Antifreeze polypeptide

Yang DSC, Sax M, Chakrabarty R, Hew CL (1988) Crystal structure of an antifreeze polypeptide and its mechanistic implications. Nature (Lond) 333 232-237... 

Antifreeze polypeptides are found in the blood plasma of bony fishes from the polar and subpolar oceans. The major antifreeze polypeptide (AFP) from winter flounder (37 amino acid residues) is a single alpha-helix [18]. 

Chakrabartty, A., Ananthanarayan, V.S., and Choy, L.H., Structure-function relationships of a winter flounder antifreeze polypeptide. J. Biol. Chem. 264 11307-11312,1989. 

S.M. McDonald, J.W. Brady, and P. Clancy, Molecular dynamics simulations of a winter flounder "antifreeze" polypeptide in aqueous solution, Biopolyniers, 33 (1993) 1481. 

Low, W.-K., Lin, Q., Stathakis, C., Miao, M., Fletcher, G.L., and Hew, C. L. (2001) Isolation and characterization of skin-type, type 1 antifreeze polypeptides from the longhorn sculpin, Myoxocephalus octodecem-spinosus.J. Biol. Chem., 276, 11582-11589. 

Wierzbicki, A., Knight, C.A., Rutland, T.J., Muccio, D.D., Pybus, B.S., and Sikes, C.S. (2000) Structure-function relationship in the antifreeze activity of synthetic alanine-lysine antifreeze polypeptides. Biomacromolecules, 1, 268-274. 

Gong, A., K.V. Ewart, Z. Flu, G.L. Fletcher, and C.L. Flew (1996). Skin antifreeze protein genes of the winter flounder, Pleuronectes americanus, encode distinct and active polypeptides without the secretory signal and prosequences. J. Biol. Chem. 271 4106 1112. 

So far, all AFGP analogs prepared in our laboratory have utilized the L-lysine-glycine-glycine tripeptide unit that is radically different in structure than the core repeating tripeptide unit found in native AFGP. The threonine residue in native AFGP was replaced with lysine for two reasons. Firstly, recent work has demonstrated that an alanine-lysine rich polypeptide possessed weak antifreeze protein-specific activity (26). 

A single attempt to estimate the minimum size of the polypeptide chain needed for antifreeze activity indicated that chains shorter than... 

Fig. 33. Lowering of the freezing temperature by the antifreeze protein of the flounder and a synthetic polypeptide composed of alanine and aspartic acid. The synthetic polypeptide is a random polymer of alanine and threonine in the molar ratio of 2 1. From Ananthanarayanan and Hew (1977b), reproduced with permission.

Ananthanarayanan and Hew (1977b) have recently described the synthesis of a polypeptide with structural similarities to the antifreeze protein from the flounder. The product was a random polymer of... 

Biologically active materials, such as polypeptides and nucleic acids, are composed of many of these polar groups and many apolar residues. Not only are the conformations of the macromolecule influenced by the presence of water as the solvent, but the presence of these macromolecules is able to influence the solvents behaviors. Thus we might look at a system and decide if it could serve as an antifreeze or a good nucleating substrate by first obtaining an understanding of its solution conformations. 

Study of antifreezing properties of different-length segments of the polypeptide chains—determination of the minimum lengths of polymers required. 

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