Structural Characteristics of the Antifreeze Proteins

Structural Characteristics of the Antifreeze Proteins (AFP)
and Glycoproteins (AFGP)

CharacteristicAFGPAFP Type IAFP Type IIAFP Type IIIAFP Type IV
Molecular Mass(Daltons)2,600 - 33,0003,300 - 4,50011,000 - 24,0006,50012,229
Primary Structure(alanine-alanine- threonine)n disaccharidealanine-rich multiple of eleven aa repeatscystine-rich, disulphide linkedgeneral17% glutamine,no
disulphide bridges,
Carbohydrateyesnono (exception: smelt has <3% carbohydrate)nono
Secondary Structureexpanded alpha helical amphiphilicbeta sheetbeta sandwichamphipathic alpha helical
Tertiary Structurenot determined100% helixnot determinednot determinedfour-helix
antiparallel bundle
Biosynthesismultiproteinprepro AFPprepro AFP (?)pro AFPno post-translational
Protein Components872-6121
Gene Copiesnot determined80 - 1001530 -150not determined
Natural Source Antarctic notothenioids;

Northern cods (Atlantic cod, Greenland cod)

right-eyed flounders (winter flounder);

sculpins (shorthorn)

sea raven;



ocean pout;


Longhorn sculpin

References on Antifreeze Proteins