008) Properties, potentials, and prospects of antifreeze proteins. Critical Reviews in Biotechnology 28, 57-82.
- A. Regand and H. D. Goff (2006) Ice recrystallization inhibition in ice cream as affected by ice restructuring proteins from winter wheat grass. Journal of Dairy Science 89, 49-57.
- Z. Jia and P. L. Davies (2002) Antifreeze proteins: an unusual receptor-ligand interaction. Trends in Biochemical Sciences 27, 101-106.
December 2009, David Goodselldoi:10.2210/rcsb_pdb/mom_2009_12